A vehicle having an electrical circuit device and two electric drive units, and a 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 preamble components of claim 1 and to a method of operating such a vehicle.

Background Art

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

[0003] From Patent Document 2, a system for charging an electrical energy accumulator by an electric drive system is known. For electrical insulation between a voltage source and the energy accumulator to be charged, an inductive connection between the respective phase windings or phase strands of the electric machine is intended. For this purpose, the phase windings of the electric machine may be sub-divided 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, comprising a three-phase electric machine, an electrical energy storage device, an inverter for the three-phase electric machine, and a charging connection for connecting the electrical energy storage device to a charging unit. In this system, the switching device has a first switching state in which the charging connection is electrically connected to the electrical energy storage device and the inverter is electrically isolated from the charging connection and the electrical energy storage device. In a second switching state of the switching device, the charging connection is electrically connected to the inverter and the electrical energy storage device, and in a third switching state of the switching device, the inverter is electrically connected to the electrical energy storage device and the charging connection is electrically isolated from the electrical energy storage device and the inverter.

[0005] Furthermore, prior art, as described in Patent Document 4, provides information on energy connectors for electrically connecting in-vehicle electrical systems and methods for electrically connecting in-vehicle electrical systems. An 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 comprises first and second time-controlled energy converters, each having an in-vehicle electrical system connection section and an intermediate circuit connection section. The in-vehicle electrical system connection section 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 sections 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 a second time-controlled energy converter.

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

[0007] From Patent Document 6, a circuit device for a hybrid vehicle or electric vehicle is known. This circuit device includes a high-voltage battery for storing electrical energy, at least one electromachine for driving the hybrid vehicle or electric vehicle, a power converter capable of converting a high-voltage DC voltage available from the high-voltage battery into a high-voltage AC voltage for operating the electromachine, and a charging connection for providing electrical energy for charging the high-voltage battery. The power converter is configured as a three-stage power converter and has at least one switch unit assigned to one phase of the electromachine, each including two series-connected switch groups, each having two series-connected IGBTs, and a connection is positioned between each IGBT of one switch group, which is directly electrically connected to the circuit of the charging connection.

[0008] Patent Document 7 describes an on-board electrical system for an electrically driven vehicle. This on-board electrical system includes a vehicle battery and an inverter electrically connected to the vehicle battery, which includes a multiphase electromechanism and a series circuit for each phase of the electromechanism, each consisting of a switching unit connected in series. Each switching unit in the series circuit provides a central connection to which each phase winding of the electromechanism is connected. The inverter is configured as a three-level inverter, with each switching unit having a series circuit consisting of two switching members connected to each other at a connection point. In at least one of the two switching units of these series circuits, one inductance is connected to each first connection point at each connection point. Each second connection point of the inductance is electrically connectable to the DC voltage charging connection point of the vehicle.

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

[0010] Patent Document 9 describes a charging device for charging an automobile battery, which includes a step-down converter. This charging device includes an electromechanism for driving the automobile and a traction inverter that converts the DC voltage of the battery for the electromechanism during the driving operation of the automobile. The electromechanism, together with the traction inverter, acts as a step-up converter for the battery charging operation. A step-down converter is placed before the step-up converter to reduce the input DC voltage to a level that is suitable for charging the battery after it has been boosted by the step-up converter.

[0011] From Patent Document 10, an on-board electrical system is known that has an inverter and a DC-DC converter having an energy storage member in the negative path. An on-board electrical system for a partially or fully electrically driven automobile includes an electrical inverter capable of generating an AC voltage from a DC voltage for a first operating state of the automobile and capable of generating a DC voltage from an AC voltage for a second operating state of the automobile, and at least one galvanically coupled DC-DC converter that is wired to the electrical inverter on the DC voltage side of the electrical inverter. The 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] DE102018000465A1 [Patent Document 2] DE102019209786A1 [Patent Document 3] DE102021003851A1 [Patent Document 4] DE102017009352A1 [Patent Document 5] DE102018009840A1 [Patent Document 6] DE102018009848A1 [Patent Document 7] DE102019005621A1 [Patent Document 8] DE102018000488A1 [Patent Document 9] DE102009052680A1 [Patent Document 10] DE102018000580A1 [Overview of the Initiative] [Problems that the invention aims to solve]

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

[0014] According to the present invention, this problem is solved by a vehicle having the features of claim 1, and claim 5 This is resolved by a method of operating this vehicle, which has the following characteristics. Advantageous embodiments of the present invention are subject to the dependent claims.

[0015] The vehicle has an electrical circuit system. This circuit system includes a traction battery, electrical connections for electrical connections to external electrical units, a first high-voltage potential, and a second high-voltage potential, where the first high-voltage potential is a positive high-voltage potential and the second high-voltage potential is a negative high-voltage potential, or vice versa. The term "high voltage," also abbreviated as HV, specifically refers to an electrical DC voltage greater than approximately 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 for driving a vehicle, each having an inverter and a three-phase electromechanical unit electrically connected thereto. A traction battery is provided, in particular, to supply electrical energy to these drive units for driving 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, that is, 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 that is formed by two electric drive units, that is, by the above-described wiring, between the electrical connection and the traction battery and operates in the above-described manner. 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, that is, the positive and negative signs are not taken into account.

[0018] Thus, the solution according to the present invention makes it possible to utilize the electric drive unit already present in the vehicle as a DC-DC converter and thus provide it for additional uses. In particular, it makes it possible to charge the traction battery by an external electrical unit configured as a DC charging station electrically connected to an electrical connection, with a charging voltage lower than the rated voltage of the traction battery. Furthermore, energy supply in the opposite direction, also known as step-down operation, is also possible. In this case, electrical energy is supplied by the traction battery to an external electrical unit electrically connected to an electrical connection, for example, to supply the traction battery's electrical energy to a public energy supply network or a building's energy supply network, particularly via a DC charging station electrically connected to an electrical connection. Such bidirectional energy supply is also known as bidirectional charging. The solution of the present invention eliminates the need to install an additional DC-DC converter in the vehicle, thereby achieving considerable reductions in design space, weight, and cost. The solution of the present invention eliminates the need for other solutions to enable charging of the traction battery at a relatively low charging voltage, and for example, it eliminates the need to configure the traction battery as a switching battery to enable charging by a modified circuit of the traction battery's battery module.

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

[0020] With 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, for example, 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 an 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 a potential line of a first high voltage potential and a potential line of a second high voltage potential. At this time, the circuit device is configured to be able to connect a second electric drive unit in series with a 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 this case, in order to enable the electrical series circuit of the two drive units as described above, the circuit device is intended to be configured such that the neutral point of the three-phase electric machine of the second electric drive unit is electrically connectable to the other capacitor connection contact of the capacitor connection of the inverter of the first electric drive unit, the potential line of the inverter that is electrically connected to the capacitor connection contact is electrically connectable to the connection contact of the electrical connection having the same high voltage potential, and the neutral point of the first three-phase electric machine is electrically connectable to the other connection contact of the electrical connection. As an alternative, in order to enable the electrical series circuit of the two drive units described above, the circuit device is intended to be configured such that, for example, the winding connection of the three-phase electric machine of the second electric drive unit is electrically connectable to other capacitor connection contacts of the capacitor connection of the inverter of the first electric drive unit, the potential line of the inverter that is electrically connected to said capacitor connection contacts is electrically connectable to the connection contacts of the electrical connection having the same high voltage potential, and the winding connection of the three-phase electric machine of the first electric drive unit is electrically connectable to other connection contacts of the electrical connection.

[0024] In particular, the traction battery is intended to be electrically connected to the capacitor connection of the second electric drive unit. Furthermore, in order to further enable the basic functions of the electric drive units, namely the driving of the vehicle, it is preferable that the circuit is configured such that the traction battery can be electrically connected to the capacitor connection of the first electric drive unit. This allows the traction battery to supply electrical energy to both electric drive units. Thus, in the method of operating the vehicle, both inverters are intended to be directly connected to the traction battery for the vehicle's driving operation.

[0025] In one possible embodiment of the vehicle, the circuitry is intended to be configured such that the electrical connection is directly electrically connectable to the traction battery. This also makes it possible to charge the traction battery by an external electrical unit configured as a DC charging station electrically connected to the electrical connection, the charging voltage of which is at least the same 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 of the traction battery by an external electrical unit configured as a DC charging station electrically connected to the electrical connection, the charging voltage of which is at least the same as the rated voltage of the traction battery.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Brief explanation of the drawing]

[0027] [Figure 1] A schematic representation of a vehicle having a switching device is shown. [Figure 2] The current increase in the switching device shown in Figure 1 during charging operation is schematically illustrated. [Figure 3] The freewheeling of current in the switching device shown in Figure 1 during charging operation is schematically illustrated. [Figure 4] Figure 1 schematically shows the current increase in the switching device during step-down operation. [Figure 5] Figure 1 schematically illustrates the freewheeling of current in the switching device during step-down operation. [Figure 6] Another embodiment of a vehicle having a switching device is schematically shown. [Figure 7] Figure 6 schematically illustrates the current increase in the switching device during charging operation. [Figure 8] Figure 6 schematically illustrates the freewheeling of current in the switching device during charging operation. [Figure 9]Figure 6 schematically illustrates the current increase in the switching device during step-down operation. [Figure 10] Figure 6 schematically illustrates the freewheeling of current in the switching device during step-down operation. [Figure 11] An example of DC voltage conversion using a switching device is schematically shown. [Figure 12] Another example of DC voltage conversion using a switching device is schematically shown. [Figure 13] Another example of DC voltage conversion using a switching device is schematically shown. [Figure 14] Figure 1 schematically illustrates an embodiment of a short circuit in a vehicle. [Figure 15] Figure 6 schematically illustrates an embodiment of a short circuit in a vehicle. [Modes for carrying out the invention]

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

[0029] Figures 1 and 6 illustrate two embodiments of a vehicle 1 having an electrical circuit device 2. In both embodiments shown, the vehicle 1 is electrically connected to an external electrical unit 3 configured as a DC charging station. The internal resistance Rg of the DC charging station is also shown in each embodiment.

[0030] The circuit device 2 includes a traction battery 4, the internal resistance Rb of the traction battery 4 is also shown here, and further includes an electrical connection part 5 for electrical connection to an external electrical unit 3, 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 and A2 for driving the vehicle 1, each having inverters I1 and I2 and three-phase electric machines M1 and M2 electrically connected thereto.

[0032] In both embodiments, the circuit device 2 is configured such that both electric drive units A1 and A2 can be electrically connected in series between the electrical connection 5 and the traction battery 4, thereby enabling the first electric drive unit A1 to raise a first high voltage potential P1 from the electrical connection 5 to the traction battery 4, and the second electric drive unit A2 to raise or lower a second high voltage potential P2. In this solution, the drive units A1 and A2 wired in this manner constitute a DC-DC converter, which enables so-called bidirectional charging, namely, in one direction the traction battery 4 is charged by an external electrical unit 3 configured as a DC charging station electrically connected to the electrical connection 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 electrical unit 3 electrically connected to the electrical connection 5.

[0033] Inverters I1 and I2 each have inverter circuits IS1 and IS2, respectively, which include, in particular as shown herein, a plurality of inverter circuit units IE1 to IE12, in particular semiconductor switching units, in particular transistors, in particular bipolar transistors having isolated gate electrodes, in particular diodes configured as freewheeling body diodes. Inverter circuits IS1 and IS2 are positioned, 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 each inverter I1 and I2. The three-phase machines M1 and M2 of the respective drive units A1 and A2 have three motor windings U1, V1, W1, U2, V2, and W2 connected in a star configuration to the inverters I1 and I2 of the drive units A1 and A2 in the manner shown herein.

[0034] Furthermore, inverters I1 and I2 each have capacitors C1 and C2 between their two potential lines PL1 and PL2, respectively. 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 electric drive unit A2 can be electrically connected in series with the capacitor connection of the first electric drive unit A1. To this end, one of the potential lines of inverter I2 of the second electric drive unit A2 (the first potential line PL1 in this example) is electrically connected to the capacitor connection contact of the capacitor connection of inverter I1 of the first drive unit A1, which has the same high voltage potential (the first high voltage potential P1 in this example).

[0035] Furthermore, in the first embodiment shown in Figure 1, the circuit device 2 is configured such that the neutral point SP2 of the three-phase electromechanism M2 of the second electric drive unit A2 can be electrically connected to other capacitor connection contacts of the capacitor connection section of the inverter I1 of the first electric drive unit A1 when the first switch S1 is closed in this example; the potential line PL2 of the inverter I1, which is electrically connected to said capacitor connection contacts, can be electrically connected to the connection contacts of the electrical connection section 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 electromechanism M1 of the first electric drive unit A1 can be electrically connected to other connection contacts of the electrical connection section 5 when the third switch S3 is closed in this example.

[0036] In another embodiment shown in Figure 6, as an alternative, the winding connection of the three-phase electric machine M2 of the second electric drive unit A2 is electrically connectable to other capacitor connection contacts of the inverter I1 of the first electric drive unit A1 when the first switch S1 is closed in this example, and the potential line PL2 of the inverter I1, which is electrically connected to said capacitor connection contacts, is electrically connectable to the connection contacts of the electrical connection section 5 having the same high voltage potential P2 when the second switch S2 is closed in this example, and the winding connection of the three-phase electric machine M1 of the first electric drive unit A1 is electrically connectable to other connection contacts of the electrical connection section 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. This enables charging of the traction battery 4 as described above, and enables the vehicle 1 to run. In order to perform the running operation, the circuit device 2 is further intended to be configured such that, in this example, the traction battery 4 can be electrically connected to the capacitor connection of the first electric drive unit A1 when the fourth switch S4 is closed. This switch connects the second potential line PL2 of the inverter I1 of the first electric drive unit A1 to the second high voltage potential P2 of the traction battery 4, in the illustrated embodiment.

[0038] Furthermore, the circuit device 2 enables the traction battery 4 to be charged by an external electrical unit 3 configured as a DC charging station that is electrically connected to an electrical connection 5, the charging voltage of which is at least the same as the rated voltage of the traction battery 4. To this end, the circuit device 2 is configured such that, in both embodiments, the fifth and sixth switches S5 and S6 are closed, allowing the electrical connection 5 to be directly electrically connected to the traction battery 4, thereby directly connecting the high-voltage potentials P1 and P2 of the traction battery 4 and the external electrical unit 3 to each other by corresponding direct potential lines PL1 and PL2.

[0039] Switches S1 to S6 are configured, for example, as contactors.

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

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

[0042] The electrical connection 5 is intended to be directly connected to the traction battery 4 for charging of the traction battery 4 by an external electrical unit 3 configured as a DC charging station that is electrically connected to the electrical connection 5, the charging voltage of which is at least the same as the rated voltage of the traction battery 4. For this purpose, in the embodiments shown in Figures 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 vehicle 1 to run, both inverters I1 and I2 are directly connected to the traction battery 4. In the embodiments shown in Figures 1 and 6, switch S4 is closed and the other switches S1, S2, S3, S5, and S6 are opened.

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

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

[0046] Figures 4 and 9 show, for each embodiment of Figures 1 to 6, the current increase AB1 in the motor windings U1, V1, and W1 of the first drive unit A1 is indicated by solid arrows, and the current increase AB2 in the motor windings U2, V2, and W2 of the second drive unit A2 is indicated by dashed arrows, regarding the provision of electrical energy by the traction battery 4 to the external electrical unit 3 that is electrically connected to the electrical connection part 5.

[0047] Figures 5 and 10 show, for each embodiment of Figures 1 to 6, the provision of electrical energy by the traction battery 4 to the external electrical unit 3 electrically connected to the electrical connection part 5, with solid arrows indicating the freewheeling FL1 of the current in the motor windings U1, V1, and W1 of the first drive unit A1, and with dashed arrows indicating the freewheeling FL2 of the current in the motor windings U2, V2, and W2 of the second drive unit A2.

[0048] Furthermore, the aforementioned solution avoids the drawbacks of galvanically coupled DC-DC converters. This is because such DC-DC converters cause a potential shift only at one high-voltage potential P1, P2, while the other high-voltage potential P2, P1 is directly connected from the DC charging station to vehicle 1. This can lead to overloading of the insulation during the charging process. This may be due to an asymmetrical insulation resistance distribution in the DC charging station and / or vehicle 1. Moreover, insulation monitoring can also lead to potential shifts that could result in insulation overload at the DC charging station.

[0049] In contrast, the solution described here allows for the control of the potential shift of both potentials P1 and P2, as illustrated in Figures 11 to 13. Here, the charging of a traction battery 4 with a rated voltage of 800V is shown at a DC charging station with a charging voltage of 400V. The two potentials P1 and P2 from the DC charging station on the left to the traction battery 4 on the right, and the reference potential M with 0V, specifically the ground potential, are illustrated, respectively.

[0050] In the example shown in Figure 11, the potential distribution of vehicle 1 does not lead to an insulation overload at the DC charging station, which is not very well insulated. Therefore, drive units A1 and A2 are free to choose their transformer ratio.

[0051] In the example shown in Figure 12, the potential distribution of vehicle 1 leads to an overload of insulation at the DC charging station, which is not very well insulated, at the first high voltage potential P1. Therefore, the second drive unit A2 either pulls up the second high voltage potential P2 with a relatively low transformation ratio, as shown here, or is passively passed through. The first drive unit A1 pulls up the first high voltage potential P1 with a relatively high transformation ratio.

[0052] In the example shown in Figure 13, the potential distribution of vehicle 1 would lead to an overload of insulation at the DC charging station, which is not very well insulated, at the second high-voltage potential P2. Therefore, the first drive unit A1 either pulls up the first high-voltage potential P1 with a relatively low transformation ratio or is passively connected as shown here. The second drive unit A2 pulls up the second high-voltage potential P2 with a relatively high transformation ratio.

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

[0054] The insulation strength at the charging station is observed for the charging operation described above, particularly in the event of potential shifts due to insulation monitoring performed during the operation, as well as in the case of asymmetric insulation resistance and / or insulation failures occurring at low speeds.

[0055] Compatibility with the insulation monitor is ensured by the method described, for example, 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] Another drawback of galvanically coupled DC-DC converters, which can be avoided by the solutions described above, is that if an insulation failure occurs in the vehicle 1, it can directly result in further insulation failure at the mutual high-voltage potentials P2 and P1 on the DC charging station side. This can lead to a short circuit in the traction battery 4, which in the so-called CHAdeMO charging standard leads to damage to the ground potential wire ML in the charging cable 6, which electrically connects the electrical connection point 5 of the vehicle 1 to the DC charging station. This is because such a ground potential wire ML in the charging cable 6 is manufactured to be very thin.

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

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

[0059] Here, critical operating conditions are shown, for example, during a step-down operation to supply power to the public energy grid, i.e., during the supply of electrical energy from the traction battery 4 to an external electrical unit 3 configured as a DC charging station. The insulation failure F1 of 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 vehicle 1. The rise in short-circuit current is delayed by the motor windings U2, V2 and W2 of the second drive unit A2, thereby giving the monitoring system sufficient time to recognize the occurrence of the error, for example by current measurement and / or voltage measurement, and preventing overload / damage to the ground potential wire ML of the charging cable 6, the DC charging station, or any part of vehicle 1. The step-down operation is stopped by opening the inverter switching units IE8, IE10, and IE12, which are configured in particular as semiconductor switching units. The current applied to the motor windings U2, V2, and W2 is further carried through the freewheeling body diodes of the inverter switching units IE7, IE9, and IE11, and the inductance energy, including the inductance of the supply line, is recharged in capacitor C1. Subsequently, the short-circuit current is reduced to 0A overall.

[0060] A second high-voltage potential P2 HV in vehicle 1, relative to the reference potential M and especially to the ground potential, will result in a corresponding overload of the first high-voltage potential P1 in the DC charging station relative to the reference potential M and especially to the ground potential. Such currents can also be interrupted according to the same principle, in which case the relevant component of the first drive unit A1 will be affected.

[0061] Thus, the response to a short circuit caused by an insulation failure F1 in vehicle 1 is provided by the delay in the current rise due to the motor inductance. This provides sufficient time to uniquely recognize the occurrence of the error and to interrupt the current. The current applied to the motor inductance can be recharged into the capacitance via the freewheeling / body diode. [Explanation of symbols]

[0062] 1 vehicle 2 circuit device 3. Electrical units on the exterior of the vehicle 4 Traction Battery 5 Connection part 6 Charging Cables 7 Chassis 8 Metal Housing A1, A2 drive unit AB1, AB2 Current Generation C1, C2 Capacitors F1, F2 Insulation failure FL1, FL2 current freewheeling 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 wire P1, P2 High voltage potential PL1, PL2 potential line Rb Traction Battery Internal Resistance Internal resistance of RG DC charging station S1 to S6 Switch SP1, SP2 Neutral point U1, V1, W1 motor windings U2, V2, W2 motor windings

Claims

1. A vehicle (1) having an electrical circuit device (2), The aforementioned electrical circuit device (2) is Traction battery (4) and An electrical connection part (5) for electrical connection to an external electrical unit (3) of the vehicle, The first high voltage potential (P1), It has a second high voltage potential (P2), 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 aforementioned electrical circuit device (2) is The vehicle (1) has two electric drive units (A1, A2), each having inverters (I1, I2) and three-phase electric machines (M1, M2) electrically connected thereto, for driving the vehicle (1). The two electric drive units (A1, A2) are electrically connected in series between the electrical connection (5) and the traction battery (4), so that the first electric drive unit (A1) raises the first high voltage potential (P1) from the electrical connection (5) to the traction battery (4), and the second electric drive unit (A2) raises the second high voltage potential (P2). The inverters (I1, I2) each have capacitors (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). In the vehicle (1), the electrical circuit device (2) is configured such that the second electric drive unit (A2) can be electrically connected in series with the capacitor connection portion of the first electric drive unit (A1), One of the potential lines (PL1, Pl2) of the inverter (I2) of the second electric drive unit (A2) is electrically connected to the capacitor connection contact of the capacitor connection part of the inverter (I1) of the first electric drive unit (A1), which has the same high voltage potential (P1, P2), and the electrical circuit device (2) is, The neutral point (SP2) of the three-phase electric machine (M2) of the second electric drive unit (A2) is electrically connectable to other capacitor connection contacts of the inverter (I1) of the first electric drive unit (A1), the potential lines (PL1, PL2) of the inverter (I1) that are electrically connected to the capacitor connection contacts are electrically connectable to the connection contacts of the electrical connection section (5) having the same high voltage potential (P1, P2), and 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 other connection contacts of the electrical connection section (5), or The vehicle (1) is characterized in that the winding connection portion of the three-phase electric machine (M2) of the second electric drive unit (A2) is electrically connectable to other capacitor connection contacts of the inverter (I1) of the first electric drive unit (A1), the potential lines (PL1, PL2) of the inverter (I1) that are electrically connected to the capacitor connection contacts are electrically connectable to the connection contacts of the electrical connection portion (5) having the same high voltage potential (P1, P2), and the winding connection portion of the three-phase electric machine (M) of the first electric drive unit (A1) is configured to be electrically connectable to other connection contacts of the electrical connection portion (5).

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

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

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

5. A method for operating the vehicle (1) according to claim 1 or 2, For charging the traction battery (4) by an external electrical unit (3) configured as a DC charging station electrically connected to the electrical connection part (5), where the charging voltage is lower than the rated voltage of the traction battery (4), and / or for supplying electrical energy from the traction battery (4) to the external electrical unit (3) 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), or For charging the traction battery (4) by an external electrical unit (3) configured as a DC charging station electrically connected to the electrical connection part (5), the electrical connection part (5) is directly connected to the traction battery (4) and / or, the charging voltage of which is at least the same as the rated voltage of the traction battery (4). For the driving operation of the vehicle (1), both inverters (I1, I2) are directly connected to the traction battery (4), In the above method, For this purpose, the inverters (I1, I2) of the drive units (A1, A2) each have capacitors (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 electrical circuit device (2) is switched so that the second electric drive unit (A2) is electrically connected in series with the capacitor connection portion of the first electric drive unit (A1), and one of the potential lines (PL1, Pl2) of the inverter (I2) of the second electric drive unit (A2) is electrically connected to the capacitor connection contact of the capacitor connection portion of the inverter (I1) of the first electric drive unit (A1), which has the same high voltage potential (P1, P2).

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