Vehicle having an electric circuit device and two electric drive units, and method for operating this vehicle

Abstract

The present invention relates to a vehicle (1) having an electrical circuit device (2), the electrical circuit device (2) comprising: a traction battery (4); an electrical connection part (5) for electrical connection with an electrical unit (3) outside the vehicle; a first high voltage potential (P1); a second high voltage potential (P2), wherein the first high voltage potential (P1) is a positive high voltage potential and the second high voltage potential (P2) is a negative high voltage potential, or vice versa. At this time, the circuit device (2) has two electric drive units (A1, A2) each having an inverter (I1, I2) and a three-phase electric machine (M1, M2) electrically connected thereto for driving the vehicle (1); the two electric drive units (A1, A2) can be electrically connected in series between the electrical connection part (5) and the traction battery (4), so that the first electric drive unit (A1) draws up the first high voltage potential (P1) from the electrical connection part (5) to the traction battery (4), and the second electric drive unit (A2) draws up the second high voltage potential (P2). According to the present invention, the inverters (I1, I2) each have a capacitor (C1, C2) between the potential line (PL1) of the first high voltage potential (P1) and the potential line (PL2) of the second high voltage potential (P2); the circuit device (2) is configured such that the second electric drive unit (A2) can be electrically connected in series with the capacitor connection part of the first electric drive unit (A1).

Description

Technical Field

[0001] The present invention relates to a vehicle having the features of the preamble of claim 1 and to a method for operating such a vehicle.

Background Art

[0002] Patent Document 1 describes an electric drive system for a vehicle, which includes a battery having two different electrochemical partial regions and two inverters that can be electrically connected to or are connected to one partial region of the battery each. For this purpose, the electric drive system includes two three-phase electric machines that can be electrically connected to or are connected to one of the inverters each, and the neutral points of the three-phase electric machines can be electrically connected to or are connected to one charging contact of the DC charging connection of the electric drive system each.

[0003] From Patent Document 2, a system for charging an electrical energy storage device by an electric drive system is known. For electrical insulation between a voltage source and the energy storage device to be charged, an inductive connection between the phase windings or phase strands of the electric machine is intended. For this purpose, the phase windings of the electric machine may be subdivided into two groups, each group having a separate neutral point. For each neutral point, a separate bridge circuit consisting of a capacitor and a diode or semiconductor switch is provided.

[0004] Patent Document 3 also relates to an electric drive system for a vehicle, which includes a three-phase electric machine, an electrical energy storage device, an inverter of the three-phase electric machine, and a charging connection portion for connecting the electrical energy storage device to a charging unit. At this time, the switching device has a first switching state in which the charging connection portion is electrically connected to the electrical energy storage device and the inverter is electrically insulated from the charging connection portion and the electrical energy storage device. In the second switching state of the switching device, the charging connection portion is electrically connected to the inverter and the electrical energy storage device. In the third switching state of the switching device, the inverter is electrically connected to the electrical energy storage device and the charging connection portion is electrically insulated from the electrical energy storage device and the inverter.

[0005] Furthermore, in the prior art, as described in Patent Document 4, an energy connector for electrically connecting an in-vehicle electrical system and a method for electrically connecting an in-vehicle electrical system are known. The energy connector for electrically connecting a first in-vehicle electrical system to which a first DC voltage is applied and a second in-vehicle electrical system to which a second DC voltage is applied has first and second time-controlled energy converters each having an in-vehicle electrical system connection portion and an intermediate circuit connection portion. The in-vehicle electrical system connection portion of the first time-controlled energy converter is connected to the first in-vehicle electrical system, and the second clock-type energy converter is connected to the second in-vehicle electrical system. The intermediate circuit connection portions of the first and second time-controlled energy converters are connected to a common DC voltage intermediate circuit. The first potential of the DC voltage intermediate circuit is electrically connected to one of the potentials of the first in-vehicle electrical system by the first time-controlled energy converter. The second potential of the DC voltage intermediate circuit is electrically connected to one of the potentials of the second in-vehicle electrical system by the second time-controlled energy converter.

[0006] Patent Document 5 describes a circuit device for a hybrid vehicle or an electric vehicle. This circuit device includes a high-voltage battery for storing electrical energy, at least one electric machine for driving the hybrid vehicle or the electric vehicle, a power conversion device capable of converting the high-voltage DC voltage provided by the high-voltage battery into a high-voltage AC voltage for the operation of the electric machine, and a charging connection for providing electrical energy for charging the high-voltage battery. The power conversion device is configured as a three-stage power conversion device.

[0007] From Patent Document 6, a circuit device for a hybrid vehicle or an electric vehicle is known. This circuit device includes a high-voltage battery for storing electrical energy, at least one electric machine for driving the hybrid vehicle or the electric vehicle, a power conversion device capable of converting the high-voltage DC voltage provided by the high-voltage battery into a high-voltage AC voltage for the operation of the electric machine, and a charging connection for providing electrical energy for charging the high-voltage battery. The power conversion device is configured as a three-stage power conversion device and has at least one switch unit assigned to one phase of the electric machine, each including two series-connected switch groups each having two IGBTs connected in series. A connection directly electrically connected to the line of the charging connection is arranged between the IGBTs of each switch group.

[0008] Patent Document 7 describes an in-vehicle electrical system for an electrically drivable vehicle. This in-vehicle electrical system includes a vehicle battery, a polyphase electrical machine, and an inverter electrically connected to the vehicle battery, which includes respective series circuits each consisting of a switching unit connected in series for each phase of the electrical machine. The switching unit of each series circuit provides a respective center connection portion to which each phase winding of the electrical machine is connected. The inverter is configured as a three-level inverter in which each switching unit has a series circuit consisting of two switching members connected to each other at a connection point. In at least one of these series circuits, at each connection point, one inductance is connected to each first connection portion. Each second connection portion of the inductance can be electrically connected to the DC voltage charging connection portion of the vehicle.

[0009] Patent Document 8 describes an electric drive system for a vehicle and a method of operating the same. The electric drive system includes at least one three-phase electrical machine and a battery for supplying electrical energy to the three-phase electrical machine. The three-phase electrical machine can be electrically connected to or is connected to the battery via an inverter. The neutral point of the three-phase electrical machine can be electrically connected to or is connected to the positive pole connection portion of the DC charging connection portion of the electric drive system, and the negative pole of the battery can be electrically connected to or is connected to the negative pole connection portion of the DC charging connection portion of the electric drive system.

[0010] Patent Document 9 describes a charging device for charging a vehicle battery having a buck converter. This charging device includes an electrical machine for driving the vehicle and a traction inverter that converts the DC voltage of the battery during the driving operation of the vehicle for the electrical machine. The electrical machine, together with the traction inverter, serves as a boost converter for the charging operation of the battery. A buck converter is pre-connected to the boost converter to reduce the input DC voltage to an appropriate charging voltage for the battery after boosting by the boost converter.

[0011] From Patent Document 10, an in-vehicle electrical system having an inverter and a DC-DC converter having an energy storage member in a negative path is known. An in-vehicle electrical system for an automobile that can be partially or fully electrically driven can generate an AC voltage from a DC voltage for a first operating state of the automobile and can generate a DC voltage from an AC voltage for a second operating state of the automobile. It includes an electrical inverter and at least one galvanically coupled DC-DC converter that can be wired to the electrical inverter on the DC voltage side of the electrical inverter. At least one DC-DC converter has a time-controlled energy storage member wired to the negative path of the at least one DC-DC converter.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Summary of the Invention

Problems to be Solved by the Invention

[0013] The problem of the present invention is to provide a vehicle improved compared to the prior art and a method for operating this vehicle improved compared to the prior art.

Means for Solving the Problems

[0014] According to the present invention, this problem is solved by a vehicle having the features of claim 1 and a method for operating this vehicle having the features of claim 6. Advantageous embodiments of the present invention are the subject of the dependent claims.

[0015] The vehicle has an electric circuit device. This circuit device includes an electrical connection for the electrical connection between the traction battery and an electrical unit outside the vehicle, a first high voltage potential, and a second high voltage potential. The first high voltage potential is a positive high voltage potential, the second high voltage potential is a negative high voltage potential, or vice versa. The term "high voltage", also abbreviated as HV, particularly means an electrical DC voltage greater than about 60V. In particular, the term "high voltage" must be interpreted in accordance with the standard ECE R 100.

[0016] According to the present invention, the circuit device includes two electric drive units each having an inverter and a three-phase electrical machine electrically connected thereto for driving the vehicle. The traction battery is provided, in particular, for supplying electrical energy to these drive units in order to drive the vehicle.

[0017] According to the present invention, an electric circuit device is configured such that two electric drive units can be electrically connected in series between an electrical connection and a traction battery, whereby a first electric drive unit raises a first high voltage potential from the electrical connection to the traction battery and a second electric drive unit raises a second high voltage potential. Correspondingly, in the opposite direction, i.e., from the traction battery to the electrical connection, the first electric drive unit lowers the first high voltage potential and the second electric drive unit lowers the second high voltage potential. Thus, the solution according to the present invention provides a DC-DC converter formed by two electric drive units, i.e., formed by the above-described wiring, and operating in the above-described manner, between the electrical connection and the traction battery. Here, the terms "raise" and "lower" represent the absolute value of the respective potential voltage with respect to a reference potential, in particular with respect to the ground potential, i.e., without considering the positive or negative sign.

[0018] Thus, the solution according to the present invention utilizes the electric drive unit that already exists in the vehicle as a DC-DC converter, and in so doing, makes it possible to provide it for additional purposes of use. Thereby, in particular, it becomes possible to charge the traction battery by an electric unit outside the vehicle configured as a DC charging station that is electrically connected to the electrical connection section and has a charging voltage lower than the rated voltage of the traction battery. Furthermore, energy supply in the opposite direction, also called a step-down operation, is likewise possible. At this time, electrical energy is provided by the traction battery to an electric unit outside the vehicle that is electrically connected to the electrical connection section, which is for supplying the electrical energy of the traction battery to, for example, the public energy supply network via a DC charging station electrically connected to the electrical connection section, or to the energy supply network of a building. Such energy supply in both directions is also called bi-directional charging. According to the solution of the present invention, it is not necessary to provide an additional DC-DC converter in the vehicle for this purpose, whereby a corresponding reduction in design space, weight, and cost is realized. According to the solution of the present invention, there is also no longer a need for other solutions for enabling the charging of the traction battery at a relatively low charging voltage, for example, there is no longer a need to configure the traction battery as a switching battery for enabling charging by a modified circuit of the battery modules of the traction battery.

[0019] In the method of the present invention for operating a vehicle, correspondingly, for charging the traction battery by an electric unit outside the vehicle configured as a DC charging station that is electrically connected to the electrical connection section and has a charging voltage lower than the rated voltage of the traction battery, and / or for providing electrical energy from the traction battery to an external unit of the vehicle that is electrically connected to the electrical connection section, it is intended that two electric drive units be electrically switched in series between the electrical connection section and the traction battery.

[0020] According to the solution of the present invention, it becomes possible to charge an 800V traction battery, for example, at a DC charging station having a charging voltage of 400V or 500V.

[0021] Furthermore, the solution of the present invention enables fulfillment of safety requirements related to overload of the insulation part of the DC charging station, a function without constraints of the insulation monitor, and interruption of a short circuit of the traction battery caused and generated in the vehicle due to insulation failure.

[0022] According to the present invention, the inverter has capacitors respectively between the potential lines of the first high voltage potential and the potential lines of the second high voltage potential. At this time, the circuit device is configured to be able to connect the second electric drive unit in series with the capacitor connection part of the first electric drive unit.

[0023] In one possible embodiment, one of the potential lines of the inverter of the second electric drive unit is intended to be electrically connected to a capacitor connection contact of the capacitor connection of the inverter of the first electric drive unit, which has the same high-voltage potential. In that case, in order to enable the electrical series circuit described above for the two drive units, for example, the circuit device is such that the neutral point of the three-phase electric machine of the second electric drive unit can be electrically connected to another capacitor connection contact of the capacitor connection of the inverter of the first electric drive unit, and the potential line of the inverter that is electrically connected to the capacitor connection contact can be electrically connected to a connection contact of an electrical connection part having the same high-voltage potential, and the neutral point of the first three-phase electric machine is intended to be configured to be electrically connectable to another connection contact of the electrical connection part. As an alternative, in order to enable the electrical series circuit of the two drive units described above, for example, the circuit device is such that the winding connection part of the three-phase electric machine of the second electric drive unit can be electrically connected to another capacitor connection contact of the capacitor connection of the inverter of the first electric drive unit, and the potential line of the inverter that is electrically connected to the capacitor connection contact can be electrically connected to a connection contact of an electrical connection part having the same high-voltage potential, and the winding connection part of the three-phase electric machine of the first electric drive unit is intended to be configured to be electrically connectable to another connection contact of the electrical connection part.

[0024] In particular, the traction battery is intended to be electrically connected to the capacitor connection of the second electric drive unit. Furthermore, in particular, in order to further enable the basic function of the electric drive unit, that is, to drive the vehicle, it is preferably intended that the circuit device be configured such that the traction battery can be electrically connected to the capacitor connection of the first electric drive unit. Thereby, electrical energy can be supplied to the two electric drive units by the traction battery. Therefore, in the method of operating the vehicle, it is intended that both inverters be directly connected to the traction battery respectively for the running operation of the vehicle.

[0025] In one possible embodiment of the vehicle, the circuit device is intended to be configured such that the electrical connection can be directly electrically connected to the traction battery. Thereby, it is also possible to charge the traction battery by an external electrical unit of the vehicle configured as a DC charging station that is electrically connected to the electrical connection and has a charging voltage that is at least as large as the rated voltage of the traction battery. In a method of operating the vehicle accordingly, the electrical connection is intended to be directly connected to the traction battery for charging the traction battery by an external electrical unit of the vehicle configured as a DC charging station that is electrically connected to the electrical connection and has a charging voltage that is at least as large as the rated voltage of the traction battery.

[0026] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

DETAILED DESCRIPTION OF THE INVENTION

[0028] In any of the figures, corresponding parts are denoted by the same reference numerals.

[0029] FIGS. 1 and 6 show, by way of example, two embodiments of the vehicle 1 having the electric circuit device 2. Here, the vehicle 1 is electrically connected to an external electric unit 3 of the vehicle configured as a DC charging station in both of the illustrated embodiments. Here, the internal resistance Rg of the DC charging station is also shown respectively.

[0030] The circuit device 2 includes a traction battery 4. Here, the internal resistance Rb of the traction battery 4 is also shown respectively. Further, it includes an electrical connection portion 5 for electrical connection to the external electric unit 3 of the vehicle, and a first high voltage potential P1 and a second high voltage potential P2. In the illustrated embodiment, the first high voltage potential P1 is a positive high voltage potential, and the second high voltage potential P2 is a negative high voltage potential. In another embodiment, this may be reversed.

[0031] Furthermore, the circuit device 2 includes two electric drive units A1, A2 each having an inverter I1, I2 and a three-phase electric machine M1, M2 electrically connected thereto for driving the vehicle 1.

[0032] In both embodiments, the circuit device 2 is configured such that both electric drive units A1, A2 can be electrically connected in series between the electric connection part 5 and the traction battery 4, so that the first electric drive unit A1 raises the first high voltage potential P1 from the electric connection part 5 to the traction battery 4, and the second electric drive unit A2 raises the second high voltage potential P2, or vice versa, pulls it down. By such a solution, a DC-DC converter is formed by the drive units A1, A2 wired in such a manner, which enables so-called bidirectional charging, that is, in one direction, the traction battery 4 is charged by an external electric unit 3 of the vehicle configured as a DC charging station electrically connected to the electric connection part 5 with a charging voltage lower than the rated voltage of the traction battery 4, and in the other direction, the traction battery 4 provides electrical energy to the external electric unit 3 of the vehicle electrically connected to the electric connection part 5.

[0033] The inverters I1, I2 each have an inverter circuit IS1, IS2 including, in particular as shown here, a plurality of inverter circuit units IE1 to IE12, in particular semiconductor switching units, in particular transistors, in particular bipolar transistors having insulated gate electrodes, each in particular in combination with a diode configured as a freewheeling body diode. The inverter circuits IS1, IS2 are arranged, in particular, between the potential line PL1 of the first high voltage potential P1 and the potential line PL2 of the second high voltage potential P2 of the respective inverters I1, I2. The three-phase machines M1, M2 of the respective drive units A1, A2 have three motor windings U1, V1, W1, U2, V2, W2 connected to the inverters I1, I2 of the drive units A1, A2 in a star connection in the manner shown.

[0034] Furthermore, inverters I1 and I2 each have capacitors C1 and C2 between two potential lines PL1 and PL2. Due to the electrical series circuit of the two drive units A1 and A2 described above, the circuit device 2 is configured such that the second electrical drive unit A2 can be electrically connected in series with the capacitor connection of the first electrical drive unit A1. For this purpose, one of the potential lines of the inverter I2 of the second electrical drive unit A2 (in this example, the first potential line PL1) is electrically connected to the capacitor connection contact of the capacitor connection of the inverter I1 of the first drive unit A1, which has the same high voltage potential (in this example, the first high voltage potential P1).

[0035] Furthermore, in the first embodiment shown in FIG. 1, the circuit device 2 is such that the neutral point SP2 of the three-phase electrical machine M2 of the second electrical drive unit A2 can be electrically connected to the other capacitor connection contact of the capacitor connection of the inverter I1 of the first electrical drive unit A1 when the first switch S1 is closed in this example, and the potential line PL2 of the inverter I1 electrically connected to the capacitor connection contact can be electrically connected to the connection contact of the electrical connection part 5 having the same high voltage potential P2 when the second switch S2 is closed in this example, and the neutral point SP1 of the three-phase electrical machine M1 of the first electrical drive unit A1 can be electrically connected to the other connection contact of the electrical connection part 5 when the third switch S3 is closed in this example.

[0036] In another embodiment shown in FIG. 6, as an alternative, the winding connection part of the three-phase electrical machine M2 of the second electrical drive unit A2 can be electrically connected to the other capacitor connection contact of the inverter I1 of the first electrical drive unit A1 when the first switch S1 is closed in this example, and the potential line PL2 of the inverter I1 electrically connected to the capacitor connection contact can be electrically connected to the connection contact of the electrical connection part 5 having the same high voltage potential P2 when the second switch S2 is closed in this example, and the winding connection part of the three-phase electrical machine M1 of the first electrical drive unit A1 can be electrically connected to the other connection contact of the electrical connection part 5 when the third switch S3 is closed in this example.

[0037] Furthermore, in both embodiments, the traction battery 4 is intended to be electrically connected to the capacitor connection of the second electric drive unit A2. Thereby, on the one hand, the traction battery 4 can be charged as described above, and on the other hand, the running operation of the vehicle 1 becomes possible. To execute the running operation, the circuit device 2 is further intended to be configured such that, in this example by closing the fourth switch S4, the traction battery 4 can be electrically connected to the capacitor connection of the first electric drive unit A1. By this switch, in the illustrated embodiment, the second potential line PL2 of the inverter I1 of the first electric drive unit A1 is connected to the second high voltage potential P2 of the traction battery 4.

[0038] Furthermore, the circuit device 2 enables the traction battery 4 to be charged by an external electric unit 3 of the vehicle configured as a DC charging station that is electrically connected to the electrical connection part 5, where the charging voltage is at least as large as the rated voltage of the traction battery 4. For this purpose, the circuit device 2 is configured such that in both embodiments, by closing the fifth and sixth switches S5, S6, the electrical connection part 5 can be directly electrically connected to the traction battery 4, whereby the high voltage potentials P1, P2 of the traction battery 4 and the external electric unit 3 of the vehicle are directly connected to each other by the corresponding direct potential lines PL1, PL2.

[0039] The switches S1 to S6 are each configured as contactors, for example.

[0040] In the two embodiments shown in FIGS. 1 and 6, an EMC output filter (EMC = electromagnetic compatibility), not shown here, may additionally be provided from the vehicle 1 to the DC charging station.

[0041] For charging the traction battery 4 by an external electric unit 3 of the vehicle configured as a DC charging station electrically connected to the electrical connection part 5 when the charging voltage is lower than the rated voltage of the traction battery 4, and / or for providing electrical energy from the traction battery 4 to the external electric unit 3 of the vehicle electrically connected to the electrical connection part 5, two electric drive units A1, A2 are electrically connected in series between the electrical connection part 5 and the traction battery 4. For this purpose, in the embodiments shown in FIGS. 1 and 6, switches S1, S2 and S3 are closed and switches S4, S5 and S6 are opened.

[0042] For charging the traction battery 4 by an external electric unit 3 of the vehicle configured as a DC charging station electrically connected to the electrical connection part 5 when the charging voltage is at least as large as the rated voltage of the traction battery 4, the electrical connection part 5 is intended to be directly connected to the traction battery 4. For this purpose, in the embodiments shown in FIGS. 1 and 6, switches S5 and S6 are closed. At this time, the switching positions of the other switches S1 to S4 are not important, that is, they may be open or closed respectively.

[0043] For the running operation of the vehicle 1, both inverters I1, I2 are directly connected to the traction battery 4 respectively. For this purpose, in the embodiments illustrated in FIGS. 1 and 6, switch S4 is closed and the other switches S1, S2, S3, S5, S6 are opened.

[0044] FIGS. 2 and 7 show, for each of the embodiments of FIGS. 1 to 6, the increase in current AB1 in the motor windings U1, V1, W1 of the first drive unit A1 by a solid arrow and the increase in current AB2 in the motor windings U2, V2, W2 of the second drive unit A2 by a dashed arrow for the charging of the traction battery 4 by an external electric unit 3 of the vehicle configured as a DC charging station electrically connected to the electrical connection part 5 when the charging voltage is lower than the rated voltage of the traction battery 4.

[0045] Figures 3 and 8 show, for each of the embodiments of FIGS. 1 to 6, the freewheeling FL1 of the current in the motor windings U1, V1, W1 of the first drive unit A1, indicated by solid arrows, for charging the traction battery 4 by an external electric unit 3 of the vehicle configured as a DC charging station electrically connected to the electrical connection portion 5, with the charging voltage being lower than the rated voltage of the traction battery 4, and the freewheeling FL2 of the current in the motor windings U2, V2, W2 of the second drive unit A2, indicated by dashed arrows.

[0046] Figures 4 and 9 show, for each of the embodiments of FIGS. 1 to 6, the increase AB1 of the current in the motor windings U1, V1, W1 of the first drive unit A1, indicated by solid arrows, for providing electrical energy from the traction battery 4 to an external electric unit 3 of the vehicle electrically connected to the electrical connection portion 5, and the increase AB2 of the current in the motor windings U2, V2, W2 of the second drive unit A2, indicated by dashed arrows.

[0047] Figures 5 and 10 show, for each of the embodiments of FIGS. 1 to 6, the freewheeling FL1 of the current in the motor windings U1, V1, W1 of the first drive unit A1, indicated by solid arrows, for providing electrical energy from the traction battery 4 to an external electric unit 3 of the vehicle electrically connected to the electrical connection portion 5, and the freewheeling FL2 of the current in the motor windings U2, V2, W2 of the second drive unit A2, indicated by dashed arrows.

[0048] Furthermore, the above-described solution avoids the drawbacks of galvanically coupled DC-DC converters. This is because such DC-DC converters cause a potential shift only at one of the high voltage potentials P1, P2, while the other high voltage potentials P2, P1 are directly connected from the DC charging station to the vehicle 1. This can lead to an overload of the insulation during the charging process. The cause can be an asymmetric insulation resistance distribution in the DC charging station and / or the vehicle 1. Furthermore, the insulation monitor also leads to a potential shift that can lead to an insulation overload at the DC charging station.

[0049] In contrast, with the solution described here, as illustrated in FIGS. 11 to 13, the potential shifts of both potentials P1, P2 can be controlled. Here, the charging of a traction battery 4 with a rated voltage of 800V at a DC charging station with a charging voltage of 400V is shown respectively. Two potentials P1, P2 from the left DC charging station to the right traction battery 4 and a reference potential M having 0V, particularly the ground potential, are illustrated respectively.

[0050] In the example of FIG. 11, the potential distribution of the vehicle 1 does not lead to an overload of the insulation at a DC charging station that is not very strongly insulated. Therefore, the drive units A1, A2 are free with respect to the selection of the transformation ratio.

[0051] In the example of FIG. 12, the potential distribution of the vehicle 1 leads to an overload of the insulation at a DC charging station that is not very strongly insulated at the first high voltage potential P1. Therefore, as shown here, the second drive unit A2 raises the second high voltage potential P2 with a relatively low transformation ratio or is passively directly connected. The first drive unit A1 raises the first high voltage potential P1 with a relatively high transformation ratio.

[0052] In the example of FIG. 13, the potential distribution of vehicle 1 at the second high voltage potential P2 will lead to an overload of insulation in a DC charging station that is not insulated very strongly. Therefore, the first drive unit A1 either raises the first high voltage potential P1 with a relatively low transformation ratio or is passively connected in a direct-through manner as shown here. The second drive unit A2 raises the second high voltage potential P2 with a relatively high transformation ratio.

[0053] The reaction of the circuit device 2 to the asymmetric potential distribution of the two drive units A1, A2, which are electrically connected in series in particular in the manner described above, can be carried out as described, for example, in German Patent Application Publication No. 102017009352, in particular by controlling and / or controlling the inverters I1, I2, in particular their inverter circuits IS1, IS2.

[0054] The insulation strength at the charging stand is observed for the charging operation described above, in particular due to the potential shift by the insulation monitor carried out at that time, as well as in the case of asymmetric insulation resistance and / or insulation faults occurring at low speeds.

[0055] Compatibility with the insulation monitor is ensured, for example, by the method described in the following publication. PCIM 2021, Quasi-Isolated HV / HV-DC / DC-Converter for Electric Driven Vehicles with Multiple High-Voltage Levels, Andre Haspel, Urs Bohme, Mercedes-Benz AG, Germany.

[0056] Yet another drawback of the galvanically coupled DC-DC converter that is avoided by the solution described above is that in the case of a galvanically coupled DC-DC converter, if an insulation fault occurs in vehicle 1, as a direct consequence, an additional insulation fault may occur on the side of the DC charging station at the mutual high voltage potentials P2, P1. Thereby, a short circuit of the traction battery 4 occurs, which in the so-called CHAdeMO charging standard leads to a breakage of the ground potential line ML in the charging cable 6 through which the electrical connection part 5 of vehicle 1 is electrically connected to the DC charging station. This is because such a ground potential line ML of the charging cable 6 is made very thin.

[0057] Figure 14 shows a solution to this problem according to the embodiment of FIG. 1, and FIG. 15 shows a solution to this problem according to the embodiment of FIG. 6. Vehicle 1 having the circuit device 2, here particularly the chassis 7 of vehicle 1, and an electrical unit 3 outside the vehicle configured as a DC charging station, here particularly having a metal housing 8, are each shown. The DC charging station has, by way of example, a design voltage and / or charging voltage of 500V. The traction battery 4 has, by way of example, a rated voltage of 800V.

[0058] An insulation fault F1 has occurred in vehicle 1. As a direct consequence of the resulting overload of insulation at the DC charging station, an insulation fault F2 also occurs here, based on the application of the 800V voltage of the traction battery 4. The resulting battery short-circuit current KS is indicated by the arrow.

[0059] Here, for example, during the step-down operation for supplying to a public energy supply network, i.e., during the supply of electrical energy from the traction battery 4 to the electrical unit 3 outside the vehicle configured as a DC charging station, each critical operating state is shown. The insulation fault F1 of the vehicle 1 occurs from the first high voltage potential P1 to the reference potential M, in particular to the ground potential, i.e., in particular to the chassis 7 of the vehicle 1. And the rise of the short-circuit current is delayed by the motor windings U2, V2, and W2 of the second drive unit A2, so that the monitoring system has sufficient time to recognize the occurrence of an error, for example, by current measurement and / or voltage measurement, and no overload / damage occurs in the ground potential line ML of the charging cable 6, the DC charging station, or a part of the vehicle 1. The step-down operation is stopped by opening the inverter switching units IE8, IE10, IE12 configured as semiconductor switching units in particular. The current applied in the motor windings U2, V2, and W2 is further carried through the freewheeling body diodes of the inverter switching units IE7, IE9, IE11, and the energy of the inductance including the inductance of the supply line is recharged by the capacitor C1. Subsequently, the short-circuit current is reduced to 0 A completely.

[0060] The second high voltage potential P2 HV-insulation fault with respect to the reference potential M in the vehicle 1, in particular with respect to the ground potential, will lead to an overload of the first high voltage potential P1 with respect to the reference potential M in the DC charging station, in particular with respect to the ground potential. Such a current can also be interrupted according to the same principle, in which case the corresponding components of the first drive unit A1 are targeted.

[0061] In this way, the reaction means for the short circuit occurring based on the insulation fault F1 in the vehicle 1 is provided by the delay of the current rise due to the motor inductance. Thereby, sufficient time is generated for uniquely recognizing the occurrence of an error and for interrupting the current. The current applied by the motor inductance can be recharged to the capacitance through the freewheeling / body diode.

Description of Symbols

[0062] 1 Vehicle 2 Circuit device 3 Electrical unit outside the vehicle 4 Traction battery 5 Connection part 6 Charging cable 7 Chassis 8 Metal housing A1, A2 Drive unit AB1, AB2 Generation of current C1, C2 Capacitor F1, F2 Insulation failure FL1, FL2 Freewheeling of current I1, I2 Inverter IE1 to IE12 Inverter switching unit IS1, IS2 Inverter circuit KS Battery short-circuit current M Reference potential M1, M2 Three-phase machine ML Ground potential line P1, P2 High voltage potential PL1, PL2 Potential line Rb Internal resistance of the traction battery Rg Internal resistance of the DC charging station S1 to S6 Switch SP1, SP2 Neutral point U1, V1, W1 Motor winding U2, V2, W2 Motor winding

Claims

1. A vehicle (1) having an electrical circuit device (2), wherein the electrical circuit device (2) comprises: a traction battery (4); an electrical connection part (5) for electrical connection with an electrical unit (3) outside the vehicle; a first high voltage potential (P1); a second high voltage potential (P2); wherein the first high voltage potential (P1) is a positive high voltage potential and the second high voltage potential (P2) is a negative high voltage potential, or vice versa; the circuit device (2) further comprises: two electric drive units (A1, A2) each having an inverter (I1, I2) and a three-phase electric machine (M1, M2) electrically connected thereto, for driving the vehicle (1); the two electric drive units (A1, A2) are electrically connectable in series between the electrical connection part (5) and the traction battery (4), such that the first electric drive unit (A1) raises the first high voltage potential (P1) from the electrical connection part (5) to the traction battery (4), and the second electric drive unit (A2) raises the second high voltage potential (P2); in the vehicle (1), each inverter (I1, I2) has a capacitor (C1, C2) between a potential line (PL1) of the first high voltage potential (P1) and a potential line (PL2) of the second high voltage potential (P2); the circuit device (2) is configured such that the second electric drive unit (A2) is electrically connectable in series with a capacitor connection part of the first electric drive unit (A1). The vehicle (1) is characterized by this.

2. One of the potential lines (PL1, Pl2) of the inverter (I2) of the second electric drive unit (A2) is electrically connected to a capacitor connection contact of the capacitor connection part of the inverter (I1) of the first drive unit (A1), which has the same high voltage potential (P1, P2). The circuit device (2) comprises: The neutral point (SP2) of the three-phase electric machine (M2) of the second electric drive unit (A2) can be electrically connected to another capacitor connection point of the inverter (I1) of the first electric drive unit (A1), and the potential lines (PL1, PL2) of the inverter (I1) electrically connected to the capacitor connection point can be electrically connected to connection points of the electrical connection part (5) having the same high voltage potential (P1, P2). The neutral point (SP1) of the three-phase electric machine (M1) of the first electric drive unit (A1) is configured to be electrically connectable to another connection point of the electrical connection part (5), or The winding connection part of the three-phase electric machine (M2) of the second electric drive unit (A2) can be electrically connected to another capacitor connection point of the inverter (I1) of the first electric drive unit (A1), and the potential lines (PL1, PL2) of the inverter (I1) electrically connected to the capacitor connection point can be electrically connected to connection points of the electrical connection part (5) having the same high voltage potential (P1, P2). The winding connection part of the three-phase electric machine (M) of the first electric drive unit (A1) is configured to be electrically connectable to another connection point of the electrical connection part (5). The vehicle (1) according to claim 1, characterized in that

3. The vehicle (1) according to claim 1 or 2, characterized in that the traction battery (4) is electrically connected to the capacitor connection part of the second electric drive unit (A2).

4. The vehicle (1) according to any one of claims 1 to 3, characterized in that the circuit device (2) is configured such that the traction battery (4) can be electrically connected to the capacitor connection part of the first electric drive unit (A1).

5. The vehicle (1) according to any one of claims 1 to 4, characterized in that the circuit device (2) is configured such that the electrical connection part (5) can be directly electrically connected to the traction battery (4).

6. A method for operating the vehicle (1) according to any one of claims 1 to 5, comprising For charging the traction battery (4) by an electrical unit (3) outside the vehicle configured as a DC charging station electrically connected to the electrical connection part (5) with a charging voltage lower than the rated voltage of the traction battery (4), and / or for providing electrical energy from the traction battery (4) to an electrical unit (3) outside the vehicle electrically connected to the electrical connection part (5), the two electric drive units (A1, A2) are electrically connected in series between the electrical connection part (5) and the traction battery (4), and / or For charging the traction battery (4) by an electrical unit (3) outside the vehicle configured as a DC charging station electrically connected to the electrical connection part (5) with a charging voltage at least as large as the rated voltage of the traction battery (4), the electrical connection part (5) is directly connected to the traction battery (4), and / or For the driving operation of the vehicle (1), both inverters (I1, I2) are directly connected to the traction battery (4) respectively. In the method, For this purpose, the inverters (I1, I2) of the drive units (A1, A2) each have a capacitor (C1, C2) between the potential line (PL1) of the first high voltage potential (P1) and the potential line (PL2) of the second high voltage potential (P2). The method is characterized in that the circuit device (2) can be switched such that the second drive unit (A2) is electrically connected in series with the capacitor connection part of the first electric drive unit (A1).

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