Device and method for determining an insulation resistance for a power converter for a vehicle

Abstract

A device (120) for determining the insulation resistance of a power converter (108) comprises voltage-controlled blocking devices (240, 244) connected in series with blocking resistors (242, 246) between supply terminals (230, 230) and a ground terminal (234), as well as measuring devices (250, 252) connected between the supply terminals (230, 230) and the ground terminal (234) to provide measured values ​​(254, 256). Furthermore, the device (120) comprises an evaluation device (222) configured to determine resistance values ​​Rs1, Rs2 for insulation resistances existing between the supply terminals (230, 230) and the ground terminal (234) using the measured values ​​(254, 256).

Description

[0001] The present invention relates to a device and a method for determining an insulation resistance for a power converter for a vehicle, to a power converter, an electric axle drive and to a motor vehicle.

[0002] Measuring the insulation resistance between the terminals of a power supply and the chassis of a battery-powered system, such as an electric vehicle, is necessary to provide end-user safety in case of material failures due to contamination, aging, maintenance issues, etc. Relays and control circuits can be used for this purpose, switching a known resistance on and off in the circuit. This aids in identifying the resistances through post-processing, for example, of output voltages ISO_POS and ISO_NEG.

[0003] Leakage resistance can also be detected using switches. Switches, along with their drivers and control circuitry, increase costs and can be a burden on cost-effective battery systems. Eliminating them poses a risk of electric shock to the end user.

[0004] Against this background, the present invention provides an improved device and an improved method for determining an insulation resistance for a power converter for a vehicle, an improved power converter, an improved electric axle drive, and an improved motor vehicle according to the main claims. Advantageous embodiments will become apparent from the dependent claims and the following description.

[0005] Advantageously, the insulation resistance of an electrical system, for example a vehicle, can be determined cost-effectively and safely without the use of relays and control circuits that switch a known resistance on and off in a circuit.

[0006] A device for determining the insulation resistance of a power converter, in particular a traction converter for a vehicle, has the following features: a first supply connection for applying a first potential of a supply voltage Vin and a second supply connection for applying a second potential of the supply voltage Vin; a ground connection; a first voltage-controlled blocking device connected in series with a first blocking resistor between the first supply terminal and the ground terminal, and a second voltage-controlled blocking device connected in series with a second blocking resistor between the second supply terminal and the ground terminal; a first measuring device which is connected between the first supply terminal and the ground terminal and is designed to obtain a positive measured value V HV_SENS_POS , to provide VPsns and a second measuring device connected between the second supply terminal and the ground terminal and configured to obtain a negative measured value V HV_SENS_NEG , provide VNsns; and an evaluation device that is designed to use the positive measured value V HV_SENS_POS , VPsns and the negative measured value V HV_SENS_NEG, VNsns to determine a first resistance value Rs1 for a first insulation resistance existing between the first supply terminal and the ground terminal and a second resistance value Rs2 for a second insulation resistance existing between the second supply terminal and the ground terminal.

[0007] The power converter can be used, for example, to convert the supply voltage from DC to AC or another DC voltage. The supply voltage can be used to operate an electrical system, such as a vehicle that is at least partially electrically powered. For example, the supply voltage can represent an intermediate circuit voltage. During a switch-on process, the supply voltage can be increased gradually to a target value rather than abruptly. During a switch-off process, the supply voltage can also be reduced continuously to zero, rather than abruptly. In a fault-free state, the supply terminals can be electrically isolated from the ground terminal to prevent unwanted current flow. In a faulty state, this isolation can be at least partially bridged, allowing unwanted current flow.Such faulty insulation can be detected by determining the magnitude of the insulation resistance. Advantageously, the magnitude of the insulation resistance can be detected early during a switch-on process, thus preventing further increases in the supply voltage.

[0008] Voltage-controlled blocking devices and measuring devices can be components of an electrical circuit. Advantageously, the voltage-controlled blocking devices can be operated without logic control circuits, but rather using electrical voltages present in the circuit. For example, the first voltage-controlled blocking device can be in either a blocking or a conducting state depending on an electrical voltage applied between the first supply terminal and the ground terminal. Similarly, the second voltage-controlled blocking device can be in either a blocking or a conducting state depending on an electrical voltage applied between the ground terminal and the second supply terminal. A blocking device can thus be implemented, for example, using a Zener diode or an input-controlled switch.The two blocking devices can be implemented using identical or different components. The blocking resistors can be implemented using suitable resistive elements or line resistors. A blocking resistor can also be implemented together with the blocking device connected in series in a single element. The measuring devices can be configured to measure electrical voltages present in the electrical circuit in a suitable manner. The measured values ​​provided by the measuring devices can represent the measured voltages and, depending on the embodiment, can be used by the evaluation device directly or after preprocessing to determine the resistance values ​​of the insulation resistances. Positive and negative in connection with the measured values ​​can be understood merely as designations and not indicate a sign.In addition to measured values, the evaluation unit can use known values ​​of circuit components and, additionally or alternatively, predefined values ​​for these components. These values ​​can be set to predetermined levels depending on the current phase of the supply voltage. Different phases of the supply voltage can be assigned different voltage ranges. The evaluation unit can, for example, be implemented as an integrated circuit. It can be configured to provide the resistance values ​​to a higher-level control unit or to use them directly to control a supply voltage parameter.

[0009] The evaluation unit can be configured to provide a control signal, using the first resistance value Rs1 and the second resistance value Rs2, to enable or disable a change in the supply voltage Vin towards a target value. In this way, for example, a further increase in the supply voltage can be prevented if at least one of the resistance values ​​indicates a faulty insulation to ground.

[0010] The first measuring device can be configured to provide the positive measured value as a positive voltage value VPsns, and the second measuring device can be configured to provide the negative measured value as a negative voltage value VNsns. In this case, the evaluation device can be configured to determine the first resistance value Rs1 and the second resistance value Rs2 using the positive voltage value VPsns and the negative voltage value VNsns. Advantageously, the measured values ​​can be processed by the evaluation device without further preprocessing.

[0011] The first measuring device is designed to register the positive measured value as a preliminary positive voltage value V. HV_SENS_POS and the second measuring device can be configured to register the negative measured value as a preliminary negative voltage value V HV_SENS_NEGto provide. The evaluation device can be configured to provide a positive voltage value VPsns using the preliminary positive voltage value V. HV_SENS_POS and a negative voltage value VNsns using the preliminary negative voltage value V HV_SENS_NEG to determine the first resistance value Rs1 and the second resistance value Rs2 using the positive voltage value VPsns and the negative voltage value VNsns. Further processing of the measured values ​​allows for adaptation to differently configured measuring devices.

[0012] The evaluation unit can be configured to determine the first resistance value Rs1 and the second resistance value Rs2 using a positive voltage value VPsns_p1 and a negative voltage value VNsns_p1 assigned to a first phase, as well as a further positive voltage value VPsns_p2 and a further negative voltage value VNsns_p2 assigned to a second phase. The first phase can represent a voltage range of the supply voltage Vin, and the second phase can represent a different voltage range of the supply voltage Vin. This allows the resistance values ​​to be determined, for example, during the supply voltage ramp-up. Advantageously, it is not necessary for the phases to follow each other directly. Thus, for example, an entire ramp-up process of the supply voltage can be monitored.The voltage values ​​of at least the first phase mentioned can be temporarily stored for further use.

[0013] The evaluation device can be configured to determine the presence of the first phase if a positive threshold voltage VP_CHsns determined using the positive voltage value VPsns is less than the magnitude of a first breakdown voltage Vz1 of the first voltage-controlled blocking device and a negative threshold voltage VN_CHsns determined using the negative voltage value VNsns is less than the magnitude of a second breakdown voltage Vz2 of the second voltage-controlled blocking device.

[0014] Accordingly, the evaluation device can be configured to determine the presence of a first second phase if the positive threshold voltage VP_CHsns is greater than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is less than the magnitude of the second breakdown voltage Vz2, and wherein the evaluation device is configured to determine the presence of a second second phase if the positive threshold voltage VP_CHsns is less than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is greater than the magnitude of the second breakdown voltage Vz2.

[0015] Accordingly, the evaluation device can be designed to determine the presence of a third phase if the positive threshold voltage VP_CHsns is greater than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is greater than the magnitude of the second breakdown voltage Vz2.

[0016] This allows the entire ramp-up or ramp-down process of the supply voltage to be divided into phases that can be identified using the evaluation unit.

[0017] The evaluation device can be configured to determine the first resistance value Rs1 and the second resistance value Rs2 using a first set resistance value Rz1_sel for the first blocking resistance, a first set voltage value Vz1_sel for the first breakdown voltage Vz1, a second set resistance value Rz2_sel for the second blocking resistance, and a second set voltage value Vz2_sel for the second breakdown voltage Vz1.

[0018] In this process, when the first second phase is present, the first set resistance value Rz1_sel can be set to a first real resistance value Rz1 of the first blocking resistor, the first set voltage value Vz1_sel to the first breakdown voltage Vz1, the second set resistance value Rz2_sel to a predetermined first value, and the second set voltage value Vz2_sel to zero.

[0019] When the second phase is present, the first set resistance value Rz1_sel can be set to a predetermined first value, the first set voltage value Vz1_sel to zero, the second set resistance value Rz2_sel to a second real resistance value Rz2 of the second blocking resistor, and the second set voltage value Vz2_sel to the second breakdown voltage Vz1.

[0020] When the third phase is present, the first set resistance value Rz1_sel can be set to the first real resistance value Rz1, the first set voltage value Vz1_sel to the first breakdown voltage Vz1, the second set resistance value Rz2_sel to the second real resistance value Rz2, and the second set voltage value Vz2_sel to the second breakdown voltage Vz1.

[0021] Predetermined values ​​for the set resistance values ​​can be, for example, values ​​greater than 100 MOhm, such as 1000 MOhm.

[0022] The first voltage-controlled blocking circuit can include a first Zener diode. The second voltage-controlled blocking circuit can include a second Zener diode. Using a Zener diode allows for a simpler circuit design.

[0023] The first voltage-controlled blocking device can comprise a first switch and a first voltage divider connected between the first supply terminal and the ground terminal to provide a first switching signal for switching the first switch. The second voltage-controlled blocking device can comprise a second switch and a second voltage divider connected between the second supply terminal and the ground terminal to provide a second switching signal for switching the second switch. This allows for a very cost-effective implementation. Similarly, one of the blocking devices can be implemented using a suitable diode and the other using a switch.

[0024] The first measuring device can include a first measuring voltage divider connected between the first supply terminal and the ground terminal to detect the positive voltage value VPsns. The second measuring device can include a second measuring voltage divider connected between the second supply terminal and the ground terminal to detect the negative voltage value VNsns. This allows the measuring devices to be implemented very cost-effectively.

[0025] The first measuring device can use a first operational amplifier connected between the first supply terminal and the ground terminal to detect the preliminary positive voltage value V. HV_SENS_POS The second measuring device may include a second operational amplifier connected between the second supply terminal and the ground terminal to detect the preliminary negative voltage value V. HV_SENS_NEGThis includes [the following]. This enables very accurate voltage measurement.

[0026] A power converter, in particular an inverter for a vehicle, may include such a device.

[0027] An electric axle drive for a motor vehicle can comprise at least one electric machine, a transmission unit, and a power converter. The electric axle drive is characterized by the fact that the power converter is designed as described.

[0028] The transmission device may include a gearbox for reducing the speed of the electric machine as well as a differential.

[0029] A corresponding motor vehicle may include a specified electric axle drive and / or a specified power converter. The motor vehicle is characterized by the fact that the electric axle drive and / or the power converter are designed as described.

[0030] A method for determining an insulation resistance for a power converter, in particular a traction converter for a vehicle, can be implemented using a circuit comprising a first supply terminal for applying a first potential of a supply voltage Vin, a second supply terminal for applying a second potential of the supply voltage Vin, a ground terminal, a first voltage-controlled blocking device connected in series with a first blocking resistor between the first supply terminal and the ground terminal, a second voltage-controlled blocking device connected in series with a second blocking resistor between the second supply terminal and the ground terminal, and a first measuring device connected between the first supply terminal and the ground terminal and configured to measure a positive measured value V. HV_SENS_POS, to provide VPsns, and includes a second measuring device connected between the second supply terminal and the ground terminal and configured to provide a negative measured value V HV_SENS_NEG , to provide VNsns. The procedure comprises a step of determining a first resistance value Rs1 for a first insulation resistance existing between the first supply terminal and the ground terminal and a second resistance value Rs2 for a second insulation resistance existing between the second supply terminal and the ground terminal using the positive measured value V HV_SENS_POS , VPsns and the negative measured value V HV_SENS_NEG , VNsns.

[0031] This determination step, and optionally further steps, can be performed using an evaluation unit. The evaluation unit can be an electrical device that processes electrical signals, such as sensor signals, and outputs control signals accordingly. The evaluation unit can have one or more suitable interfaces, which can be implemented in hardware and / or software. In the case of a hardware implementation, the interfaces can, for example, be part of an integrated circuit in which the device's functions are implemented. The interfaces can also be separate integrated circuits or consist at least partially of discrete components. In the case of a software implementation, the interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.

[0032] It is also advantageous to have a computer program product with program code that can be stored on a machine-readable medium such as semiconductor memory, hard disk memory or optical memory and is used to carry out the method according to one of the embodiments described above when the program is executed on a computer or device.

[0033] The invention is explained in more detail by way of example with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of an exemplary embodiment of a vehicle; Fig. 2 a schematic representation of an exemplary embodiment of a device; Fig. 3 a circuit diagram of an exemplary embodiment of a circuit of a device; Fig. 4 a circuit diagram of an exemplary embodiment of a circuit of a device; Fig. 5 a circuit diagram of an exemplary embodiment of a circuit of a device; Fig. 6 a schematic representation of an exemplary embodiment of a time course of a supply voltage; Fig. 7 a representation of a sequence of different phases of a change in a supply voltage according to an exemplary embodiment; Fig. 8 a flowchart of an exemplary implementation of a process; Fig. 9 a circuit diagram of an exemplary embodiment of a circuit; Fig. 10 simulation results for the in Fig. 9 circuit shown; Fig. 11 a circuit diagram of an exemplary embodiment of a circuit; and Fig. 12 simulation results for the in Fig. Circuit shown in 11.

[0034] In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, without repeating these elements.

[0035] Fig. Figure 1 shows a schematic representation of an embodiment of a vehicle 100, for example, a passenger car or a truck. The vehicle 100 has an electric axle drive for driving the wheels of the vehicle 100. The electric axle drive comprises an electric machine 104, optionally a transmission unit 106, and a power converter 108, which can be, for example, an inverter or a traction converter. The vehicle 100 also has a power supply unit 110, for example, a battery. According to this embodiment, the power converter 108 is connected between the power supply unit 110 and the electric machine 104 and is configured to convert a direct current voltage provided by the power supply unit 110 into an alternating current voltage, for example, a three-phase alternating current voltage, and to supply it to the electric machine 104.The electric machine 104 is designed to provide, when driven by alternating voltage, a torque to drive at least one wheel of the vehicle 100. For this purpose, the electric machine 104 is connected either via the transmission device 106 or directly to an axle or at least one wheel of the vehicle 100.

[0036] A device 120 is provided for determining an insulation resistance between the poles of a supply terminal coupled, for example, to the power supply unit 110 and a ground terminal connected, for example, to the body of the vehicle 100. The device 120 is, by way of example, implemented as a component of the power converter 108, coupled to the power converter 108, or, for example, connected at a suitable position to electrical supply lines supplied by the power supply unit 110.

[0037] The vehicle is shown merely as an example of a system that is at least partially battery-powered and can be monitored using device 120.

[0038] The described approach can therefore be advantageously used for a circuit and a method for measuring the insulation leakage resistances between the poles and the chassis during the gradual increase or gradual decrease of the DC link voltage in a battery-powered HV traction converter system.

[0039] Fig. Figure 2 shows a schematic representation of an embodiment of a device 120 for determining an insulation resistance. The device 120 can be used, for example, in conjunction with a power converter, as shown by Fig. 1 is described.

[0040] The device 120 comprises a circuit 220, an evaluation unit 222, and optionally a device 224 for providing a supply voltage Vin. For example, the device 224 is powered by a battery. The device 224 is configured to gradually increase the supply voltage Vin during a switch-on process and optionally to gradually decrease it during a switch-off process.

[0041] According to one embodiment, the supply voltage Vin corresponds to an intermediate circuit voltage applied to an intermediate circuit capacitor of an intermediate circuit.

[0042] The circuit 220 includes a first supply terminal 230 for applying a first potential of the supply voltage Vin and a second supply terminal 232 for applying a second potential of the supply voltage Vin, as well as a ground terminal 234, which is connected, for example, to the body of a vehicle.

[0043] Circuit 220 comprises a first voltage-controlled blocking device 240, which is connected in series with a first blocking resistor 242 between the first supply terminal 230 and the ground terminal 234. Circuit 220 also comprises a second voltage-controlled blocking device 244, which is connected in series with a second blocking resistor 246 between the second supply terminal 232 and the ground terminal 234.

[0044] According to one embodiment, the first voltage-controlled blocking device 240 is configured to be either blocking or allowing, depending on a voltage applied between the first supply terminal 230 and the ground terminal 234. According to another embodiment, the second voltage-controlled blocking device 244 is configured to be either blocking or allowing, depending on a voltage applied between the second supply terminal 232 and the ground terminal 234.

[0045] Circuit 220 comprises a first measuring device 250, which is connected between the first supply terminal 230 and the ground terminal 234. Circuit 220 also comprises a second measuring device 252, which is connected between the second supply terminal 232 and the ground terminal 234. The first measuring device 250 is configured to detect an electrical voltage and provide a positive measured value 254 representing the voltage. The second measuring device 252 is configured to detect an electrical voltage and provide a negative measured value 256 representing the voltage.

[0046] The evaluation device 222 is designed to determine, using the positive measured value 254 and the negative measured value 256, a first resistance value Rs1 for a first insulation resistance existing between the first supply terminal 230 and the ground terminal 234 and a second resistance value Rs2 for a second insulation resistance existing between the second supply terminal 232 and the ground terminal 234.

[0047] According to one embodiment, the evaluation unit 222 is configured to use the first resistance value Rs1 and the second resistance value Rs2 to provide a control signal 258 to enable a change in the supply voltage Vin towards a target value or to block the change in the supply voltage Vin towards the target value, for example, to the device 224. According to another embodiment, the evaluation unit 222 is configured to provide the control signal 258 to block the change in the supply voltage Vin towards the target value if at least one of the resistance values ​​Rs1, Rs2 falls below a threshold value.

[0048] The following Fig. Three to four circuits, described in detail below, can advantageously be used to measure the insulation resistance of cost-sensitive traction inverters. This circuit concept is particularly suitable for traction inverter systems where the DC link voltage gradually increases. In this case, the circuits described below can be used to measure leakage resistance: Fig. Figure 3 shows a circuit diagram of an exemplary embodiment of a circuit 220 of a device for determining an insulation resistance, such as those based on Fig. 2 is described.

[0049] According to one embodiment, the device 224 for providing the supply voltage Vin is designed as a voltage source. The first supply terminal 230 is connected to a positive terminal of the device 224, and the second supply terminal 232 is connected to a negative terminal of the device 224. The ground terminal 234 is, for example, connected to a chassis.

[0050] A first insulation resistor 360 connecting the first supply terminal 230 and the ground terminal 234 is shown schematically, and its first resistance value Rs1 can be determined using the device. A second insulation resistor 362 connecting the second supply terminal 232 and the ground terminal 234 is also shown schematically, and its second resistance value Rs2 can be determined using the device.

[0051] According to one embodiment, the first voltage-controlled blocking device 240 is configured as a first Zener diode and the second voltage-controlled blocking device 244 as a second Zener diode. According to another embodiment, the first blocking resistor 242 is connected between the first Zener diode and the ground terminal 234, and the second blocking resistor 246 is connected between the second Zener diode and the second supply terminal 232.

[0052] According to one embodiment, the first measuring device 250 comprises a first operational amplifier 350 connected between the first supply terminal 230 and the ground terminal 234. The first operational amplifier 350 is configured to output a preliminary positive voltage value V as the first measured value 254. HV_SENS_POSto provide. According to one embodiment, the second measuring device 252 comprises a second operational amplifier 352 connected between the second supply terminal 232 and the ground terminal 234. The second operational amplifier 352 is configured to provide a preliminary negative voltage value V at an output as the second measured value 256. HV_SENS_NEG to provide.

[0053] According to one embodiment, an input of the operational amplifier 350 of the first measuring device 250 is connected to the first supply terminal 230 via a series circuit of two resistors with resistance values ​​Rp1 and Rp2, and to the output of the operational amplifier 350 via a resistor with resistance value RfbP.

[0054] According to one embodiment, an input of the operational amplifier 352 of the second measuring device 252 is connected to the second supply terminal 232 via a series circuit of two resistors with resistance values ​​Rn1 and Rn2 and to the output of the operational amplifier 352 via a resistor with resistance value RfbN.

[0055] Suitable operational amplifiers 350, 352 or a so-called dual operational amplifier can be used for the measuring devices 250, 252.

[0056] According to one embodiment, the preliminary positive voltage value V HV_SENS_POS and the preliminary negative voltage value V HV_SENS_NEG used by the evaluation unit to determine a positive voltage value VPsns and a negative voltage value VNsns and to determine the first resistance value Rs1 and the second resistance value Rs2.

[0057] Thus, circuit 220 is according to the one in Fig. The embodiment shown in Figure 3 is implemented using Zener diodes to calculate Rs1 and Rs2.

[0058] Fig. Figure 4 shows a circuit diagram of an exemplary embodiment of a circuit 220 of a device for determining an insulation resistance, such as those used, for example, in Fig. 2 is described.

[0059] According to one embodiment, circuit 220 corresponds to the one based on Fig. 3 described circuit, with the difference that the measuring devices 250, 252 do not include an operational amplifier but each includes a voltage divider.

[0060] According to one embodiment, the first measuring device 250 comprises a first measuring voltage divider connected between the first supply terminal 230 and the ground terminal 234. The first measuring voltage divider consists of a series connection of two measuring resistors 450, 451 with measuring resistance values ​​Rp1 and Rp2. At a connection point of the two measuring resistors 450, 451 of the first measuring voltage divider, a positive voltage value Vpos, also referred to as VPsns, is provided as the first measured value 254.

[0061] According to one embodiment, the second measuring device 252 comprises a second measuring voltage divider connected between the second supply terminal 232 and the ground terminal 234. The second measuring voltage divider consists of a series connection of two measuring resistors 452, 453 with resistance values ​​Rn1 and Rn2. At a connection point of the two measuring resistors 452, 453 of the second measuring voltage divider, a negative voltage value Vneg, also referred to as VNsns, is provided as the second measured value 256.

[0062] According to one embodiment, the positive voltage value Vpos and the negative voltage value Vneg are used by the evaluation device as the voltage values ​​VPsns, VNsns to determine the first resistance value Rs1 and the second resistance value Rs2.

[0063] Fig. Figure 5 shows a circuit diagram of an exemplary embodiment of a circuit 220 of a device for determining an insulation resistance, such as those based on Fig. 2 is described.

[0064] According to one embodiment, circuit 220 corresponds to the one based on Fig. 3 described circuit, with the difference that the voltage-controlled blocking devices 240, 244 do not include a Zener diode but input voltage-controlled switches 540, 544.

[0065] According to one embodiment, the first voltage-controlled locking device 240 comprises the first switch 540. A first control input of the first switch 540 is connected to a junction of two resistors of a first voltage divider 541. The first voltage divider 541 comprises a first resistor with resistance value Rcp1 and a second resistor with resistance value Rcp2. The series connection of the first and second resistors of the first voltage divider 541 is connected between the first supply voltage terminal 230 and the ground terminal 234. A second control input of the first switch 540 is connected to the first supply voltage terminal 230.

[0066] According to one embodiment, the second voltage-controlled locking device 244 comprises the second switch 544. A first control input of the second switch 544 is connected to a junction of two resistors of a second voltage divider 545. The second voltage divider 545 comprises a first resistor with resistance value Rcn1 and a second resistor with resistance value Rcn2. The series connection of the first and second resistors of the second voltage divider 545 is connected between the second supply voltage terminal 232 and the ground terminal 234. A second control input of the second switch 544 is connected to the second supply voltage terminal 232.

[0067] Thus, circuit 220 is according to the one in Fig. The embodiment shown in Figure 5 is implemented using the input voltage-controlled switches 540, 544 for calculating Rs1 and Rs2.

[0068] Fig. Figure 6 shows a schematic representation of an exemplary embodiment of the time course of a supply voltage Vin, as described in the preceding figures. Time is plotted on the abscissa and voltage on the ordinate. At time t0, the supply voltage Vin has a value V0, for example, 0 volts. Starting from time t0, the supply voltage Vin increases within a first phase 601 extending to time t1 until a first voltage value; starting from time t1, within a second phase 602a, 602b extending to time t2 until a second voltage value; and starting from time t2, within a third phase 603 extending to time t3 until a final value V_final is reached.

[0069] The first phase 601 is also referred to as phase 1.0, the first second phase 602a also as phase 2.1, the second second phase 602b also as phase 2.2 and the third phase 603 also as phase 3.0.

[0070] According to one embodiment, the supply voltage Vin gradually increases during a switch-on process within phases 601, 602a, 602b, 603. Optionally, the supply voltage Vin gradually decreases during a switch-off process.

[0071] According to one embodiment, the supply voltage Vin is located in a low-voltage area (LV) within the first phase 601 and in a high-voltage area (HV) within the third phase 603. Phases 601, 602a, and 602b represent a safe zone. According to another embodiment, detection of Rs1 and Rs2 takes place within the second phase 602a and 602b. Optionally, a distinction is made between a first second phase 602a and a second second phase 602b.

[0072] According to one embodiment, the evaluation device described with reference to the preceding figures is designed to determine the first resistance value Rs1 and the second resistance value Rs2 using a positive voltage value VPsns_p1 and a negative voltage value VNsns_p1 assigned to the first phase 601, as well as a further positive voltage value VPsns_p2 and a further negative voltage value VNsns_p2 assigned to one of the further phases 602a, 602b, 603. In this embodiment, phases 601, 602a, 602b, 603 represent different voltage intervals of the supply voltage Vin.

[0073] According to one embodiment, the evaluation device is designed to determine the presence of the first phase 601 if a positive threshold voltage VP_CHsns determined using the positive voltage value VPsns is less than the magnitude of a first breakdown voltage Vz1 of the first voltage-controlled blocking device and a negative threshold voltage VN_CHsns determined using the negative voltage value VNsns is less than the magnitude of a second breakdown voltage Vz2 of the second voltage-controlled blocking device.

[0074] According to one embodiment, the evaluation device is designed to determine the presence of a first second phase 602a if the positive threshold voltage VP_CHsns is greater than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is less than the magnitude of the second breakdown voltage Vz2.

[0075] According to one embodiment, the evaluation device is designed to determine the presence of a second second phase 602b when the positive threshold voltage VP_CHsns is less than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is greater than the magnitude of the second breakdown voltage Vz2.

[0076] According to one embodiment, the evaluation device is designed to determine the presence of a third phase when the positive threshold voltage VP_CHsns is greater than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is greater than the magnitude of the second breakdown voltage Vz2.

[0077] According to one embodiment, the evaluation device is designed to determine the first resistance value Rs1 and the second resistance value Rs2 using a first set resistance value Rz1_sel for the first blocking resistance, a first set voltage value Vz1_sel for the first breakdown voltage Vz1, a second set resistance value Rz2_sel for the second blocking resistance and a second set voltage value Vz2_sel for the second breakdown voltage Vz1.

[0078] In this process, when the first second phase 602a is present, the first set resistance value Rz1_sel is set to a first real resistance value Rz1 of the first blocking resistor, the first set voltage value Vz1_sel is set to the first breakdown voltage Vz1, the second set resistance value Rz2_sel is set to a predetermined first value, and the second set voltage value Vz2_sel is set to zero.

[0079] When the second phase 602b is present, the first set resistance value Rz1_sel is set to a predetermined first value, the first set voltage value Vz1_sel is set to zero, the second set resistance value Rz2_sel is set to a second real resistance value Rz2 of the second blocking resistor, and the second set voltage value Vz2_sel is set to the second breakdown voltage Vz1.

[0080] When the third phase 603 is present, the first set resistance value Rz1_sel is set to the first real resistance value Rz1, the first set voltage value Vz1_sel to the first breakdown voltage Vz1, the second set resistance value Rz2_sel to the second real resistance value Rz2 and the second set voltage value Vz2_sel to the second breakdown voltage Vz1.

[0081] In Fig. Figure 6 shows an embodiment for an input voltage and the phases 601, 602a, 602b, 603, also referred to as measuring zones. The calculation of Rs1 and Rs2 can be completed before the end of the safe zone, i.e., before the end of the second phase 602a, 602b, and a further increase to the high-voltage zone of the third phase 603 is, according to one embodiment, only possible if the resistances are within safety limits.

[0082] Vin is the supply voltage, which increases from V0 to V_final.

[0083] The following will be the in Fig. The circuit shown in section 3 is used to predict Rs1 and Rs2. For this purpose, HV_SENS_POS and HV_SENS_NEG are measured, for example, using an analog-to-digital converter.

[0084] The following describes an exemplary implementation of a method for calculating Rs1 and Rs2. VPsns=VrefP∗(Rp1+Rp2+RfbPRp1+Rp2)−VHV_SENS_POS VNsns=VrefN∗(Rn1+Rn2+RfbNRn1+Rn2)−VHV_SENS_NEG VP_CHsns=(VPsns_P1RfbP)∗(Rp1+Rp2) VN_CHsns=(VNsns_P1RfbN)∗(Rn1+Rn2) Vin=(VPCHsns−VNCHsns)

[0085] Fig. Figure 7 shows a representation of a sequence based on Fig. 6 different phases 601, 602a, 602b, 603 described of the change in the supply voltage Vin according to an exemplary embodiment.

[0086] The starting point is the state Vin = V0. The endpoint, after passing through the first phase 601 and at least one of the further phases 602a, 602b, 603, is the state Vin = V_final, i.e. the target value of the supply voltage Vin.

[0087] Thus, phase transitions are represented when Vin increases from V0 to V_final.

[0088] Depending on the values ​​of Rs1 and Rs2, each of the paths mentioned above can be taken by the recorded values.

[0089] The following is an example implementation based on Fig. 7 described in more detail.

[0090] The first phase 601 is always present, and the measured values ​​at the outputs are recorded and stored in this phase 601.

[0091] The second phases 602a, 602b are intermediate phases in which either Vp_CHsns or V_n_CHsns is larger than Vz1 or Vz2 respectively.

[0092] The transition to the third phase 603 depends on the insulation resistance values. Vin can rise to V_final with or without reaching the third phase 603.

[0093] The recorded and stored values ​​from the first phase 601 are used to calculate the values ​​of Rs1 and Rs2, along with values ​​from one of the second phases 602a, 602b or the third phase 603.

[0094] The transition from one phase 601, 602a, 602b to the next is determined by observing the values ​​of Vp_CHsns and Vn_CHsns.

[0095] The selection of values ​​for Vz1, Vz2, Rz1 and Rz2 is based on the description for Fig. 6 is specified. A resistance value of 1000 MOhm means an open circuit or infinite resistance.

[0096] The input voltage can always be calculated independently of the operating phase using the formula: Vin:=(VP_CHsns−VN_CHsns)

[0097] If data from two (not necessarily consecutive) phases 601, 602a, 602b, 603 are collected, the evaluation of Rs1 and Rs2 can be carried out as follows. M1cal=(VPsns_P1VNsns_P1) PHASE−1 DATA(must sense and store) M2cal=(VPsns_P2VNsns_P2)PHASE−2 DATA(can be sensed and selected from Phase 2.1,2.2, 3.0) K1cal=Vz1−(Rz1Rz2)∗(Vz2) H1cal=(Vsp2∗(Rz1Rz2)+K1cal)(Vsp2−K1cal)∗(M2calM1cal) H0cal=(Vsp2∗Rz1∗(1−M2calM1cal))(Vsp2−K1cal)∗(M2calM1cal) Rsncal=(−H0cal∗Rp2∗(Rn1+Rn2))(M1cal∗(Rp1+Rp2)∗Rn2+H1cal∗Rp2∗(Rn1+Rn2)) Rspcal=((−H0cal∗Rp2∗(Rn1+Rn2))∗H1cal(M1cal∗(Rp1+Rp2)∗Rn2+H1cal∗Rp2∗(Rn1+Rn2)))+H0cal Rs1cal=(Rspcal∗(Rn1+Rn2)(Rn1+Rn2)−Rsncal) Calculated Rs1 Rs2cal=(Rsncal∗(Rn1+Rn2)(Rn1+Rn2)−Rsncal) Calculated Rs2

[0098] This represents M1cal or V. Psns_P1 and V Nsns_P1 Data from the first phase 601 is there, which is sensed and stored.

[0099] In this context, M2ca and V represent Psns_P2 and V Nsns_P2 Data from one of the further phases 602a, 602b, 603da, which are sensed and stored

[0100] Rs1cal represents a calculated value for Rs1

[0101] Rs2cal represents a calculated value for Rs2

[0102] By calculating the values ​​of Rs1 and Rs2 within the safe range (before Vin reaches the HV level), a decision can be made as to whether the voltage is ramped up to V_final or whether it is switched off for testing. According to one embodiment, the third phase 603 starts at 250V.

[0103] This circuit is able to evaluate Rs1 and Rs2 even if their values ​​are the same. This is achieved by selecting Rz1≠Rz2.

[0104] Rs1 and Rs2 are evaluated in one step, without delay.

[0105] The same calculations can be used for the in Fig. The circuit variant shown in step 4 can be used, with the only change being that the values ​​of VPsns and VNsns directly match the measured values ​​and RfbP = Rp2 and RfbN = Rn2.

[0106] The same calculation can be used for the in Fig. The circuit shown in section 5 can be used, except that Vz1 and Vz2 are replaced by 0V and the phases are identified by the switch-on voltages instead of the values ​​of Vz1 and Vz2.

[0107] The same technique can also be used in ramp-down situations (active or passive discharges).

[0108] The described approach is based on a circuit and a technique for calculating the insulation leakage resistances according to an exemplary embodiment, for the HV supply of the chassis under all start-up and shutdown conditions.

[0109] By maintaining resistance values ​​in the early stages of Vin (within the safe range), failures due to breakdowns at high voltages can be prevented and user safety ensured.

[0110] The technology is inexpensive to implement and is automatic, requiring no special control strategy.

[0111] The ability to derive exact Rs1 and Rs2 values ​​is limited only by the tolerances of the components used.

[0112] According to one embodiment, no FETs or relays are used as in conventional leakage current measuring devices, and therefore no drivers or PWM generators are used either.

[0113] Since the resistance values ​​are already known in the early stages of the high-voltage supply, the decision to continue ramping up or shutting down can be made by the software to ensure the operator's safety.

[0114] The described approach is economical and can be implemented in cost-effective systems.

[0115] Advantageously, relays and control circuits that switch a known resistance on and off in the circuit can be omitted. By eliminating switches and their drivers and control circuits, costs can be kept low, making the system suitable for cost-effective battery systems.

[0116] The described approach represents a cost-effective way to calculate the insulation resistance with comparable accuracy and to ensure the safety of the user or operator.

[0117] Advantageously, this eliminates the need for switches, their drivers, and pulse generators.

[0118] The insulation leakage resistances can be measured at each start (and stop), providing the possibility to either start up or stop the DC power supply.

[0119] The integrated circuit on which the circuit is based is inexpensive and robust. For example, only a controller with an ADC pin is needed to calculate the leakage resistances.

[0120] It can also calculate insulation leakage resistances if they are nearly equal.

[0121] For example, Zener diodes are used instead of FETs or relays. Careful selection of circuit values ​​is possible. Leakage resistances can be calculated long before the supply voltage reaches its maximum value. This makes it possible to prevent failures and ensure operator safety in high-voltage battery systems.

[0122] Fig. Figure 8 shows a flowchart of an exemplary embodiment of a method for determining the insulation resistance of a power converter. The method can be implemented, for example, using a device as described with reference to the preceding figures.

[0123] The method comprises at least one step 801 of determining a first resistance value Rs1 for a first insulation resistance existing between the first supply terminal and the ground terminal and a second resistance value Rs2 for a second insulation resistance existing between the second supply terminal and the ground terminal using the positive measured value V HV_SENS_POS , VPsns and the negative measured value V HV_SENS_NEG , VNsns.

[0124] Optionally, the procedure includes a step 803 in which a control signal is provided to control a change in the supply voltage Vin using the first resistance value Rs1 and the second resistance value Rs2.

[0125] Optionally, the procedure includes a step 805 in which, depending on the design of the device's circuit, the positive measured value and the negative measured value are either expressed as positive voltage value VPsns and negative voltage value VNsns or as a preliminary positive voltage value V HV_SENS_POS and preliminary negative voltage value V HV_SENS_NEG be recorded and made available.

[0126] Optionally, in step 801 of the determination process, the phase of the supply voltage Vin is first determined. According to one embodiment, the information about the respective phase is used in step 801 to set the variables or parameters used to determine the resistance values ​​Rs1 and Rs2 to suitable values, if necessary.

[0127] Fig. Figure 9 shows a circuit diagram of an exemplary embodiment based on Fig. The circuit 220 described in section 3 has specific values ​​for the individual circuit elements. A value of 1 MOhm is assumed for the first insulation resistance 360 ​​and a value of 25 MOhm for the second insulation resistance 362.

[0128] Fig. Figure 10 shows simulation results for the based on Fig. Circuit 9 is shown. The diagram depicts voltage waveforms for the voltages V(VP_CHsns, VN_CHsns) 1001, V(vp_chsns) 1002, V(vn_chsns) 1003, V(hv_sens_neg) 1004, and V(hv_sens_pos) 1005 over time. A division into the first phase 601 and the third phase 603 is also shown.

[0129] For example, for the first phase 601, the following applies at time 2.7277687ms: VHV_SENS_POS_P1=−25.58008mVVHV_SENS_NEG_P1=228.36363mV

[0130] For example, for the third phase 603, the following applies at time 986.90671 ms: VHV_SENS_POS_P3=−1.1917314VVHV_SENS_NEG_P3=+859.05158V

[0131] The calculation of the insulation resistance values ​​is as follows: VHV_SENS_POS_P1=−25.580008mV VHV_SENS_POS_P3=−1.1917314mV VHV_SENS_NEG_P1=0.22836263mV VHV_SENS_NEG_P3=0.85905158mV VrefP=0V VrefN=0V VPsns_1=VrefP∗(Rp1+Rp2+RfbP(Rp1+Rp2))−VHV_SENS_POS_1=0.02558V VNsns_P1=VrefN∗(Rn1+Rn2+RfbN(Rn1+Rn2))−VHV_SENS_NEG_P1=−0.228363V VPsns_P2=VrefP∗(Rp1+Rp2+RfbP(Rp1+Rp2))−VHV_SENS_POS_P3=1.191730V VNsns_P2=VrefN∗(Rn1+Rn2+RfbN(Rn1+Rn2))−VHV_SENS_NEG_P3=−0.859052V VP_CHsns_P1=VPsns_P1RfbP∗(Rp1+Rp2)=6.165V VP_CHsns_P2=VPsns_P2RfbP∗(Rp1+Rp2)=287.207V VN_CHsns_P1=VNsns_P1RfbN∗(Rn1+Rn2)=−55.035V VN_CHsns_P2=VNsns_P2RfbN∗(Rn1+Rn2)=−207.031V Vin_P1=(VP_CHsns_P1−VN_CHsns_P1)=61.2V Vin_P2=(VP_CHsns_P2−VN_CHsns_P2)=494.239V Rz1=0.1MΩ Rz2=0.05MΩ Vz1=97.57V Rz1=97.57V Vsp2=Vin_P2 M1cal=(VPsns_P1VNsns_P1)=−0.112 PHASE−1 (must be sensed and stored) M2cal=(VPsns_P2VNsns_P2)=−1.387 PHASE−2 (can be sensed and stored from phase 2.1, 2.2, 3.0) K1cal=Vz1−(Rz1Rz2)∗(Vz2)=−97.57V H1cal=(Vsp2∗(Rz1Rz2)+K1cal)(Vsp2−K1cal)∗(M2calM1cal)=0.122 H0cal=(Vsp2∗Rz1∗(M2calM1cal))(Vsp2−K1cal)∗(M2calM1cal)=−7.677∗104Ω Rsncal=(−H0cal∗Rp2∗(Rn1+Rn2))(M1cal∗(Rp1+Rp2)∗Rn2+H1cal∗Rp2∗(Rn1+Rn2))=8.048∗106Ω Rspcal=((−H0cal∗Rp2∗(Rn1+Rn2))(M1cal∗(Rp1+Rp2)∗Rn2+H1cal∗Rp2∗(Rn1+Rn2)))+H0cal =9.015∗105Ω Rs1cal=(Rspcal∗(Rn1+Rn2)(Rn1+Rn2)−Rsncal) Calculated Rs1 Rs2cal=(Rsncal∗(Rn1+Rn2)(Rn1+Rn2)−Rsncal) Calculated Rs2

[0132] For Rs1 = 1MΩ & Rs2 = 25MΩ, Rs1cal = 0.9744 MΩ & Rs2cal = 24.23 MΩ can be calculated.

[0133] Fig. Figure 11 shows a circuit diagram of an exemplary embodiment based on Fig. The circuit 220 described in section 3 has specific values ​​for the individual circuit elements. A value of 0.01 MOhm is assumed for the first insulation resistance 360 ​​and a value of 10 MOhm for the second insulation resistance 362.

[0134] Fig. Figure 12 shows simulation results for the calculation based on Fig. Circuit 9 is shown. The diagram depicts voltage waveforms for the voltages V(VP_CHsns, VN_CHsns) 1001, V(vp_chsns) 1002, V(vn_chsns) 1003, V(hv_sens_pos) 1004, and V(hv_sens_neg) 1005 over time. A breakdown into the first phase 601, the second phase 602b, and the third phase 603 is also shown.

[0135] For example, for the first phase 601, the following applies at time 20.338983ms: VHV_SENS_POS_P1=−4.7807095mVVHV_SENS_NEG_P1=281.31514mV

[0136] For example, for the second phase 602b, the following applies at time 254.23729ms: VHV_SENS_POS_P2=−211.88126mVVHV_SENS_NEG_P2=501.248767mV

[0137] The calculation of the insulation resistance values ​​is as follows: VHV_SENS_POS_P1=−4.7807095mV VHV_SENS_POS_P2=−211.99126mV VHV_SENS_NEG_P1=281.31514mV VHV_SENS_NEG_P3=501.24867mV VrefP=0V VrefN=0V VPsns_P1=VrefP∗(Rp1+Rp2+RfbP(Rp1+Rp2))−VHV_SENS_POS_P1=0.004781V VNsns_P1=VrefN∗(Rn1+Rn2+RfbN(Rn1+Rn2))−VHV_SENS_NEG_P1=−0.281315V VPsns_P2=VrefP∗(Rp1+Rp2+RfbP(Rp1+Rp2))−VHV_SENS_POS_P3=0.211881V VNsns_P2=VrefN∗(Rn1+Rn2+RfbN(Rn1+Rn2))−VHV_SENS_NEG_P3=−0.501249V VP_CHsns_P1=VPsns_P1RfbP∗(Rp1+Rp2)=1.152V VP_CHsns_P1=VPsns_P2RfbP∗(Rp1+Rp2)=51.063V VN_CHsns_P1=VNsns_P1RfbN∗(Rn1+Rn2)=−67.797V VN_CHsns_P2=VNsns_P2RfbN∗(Rn1+Rn2)=−120.801V Vin_P1=(VP_CHsns_P1−VN_CHsns_P1)=68.949V Vin_P2=(VP_CHsns_P2−VN_CHsns_P2)=171.864V Rz1=1000MΩ Rz2=0.05MΩ Vz1=0V Rz1=96.046254V Vsp2=Vin_P2 M1cal=(VPsns_P1VNsns_P1)=−0.112 PHASE−1 Data (must be sensed and stored) M2cal=(VPsns_P2VNsns_P2)=−0.423 PHASE−2 Data (can be sensed and stored from phase 2.1, 2.2, 3.0) K1cal=Vz1−(Rz1Rz2)∗(Vz2)=−1.921∗106V H1cal=(Vsp2∗(Rz1Rz2)+K1cal)(Vsp2−K1cal)∗(M2calM1cal)=0.032 H0cal=(Vsp2∗Rz1+(1−M2calM1cal))(Vsp2−K1cal)∗(M2calM1cal)=−8.586∗104Ω Rsncal=(−H0cal∗Rp2∗(Rn1+Rn2))(M1cal∗(Rp1+Rp2)∗Rn2+H1cal∗Rp2∗(Rn1+Rn2))=5.826∗106Ω Rspcal=((−H0cal∗Rp2∗(Rn1+Rn2))(M1cal∗(Rp1+Rp2)∗Rn2+H1cal∗Rp2∗(Rn1+Rn2)))+H0cal =9.9∗104Ω Rs1cal=(Rspcal∗(Rn1+Rn2)(Rn1+Rn2)−Rsncal)=9.982∗104Ω calculated value for¨Rs1 Rs2cal=(Rsncal∗(Rn1+Rn2)(Rn1+Rn2)−Rsncal)=1.128∗107Ω calculated value for¨Rs2

[0138] Therefore, for Rs1 = 0.1MΩ & Rs2 = 10MΩ, the following can be calculated: Rs1cal = 0.09982 MΩ & Rs2cal = 11.28 MΩ, within the end of the safe zone (Vin < 250V).

[0139] This example shows the derivation of Rs1 and Rs2 before the third phase 603 is reached.

[0140] If Vin>250V is considered the HV_ZONE, Rs1 and Rs2 are known before this zone is reached.

[0141] The necessary measures can be taken to either increase the Vin voltage or shut down the device to ensure safety.

[0142] The third phase 603 begins at approximately 250 V. Rs1 and Rs2 can also be derived in the third 603. Reference sign 100 vehicles 104 electric machine 106 Gearbox unit 108 power converters 110 Energy supply facility 120 Device 220 circuit 222 Evaluation unit 224 Facility 224 230 first supply connection 232 second supply connection 234 Ground connection 240 first voltage-controlled locking device 242 first blocking resistor 244 second voltage-controlled locking device 246 second blocking resistor 250 first measuring device 252 second measuring device 254 positive measured value 256 negative measured value 258 Control signal 350 first operational amplifier 352 second operational amplifier 360 first insulation resistance 362 second insulation resistance 450 Measuring resistance of the first measuring voltage divider 451 Measuring resistor of the first measuring voltage divider 452 Measuring resistor of the second measuring voltage divider 453 Measuring resistor of the second measuring voltage divider 540 first switch 542 first voltage divider 544 second switch 545 second switch 601 first phase 602a first second phase 602b second second phase 603 third phase 801st step of determining Step 803 of deployment Step 805 of capturing and providing 1001 Voltage V(VP_CHsns, VN_CHsns) 1002 Voltage V(vp_chsns) 1003 Voltage V(vn_chsns) 1004 Voltage V(hv_sens_neg) 1005 Voltage V(hv_sens_pos)

Claims

[1] Device (120) for determining an insulation resistance for a power converter (108), in particular a traction converter for a vehicle (100), wherein the device (120) comprises the following features: a first supply terminal (230) for applying a first potential of a supply voltage Vin and a second supply terminal (232) for applying a second potential of the supply voltage Vin; a ground connection (234); a first voltage-controlled blocking device (240) connected in series with a first blocking resistor (242) between the first supply terminal (230) and the ground terminal (234) and a second voltage-controlled blocking device (244) connected in series with a second blocking resistor (246) between the second supply terminal (232) and the ground terminal (234); a first measuring device (250) which is connected between the first supply terminal (230) and the ground terminal (234) and is designed to measure a positive measured value (254) V HV_SENS_POS , VPsns to provide and a second measuring device (252) which is connected and configured between the second supply terminal (232) and the ground terminal (234) to obtain a negative measured value (256) V HV_SENS_NEG , provide VNsns; and an evaluation device (222) which is configured to use the positive measured value (254) V HV_SENS_POS , VPsns and the negative measured value (256) V HV_SENS_NEG , VNsns to determine a first resistance value Rs1 for a first insulation resistance (360) existing between the first supply terminal (230) and the ground terminal (234) and a second resistance value Rs2 for a second insulation resistance (362) existing between the second supply terminal (232) and the ground terminal (234). [2] Device (120) according to claim 1, wherein the evaluation device (222) is configured to provide a control signal (258) using the first resistance value Rs1 and the second resistance value Rs2 to enable a change in the supply voltage Vin towards a target value or to block the change in the supply voltage Vin towards the target value. [3] Device (120) according to one of the preceding claims, wherein the first measuring device (250) is configured to provide the positive measured value (254) as a positive voltage value VPsns and the second measuring device (252) is configured to provide the negative measured value (256) as a negative voltage value VNsns, and wherein the evaluation device (222) is configured to determine the first resistance value Rs1 and the second resistance value Rs2 using the positive voltage value VPsns and the negative voltage value VNsns. [4] Device (120) according to one of claims 1 to 2, wherein the first measuring device (250) is configured to measure the positive measured value (254) as a preliminary positive voltage value V HV_SENS_POS to provide and the second measuring device (252) is designed to measure the negative measured value (256) as a preliminary negative voltage value V HV_SENS_NEG to provide, and wherein the evaluation device (222) is configured to provide a positive voltage value VPsns using the preliminary positive voltage value V HV_SENS_POS and a negative voltage value VNsns using the preliminary negative voltage value V HV_SENS_NEG to determine and to determine the first resistance value Rs1 and the second resistance value Rs2 using the positive voltage value VPsns and the negative voltage value VNsns. [5] Device (120) according to one of claims 3 or 4, wherein the evaluation device (222) is configured to determine the first resistance value Rs1 and the second resistance value Rs2 using a positive voltage value VPsns_p1 and a negative voltage value VNsns_p1 associated with a first phase (601) and a further positive voltage value VPsns_p2 and a further negative voltage value VNsns_p2 associated with a further phase (602a, 602b, 603), wherein the phase (601) represents a voltage interval of the supply voltage Vin and the further phase (602a, 602b, 603) represents a further voltage interval of the supply voltage Vin. [6] Device (120) according to claim 5, wherein the evaluation device (222) is configured to determine the presence of the first phase (601) when a positive threshold voltage VP_CHsns determined using the positive voltage value VPsns is less than the magnitude of a first breakdown voltage Vz1 of the first voltage-controlled blocking device (240) and a negative threshold voltage VN_CHsns determined using the negative voltage value VNsns is less than the magnitude of a second breakdown voltage Vz2 of the second voltage-controlled blocking device (244), and wherein the evaluation device (222) is configured to determine the presence of a first second phase (602a) when the positive threshold voltage VP_CHsns is greater than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is less than the magnitude of the second breakdown voltage Vz2, and wherein the evaluation device (222) is trainedto determine the presence of a second phase (602b) when the positive threshold voltage VP_CHsns is less than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is greater than the magnitude of the second breakdown voltage Vz2, and wherein the evaluation device (222) is configured to determine the presence of a third phase (603) when the positive threshold voltage VP_CHsns is greater than the magnitude of the first breakdown voltage Vz1 and the negative threshold voltage VN_CHsns is greater than the magnitude of the second breakdown voltage Vz2. [7] Device (120) according to claim 6, wherein the evaluation device (222) is configured to determine the first resistance value Rs1 and the second resistance value Rs2 using a first set resistance value Rz1_sel for the first blocking resistor (242), a first set voltage value Vz1_sel for the first breakdown voltage Vz1, a second set resistance value Rz2_sel for the second blocking resistor (246) and a second set voltage value Vz2_sel for the second breakdown voltage Vz1, wherein - when the first second phase (602a) is present, the first set resistance value Rz1_sel is set to a first real resistance value Rz1 of the first blocking resistor (242), the first set voltage value Vz1_sel is set to the first breakdown voltage Vz1, the second set resistance value Rz2_sel is set to a predetermined first value and the second set voltage value Vz2_sel is set to zero, - when the second second phase (602b) is present, the first set resistance value Rz1_sel is set to a predetermined first value, the first set voltage value Vz1_sel is set to zero, the second set resistance value Rz2_sel is set to a second real resistance value Rz2 of the second blocking resistor (246), and the second set voltage value Vz2_sel is set to the second breakdown voltage Vz1, and - when the third phase (603) is present, the first set resistance value Rz1_sel is set to the first real resistance value Rz1, the first set voltage value Vz1_sel to the first breakdown voltage Vz1, the second set resistance value Rz2_sel to the second real resistance value Rz2, and the second set voltage value Vz2_sel to the second breakdown voltage Vz1. [8] Device (120) according to one of the preceding claims, wherein the first voltage-controlled blocking device (240) comprises a first Zener diode and the second voltage-controlled blocking device (244) comprises a second Zener diode. [9] Device (120) according to any one of claims 1 to 7, wherein the first voltage-controlled locking device (240) comprises a first switch (540) and a first voltage divider (541) connected between the first supply terminal (230) and the ground terminal (234) for providing a first switching signal for switching the first switch (540), and wherein the second voltage-controlled locking device (244) comprises a second switch (544) and a second voltage divider (545) connected between the second supply terminal (232) and the ground terminal (234) for providing a second switching signal for switching the second switch (544). [10] Device (120) according to claim 3, wherein the first measuring device (250) comprises a first measuring voltage divider (450, 451) connected between the first supply terminal (230) and the ground terminal (234) for detecting the positive voltage value VPsns and wherein the second measuring device (252) comprises a second measuring voltage divider (452, 453) connected between the second supply terminal (232) and the ground terminal (234) for detecting the negative voltage value VNsns. [11] Device (120) according to claim 4, wherein the first measuring device (250) includes a first operational amplifier (350) connected between the first supply terminal (230) and the ground terminal (234) for detecting the preliminary positive voltage value V HV_SENS_POScomprising and wherein the second measuring device (252) includes a second operational amplifier (352) connected between the second supply terminal (232) and the ground terminal (234) for detecting the preliminary negative voltage value V HV_SENS_NEG includes. [12] Power converter (108), in particular inverter, with a device (120), characterized by that the device (120) is designed according to one of the preceding claims. [13] Electric axle drive for a motor vehicle comprising at least one electric machine (104), a transmission device (106) and a power converter (108), characterized by , that the power converter (108) is configured according to claim 12. [14] Motor vehicle comprising an electric axle drive according to claim 13 and / or a power converter (108) according to claim 12 and / or a device (120) according to any one of claims 1 to 11. [15] Method for determining an insulation resistance for a power converter (108), in particular a traction converter for a vehicle (100), using a circuit which - a first supply terminal (230) for applying a first potential of a supply voltage Vin and a second supply terminal (232) for applying a second potential of the supply voltage Vin; a ground terminal (234), - a first voltage-controlled blocking device (240) connected in series with a first blocking resistor (242) between the first supply terminal (230) and the ground terminal (234) and a second voltage-controlled blocking device (244) connected in series with a second blocking resistor (246) between the second supply terminal (232) and the ground terminal (234), and - a first measuring device (250) which is connected between the first supply terminal (230) and the ground terminal (234) and is designed to measure a positive measured value (254) V HV_SENS_POS , VPsns and has a second measuring device (252) which is connected between the second supply terminal (232) and the ground terminal (234) and is configured to provide a negative measured value (256) V HV_SENS_NEG , provide VNsns, and the procedure includes the following step: Determining a first resistance value Rs1 for a first insulation resistance (360) existing between the first supply terminal (230) and the ground terminal (234) and a second resistance value Rs2 for a second insulation resistance (362) existing between the second supply terminal (232) and the ground terminal (234) using the positive measured value (254) V HV_SENS_POS , VPsns and the negative measured value (256) V HV_SENS_NEG, VNsns.

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