Method, circuit assembly and motor vehicle for determining the current flowing through a switching element

Abstract

The invention relates to a method for determining an electrical current (I S1 -I S6 ) flowing through at least one switching element (S1-S6) of an electrical circuit assembly (2) S1 -I S6 ), wherein the electrical current flows through a conductive interval of the switching element (S1-S6) when the switching element (S1-S6) is switched on, the switching element (S1-S6) is assigned a temperature measuring device (9) and a voltage measuring device (10), the temperature measuring device (9) measures a temperature of the switching element (S1-S6), the voltage measuring device (10) measures a voltage drop over the conductive interval of the switching element (S1-S6), the temperature measuring device (9) and the voltage measuring device (10) are connected to a computing device, the computing device determines a current value of the electrical current from a temperature measurement value of the temperature measuring device (9) describing a temperature of the switching element and a voltage measurement value of the voltage measuring device (10) describing a voltage over the conductive interval.

Description

Technical Field

[0001] This invention relates to a method for determining the current flowing through at least one switching element of a circuit assembly, wherein the current flows through a conduction zone / conductivity segment of the switching element when the switching element is turned on. Furthermore, this invention relates to a circuit assembly and a motor vehicle. Background Technology

[0002] Motor vehicles equipped with electric traction drive systems typically include a traction converter or drive inverter, which converts the direct current supplied by the vehicle's traction energy storage, such as a high-voltage battery, into alternating current for operating the traction motor. During traction converter operation, the phase current of the alternating current plays a crucial role because it is directly responsible for generating torque in the motor. Typically, the phase current is directly input to the motor's regulating section as a control parameter. Therefore, accurate detection of the phase current is necessary to prevent torque deviations, as these deviations can impair motor operation and, in particular, the vehicle's driving performance.

[0003] To measure phase current, particularly in traction converters, it is known to install current sensors for phase current measurement. For example, one known approach is to use a Hall effect sensor, which detects the phase current by means of changes in the magnetic field around the conductor carrying the phase current. Furthermore, it is known that the temperature of the converter's switching elements can be determined using the measured phase current, allowing for monitoring of temperature rise in the switching elements.

[0004] Patent document US 2020 / 0112245 A1 describes a three-phase converter whose operation is regulated by a control unit. The current intensity of the phase current used for regulation by the control unit is evaluated by an overheat protection device, along with the drain-source voltage of the switching element measured by the overheat protection device, to determine the temperature-dependent resistance of the switching element. The temperature derived from the resistance is compared with a limit to determine whether overheating of the switching element has occurred.

[0005] Patent document JP 2020072569 A describes a method for measuring the temperature of a semiconductor switching element based on the change in its gate voltage over time without using a temperature sensor. Here, the load current of the switching element is obtained using a current sensor. Then, the temperature of the semiconductor element is calculated from the measured and recorded gate voltage value and the measured current value.

[0006] Patent document US 2019 / 0250046 A1 describes a three-phase inverter in which the generated phase currents are measured by Hall sensors. The temperature of the semiconductor structure elements is then determined from the measured load current and the voltage change of the output voltage of the switching elements. Summary of the Invention

[0007] The object of this invention is to provide a better method for determining the current flowing through a switching element, which can be implemented, in particular, without the use of a current sensor.

[0008] In the method of the type described at the beginning, in order to achieve this objective, according to the present invention, a temperature measuring device and a voltage measuring device are assigned to the switching element, wherein the temperature measuring device measures the temperature of the switching element, and the voltage measuring device measures the voltage drop across the conduction range of the switching element, wherein the temperature measuring device and the voltage measuring device are connected to a computing device, and the computing device determines the current value from the temperature measurement value of the temperature measuring device describing the temperature of the switching element and the voltage measurement value of the voltage measuring device describing the voltage across the conduction range.

[0009] The method according to the invention has the advantage that it eliminates the need for a current sensor to measure the current flowing through the switching element in the ON state, i.e., the load current flowing through the switching element. The resistance of the conduction zone of the switching element in the ON state is obtained from the temperature of the switching element determined by means of a temperature measuring device, for example, by means of allocation rules, such as tables or calculation rules stored in a computing device. The current flowing through the switching element can be obtained from the measured temperature and resistance of the conduction zone and the voltage drop across the conduction zone measured by a voltage measuring device. Depending on the embodiment of the switching element, the conduction zone may be, for example, the collector-emitter region or the drain-source region of the switching element.

[0010] During circuit assembly operation, the switching element can, in particular, periodically switch between an on and off state, wherein the load current flowing through the conduction range in the on state is determined by this method. Here, temperature measurement is used to determine the value of the resistance of the conduction range, i.e., the channel resistance of the switching element.

[0011] Here, the resistance of the conduction zone can be considered as a shunt and used to measure the current flowing through the structural element. Since this resistance is temperature-dependent, the current value of the conduction zone of the switching element can be determined by temperature measurement and, if necessary, by considering stored distribution rules. From this current resistance value, the current flowing through the conduction zone of the switching element can be obtained by means of a voltage measurement of the voltage drop across the resistor (this voltage measurement is recorded, especially at the same time as the temperature measurement).

[0012] The method according to the invention has the advantage of avoiding high manufacturing costs when manufacturing circuit components because it eliminates the need for costly current sensors. This advantageously eliminates the need for Hall effect sensors and / or shunt measurement circuits, as well as other analysis and filtering circuits. This method is particularly advantageous in multiphase inverter circuit components, where multiple current sensors for detecting phase currents would normally be required. The structure of the circuit components is also simplified because costly and space-consuming connections between current sensors, such as busbars, are eliminated, as are the integration of connectors and current sensors.

[0013] Furthermore, eliminating these components improves the connection of the switching elements to the cooling system, as there is no longer a need to provide structural space for the largest possible contact area between at least one switching element and the heat sink. Additionally, it simplifies the assembly and mounting of the circuit components. In particular, current determination by means of temperature measurement provides greater stability and lower susceptibility to interference in environments where electromechanical compatibility (EMV) is important, compared to using Hall sensors. This is especially true in circuit components where at least one switching element operates in a clockwise manner. By eliminating the current sensor for measuring phase current, undesirable damage to current measurement caused by interference attributable to the clockwise switching operation of the switching elements can also be avoided, eliminating the need for additional filtering circuitry.

[0014] Advantageously, the cost of developing circuit components can also be reduced by using the method according to the invention, since it is not necessary to integrate the current sensor connection into the assembly of the circuit components. Furthermore, testing of different types of current sensors and calibration of the current sensors after the completion of the circuit components can be eliminated.

[0015] According to the present invention, a temperature measuring device and a voltage measuring device continuously measure temperature and voltage values, and a computing device continuously derives current values ​​from these temperature and voltage values. This has the advantage that the determination of current can also be used, for example, in the adjustment or control of circuit components.

[0016] In cyclic switching elements, temperature and voltage measurements can be obtained in particular by obtaining at least one temperature and at least one voltage measurement for each on-state of the switching element. It is also possible to obtain multiple temperature and multiple voltage measurements in a single switching state where the switching element is on.

[0017] In a preferred embodiment of the present invention, a circuit assembly is provided that has a plurality of switching elements, each having a temperature measuring device and a voltage measuring device respectively, wherein a computing device determines the current value of the current flowing through the conduction interval for each switching element.

[0018] In circuit assemblies comprising multiple switching elements, particularly those used to generate multiphase output current, each switching element can be assigned its own temperature measuring device and its own voltage measuring device, thereby allowing the temperature and voltage drop across the conduction range of each individual switching element to be obtained. A computing device can then be used to determine the current value flowing through the conduction range for each respective switching element.

[0019] According to the present invention, a circuit assembly configured as a three-phase pulse inverter may be specified, wherein a computing device determines three phase currents from current values ​​determined for at least two of the switching elements.

[0020] In a three-phase pulse inverter, in principle, it is sufficient to determine the phase current for two of the three phases, since the third phase current can usually be calculated, especially when the motor is energized. However, it is also feasible to measure the three phase currents separately, for example, at the high-side transistors of the corresponding phases.

[0021] Measurements can also be performed on all six switching elements of a three-phase pulse inverter. Advantageously, this allows for redundancy in determining the current value. This in particular improves the accuracy of the current determination, which can then be advantageously used to control and / or regulate circuit components and / or motors connected to those circuit components.

[0022] In a preferred embodiment of the invention, the current value may be determined based on the magnitude of the control voltage appearing on the switching element in the ON state. Besides temperature, the control voltage can also be used to determine the resistance, since the resistance of the conduction range can also be related to the applied control voltage, such as the gate-source voltage or the base-emitter voltage.

[0023] Therefore, slight fluctuations in the control voltage can be taken into account when determining the resistance and consequently the current within the conduction range. The functional relationship of the control voltage appearing on the switching element in the on state can also be stored in the computing device and used in determining the current value using allocation rules, such as tables or calculation rules.

[0024] According to the invention, a computing device configured to operate a drive circuit for the circuit components is used, wherein, in particular, switching elements are switched via the drive circuit based on a determined current value. This enables the direct use of current measurements to regulate the circuit components or the motor connected to them. Furthermore, the computing device configured to operate the drive circuit for the circuit components already knows the switching states of individual switching elements, thereby advantageously simplifying the overall structure for implementing the method according to the invention.

[0025] According to the present invention, the temperature measuring device and the voltage measuring device may be connected to and / or include an analog-to-digital converter, wherein the digitized temperature measurement value and the digitized voltage measurement value are transmitted to a computing device, particularly through an electrically isolated connection or an electrically isolated connection.

[0026] Analog-to-digital converters (ADCs) for temperature and / or voltage measuring devices can digitize analog parameters, such as voltage, output by the temperature and / or voltage measuring devices, and thus transmit them digitally to a computing device. For example, the temperature measuring device may include a temperature sensor connected to the ADC. The voltage measuring device may include an ADC connected to a conduction range on the input side, or an ADC configured to directly detect the voltage drop across the conduction range and output it as a digital value. Here, for example, a Sigma-Delta converter is used as the ADC.

[0027] The temperature measuring device and the voltage measuring device may each include at least one preamplifier, at least one filter, and / or at least one integrator connected upstream of the analog-to-digital converter, or connected thereto. Here, the preamplifier, filter, and integrator are particularly arranged on the analog side of the analog-to-digital converter, so that the corresponding processed measurement signals from the temperature measuring device and the voltage measuring device can be transmitted to the computing device.

[0028] Electrically isolated connections are essential, especially for computing devices that also control drive circuits. By transmitting digitized measurements from temperature and voltage measuring devices, it is advantageous to determine current values ​​and, if necessary, to achieve high immunity to interference in the operation of circuit components. For transmission via the electrically isolated connection, an analog-to-digital converter can be connected to the transmitting unit, wherein a corresponding receiving unit is provided on the computing device side, which receives the transmitted measurement values ​​and transmits them to the computing unit.

[0029] The analog-to-digital converter, along with necessary preamplifiers, filters, integrators, and / or transmitting units, can be arranged on a driver circuit board, which is connected to the computing device, particularly via a current connection. This eliminates the need for additional circuitry. Consequently, a compact structure and high stability of the circuit components are advantageously achieved.

[0030] In a preferred embodiment of the invention, a switching element may be used, integrated together with at least a portion of the assigned temperature measuring device within a power module. Here, the temperature measuring device may be at least partially disposed within the power module and assigned to a conduction range of the switching element.

[0031] In particular, it is feasible for the power module to include multiple switching elements, which, for example, form a half-bridge, wherein each of the switching elements is assigned a temperature measuring device. In this way, particularly accurate temperature determination of the conduction range of the switching elements is achieved. The temperature measuring device can be contacted and connected to a computing device, in particular, via contacts arranged on the housing of the power module.

[0032] According to the present invention, a temperature measuring device comprising a temperature-dependent resistor can be specified. Here, the resistor can be a resistor with a negative temperature coefficient (NTC resistor) or a resistor with a positive temperature coefficient (PTC resistor). This achieves robust temperature determination of the conduction range of the corresponding switching element. Furthermore, using a temperature-dependent resistor simplifies the process of integrating it into a power module including the switching element, i.e., arranging it within the housing of the power module.

[0033] According to the present invention, metal-oxide-semiconductor field-effect transistors (MOSFETs), especially those based on silicon carbide, can be used as switching elements. When the switching element is configured as a MOSFET, the conduction region is correspondingly the drain-source region of the transistor. In the on state, the resistance of the drain-source region (also referred to as R) DS,on It has a temperature-dependent resistance, which can be determined by temperature measurement, especially when the transistor's turn-on voltage or gate-source voltage is constant.

[0034] For the circuit assembly according to the invention, it is specified that the circuit assembly includes at least one switching element having a conduction range, wherein the switching element is provided with a temperature measuring device and a voltage measuring device, wherein the temperature of the switching element can be measured by the temperature measuring device, and the voltage drop across the conduction range of the switching element can be measured by the voltage measuring device, wherein the temperature measuring device and the voltage measuring device are connected to a computing device configured to perform the method according to the invention.

[0035] For a motor vehicle according to the present invention, it is specified that the motor vehicle includes circuit components according to the present invention.

[0036] The advantages and design schemes described above with reference to the method according to the invention are correspondingly applicable to the circuit components according to the invention and the electric motor vehicles according to the invention. Conversely, embodiments of the circuit components and motor vehicles are also applicable to the method according to the invention, embodiments of the circuit components are also applicable to motor vehicles, and vice versa. Attached Figure Description

[0037] Other advantages and details of the invention will become apparent from the embodiments described below and from the accompanying drawings.

[0038] The attached diagram is a schematic diagram and includes:

[0039] Figure 1 An embodiment of a motor vehicle according to the present invention is shown.

[0040] Figure 2 An embodiment of the circuit assembly according to the present invention is shown.

[0041] Figure 3 Detailed diagrams of the circuit components according to the present invention are shown, and

[0042] Figure 4 An equivalent circuit diagram of a circuit component according to the invention, used to explain an embodiment of the method according to the invention, is shown. Detailed Implementation

[0043] exist Figure 1 An embodiment of a motor vehicle 1 according to the present invention is shown. The motor vehicle 1 includes a circuit assembly 2, which is implemented as a three-phase traction inverter of the motor vehicle 1. By means of the circuit assembly 2, direct current extracted from the traction energy storage 3 of the motor vehicle 1, such as a high-voltage battery, can be converted into three-phase alternating current for running the traction motor 4 of the motor vehicle 1.

[0044] exist Figure 2 An embodiment of circuit assembly 2 is shown. Circuit assembly 2 is implemented as a three-phase pulse inverter and includes six switching elements S1-S6. Switching elements S1 and S4, S2 and S5, and S3 and S6 each form a half-bridge, wherein switching elements S1-S3 are high-side transistors and switching elements S4-S6 are correspondingly low-side transistors.

[0045] The connection points, indicated by HV+ and HV-, on the DC current side of circuit assembly 2 are connected, for example, to the traction accumulator 3 of vehicle 1. An intermediate circuit capacitor 6 is connected between these connection points. The bridge nodes of each half-bridge 5 respectively form phase terminals U, V, and W for connecting the traction motor 4. Circuit assembly 2 can convert the DC current extracted from the traction accumulator 3 into a current with phase current I. U I V and I W The three-phase alternating current is used to operate the traction motor 4. Conversely, the alternating current generated by the traction motor 4 in generator mode can also be converted into direct current to charge the traction accumulator 3.

[0046] Furthermore, circuit assembly 2 also includes a computing device 7 and a drive circuit 8, wherein the computing device 7 is configured to operate the drive circuit 8. The drive circuit 8 is used to control the voltage or gate-source voltage U. G1 -U G6 It is applied to the switching elements S1-S6. For clarity, the connection between the drive circuit 8 and the control connection of the switching elements S1-S6 is not shown.

[0047] For example, switching elements S1-S6 are implemented as silicon carbide-based MOSFETs. Each of switching elements S1-S6 includes a conduction region through which current flows when the switching element is turned on. The conduction regions of switching elements S1-S6 are drain-source regions, through which load current flows when the corresponding switching element has been switched to a conductive state by the drive circuit 8, in order to generate phase current I, especially in a clockwise operation. U I V and / or I W .

[0048] As in Figure 3 As schematically shown for the switching element S1, the switching element S1 is equipped with a temperature measuring device 9 and a voltage measuring device 10 of circuit component 2. As an equivalent circuit diagram of the switching element S1, the resistance R of the conduction range, also known as the channel resistance, obtained in the on-state of the switching element S1 is shown. DS,on The conductive range is equipped with a temperature measuring device 9, which measures the temperature of the conductive range or the junction temperature of the switching element. The temperature measuring device 9 includes a temperature-dependent resistor 11. This resistor may be implemented as an NTC resistor or a PTC resistor, for example.

[0049] The voltage measuring device 10 may be connected to or include two contacts 12 arranged on the drain-source region of the switching element S1. The temperature measuring device 9 is connected to the analog-to-digital converter 14, implemented herein as a Sigma-Delta modulator, via a preamplifier 13. Furthermore, a reference voltage source 15 is shown. The contacts 12 (through which the voltage of the conduction region, i.e., the drain-source voltage of the switching element S1, can be intercepted) are also connected to the analog-to-digital converter 14 via the preamplifier 13. In this embodiment, the amplifier 13 and the analog-to-digital converter 14 are the voltage measuring device 10.

[0050] The preamplifier 13, analog-to-digital converter 14, and reference voltage source 15 can each be implemented as part of the drive circuit 8 and arranged on a common circuit board, for example, together with other components of the drive circuit 8. The temperature measuring device 9, particularly the temperature-dependent resistor 11, is integrated with the switching element S1 in a power module 16. Here, the power module 16 may also include the switching element S4 and, consequently, the entire half-bridge 5. In this case, the temperature measuring device 9, particularly the temperature-dependent resistor 11, assigned to the switching element S4, is also integrated into the power module 16.

[0051] The digitized measurement values ​​of temperature measuring device 9 and voltage measuring device 10, transmitted via analog-to-digital converter 14, are transmitted to computing device 9 through electrical isolation connection 17. Electrical isolation connection 17 includes at least one insulator 18 and multiple transmitters 19 and receivers 20 for transmitting the digitized measurement values ​​of temperature measuring device 9 and voltage measuring device 10. Furthermore, an interface 21 is provided for connecting computing device 9 to electrical isolation connection 17 and, consequently, to temperature measuring device 9 and voltage measuring device 10.

[0052] exist Figure 3 The components shown for the switching element S1 are present in particular for each of the switching elements S1-S6 in the circuit assembly 2, and thus for the switching elements S2-S6, the temperature measuring device 9, the voltage measuring device 10, and the components 13-15 and 19-21 required for evaluating the measured values ​​and transmitting the measured values ​​to the computing device 9 are also present and arranged accordingly.

[0053] exist Figure 4 A schematic equivalent circuit diagram of circuit assembly 2 is shown to explain an embodiment of a method for determining the current flowing through at least one of the switching elements S1-S6 of circuit assembly 2. This method can be executed by a computing device 7, as shown in... Figure 3 As shown in the figure, the temperature measuring device 9 and the voltage measuring device 10 are respectively connected to the switching elements S1-S6.

[0054] The resistors R are schematically shown in the equivalent circuit diagram. DS,on,S1 -R DS,on,S6 These represent the temperature-dependent resistances of the conduction drain-source regions of switching elements S1-S6, respectively. Temperature measuring device 9 measures the temperature of each of the corresponding assigned switching elements S1-S6. Voltage measuring device 10 measures the voltage drop across the conduction regions of switching elements S1-S6 accordingly. The calculation device calculates the corresponding current I. S1 -I S6 The current value. Here, in order to obtain the current I... S1 The temperature measurement value of the temperature measuring device 9 and the voltage measurement value of the voltage measuring device 10 of the switching element S1 are used. Other load currents can be determined accordingly by the temperature measuring devices 9 and voltage measuring devices 10 of the other switching elements S2-S5.

[0055] Here, temperature measurement device 9 and voltage measurement device 10 continuously measure temperature and voltage values, while a computing device continuously derives current measurement values ​​from the temperature and voltage values. From the temperature measurement values, the computing device 7 can, for example, determine the temperature-related channel resistance R according to allocation rules stored in the computing device 7. DS,on The resistance value. For example, the allocation rule can be a calculation rule or a stored table. Additionally, it is feasible for the calculation device 7 to also consider the corresponding control voltage U. G1 -U G6 The measured value is because, especially in silicon carbide MOSFETs, the control voltage also affects the resistance R. DS,on The size has an impact.

[0056] By measuring the current I through all switching elements S1-S6 S1 -I S6 This can generate redundancy, thereby advantageously enabling higher accuracy in current measurement and / or stability of circuit components. From the determined current value I... S1 -I S6 The phase current I can be obtained from it. U I V and I W Depending on the switching state of switching element S1, the phase current is equivalent to the determined current I. S1 -I S6 At least one of the current values, so that the phase current can be calculated from the current value.

[0057] Alternatively, it is also feasible not to provide a temperature measuring device 9 and / or a voltage measuring device 10 on each of the switching elements S1-S6, and therefore not to determine a current value for each of the switching elements. For example, the current value can be determined only for the high-side transistors S1-S3. It is also feasible to determine the current value for only two of the high-side transistors S1-S3. Here, for example, when the phases U, V, W of the motor 4 are connected in a star or delta configuration, the remaining current I can be calculated from the two determined current values. U I V and I W The third current value of one of them.

[0058] Advantageously, this method eliminates the need for measuring phase current I. U I V and I W An additional current sensor is added. This allows for the more cost-effective, smaller, and more efficient manufacture of circuit assembly 2. Furthermore, the stability of circuit assembly 2 is improved because fewer components and wiring connections are required. Moreover, by integrating a portion of the measuring device and / or the electrical isolation connection 17 into the drive circuit 8, the overall structure of circuit assembly 2 is simplified. This also simplifies the assembly of circuit assembly 2 in the vehicle 1.

[0059] The drive circuit 8 may be arranged in a common housing together with the inverter consisting of three half-bridges 5. The computing device 7 may also be arranged in this housing, or the computing device may be arranged in another location and connected to the drive device 8 and the temperature measuring device 9 and voltage measuring device 10 of the switching elements S1-S6.

[0060] The computing device 9 can operate the drive circuit 8 according to the determined current value. In particular, preferably in the case of current regulation of the three-phase motor current for the traction motor 4, the computing device 9 can operate the drive circuit 8 according to the current value I. S1 -I S6 Determined phase current I U I V and I W The drive circuit 8 is operated, and consequently, the switching elements S1-S6 are also operated. For this purpose, the computing device may be connected, for example, to the rotor position sensor (not shown) of the traction motor 4 and / or to a data communication connection device (not shown), through which rotor position information and / or the torque to be adjusted can be received.

[0061] The stable and compact structure of circuit component 2 also simplifies cooling, for example, by connecting it to a cooling device (not shown) of vehicle 1. By integrating the entire measurement chain, consisting of temperature measuring device 9 and voltage measuring device 10, into drive circuit 8, the susceptibility to measurement interference can be significantly reduced. The analog-to-digital converter 14, implemented as a Sigma-Delta converter, advantageously provides a digitized output signal, thereby minimizing susceptibility to interference.

[0062] The method according to the invention can also be used in two-phase inverters or inverters designed to generate alternating current with more than three phases. Accordingly, the above-described embodiments of the circuit assembly 2 configured as a three-phase inverter also apply.

Claims

1. A method for determining the current (I) flowing through at least one switching element (S1-S6) of a circuit assembly (2). S1 -I S6 The method, in which, Current in switching element (I S1 -I S6 When switched on, current flows through the conduction range of the switching elements (S1-S6). A temperature measuring device (9) and a voltage measuring device (10) are assigned to the switching elements (S1-S6). The temperature measuring device (9) measures the temperature of the switching elements (S1-S6), while the voltage measuring device (10) measures the voltage drop across the conduction range of the switching elements (S1-S6). The temperature measuring device (9) and the voltage measuring device (10) are connected to a computing device. The computing device determines the current value from the temperature measurement value of the temperature measuring device (9) which describes the temperature of the switching elements, and the voltage measurement value of the voltage measuring device (10) which describes the voltage across the conduction range. The step of determining the current value includes: According to the control voltage (U) applied to the switching elements (S1-S6) in the on state G1 -U G6 The resistance of the switching element in the on-state is determined by the magnitude of the resistance and / or the temperature of the switching element as determined by a temperature measuring device; and The current flowing through the switching element is obtained from the measured temperature and resistance of the conduction range, as well as the voltage drop across the conduction range measured by the voltage measuring device.

2. The method according to claim 1, characterized in that, Temperature and voltage measurements are continuously taken by temperature measuring device (9) and voltage measuring device (10), and calculation device (7) continuously determines current value from these measured temperature and voltage values.

3. The method according to claim 1 or 2, characterized in that, The circuit assembly (2) is used, namely, the circuit assembly has multiple switching elements (S1-S6) each assigned a temperature measuring device (9) and a voltage measuring device (10), wherein the computing device (7) determines the current value of the current flowing through the conduction interval for each of these switching elements (S1-S6).

4. The method according to claim 3, characterized in that, Using a circuit assembly (2) configured as a three-phase pulse inverter, wherein a computing device (7) determines three phase currents (I3, I4, I5) from current values ​​determined for at least two of the switching elements (S1-S6). U I V I W ).

5. The method according to any one of the preceding claims, characterized in that, The computing device used is configured to run the drive circuit (8) of the circuit assembly (2), wherein the switching elements (S1-S6) are switched by the drive circuit (8).

6. The method according to claim 5, characterized in that... The switching elements (S1-S6) are switched according to the determined current value.

7. The method according to any one of the preceding claims, characterized in that, The temperature measuring device (9) and the voltage measuring device (10) are connected to and / or include an analog-to-digital converter (14) that transmits digitized temperature and voltage measurements to a computing device (7).

8. The method according to claim 7, characterized in that The digitized temperature measurement value and the digitized voltage measurement value are transmitted to the computing device (7) through the electrical isolation connection (17).

9. The method according to any one of the preceding claims, characterized in that, The switching elements (S1-S6) used are integrated together with at least a portion of the assigned temperature measuring device (9) in a power module (16).

10. The method according to any one of the preceding claims, characterized in that, The temperature measuring device (9) used includes a temperature-dependent resistor (11).

11. The method according to any one of the preceding claims, characterized in that, Metal-oxide-semiconductor field-effect transistors (S1-S6) are used as switching elements.

12. The method according to claim 11, characterized in that, The metal-oxide-semiconductor field-effect transistor is based on silicon carbide.

13. A circuit assembly comprising at least one switching element (S1-S6) having a conduction range, wherein, The switching elements (S1-S6) are equipped with a temperature measuring device (9) and a voltage measuring device (10). The temperature measuring device (9) can measure the temperature of the switching elements (S1-S6), and the voltage measuring device (10) can measure the voltage drop in the conduction range of the switching elements (S1-S6). The temperature measuring device (9) and the voltage measuring device (10) are connected to a computing device (7), which is configured to perform the method according to any one of claims 1 to 12.

14. A motor vehicle comprising the circuit assembly (2) according to claim 13.

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