Abstract:
New utility of an existing class of DC galvanically isolated current sourcing circuit topologies for power conversion simultaneously allows improvement in its secondary circuit(s) to power conversion efficiency and reduction in working voltage magnitudes, or simply reduction in working voltage magnitudes, with resulting benefits for reduction in manufacturing cost, reduction in size and weight, and increase in market acceptance, or may simply allow secondary circuit(s) to enable easier provisioning of safety, improvement in reliability, or improvement in efficiency. The magnitude of DC output voltage is optimized at higher value for greater efficiency, while simultaneously optimizing the secondary circuit&#39;s working voltage maximum magnitude at a lower value for greater safety. The method requires full cycle current-compliant input impedance of the secondary power source whereby the secondary of the DC galvanically isolating device behaves in a mode of being a full cycle voltage-compliant current source.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is directed to a method and apparatus for utility to optimize a DC-to-DC power conversion process simultaneously for higher efficiency and for lower limit on the maximum magnitude of working voltages in its secondary circuit(s), or to optimize only for lower limit on the maximum magnitude of working voltages in its secondary circuit(s). 
       BACKGROUND OF THE INVENTION 
       [0002]    All electrical power converters delivering DC power to a load, and deriving this power from an AC source, must process it through at least one stage performing a rectification function. In the case of switch mode (SM) power conversion with DC galvanically isolated secondaries there are typically a minimum of two stages where rectification occurs, the second of such being in the secondary circuit. All DC-to-DC SM power converters with DC galvanically isolated secondaries have at least one stage where rectification occurs, located in the secondary circuit. 
         [0003]    Greater power conversion efficiency results in the secondary circuit from having greater output load voltages, where the increases to the value of output load voltage has the greatest incremental influence on increases to efficiency when the ratio of that load voltage magnitude to the combined voltage magnitudes of forward voltage drops of the secondary rectifier(s) and stray impedance(s) is smallest, this being true due to the same current conducting through the forward voltage drop of the output load also conducting through the power dissipative forward voltage drops of the rectifier(s) and stray impedance(s). 
         [0004]    The terms ‘rectification’, ‘rectifier’, or ‘rectifier(s)’, as used herein shall also be construed to include any means of rectifier optimization such as synchronous rectification which may include but not be limited to diodes, MOSFETs, MOSFETs and diodes, active switching devices, active switching devices and diodes. 
         [0005]    There is increasing market emphasis on producing or procuring solutions for power conversion that are optimized to be efficient, delivering a high percentage of the electrical power they consume from their supplies into electrical power available to their loads. Emphasis on efficiency is due in some applications to market emphasis on optimizing for low total cost of ownership (TCO) of an electrical system, especially where a favorable TCO result is necessary to justify a high initial expenditure for purchase of a system, or in an industry where lowering operating cost is essential to maintaining or improving profitability, cost-competitiveness, or market viability. There is also increasing emphasis on so-called energy efficiency as a national priority in the United States and other countries which are net energy importers. Energy-efficiency encompasses power conversion efficiency, but above all signifies prioritizing efficaciousness of energy utilization. 
         [0006]    An electrical system may comprise power conversion apparatus, cooling apparatus, fixture and housing apparatus, and an output electrical load apparatus. One example of an electrical system where market emphasis is on TCO is that of a luminaire utilizing power LEDs for light generation, where a favorable TCO benefit analysis is often pivotal to a decision by market participants to engage said LED technology through the adoption of system embodiment that successfully preserves at the system level the sought benefit of an efficacious light source that the LEDs embody at their elemental level. The electrical system of the example luminaire should be capable of supporting a favorable TCO analysis by offering low operating costs through having its power conversion efficiency optimized to a suitable level, while limiting the cost of its manufacture through inherently less costly cooling apparatus enabled by higher efficiency, and inherently less costly housing apparatus afforded by a lower maximum secondary working voltage magnitudes. 
         [0007]    For purposes of illustration to demonstrate the effect upon efficiency of the secondary rectifier(s) in an power conversion apparatus, the LED load voltage in a typical luminaire application due to a load comprising a single LED, or several LEDs receiving their power in parallel connection, is assumed to be approximately 3 volts, where an additional forward voltage drop of each current conducting rectifier series electrically connected between transformer output and output load in the secondary circuit may be assumed to be between 0.3 volts and 1.2 volts, and where other additional forward voltage drops due to stray and other impedances also series electrically connected in the secondary circuit between transformer output and output LED load may be assumed to be insignificant by comparison. 
         [0008]    In the case of the example electrical system, an output load may be redesigned so it is optimized to support greater load voltage, either by reconfiguring its LED load to have its several parallel LEDs electrically connected instead in series, or reconfiguring its load comprising only a single LED by replacing it with multiple lower luminosity LEDs electrically connected in series so that they have equivalent total luminosity as the single LED being replaced. It should be assumed for the sake of simplicity with this first illustration that output power remains constant as a function of overall luminosity remaining constant, so LED load current will be decreased as a result of the LED load voltage having been increased for this comparison at constant luminosity between original configuration and reconfigured loads, given that output power is identical for both cases, where power is calculated as the product of load current and load voltage. Higher load voltage will result in higher electrical efficiency than lower load voltage for a constant power load, due to relative reduction in electrical power being dissipated by a decreased load current conducting through the forward drop of the rectifier(s) series electrically connected in the secondary circuit between transformer output and output LED load, compared with the unchanged electrical power continuing to be delivered to the higher voltage of the reconfigured LED output load. 
         [0009]    One may analyze a second case using this example, where the load current remains unchanged and output load voltage as well as output power is increased. For any given load current in this second case, efficiency is increased due to the increased output load voltage magnitude, and its consequence of a now increased proportion of power delivered to the output load, relative to an unchanged amount of power dissipation due to current conducting through the forward drop of the secondary rectifier(s). 
         [0010]    To increase efficiency by increasing output load voltage using a current-compliant voltage source (CCVS) class of topologies would entail a transformer that behaves as a CCVS, which would result in working voltage magnitudes in secondary circuit(s) significantly exceeding the voltage magnitude of the output load, due to the voltage compliant behavior of inductor(s) series electrically connected in secondary circuit(s) conducting current for use by the output load(s), said voltage magnitudes possibly increasing the risk of electric shock to operators who come into physical contact with bare conductors in said secondary circuit(s), or increasing risk of fire or explosion in certain environments. To meet a need for safety in the case of operators coming into physical contact with electrically conductive elements, the power industry has adopted a discipline of redundancy, or equivalent redundancy, regarding electrical insulation systems and maximum permissible working voltage magnitudes; and required that in those situations that safety be maintained despite any single failure occurring. In the case of protecting against fire or explosion in certain high risk environments, criteria are established to maintain working voltage magnitudes below permissible maximum limits despite the simultaneous occurrence of any two failures. It can be anticipated that other cases exist which require criteria be met for an even higher degree of redundancy protection, such as in so-called mission critical applications. 
         [0011]    An operator may be afforded safety protection from electric shock due to physical contact with voltage present on bare conductors of the output load if the secondary circuit ensures that under normal conditions, or due to a single fault, the maximum voltage level considered to be safe shall not be exceeded on the bare conductor of the output load. To address this need a voltage monitor circuit for over-voltage fault detection may be employed which acts to ensure no over-voltage condition exists at the secondary&#39;s output terminals due to any single fault, and in addition the secondary circuit must be constructed to insulate against electric shock by some inherent means such as a grounded or insulated housing protecting the operator from exposure to bare conductors of the secondary circuit exclusive of its output terminals. In the example of a luminaire, where for instance it may be desired to allow an operator to simply screw-in a replacement as for incandescent bulbs by using LED luminaire systems with similar form and function to that of an incandescent bulb, this requirement for a housing of secondary circuits may pose a difficulty assuming no grounding point is available, such as is the case with a traditional incandescent light bulb for instance, and that an appropriate insulating enclosure protecting bare conductors in the secondary circuit from operator contact would be difficult to implement while retaining TCO benefits to luminaire of efficacious LED technology due to reduced housing volume. 
         [0012]    A requirement therefore that is often imposed on any successful solution to an application such as illustrated by the luminaire example is that of electrical safety for the operator. Electrical safety is a function of the human body&#39;s tolerance to applied voltage, reduction to the risk that an operator may come into physical contact with hazardous voltages, and limiting the maximum magnitudes for the two types of voltages to which an operator may come into contact, DC or AC. Safety related to electrical circuits is also a function of addressing circumstances of certain environmental conditions which may allow for increased risk of fire or explosion, and mitigating against these effects by ensuring voltages do not exceed certain thresholds despite the possibility of multiple simultaneous faults occurring. Criteria which address electrical safety provisions for providing protection from electrical shock are found in several industry-accepted electrical standards such as described in the cited reference document: Bob Mammano, Lal Bahra, “Safety Considerations in Power Supply Design”, Texas Instruments. Criteria which address electrical related safety provisions for providing protection from risk of igniting a fire or explosion are found in several industry-accepted electrical standards such as described in the cited reference document: “AN9003-9 A Users Guide To Intrinsic Safety”, October 2006, MTL Instruments, Power Court, Luton, Bedfordshire, England. A circuit may qualify for the classification of ‘Extra Low Voltage’ (ELV) if it protects against the risk or electric shock due to hazardous voltages in the event an operator comes into physical contact with its bare conductors. If protection continues to be effective in the event of any single fault, the circuit may qualify for classification of ‘Safety Extra Low Voltage’ (SELV). If protection continues to be effective, as defined for hazardous environments, in the event of any two simultaneous faults, the circuit may qualify for classification of ‘Intrinsically Safe’ (IS). The subject circuit being considered for its electrical safety or related environmental safety may be an output load, the output terminals of a secondary circuit, or the secondary circuit. Any circuit connected to another may be able to share the same benefit of safety voltage class under usual circumstances. An output load is at a minimum a secondary circuit if it is connected only to the output terminals of a secondary circuit. If said secondary circuit&#39;s output terminals are classified SELV due to limiting its maximum voltage magnitude under both normal or fault conditions, and the output load is incapable of producing higher voltage magnitudes than it is supplied by the secondary circuit, then the output load may also be classified SELV. Output terminals of a secondary circuit may be classified SELV without requiring its secondary circuit be so classified, if no non-SELV bare conductors are external to the secondary circuit enclosure, and if non-SELV bare conductors internal to the secondary circuit are inaccessible to an operator; and if an over-voltage fault detection and fault limit circuit is employed to monitor voltage at said accessible terminals, which acts sufficiently fast in event of a fault to prevent from appearing on said terminals any higher voltage magnitude than intended within the criteria for classification of SELV circuits. In this case it is not necessary for a secondary circuit to be rated SELV, in order for the load to be SELV. A common practice used with non-SELV secondary circuits to ensure electrical safety is to employ a grounded conductive housing enclosure, meeting established material and structural requirements, suitable for making bare conductors in the secondary exclusive of its output terminals inaccessible to an operator. Satisfying an isolation requirement of a non-SELV secondary circuit in order to have its output terminals and output load rated SELV imposes additional manufacturing costs and physical space requirements upon the system design, than would be the case where the secondary circuit is classified SELV. An advantage for an electrical system due to having secondary circuits rated SELV would therefore result in more favorable TCO analysis, in cases where it is a requirement that the load must be SELV. A further advantage for an electrical system, which is due to having higher secondary circuit efficiency, would result in less costly cooling apparatus, fixturing apparatus and housing apparatus, therefore lower cost to manufacture electrical system with subsequently more favorable TCO analysis being made possible. 
         [0013]    Transformers are useful for meeting a requirement of secondary circuits to be DC galvanically isolated from hazardous working voltages on primary conductors. Standards described herein define specific classes of insulation as being ‘functional’, ‘basic’, ‘supplemental’, ‘double’, or ‘reinforced’; and further describe substituting a grounded enclosure as an option in lieu of a transformer&#39;s supplemental insulation. The transformer construction may employ insulation that is classified as ‘functional insulation’. ‘Functional insulation’ does not provide protection against electric shock, or provide safety, it being assumed to possibly have small defects. ‘Basic insulation’ does provide basic protection against electric shock, but does not provide safety. ‘Supplementary insulation’ also provides basic protection against electric shock, but does not provide safety, however may be used together with basic insulation so that the insulation system comprising both basic and supplementary insulation is classified as ‘double insulation’, which does provide electrical safety protection under normal conditions or in the event of any single fault. ‘Reinforced insulation’ is a single-insulation system equivalent to double insulation in providing electrical safety protection. Other requirements for ELV and SELV classification such as minimum distances for creepage and clearance, insulation temperature class and maximum allowed hot spot temperature, and more, are further specified in the criteria herein described. For a secondary circuit to be classified as SELV when it is magnetically coupled through any transformer(s) to a primary circuit, besides having said maximum limits on its secondary voltage magnitudes it is required that the transformer insulation system be either ‘double’ or ‘reinforced’ type. It is possible to substitute a protective earth shield, comprising a conductive grounded enclosure, in place of ‘supplementary’ insulation and, together with ‘basic’ insulation, satisfy SELV criteria for an insulation system. Circuits so classified ELV or SELV must not have working voltage magnitudes which exceed limits given in relevant standards: for example, 42.4 V AC; or 60 V DC. One advantage of having a circuit classified SELV instead of ELV is that an operator may be permitted safe unrestricted access to its bare circuit components. 
         [0014]    Another classification which describes limited exposure levels for voltages in order to address electrical safety hazard concerns is that of ‘Telecommunications Network Voltage’ (TNV), where the normal operating voltage magnitudes may not exceed, for example, 71 V AC or 120 V DC, with an additional condition that the operator-accessible contact area is limited only to the surface of an exposed connector pin. Voltage magnitudes may be somewhat greater for limited time durations, as further described in industry-accepted relevant extant standards. 
         [0015]    It would represent an advancement to the art if a means were provided to those of ordinary skill in the art for choosing and utilizing an optimal power converter topology, or class of topologies, which allows simultaneous improvement to secondary circuit efficiency and reduction in secondary circuit working voltage magnitudes. In order to proceed with developing a framework within which to explore how working voltages are imposed in secondary circuits, towards a goal of seeking methods to limit those voltage magnitudes reliably in the context of electrical safety, it is essential to understand the difference in behavior between impedances differentiating between those that are voltage-compliant and those that are current-compliant, and to understand how the impedance of a secondary circuit may be compliant with compatible sourcing behavior of the primary circuit from which it receives its power. It is also essential to understand the relationship between output load voltage magnitude and secondary circuit working voltage magnitude levels in order to increase secondary circuit efficiency through higher load voltage magnitude levels, while promoting secondary circuit electrical or related environmental safety through lower working voltage magnitude levels. 
         [0016]    It should be understood that power converters are often manufactured and made available for sale to the market without attached loads. To increase generality of this description, the terms ‘load voltage’, ‘output voltage’, and ‘output terminal voltage’ may be used to essentially signify the same differential voltage, said differential voltage appearing at the output terminals of the power converter whether those terminals are real or virtual, and whether the power converter is supplying an external load, an internal load, or is unloaded. 
         [0017]    Many SM electrical power converters employ transformers to provide DC galvanic isolation between their input, herein called primary in the case of connection to primary circuits connected directly to the mains or other sources having hazardous voltage levels, and their output, herein called secondary; and in addition transformers perform power transformation from one set of current and voltage variables received as input on their primary into another which they produce as output on their secondary. AC current and AC voltage are received as inputs by the DC galvanically isolating transformer due to their generation through the forcing function actions of an primary AC power stage, generally involving electronic power switches which are controlled to be either on, or off, and cycled continuously to produce a periodic voltage waveform. A capacitor may be connected in series between this periodic voltage waveform, which may include a DC component, and the input to the primary of the transformer. One purpose of the capacitor is to allow higher frequency components to conduct but to block DC components from reaching the primary of the DC galvanically isolating transformer. The secondary circuit provides rectification of the AC current that sources from the transformer output, said rectification introducing DC components into the rectified current. Additionally, in one class of topologies a filtering function is generally employed using a series inductor and a shunt capacitor connected in the secondary circuit, which results in achieving a low-pass function on the power converter output voltage and current frequency components. In another class of topologies, only a shunt capacitor may be connected in the secondary circuit for filtering purposes. Where both AC components and a series electrically connected filter inductor are present in the secondary circuit, the working voltage maximum magnitude in the secondary circuit can significantly exceed the voltage magnitude of the secondary circuit&#39;s output terminals. This secondary circuit which includes an inductor forms a voltage-compliant load to the primary circuit, and is compliant with a primary circuit that behaves as a current-compliant voltage source (CCVS). 
         [0018]    It is understood by those of ordinary skill in the art of isolated power converter design that a DC galvanic isolation barrier must exist between primary and secondary circuits of isolation converters, and these barriers must adopt effective isolation means for each interface where signals or power passes between the primary and the secondary, including but not limited to feedback signals, fault signals, and control signals, as appropriate to each converter design. 
         [0019]    A voltage-compliant current source (VCCS) can be realized through the behavior of an inductor. Inductor current cannot change instantaneously and inductor differential voltage may vary to be compliant with behavior of the circuit to which it connects. A CCVS can be realized through the behavior of a capacitor. Capacitor differential voltage cannot change instantaneously and the capacitor current may vary to be compliant with behavior of the circuit to which it connects. The characteristic of a variable type not being able to change instantaneously is termed herein as a source of that variable type. The characteristic of a variable type that is able to change instantaneously is termed herein as being compliant of that variable type. 
         [0020]    SM power converter circuits can employ a class of VCCS topologies with full wave rectification, a class of VCCS topologies with half wave rectification, or a class of CCVS topologies, where the VCCS and CCVS designations refer to behavior of the primary power circuit acting upon the secondary power circuit. In all topologies, a rectifier is series electrically connected with the output load, and installed before any secondary circuit series inductor or secondary circuit shunt capacitor, and installed after the transformer secondary terminals, for the purpose of rectifying an AC current without DC current on its input into a DC current with possible AC current components, and allowing the shunt capacitor to subsequently produce a DC voltage component on its output with possible AC voltage components. 
         [0021]    The more traditional class of topologies involve a primary power circuit which acts as a CCVS, and the rectifier-low-pass-filter circuit combination connected in the secondary circuit comprises series rectifier followed by series inductor and shunt capacitor, which may produce a nearly DC voltage waveform at the secondary circuit output due to the averaging function the filter performs, retaining the DC component of rectified AC current and attenuating the AC components of filtered output voltage. 
         [0022]    A CCVS topology does not have substantial inductance series electrically connected with the primary of the transformer, and instead has a filter inductor series electrically connected with the secondary of the transformer, where it allows the transformer secondary to behave as a CCVS, compliant with the load characteristics of imposed current behavior by the relatively high impedance of the secondary filter inductor. A special category of CCVS topologies is a phase-shift modulated quasi-resonant zero voltage switch (ZVS) topology, which, besides employing a secondary circuit connected filter inductor as do other CCVS topologies, has only as much inductance intentionally connected in the primary, either as a discrete element, stray and leakage inductances, or some combination, to provide the small amount of energy, in the form of voltage-compliant current sourcing, required in order to effect so-called soft resonant transition of the switches from one state to another thereby reducing the hard-switching power losses which would otherwise result. The inductance employed in the primary circuits of these quasi-resonant schemes is insignificant in relation to that employed in their secondary circuits, said secondary filter inductance performing a low-pass filtering function in conjunction with a secondary shunt capacitor. In the CCVS class of topologies, including these quasi-resonant ZVS topologies just described, the maximum operational voltage magnitude in the secondary side circuit may be significantly higher than the maximum output load voltage magnitude. Utility of the CCVS class of topologies does allow for higher efficiency through higher output load voltage values, but at a cost of imposing working voltage magnitude values in the secondary circuit that are substantially higher than the output load voltage magnitude, and which at relatively low output voltage levels may result in hazardous voltage levels in the secondary circuit. 
         [0023]    In any topology of the VCCS with full wave rectification class an inductor of significant value may be series electrically connected to the transformer primary. A capacitor is also electrically connected in the primary in series with the inductor. In resonant topologies of the VCCS with full wave rectification class the placement of a significant inductance in electrical series connection to the primary of the transformer, in addition to a series electrically connected capacitor and resulting resonant behavior, is motivated in some instances, at least in part, by the desire to capture an advantage of reducing the switching power losses associated with the primary switches that create the AC waveform for the transformer. A rectifier which produces a DC component on its output by rectifying an AC waveform on its input is necessary to be series electrically connected with the secondary of the transformer, as DC components cannot be passed through the transformer from its primary to its secondary. In this case of the VCCS with full wave rectification class of topologies the inductor series electrically connected in the primary circuit and being excited by a voltage waveform forcing function generated by cyclic on and off actions of the switches, conducts only AC components as ensured by the DC blocking behavior of the series electrically connected capacitor. The inductor attenuates higher frequency harmonics to a greater degree than lower frequency harmonics, in so doing acts also as a low pass filter. The primary inductor and its effect as a low pass filter, as well as the primary capacitor and its effect as a high pass filter, together acting as a band-pass filter, appear in equivalent series electrical connection to the output load, and in equivalent shunt connection to the secondary capacitor, when the secondary rectifier, secondary capacitor, and output load are reflected analytically from the secondary to the primary side of the transformer. The secondary rectifier will introduce a DC on its output, or load side, from the AC of the band-pass filter on its input, or transformer side. Acting together with the secondary rectifier and secondary shunt capacitor, the inductor on the primary performs a low-pass filtering operation that produces primarily DC on the output terminals. 
         [0024]    This primary circuit with its series electrically connected inductance and series electrically connected capacitance in VCCS topologies behaves resonantly when excited by forcing function frequencies near its natural frequency/ies. In the case of an inductor series electrically connected to the primary of the transformer of VCCS topologies, it is desired to allow waveforms at the forcing function switching frequency/ies to pass for the purpose of providing an AC power source to the transformer&#39;s input, and at a frequency or range of frequencies for which the transformer was designed; while in the contrasting case of a filter inductor series electrically connected to the secondary of the transformer of CCVS topologies, it is desired instead by its use in conjunction with the secondary shunt capacitor only to reduce high frequency components, preserving only the DC component from the secondary rectifier output. 
         [0025]    Summarizing the filter behavior then, the secondary shunt capacitor in the VCCS with full wave rectification class of topologies attenuates high frequency harmonics as it does in the case of the CCVS class of topologies, but unlike in the CCVS class of topologies must work as a filter element in conjunction with the effective primary inductance seen as reflected analytically from the primary to the secondary. The low pass filter creating a DC output for the resonant class of VCCS with full wave rectification topologies comprises primary inductance acting as filter inductor, secondary full wave rectifier, and secondary shunt capacitor. The low pass filter creating a DC output for the CCVS class of topologies comprises secondary full or half wave rectifier, secondary filter inductor, and secondary capacitor. 
         [0026]    It is possible due to resonance to obtain higher working voltages within elements of primary resonant circuits in VCCS topologies than those imposed by the forcing function on the inputs of these circuits. This is a preferable effect to an alternative approach of CCVS topologies which imposes higher working voltage in a secondary circuit, with respect to electrical or electrically related environmental safety of secondary circuits. 
         [0027]    An understanding of the VCCS with full wave rectification class of topologies can become slightly more complex in the case of a resonant topology such as one referred in the literature to as an ‘LLC’ wherein a second inductor in shunt with the transformer primary performs an additional role, acting in shunt with the magnetizing inductance of real-world transformers, to promote in the primary circuit greater circulating current than otherwise, which causes the total primary circuit circulating current to exceed that amount necessary for supporting the required reflected load current and magnetizing current of a typical transformer&#39;s primary. As this shunt inductor along with the magnetizing inductance of the transformer primary acts in conjunction with the primary series inductance in determining the current being sourced to the transformer primary throughout the entire operational period, in a role supporting resonant behavior of the primary circuit, it forms an integral part of the band-pass filter inductance as described previously. 
         [0028]    A resonant inductance that is series electrically connected in the primary circuit becomes a VCCS which acts upon the transformer primary. Behavior of the switches in the primary circuit along with that of the primary capacitor connected in series between the forcing function generated by the switches and the primary series inductance act to create only AC voltage components on the input of the inductor. The differential voltage of the primary series inductance is clamped to the difference between the primary voltage of the transformer, and the sum of forcing function voltage plus the differential voltage of the series electrically connected capacitor. Any DC voltage component created by the switches is prevented by behavior of the capacitor from reaching either the primary series inductor or subsequently the transformer&#39;s primary. The voltage impressed on the transformer&#39;s primary due to the forcing function and primary resonant circuit consequently is AC, and its magnitude is allowed by the voltage-compliance of the primary series inductance to be clamped through the full wave rectifier(s) of its secondary to the reflected magnitude of the power converter&#39;s output terminal voltage plus that of reflected magnitudes of forward voltage drops of the rectifier(s) and other secondary series impedances; where voltage polarity of the transformer is in a direction determined by current flowing through it resulting from the changing current levels in the primary series resonant, primary shunt magnetizing, and any primary shunt inductances, so that due to the resulting current and voltage polarities only positive power is input to the transformer primary. Due to voltage-compliance of the transformer&#39;s secondary winding(s), and the current-compliance of the secondary circuit connected to it, the transformer output will not impose any voltage magnitude level upon the secondary circuit which exceeds the power converter&#39;s output terminal voltage magnitude by more than is necessary to overcome forward voltage drops in the forward biased rectifier and other series impedances of the secondary circuit. The maximum working voltage magnitude in the secondary circuit will therefore be clamped by the secondary rectifier(s) over the full cycle to not exceed the power converter&#39;s output terminal voltage magnitude by any significant amount, assuming the output voltage forward drop is significantly greater than the secondary rectifier forward voltage drop(s) plus that due to the influence of series electrically connected secondary impedances, resistances, or other devices. 
         [0029]    The VCCS with half wave rectification class of topologies will be mentioned briefly at this point, as it has not been discussed earlier. Without the benefit of full wave rectification, the secondary of the transformer does not have its maximum voltage magnitude clamped to the secondary circuit voltages during the non-conducting half cycle of the rectifier(s). The maximum voltage magnitude of the secondary transformer voltage can rise therefore to its maximum compliance level, imposing this voltage on the input of the non-conducting rectifier(s) installed in the secondary circuit. An intrinsic advantage of limiting secondary maximum voltage magnitudes does not result by using the VCCS with half wave rectification class of topologies. The advantage can be regained in the case where a voltage clamp is employed to ensure the non-conducting half cycle voltage magnitude does not exceed the desired limit. 
         [0030]    In the example given of a luminaire, it would be a practical maintenance advantage for the operator to be able to exchange that portion of the system containing only the LED subsystem without being exposed to hazardous potentials, or risk of electric shock. In the example where an operator would have access to an LED subsystem and secondary circuit to which it connects, these would be classified SELV for the purpose of addressing the requirement for electrical safety against electric shock hazard. 
         [0031]    Based upon this framework of impedances and filters just developed to understand the relevant behavioral differences between CCVS class, VCCS with half wave rectification class of topologies, and VCCS with full wave rectification class of topologies, two examples are now given for comparison where in order to optimize for secondary circuit efficiency through means of using the highest feasible output voltage for the case of a secondary circuit which is to be classified as SELV, it must be assured through design, either inherently, by active means, or both, that working voltages in the secondary shall not exceed 42.4 V AC or 60.0 V DC under normal conditions or single fault conditions. The AC voltage peak produced by the transformer secondary is the largest magnitude of all voltages present in the secondary circuit of SM topologies considered herein since the maximum DC voltage magnitude does not exceed the maximum AC peak voltage magnitude; so the design must limit secondary working voltages to 42.4 VAC, which corresponds to a sinusoidal waveform with 60.0 V peak, on the transformer secondary for those circuits to be classified SELV. 
         [0032]    In a first example one assumes the total forward voltage drop of all series electrically connected elements, exclusive of any inductive element, between the transformer secondary and the power converter output terminals are equal to 2.4 V, where an arrangement of secondary full wave current rectification elements is employed which imposes forward voltage drops of two series rectifiers at 1.2 V each, and where the topology to be used for power conversion is chosen from the more prevalent CCVS class of topologies; and one further assumes that a minimum duty cycle of 0.3 may occur, signifying the pulse width minimum limit is 30% of the ideal maximum full pulse width, then due to the voltage averaging effect of the CCVS&#39;s secondary inductor the load voltage in the ideal case will be the product of the duty cycle, 0.3, and the transformer secondary voltage, 60.0 V, minus the secondary circuit&#39;s forward voltage drops, 2.4 V: 15.6 V. This would produce secondary circuit efficiency of the output voltage, 15.6 V, divided by the sum of the output voltage, 15.6 V, and the forward voltage drops, 2.4 V: 0.87. An over-voltage condition could still result in the secondary circuit under a fault condition, as in one case where the mains supply voltage were to be too high, unless the higher working voltage in the secondary can be prevented by an effective fast-acting supplemental protection in the form of a circuit for over-voltage detection which acts to sense and limit secondary working voltage maximum levels. 
         [0033]    In a second example, one assumes in the previous example that the topology to be used for power conversion is instead chosen from among the VCCS with full wave rectification class of topologies described herein, and which therefore does not include a secondary inductor capable of performing voltage averaging, and which for the purpose of illustration does include a full bridge rectifier in its secondary, and therefore that the current-compliant secondary circuit does not act by performing a voltage averaging function on the periodic waveshape resulting from the rectified transformer secondary voltage, as in the case of the CCVS class of topologies, then the load voltage will be the transformer secondary peak voltage, 60.0 V, minus the total forward voltage drops of 2.4 V: 57.6 V. This would produce secondary circuit efficiency equal to the output voltage, 57.6 V, divided by the sum of the output voltage, 57.6 V, and the forward voltage drops, 2.4 V: 0.96. This example uses the VCCS with full wave rectification class of topologies to produce secondary circuit efficiency calculated at 9% greater than that calculated in the first example using CCVS class of topologies. 
         [0034]    Further, it is necessary in the case of the VCCS with full wave rectification class of topologies as in the CCVS class of topologies, that in order to satisfy criteria ensuring electrical safety of an SELV secondary circuit is maintained in the event of a single fault, there is a requirement that should the control over the primary malfunction, the transformer secondary voltage magnitude must be prevented from becoming higher than planned by design in the given case of an intended 57.6 V load voltage. A single fault in this extreme case could result in a voltage excursion of the transformer&#39;s secondary which immediately violates the maximum voltage magnitude limit, unless the higher working voltage magnitude can be prevented by an effective fast-acting supplemental form of protection in the form of a circuit for over-voltage detection which acts to sense and limit secondary working voltage levels. In practice, some design margin would be allowed for by designing for a slightly lower output voltage than the theoretical maximum, which would accommodate the delay of the protection circuit. 
         [0035]    In both the first example of CCVS class of topologies and the second example of VCCS with full wave rectification class of topologies, the criteria for SELV would necessitate an effective protection circuit which acts to sense and limit secondary working voltage levels; but the second example, due to its normally and inherently lower levels of maximum working voltage magnitudes at any given power converter output terminal voltage, continues to offer new utility of higher secondary circuit efficiency while continuing to satisfy criteria for low-voltage classification; or, more generally, having higher secondary circuit efficiency with an advantage of lower working voltage magnitudes in secondary circuits. Even if the required criteria were for ELV classification instead of SELV classification, the second example would continue to offer new utility through higher secondary circuit efficiency resulting from higher load voltage, while imposing lower secondary working voltage maximum magnitudes. By using these two topology examples for both SELV or ELV secondary circuits, one may design a load voltage in the case of the second topology example which is greater than in the case of the first topology example, but less than the maximum ideally achievable as described in the second example, so that an additional advantage resulting from the VCCS with full wave rectification class of topologies over the CCVS class of topologies is that they would have simultaneously lower working voltage magnitudes in the secondary and higher secondary circuit efficiency. 
         [0036]    It should be understood that the application example given of an LED luminaire is for illustrative purposes, it being a relevant actual case; and using this example does not imply or intend any limits to the scope of applicability for which exists such requirements for new utility of a class of power converter topologies herein described as being VCCS with full wave rectification. It should be further understood that in the description of how efficiency is to be calculated there should be included a usually small additional current component which conducts through the rectifier but does not conduct through the output load, due to a need to generate internal bias power to satisfy requirements of secondary control circuits. This additional current component has been ignored in the interest of simplicity of illustration, and this simplification does not imply or intend to limit the scope of applicability for which exists such requirements for new utility of a power converter as herein described. 
         [0037]    A third example simply recognizes the advantage of lower magnitude of working voltages in secondary circuits, without attempting to satisfy either ELV, SELV, or other limited-voltage secondary circuit constraints. A high voltage battery charger system may be incorporated into an electric or a hybrid electric automobile, wherein power converter output terminal voltage would at relatively high magnitude to properly charge the high voltage battery load. This imposes insulation and isolation requirements upon the design of the power converter charger in order to protect the operator from coming into contact with hazardous voltages. The high voltage power converter is more easily manufactured for a lower cost, and with greater levels of performance and safety assurance, for power converters with isolated secondaries having lower levels of working voltage magnitudes. In this example the VCCS with full wave rectification would have greatly reduced secondary working voltage magnitudes when compared with the CCVS class of topologies. Secondary circuit efficiency may also be improved to a minor degree for the high voltage power converter designed using VCCS, owing to the fact that high voltage rectifiers have typically larger forward voltage drops, and owing to the inability of low forward voltage drop Schottky diodes to be employed, so the primary resulting benefit would be in reducing cost of manufacture and reducing potential safety hazards through reduced insulation and isolation requirements, and the secondary benefit may be in improved secondary efficiency. 
         [0038]    Finally, it is observed that the invention may be well suited to applications where reduction in package size and weight would represent a benefit, such as for automotive applications, and would be especially well suited to exo-atmospheric applications where insulation and isolation requirements are even more imposing on package size and weight, and where for instance the benefit of reduction in package size and weight would be of high value. 
       SUMMARY OF THE INVENTION 
       [0039]    The inventor has found that a need exists to provide working voltage magnitude values optimized at lower levels in power conversion secondary circuits to achieve benefits for power converters of reduced cost of manufacture, reduced size, improved reliability, or reduced inherent risk of safety hazard. 
         [0040]    The inventor has also found that a need exists to provide greater secondary circuit power conversion efficiency through designing higher output load voltage magnitude values, while simultaneously promoting safety for operators through limiting working voltage magnitude values in power conversion secondary circuits to levels deemed safe for human physical contact, or to levels which would not ignite a fire or explosion in certain classified hazardous environments. 
         [0041]    The inventor has further found that a need exists for new utility of a class of DC-to-DC electrical power converters that optimally addresses simultaneously improving secondary circuit power conversion efficiency and limiting working voltage magnitude values in power conversion secondary circuits to levels deemed safe for human physical contact, or to levels which would not ignite a fire or explosion in certain classified hazardous environments. 
         [0042]    The inventor has further yet found that a need exists for new utility of a class of DC-to-DC electrical power converters to increase market adoption of energy efficient systems due to more favorable TCO analysis based upon lower operating costs and lower manufactured cost; where secondary circuits have lower operating costs facilitated by higher efficiency, and the lower manufactured cost facilitated by lower working voltage magnitudes, and higher efficiency. 
         [0043]    It is an object of this invention to provide innovative utility of a class of DC-to-DC power conversion topologies to achieve in secondary circuits unexpected benefits of, and due to, optimization for lower levels of working voltage magnitude values. 
         [0044]    It is yet another object of this invention to provide innovative utility of a class of DC-to-DC power conversion topologies to achieve in secondary circuits unexpected benefits of, and due to, greater power conversion efficiency and simultaneously optimizing for lower levels of working voltage magnitude values. 
         [0045]    It is further yet another object of this invention to provide innovative utility of power conversion technology through employing a VCCS with full wave rectification class of topologies, where converters utilizing VCCS topologies may sometimes be referred to as current-fed converters, to optimize for greater power conversion efficiency through higher output load voltage magnitudes while simultaneously limiting increase to the working voltage magnitude values in secondary circuits to only small increase above the voltage magnitude of the power output terminals. 
         [0046]    This and other objects are also achieved by providing a means to limit maximum working voltage magnitudes in secondary circuits connected to the output of an AC source so they do not exceed the voltage magnitude of the power output terminals beyond that required to overcome secondary rectifier forward voltage drop(s) plus forward voltage drops due to the influence of effectively stray impedance(s), resistance(s), current monitor(s), or other device(s) series electrically connected between the input to the secondary circuit and the power output terminals, through which power converter output current must flow. 
         [0047]    The subject invention may be implemented by series electrically connecting an inductor of appropriate inductance value in the power converter primary circuit supplying power to the input of a DC galvanically isolating transformer, or by incorporating inductance of appropriate value into the DC galvanically isolating transformer primary and secondary as leakage inductance, or both; and by not allowing any substantial amount of inductance to be series electrically connected in the secondary power circuit between the input of the secondary power circuit and its secondary capacitor, exclusive of said transformer secondary. The details of how large the value of inductance and value of primary series capacitor in the primary circuit should be are dependent on the particularities of each design such as regarding input voltage range, output power and voltage range, and specific topology chosen from among the class of VCCS with full wave rectification topologies. In the case of one such topology known as ‘LLC’ that was chosen for the preferred embodiment of this invention, details can be found in a paper, publically available on the date of this filing, by Hang-Seok Choi, entitled “Application Note AN-4151, Half-bridge LLC Resonant Converter Design Using FSFR-series Fairchild Power Switch (FPS™)”, published October 2007 as Revision 1.0.0 by Fairchild Semiconductor Corporation, as well as from other publically available sources. Those of ordinary skill in the art of power converter design will be able to follow and apply this application note, or other instructions available from several publically available sources. 
         [0048]    Implementing the subject invention requires also that a full wave rectifier arrangement be electrically connected in the secondary circuit following the transformer secondary, as a means to full wave rectify the transformer secondary current. Operation of the full wave rectifier requires its conduction over the full cycle in order to clamp the voltage compliant secondary of the transformer so its voltage magnitudes do not at any time during its cycle exceed the maximum magnitude value of the voltage of the power output terminals plus said forward voltage drop(s). 
         [0049]    Implementing the subject invention further requires that either a secondary capacitor or voltage clamp be electrically shunt connected in the secondary circuit after the full wave rectifier, or that a load be attached to the power output terminals which establishes a maximum voltage magnitude such as for the case of a load comprising either a battery, an LED, or a voltage clamp. The input impedance of the secondary circuit is required to be current-compliant, which may be aided by the placement of this capacitor, said voltage clamp, or said output load, and lack of significant inductive elements in series electrical connection between the secondary of the transformer and this capacitor, said voltage clamp, or said output load. Inductive elements are significant if during the normal operation of the converter over its usual range of frequencies they produce voltage drops that are great enough that they must be considered in designing an appropriate level of load voltage which would limit the maximum working voltage magnitude to an intended value. The secondary circuit must be designed to withstand maximum working voltage magnitudes only modestly greater than the voltage magnitude of the power output terminals as necessary to also overcome secondary rectifier forward voltage drop(s) plus said forward voltage drop(s) due to the influence of series electrically connected effectively stray impedance(s), resistance(s), current monitor or other device(s) through which load current must conduct between the transformer secondary and either the secondary capacitor, said voltage clamp, or said output load, whichever is electrically connected in an electrically conductive path to the transformer secondary that has the lower cumulative forward voltage drop along the conductive path. 
         [0050]    Implementing the subject invention, in the event regulation of voltage occurs by remote voltage sense at the load terminals, also requires that impedances through which power converter output current must flow between secondary shunt capacitor, or voltage clamp, in the secondary circuit and power output terminals must be substantially non-inductive. Some implementations may install a current monitor device between the capacitor, or voltage clamp, and the output terminals, which may impose additional impedance in series between the transformer secondary and the power output terminals. It is necessary that this and other impedance(s) located between the transformer secondary and the power output terminals impose no greater than modest forward voltage drop(s), if the resulting working voltage maximum magnitudes be no more than modestly greater than the power output terminal voltage magnitude as necessary to overcome secondary rectifier forward voltage drop(s) plus forward voltage drop(s) due to the influence of series electrically connected effectively stray impedance(s), resistance(s), current monitor or other device(s) through which load current must conduct between the transformer secondary and the power output terminals. 
         [0051]    The impedance between the power output terminals and the output load is assumed to be nil, however should it be non-zero then the relationship between the working voltage maximum magnitudes in the secondary circuit and that of the output load is that the working voltage maximum magnitude will not exceed output load voltage magnitude by more than necessary to include forward voltage drop in impedance between output terminals and power output load, in addition to previously mentioned secondary rectifier forward voltage drop(s) plus forward voltage drop(s) due to the influence of series electrically connected effectively stray impedance(s), resistance(s), current monitor or other device(s), through which load current must conduct between the transformer secondary and the output load. 
         [0052]    Implementing the subject invention in the case of also satisfying criteria for safety protection additionally requires insulation and isolation methods and materials of nature and design that are well understood by those of ordinary skill in the art of power converter design. 
         [0053]    Implementing the subject invention in the case of also satisfying criteria for safety protection additionally under a specified number of simultaneous fault conditions requires inclusion of fault detection and fault limit circuits of nature and design that are well understood by those of ordinary skill in the art of power converter design. 
         [0054]    Implementing the subject invention does not require regulation of output load voltage or current, or detection of faults. Load regulation and fault detection are generally done, as in the case of the preferred embodiment, to satisfy additional criteria beyond those for functional insulation, for redundant protection means to ensure electrical safety, or to safeguard the load. 
         [0055]    With the implementation as described in this summary, higher output load voltages may now be regulated for SELV or ELV secondary circuits through means of this new utility employing the VCCS with full wave rectification class of topologies, than would be otherwise have been possible using the CCVS class of topologies, for the purpose of achieving the benefits of greater secondary circuit efficiency, smaller packaging size and weight, and lower cost of manufacture. Greater secondary circuit power conversion efficiency results through reduction to percentage of power loss, said loss including that which occurs due to output load current conducting through the transformer&#39;s output circuit rectifier forward voltage drop(s). 
         [0056]    With the implementation as described in this summary for any given output voltage magnitude, lower secondary circuit maximum working voltage magnitudes results through means of this new utility employing the VCCS with full wave rectification class of topologies, than would be otherwise possible with the CCVS class of topologies, for the purpose of achieving benefits of reduction in the risk of safety hazard due to secondary circuit voltage magnitude, smaller packaging size, or lower cost of manufacture. 
         [0057]    Further scope of applicability of the present invention will become apparent from a review of the detailed description and accompanying drawings. It should be understood that the description and examples, while indicating preferred embodiments of the present invention, are not intended to limit the breadth of the invention since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0058]    The present invention will become more fully understood from the detailed description given below, together with the accompanying drawings which are given by way of illustration only, and thus are not to be construed as limiting the scope of the present invention. In the drawings: 
           [0059]      FIG. 1  shows a simplified schematic circuit diagram of a method of power conversion, herein also referred to as an power converter circuit, according to a preferred embodiment of the present invention. 
           [0060]      FIG. 2 , which is a continuation of  FIG. 1 , shows additional details for implementing the preferred embodiment which relate to the power converter circuit&#39;s plant function. 
           [0061]      FIG. 3 , which is a continuation of  FIG. 2 , shows additional details which relate to the power converter circuit&#39;s actuator, control, sense and feedback functions, for implementing the preferred embodiment. 
           [0062]      FIG. 4 , which is a continuation of  FIG. 3 , shows additional details which relate to the power converter circuit&#39;s fault detection, and fault limit control functions, for implementing the preferred embodiment. 
           [0063]      FIG. 5 , which is a continuation of  FIG. 4 , shows additional details relating to the power converter circuit&#39;s supplementary fault detection, supplementary fault limit control, and supplementary sense and feedback functions, for implementing another embodiment. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0064]    The following description of the preferred embodiments refers to a power conversion circuit and method which are useful for improving efficiency of conversion of power for use by a means of power consumption, herein also referred to as a load, and reducing maximum magnitude working levels of across-variable, herein also referred to as working voltages, of means of secondary sources, herein also referred to as secondary circuits. The load can be any type or combination of circuit elements capable of supporting the designed-for output voltage level. 
         [0065]    It should be understood that the preferred embodiment of the power conversion circuit employs an ‘LLC’ topology which provides across-variable-compliant through variable, herein also referred to as voltage-compliant current, sourcing of power input to the secondary circuit, and that there are several topologies available for this purpose of providing a voltage-compliant current source at the means of functional connectivity, herein also referred to as the input, to the secondary circuit; and that the ‘LLC’ topology has several embodiments exploiting how means of leakage energy-field coupling, herein also referred to as leakage inductance, and magnetizing inductance of the AC power energy-field coupling, herein also referred to as the power transformer may eliminate or offset a need for discrete means of energy-field coupling, herein also referred to as inductors, unlike for the present instance in the case of the preferred embodiment for the sake of simplicity of illustration where series and shunt inductors are included as discrete elements and leakage and magnetizing inductances are ignored; and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of ‘LLC’ topology in this particular embodiment. 
         [0066]    It should be further understood that the preferred embodiment derives bias and control power for various internal supporting circuits, but that for the sake of illustrative simplicity the figures do not show the derivation or routing of bias and control power, taking advantage of an assumption that those of ordinary skill in the art of design of power converter circuits are well familiar with numerous techniques to derive bias and control power, including its provisioning of any needed DC through-variable direct means of functional connectivity, herein also referred to as DC galvanic, isolation as, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of not illustrating the derivation and use of bias and control power. 
         [0067]    It should be yet further understood that the preferred embodiment does not employ an intermediate primary power stage for the purpose of controlling input power factor, or for reconfiguring the primary bridge rectifier along with suitable detection and control to accommodate different mains supply voltage levels, and that there are possible embodiments which would include some or all of these features, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of not employing an intermediate primary stage for the purpose of either reconfiguration of primary bridge rectifier or control of power factor. 
         [0068]      FIG. 1  shows a simplified schematic circuit diagram of method of power conversion, herein also referred to as power converter circuit  1 , according to a preferred embodiment of the present invention. Power converter circuit  1  has means of functional connectivity to line input, herein also referred to as line terminal  1   a;  and to means of functional connectivity to neutral input, herein also referred to as neutral terminal  1   b;  and to means of functional connectivity to ground input, herein also referred to as ground terminal  1   c;  and to means of functional connectivity to positive differential output, herein also referred to as positive differential output terminal  1   d;  and to means of functional connectivity to negative differential output, herein also referred to negative differential output terminal  1   e.  Said positive differential output terminal  1   d  and said negative differential output terminal  1   e  are referred to in the claims herein as a set, termed ‘power output terminals’ or equivalently ‘means of functional connectivity to output of power conversion method’. 
         [0069]      FIG. 1  also shows accessibility to means of functional connectivity, herein also referred to as terminals, for mains power and ground.  FIG. 1  also shows a means of power consumption, herein also referred to as a load, illustrating an application. 
         [0070]    The embodiment of the present invention shown in  FIG. 1  includes access to mains power supply distribution  20  and installation facility  30 . The mains power supply distribution  20  has line terminal  20   a,  and neutral terminal  20   b.  The installation facility&#39;s  30  has ground terminal  30   a.    
         [0071]    The embodiment of the present invention shown in  FIG. 1  includes the application of electrically conductive cables  10 ,  11  and  12 . Electrically conductive cable  10  has terminals  10   a,    10   b.  Electrically conductive cable  11  has terminals  11   a,    11   b.  Electrically conductive cable  12  has terminals  12   a,    12   b.  Electrically conductive cable&#39;s  10  terminal  10   a  connects to mains power supply distribution&#39;s  20  line terminal  20   a,  and electrically conductive cable&#39;s  10  terminal  10   b  connects to power converter circuit&#39;s  1  line terminal  1   a.  Electrically conductive cable&#39;s  11  terminal  11   a  connects to mains power supply distribution&#39;s  20  neutral terminal  20   b,  and electrically conductive cable&#39;s  11  terminal  11   b  connects to power converter circuit&#39;s  1  neutral terminal  1   b.  Electrically conductive cable&#39;s  12  terminal  12   a  connects to installation facility&#39;s  30  ground terminal  30   a,  and electrically conductive cable&#39;s  12  terminal  12   b  connects to power converter circuit&#39;s  1  ground terminal  1   c.    
         [0072]    Mains power supply distribution  20  is the source of input power to the power converter circuit in this preferred embodiment. Installation facility  30  is the contact for safety earth grounding provided by the facility wherein the power converter circuit is located. 
         [0073]    It should be understood that the preferred embodiment employs a single point of grounding at the power converter, power converter circuit&#39;s  1  ground terminal  1   c,  and that other possible embodiments would employ multiple points of grounding at the power converter, such as in the case of an IS power converter circuit which employs two independent points; or there may be no points of grounding, as would be the case where grounding is not applicable, such as with independent input energy storage represented by a battery; and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of a single independent point of grounding the power converter circuit. 
         [0074]    It should be understood that the preferred embodiment employs power input from a primary mains supply that is single phase, and that there are other possible embodiments which separately or interchangeably employ power inputs which are single phase or polyphase AC, non-mains inputs, or DC, but no more than one input supplying power at any one moment, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of either primary mains or single phase as the power input. It should be further understood that the preferred embodiment employs availability of an installation facility&#39;s  30  ground terminal  30   a,  and that there are other possible embodiments which do not employ a facility&#39;s  30  ground terminal  30   a,  or any ground terminal  30   a  at all, or any facility  30  at all, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of employing a facility ground terminal. 
         [0075]    The embodiment of the present invention shown in  FIG. 1  includes a means of primary power source, herein also referred to as primary power circuit  40 . Primary power circuit  40  also belongs to a larger set known as a primary circuit. The primary power circuit  40  has line means of functional connectivity to its input, herein also referred to as line input terminal  40   a;  neutral means of functional connectivity to its input, herein also referred to as neutral input terminal  40   b;  ground means of functional connectivity to its input, herein also referred to as ground input terminal  40   c;  and means of functional connectivity to its output, herein also referred to as output terminals  40   d,    40   e.  Primary power circuit&#39;s  40  line input terminal  40   a  connects to power converter circuit&#39;s  1  line terminal  1   a.  Primary power circuit&#39;s  40  neutral input terminal  40   b  connects to power converter circuit&#39;s  1  neutral terminal  1   b.  Primary power circuit&#39;s  40  line ground terminal  40   c  connects to power converter circuit&#39;s  1  ground terminal  1   c.    
         [0076]    Primary power circuit  40  obtains through-variable-compliant across variable, herein also referred to as current-compliant voltage, sourcing input power through its connections to power converter circuit&#39;s  1  line input terminal  1   a  and power converter circuit&#39;s  1  neutral input terminal  1   b,  and converts this power into the form of a voltage-compliant current source, which it produces as output power on means of functional connectivity, herein also referred to as output terminals of primary power circuit  40 , identified in  FIG. 1  as output terminals  40   d,    40   e.  Primary power circuit  40  also obtains electrical conductivity to safety ground through connection with power converter circuit&#39;s  1  ground terminal  1   c,  which it may used for purpose of filtering conducted electro-magnetic emissions away from injecting onto the power supply distribution  20 , shielding radiated electro-magnetic emissions to limit them from escaping the confines of a grounded enclosure, or providing through the connection of conductive ground to an electrically conductive enclosure of primary circuits one level of protection to an operator from electric shock due to the influence of hazardous voltages on the primary circuit. 
         [0077]    The embodiment of the present invention shown in  FIG. 1  includes a means of secondary power source, also referred to herein as secondary power circuit  60 , following the primary power circuit  40 . Secondary power circuit  60  also belongs to a larger set known as a secondary circuit. The secondary power circuit  60  has means of functional connectivity to inputs, herein also referred to as power input terminals  60   a,    60   b;  means of functional connectivity to ground input, herein also referred to as ground input terminal  60   c;  actuator one in-phase terminal  60   d,  actuator one reverse-phase terminal  60   e,  actuator two in-phase terminal  60   f,  actuator two reverse-phase terminal  60   g;  means of functional connectivity to positive differential output, herein also referred to as positive differential output terminal  60   h;  and means of functional connectivity to negative differential output, herein also referred to as negative differential output terminal  60   i.  Secondary power circuit&#39;s  60  input terminal  60   a  is connected to primary power circuit&#39;s  40  output terminal  40   d;  secondary power circuit&#39;s  60  input terminal  60   b  is connected to primary power circuit&#39;s  40  output terminal  40   e;  secondary power circuit&#39;s  60  input ground terminal  60   c  is connected to power converter circuit&#39;s  1  ground terminal  1   c  and primary power circuit&#39;s  40  line ground terminal  40   c.  Secondary power circuit&#39;s  60  positive differential output terminal  60   h  is connected to power converter circuit&#39;s  1  positive differential output terminal  1   d;  secondary power circuit&#39;s  60  negative differential output terminal  60   i  is connected to power converter circuit&#39;s  1  negative differential output terminal  1   e.  Said secondary power circuit&#39;s  60  positive differential output terminal  60   h  and said secondary power circuit&#39;s  60  negative differential output terminal  60   i  are referred to in the claims herein as a set, termed ‘secondary circuit output terminals’ or equivalently ‘means of functional connectivity to means of secondary power source output’. 
         [0078]    Secondary power circuit  60  presents through-variable-compliant, herein also referred to as current-compliant, input impedance on its input terminals  60   a,    60   b.  Secondary power circuit  60  obtains input power from a voltage-compliant current source through its input terminals  60   a,    60   b,  which power is provided by the primary power circuit&#39;s  40  output terminals  40   d,    40   e,  and conditions this power into the form of a current-compliant voltage source that it produces as output on secondary power circuit&#39;s  60  output terminals  60   h,    60   i.  Secondary power circuit  60  also obtains means of functional connection, herein also referred to as electrical conductivity to safety ground at installation facility&#39;s  30  ground terminal  30   a  through connection with power converter circuit&#39;s  1  ground terminal  1   c.    
         [0079]    It should be understood that the preferred embodiment includes one primary power circuit  40 , and one secondary power circuit  60 , yet another embodiment may include several primary power circuits operating simultaneously either in parallel, series, or series-parallel, in place of one primary power circuit  40 ; and yet another embodiment may include several secondary power circuits operating simultaneously either in parallel, series, or series-parallel, in place of one secondary power circuit  60 ; or that yet still another embodiment may include any combination of multiples of the herein described permeations of primary power circuits to the herein described permeations of secondary power circuits, or the herein described permeations of secondary power circuits to the herein described permeations of primary power circuits; or the division between primary power circuit  40  and secondary power circuit  60  may be eliminated where only one power stage is considered with respect to differentiating properties of primary verses secondary, and input verses output circuits, such as for systems where mains power is not used, or where power flow may be bidirectional, respectively; all these permeations of divisions between primary power circuit  40  and secondary power circuit  60  being possible to embody the full power converter circuit  1 , so that no limitation to the applicability of the invention is intended or implied by the choice of a using one primary power circuit  40  as input circuit, and one secondary power circuit  60  as output circuit to embody the full power converter circuit  1 . 
         [0080]    The embodiment of the present invention shown in  FIG. 1  includes electrically conductive cables  13 , and  14 . Electrically conductive cable  13  has terminals  13   a,    13   b.  Electrically conductive cable  14  has terminals  14   a,    14   b.  Electrically conductive cable&#39;s  13  terminal  13   a  connects to power converter circuit&#39;s  1  positive differential output terminal  1   d.  Electrically conductive cable&#39;s  14  terminal  14   a  connects to power converter circuit&#39;s  1  negative differential output terminal  1   e.    
         [0081]    The embodiment of the present invention shown in  FIG. 1  includes the application of a means of power consumption, herein also referred to as output load  90 , which is connected to electrically conductive cables  13 , and  14 . Output load  90  has means of functional connectivity to positive differential across-variable means of power consumption, herein also referred to as positive differential load terminal  90   a,  and means of functional connectivity to negative differential across-variable means of power consumption, herein also referred to as negative differential load terminal  90   b.  Output load&#39;s  90  positive differential load terminal  90   a  is connected to electrically conductive cable&#39;s  13  terminal  13   b;  output load&#39;s  90  negative differential load terminal  90   b  is connected to electrically conductive cable&#39;s  14  terminal  14   b.    
         [0082]    It should be understood that the preferred embodiment includes electrically conductive cables  13 ,  14  connected to power converter circuit&#39;s  1  positive differential output terminal  1   d,  and power converter circuit&#39;s  1  negative differential output terminal  1   e,  respectively, said electrically conductive cables  13 ,  14  being used to connect power converter circuit&#39;s  1  positive differential output terminal  1   d,  and power converter circuit&#39;s  1  negative differential output terminal  1   e  to output load&#39;s  90  positive differential load terminal  90   a,  and negative differential load terminal  90   b,  respectively, yet another embodiment may not require use of electrically conductive cables  13 ,  14 , instead directly connecting power converter circuit&#39;s  1  positive differential output terminal  1   d,  and power converter circuit&#39;s  1  negative differential output terminal  1   e  to output load&#39;s  90  positive differential load terminal  90   a,  and negative differential load terminal  90   b,  respectively; so that no limitation to the applicability of the invention is intended or implied by the choice of using electrically conductive cables  13 ,  14  connected to power converter circuit&#39;s  1  positive differential output terminal  1   d,  and power converter circuit&#39;s  1  negative differential output terminal  1   e,  respectively, instead of direct connection between output load&#39;s  90  positive differential load terminal  90   a,  and negative differential load terminal  90   b  with power converter circuit&#39;s  1  positive differential output terminal  1   d,  and power converter circuit&#39;s  1  negative differential output terminal  1   e,  respectively. 
         [0083]    It should be further understood that the preferred embodiment identifies the load as output load  90  which it indicates to be separate from power converter circuit  1 ; and that another embodiment may instead include the output load  90  within power converter circuit  1 , where power converter circuit&#39;s  1  positive differential output terminal  1   d,  and power converter circuit&#39;s  1  negative differential output terminal  1   e  would not be necessary, so that no limitation to the applicability of the invention is intended or implied by the choice of identifying the load as being separate from power converter circuit  1 . 
         [0084]    It should be yet further understood that the preferred embodiment identifies the load as output load  90  which has a preferred polarity, and that another embodiment may instead include a load which does not have a preferred polarity, so that no limitation to the applicability of the invention is intended or implied by the choice of output load  90  having a preferred polarity, where said polarity is with respect to the across-variable, herein also referred to as being with respect to voltage. 
         [0085]      FIG. 2 , which is a continuation of  FIG. 1 , shows additional details which relate to the power converter circuit&#39;s plant function, as it is referred to in system engineering terminology, for implementing the preferred embodiment. 
         [0086]    The embodiment of the present invention shown in  FIG. 2  includes a means of through-variable rectification, herein also referred to as primary rectifier  41 , connected within the primary power circuit  40 . The primary rectifier  41  has primary AC input terminals  41   a,    41   b,  positive differential output terminal  41   c,  and negative differential output terminal  41   d.  Primary rectifier  41  has its AC input  41   a  connected to primary power circuit&#39;s  40  line input terminal  40   a,  and its AC input  41   b  connected to a primary power circuit&#39;s  40  neutral terminal  40   b.    
         [0087]    Full bridge rectifier  41  accepts AC voltage and AC current on its primary AC input terminals  41   a,    41   b,  and allows conduction such that currents flow in a positive direction from its positive differential output terminal  41   c,  and currents flow in a positive direction into its negative differential output terminal  41   c.    
         [0088]    The embodiment of the present invention shown in  FIG. 2  includes a means of energy storage, said energy storage proportional to the time-integral through-variable storage, said means of energy storage herein also referred to as primary bulk capacitor  42 , connected within the primary power circuit  40 . The primary bulk capacitor  42  has positive differential terminal  42   a,  and negative differential terminal  42   b.  The primary bulk capacitor  42  has its positive differential terminal  42   a  connected to primary rectifier&#39;s  41  positive differential output terminal  41   c,  its negative differential terminal  42   b  connected to the full bridge rectifier&#39;s  41  negative differential output terminal  41   d.    
         [0089]    Primary bulk capacitor  42  stores energy including that received from mains power supply distribution  20  through primary power circuit  40  line input terminal  40   a,  neutral input terminal  40   b,  by way of primary rectifier  41  positive differential output terminal  41   c,  and negative differential output terminal  41   d.  In storing energy primary bulk capacitor  42  produces an across-variable, herein also referred to as a voltage, on its positive differential terminal  42   a  which is positive with respect to its negative differential terminal  42   b.  Voltage on primary bulk capacitor  42  is nearly DC due to primary rectifier  41  reestablishing it twice per line cycle at a level near the peak value of the voltage magnitude on mains power supply distribution  20  line terminal  20   a  with respect to neutral terminal  20   b.    
         [0090]    The embodiment of the present invention shown in  FIG. 2  includes a means effectively of DC-to-AC power conversion, herein also referred to as a DC-to-AC power converter circuit, comprising two means of through-variable switching, herein also referred to as two switching devices, and incorporating the functions of two means of anti-parallel through-variable rectification, herein also referred to as two anti-parallel diodes; said two switching devices herein also referred to as MOSFET switching device one  43 , and MOSFET switching device two  45 ; said two anti-parallel diodes herein also referred to as anti-parallel diode one  44 , and anti-parallel diode two  46 . MOSFET switching device one  43  is connected within the primary power circuit  40 . MOSFET switching device one  43  has drain terminal  43   a,  and source terminal  43   c.  MOSFET switching device one  43  has its drain terminal  43   a  connected to primary bulk capacitor&#39;s  42  positive differential terminal  42   a,  and primary rectifier&#39;s  41  positive differential output terminal  41   c.  Anti-parallel diode one  44  is connected within the primary power circuit  40 . Anti-parallel diode one  44  has cathode terminal  44   a,  and anode terminal  44   b.  Anti-parallel diode one  44  has its cathode terminal  44   a  connected to MOSFET switching device one&#39;s  43  drain terminal  43   a,  primary bulk capacitor&#39;s  42  positive differential terminal  42   a,  and primary rectifier&#39;s  41  positive differential output terminal  41   c.  Anti-parallel diode one  44  has its anode terminal  44   b  connected to MOSFET switching device one&#39;s  43  source terminal  43   c.  MOSFET switching device two  45  is connected within the primary power circuit  40 . MOSFET switching device two  45  has drain terminal  45   a,  and source terminal  45   c.  MOSFET switching device two  45  has its drain terminal  45   a  connected to MOSFET switching device one&#39;s  43  source terminal  43   c,  and anti-parallel diode one&#39;s  44  anode terminal  44   b.  MOSFET switching device two  45  has its source terminal  45   c  connected to primary bulk capacitor&#39;s  42  negative differential terminal  42   b,  and primary rectifier&#39;s  41  negative differential output terminal  41   d.  Anti-parallel diode two  46  is connected within the primary power circuit  40 . Anti-parallel diode two  46  has cathode terminal  46   a,  and anode terminal  46   b.  Anti-parallel diode two  46  has its cathode terminal  46   a  connected to MOSFET switching device two&#39;s  45  drain terminal  45   a,  MOSFET switching device one&#39;s  43  source terminal  43   c,  and anti-parallel diode one&#39;s  44  anode terminal  44   b.  Anti-parallel diode two  46  has its anode terminal  46   b  connected to MOSFET switching device two&#39;s  45  source terminal  45   c,  primary bulk capacitor&#39;s  42  negative differential terminal  42   b,  and primary rectifier&#39;s  41  negative differential output terminal  41   d.    
         [0091]    MOSFET switching device one  43  and MOSFET switching device two  45  each cycle their switching operations periodically, so that each persists in its on-state for almost half the cycle period, with the balance of the cycle spent in the off-state. MOSFET switching device one  43  and MOSFET switching device two  45  operate 180 degrees out of phase from each other, so that only one is in an on-state at any given time. By this operation, and through connection of MOSFET switching device one&#39;s  43  drain terminal  43   a  to primary bulk capacitor&#39;s  42  positive differential terminal  42   a,  and connection of MOSFET switching device two&#39;s  45  source terminal  45   c  to primary bulk capacitor&#39;s  42  negative differential terminal  42   b,  a differential voltage on MOSFET switching device two&#39;s  45  drain terminal  45   a  with respect to source terminal  45   c  persists for almost 50% of each cycle period, alternating with nearly no differential voltage being present for the balance of the cycle period, on MOSFET switching device one&#39;s  43  source terminal  43   c  and MOSFET switching device two&#39;s  45  drain terminal  45   a.  For the sake of simplicity of this illustration, forward voltage drops during conduction is considered to be zero across anti-parallel diode one&#39;s  44  anode terminal  44   b  with respect to its cathode terminal  44   a,  across anti-parallel diode two&#39;s  46  anode terminal  46   b  with respect to its cathode terminal  46   a,  across MOSFET switching device one&#39;s  43  drain terminal  43   a  with respect to its source terminal  43   c,  and across MOSFET switching device two&#39;s  45  drain terminal  45   a  with respect to its source terminal  45   c.    
         [0092]    It should be understood that other embodiments of this invention may employ switching devices from among several technologies, including BJT, MOSFET, IGBT, SiC JFET, and others, and that the preferred implementation which uses MOSFET technology devices for MOSFET switching device one  43  and MOSFET switching device two  45  may be constructed to use another technology switching device, so that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of MOSFET switching device one  43  and MOSFET switching device two  45  in the preferred embodiment. It should be further understood that other embodiments of this invention may omit anti-parallel diode one  44  and anti-parallel diode two  46 , where it may be preferred in those embodiments to use a parasitic anti-parallel diode in each switching device, for those technology switching devices having suitable parasitic anti-parallel diodes, so that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to use of anti-parallel diode one  44  and anti-parallel diode two  46  devices in the preferred embodiment. 
         [0093]    The embodiment of the present invention shown in  FIG. 2  includes a means of primary source energy-field coupling, said means of primary source energy-field coupling herein also referred to as primary series inductance  47 , said primary series inductance  47  being functionally connected within the primary power circuit  40 . Primary series inductance  47  has terminals  47   a,    47   b.  Primary series inductance  47  has its terminal  47   a  connected to anti-parallel diode two&#39;s  46  cathode terminal  46   a,  MOSFET switching device two&#39;s  45  drain terminal  45   a,  anti-parallel diode one&#39;s  44  anode terminal  44   b,  and MOSFET switching device one&#39;s  43  source terminal  43   c.    
         [0094]    The embodiment of the present invention shown in  FIG. 2  includes a primary series capacitor  48  connected within the primary power circuit  40 . Primary series capacitor  48  has terminals  48   a,    48   b.  Primary series capacitor  48  has its terminal  48   a  connected to primary series inductance&#39;s  47  terminal  47   b.    
         [0095]    The embodiment of the present invention shown in  FIG. 2  includes a shunt inductor  49  connected within the primary power circuit  40 . Shunt inductor  49  has terminals  49   a,    49   b.  Shunt inductor  49  has its terminal  49   a  connected to primary series capacitor&#39;s  48  terminal  48   b.  Shunt inductor  49  has its terminal  49   b  connected to anti-parallel diode two&#39;s  46  anode terminal  46   b,  MOSFET switching device two&#39;s  45  source terminal  45   c,  primary bulk capacitor&#39;s  42  negative terminal  42   b,  and primary rectifier&#39;s  41  negative differential output terminal  41   d.    
         [0096]    The embodiment of the present invention shown in  FIG. 2  includes a means of AC power energy-field coupling, herein also referred to as power transformer  50  connected within primary power circuit  40 . Power transformer  50  has insulation system comprising double insulation which is sufficient to provide safety protection against risk of electric shock, due to hazardous voltage on its primary, to an operator who comes into contact with bare conductors on its secondary. Power transformer  50  has means of functional connectivity to Means of AC coupler energy-field primary coupling, herein also referred to as primary terminals  50   a,    50   b,  and means of functional connectivity to Means of AC coupler energy-field secondary coupling, herein also referred to as secondary terminals  50   c,    50   d.  Power transformer  50  has its primary terminal  50   a  connected to shunt inductor&#39;s  49  terminal  49   a,  and primary series capacitor&#39;s  48  terminal  48   b.  Power transformer  50  has its primary terminal  50   b  connected to shunt inductor&#39;s  49  terminal  49   b,  anti-parallel diode two&#39;s  46  anode terminal  46   b,  MOSFET switching device two&#39;s  45  source terminal  45   c,  primary bulk capacitor&#39;s  42  negative terminal  42   b,  and primary rectifier&#39;s  41  negative differential output terminal  41   d.  Power transformer  50  has its secondary terminal  50   c  connected to primary power circuit&#39;s  40  output terminal output terminal  40   d.  Power transformer  50  has its secondary terminal  50   d  connected to primary power circuit&#39;s  40  output terminal output terminal  40   e.    
         [0097]    It should be understood that the preferred embodiment employs power transformer  50  with insulation construction providing safety protection against electrical shock due to hazardous voltages on its primary, in the event an operator makes physical contact with bare conductive elements of its secondary, said insulation construction classified as double insulation, which satisfies one criterion for SELV classification of the secondary circuit to which its secondary terminals are connected, and that other embodiments may employ power transformer  50  with greater or lesser levels of insulation, or none at all except for functional insulation, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of power transformer&#39;s  50  insulation construction and characteristics. 
         [0098]    Power transformer  50  receives power supplied to its primary terminals  50   a,    50   b  by a voltage-compliant current source comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49 . Power transformer  50  transforms power received on its primary terminals  50   a,    50   b  into power which it delivers to a load connected to its secondary terminals  50   c,    50   d.  Power transformer  50  delivers power to its secondary terminals  50   c,    50   d,  which are connected through primary power circuit&#39;s  40  output terminals  40   d,    40   e,  respectively, to current-compliant input impedance of the secondary power circuit&#39;s  60  power input terminals  60   a,    60   b,  respectively. 
         [0099]    Power transformer&#39;s  50  primary terminal  50   a  receives into it the sum of positive currents sourcing from shunt inductor&#39;s  49  terminal  49   a,  and primary series capacitor&#39;s  48  terminal  48   b,  such that transformer&#39;s  50  primary terminal  50   a  is caused to have a differential voltage that is positive with respect to its voltage on primary terminal  50   b,  in an amount as determined by reflection of power transformer&#39;s  50  secondary differential voltage on its secondary terminal  50   c  with respect to its secondary terminal  50   d,  to its primary terminals  50   a,    50   b.  Also, the sum of positive currents sourcing into shunt inductor&#39;s  49  terminal  49   a,  and primary series capacitor&#39;s  49  terminal  49   b,  conducts out of power transformer&#39;s  50  primary terminal  50   a,  such that primary terminal  50   a  is caused to have a differential voltage that is negative with respect to its voltage on primary terminal  50   b,  in an amount as determined by reflection of power transformer&#39;s  50  secondary differential voltage on its secondary terminal  50   c  with respect to its secondary terminal  50   d.  If direction of positive current out of shunt inductor&#39;s  49  terminal  49   a  and out of primary series capacitor&#39;s  48  terminal  48   b  differ as to polarity, then any resulting net positive current out of out of shunt inductor&#39;s  49  terminal  49   a  and out of primary series capacitor&#39;s  48  terminal  48   b  will conduct as positive current into power transformer&#39;s  50  primary terminal  50   a,  and that terminal is caused to have a differential voltage that is positive with respect to its voltage on primary terminal  50   b,  in an amount determined by reflection of power transformer&#39;s  50  differential voltage on its secondary terminal  50   c  with respect to its secondary terminal  50   d,  so that power is transferred into the power transformer&#39;s  50  primary terminals  50   a,    50   b;  or, a resulting net positive current into shunt inductor&#39;s  49  terminal  49   a  and into primary series capacitor&#39;s  48  terminal  48   b  will conduct as positive current out of power transformer&#39;s  50  primary terminal  50   a,  and that terminal is caused to have a differential voltage that is negative with respect to its voltage on primary terminal  50   b,  in an amount determined by reflection of power transformer&#39;s  50  secondary differential voltage on its secondary terminals  50   c  with respect to voltage on its secondary terminal  50   d,  so that power is transferred into the power transformer&#39;s  50  primary terminals  50   a,    50   b.    
         [0100]    The resonant circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49  has a maximum magnitude differential voltage limit of voltage-compliance it can supply across shunt inductor&#39;s  49  terminals  49   a,    49   b,  as a function of the characteristics of resonant circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49 , the working frequency of switching by MOSFET switching device one  43  and MOSFET switching device two  45 , the differential voltage of primary bulk capacitor&#39;s  42  positive differential terminal  42   a  with respect to negative differential terminal  42   b,  and the loading due to power transformer&#39;s  50  primary terminals  50   a,    50   b.  Power transformation performed by power transformer  50  establishes the maximum limit of voltage-compliance of differential voltage across its secondary terminals  50   c,    50   d  by a fixed ratio to the maximum limit voltage-compliance of differential voltage across its primary terminals  50   a,    50   b  due to the maximum limit of voltage-compliance of differential voltage across shunt inductor&#39;s  49  terminals  49   a,    49   b,  and the turns ratio of number of secondary winding turns to number of primary winding turns of power transformer  50 . 
         [0101]    Power transformer&#39;s  50  secondary terminals  50   c,    50   d  source current to the secondary power circuit  60  which is reflected net current of that conducting through power transformer&#39;s  50  primary terminals  50   a,    50   b  sourced from within the primary power circuit  40 ; and power transformer  50  has differential voltage on its secondary terminal  50   c,  with respect to that on its secondary terminal  50   d,  so that polarity is in a direction consistent with current direction through secondary terminal  50   c  so that as a result only positive power is sourced. 
         [0102]    It should be understood that the preferred embodiment for the purpose of illustrative simplicity employs a power transformer  50  that for all practical purposes of the preferred embodiment is treated as being ideal; and that magnetizing inductance associated with another embodiment of power transformer  50  shall be considered to have its effect included in that of shunt inductor  49  of the preferred embodiment, so that the combined effects of magnetizing inductance and shunt inductor  49  can be considered as being represented through the effect of shunt inductor  49  acting alone, but with an analytically reduced in situ inductance value than the discrete shunt inductor  49  possesses; and that means of leakage energy-field coupling of AC coupler energy-field primary coupling and means of leakage energy-field coupling of AC coupler energy-field secondary coupling, herein also referred to cumulatively as leakage inductance, associated with another embodiment of power transformer  50 , shall be considered to have its effect included in that of primary series inductance  47  of the preferred embodiment, so that the combined effects of leakage inductance and primary series inductance  47  can be considered as being represented by primary series inductance  49  alone, but with an analytically increased in situ inductance value than discrete primary series inductance  49  possesses. In an embodiment of power transformer  50  which is one variant of the preferred embodiment, magnetizing inductance could be designed to eliminate and replace shunt inductor  49 ; and effective leakage inductance as seen through power transformer&#39;s  50  primary terminals  50   a,    50   b  could be designed so that means of leakage energy-field coupling of AC coupler energy-field secondary coupling, herein also referred to as leakage inductance of secondary winding of power transformer&#39;s  50 , seen across secondary terminals  50   c,    50   d,  analytically reflected to power transformer&#39;s  50  primary terminals  50   a,    50   b,  together with means of leakage energy-field coupling of AC coupler energy-field primary coupling, herein also referred to as leakage inductance of primary winding of power transformer&#39;s  50 , see across primary terminals  50   a,    50   b,  eliminate and replace discrete primary series inductance  47 , and terminals connecting to primary series inductance&#39;s  47  terminal  47   a  in the preferred embodiment would instead connect directly with terminals connecting to primary series inductance&#39;s  47  terminal  47   b  in the variant embodiment. In practice, if the variant embodiment as described is not wholly achieved through design, then what values of magnetizing and leakage inductances which are achieved are supplemented with additional discrete elements of primary series inductance  47 , and shunt inductor  49 . No limitation of applicability of this description is intended or implied due to the simplifying assumption power transformer  50  is ideal in the preferred embodiment. 
         [0103]    It should be further understood that the preferred embodiment employs a power transformer  50  which has a single primary winding and a single secondary winding, and another embodiment may choose instead to employ a power transformer  50  which has either multiple primary windings, or multiple secondary windings, or both, and that no limitation of applicability of this description is intended or implied due to the simplifying assumption power transformer  50  having a single primary winding and a single secondary winding in the preferred embodiment. 
         [0104]    Anti-parallel diode one  44  allows energy to return to primary bulk capacitor  42  from the resonant circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49 , by conducting current to primary bulk capacitor&#39;s  42  positive differential terminal  42   a.  Anti-parallel diode one  44  may conduct current in a free-wheeling mode during limited conduction zones, which occur when both MOSFET switching device one  43  and MOSFET switching device two  45  are simultaneously in off-states, allowing forward voltage bias to exist across anti-parallel diode one  44  so that anti-parallel diode one  44  anode terminal  44   b  is positive with respect to cathode terminal  44   a,  when current flow requires this conductive path to satisfy the continuous flow characteristic of the current sourcing behavior of resonant circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49 . Anti-parallel diode two  46  will operate in a free-wheeling mode during limited conduction zones, which occur when both MOSFET switching device one  43  and MOSFET switching device two  45  are simultaneously in off-states, allowing forward voltage bias to exist across anti-parallel diode two  46  so that anti-parallel diode two  46  anode terminal  46   b  is positive with respect to cathode terminal  46   a,  when current flow requires this conductive path to satisfy the continuous flow characteristic of the current sourcing behavior of resonant circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49 . 
         [0105]    The free-wheeling behaviors of anti-parallel diode one  44  and anti-parallel diode two  46  due to current sourcing behavior of the circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49  allows for sequencing the switching from off-state to on-state of MOSFET switching device one  43  and MOSFET switching device two  45  to occur when there is nearly zero differential voltage across MOSFET switching device one&#39;s  43  drain terminal  43   a  with respect to its source terminal  43   c,  and across MOSFET switching device two&#39;s  45  drain terminal  45   a  with respect to its source terminal  45   c.  This sequencing technique taking advantage of the efficient nature of resonant switching is referred to as zero-voltage switching, or ZVS, which eliminates to a major degree the power dissipation losses that would occur during switching due to otherwise resistively discharging the energy stored in parasitic capacitances of MOSFET switching device one  43  and MOSFET switching device two  45 . 
         [0106]    The embodiment of the present invention shown in  FIG. 2  includes a means of secondary full wave through-variable rectification, herein also referred to as secondary full wave current rectification elements  61 , functionally connected within the secondary power circuit  60 . The secondary full wave current rectification elements  61  has secondary AC input terminals  61   a,    61   b,  positive differential output terminal  61   c,  and negative differential output terminal  61   d.  Secondary full wave current rectification elements  61  has its AC input  61   a  connected to secondary power circuit&#39;s  60  input terminal  60   a,  and its AC input  61   b  connected to secondary power circuit&#39;s  60  input terminal  60   b.  Secondary full wave current rectification elements  61  has its negative differential output terminal  61   d  connected to secondary power circuit&#39;s  60  ground input terminal  60   c.    
         [0107]    Secondary full wave current rectification elements  61  receives on its AC input terminals  61   a,    61   b  input power from power transformer&#39;s  50  secondary terminals  50   c,    50   d  via connections through secondary power circuit&#39;s  60  input terminals  60   a,    60   b,  respectively, and secondary power circuit&#39;s  60  input terminals  60   a,    60   b  connections with primary power circuit&#39;s  40  output terminals  40   d,    40   e,  respectively. Secondary full wave current rectification elements  61  allows conduction such that all currents flow in a positive direction from its positive differential output terminal  61   c,  and all currents flow in a positive direction into its negative differential output terminal  61   c.    
         [0108]    Relevant to the new utility of this circuit, as recognized by the subject invention, secondary full wave current rectification elements  61  acts to limit the maximum magnitude of differential working voltages where they are greatest in secondary power circuit  60 , by clamping the maximum magnitude of differential voltage on power transformer&#39;s  50  secondary terminal  50   c  with respect to that on its secondary terminal  50   d  so that it is equal the voltage magnitude of differential voltage of the power converter circuit  1 &#39;s positive differential output terminal  1   d  with respect to negative differential output terminal  1   e,  plus the addition of forward voltage drops of the secondary full wave current rectification elements  61 , plus the addition of forward voltage drops due to current conducting through any secondary stray resistances or semiconductor(s) in series-connection in the series circuit which includes power transformer&#39;s  50  secondary terminals  50   c  and  50   d,  secondary full wave current rectification elements  61 , and the series-connection of parallel circuit comprising secondary capacitor  62 , power converter circuit  1 &#39;s positive differential output terminal  1   d  and negative differential output terminal  1   e,  and output load  90  including electrically conductive cables  13  and  14 . 
         [0109]    It should be understood that the preferred embodiment employs diodes in the arrangement of a full bridge in secondary full wave current rectification elements  61  for the purpose of secondary rectification, and that other embodiments my choose alternative arrangements for this purpose of full wave rectifying a bipolar current into unipolar current, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of diodes in the arrangement of a full bridge in secondary full wave current rectification elements  61 . 
         [0110]    It should be further understood that in the preferred embodiment secondary full wave current rectification elements  61  has its negative differential output terminal  61   d  connected to secondary power circuit&#39;s  60  ground input terminal  60   c,  thereby establishing a reference voltage at ground potential against which differential circuit voltages may also be determined in terms of their absolute voltages, and that in other embodiments the reference voltage may be chosen to be other than ground, or there may be no reference voltage chosen within the secondary power circuit  60  or the power converter circuit  1 , and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of ground as a reference voltage within secondary power circuit  60 . 
         [0111]    It should be yet further understood that the preferred embodiment employs diodes in secondary full wave current rectification elements  61  for the purpose of secondary rectification, and that in other embodiments there are enhancements and alternatives for this purpose, such as synchronous rectification which may employ a MOSFET connected anti-parallel with each diode, or a MOSFET alone in place of each diode and which may or may not utilize each MOSFET&#39;s intrinsic diode, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of diodes as rectifiers in secondary full wave current rectification elements  61 . 
         [0112]    The embodiment of the present invention shown in  FIG. 2  includes a means of secondary energy storage, herein also referred to as a secondary capacitor  62  connected within the secondary power circuit  60 . The secondary capacitor  62  has positive differential terminal  62   a,  and negative differential terminal  62   b.  Secondary capacitor  62  has its positive differential terminal  62   a  connected to secondary full wave current rectification elements&#39;  61  positive differential output terminal  61   c.  Secondary capacitor  62  has its negative differential terminal  62   b  connected to secondary power circuit&#39;s  60  ground input terminal  60   c,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  and secondary power circuit&#39;s  60  negative differential output terminal  60   i.    
         [0113]    Secondary capacitor  62  stores energy including that received from secondary power circuit&#39;s  60  input terminals  60   a,    60   b,  delivered through secondary full wave current rectification elements&#39;  61  positive differential output terminal  61   c  and negative differential output terminal  61   d.  In storing energy, secondary capacitor  62  produces a differential voltage on its positive differential terminal  62   a  which is positive with respect to its negative differential terminal  62   b.  Differential voltage on secondary capacitor  62  is nearly DC due to primary rectifier  61  reestablishing it twice per working cycle at a level near the peak value of the voltage magnitude on secondary power circuit&#39;s  60  power input terminal  60   a  respect to secondary power circuit&#39;s  60  power input terminal  60   b.    
         [0114]    Secondary capacitor  62  has impedance which is current-compliant and this helps serve the requirement that the input impedance of secondary power circuit  60  is current-compliant. In the absence of secondary capacitor  62  the input impedance of the secondary power circuit  60  would be more dependent on that of other elements connected in the secondary power circuit  60 . Secondary capacitor  62  also provides storage of energy in the secondary power circuit which may source power as a current-compliant voltage source. 
         [0115]    Certain processes served in other embodiments by a secondary power circuit may require instead having output load power in the form of a voltage-compliant current source, such as for an electric arc metal welding process or a battery charger, and those other embodiments may eliminate secondary capacitor  62  as a source of significant capacitance in the secondary power circuit  60 , or may replace it instead with a voltage clamp or other means as may be necessary to limit maximum magnitude of voltage-compliance. It should be understood that the preferred embodiment produces output power in the form of a current-compliant voltage source, yet another embodiment can produce on its output instead a voltage-compliant current source where the maximum voltage-compliance level may be limited by design, so that no limitation to the applicability of the invention is intended or implied by the choice of a secondary power circuit output which is a current-compliant voltage source in the preferred embodiment. It should be further understood that the preferred embodiment employs secondary capacitor  62 , and that other embodiments may omit use of a secondary capacitor, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to use of secondary capacitor  62 . 
         [0116]    The embodiment of the present invention shown in  FIG. 2  includes an electrically conductive cable  63  connected within the secondary power circuit  60 . The electrically conductive cable  63  has terminals  63   a,    63   b.  The electrically conductive cable  63  has its terminal  63   a  connected to secondary full wave current rectification elements&#39;  61  positive differential output terminal  61   c,  and secondary capacitor&#39;s  62  positive differential terminal  62   a.  The electrically conductive cable  63  has its terminal  63   b  connected to secondary power circuit&#39;s  60  positive differential output terminal  60   h.    
         [0117]    Electrically conductive cable  63  provides a means to route the path of current to secondary power circuit&#39;s  60  positive differential output terminal  60   h,  so that it may conduct through a device&#39;s aperture capable of measuring the total net current intercepted through the plane of the aperture, said device and aperture to be herein introduced and described in the section describing  FIG. 3 . 
         [0118]    It should be understood that the preferred embodiment employs a electrically conductive cable  63  intended for use to facilitate inclusion of another device into the circuit, and that other embodiments may not require this provision, so that another embodiment may eliminate electrically conductive cable  63 , replacing it instead with a point of contact superimposing points connecting in the preferred embodiment with electrically conductive cable&#39;s  63  terminal  63   a  onto those connecting with terminal  63   a,  and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of employing electrically conductive cable  63  for the purpose of facilitating inclusion of another device into the circuit. 
         [0119]    Relevant to the new utility of this circuit recognized by the subject invention, secondary full wave current rectification elements  61  acts to limit the maximum magnitude of differential working voltages where they are greatest in secondary power circuit  60 , by clamping the maximum magnitude of differential voltage on power transformer&#39;s  50  secondary terminal  50   c  with respect to that on its secondary terminal  50   d  so that it is equal the voltage magnitude of differential voltage of the power converter circuit  1 &#39;s positive differential output terminal  1   d  with respect to negative differential output terminal  1   e,  plus the addition of forward voltage drops of the secondary full wave current rectification elements  61 , plus the addition of forward voltage drops due to current conducting through any secondary stray resistances or semiconductor(s) in series-connection in the series circuit which includes power transformer&#39;s  50  secondary terminals  50   c  and  50   d,  secondary full wave current rectification elements  61 , and the parallel connection of secondary capacitor  62 , electrically conductive cable  63 , power converter circuit  1 &#39;s positive differential output terminal  1   d  and negative differential output terminal  1   e,  electrically conductive cables  13  and  14 , and output load  90 . 
         [0120]      FIG. 3 , which is a continuation of  FIG. 2 , shows additional details which relate to the power converter circuit&#39;s  1  actuator, control, sense and feedback functions, as they are referred to in system engineering terminology, for implementing the preferred embodiment. 
         [0121]    In addition to terminals and connections described in  FIG. 1 , primary power circuit  40  also has in-phase driver one terminal  40   f,  reverse-phase driver one terminal  40   g,  in-phase driver two terminal  40   h,  and reverse-phase driver two terminal  40   i.    
         [0122]    In addition to terminals and connections described in  FIG. 1  and  FIG. 2 , secondary power circuit  60  also has actuator one in-phase terminal  60   d,  actuator one reverse-phase terminal  60   e,  actuator two in-phase terminal  60   f,  and actuator two reverse-phase terminal  60   g.    
         [0123]    Secondary power circuit&#39;s  60  actuator one in-phase terminal  60   d  is connected to primary power circuit&#39;s  40  in-phase driver one terminal  40   f.  Secondary power circuit&#39;s  60  actuator one reverse-phase terminal  60   e  is connected to primary power circuit&#39;s  40  reverse-phase driver one terminal  40   g.  Secondary power circuit&#39;s  60  actuator two in-phase terminal  60   f  is connected to primary power circuit&#39;s  40  in-phase driver two terminal  40   h.  Secondary power circuit&#39;s  60  actuator two reverse-phase terminal  60   g  is connected to primary power circuit&#39;s  40  reverse-phase driver two terminal  40   i.    
         [0124]    Some connections between secondary power circuit  60  and primary power circuit  40  are for the purpose of secondary power circuit  60  actuating the power conversion process in primary power circuit  40 . Secondary power circuit&#39;s  60  terminals being used for this purpose are actuator one in-phase terminal  60   d,  actuator one reverse-phase terminal  60   e,  actuator two in-phase terminal  60   f,  and actuator two reverse-phase terminal  60   g.  Primary power circuit&#39;s  40  terminals being used for this purpose are in-phase driver one terminal  40   f,  reverse-phase driver one terminal  40   g,  in-phase driver two terminal  40   h,  and reverse-phase driver two terminal  40   i.    
         [0125]    In addition to terminals and connections described in  FIG. 2 , MOSFET switching device one  43  also has gate terminal  43   b,  and MOSFET switching device two  45  also has gate terminal  45   b.    
         [0126]    The embodiment of the present invention shown in  FIG. 3  includes a driver circuit one  51  connected within the primary power circuit  40 . Driver circuit one  51  has in-phase output terminal  51   a,  reverse-phase output terminal  51   b,  reverse-phase input terminal  51   c,  and in-phase input terminal  51   d.  Driver circuit one  51  has its in-phase output terminal  51   a  connected to MOSFET switching device one&#39;s  43  gate terminal  43   b,  and its reverse-phase output terminal  51   b  connected to MOSFET switching device one&#39;s  43  source terminal  43   c,  anti-diode one&#39;s  44  terminal  44   b,  MOSFET switching device two&#39;s  45  drain terminal  45   a,  anti-diode two&#39;s  46  terminal  46   a,  and primary series inductance&#39;s  47  terminal  47   a.    
         [0127]    Driver circuit one  51  performs a function of conditioning and delivering power to MOSFET switching device one&#39;s  43  gate terminal  43   b  and source terminal  43   c,  necessary to drive and maintain MOSFET switching device one  43  in either an on-state or an off-state, or to cause transition from on-state to off-state, or from off-state to on-state. 
         [0128]    The embodiment of the present invention shown in  FIG. 3  includes a driver circuit two  52  connected within the primary power circuit  40 . Driver circuit two  52  has in-phase output terminal  52   a,  reverse-phase output terminal  52   b,  reverse-phase input terminal  52   c,  and in-phase input terminal  52   d.  Driver circuit two  52  has its in-phase output terminal  52   a  connected to MOSFET switching device two&#39;s  45  gate terminal  45   b,  and its reverse-phase output terminal  52   b  connected to MOSFET switching device two&#39;s  45  source terminal  45   c,  anti-parallel diode two&#39;s  46  terminal  46   b,  power transformer&#39;s  50  primary terminal  50   b,  shunt inductor&#39;s  49  terminal  49   b,  primary bulk capacitor&#39;s  42  negative differential terminal  42   b,  and primary rectifier&#39;s  41  negative differential output terminal  41   d.    
         [0129]    Driver circuit two  52  performs a function of conditioning and delivering power to MOSFET switching device two&#39;s  45  gate terminal  45   b  and source terminal  45   c,  necessary to drive and maintain MOSFET switching device two  45  in either an on-state or an off-state, or to cause transition from on-state to off-state, or from off-state to on-state. 
         [0130]    The embodiment of the present invention shown in  FIG. 3  includes a pulse transformer one  53  connected within the primary power circuit  40 . Pulse transformer one  53  has insulation system comprising double insulation which is sufficient to provide safety protection against risk of electric shock, due to hazardous voltage on its primary, to an operator who comes into contact with bare conductors on its secondary. Pulse transformer one  53  has reverse-phase primary output terminal  53   a,  in-phase primary output terminal  53   b,  in-phase secondary input terminal  53   c,  and reverse-phase secondary input terminal  53   d.  Pulse transformer one  53  has its reverse-phase primary output terminal  53   a  connected to driver circuit one&#39;s  51  reverse-phase input terminal  51   c,  and its in-phase primary output terminal  53   b  connected to driver circuit one&#39;s  51  in-phase input terminal  51   d.  Pulse transformer one  53  has its in-phase secondary input terminal  53   c  connected to primary power circuit&#39;s  40  in-phase driver one terminal  40   f,  and its reverse-phase secondary input terminal  53   d  connected to primary power circuit&#39;s  40  reverse-phase driver one terminal  40   g.    
         [0131]    Pulse transformer one  53  performs two functions simultaneously, which are essential for controlled command and actuation of the MOSFET switching device one  43  so that it switches between on-state and off-state upon command: first, transfer of drive power from secondary power circuit&#39;s  60  actuator one in-phase terminal  60   d,  and actuator one reverse-phase terminal  60   e,  to the driver circuit one&#39;s  51  in-phase input terminal  51   d,  and reverse-phase input terminal  51   c;  and second, communication of drive command signal from secondary power circuit&#39;s  60  actuator one in-phase terminal  60   d,  actuator one reverse-phase terminal  60   e,  to the driver circuit one&#39;s  51  in-phase input terminal  51   d,  and reverse-phase input terminal  51   c.    
         [0132]    Pulse transformer one  53  also provides a means for insulating elements of its secondary from elements of its primary, which is essential to providing protection to an operator against electric shock from hazardous voltages on the primary in the event of physical contact with bare conductive elements on the secondary. 
         [0133]    The embodiment of the present invention shown in  FIG. 3  includes a pulse transformer two  54  connected within the primary power circuit  40 . Pulse transformer two  54  has insulation system comprising double insulation which is sufficient to provide safety protection against risk of electric shock, due to hazardous voltage on its primary, to an operator who comes into contact with bare conductors on its secondary. Pulse transformer two  54  has reverse-phase primary output terminal  53   a,  in-phase primary output terminal  53   b,  in-phase secondary input terminal  53   c,  and reverse-phase secondary input terminal  53   d.  Pulse transformer two  54  has its in-phase secondary input terminal  54   c  connected to primary power circuit&#39;s  40  in-phase driver two terminal  40   h,  and its reverse-phase secondary input terminal  54   d  connected to primary power circuit&#39;s  40  reverse-phase driver two terminal  40   i.    
         [0134]    Pulse transformer two  54  performs two functions simultaneously, which are essential for controlled command and actuation of the MOSFET switching device two  45  so that it switches between on-state and off-state upon command: first, transfer of drive power from secondary power circuit&#39;s  60  actuator one in-phase terminal  60   f,  and actuator one reverse-phase terminal  60   g  terminals, to the driver circuit two&#39;s  52  in-phase input terminal  52   d,  and reverse-phase input terminal  52   c;  and second, communication of drive command signal from secondary power circuit&#39;s  60  actuator two in-phase terminal  60   f,  actuator two reverse-phase terminal  60   g,  to the driver circuit two&#39;s  52  in-phase input terminal  52   d,  and reverse-phase input terminal  52   c.    
         [0135]    Pulse transformer two  54  also provides a means for insulating elements of its secondary from elements of its primary, which is essential to providing protection to an operator against electric shock from hazardous voltages on the primary in the event of physical contact with bare conductive elements on the secondary. 
         [0136]    It should be understood that the preferred embodiment employs pulse transformer one  53  and pulse transformer two  54  with turns ratios such that they transform power from one set of current and voltage variables into another set which is essentially identical, but that another embodiment may use pulse transformer one  53  and pulse transformer two  54  with different turns ratio to transform power from one set of current and voltage variables into another set, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice to use pulse transformer one  53  and pulse transformer two  54  in the mode of transforming power in a ratio of one to one, where the differential voltage on transformer one&#39;s  53  reverse-phase primary output terminal  53   a  with respect to in-phase primary output terminal  53   b  is equal to the differential voltage on transformer one&#39;s  53  reverse-phase secondary input terminal  53   d  with respect to in-phase secondary input terminal  53   c,  and where the differential voltage on pulse transformer two&#39;s  54  reverse-phase primary output terminal  54   a  with respect to in-phase primary output terminal  54   b  is equal to the differential voltage on pulse transformer two&#39;s  54  reverse-phase secondary input terminal  54   d  with respect to in-phase secondary input terminal  54   c.    
         [0137]    It should be further understood that the preferred embodiment employs pulse transformer one  53  and pulse transformer two  54  with insulation construction providing safety protection against electrical shock due to hazardous voltages on their primaries, in the event an operator makes physical contact with bare conductive elements of their secondaries, with said insulation construction classified as double insulation which satisfies one criterion for SELV classification of the secondary circuit to which its secondary terminals are connected, and that other embodiments may employ pulse transformer one  53  and pulse transformer two  54  with greater or less satisfactory levels of safety protection insulations, or none at all except for functional insulations, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of pulse transformer one&#39;s  53  and pulse transformer two&#39;s  54  insulation construction and characteristics. 
         [0138]    It should be yet further understood that the preferred embodiment separately employs pulse transformer one  53  and pulse transformer two  54 , and that other embodiments in place of these may employ a single pulse that performs the functions of both pulse transformer one  53  and pulse transformer two  54 , as for instance where two isolated secondary windings may be employed on a single pulse transformer, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice to employ pulse transformer one  53  and pulse transformer two  54 . 
         [0139]    It should be yet further understood that the preferred embodiment employs pulse transformer one  53  and pulse transformer two  54 , and that other embodiments may employ different techniques to perform the functions served by pulse transformer one  53  and pulse transformer two  54 , as for instance where the source of power being derived in this embodiment through pulse transformer one  53  and pulse transformer two  54  may instead be derived from the primary circuits, or auxiliary primary circuits, or in the case of a primary connected control circuit, where the employed device or devices do not provide DC galvanic isolation; and the driver command signal being derived in this embodiment also through pulse transformer one  53  and pulse transformer two  54  may instead be derived through other means, such as through an opto-coupler, or in the case of a primary connected control circuit, where the employed device or devices do not provide DC galvanic isolation, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice to employ pulse transformer one  53  and pulse transformer two  54 . 
         [0140]    The embodiment of the present invention shown in  FIG. 3  includes actuator circuit one  64  connected within the secondary power circuit  60 . Actuator circuit one  64  has in-phase output terminal  64   a,  reverse-phase output terminal  64   b,  in-phase input terminal  64   c,  and reverse-phase input terminal  64   d.  Actuator circuit one  64  has its in-phase output terminal  64   a  connected to secondary power circuit&#39;s  60  actuator one in-phase terminal  60   d,  and its reverse-phase output terminal  64   b  connected to secondary power circuit&#39;s  60  actuator one reverse-phase terminal  60   e.    
         [0141]    The embodiment of the present invention shown in  FIG. 3  includes actuator circuit two  65  connected within the secondary power circuit  60 . Actuator circuit two  65  has in-phase output terminal  65   a,  reverse-phase output terminal  65   b,  in-phase input terminal  65   c,  and reverse-phase input terminal  65   d.  Actuator circuit two  65  has its in-phase output terminal  65   a  connected to secondary power circuit&#39;s  60  actuator two in-phase terminal  60   f,  and its reverse-phase output terminal  65   b  connected to secondary power circuit&#39;s  60  actuator two reverse-phase terminal  60   g.    
         [0142]    Actuator circuit one  64  acts as an interface to pulse transformer one  53 , and subsequently to driver circuit one  51 . Actuator circuit one  64  acts through secondary power circuit&#39;s  60  actuator one in-phase terminal  60   d  connected to primary power circuit&#39;s  40  in-phase driver one terminal  40   f,  and through secondary power circuit&#39;s  60  actuator one reverse-phase terminal  60   e  connected to primary power circuit&#39;s  40  reverse-phase driver one terminal  40   g,  as an interface to pulse transformer one  53 , and subsequently to driver circuit one  51 . 
         [0143]    Actuator circuit two  65  acts as an interface to pulse transformer two  54 , and subsequently to driver circuit two  52 . Actuator circuit two  65  acts through secondary power circuit&#39;s  60  actuator two in-phase terminal  60   f  connected to primary power circuit&#39;s  40  in-phase driver two terminal  40   h,  and through secondary power circuit&#39;s  60  actuator two reverse-phase terminal  60   g  connected to primary power circuit&#39;s  40  reverse-phase driver two terminal  40   i,  as an interface to pulse transformer two  54 , and subsequently to driver circuit two  52 . 
         [0144]    These interfaces, actuator circuit one  64  and actuator circuit two  65 , allow their low power input signals to be amplified into higher power output signals, with conditioning of current and voltage rise and fall times, suitable for delivering the instantaneous power and control required by driver circuit one  51  and driver circuit two  52 , respectively. 
         [0145]    The embodiment of the present invention shown in  FIG. 3  includes control circuit  66  connected within the secondary power circuit  60 . The control circuit  66  has actuator one in-phase output terminal  66   a,  actuator one reverse-phase output terminal  66   b,  actuator two in-phase output terminal  66   c,  actuator two reverse-phase output terminal  66   d,  ground terminal  66   e,  current monitor input signal terminal  66   g,  and secondary terminal voltage monitor input signal terminal  66   h.  The control circuit  66  has its actuator one in-phase output terminal  66   a  connected to actuator circuit one&#39;s  64  in-phase input terminal  64   c,  and its reverse-phase output terminal  66   b  connected to actuator circuit one&#39;s  64  reverse-phase input terminal  64   d.  The control circuit  66  has its actuator two in-phase output terminal  66   c  connected to actuator circuit two&#39;s  65  in-phase input terminal  65   c,  and its reverse-phase output terminal  66   d  connected to actuator circuit two&#39;s  65  reverse-phase input terminal  65   d.  The control circuit  66  has its ground terminal  66   e  connected to secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  and secondary power circuit&#39;s  60  input ground terminal  60   c.    
         [0146]    Control circuit  66  acts to coordinate the switching actions of MOSFET switching device one  43  and MOSFET switching device two  45 , by controlling actuator one  64  through control circuit&#39;s  66  actuator one in-phase output terminal  66   a,  actuator one reverse-phase output terminal  66   b,  and by controlling actuator two  65  through control circuit&#39;s  66  actuator two in-phase output terminal  66   c,  actuator two reverse-phase output terminal  66   d.    
         [0147]    Control circuit  66  regulates the working frequency of switching actions of MOSFET switching device one  43  and MOSFET switching device two  45 . Control circuit  66  performs this regulation to subsequently regulate the variables of voltage and current being reported through control circuit&#39;s  66  current monitor input signal terminal  66   g,  and secondary terminal voltage monitor input signal terminal  66   h,  both with respect to ground terminal  66   e.  The range of working frequencies is limited by control circuit  66  to correspond with a behavior of primary resonant circuit comprising primary series inductance  47 , primary series capacitor  48 , and shunt inductor  49 , and power transformer  50 , such that greater gain ratio of differential voltage across power transformer&#39;s  50  primary terminals  50   a,    50   b,  to differential voltage across primary bulk capacitor&#39;s  42  positive differential terminal  42   a,  negative differential terminal  42   b,  results from lower working frequency, and lower gain ratio results from higher working frequency. 
         [0148]    It should be understood that the preferred embodiment employs through control circuit  66  a means of regulation for output load variables of voltage or current, which are sourced by power converter circuit  1 , and that other embodiments may employ fewer or greater number, or types of regulated variables, or none at all such as for an open loop control, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of regulation and its particular variables of regulation. 
         [0149]    It should be further understood that the preferred embodiment connects control circuit  66  within the secondary power circuit  60 , and another embodiment may instead connect its control circuit within the primary power circuit  40 , or may incorporate lumped or distributed control circuits connected within primary and secondary circuits, along with the necessary subsequent changes to how sensed output variables have their monitor and fault signals passed through an isolation boundary from secondary power circuit  60  to the control circuit in primary power circuit  40 , and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of connecting control circuit  66  within the secondary power circuit  40 . 
         [0150]    The embodiment of the present invention shown in  FIG. 3  includes current sensor  67  connected within the secondary power circuit  60 . Current sensor  67  has in-phase output terminal  67   a,  reverse-phase output terminal  67   b,  and a current sensing aperture  67   c,  with a front face  67   d  through which passes electrically conductive cable  63 . Current sensor  67  incorporates a Hall Effect device to detect current conducting through its current sensing aperture  67   c  in a direction from its front face  67   d  through current sensor&#39;s  67  current sensing aperture  67   c.  Electrically conductive cable  63  is routed through current sensing aperture  67   c,  with conductive cable&#39;s  63  terminal  63   a  being extended from current sensor&#39;s  67  front face  67   d,  and conductive cable&#39;s  63  terminal  63   b  being passed through current sensor&#39;s  67  current sensing aperture  67   c,  beyond which it is connected into the circuit, so that conventional current conducted in the direction from current sensor&#39;s  67  front face  67   d  conducting through current sensing aperture  67   c  corresponds to direction of conventional current conducted from secondary capacitor&#39;s  62  positive differential terminal  62   a  and secondary full wave current rectification elements&#39;  61  positive differential output terminal  61   c  to the secondary power circuit&#39;s  60  positive differential output terminal  60   h.  Current sensor  67  has its in-phase output terminal  67   a  connected to control circuit&#39;s  66  current monitor input signal  66   g,  and its reverse-phase output terminal  67   b  connected to control circuit&#39;s  66  ground terminal  66   e,  secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  and secondary power circuit&#39;s  60  input ground terminal  60   c.    
         [0151]    Current sensor  67  senses the polarity and level of current passing through its current sensing aperture  67   c,  said current subsequently being conducted to power converter circuit&#39;s  1  positive differential output terminal  1   d  via secondary power circuit&#39;s  60  positive differential terminal  60   h.  Current sensor  67  then represents this measured current polarity and level through a signal it generates on in-phase output terminal  67   a  with respect to its reverse-phase output terminal  67   b,  this signal then being conducted to control circuit&#39;s  66  current monitor input signal  66   g  with respect to control circuit&#39;s  66  ground terminal  66   e.    
         [0152]    It should be understood that the preferred embodiment employs current sensor  67 , which is based upon its incorporation of a Hall Effect sensing device, and other embodiments may instead employ different techniques to measure and report current polarity and levels, or may choose to not measure polarity or current levels, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to the use of current sensor  67  and its particular current sensing technique. 
         [0153]    The embodiment of the present invention shown in  FIG. 3  includes voltage sensor  68  connected within the secondary power circuit  60 . Voltage sensor  68  has positive differential load terminal  68   a,  negative differential load terminal  68   b,  positive differential output terminal  68   c,  and negative differential output terminal  68   d.  Voltage sensor  68  has its positive differential load terminal  68   a  connected to secondary power circuit&#39;s  60  positive differential output terminal  60   h  and electrically conductive cable&#39;s  63  terminal  63   b.  Voltage sensor  68  has its negative differential load terminal  68   b  connected to secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  and secondary power circuit&#39;s  60  ground input terminal  60   c.  Voltage sensor  68  has its positive differential output terminal  68   c  connected to control circuit&#39;s  66  secondary terminal voltage monitor input signal terminal  66   h,  and its negative differential output terminal  68   d  connected to control circuit&#39;s  66  ground terminal  66   e,  secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  and secondary power circuit&#39;s  60  input ground terminal  60   c.    
         [0154]    Voltage sensor  68  senses the polarity and magnitude of differential voltage appearing on secondary power circuit&#39;s  60  positive differential output terminal  60   h  with respect to negative differential output terminal  60   i.  Voltage sensor  68  then represents this measured voltage level through a signal it generates on its positive differential output terminal  68   c  with respect to its negative differential output terminal  68   d,  this signal then being conducted to control circuit&#39;s  66  secondary terminal voltage monitor input signal terminal  66   h  with respect to control circuit&#39;s  66  ground terminal  66   e.    
         [0155]    It should be understood that the preferred embodiment employs voltage sensor  68  which senses and measures differential voltage appearing on secondary power circuit&#39;s  60  positive differential output terminal  60   h  with respect to negative differential output terminal  60   i,  and that other embodiments may instead measure voltage at a different point, or points, or may choose to not measure voltage levels, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to the use of voltage sensor  68  and the particular location at which it senses and measures voltage. 
         [0156]      FIG. 4 , which is a continuation of  FIG. 3 , shows additional details for implementing the preferred embodiment, which relate to the power converter circuit&#39;s fault detection and fault limit control functions, and which act to prevent loss of protection from electric shock due to a single fault. 
         [0157]    In addition to the terminals and connections of control circuit  66  described herein for  FIG. 3 , control circuit  66  also has fault input signal terminal  66   j  in the preferred embodiment of the present invention as shown in  FIG. 4 . 
         [0158]    The embodiment of the present invention shown in  FIG. 4  includes output over-voltage sensor  69  connected within the secondary power circuit  60 . Output over-voltage sensor  69  has positive differential load terminal  69   a,  negative differential load terminal  69   b,  positive differential output terminal  69   c,  and negative differential output terminal  69   d.  Output over-voltage sensor  69  has its positive differential load terminal  69   a  connected to secondary power circuit&#39;s  60  positive differential output terminal  60   h,  electrically conductive cable&#39;s  63  terminal  63   b,  and voltage sensor&#39;s  68  positive differential load terminal  68   a.  Output over-voltage sensor  69  has its negative differential load terminal  69   b  connected to its negative differential output terminal  69   d,  secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  secondary power circuit&#39;s  60  ground input terminal  60   c,  voltage sensor&#39;s  68  negative differential load terminal  68   b,  and control circuit&#39;s  66  ground terminal  66   e.    
         [0159]    The embodiment of the present invention shown in  FIG. 4  includes transformer over-voltage sensor  70  connected within the secondary power circuit  60 . Transformer over-voltage sensor  70  has input terminals  70   a,    70   b,  positive differential output terminal  70   c,  and negative differential output terminal  70   d.  Transformer over-voltage sensor  70  has its input terminal  70   a  connected to secondary power transformer&#39;s  50  secondary terminal  50   c,  and secondary full wave current rectification elements&#39;  61  AC input terminal  61   a.  Transformer over-voltage sensor  70  has its input terminal  70   b  connected to secondary power transformer&#39;s  50  secondary terminal  50   d,  and secondary full wave current rectification elements&#39;  61  AC input terminal  61   b.    
         [0160]    The embodiment of the present invention shown in  FIG. 4  includes fault limit circuit  71  connected within the secondary power circuit  60 . Fault limit circuit  71  has output over-voltage fault input terminal  71   a,  transformer over-voltage fault input terminal  71   b,  fault shutdown terminal  71   d,  and signal ground terminal  71   e.  Fault limit circuit  71  has its output over-voltage fault input terminal  71   a  connected to output over-voltage sensor&#39;s  69  positive differential output terminal  69   c.  Fault limit circuit  71  has its transformer over-voltage fault input terminal  71   b  connected to transformer over-voltage sensor&#39;s  70  positive differential output terminal  70   c.  Fault limit circuit  71  has its signal ground terminal  71   e  connected to output over-voltage sensor&#39;s  69  negative differential output terminal  69   d  and negative differential load terminal  69   b,  transformer over-voltage sensor&#39;s  70  negative differential output terminal  70   d,  control circuit&#39;s  66  ground terminal  66   e,  secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  and secondary power circuit&#39;s  60  input ground terminal  60   c.  Fault limit circuit  71  has its fault shutdown terminal  71   d  connected to control circuit&#39;s  66  fault input signal terminal  66   j.    
         [0161]    An output over-voltage type fault signal may be issued by output over-voltage sensor&#39;s  69  positive differential output terminal  69   c  with respect to its negative differential output terminal  69   d,  and received by fault limit circuit&#39;s  71  output over-voltage fault input terminal  71   a  with respect to fault limit circuit&#39;s  71  signal ground terminal  71   e;  or a transformer over-voltage type fault may be issued by transformer over-voltage sensor&#39;s  70  positive differential output terminal  70   c  with respect to its negative differential output terminal  70   d,  and received by transformer over-voltage fault input terminal  71   b  with respect to fault limit circuit&#39;s  71  signal ground terminal  71   e;  which for either or both of these events will result in fault limit circuit  71  issuing a fault signal on its fault shutdown terminal  71   d  with respect to its signal ground terminal  71   e.  A fault signal issued through fault limit circuit&#39;s  71  fault shutdown terminal  71   d  with respect to its signal ground terminal  71   e  will be conducted to control circuit&#39;s  66  fault input signal terminal  66   j  with respect to ground terminal  66   e,  and control circuit  66  will subsequently cause the switching actions of MOSFET switching device one  43  and MOSFET switching device two  45  to cease, and result in them being maintained at high impedances corresponding to their off-states. Resetting the latched off condition requires first removing, then restoring of AC mains supply power at power converter circuit&#39;s  1  line terminal  1   a.    
         [0162]    Output over-voltage sensor  69  senses the polarity and level of differential voltage appearing on secondary power circuit&#39;s  60  positive differential output terminal  60   h  with respect to negative differential output terminal  60   i.  Output over-voltage sensor  69  then compares this measured voltage polarity and level with a preset limit value, and determines that an output over-voltage type fault exists in the event the measured voltage magnitude exceeds the preset limit value. In the event an output over-voltage type fault exists, output over-voltage sensor  69  issues a signal which it generates on its positive differential output terminal  69   c  with respect to its negative differential output terminal  69   d,  this signal then being conducted to fault limit circuit&#39;s  71  output over-voltage fault input terminal  71   a  with respect to fault limit circuit&#39;s  71  signal ground terminal  71   e.    
         [0163]    It should be understood that the preferred embodiment employs output over-voltage sensor  69  which senses and measures differential voltage appearing on secondary power circuit&#39;s  60  positive differential output terminal  60   h  with respect to negative differential output terminal  60   i,  and that other embodiments may instead measure absolute or differential voltage at a different point, or points, or may choose to not measure voltage levels, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to the use of output over-voltage sensor  69  and the particular locations at which it senses and measures differential voltage. 
         [0164]    Transformer over-voltage sensor  70  senses the magnitude of differential voltage appearing on secondary power transformer&#39;s  50  secondary terminal  50   c  with respect to secondary power transformer&#39;s  50  secondary terminal  50   d.  Transformer over-voltage sensor  70  then compares this measured voltage magnitude&#39;s value with a preset limit value, and determines that a transformer over-voltage type fault exists in the event the measured voltage magnitude exceeds the preset limit value. In the event an transformer over-voltage type fault exists, transformer over-voltage sensor  70  issues a signal which it generates on its positive differential output terminal  70   c  with respect to its negative differential output terminal  70   d,  this signal then being conducted to fault limit circuit&#39;s  71  transformer over-voltage fault input terminal  71   b  with respect to fault limit circuit&#39;s  71  signal ground terminal  71   e.    
         [0165]    It should be understood that the preferred embodiment employs means of fault detection and fault limit control for differential voltage variables of secondary circuit output terminal voltage and transformer secondary voltage and that other embodiments may employ fewer or greater number or types of fault detection variables and subsequent fault limit controls, or none at all, and that no limit on the applicability of this embodiment is intended, implied, or should be inferred due to choice of fault limit control, particular differential voltage variables for detection, or particular modes of fault limit operation. 
         [0166]      FIG. 5  is a continuation of  FIG. 4 , and describes another embodiment through additional details relating to the power converter circuit&#39;s supplementary fault detection, supplementary fault limit control, and supplementary sense and feedback functions, which are generally employed in high precision power conversion systems to provide higher reliability and greater precision safeguard for a load, whether remote or local, against poor regulation or over-voltage stress, especially where voltage drops in electrically conductive cables  13 , and  14  may become significant errors with respect to the load&#39;s regulation and fault detection. It should be understood that the embodiment of  FIG. 1  through  FIG. 4 , and the embodiment of  FIG. 5  are each exemplary embodiments and that numerous other ways of implementing the present invention will become apparent after reviewing this description. 
         [0167]    In addition to terminals and connections described in  FIG. 1  through  FIG. 4 , power converter circuit  1  in  FIG. 5  also has positive differential load sense terminal  1   f,  and negative differential load sense terminal  1   g.    
         [0168]    In addition to terminals and connections described in  FIG. 1  through  FIG. 4 , secondary power circuit  60  in  FIG. 5  also has positive differential load sense terminal  60   j,  and negative differential load sense terminal  60   k.    
         [0169]    Secondary power circuit&#39;s  60  positive differential load sense terminal  60   j  is connected to power converter circuit&#39;s  1  positive differential load sense terminal  1   f,  and secondary power circuit&#39;s  60  negative differential load sense terminal  60   k  is connected to power converter circuit&#39;s  1  negative differential load sense terminal  1   g.    
         [0170]    The embodiment of the present invention shown in  FIG. 5  includes the application of electrically conductive cables  15 ,  16  connecting the power converter circuit  1  to the output load  90 . Electrically conductive cable  15  has terminals  15   a,    15   b.  Electrically conductive cable  16  has terminals  16   a,    16   b.  Electrically conductive cable  15  has terminal  15   a  connected to power converter circuit&#39;s  1  positive differential load sense terminal  1   f,  and terminal  15   b  is connected to output load&#39;s  90  positive differential terminal  90   a.  Electrically conductive cable  16  has terminal  16   a  connected to power converter circuit&#39;s  1  negative differential load sense terminal  1   g,  and terminal  16   b  is connected to output load&#39;s  90  negative differential terminal  90   b.    
         [0171]    The embodiment of the present invention shown in  FIG. 5  includes additional terminals and connections for fault limit circuit  71  connected within the secondary power circuit  60 . In addition to those terminals and connections previously mentioned herein, fault limit circuit  71  has load over-voltage fault input terminal  71   c.  Also, in addition to over-voltage fault types in  FIG. 4  previously described herein, the embodiment of the present invention shown in  FIG. 5  has a load over-voltage type fault signal, which upon its issuance is received by fault limit circuit  71 , which subsequently acts in the same manner previously described herein for other over-voltage type faults, causing the switching actions of MOSFET switching device one  43  and MOSFET switching device two  45  to cease, and resulting in them being maintained in high impedance states corresponding to their off-states. Resetting the latched off condition requires first removing, then restoring of AC mains supply power at power converter circuit&#39;s  1  line terminal  1   a,  just as in the case of over-voltage faults herein previously described. 
         [0172]    The embodiment of the present invention shown in  FIG. 5  includes load over-voltage sensor  72  connected within the secondary power circuit  60 . Load over-voltage sensor  72  has positive differential load terminal  72   a,  negative differential load terminal  72   b,  positive differential output terminal  72   c,  and negative differential output terminal  72   d.  Load over-voltage sensor  72  has its positive differential load terminal  72   a  connected to secondary power circuit&#39;s  60  positive differential load sense terminal  60   j.  Load over-voltage sensor  72  has its negative differential load terminal  72   b  connected to secondary power circuit&#39;s  60  negative differential load sense terminal  60   k.  Load over-voltage sensor  72  has its positive differential output terminal  72   c  connected to fault circuit&#39;s  71  load over-voltage input terminal  71   c,  and its negative differential output terminal  72   d  connected to fault circuit&#39;s  71  signal ground terminal  71   e,  output over-voltage sensor&#39;s  69  negative differential output terminal  69   d  and negative differential load terminal  69   b,  transformer over-voltage sensor&#39;s  70  negative differential output terminal  70   d,  control circuit&#39;s  66  ground terminal  66   e,  secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  voltage sensor&#39;s  68  negative differential output terminal  68   d  and negative differential load terminal  68   b,  and secondary power circuit&#39;s  60  input ground terminal  60   c.    
         [0173]    In addition to those sensed variables for which signals are received by fault limit circuit  71  described herein for the purpose of fault detection and fault limit control in  FIG. 4 , the embodiment of the present invention shown in  FIG. 5  causes a fault limit circuit  71  to generate a fault signal on its positive differential output terminal  71   d  when the differential voltage of output load  90 &#39;s positive differential terminal  90   a  with respect to negative differential terminal  90   b  exceeds an established maximum threshold value, and consequently a load over-voltage fault signal conducts from load over-voltage sensor&#39;s  72  positive differential output terminal  72   c  to fault limit circuit&#39;s  71  load over-voltage fault input terminal  71   c.  In this event, fault limit circuit&#39;s  71  fault shutdown terminal  71   d  conducts a fault signal to control circuit&#39;s  66  fault input signal terminal  66   j,  to which control circuit  66  acts with respect to this signal in the same manner herein described in the description of  FIG. 4  for other signals intended for purpose of fault limit and control, causing the switching actions of MOSFET switching device one  43  and MOSFET switching device two  45  to cease, and resulting in them being maintained in high impedance states corresponding to their off-states. Resetting the latched off condition requires first removing, then restoring of AC mains supply power at power converter circuit&#39;s  1  line terminal  1   a,  just as in the case of over-voltage faults herein previously described. 
         [0174]    The embodiment of the present invention shown in  FIG. 5  includes additional terminals and connections for control circuit  66  connected within the secondary power circuit  60 . In addition to those terminals and connections previously mentioned herein, control circuit  66  has load voltage monitor input signal terminal  66   i.    
         [0175]    The embodiment of the present invention shown in  FIG. 5  includes load voltage sensor  73  connected within the secondary power circuit  60 . Load voltage sensor  73  has positive differential load terminal  73   a,  negative differential load terminal  73   b,  positive differential output terminal  73   c,  and negative differential output terminal  73   d.  Load voltage sensor  73  has its positive differential load terminal  73   a  connected to secondary power circuit&#39;s  60  positive differential load sense terminal  60   j,  and load over-voltage sensor&#39;s  72  positive differential load terminal  72   a.  Load voltage sensor  73  has its negative differential load terminal  73   b  connected to secondary power circuit&#39;s  60  negative differential load sense terminal  60   k,  and load over-voltage sensor&#39;s  72  negative differential load terminal  72   b.  Load voltage sensor&#39;s  73  positive differential output terminal  73   c  is connected to control circuit&#39;s  66  load voltage monitor input signal terminal  66   i.  Load voltage sensor&#39;s  73  negative differential output terminal  73   d  is connected to control circuit&#39;s  66  signal ground terminal  66   e,  fault limit circuit&#39;s  71  signal ground terminal  71   e,  load over-voltage sensor&#39;s  72  negative differential output terminal  72   d,  output over-voltage sensor&#39;s  69  negative differential output terminal  69   d  and negative differential load terminal  69   b,  transformer over-voltage sensor&#39;s  70  negative differential output terminal  70   d,  control circuit&#39;s  66  ground terminal  66   e,  secondary capacitor&#39;s  62  negative differential terminal  62   b,  secondary full wave current rectification elements&#39;  61  negative differential output terminal  61   d,  secondary power circuit&#39;s  60  negative differential output terminal  60   i,  voltage sensor&#39;s  68  negative differential output terminal  68   d  and negative differential load terminal  68   b,  and secondary power circuit&#39;s  60  input ground terminal  60   c.    
         [0176]    In addition to those sensed variables of current and voltage previously described herein for the preferred embodiment shown in  FIG. 3 , and received by control circuit  66  for the purpose of output variable regulation, the embodiment of the present invention shown in  FIG. 5  has a load voltage sense signal generated by load voltage sensor&#39;s  73  positive differential output terminal  73   c  and conducted to control circuit&#39;s  66  load voltage monitor input signal terminal  66   i,  to which control circuit  66  acts with respect to this signal in the same manner herein described in the description of  FIG. 3  for other signals intended for purpose of output variable regulation. 
         [0177]    The present invention can be used as a stand-alone power conversion system capable of supplying efficient power to an output load, whether for instance as a system capable of charging various high or low voltage batteries as its load, efficiently powering an LED load which is efficacious for illumination purposes, or as part of a modular system where it produces a fractional share of the total output power. The present invention can be used also as a stand-alone power conversion system, or constituent of a power system where the expected benefit of reduced size, weight, or manufacturing cost results due to lower maximum working voltage magnitudes in secondary circuits. It will find applicability in numerous areas, including power conditioning, power conversion, power regulation, power backup and redundancy, and power isolation. 
         [0178]    The invention having been thus described, it will be obvious that the same may be varied in many ways, not only in construction but also in application. Such variations are not to be regarded as a departure from the spirit and scope of the invention, but rather as modifications intended to be encompassed within the scope of the claims.