Power management utilizing a high-frequency low voltage pre-charge and synchronous common coupling

The present disclosure relates to power management systems utilizing a high-frequency low voltage pre-charge. A power management system may comprise a low voltage power source, a power supply assembly connected to the low voltage power source, and a power module comprising a plurality of arrays. Each array may comprise a plurality of electrically isolated stacks connected through a synchronous common coupling. Each electrically isolated stack may comprise a plurality of stages, a multi-winding secondary, a pre-charge circuit connected to at least one of the plurality of stages, and a plurality of multi-winding isolated power supplies. Each multi-winding isolated power supply may be connected to one of the plurality of stages. The power supply assembly may be configured to supply charging current from the low voltage power source to at least one of the plurality of electrically isolated stacks.

BACKGROUND

The energy industry has depended solely on fossil fuels, but it is now shifting investment to develop new cheaper and cleaner energy sources not related to fossil fuels. Over the past two decades, renewable energy resources have been the focus for researchers, and many different power converters have been designed to make the integration of these types of systems into a distribution grid. As the power grid evolves, there will be more distributed power sources that are configured into microgrids. Microgrids operate with both utility (power network) and renewable power sources (solar, wind, battery, and/or other) with numerous various loads (single and three-phase). Medium, high, and extra high voltage electronic systems are needed to manage and control power flow as well as to assure power distribution quality in transmission lines such as applications for reactive power (“VAR”) compensators, voltage/frequency regulators, solid-state transformers (“SST”), solid-state power substations (“SSPS”), medium and high voltage direct current (“MVDC”/“HVDC”) drives, medium voltage alternate current drives (“MVD”), and others. Therefore, power electronic converters with these capabilities have the responsibility to carry out these tasks with high resiliency and efficiency. The increase in the world energy demands has necessitated the appearance of new power converter topologies and new semiconductor technology.

Electrical power networks produce and use real/active and imaginary/stored power. Typically, power lines carry active power (“KW”) and reactive power (“VAR”). The content of active and reactive power is expressed in power factor. As the total power flows through the line, both active and reactive power compete for capacity. VAR compensation is defined as the management of reactive power to improve the performance of alternate current (“AC”) power networks. The concept of VAR compensation embraces a wide and diverse field of both system and customer problems, especially related with power quality issues, since most power quality problems can be attenuated or solved with an adequate control of reactive power. In general, the problem of reactive power compensation is viewed from two aspects: load compensation and voltage support. In load compensation, the objectives are to increase the value of the network power factor, to balance the real power drawn from the AC supply, to compensate voltage regulation, and to eliminate current harmonic components produced by large and fluctuating nonlinear industrial loads. Voltage support is generally required to reduce voltage fluctuation at a given terminal of a transmission line. Reactive power compensation in transmission networks also improves the stability of the AC network by increasing the maximum active power that can be transmitted. It also helps to minimize variation at all levels of power transmission, it improves HVDC conversion terminal performance, increases transmission efficiency, controls steady-state and temporary over-voltages, and can avoid disastrous blackouts. VAR compensator systems can be electromechanical or static (“SVC”) and can be series or shunt reactive compensators. Series and shunt VAR compensation are used to modify the natural electrical characteristics of AC power networks. Series compensation modifies the transmission or distribution network parameters, while shunt compensation changes the equivalent impedance of the load. In both cases, the reactive power that flows through the network can be effectively controlled, improving the performance of the overall AC power network.

Conventional multi-level cascaded power management systems use a large three-phase 60 Hz transformer with multiple electrically isolated three-phase secondaries which may be phase shifted. These conventional systems supply power to electronic assemblies that convert the 60 Hz power feeding to a variable frequency (0 to 120 Hz) and voltage output. Each output may be implemented with an H-bridge and because these outputs are electrically isolated by the large 60 Hz transformer with isolated secondaries, the H-bridges can be connected in series or parallel. However, there is a need for more efficient systems over these existing Cascaded H-Bridge (“CHB”) topology.

CHB solutions are costly, complex, and unreliable because the designs are limited in switching frequency, dielectric, and thermal capability as well as requiring complicated hardware and cable assemblies. Traditionally, utilities avoid power electronic products due to cost, complexity, and lack of resiliency. In addition, these power electronic products require extra cost for installation because they are designed for operating in clean controlled environments. Within industry, many large motor applications would benefit from using power factor correction on constant speed motors, to save energy through VAR support, but most motor applications do not use power electronic solutions due to cost and reliability concerns. Due to renewable energy and the need for greater network resiliency, new electrical networks are emerging with multiple distributed energy sources rather than few large sources. The need for more flexible and efficient power flow control within a multi-source environment is well documented.

SUMMARY

According to some aspects, an exemplary power management apparatus utilizing synchronous common coupling comprises a synchronous common coupling, a plurality of ports, and a plurality of electrically isolated stacks connected through the synchronous common coupling. Each electrically isolated stack comprising at least one stage, with each stage comprising a source/load H-bridge, a flux H-bridge, and a direct current (DC) bus. The source/load H-bridge is connected to a source or load through one of the plurality of ports and the flux H-bridge is connected to an electrically isolated winding in the synchronous common coupling. The flux H-bridge is connected to the source/load H-bridge through the DC bus.

According to further aspects, an exemplary power management system utilizing synchronous common coupling comprises a plurality of ports, at least one array, and a central controller. The array comprises a plurality of electrically isolated stacks connected through a synchronous common coupling, each electrically isolated stack comprising a plurality of stages connected in series. Each stage comprises a stage controller, and the central controller configured to control and synchronize each stage controller to manage the power through the system.

According to further aspects, an exemplary power management system utilizing a high-frequency low voltage pre-charge comprises a low voltage power source, a power supply assembly connected to the low voltage power source, and a power module comprising a plurality of arrays, where each array comprises a plurality of electrically isolated stacks connected through a synchronous common coupling. Each electrically isolated stack comprises a plurality of stages, a multi-winding secondary, a pre-charge circuit connected to at least one of the plurality of stages, and a plurality of multi-winding isolated power supplies, with each multi-winding isolated power supply connected to one of the plurality of stages. The power supply assembly is configured to supply charging current from the low voltage power source to at least one of the plurality of electrically isolated stacks.

These and other features and aspects of the various aspects will become apparent upon reading the following Detailed Description and reviewing the accompanying drawings. Furthermore, other examples are described in the present disclosure. It should be understood that the features of the disclosed examples can be combined in various combinations. It should also be understood that certain features can be omitted while other features can be added.

DETAILED DESCRIPTION

The embodiments described herein are directed to high-frequency power electronics, more particularly multi-level and multi-port cascaded power management systems with significant improvement in cost, performance, part count, size, efficiency, and resiliency over existing CHB topology. In some embodiments, synchronous common coupling may be used to link the power flow between multiple electrically isolated and non-isolated alternating current/direct current (“AC/DC”) sources and loads to provide a hub for independent power flow control that is indifferent to voltage magnitude, frequency, and phase. Each power circuit may be provided with a synchronous common coupling to other power circuits to better control power, while maintaining electrical isolation between circuits.

According to embodiments described herein there are at least two different implementations of synchronous common coupling technology that may be implemented, single common flux core and high-frequency current bus. The single common flux core utilizes synchronous common coupling to exchange power directly between electrically isolated and non-isolated stages. The high-frequency current bus utilizes multiple high-frequency transformers to create a high-frequency current bus. The objective of synchronous common coupling is to instantly link power within bridge circuits internally to the CHB system while keeping electrical isolation. The bridge circuit may also be referred to herein as a “stage circuit,” “stage,” or “power circuit.” In a CHB topology system with synchronous common coupling, each stage behaves much better than conventional power circuits, acting as if it is powered by a three-phase source with capacitance contributed by all common stages in the system. In some embodiments, the power flows from one stage to another stage through the synchronous common coupling, providing each stage with three-phase power and energy storage from other stages to reduce the number of components and improve power flow efficiency, in order to exchange power within the power management system to support reactive power compensation and phase current balancing. In some embodiments, synchronous common coupling may be unidirectional and scalable, where a DC source may be coupled to the synchronous common coupling to provide more resiliency for network transients and inertia or stored energy for the conversion system, such as the cascaded multi-level and multi-port power management systems as described herein, to provide an internal hub for independent direct power flow control that is indifferent to voltage magnitude, frequency, and phase to the electrical network.

According to some embodiments, synchronous common coupling may be accomplished by synchronously switching (e.g., high-frequency switching>10 KHz) a flux H-bridge circuit (also referred to herein as “flux bridge”), giving each stage access to power from other stages, because the synchronous common coupling serves as a node to link power of the stages together while leaving the stages electrically isolated. Synchronous common coupling allows a standard CHB control method to control the source/load H-bridge to meet various objectives, while the flux bridges lower required capacitance with minimal additional control complexity. Synchronous common coupling assists each stage to meet its input requirements by supplementing available power to each stage by synchronously linking its DC bus to every other linked stage's DC bus. Since the DC bus voltage of each stage is the same value, and each stage receives a synchronous signal to control its flux bridge, the synchronous linkage enables power flow according to the coupling impedance between stages to keep DC bus voltage levels the same value without affecting electrical isolation requirements. The common coupling power flow capability between stages is determined by the coupling impedance, i.e. the lower the impedance the higher flow capability between stages. If resonant or soft switching techniques are used within the flux bridges, the impedances between stages may be very low. The stage control continues to operate its input bridge as required per the algorithm embedded within for the application, while absorbing or transmitting power through the synchronous flux bridge and linkage as required. Each stage control has on/off cycle control for its DC bus to provide a means to avoid undervoltage or overvoltage events and intrinsic power sharing.

According to some embodiments each stage may use high volume/low cost low voltage components (typically 1200V but in some cases 600V and 1700V), however, nothing prevents the use of higher voltage components if there are cost benefits. According to some embodiments, packaging of components may utilize discrete semiconductors on a printed circuit board with embedded power circuitry and stage controller to produce the small size and low cost. Operating at higher switching frequencies reduces magnetic component size and improve product performance. Controlling power without creating harmful levels of current and voltage harmonics is provided through digital isolation circuits that have high noise immunity. In some embodiments, each stage receives a common synchronous signal from an isolated source and contains energy storage within each stage, where energy is regulated by a stage controller within each stage that sends and receives energy, and periodically supplies or receives energy to a large energy network.

According to some embodiments, one or more stages may be connected together in a stack. A stack may be the similar to a controllable high voltage semiconductor H-bridge, but uses low cost and low voltage discrete semiconductors rather than expensive higher voltage semiconductor modules. The stack assemblies are more configurable and fault tolerant as well as having much lower Δv/Δt, stray parasitics, temperature variation capability, and overall higher efficiency than existing 3300V, 4500V, 6500V, and 10 kV commercially available semiconductor modules. According to some embodiments, a stack may be implemented with internal gate drive and power supplies so that they can be controlled by a digital control signal. This enables scalable higher power density and high-frequency operation with lower harmonics with less cost than other commercially available semiconductor module assemblies.

Synchronous common coupling significantly reduces part count and losses. It reduces the number of semiconductors, DC bus capacitance, and transformer cores, and number of windings. Using synchronous common coupling within CHB systems improves flexibility and reduces complexity by providing “true power router” capability. It enables multiple AC/DC cascaded sources and loads to efficiently share instantaneous power between phases, sources, and/or loads, indifferent to respective magnitude, frequency, phase, impedance, and other characteristics even during transient events. Another benefit of using CHB topology with synchronous common coupling, as described herein, is that it can be connected as a shunt or series regulator in various applications. It permits simple control strategies, enabling low cost and high efficiency. Synchronous common coupling may also provide advantages during commissioning, power up, and diagnostic modes. It can be tested prior to applying high voltage and surge current per switching element may be reduced due to power sharing, which also aides in pre-charging power circuits.

The embodiments described herein may provide significant advantages over existing state of the art electromechanical and power electronics power conversion products across a variety of applications, such as VAR compensation, power factor correction, voltage and frequency regulation, solid-state transformers, solid-state power substations, medium voltage AC drives, medium and high voltage DC transmission, test stands, and others. The embodiments described herein may be fault tolerant of poor network power quality and internal failures due to the many like stages connected in series, with each having its own stage controller for power flow and diagnostics.

The embodiments described herein may be implemented to compete in cost and resiliency with conventional products constructed of copper, iron, steel, aluminum, and paper. Systems utilizing embodiments described in this disclosure may be designed to be installed anywhere a transformer or switchgear is traditionally located. The embodiments described herein may be used in low, medium, and high voltage applications that require power flow control with galvanic isolation. The simplicity of the embodiments described herein result in reduced cost and higher resiliency, as well as achieving small size and high performance. In addition, the power circuits and components described in the embodiments may be submersed in high dielectric liquids to remove heat, protect the circuits from electrical or magnetic harm, and reduce both size and weight reducing overall cost while increasing reliability. Submersion may enable the components to be densely packaged and may provide better thermal and electrical properties than air. In medium and high voltage applications, submersion may enable stages and/or stacks from other sources to occupy adjacent space on a circuit board. Further, systems and com

Further, some components used by the embodiments described in this disclosure may be implemented with soft switching and DV/DT filters along with magnetic and electrostatic shields. Further, some embodiments may also be implemented with low parasitic capacitance and inductance to reduce electrical noise interference internally between circuits.

Other examples are described in the present disclosure. It should be understood that the features of the disclosed examples can be combined in various combinations. It should also be understood that certain features can be omitted while other features can be added.

FIG. 1depicts an example block diagram of a conventional multi-level cascaded power conversion circuit100, as is known in the art. The multi-level cascaded power conversion circuit100uses a large three-phase 60 Hz transformer with multiple electrically isolated three-phase secondaries (may be phase shifted) that supply power to electronic assemblies that convert the 60 Hz power feeding to a variable frequency (0 to 120 Hz) and voltage output. Each output is an H-bridge and because these outputs are electrically isolated by the large 60 Hz transformer with isolated secondaries, the H-bridges can be connected in series or parallel, referred to as a cascaded H-bridge (“CHB”) topology. Some CHB units may operate with bidirectional power flow up to 13.8 KV.

While traditional CHB topology has long been considered by industry as a possible solution three-phase AC solid-state transformer to replace traditional medium voltage transformers to achieve bi-directional power flow for multi-level cascaded power conversion, it is often too expensive to implement because large 60 Hz transformers with multi-winding secondaries, as shown inFIG. 1, are very expensive, heavy, and large, and products using them require a lot of customized assembly.

FIG. 2depicts a block diagram of one theoretical solution utilizing CHB topology where line and load are in phase (not intertwined). The path of the power for this example embodiment would be: AC1-DC-XFMR-DC-AC2. The main input power supplying power to AC1contributes directly in phase with output power AC2and all AC2outputs are connected in series that are powered by the same main input power and are utilizing separate and distinct transformers between each bridge circuit.

Another possible solution may comprise a CHB topology where the secondary H-Bridges are intertwined so that more than one phase contributes to the power generated on the output. The path of the power for this example embodiment would be: AC1-DC-XFMR-DC-AC2. However, in this version, the main input power supplying power to AC1contributes directly in phase with output power AC2, with each bridge circuit AC2output intertwined with AC2outputs from other main input power phases.

FIG. 3depicts a block diagram for another theoretical solution utilizing CHB topology that uses a common DC Bus. The path of the current for this example embodiment inFIG. 3would be: AC1-DC-XFMR-DC-CDC-AC2, where one phase of the three-phase main input power supplying power to AC1supplies power to a common DC bus (“CDC”), and for non-electrically isolated loads, common DC bus power is directly converted to AC by an output H-Bridge. The path of the current may also flow as follows: AC1-DC-XFMR-DC-CDC-DC-XFMR-DC-AC2, where the main input power supplying power to AC1supplies power to a common DC bus, and for electrically isolated loads/sources, common DC bus power is converted to AC through another electrically isolated bridge circuit.

However, the CHB solutions depicted inFIGS. 2 and 3suffer from limited flexibility, high part count, high cost, and high losses and thus have not been implemented by the industry. An important advantage of CHB topology is that it operates on a single-phase basis rather than three-phase, and this enables H-Bridges to be connected in series. However, the traditional CHB single-phase power input requires more DC bus energy storage than three-phase systems which increases part count, cost, losses, and size. Each bridge circuit only permits power sharing between other phases, sources, and loads indirectly on the circuit's inputs and outputs. This causes for power to flow through more circuitry (semiconductors) before it gets to where it needs to go, increasing losses and part count.

FIG. 4is a block diagram illustrating a cascaded multi-level and multi-port power management system400with synchronous common coupling440using a single common flux core450as the coupling path, according to some embodiments described herein. In the example embodiment shown inFIG. 4, a 6-port406A-F (also referred to herein generally as ports406) cascaded multi-level and multi-port power management system400may be implemented with6stacks420A-F (also referred to herein generally as stacks420) of multiple (N) stages430A-N (also referred to herein generally as stages430), with each stack420A-F connected to a respective port406A-F. Further, the stacks420A-F are coupled by a synchronous common coupling440using a single common flux core450as the coupling path. In the example embodiment, the stages430A-430N of each stack420may be connected in series, with the last stage430N of each stack connected to a neutral electrical connection, or “neutral”424. Each stack neutral424may be electrically independent or connected to one or more other stack neutrals424forming a group, and each neutral424or group of neutrals circuits within the power conversion system may be electrically floated and/or grounded by means of a solid conductor or one or more external network components such as a resistor, a inductor, or a capacitor.

FIG. 5is a block diagram illustrating a stage circuit assembly500, including a typical stage430, as described herein, connected to a source/load connection402and/or an adjacent stage through the stage ports502A-B, according to some embodiments described herein. The stage430may comprise the following sections: input filter520, a source/load bridge432, DC bus510, and a flux bridge434.

The input filter520may comprise an inductor/capacitor (“LC”) filter comprising the electrical components that prevent the stage430from injecting fast Δv/Δt transients into the electrical network, such as a capacitor522, inductors524,526, and transient suppressor528. The capacitor522and transient suppressor528in combination with the current regulating reactor404and inductors524/526may prevent electrical network transients from harming the stage430. According to some embodiments, the input filter520may be combined with a current regulating reactor404(as shown inFIG. 4) to create a filter to prevent voltage and current transients on the incoming power lines or loads from harming the stage430. The stage430may also have a current feedback504located as shown inFIG. 5, or elsewhere with the stage circuit assembly500, to provide feedback for regulating the network current through the stage. According to some embodiments, every stage430within a stack420may provide current feedback504. In other embodiments, only one stage430within the stack420may provide current feedback504for the other stages430since the current flowing through all series-connected stages430in a stack420will be the same value.

The source/load bridge432may comprise 2, 4, 6, or other number of switching devices that may be switched at high or low frequencies or a combination of both depending on the control strategy to regulate the network current. When high-frequency (>10 KHz) switching strategy is used, then fast silicon IGBTs or metal-oxide-semiconductor field-effect transistors (“MOSFETs”) or Wide Band Gap MOSFETs may be used depending on required cost, efficiency, and ratings. When low frequency switching (<1 KHz) is used, then low forward saturation silicon IGBTs are possible as well as IGBT and IGCT modules. For example, the sources/load bridge432may comprise four switches devices530A-D comprising insulated gate bipolar transistors (“IGBTs”) configured in a conventional H-bridge configuration, as shown inFIG. 5. In other embodiments, the switching devices may comprise integrated gate commutated thyristors (“IGCTs”), wide band gap (“WBG”) semiconductors, or other solid-state components in a half or full bridge, three-phase, or any other suitable configuration. The source/load bridge432may also be referred to herein as the “input H-bridge” or “output H-bridge.” The source/load bridge432is used to balance power throughout the stage430and regulates the DC bus510voltage while creating a low harmonic current waveform. In further embodiments, the DC bus510may comprise a DC bus capacitor508to provide a low inductance path for the switches, assist in minimizing DC bus ripple voltage, protect the switches from voltage transients, or the like. The source/load bridge432may provide wide input voltage variation to provide the regulated DC bus510.

The source/load bridge432uses (for example 1-20 kHz) pulse width modulate (“PWM”) switching to reduce current and voltage harmonics. When more than one stage430is used, the carrier frequency that generates the PWM switching may be phase shifted per each stage to effectively create a higher switching frequency than the actual PWM carrier—the more stages430A-N used, the higher the effective switching frequency. This technique may improve control and current waveform without penalizing the efficiency of the source/load bridge432.

According to embodiments, the power flows from one stage430to another stage430through the synchronous common coupling440. In some embodiments, this results in each stage430being provided with three-phase power and energy storage from other stages to reduce each stage requirements for DC bus capacitance. The network current (or power flow) of the stage430may be unidirectionally or bidirectionally controlled by the source/load bridge432, which uses one or more current regulating reactors per source or load to regulate network current or power flow by switching at least one source/load bridge432on/off. In some embodiments, if the DC bus510of the stage430does not have enough power to satisfy the network's current demands, then the DC bus510voltage begins to drop. However as the DC bus510voltage drops, other stages430can supply power to the DC bus510of that stage through the synchronous common coupling440.

In further embodiments, the source/load bridge432is designed to provide a bypass of the stage430in the case of a failed power component or some control failures. If the source/load bridge432fails to operate properly, the source/load bridge432is designed to naturally, or through positive control, deliberately turn on the power devices within the source/load bridge432continuously to short out the power input to stage430. In cases, where the stages430are connected in parallel, a means of disconnecting the failed stage430from other parallel healthy stages430may be provided, such as a fuse, contact, semiconductor, and/or the like. According to some embodiments, the switching devices of the source/load bridge432and the flux bridge434may have overcurrent sensing for protection.

Further, the source/load bridge432is controlled by a stage controller550to regulate current, DC bus voltage, and the power for the stage430, stack420, and array410to specified values. The source/load bridge432semiconductors530A-D may be switched at high or low frequencies or a combination of both depending on the control strategy to regulate the network current. When high-frequency (>10 KHz) switching strategy is used, then fast silicon IGBTs or metal-oxide-semiconductor field-effect transistors (“MOSFETs”) or Wide Band Gap MOSFETs may be used depending on required cost, efficiency, and ratings. When low frequency switching (<1 KHz) is used, then low forward saturation silicon IGBTs are possible as well as IGBT and IGCT modules.

Similarly to the source/load bridge432, the flux bridge434may comprise two, four or any other number of switching devices (IGBT, IGCT, WBG, etc.) in a half, full or other suitable topology bridge configuration. For example, the flux bridge434may comprise four switches devices540A-D comprising IGBTs configured in a conventional H-bridge configuration, as shown inFIG. 5. The flux bridge434may operate on a simple symmetrical duty cycle. The actual operating frequency may be determined by the type of device used.

The flux bridge434output may connect to an electrically isolated winding436located on high-frequency transformer core (for example 25 kHz to 250 kHz) in the synchronous common coupling440. If more than one stage430is used, the electrical winding436may be located on a common high-frequency transformer core. According to embodiments, the stage controller550for each flux bridge434circuit is synchronized so that power to the windings436of each stage430are in phase and at the same frequency. The power through the flux bridge434may be bi-directional. If so, the bridge rectifies the voltage and passes power to the DC bus510which is regulated by the source/load bridge432. The switching devices540A-D of the flux bridge434are switched synchronously with other flux bridges434of other stages430within each array410at high-frequency (e.g., >10 KHz) to reduce the size of the single common flux core450(or cores602) and the number of turns in the winding436of the synchronous common coupling440, as is further described herein.

In some embodiments, the flux bridge434may be soft-switched through a resonant capacitor514and/or inductor512connected in series with the windings436. In other embodiments, the flux bridge434may be may be hard switched, without the use of the resonant capacitor514and inductor512. In some embodiments, the flux bridges434of one or more stages430may temporarily change switching frequency to enable better power flow. In some embodiments, the current to the winding436may be monitored with a current shunt or an isolated current sensor by the stage controller550.

The stage controller550may control the switching devices530A-D and540A-D of the source/load bridge432and flux bridge434by switching them on and off utilizing PWM switching. The stage controller550may utilize an average current mode controlled power factor correction algorithm or the like. The stage controller550may comprise a DC-DC power supply powered by a wireless power supply which has a transmitter in the cell and a receiver (not shown) on the stage430, a DC-DC converter that receives its power from the DC bus510, or other power means. The power supply for the stage430may receive back-up power from control power of an adjacent stage when more than one stage430exists.

In some embodiments, the DC bus510may comprise DC bus capacitors508, a voltage feedback circuit506, and a DC-DC power supply. The voltage of the DC bus510may be regulated by the source/load bridge432via the stage controller550, and may be measured via a power resistor divider network. In some embodiments, the power management system may be implemented with digital isolation circuits560that have high noise immunity that may provide fast digital control from each stage430to a particular stage within a stack420.

According to some embodiments, the stage controller550may be implemented to direct the source/load bridge432to control the AC current. According to some embodiments, the stage controller550may comprise shunt resistors to measure the current. In some embodiments, the AC/DC input voltage may be measured at each stack420, at each stage430, or at the stage controller550. In some embodiments, if the incoming voltage is AC, the phase angle and a synchronized signal representing the zero crossing(s) may be communicated throughout the power management system400. In some embodiments, the stage controller550may comprise feedback sensors to detect temperature near the stage430, the stage controller550, the DC bus capacitor508, and/or the transformer winding436.

Referring again toFIG. 4, according to some embodiments, the power management system400may be implemented with a minimum of two ports406with the maximum number being unlimited. In the example 6-port system shown inFIG. 4, there are 6 ports406A-F (also referred to herein generally as ports406). In the example embodiment, each port406A-F is a bidirectional power port and may be connected to a power source or a load, as shown at402A-F. In some embodiments, the current harmonics may be minimized by means of a current regulating reactor404located between the port406A-F and the corresponding source/load connection402A-F. The current regulating reactor404may also provide protection from lightning or large fast network voltage transients.

According to some embodiments, the power management system400may be bidirectional through ports406such that the array is indifferent to whether a source or a load connection402is connected at each port406. As shown inFIG. 4, the power management system400may comprise of one array410, with three stages430in each of six stacks420A-F. A stack420may comprise one or more stages430connected in a series connection string422, according to some embodiments. An array410may comprise a group of two or more stacks420combined with a synchronous common coupling440. According to some embodiments, an array410may be connected in series and/or parallel with other arrays.

According to some embodiments, a stack420may be configured to control power bi-directionally at its configured input, which may also be an array port406, from the corresponding source/load connection402. According to some embodiments, if one stage430fails, the stack420may attempt to short its input by permitting the voltage to rise across the input enough for the semiconductors to fail shorted and the rest of the array410continues to operate through redundant stages430A-N within the series circuit, or stack420. If the internal failure occurs in such way that the whole or much more of the array410is damaged, then other redundancy measures are available such as configured parallel arrays410. Each stage430is provided with a means of synchronous common coupling440to other stage430to better control power, while maintaining electrical isolation between stages430. The cascaded multi-level and multi-port power management system400may operate in VAR compensation configuration, also referred to herein as a “shunt,” or in a power conversion configuration, also referred to here as “series” or “transformer” configuration, within the electrical network depending on application.

In some embodiments, the synchronous common coupling440utilizes a single common flux core450to exchange power directly between electrically isolated and non-isolated stages430A-N of the stacks420A-F, as shown in the example embodiment of the cascaded multi-level and multi-port power management system400inFIG. 4. The path of the power for this example embodiment would be: AC1-DC-COMMON FLUX CORE450. In other words, within each stage430, a port406(connected to source/load connection402) is connected to the source/load bridge432(which is referred to here as AC1) and input power is converted to “regulated DC voltage.” The regulated DC voltage is synchronized to the synchronous common coupling440by the flux bridge434and connected through the winding436to the common flux core450, which links the power to other stages430A-N in the system. There are multiple windings436wound on the single common flux core450, with each winding connected to a stage430, which creates the synchronous common coupling440. According to some embodiments, each array410in the power management system410may have its own synchronous common coupling440, such as the common flux core450shown inFIG. 4. In other embodiments, the power management system410may comprise multiple arrays410, each having separate synchronous common couplings440or multiple arrays sharing a same synchronous common coupling.

In power management systems400utilizing a single common flux core450, high-frequency flux travels within the core450to other windings436distributed on the single common flux core450. For resonant operation, the synchronous common coupling440behaves best for lowest leakage flux values and smallest leakage variation in the single common flux core450. In some embodiments, an external inductor may be used in high-frequency power supply circuits to minimize the effects of leakage variation. In some embodiments hard switching the flux bridge434and windings436may be used.

FIG. 6is a block diagram illustrating a cascaded multi-level and multi-port power management system600with the synchronous common coupling440comprising multiple high-frequency transformers to create a high-frequency current bus620, according to some embodiments described herein. As shown inFIG. 6, an exemplary cascaded multi-level and multi-port power management system600may comprise six ports406A-F with one array410. According to some embodiments, the power management system600may be implemented with one transformer602per stage430. In some embodiments, multiple stages430A-N may utilize a single transformer602with a single core and separate windings for each stage, combining the features of both the single common flux core450and the high-frequency current bus620.

For example, the cascaded multi-level and multi-port power management system600may be implemented in which the synchronous common coupling440utilizes multiple cores that exchange power directly between secondary windings connected together through the high-frequency current bus602and powered by electrically isolated stages430A-N. The path for power in this example embodiment would be: AC1-DC-XFMR-COMMON FLUX COUPLING. In other words, within each stage430, a port406(connected to a source/load connection402) is connected to the source/load bridge432(which is referred to here as AC1) and input power is converted to “regulated DC voltage.” The regulated DC voltage is synchronized to the synchronized common coupling440through the flux bridge434and connected to a transformer602with at least one primary winding436. A secondary winding604of the transformer602transfers the power to all stages430in the array610through the high-frequency current bus620, as shown inFIG. 6. According to some embodiments, the cascaded multi-level and multi-port power management system600may be implemented with the high-frequency current bus620utilizing selection and switching frequency to minimize leakage inductance and meet efficiency requirements.

According to some embodiments, multiple core systems may be implemented with a high-frequency current bus620flowing from primary winding436to secondary windings604through the core602to other stages430A-N via the secondary windings604which are connected in parallel within the array610. For resonant operation, the synchronous common coupling440behaves best for lowest leakage flux values and smallest leakage variation in the core602. In some embodiments, an external inductor may be used in high-frequency power supply circuits to minimize effects of leakage variation. In some embodiments, hard switching the flux bridge434and windings436may be used.

FIG. 7depicts a block diagram illustrating a multi-level and multi-port cascaded power management system700with synchronous common coupling440and a 3-port array710in a “coin” configuration, according to some embodiments described herein. According to some embodiments, the multi-level and multi-port cascaded power management system700may be implemented with one array710connected to a three-phase AC power network to act as a VAR compensator or “shunt regulator.” In other embodiments, this configuration may be utilized for line balancing, transformer impedance matching, or the like.

As shown inFIG. 7, an exemplary array710may comprise three stacks420A-C, where each stack420comprises of multiple stages430A-N, and each stack420is connected in series. In other embodiments, the number of stages430, stacks420, and arrays710used to form a power management system may depend on the network operating voltage and power. According to further embodiments, in a multi-level cascade converter, each stage430may contribute to the voltage and power on a single-phase basis, where the actual voltage and power rating of the array710depends on the number of stages430A-N used and at what power and voltage each one is utilized. According to some embodiments, the voltage of the multi-level and multi-port cascaded power management system700may be normally distributed evenly, whereas the power contribution may also be the same or vary.

FIGS. 8 and 9are block diagrams illustrating typical cascaded multi-level and multi-port power management systems800and900with synchronous common coupling440, according to some embodiments described herein.FIG. 8illustrates a cascaded multi-level and multi-port power management system800with synchronous common coupling440in a shunt application used for VAR compensation and line balancing, according to some embodiments described herein.FIG. 9illustrates a cascaded multi-level and multi-port power management system900with synchronous common coupling440in a series application to provide power flow control, according to some embodiments described herein. According to some embodiments, each cascaded multi-level and multi-port power management system800,900may be implemented with a 3-port system comprising one or more power module ports802A-C with multiple arrays830A-N in a series configuration. According to some embodiments, the power module810may be implemented with one or more arrays830A-N, one or more current regulating reactors404, and a high-frequency pre-charge and power supply assembly860. In some embodiments, each cascaded multi-level and multi-port power management system800,900may include network voltage and current feedback840and may comprise an enclosure with grounding provisions.

As shown inFIGS. 8 and 9, a multi-level and multi-port cascaded power management system800,900may further comprise a central controller850. According to some embodiments, the central controller850may coordinate operations of each stage430, stack420, and array410within the system to meet the network requirements. According to some embodiments, the central controller850may use average current mode controlled power factor correction algorithms, or the like. In some embodiments, numerous sources and loads may be connected within the power management system800,900, and there may be several power management systems operating with independent control, but working together as one large power management system which may be controlled by the central controller850to control power flow within the electrical network. In some embodiments, the central controller850is in communication with an energy network and may request to receive energy from the energy network. According to some embodiments, the central controller850may be configured to process and analyze the external network energy needs by either receiving requests from another entity, or determining requirements through evaluating current and voltage feedback magnitude, power factor, phase angle, harmonic content, sequence, frequency and other such characteristics feedback provided from the power flow within the external network.

FIG. 10is a block diagram illustrating a cascaded multi-level and multi-port power management system1000with a high-frequency pre-charge and power supply assembly860connected to a power module1010with multiple stacks420A-N comprising multiple stages430A-N, according to some embodiments described herein. According to some embodiments, the high-frequency pre-charge and power supply assembly860may provide power to each stage430A-N, stack420A-N, array410A-N, power module1010, and the cascaded multi-level and multi-port power management system1000from a low voltage power source1060to fully test the assembly prior to applying high power. According to some embodiments, the high-frequency pre-charge and power supply assembly860may be implemented by connecting a low voltage source (e.g. battery or auxiliary power) to supply charging current and stage control power to each stage430within an array410A-N.

According to some embodiments, the high-frequency pre-charge and power supply assembly860provides electrically isolated charging current to at least one DC bus510of one stage430within a stack420A-N, and power is distributed within the array410by the synchronous common coupling440to prevent inrush current to the DC bus510when high power is connected. According to some embodiments, the pre-charge circuitry1032may be implemented to maintain the proper voltage in the stages430during an outage indefinitely if power is lost on one or more sources, so that they are prepared to return to proper function immediately upon restoration of power.

According the some embodiments, the high-frequency pre-charge and power supply assembly860may be implemented with a high voltage cable powered by a secondary of the high-frequency current source switching regulator1050with an isolation transformer1042to provide high-frequency current to a high voltage conductor1046that shunts the transformer secondary1044. According to some embodiments, the high voltage conductor1046may serve as the primary winding1002to the cores1004with multi-winding secondaries mounted on each stack420A-N. Further, the primary windings1002and cores1004may provide isolated power to the stage controller550within each stage430A-N and pre-charge the pre-charge circuitry1032of at least one DC bus510of a stage430within each stack420A-N. The synchronous common coupling440may distribute and balance DC bus power throughout each stage430. According to some embodiments, at least one DC bus510of each stage430may be connected to the pre-charge circuitry1032such that all DC buses may be charged through the one stage430by the synchronous common coupling440.

In some embodiments, the cascaded multi-level and multi-port power management system1000may supply balanced or unbalanced power to any port via the high-frequency pre-charge and power supply assembly860. According to some embodiments, the system may comprise the addition of storage to give more flexibility in speed of response, which may emulate the inertia of synchronous machines. The higher the power, the more unbalance and regulation assistance the auxiliary, pre-charge, and a control port may provide. In some embodiments, the cascaded multi-level and multi-port power management system1000may reduce repair time because stages430A-N, stacks420A-N, arrays410A-N, power modules1010, and entire power management system assemblies can be tested anywhere by powering the pre-charge circuitry1032and high-frequency pre-charge and power supply assembly860with low voltage power from the low voltage power source1060.

It will be appreciated that cascaded multi-level and multi-port power management systems400,600,700,800,900, and100and power modules810,1010may comprise any number of arrays410, the arrays may comprise any number of stacks420, the stacks may comprise any number of stages430, and each system or component may comprise any number of ports, and they may be combined in various ways for various configurations of a power management system, according to the embodiments described herein.

Other aspects can comprise additional options or can omit certain options shown herein. One should note that conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain aspects comprise, while other aspects do not comprise, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more particular aspects or that one or more particular aspects necessarily comprise logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are comprised or are to be performed in any particular aspect.

The description is provided as an enabling teaching of the present devices, systems, and/or methods in their best, currently known aspects. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects described herein, while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present disclosure are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Thus, the description is provided as illustrative of the principles of the present disclosure and not in limitation thereof.

As used throughout, the singular forms “a,” “an” and “the” comprise plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a quantity of one of a particular element can comprise two or more such elements unless the context indicates otherwise. As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description comprises instances where said event or circumstance occurs and instances where it does not.

It should be emphasized that the above-described examples are merely possible examples of implementations and set forth for a clear understanding of the present disclosure. Many variations and modifications can be made to the above-described examples without departing substantially from the spirit and principles of the present disclosure. Further, the scope of the present disclosure is intended to cover any and all appropriate combinations and sub-combinations of all elements, features, and aspects discussed above. All such appropriate modifications and variations are intended to be comprised within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure.