Filter with y capacitors and variable damping for a 3-phase DC on-board electrical system

Abstract

The invention relates to a current converter (1, 1a, 1b) for an on-board electrical system (101) of an electrically driveable vehicle (100), comprising a first line (2) for a first potential (3), a second line (4) for a second potential (5), a third line (6) for a reference potential (7) and a filter unit (8), which has first to third connectors (10-12) connected to the first to third lines (2, 4, 6), a first capacitor (13) connected in a first current path (14) from the first to third connector (10, 12) and influencing a first impedance along the first current path (14) for diverting a common-mode current for the first and second line (2, 4) to the third connector (12), a second capacitor (15) connected in a second current path (16) from the second to the third connector (11, 12) and influencing a second impedance along the second current path (16) for diverting the common-mode current to the third connector (12), at least one resistance circuit (17, 18, 27) with a first and a second resistance component (19, 20), and a switch unit (21) which is designed such that, according to control information (22), by changing an interconnection of the resistance component (19, 20) within the filter unit (8), it switches between a first filter mode in which the first and second impedance is provided with a predefined value, and a second filter mode in which the first and second impedance is provided with an increased predefined value relative to the first filter mode.

Description

[0001] Power converter for an on-board power system of an electrically powered vehicle and on-board power system for an electrically powered vehicle

[0002] The present invention relates to a power converter for an on-board power system of an electrically driven vehicle, comprising a first line for a first potential, a second line for a second potential, a third line for a reference potential and a filter device which has a first terminal connected to the first line, a second terminal connected to the second line, a third terminal connected to the third line, a first capacitor connected in a first current path from the first terminal to the third terminal and influencing a first impedance along the first current path to divert a common-mode current related to the first and second lines to the third terminal, a second capacitor,which is connected in a second current path from the second terminal to the third terminal and influences a second impedance along the second current path for diverting the common-mode current to the third terminal, and a switching device which is configured to switch between a first filter mode and a second filter mode in dependence on control information.

[0003] The invention also relates to an on-board network for an electrically powered vehicle.

[0004] DE 10 2017 220 982 A1 discloses a traction network in an electric or hybrid vehicle. The traction network comprises a high-voltage battery connected to a pulse-controlled inverter via a positive high-voltage line and a negative high-voltage line. A Y capacitor is connected to each of the positive and negative high-voltage lines. A switching element is assigned to the Y capacitors, which can be controlled by a control unit depending on at least one operating state. DE 102021 003 180 A1 discloses an electrical on-board network for an electrically operated vehicle, comprising a first electrical potential line and a second electrical potential line, between which the electrical system is supplied with a direct current. The electrical system has two first interference suppression capacitors, which are electrically connected in series and are each electrically coupled to the potential lines via a terminal.The on-board network also has a switch.

[0005] In electrically powered vehicles, on-board electrical systems, particularly high-voltage on-board electrical systems, are typically designed as IT systems in which a first and second potential of a traction battery are isolated from a reference potential, in particular a vehicle housing potential. Power converters used in such on-board electrical systems and whose first and second lines can be connected to the first and second potential of the traction battery can generate high-frequency interference signals during operation, which must be filtered by means of a filter device for reasons of electromagnetic compatibility. Such a filter device typically has two capacitors, which serve in particular to divert a common-mode current on the first and second lines to a third line at the reference potential.

[0006] As the on-board electrical system voltage, which corresponds to the difference between the first potential and the second potential, increases, the amount of energy stored in the first and second capacitors of the filter device also increases with the square of the on-board electrical system voltage. Relevant standards, such as ISO 6469-3, limit this amount of energy to a predetermined value. This means that in the event of an insulation fault, particularly during charging of the traction battery, electrical charges stored in the capacitors and flowing away via the third line can be kept below a limit that is dangerous to the human body. When designing power converters, an energy budget predetermined by the design of the on-board electrical system must therefore be adhered to. The object of the invention is to provide an improved method for operating a power converter in the on-board electrical system of an electrically powered vehicle.

[0007] This object is achieved according to the invention in a power converter of the type mentioned at the outset in that the filter device has at least one resistance circuit with a first resistance component and with a second resistance component and the switching device is further configured to provide the first impedance and the second impedance each with a predetermined amount in the first filter mode by changing a connection of the resistance components within the filter device and to provide the first impedance and the second impedance each with a predetermined amount in the second filter mode which is higher than in the first filter mode.

[0008] The power converter according to the invention for an on-board power system of an electrically driven vehicle has a first line for a first potential, a second line for a second potential, and a third line for a reference potential. The power converter according to the invention further has a filter device. The filter device has a first terminal, a second terminal, and a third terminal. The first terminal is connected to the first line. The second terminal is connected to the second line. The third terminal is connected to the third line. The filter device further has a first capacitor and a second capacitor. The first capacitor is connected in a first current path from the first terminal to the third terminal.

[0009] The first capacitor influences a first impedance along the first current path to divert a common-mode current to the third terminal. The common-mode current is referenced to the first line and the second line. The second capacitor is connected in a second current path from the second terminal to the third terminal. The second capacitor influences a second impedance along the second current path to divert the common-mode current to the third terminal. The filter device further comprises at least one resistance circuit. The at least one resistance circuit comprises a first resistance component and a second resistance component. The filter device further comprises a switching device. The switching device is configured to switch between a first filter mode and a second filter mode depending on control information.The switching device is further configured to provide the first impedance and the second impedance, each with a predetermined value, by changing the interconnection of the resistance components within the filter device in the first filter mode. The switching device is further configured to provide the first impedance and the second impedance, each with a predetermined value that is higher than in the first filter mode, by changing the interconnection in the second filter mode.

[0010] In the power converter according to the invention, different impedances are specified along the current paths in the first and second filter modes. With regard to electrical safety, this advantageously allows the temporal progression of a body current in the event of an insulation fault to be more precisely limited, since the different impedances can modify the discharge time of the energy stored in the first and second capacitors toward the third terminal. This allows, in particular, a discharge time constant resulting from the body resistance and the respective impedances to be placed in a range with no or low risk of fibrillation.A further advantage of the power converter according to the invention is that the capacitances of the first capacitor and the second capacitor can also act as Y capacitances in the second filter mode and thus enable at least partial suppression of common-mode interference in the second filter mode as well.

[0011] The power converter according to the invention can be designed as an inverter, a DC-DC converter, or an active rectifier. The power converter according to the invention can further comprise a housing in which at least the first line, the second line, the third line, and the filter device are accommodated. The third line can be electrically conductively connected to the housing. The reference potential can therefore also be considered the housing potential.

[0012] Typically, the first potential differs from the second potential. Preferably, the first potential is greater than the second potential. The reference potential is preferably between the first potential and the second potential. The reference potential can also be understood as ground potential. In a preferred embodiment, the first line and the second line are each designed entirely or at least in sections as solid busbars. The first and the second line can be connected to a DC voltage connection, on which in particular a connection device for electrically contacting the power converter with a DC voltage source is formed. The filter device is preferably arranged on the DC voltage connection side.

[0013] The third line is not necessarily designed as a busbar. The third line can be a cable, a ground plane, or a fastening means by which the filter device is attached to the power converter, in particular to the housing.

[0014] In particular, a portion of the common-mode current flowing along the first line can be diverted via the first current path through the first impedance. In particular, a portion of the common-mode current flowing along the second line can be diverted via the second impedance through the second current path.

[0015] The first capacitor and the second capacitor can each have a first terminal and a second terminal, between which the capacitance of the capacitor is provided. The first terminal of the first capacitor can be connected to the first terminal of the filter device. The first terminal of the second capacitor can be connected to the second terminal of the filter device. The first capacitor and the second capacitor can each be formed by a capacitor component or a plurality of interconnected capacitor components.

[0016] A resistance circuit comprising a first resistance component and a second resistance component may be provided. A plurality of resistance circuits, each comprising a first resistance component and a second resistance component, may also be provided. The or a respective resistance circuit may have a first terminal and a second terminal. The first resistance component and the second resistance component may each have a first terminal and a second terminal, between which the ohmic resistance of the resistance component is provided.

[0017] The switching device is preferably a semiconductor switching device, which in particular has one or more transistor structures. Alternatively, it is also possible for the switching device to be an electromechanical switching device, which, for example, has one or more relays.

[0018] In a preferred embodiment, the filter device of the power converter according to the invention is configured to set a higher time constant for a low-pass filter formed by the capacitors and the at least one resistor circuit for filtering the common-mode current in the second filter mode along the first current path and the second current path than in the first filter mode. Thus, the fibrillation risk in the second filter mode can be specifically placed within a range that complies with the relevant standards.

[0019] Typically, the filter device of the power converter according to the invention has a center node located between the first capacitor and the second capacitor. Preferably, at least one resistance circuit is connected to the terminal of the first capacitor or the second capacitor facing the center node. In particular, the at least one resistance circuit is connected to the second terminal of the first capacitor or to the second terminal of the second capacitor. The terminal of the first capacitor facing the center node can be its second terminal. The terminal of the second capacitor facing the center node can be its second terminal.

[0020] With regard to the connection of the at least one resistance circuit within the filter device, the following preferred embodiments are available:

[0021] It can be provided that a resistance circuit is connected in a circuit branch between the center node and the third terminal. In this case, the first terminal of the resistance circuit is preferably connected to the third terminal, and the second terminal of the resistance circuit is connected to the center node.

[0022] Alternatively or additionally, a resistance circuit may be connected in series with the first capacitor in a circuit branch between the first terminal and the center node. The first terminal of the resistance circuit is connected, in particular, to the second terminal of the first capacitor. The second terminal of the resistance circuit is connected, in particular, to the center node.

[0023] Alternatively or additionally, a resistance circuit can be connected in series with the second capacitor in a circuit branch between the second terminal and the center node. The first terminal of the resistance circuit is connected, in particular, to the second terminal of the second capacitor. The second terminal of the resistance circuit is connected, in particular, to the center node. The at least one resistance circuit can thus comprise one resistance circuit, two resistance circuits, or three resistance circuits, which are connected as described above. The resistance circuits can also be configured differently.

[0024] In a preferred embodiment of the power converter according to the invention, the switching device for the or a respective resistance circuit comprises a switch. The switch can have a first terminal and a second terminal, as well as a switching path between the first terminal of the switch and the second terminal of the switch, which can be controlled as a function of the control information.

[0025] According to a first preferred embodiment, the switch forms a series circuit with the first resistance component, with the second resistance component being connected in parallel to the series circuit. Thus, depending on the switching state of the switch, the total resistance of the resistance circuit can correspond either to the resistance value of the second resistance component or to the inverse of the sum of the inverse values ​​of the resistance values ​​of the first and second resistance components.

[0026] It can be provided that the first terminal of the resistance circuit, the first terminal of the switch, and the first terminal of the second resistance component form a common circuit node. The second terminal of the switch can be connected to the first terminal of the first resistance component. The second terminal of the first resistance component, the second terminal of the second resistance component, and the second terminal of the resistance circuit can form a common circuit node.

[0027] According to a second preferred embodiment, the switch forms a parallel circuit with the second resistance component, with the first resistance component being connected in series with the parallel circuit. Thus, depending on the switching state of the switch, the total resistance of the resistance circuit can correspond either to the resistance value of the first resistance component or to the sum of the resistance values ​​of the first and second resistance components.

[0028] The first terminal of the first resistance component, the first terminal of the switch, and the first terminal of the resistance circuit can form a common circuit node. The second terminal of the first resistance component, the second terminal of the switch, and the first terminal of the second resistance component can form a common circuit node. The second terminal of the second resistance component can be connected to the second terminal of the resistance circuit.

[0029] Independently of the two previously described embodiments, the switching device can be configured to switch the switch to the conducting state to enter the first filter mode and / or to the blocking state to enter the second filter mode.

[0030] In the power converter according to the invention, it is further preferred if the resistance value of the first resistance component is smaller than the resistance value of the second resistance component. Thus, particularly in combination with the circuit design described above, a lower total resistance of the resistance circuit can be specified in the first filter mode than in the second filter mode.

[0031] In order to filter common-mode currents particularly efficiently in the first filter mode, the switching device can be designed as a bidirectionally conducting and / or blocking switch.

[0032] The capacitances of the first capacitor and the second capacitor can be equal. This enables a particularly symmetrical voltage distribution across the first and second capacitors. To also enable efficient suppression of differential-mode interference, the filter device can further comprise a third capacitor connected in parallel with the first capacitor and the second capacitor to the first terminal of the filter device and to the second terminal of the filter device. In other words, the third capacitor can provide a fixed X-capacitance.

[0033] In a preferred embodiment of the power converter according to the invention, the filter device comprises a circuit board. The first capacitor, the second capacitor, and the at least one resistor circuit can be arranged on the circuit board. The third capacitor can also be arranged on the circuit board. The first to third terminals of the filter device can be arranged on the circuit board. The switching device can be arranged on the circuit board.

[0034] The power converter according to the invention may further comprise an intermediate circuit capacitor connected between the first line and the second line.

[0035] The power converter according to the invention can further comprise a converter circuit connected between the first line and the second line. The converter circuit can comprise power semiconductor switches, which are connected in particular as a switching cell, power bridge, or B6 bridge circuit, in order to convert the voltage present between the first line and the second line in a switching mode. The filter device is preferably arranged on the side of the intermediate circuit capacitor facing away from the converter circuit.

[0036] The power converter according to the invention can further comprise inductive filter elements that act as series inductors in the first line and the second line and are arranged on the intermediate circuit capacitor side and / or the DC voltage input side, in particular spatially close to the filter device. The filter elements can be formed by ferrite cores, such as nanocrystalline cores, iron powder cores, or other cores made of magnetic material, around the lines.

[0037] Preferably, parasitic inductances along the first line and the second lines between the DC voltage connection on the one hand and the first connection and the second connection of the filter device or the DC voltage connection-side filter elements on the other hand are lower than between the first connection and the second connection of the filter device or the intermediate circuit capacitor-side filter elements on the one hand and the intermediate circuit capacitor on the other hand.

[0038] The object underlying the invention is further achieved by an on-board electrical system for an electrically driven vehicle, comprising at least one previously described power converter, a traction battery, a charging device which can be connected to an electrical network external to the vehicle for charging or discharging the traction battery, and a control device which is configured to provide the control information for adopting the second filter mode if and / or as long as the charging device is connected to the electrical network external to the vehicle.

[0039] Thus, the first filter mode can advantageously be specified in a ferry operation of the vehicle or the on-board network and the second filter mode can be specified in a charging operation.

[0040] The traction battery preferably has a nominal voltage of at least 400 volts, preferably at least 600 volts, particularly preferably at least 800 volts.

[0041] A power converter of the vehicle electrical system can be designed as an inverter which is designed to electrically supply an electrical machine, in particular a permanent or electrically excited synchronous machine, an axial flux motor or an asynchronous machine, with a multi-phase alternating voltage for driving the vehicle.

[0042] A power converter of the on-board electrical system can form part of the charging device and be designed to convert a direct or alternating voltage provided by the vehicle-external electrical network into a direct voltage for charging the traction battery.

[0043] A power converter of the vehicle electrical system can be designed as a DC-DC converter, which is configured to couple the vehicle electrical system to another vehicle electrical system, in particular a low-voltage vehicle electrical system. A potential of the low-voltage vehicle electrical system can correspond to the reference potential.

[0044] The vehicle electrical system may further comprise an electrical line, for example an electrically conductive fastening or a ground strap, by means of which the third line of the at least one power converter is electrically conductively connected to a body of the vehicle.

[0045] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. These are schematic representations and show:

[0046] Fig. 1 is a circuit diagram of a first embodiment of the power converter according to the invention;

[0047] Fig. 2 is a schematic diagram of the power converter according to the embodiment;

[0048] Fig. 3 is a circuit diagram of the filter device according to a second embodiment of the power converter according to the invention; Fig. 4 is a circuit diagram of the filter device according to a third embodiment of the power converter according to the invention; and

[0049] Fig. 5 is a block diagram of an embodiment of the on-board network according to the invention in a vehicle.

[0050] Fig. 1 is a circuit diagram of an embodiment of a power converter 1 .

[0051] The power converter 1 has a first line 2 for a first potential 3, a second line 4 for a second potential 5, and a third line 6 for a reference potential 7, which can also be considered ground potential. For example, the first potential 3 is higher than the second potential 5, and the power converter 1 is configured to operate with a potential difference of 800 volts between the first potential 3 and the second potential 5. The reference potential 7 is located, for example, between the first potential 3 and the second potential 5.

[0052] The power converter 1 further comprises a filter device 8. Specifically, the filter device 8 serves as an interference suppression filter, i.e., to improve the electromagnetic compatibility of the power converter 1, and is preferably arranged close to a DC voltage terminal 9.

[0053] The filter device 8 has a first terminal 10 connected to the first line 2, a second terminal 11 connected to the second line 4, and a third terminal 12 connected to the third line 6. In addition, the filter device 8 has a first capacitor 13 connected in a first current path 14 from the first terminal 10 to the third terminal 12 and influencing a first impedance along the first current path 14 to divert a common-mode current to the third terminal 12. The common-mode current is referenced to the first and second lines 2, 4. The filter device 8 also has a second capacitor 15 connected in a second current path 16 from the second terminal 11 to the third terminal 12 and influencing a second impedance along the second current path 16 to divert the common-mode current referenced to the first and second lines 2, 4 to the third terminal 12.In particular, a portion of the common-mode current flowing on the first line 2 can be diverted from the first terminal 10 to the third terminal 12 via the first current path 14. Correspondingly, a portion of the common-mode current flowing on the second line 4 can be diverted from the second terminal 11 to the third terminal 12 via the second current path 16. The current paths 14, 16 are illustrated purely schematically by dashed lines in Fig. 1. The capacitors 13, 15 each have a first terminal 13a, 15a and a second terminal 13b, 15b.

[0054] In addition, the filter device 8 has a first resistance circuit 17 and a second resistance circuit 18. The resistance circuits 17, 18 each have a first resistance component 19 and a second resistance component 20. The resistance circuits 17, 18 each have a first terminal 17a, 18a and a second terminal 17b, 18b. The resistance components 19, 20 each have a first terminal 19a, 20a and a second terminal 19b, 20b.

[0055] Furthermore, the filter device 8 has a switching device 21. The switching device 21 is configured to switch between a first filter mode and a second filter mode depending on control information 22. To this end, the switching device 21 changes the interconnection of the resistance components 19, 20 within the filter device such that, in the first filter mode, the first impedance and the second impedance are each provided with a predetermined value, and, in the second filter mode, the first impedance and the second impedance are each provided with a predetermined value that is higher than in the first filter mode.The filter device 8 is accordingly configured to set a higher time constant for a low-pass filter formed from the capacitors 13, 15 and the resistor circuits 17, 18 for filtering the common-mode current in the second filter mode along the first current path 14 and the second current path 16 than in the first filter mode. The filter device 8 has a center node 23 between the first capacitor 13 and the second capacitor. The first resistor circuit 17 is connected in series with the first capacitor 13 between the first terminal 10 and the center node 23. The second resistor circuit 18 is connected in series with the second capacitor 15 between the second terminal 11 and the center node 23. The first resistor circuit 17 is connected to the second terminal 13b of the first capacitor 13 facing the center node 23.The second resistance circuit 18 is connected to the second terminal 15b of the second capacitor 15 facing the center node.

[0056] In the present embodiment, the center node 23 is connected directly to the third terminal 12 of the filter device 8. The first current path 14 is routed from the first terminal 10 via the first capacitor 13, the first resistance circuit 17, and the center node 23 to the third terminal 12. The second current path is routed from the second terminal 11 via the second capacitor 15, the second resistance circuit 18, and the center node to the third terminal 12.

[0057] In detail, the first exemplary embodiment further provides that the first terminal 13a of the first capacitor 13 is connected to the first terminal 10 of the filter device 8. The first terminal 15a of the second capacitor 15 is connected to the second terminal 11 of the filter device 8. The first terminal 17a of the first resistance circuit 17 is connected to the second terminal 13b of the first capacitor 13. The second terminal 17b of the first resistance circuit 17 is connected to the center node 23. The first terminal 18a of the second resistance circuit 18 is connected to the second terminal 15b of the second capacitor 15. The second terminal 18b of the second resistance circuit 18 is connected to the center node 23. In addition, the switching device 21 has a first switch 24 for the first resistance circuit 17 and a second switch 25 for the second resistance circuit 18.The switches 24, 25 each have a first terminal 24a, 25a and a second terminal 24b, 25b, between which a switching path is formed that can be controlled depending on the control information 22. The switching device 21 is configured to switch the respective switch 24, 25 to the conducting state to enter the first filter mode and to the blocking state to enter the second filter mode.

[0058] In the present embodiment, each switch 24, 25 forms a series circuit with the first resistance component 19. The second resistance component 20 is connected in parallel to the series circuit of the switch 24, 25 and the first resistance component 19.

[0059] In detail, in the first resistance circuit 17, the first terminal 24a of the first switch 24, the first terminal 20a of the second resistance component 20, and the first terminal 17a of the first resistance circuit 17 form a common circuit node. The second terminal 24b of the first switch 24 is connected to the first terminal 19a of the first resistance component 19. The second terminal 19b of the first resistance component 19, the second terminal 20b of the second resistance component 20, and the second terminal 17b of the first resistance circuit 17 form a common circuit node.

[0060] Accordingly, in the second resistance circuit 18, the first terminal 25a of the second switch 25, the first terminal 20a of the second resistance component 20, and the first terminal 18a of the second resistance circuit 18 form a common circuit node. The second terminal 25b of the second switch 25 is connected to the first terminal 19a of the first resistance component 19. The second terminal 19b of the first resistance component 19, the second terminal 20b of the second resistance component 20, and the second terminal 18b of the second resistance circuit 18 form a common circuit node.

[0061] Optionally, a third capacitor 26 with a first terminal 26a and a second terminal 26b of the filter device 8 is provided. The third capacitor 26 is connected in parallel to the first capacitor 13 and the second capacitor 15, and in the present exemplary embodiment also to the resistor circuits 17, 18, to the first terminal 10 of the filter device 8 and to the second terminal 11 of the filter device 8. The first terminal 10 of the filter device 8, the first terminal 13a of the first capacitor 13, and the first terminal 26a of the third capacitor 26 form a common circuit node. Furthermore, the second terminal 11 of the filter device 8, the first terminal 15b of the second capacitor 15, and the second terminal 26b of the third capacitor 26 form a common circuit node. The third capacitor 26 provides a fixed X-capacitance.

[0062] With regard to the dimensioning of the components of the filter device 8, it is intended that the capacitance Ci of the first capacitor 13 is equal to the capacitance C2 of the second capacitor 15. The capacitance C3 of the third capacitor 26 is typically larger than the capacitances Ci, C2. The resistance value Ri of a respective first resistance component 19 is smaller than the resistance value R2 of a respective second resistance component 20.

[0063] Fig. 1 further shows an intermediate circuit capacitor 40, which is connected between the first line 2 and the second line 4, and a converter circuit 41, which is connected between the first line 2 and the second line 4. The filter device 8 is clearly arranged on the side of the intermediate circuit capacitor 40 facing away from the converter circuit 41. The power converter 1 further has four inductive filter elements 42, 43, 44, 45, which act as series inductors in the lines 2, 4 and are formed around the lines 2, 4, for example by ferrite cores, such as nanocrystalline cores, iron powder cores or other cores made of magnetic material. The filter elements 42 to 45 are arranged close to the filter device 8. The filter elements 42, 44 are arranged on the DC voltage input side with respect to the filter device 8. The filter elements 43, 45 are arranged on the intermediate circuit capacitor side with respect to the filter device 8.

[0064] In addition, parasitic inductances Li are shown schematically in Fig. 1 P , Lin along the first line 2 or the second line 4 between the DC voltage connection 9 and the filter device 8 or the filter elements 42, 44 as well as parasitic inductances L2 P , L2n along the first line 2 or the second line 4 between the filter device 8 or the filter elements 43, 45 and the intermediate circuit capacitor 40. The arrangement of the filter device 8 can be selected such that Li P and Lin less than L2 P and L2n to enable the most efficient filtering possible.

[0065] Fig. 2 is a schematic diagram of the power converter 1 according to the embodiment.

[0066] The filter device 8 has a printed circuit board 50 on which the terminals 10, 11, 12, the capacitors 13, 15, 26, the resistance circuits 18, 19, and the switching device 21 are arranged. The first line 2 and the second line 4 are each formed by solid busbars 51, 52, which are contacted with the terminals 10, 11 on the printed circuit board 50. The DC voltage terminal 9, designed as a connection device 53, is connected to a first end of the busbars 51, 52. The converter circuit 41 is connected to a second end of the busbars 51, 52. The intermediate circuit capacitor 40 is also contacted with the busbars 51, 52 and, based on the length of the busbars 51, 52, is located closer to the converter circuit 41 than to the filter device 8.The third terminal 12 of the filter device 8 is not connected to the busbars 51, 52, but is connected to a housing 55 of the power converter 1 by means of a fastening means 54, which forms the third line 6. The reference potential 7 can therefore also be considered the housing potential. The lines 2, 4 or the busbars 51, 52, the filter device 8, the intermediate circuit capacitor 40, and the converter circuit 41 are housed in the housing 55.

[0067] The power converter 1 can be designed as an inverter, a DC-DC converter, or an active rectifier. The converter circuit 41 comprises suitable semiconductor switching elements for this purpose.

[0068] Further exemplary embodiments of a power converter 1 are described below, to which – unless otherwise stated – the information on the first exemplary embodiment can be applied. Identical or equivalent components are provided with identical reference numerals.

[0069] Fig. 3 is a circuit diagram of the filter device 8 according to a second embodiment of a power converter 1.

[0070] In the second embodiment, the switches 24, 25 form a parallel circuit with the respective second resistance component 20. The respective first resistance component 19 is connected in series with this parallel circuit.

[0071] In detail, in the first resistance circuit 17, the first terminal 24a of the first switch 24, the first terminal 20a of the second resistance component 20, and the first terminal 17a of the first resistance circuit 17 form a common circuit node. The second terminal 24b of the first switch 24, the second terminal 20b of the second resistance component 20, and the first terminal 19a of the first resistance component 19 form a common circuit node. The second terminal 19b of the first resistance component 19 is connected to the second terminal 17b of the first resistance circuit 17.

[0072] Accordingly, in the second resistance circuit 18, the first terminal 25a of the second switch 25, the first terminal 20a of the second resistance component 20, and the first terminal 18a of the second resistance circuit 18 form a common circuit node. The second terminal 25b of the second switch 25, the second terminal 20b of the second resistance component 20, and the first terminal 19a of the first resistance component 19 form a common circuit node. The second terminal 19b of the first resistance component 19 is connected to the second terminal 18b of the second resistance circuit 18.

[0073] It should be mentioned again that - as in the first exemplary embodiment - the resistance value Ri of a respective first resistance component 19 is smaller than the resistance value R2 of a respective second resistance component 20 and the switching device 21 is designed to switch the respective switch 24, 25 to be conductive for adopting the first filter mode and to be blocking for adopting the second filter mode.

[0074] Fig. 4 is a circuit diagram of the filter device 8 according to a third embodiment of a power converter 1.

[0075] In the third exemplary embodiment, only one resistance circuit 27 and one switch 28 of the switching device 21 are provided. The resistance circuit 27 is connected in a circuit branch between the center node 23 and the third terminal 12 of the filter device 8. In detail, the first terminal 27a of the resistance circuit 27 is connected to the third terminal 12, and the second terminal 27b of the resistance circuit 27 is connected to the center node 23. In particular, the first current path 14 is led from the first terminal 10 via the first capacitor 13, the center node 23, and the resistance circuit 27 to the third terminal 12, and the second current path 16 is led from the second terminal 11 via the center node 23 and the resistance circuit 27 to the third terminal 12.

[0076] The resistance circuit 27 is configured analogously to one of the resistance circuits 17, 18 according to the first exemplary embodiment. This means that in the present third exemplary embodiment, the switch 28 forms a series circuit with the first resistance component 19, and the second resistance component 20 is connected in parallel to the series circuit of the switch 28 and the first resistance component 19.

[0077] In detail, in the resistance circuit 27, the first terminal 28a of the switch 28, the first terminal 20a of the second resistance component 20, and the first terminal 27a of the resistance circuit 27 form a common circuit node. The second terminal 28b of the switch 28 is connected to the first terminal 19a of the first resistance component 19. The second terminal 19b of the first resistance component 19, the second terminal 20b of the second resistance component 20, and the second terminal 27b of the resistance circuit 27 form a common circuit node.

[0078] In the third embodiment, the second terminals 13b, 15b of the capacitors 13, 15 are connected to the center node 23 or, together with the second terminal 27b of the resistor circuit 27, form the center node 23. The first terminal 13a of the first capacitor 13 is connected to the first terminal 10 of the filter device 8. The first terminal 15a of the second capacitor 15 is connected to the second terminal 11 of the filter device 8.

[0079] It also applies to the third exemplary embodiment that the resistance value Ri of the first resistance component 19 is smaller than the resistance value R2 of the second resistance component 20 and the switching device 21 is configured to switch the switch 27 to the conducting state for adopting the first filter mode and to the blocking state for adopting the second filter mode.

[0080] In the third embodiment, the third capacitor 26 is connected in parallel to the first and second capacitors 13, 15.

[0081] According to Fig. 2, in the third embodiment, the resistance circuit 27 is arranged on the circuit board 50.

[0082] According to a fourth embodiment, which otherwise corresponds to the third embodiment, the resistance circuit 27 is configured in accordance with the resistance circuit 17 according to the second embodiment. This means that the switch 28 forms a parallel circuit with the second resistance component 20, and the first resistance component 19 is connected in series with this parallel circuit.

[0083] According to further embodiments corresponding to the first or second embodiment, a third resistance circuit 27 according to the third or fourth embodiment is additionally provided.

[0084] According to further embodiments corresponding to one of the preceding embodiments, a resistance circuit 17, 18 according to the first embodiment between one of the capacitors 13, 15 and the center node 23 can also be combined with a resistance circuit 17, 18 according to the second embodiment between the other of the capacitors 13, 15 and the center node.

[0085] Fig. 5 is a block diagram of an exemplary embodiment of an on-board electrical system 101 in a vehicle 100. The on-board electrical system 101 comprises a traction battery 102 with a nominal voltage of, for example, 800 volts, a charging device 103 that can be connected to an external electrical network 104 for charging or discharging the traction battery 102, and a control device 105 configured to provide the control information 22. The on-board electrical system 101 can be considered a high-voltage electrical system because its operating voltage is regularly above 60 V.

[0086] The vehicle electrical system 101 includes a power converter 1 according to one of the previously described exemplary embodiments, which is designed as an inverter. The power converter 1 is configured to electrically supply an electric machine 106 of the vehicle electrical system 101 with a multiphase alternating voltage for driving the vehicle 100. The electric machine 106 is, for example, a permanently or electrically excited synchronous machine, an axial flux machine, or an asynchronous machine.

[0087] The vehicle electrical system 101 has a further power converter 1a according to one of the previously described embodiments, which is designed as an active rectifier or as a DC-DC converter and forms part of the charging device 103. The power converter 1a is configured to convert a DC or AC voltage provided by the vehicle-external electrical network 104 into a DC voltage for charging the traction battery 102.

[0088] The vehicle electrical system 101 has a further power converter 1b according to one of the previously described embodiments, which is designed as a DC-DC converter. The power converter 1b is configured to couple the vehicle electrical system 101 to a further vehicle electrical system 107 of the vehicle 100. The further vehicle electrical system 107 is, for example, a low-voltage vehicle electrical system with an operating voltage of less than 60 volts, for example, 12 volts, 24 volts, or 48 volts.

[0089] The control device 105 communicates with the charging device 103 via a signal line symbolized by a double arrow. The control device 105 is configured to provide the power converters 1, 1a, 1b with the control information 22 for adopting the second filter mode when and as long as the charging device 103 is connected to the vehicle-external electrical network 104. The second filter mode can therefore be understood in particular as a charging mode. The control information 22, on the other hand, is provided in particular for adopting the first filter mode when the charging device 103 is disconnected from the vehicle-external electrical network 104 and when the vehicle 100 is moving. The first filter mode can therefore also be understood as a driving mode. The on-board electrical system 101 can further comprise electrical conductors by means of which the third line 6 (see Fig.1) of a respective power converter 1, 1a, 1b is electrically connected to a body 108 of the vehicle 101, so that the reference potential 7 can also be considered a body potential. This is simultaneously one of the potentials of the further vehicle electrical system 107.

[0090] The vehicle 100 can accordingly be designed as a battery electric vehicle (BEV) or as a hybrid vehicle.

Claims

Patent claims 1 . Power converter (1, 1 a, 1 b) for an on-board network (101) of an electrically driven vehicle (100), comprising a first line (2) for a first potential (3), a second line (4) for a second potential (5), a third line (6) for a reference potential (7) and a filter device (8), which - a first terminal (10) connected to the first line (2), - a second terminal (11) connected to the second line (4), - a third terminal (12) connected to the third line (6), - a first capacitor (13) connected in a first current path (14) from the first terminal (10) to the third terminal (12) and influencing a first impedance along the first current path (14) to divert a common-mode current related to the first and second lines (4, 5) to the third terminal (12), - a second capacitor (15) connected in a second current path (16) from the second terminal (11) to the third terminal (12) and influencing a second impedance along the second current path (16) for diverting the common-mode current to the third terminal (12), and - a switching device (21) which is designed to switch between a first filter mode and a second filter mode as a function of control information (22), characterized in that the filter device (8) has at least one resistance circuit (17, 18, 27) with a first resistance component (19) and with a second resistance component (20) and the switching device (21) is further designed to change a connection of the resistance components (19, 20) within the filter device (8) - in the first filter mode, to provide the first impedance and the second impedance each with a predetermined amount and in the second filter mode, the first impedance and the second impedance are each provided with a predetermined amount that is higher than in the first filter mode.

2. Power converter according to claim 1, wherein the filter device (8) is configured to set a higher time constant of a low-pass filter formed from the capacitors (13, 15) and the at least one resistance circuit (17, 18, 27) for filtering the common-mode current in the second filter mode along the first current path (14) and the second current path (16) than in the first filter mode.

3. Power converter according to claim 1 or 2, wherein the filter device (8) has a center node (23) located between the first capacitor (13) and the second capacitor (15).

4. Power converter according to claim 3, wherein a resistance circuit (27) is connected in a circuit branch between the center node (23) and the third terminal (12).

5. Power converter according to claim 3 or 4, wherein - a resistance circuit (17) is connected in series with the first capacitor (13) in a circuit branch between the first terminal (10) and the center node (23) and / or - a resistance circuit (18) is connected in series with the second capacitor (15) in a circuit branch between the second terminal (11) and the center node (23).

6. Power converter according to one of claims 3 to 5, wherein the at least one resistance circuit (17, 18, 27) is connected to the terminal (13b, 15b) of the first capacitor (13) or the second capacitor (15b) facing the center node (23).

7. Power converter according to one of the preceding claims, wherein the switching device (21) for the or a respective resistance circuit has a switch (24, 25, 28).

8. Power converter according to claim 7, wherein the switch (24, 25, 28) forms a series circuit with the first resistance component (19), and the second resistance component (20) is connected in parallel to the series circuit.

9. Power converter according to claim 7, wherein the switch (24, 25) forms a parallel circuit with the second resistance component (20), and the first resistance component (19) is connected in series to the parallel circuit.

10. Power converter according to one of claims 7 to 9, wherein the switching device (21) is configured to switch the switch (24, 25, 28) to conduct in order to adopt the first filter mode and / or to switch it to block in order to adopt the second filter mode. 11 . Power converter according to one of the preceding claims, wherein the resistance value of the first resistance component (19) is smaller than the resistance value of the second resistance component (20).

12. Power converter according to one of the preceding claims, wherein the filter device (21) further comprises a third capacitor (26) which is connected in parallel to the first and second capacitors (13, 15) to the first terminal (10) and to the second terminal (11).

13. Power converter according to one of the preceding claims, wherein the filter device (8) comprises a printed circuit board (50), wherein - the first capacitor (13), the second capacitor (14) and the at least one resistance circuit (17, 18, 27) are arranged on the printed circuit board (50) and / or - the first to third terminals (10, 11, 12) of the filter device (8) are arranged on the printed circuit board (50) and / or - the switching device (21) is arranged on the printed circuit board (50).

14. Power converter according to one of the preceding claims, further comprising an intermediate circuit capacitor (40) which is connected between the first line (2) and the second line (4), and a converter circuit (41) which is connected between the first line (2) and the second line (4), wherein the filter device (8) is arranged on the side of the intermediate circuit capacitor (40) facing away from the converter circuit (41).

15. On-board electrical system (101) for an electrically driven vehicle (100), comprising at least one power converter (1, 1a, 1b) according to one of the preceding claims, a traction battery (102), a charging device (103) which can be connected to an electrical network (104) external to the vehicle for charging or discharging the traction battery (102), and a control device (105) which is designed to provide the control information (22) for adopting the second filter mode if and / or as long as the charging device (103) is connected to the electrical network (104) external to the vehicle.

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