Rectifier assembly

A rectifier assembly (20) for rectifying an AC voltage into a DC voltage has at least one first terminal (21, 22, 23), a second terminal (24) and an intermediate circuit (50). The first terminal (21, 22, 23) is connected via a circuit (31, 32, 33) to a neutral point (40), and the second terminal (24) is connected to the neutral point (40). The circuit arrangement (31, 32, 33) has a first branch (81) and a second branch (82) connected in parallel with the first branch (81). Both branches (81, 82) comprise a changeover arrangement (92, 93) and a coil (91, 94) connected in series with the changeover arrangement. The coil (91) in the first branch (81) is on the side of the changeover arrangement (92) averted from the neutral point (40), and the coil (94) in the second branch (82) is on the side facing the neutral point (40).

BACKGROUND

Field of the Invention

The invention relates to a rectifier assembly.

Related Art

US 2015/0061606 A1 discloses a rectifier for generators with different speeds and a plurality of passive rectifiers, which are connected in series.

U.S. Pat. No. 5,952,812 A discloses an inductance or coil, which is connected in parallel with the input terminals of a rectifier.

US 2010/0220501 A1 discloses a rectifier which, on the output side, is connected to two parallel-connected inverters, which inverters respectively supply an associated transformer.

EP 2 567 857 A1 discloses an interconnection of all the phases of a voltage converter by means of a switching mechanism.

EP 0 660 498 A2 discloses a Vienna rectifier and the mode of operation thereof.

One object of the invention is the provision of a novel rectifier assembly and a novel vehicle having such a rectifier assembly.

SUMMARY

A rectifier assembly for the rectification of an AC voltage into a DC voltage comprises at least a first terminal, a second terminal and an intermediate circuit. The intermediate circuit comprises a first conductor, a second conductor and at least one capacitor between the first conductor and the second conductor. The at least one first terminal is connected via an associated circuit arrangement to a neutral point, and the second terminal is likewise connected to the neutral point. The circuit arrangement comprises a first branch and a second branch, which second branch is connected in parallel with the first branch, which first branch and second branch respectively comprise a changeover arrangement and a coil connected in series with said changeover arrangement, which coil in the first branch is provided on the side of the changeover arrangement which is averted from the neutral point, and which coil in the second branch is provided on the side of the changeover arrangement which faces the neutral point, which changeover arrangements respectively comprise at least one controllable switch and permit a current flow between the associated branch and the intermediate circuit, wherein, in a first state Z1of the at least one controllable switch, a current flow between the first terminal and the neutral point via the changeover arrangement is suppressed, and wherein, in a second state Z2of the at least one controllable switch, a current flow between the first terminal and the neutral point via the changeover arrangement is possible.

By means of the two branches, which are mutually inverted with respect to the arrangement of the coil, novel possibilities come about in that, via one of the first terminals, in a preselected half-wave, the intermediate circuit can be energized from both above and below. This permits the achievement of a smaller ripple current, and also provides advantages with respect to any discharge currents occurring.

The rectifier assembly may comprise at least three first terminals that are connected to the neutral point via the respectively associated circuit arrangement. A triple-phase current can also be processed via three first terminals.

According to one embodiment, the rectifier assembly may comprise at least two first terminals that are connected to the neutral point via the respectively associated circuit arrangement, and the at least two first terminals may be interconnected electrically. The electrical connection or parallel connection of the circuit arrangements enables the total current on the at least two first terminals to be divided, and the circuit arrangements can thus be rated for lower maximum currents or maximum capacities.

The rectifier assembly may comprise a single first terminal. This is sufficient for a single-phase supply network.

The rectifier assembly may comprise a control device that is configured to influence the at least one controllable switch and thus can influence the operation of the rectifier assembly.

The control device may be configured for at least temporary pulsed actuation of the at least one controllable switch, such as by means of a PWM signal. The pulsed actuation enables the current injected into the intermediate circuit to be specified accurately.

According to one embodiment, the control device may be configured to simultaneously switch the at least one controllable switch of the first branch and the at least one controllable switch of the second branch of one of the least one first terminals, at least temporarily, to the first state. This permits an at least approximately symmetrical supply of the intermediate DC circuit, and thus a reduction of ripple currents in the intermediate circuit.

The control device may be configured, on one of the at least one first terminals, at least temporarily, to set the at least one controllable switch of the first branch to the first state Z1, and to set the at least one controllable switch of the second branch to the second state Z2, or vice versa. An asymmetrical supply of the intermediate circuit by means of this first terminal is accordingly possible. Optionally, this can be combined with an asymmetrical supply of one of the other first terminals.

At least one of the changeover arrangements may comprise a bridge rectifier. The bridge rectifier may comprise two bridge rectifier terminals, a first output, a second output and the at least one controllable switch. The bridge rectifier terminals may be connected to the associated branch. The first output is connected to the first conductor and the second output may be connected to the second conductor. The bridge rectifier may be configured:in the first predefined state Z1of the at least one controllable switch, to permit a current flow from at least one of the bridge rectifier terminals to the first output, but to prevent a current flow from the first output to the bridge rectifier terminals,in the first predefined state Z1of the at least one controllable switch, to permit a current flow from the second output to at least one of the bridge rectifier terminals, but to prevent a current flow from the bridge rectifier terminals to the second output,in the first predefined state Z1of the at least one controllable switch, to suppress a current flow between the two bridge rectifier terminals, andin the second predefined state Z2of the at least one controllable switch, to permit a current flow between the two bridge rectifier terminals, in at least one direction. The employment of a bridge rectifier permits a preferred configuration of this functionality.

According to one embodiment, the bridge rectifier terminals may be connected respectively via a diode to a first point, and connected via a diode to a second point. The first point may be connected via a diode to the first output, and the second point may be connected via a diode to the second output. The configuration of the bridge rectifier with diodes permits a bridge rectifier circuit that is reliable in operation.

The at least one controllable switch may comprise a first controllable switch that is connected between the first point and the second point. The first controllable switch is non-conducting in the first state Z1and is conducting in the second state Z2such that, in the second state Z2, a connection is constituted between the first point and the second point. This solution permits a cost-effective configuration with a smaller number of controllable switches.

In one embodiment, the at least one controllable switch comprises a second controllable switch and a third controllable switch. The two bridge rectifier terminals of this embodiment may comprise a first bridge rectifier terminal and a second bridge rectifier terminal. The second controllable switch may be connected between the first bridge rectifier terminal and the first point, and the third controllable switch is connected between the first bridge rectifier terminal and the second point. This configuration requires additional switches. However, the power loss is lower, such that the circuit is particularly advantageous for high-capacity rectifiers.

According to one embodiment, the first bridge rectifier terminal is the bridge rectifier terminal that is assigned to the associated coil.

According to one embodiment, the second bridge rectifier terminal is the bridge rectifier terminal that is assigned to the associated coil.

According to one embodiment, the rectifier assembly comprises a network filter that permits a discharge current. The employment of a network filter of this type improves the EMC properties of the entire circuit, and the optimization by means of an appropriate setting of the controllable switch has a positive effect.

A vehicle that is configured as an electric vehicle or a hybrid vehicle may have a corresponding rectifier assembly. High-capacity rectifier assemblies are required in vehicles, and the rectifier assembly described, notwithstanding its high capacity, features comparatively low discharge currents.

According to one embodiment, the vehicle comprises a connector for the connection of a charging cable for the vehicle and, at least temporarily, a galvanic coupling is constituted between the terminals of the connector and the rectifier assembly. The vehicle may comprise a traction battery and, at least temporarily, a galvanic coupling is constituted between the terminals of the connector and the traction battery. In configurations of this type, discharge currents in the rectifier assembly also act externally to the vehicle, as no galvanic isolation is constituted.

Further details and advantageous further developments of the invention proceed from the exemplary embodiments described hereinafter and represented in the drawings, which are not to be understood by way of any limitation of the invention, and from the sub-claims.

DETAILED DESCRIPTION

FIG. 1shows a rectifier assembly20for the rectification of an AC voltage into a DC voltage. The rectifier assembly20comprises a first terminal21, a second terminal22, a third terminal23and a fourth terminal24. The rectifier assembly20has an intermediate circuit50with two capacitors61,62, a first conductor51, a second conductor52and a node point53. The node point53is connected via the first capacitor61to the first conductor51, and via the second capacitor62to the second conductor52. The capacitors61,62are preferably intermediate circuit capacitors for the storage and release of energy in the intermediate circuit50, and have an appropriate capacitance for the respective application instance. In the exemplary embodiment, the intermediate circuit is configured as an intermediate DC voltage circuit. The first terminal21, the second terminal22and the third terminal23are respectively connected via an associated circuit arrangement31,32,33to a neutral point40, and the fourth terminal24is also connected to the neutral point40. The neutral point40is connected to the node point53. Preferably, the rectifier assembly20additionally comprises a fifth terminal25, via which a protective conductor PE (standing for “protective earth”) of the supply network is connectable. On the fifth terminal25, symbolically, a protective conductor symbol69is provided, which is symbolically employable in the rectifier assembly20, in which the reference number69is also applied thereto. The use of a supply network with no protective conductor PE is also possible. Networks of this type are described as IT networks. The supply network can also be described as a network connection.

The circuit arrangements31,32,33are respectively configured to permit a current flow between the circuit arrangement31,32,33, on the one hand, and the first conductor51or the second conductor52on the other hand. Insofar as the present application describes a current flow between two points, this does not imply any statement as to the direction of the current flow. For the charging of the capacitors61,62, a current preferably flows from the circuit arrangements31,32,33to the first conductor51, and a current flows from the second conductor52to the circuit arrangements31,32,33. The first conductor51thus assumes a higher potential than the second conductor52.

The connection between the neutral point40and the node point53is advantageous if a neutral conductor is connected to the fourth terminal24, as this results in a reference potential between the neutral conductor and the node point53. The rectifier assembly20would also function in the absence of the connection between the neutral point40and the node point53. If no neutral conductor is present on the fourth terminal24, the variant with no connection between the neutral point40and the node point53can be advantageous, on the grounds of lower discharge currents. The potential on the node point53, in the absence of this connection, is not fixed to a predefined potential on the terminal24, but can vary. This is described as “free floating”, and there is thus constituted no fixed relationship with a predefined potential. In the USA, for example, a neutral conductor is not present in some cases.

Alternatively, if no connection is provided between the neutral point40and the node point53, the capacitors61,62can be replaced by a single capacitor.

Mode of Operation

Different network connections exist, and the rectifier assembly20preferably operates with the greatest possible number of variants of network connections.

FIG. 2, by way of an example, shows the customary supply network10in central Europe, which is configured as a TN system with three phases L1, L2and L3, which are provided on associated terminals11,12,13, and having a neutral point14′ as neutral conductor. The three phases L1, L2, L3are supplied by the AC voltage sources17, which have a respective phase difference of 120°. In the embodiment represented, the neutral conductor (N)14′ is grounded, and thus also functions as protective conductor (PE). This is described as a PEN conductor. Many other network connections also have a neutral conductor, but not all. In an intermediate station18, for example a house or a charging station, the PEN terminal14′ is customarily divided into a neutral conductor terminal (N)14and a protective conductor terminal (PE)15. The terminals11,12,13,14,15can be connected to the terminals21,22,23,24,25, in order to operate the rectifier assembly20. To this end, for example, a connector16is provided in a vehicle, via which the terminals21to25are directly or indirectly connected to the supply network10. The terminals21to24, which are responsible for actual current conduction, are also described as live terminals21to24.

In a central European single-phase network, on the grounds of ambiguous plug connectors in countries such as Germany, there is no explicit association between the phase terminal L1and the neutral conductor terminal N, and the phase terminal L1can either be connected to the first terminal21and the neutral conductor terminal N to the fourth terminal24, or vice versa. The protective conductor PE is connected to the fifth terminal25. Either the explicit association can be established by an upstream circuit, or the rectifier assembly20is configured to operate with both variants. If the rectifier assembly is not intended for use in a triple-phase network, the second terminal22and the third terminal23, together with the associated circuit arrangement32,33, can be omitted. The neutral point40can still be described, in analogous terms, as the neutral point40, or in general terms as the point40.

Conversely to a supply network10with a neutral conductor, the US supply network, for example, described by the term “split phase”, comprises a first phase terminal and a second phase terminal, wherein the phase of the second phase terminal is phase-displaced by 180° in relation to the phase of the first phase terminal. The first phase terminal is designated as HOT1, and the second phase terminal as HOT2. A neutral conductor can be provided, but is not always provided. In many cases, a protective conductor PE is provided. In a supply network with no neutral conductor, the first phase terminal HOT1can be connected to one of the terminals21,22,23, or—for the reduction of currents in the circuit arrangements31,32,33—to all three terminals21,22,23, and the second phase terminal HOT2can be connected to the fourth terminal24. Thus, for example, rather than a neutral conductor, the phase terminal HOT2, which has a phase difference of 180° in relation to HOT1, would be connected to the fourth terminal24.

FIG. 3shows an exemplary embodiment of the circuit arrangement31, which can be applied in the same manner for the circuit arrangements32,33.

The circuit arrangement31, between the first terminal21and the neutral point40, comprises a first branch81and a second branch82which is connected in parallel with the first branch81. Additionally, an—unrepresented—third branch in the form of an X-capacitor can be provided between the first terminal21and the neutral point40.

By way of distinction from a Vienna rectifier, the present rectifier is described as a Weissach rectifier or a Weissach rectifier assembly.

The first branch81and the second branch82respectively comprise a changeover arrangement92,93and a coil91,94which is connected in series with the changeover arrangement92,93, wherein the coil91in the first branch is provided on the side of the changeover arrangement92which is averted from the neutral point40, and wherein the coil94in the second branch82is provided on the side of the changeover arrangement93which faces the neutral point40. In the first branch81, this arrangement can also be described as a Vienna cell, and in the second branch as the reverse or inverse Vienna cell.

The changeover arrangements92,93respectively comprise at least one schematically represented controllable switch110, and permit a current flow between the associated branch81,82and the intermediate circuit50, or the first conductor51and/or the second conductor52thereof. The changeover arrangements92,93respectively comprise a first changeover arrangement terminal102and a second changeover arrangement terminal113, by means of which they are connected to the associated first branch81or second branch82.

The at least one controllable switch110is preferably an electronic switch, wherein a semiconductor switch is further preferred. For example, semiconductor switches of the MOSFET or IGBT type are appropriate.

A control device99is provided for the actuation of the changeover arrangements92,93, or particularly of the controllable switch110.

In a first state Z1of the at least one controllable switch110, a current flow between the first terminal21and the neutral point40via the changeover arrangement92or93is suppressed and, in a second state Z2of the at least one controllable switch110, a current flow is possible between the first terminal21and the neutral point40via the changeover arrangement92,93.

By the changeover of the at least one controllable switch110to the second state Z2, a current is permitted between the terminal21and the neutral point40, wherein the direction of the current flow is dependent upon the present value of the AC voltage (phase) on the first terminal21. If the voltage on the first terminal21is more positive than the voltage on the neutral point40and the switch110of the changeover arrangement92assumes the second state Z2, a current flows from the first terminal21via the coil91and the changeover arrangement92to the neutral point40. The current in the coil91rises over time, and energy is stored in the magnetic field of the coil91. If the switch110is then switched to the first state Z1, the associated coil91or94can release the stored energy to the intermediate circuit50via the changeover arrangement92or93.

In a conventional Vienna rectifier which, for example, comprises only the first branch81and no second branch82on the first terminal21, the energy stored in the coil91—depending upon whether the positive or negative half-wave is present on the first terminal or the direction in which energy has been stored in the coil—is either used for the first branch51only or for the second branch52only. The provision of the additional second branch82, wherein the coil is arranged on the right-hand side in relation to the changeover arrangement93, respectively permits either the first conductor51to be (positively) supplied via the upper branch81and the second conductor52to be (negatively) supplied via the lower branch82, or the first conductor51to be (positively) supplied via the lower branch82and the second conductor52to be (negatively) supplied via the upper branch81. Additional options for the supply of the intermediate circuit50are obtained accordingly and, in both a single-phase supply network and a triple-phase supply network, a DC voltage can be generated on the intermediate circuit50which varies less than in the absence of the lower branch82. This effect has been observed to be particularly positive in a single-phase supply network, wherein the ripple current on the intermediate circuit can be significantly reduced. In a triple-phase supply network, the voltage variation on the intermediate circuit is already significantly smaller than in a single-phase supply network, such that the action of this effect is proportionally reduced.

The control device99preferably comprises an—unrepresented—voltage measuring device for the measurement of the respective voltage on the terminals21,22,23(phases). It is further preferred if the control device99comprises one or more of the following devices:A voltage measuring device for the measurement of voltage on the node point53,A voltage measuring device for the measurement of voltage on the intermediate circuit50,A current measuring device for the measurement of current on the intermediate DC circuit,A current measuring device for the measurement of the respective current of the circuit arrangements31,32,33on the first conductor51and on the second conductor52.

For the achievement of a good power factor, the control device99actuates the circuit arrangements31,32,33or the changeover arrangements92,93such that the current of the phase voltage follows the respective phase.

Given that a circuit arrangement31,32,33is provided on each of the terminals21,22,23, an infeed to the first conductor51and/or to the second conductor52can be executed on each of the terminals during both the positive half-wave and the negative half-wave. This permits a variety of combinations, which are not possible in a simple Vienna rectifier.

FIG. 4shows an exemplary embodiment of the changeover arrangement92, wherein the same design can be employed for the changeover arrangement93. The changeover arrangement92is configured in the manner of a Vienna rectifier.

The changeover arrangement92comprises a first changeover arrangement terminal102, a second changeover arrangement terminal113, a first output96and a second output97. The changeover arrangement terminals102,113can also be described as bridge rectifier terminals, and their function is to connect to the associated first branch81or second branch82. The function of the first output96is to connect to the first conductor51, and the function of the second output97is to connect to the second conductor52.

The changeover arrangement92comprises a bridge rectifier95and the controllable switch110, as described in greater detail hereinafter.

The changeover arrangement terminal102is connected via a diode103to a point104, and the point104is connected via a diode105to the first output96. The changeover arrangement terminal102is connected via a diode106to a point107, and the point107is connected via a diode108to the second output97. A controllable switch110is provided between the points107and104. Although, in the exemplary embodiment, the switch110is configured as a MOSFET, other exemplary electronic switches, such as IGBTs, are also possible. The changeover arrangement terminal113is connected via a diode111to the point104and via a diode112to the point107. The cathodes of the diodes103,105,106,108,111,112are respectively switched-in or switched to the first output96on the side of the first conductor51, and the anodes are respectively switched-in or switched to the second output97on the side of the second conductor52. The mode of operation of a Vienna rectifier is described, for example, in EP 0 660 498 A2.

If the controllable switch110is switched to a first non-conducting state Z1, the bridge rectifier95functions in the manner of a normal bridge rectifier. A current can flow from the changeover arrangement terminals102,113via the diodes103,105,111to the first output96, and a current can flow from the second output97via the diodes108,106,112to the changeover arrangement terminals102,113, as the corresponding diodes in these directions are switched to the forward direction.

If, conversely, the controllable switch110is switched to a second conducting state Z2, a current can flow from the changeover arrangement terminal102via the diode103, the controllable switch110and the diode112to the changeover arrangement terminal113or, conversely, a current can flow from the changeover arrangement terminal113via the diode111, the controllable switch110and the diode106to the changeover arrangement terminal102. In each case, moreover, a current can also flow from the changeover arrangement terminals102and/or113to the first output51, and/or a current can flow from the second output52to the changeover arrangement terminals102,113.

Whether a current actually flows is dependent upon the voltage ratios on the changeover arrangement terminals102,113and on the outputs96,97.

If the diodes103,104are arranged on the side of the coil91or94, the diodes111,112can be configured with a lower rating than the diodes103,104, as they are subject to a lower loading.

FIG. 5shows a further embodiment of the changeover arrangement92according toFIG. 4. This also comprises the changeover arrangement terminals102,113, the diodes103,105,106,108,111and112and the points104,107, which are identified by the same reference numbers as inFIG. 4. The switch110inFIG. 4has been replaced by two switches110A,110B. The switch110A is connected in parallel with the diode111, and the switch110B is connected in parallel with the diode112. The diodes111,112can be configured as integrated inverse diodes of the respective semiconductor switch110A,110B, or as additional parallel-connected diodes, preferably with a low flux voltage, for example a Schottky diode. Preferably, the coil91or94is respectively connected on the side of the bridge rectifier terminal102, such that the diodes103,106are on the side of the coil91or94. This permits a reduction of the current flowing in the switches110A,110B, and facilitates the commutation thereof. Additionally, in this embodiment, switches110A,110B without integrated inverse diodes can be employed, for example cost-effective IGBT switches. However, both variants are possible.

The switch110A, in the conducting second state Z2, permits a current flow from point104to the changeover arrangement terminal113, and the switch110B, in the conducting second state Z2, permits a current flow from the changeover arrangement terminal113to the point107.

In the first non-conducting state of the switches110A,110B, the changeover device92behaves in the manner of the changeover device92according toFIG. 4. In the second conducting state of the switches110A,110B, the changeover device92permits a current flow from the changeover arrangement terminal102via the diode103and the switch110A to the changeover device terminal113, or a current flow from the changeover arrangement terminal113via the switch110B and the diode106to the changeover device terminal102. Conversely to the embodiment according toFIG. 4, this circuit features lower transmission losses as, unlikeFIG. 4, two diodes are connected in series in the conducting switch110.

Conversely to the changeover device92according toFIG. 4, the changeover device92according toFIG. 5is asymmetrical with respect to the changeover device terminals102,113. The changeover device terminal113can be provided in the form of the bridge rectifier terminal113which is assigned to the coil91, or alternatively the changeover device terminal102. The second-mentioned variant (diodes103,106and the bridge rectifier terminal102on the side of the coil91) features the lower losses on the switches110A,110B.

FIG. 6shows a diagram of the simulated current on the upper and lower capacitors of the intermediate circuit in the rectifier assembly20and, by way of comparison, in a corresponding Vienna rectifier. The simulation has been executed with the following marginal conditions:

Supply network: US split-phase with HOT1, HOT2and a frequency of 60 Hz

Capacitance of the capacitors of the intermediate circuit: upper capacitor: C_O=1.3 mF, and lower capacitor: C_U=1.3 mF

Voltage on the intermediate circuit: U=800 V

The diagram shows the respective current. A current greater than zero corresponds to an infeed of energy to the respective capacitor, and a current lower than zero corresponds to an output of energy from the respective capacitor.

The curves131or132show the current in the upper capacitor of the intermediate circuit or in the lower capacitor of the intermediate circuit, in a Vienna rectifier. In each case, power is supplied either to the upper capacitor or to the lower capacitor. It will be seen that the respective capacitor which is not supplied by the source is discharged. Accordingly, during the time in which it is supplied, it must be charged with double the power. The maximum positive current is approximately 73 A, and the maximum negative current is approximately −26 A.

The curves133,134overlap, and show the current in the upper capacitor of the intermediate circuit or in the lower capacitor of the intermediate circuit, in a Weissach rectifier20. In the simulation, the connection between the neutral point40and the node point53according toFIG. 1has been omitted, as this is advantageous for the US split-phase supply network employed. By means of the circuit arrangements31,32,33, it is possible to charge both the upper capacitor61and the lower capacitor62respectively, according toFIG. 1. As a result, the requisite current can be reduced by the capacitors61,62, whilst maintaining the same electrical output power. The maximum positive current is approximately 25 A, and the maximum negative current is approximately −25 A.

The r.m.s. value (root mean square value) of the current in the intermediate circuit capacitors is 34 A in the Vienna rectifier, and 17 A in the Weissach rectifier. Therefore, the loading of the intermediate circuit50, in the event of single-phase charging, is significantly lower in the Weissach rectifier20than in the Vienna rectifier. This permits a longer service life of the capacitors61,62.

FIG. 7shows a diagram of the simulated voltage on the intermediate circuit50, corresponding to the simulation according toFIG. 6.

The curves121or122show the voltage on the upper conductor of the intermediate circuit (corresponding to conductor51inFIG. 1) or on the lower conductor of the intermediate circuit (corresponding to conductor52inFIG. 1) of the Vienna rectifier. The maximum voltage is approximately 480 V, and the minimum voltage is approximately 300 V. This produces a voltage ripple of the order of 180 V.

The curves123,124, which are mutually overlapping, show the voltage on the upper conductor51and on the lower conductor52of the intermediate circuit of the Weissach rectifier20—c.f.FIG. 1. The maximum voltage is approximately 424 V, and the minimum voltage is approximately 376 V. This produces a voltage ripple of the order of 48 V.

As can be seen, the more consistent power injection associated with the Weissach rectifier20, in a US split-phase supply network, results in a lower fluctuation in voltage amplitude, or a reduced voltage ripple. The voltage ripple of the Weissach rectifier20is equivalent to approximately 27% of the voltage ripple of the Vienna rectifier.

As a result of the lower voltage ripple, for an equal average voltage, the minimum voltage of the Weissach rectifier20is greater than that of a Vienna rectifier. Consequently, for example, in a down-stream buck converter, a lower intermediate circuit voltage can be selected for a Weissach rectifier20than for a Vienna rectifier. This improves the efficiency of the buck converter, thereby resulting in a higher efficiency of the entire device.

FIG. 8shows a schematic representation of a vehicle19, in which the rectifier assembly20according toFIG. 1is provided. The vehicle can be, for example, a land vehicle, a watercraft or an aircraft. The first conductor51and the second conductor52are connected to a DC voltage converter (DC/DC converter)55, in order to supply the latter with energy from the intermediate circuit50. The DC voltage converter55is configured, for example, as a buck converter.

On the output of the DC voltage converter55, for example, conductors56,57and an EMC filter63are provided. The EMC filter63has an X-capacitor161, which is connected between the conductors56,57, a Y-capacitor162between the conductor57and the terminal25(the protective conductor PE) and a Y-capacitor163between the conductor56and the terminal25. Thereafter, the conductors56,57are respectively connected via an inductance164or165with conductors156or157. Thereafter, an X-capacitor166, which is connected between the conductors156,157, a Y-capacitor167between the conductor157and the terminal25(the protective conductor PE) and a Y-capacitor168between the conductor156and the terminal25are provided. The EMC filter63can also be configured with a multi-stage design.

The function of the Y-capacitors is to reduce interference voltages, which occur vis-à-vis the potential on the protective conductor terminal25. They customarily have a lower capacitance than the capacitors61,62according toFIG. 1. The reduction of interference voltages is achieved by the flow of a discharge current between the protective conductor terminal25and the conductor56or57. The function of the X-capacitors is the damping of the differential-mode interference voltage between the terminals56and57. Discharge currents from or to the protective conductor PE are applied across the EMC filter63.

The conductors156,157are connected to a load58, specifically a vehicle battery (traction battery) for a motor vehicle with an electric drive system, or, for example, a heating device. In the exemplary embodiment, in the part of the vehicle19represented, no transformer is provided. Customarily, motor vehicles having a charging device for a traction battery incorporate a transformer, and this results in galvanic separation between the external network and the components which are provided on the in-vehicle side of the transformer. As a consequence, discharge currents on the in-vehicle side of the transformer have no effect upon the side of the transformer which is external to the vehicle. Consequently, such discharge currents cannot result in the tripping of a network fuse. In the exemplary embodiment represented, conversely, no transformer and no galvanic separation is present and, in consequence, the reduction of discharge currents by a reduced fluctuation of the intermediate circuit voltage is advantageous.

FIG. 9shows a further embodiment of the rectifier assembly20, which is connected, for example, to a US split-phase supply network10. The supply network10makes the phases HOT1, HOT2and the protective conductor PE available. This is represented schematically by two AC voltage sources17, which are interconnected at a point117. The point117is simultaneously provided as a protective conductor terminal PE, with corresponding—and unrepresented—grounding.

The terminals21,22,23are interconnected by means of at least one conductor26, such that current can flow between HOT1and HOT2through all the circuit arrangements31,32,33. As a result, current flowing in the individual circuit arrangements31,32,33, is reduced, and these can be rated for lower maximum currents.

On a terminal of a US split-phase supply network, having a desired total charging capacity of 19.2 kW and an associated total current of the order of 80 A, the individual circuit arrangements, on the first three terminals, can be rated, for example, to 7.2 kW. At very high total capacities, further circuit arrangements can also be connected in parallel.

In a single-phase European terminal, the parallel circuit is also advantageously constituted by L1on the first terminals and N on the second terminal (or vice versa).

By definition, in the context of the present invention, numerous variations and modifications are possible.

In actual forms of embodiment, further components are preferably present, for example EMC filters, power factor controllers and/or insulation monitoring circuits.

On the terminals21,22,23, on the input side, additional filter coils can be provided, which are also described as interference suppression chokes. In general, EMC filters and network filters can additionally be provided on the input side.

In each case, the diodes can be replaced by switches which, depending upon the voltage on the respective switch, are switched to a conducting or a non-conducting state, and thus function in the manner of a diode. However, this is a complex arrangement, and the diodes are preferred.

By means of the present Weissach rectifier, high-power charging devices are possible. In charging devices with a triple-phase connection and a 400 V voltage amplitude, for example, a DC voltage of 800 V can be generated on the intermediate circuit50, and a power of 22 kW can be delivered.