WO2024033001A1

WO2024033001A1 - Method for discharging middle switches of a 3-level inverter

Info

Publication number: WO2024033001A1
Application number: PCT/EP2023/069324
Authority: WO
Inventors: Florian Buettner; Joerg Reuss
Original assignee: Bayerische Motoren Werke Aktiengesellschaft
Priority date: 2022-08-09
Filing date: 2023-07-12
Publication date: 2024-02-15
Also published as: DE102022119970A1

Abstract

The invention relates to a method for operating a 3-level inverter (1) which has an intermediate circuit (2) with three connections and at least three switch sections (3a, 3b, 3c) which are connected to the intermediate circuit (2) and each of which comprises a phase tap (u, v, w). Each switch section (3a, 3b, 3c) has three switch devices, wherein in order to modulate an output voltage (V_a) which is specific to the working point, a switch pattern (SM) is determined for the switch devices (S1, S2, S3), said switch pattern being used by the switch devices (S1, S2, S3) to connect the phase tap (u, v, w) of each switch section (3a, 3b, 3c) to a respective connection of the connections (DC+, DC-, N) of the intermediate circuit (2), thereby producing a voltage vector (v0₁, v0₂, v0₃, v1p, v1n, v2p, v2n). In order to reduce the conduction losses of middle switch devices (S3), the switch pattern (SM) is provided in a conduction loss-reducing variant (SMa*, SMb*) in which at least one voltage vector (v0₂, v1p, v1n, v2p, v2n) of the switch pattern (SM), said voltage vector being produced by a switch state with the participation of at least one middle switch device (S3), is at least partly replaced by two voltage vectors (v0₁, v0₃, v3, v5) which are produced by switch states without the participation of the middle switch devices (S3).

Description

Method for relieving the midpoint switches of a 3-level inverter

The invention relates to a method for operating a 3-level inverter, which has an intermediate circuit with three connections in the form of a high-side connection, a low-side connection and a midpoint connection as well as at least three switching sections each connected to the intermediate circuit a phase tap for electrically connecting to one phase of an electric drive machine. Each switching section has three switching devices in the form of a high-side switching device connected to the high-side connection, a low-side switching device connected to the low-side connection and a midpoint switching device connected to the midpoint connection. To modulate an operating point-specific output voltage, a switching pattern is determined for the switching devices, through which the switching devices are converted into different switching states and thereby connect the phase tap of the respective switching section to one of the connections of the intermediate circuit, generating a voltage vector. The invention also relates to a control device, a power module and a motor vehicle.

In this case, interest is focused on 3-level inverters or three-stage inverters for electrically powered motor vehicles, i.e. electric or hybrid vehicles. Such 3-level inverters are connected between an electrical energy storage, for example a traction battery, and an electric drive machine of the motor vehicle and serve to convert a direct voltage provided by the electrical energy storage into a multi-phase alternating voltage for phases of the electric drive machine. Also, the 3-level inverter can be used as a power factor correction filter for a 3-phase charger.

Inverters usually have three half-bridges connected in parallel and an intermediate circuit connected to the half-bridges. Each half bridge has two switching devices, a first switching device being designed as a high-side switching device and being connected to a high-side connection of the intermediate circuit, and a second switching device being a low-side switching device. Side switching device is designed and is connected to a low-side connection of the intermediate circuit. In addition to the half bridges, 3-level inverters have three third switching devices, which are designed as midpoint switching devices and are each electrically connected to a tap between the first and second switching devices of a half bridge and to a midpoint connection of the intermediate circuit. Such a 3-level inverter can provide three voltage levels for the phases of the electrical machine per switching section, which consists of a half bridge and a midpoint switching device, and thus has, in addition to the eight switching states of a conventional 2-level inverter, 19 further switching states for modulating a operating point-specific output voltage. Using these 27 switching states, a desired sinusoidal shape of the output voltage with a particularly low harmonic component can be generated, thereby reducing losses in the electrical machine. In addition, the 3-level inverter has particularly low switching losses.

To reduce the costs of the 3-level inverter, for example, the quality and quantity of midpoint switches of the midpoint switching devices can be reduced. This reduction in the center point switches increases the conduction losses at certain operating points of the 3-level inverter. These transmission losses reduce the efficiency of the system due to the thermal boundary condition and can also lead to an overload of the midpoint switches.

It is the object of the present invention to provide a solution for reducing average conduction losses of midpoint switches of a 3-level inverter for a motor vehicle that occur over a modulation period.

This object is achieved according to the invention by a method, a control device, a power electronics module and a motor vehicle with the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

A method according to the invention is used to operate a 3-level inverter. The 3-level inverter has an intermediate circuit with three connections in the form of a high-side connection, a low-side connection and a midpoint connection. In addition, the 3-level inverter has at least three switching sections connected to the intermediate circuit, each with a phase tap for electrical connection to each one phase of an electric drive machine. Each switching section has three switching devices in the form of a high-side switching device connected to the high-side connection, a low-side switching device connected to the low-side connection and a midpoint switching device connected to the midpoint connection. To modulate an operating point-specific output voltage, a switching pattern is determined for the switching devices, through which the switching devices are converted into different switching states and thereby connect the phase tap of the respective switching section to one of the connections of the intermediate circuit, generating a voltage vector.

To reduce forward losses of the midpoint switching devices, the switching pattern is determined in a forward loss reducing variant, in which at least one voltage vector of the switching pattern, which is generated by a switching state involving at least one midpoint switching device, is at least partially formed by two voltage vectors, which are generated by switching states without the involvement of the midpoint switching devices , is replaced.

The invention also includes a control device which is designed to carry out a method according to the invention, as well as a power electronics module with a 3-level inverter and a control device according to the invention. A motor vehicle according to the invention comprises an electrical energy storage device, an electric machine and a power electronics module according to the invention, wherein the 3-level inverter is connected on the input side to the electrical energy storage device and on the output side to phases of a stator of the electric machine. The 3-level inverter is designed to convert the DC voltage provided by the electrical energy storage, which is present as an input voltage at the intermediate circuit of the 3-level inverter, into a multi-phase alternating voltage and to provide it as an output voltage for the phases of the electrical machine.

The 3-level inverter has the intermediate circuit on the input side, which in particular has at least one series connection of at least two capacitors. The switching sections or switching bridges each have the high-side switching device with at least one high-side switch, the low-side switching device with at least one low-side switch and the midpoint switching device with at least one midpoint switch. The high-side switching device and the low-side switching device of a switching section are connected to form a half bridge. Each switching section has a phase tap, which is connected to the associated phase electrical machine is connected. The connections of the series connection of capacitors, which form the high-side connection and the low-side connection of the intermediate circuit, are connected to poles of the electrical energy storage and to the half-bridges of the switching sections. Between the capacitors of the at least one series circuit, the midpoint connection, or midpoint for short, is provided, which is connected to the midpoint switching devices of the switching sections. The half bridges each form a vertical bridge branch of the respective switching section and the midpoint switching devices form a horizontal bridge branch of the respective switching section. The high-side switches and the low-side switches can be designed, for example, as IGBTs or power MOSFETs. To provide a bidirectional blocking capability, the midpoint switching devices can each have two midpoint switches connected in anti-series or each have one bidirectional midpoint switch. The midpoint switches can also be designed as IGBTs or power MOSFETs.

Due to the three switching devices per switching bridge, the 3-level inverter has 27 switching states with three switching bridges, each switching state generating a voltage vector that can be represented as a space vector in a vector diagram. With a closed high-side switching device of a switching section, the phase tap of this switching section is electrically connected to the high-side connection and a high-side potential is thus applied to the associated phase. With a closed low-side switching device of a switching section, the phase tap of this switching section is electrically connected to the low-side connection and a low-side potential is thus applied to the associated phase. With a closed midpoint switching device of a switching section, the phase tap of this switching section is electrically connected to the midpoint connection and thus a midpoint potential is applied to the associated phase.

For example, three switching states are created in which either all high-side switches are closed and thus all phase taps and phases are connected to the high-side connection of the intermediate circuit, or all low-side switches are closed and thus all phase taps and phases are connected are connected to the low-side connection of the intermediate circuit, or all midpoint switches are closed and thus all phase taps and phases are connected to the midpoint connection of the intermediate circuit, zero voltage vectors, which are represented as zero voltage space vectors in the space vector diagram. The zero voltage space vectors can thus be generated redundantly. Six further switching states, which do not involve the midpoint switching devices and thus the midpoint switches, generate six voltage vectors, which are represented as long, outer voltage space vectors in the space vector diagram and form corner points of an outer hexagon. These six long, outer voltage space vectors correspond to the basic voltage space vectors of a 2-level inverter and are also referred to below as basic voltage space vectors. Six further switching states involve the midpoint switching devices and generate six further voltage vectors, which are depicted as middle, outer voltage space vectors in the space vector diagram and lie on the side edges of the outer hexagon between two long, outer voltage space vectors.

Twelve further switching states, which also involve the midpoint switching devices, generate twelve short, internal voltage space vectors, with two switching states each providing two identical voltage space vectors, i.e. voltage space vectors with the same length and the same phase angle. This means that each of the short, inner voltage space vectors can be generated redundantly. The short, inner stress space vectors span an inner hexagon, with two redundant stress space vectors each forming a corner point of the inner hexagon. The mutually redundant voltage space vectors have an opposite, complementary effect on a current in the center connection of the intermediate circuit.

The outer hexagon is divided into six triangular sectors, with corner points of each sector formed by the zero voltage space vectors and two adjacent long, outer voltage space vectors. Each sector is in turn divided into four triangular segments, with two redundant voltage space vectors located at at least one corner point of each segment. In order to modulate any operating point-specific output voltage using the voltage vectors, it is determined in which sector and in which segment of the sector the operating point-specific output voltage space vector representing the output voltage lies. This operating point-specific output voltage space vector can then be generated by pulse width modulation of the voltage space vector spanning this segment. For this purpose, a switching pattern is determined in which a sequence and a duration of the segment-specific voltage space vectors used for modulation are defined. When modulating the output voltage, voltage vectors are also used in the switching pattern, which are generated by switching states involving the midpoint switching devices and in which the phase tap of at least one switching section is connected to the midpoint connection of the intermediate circuit. In the event that the midpoint switches of these midpoint switching devices are provided in a lower quality than the switches of the high-side switching device and the low-side switching device, for example for cost reasons, these have high transmission losses in certain operating ranges. These operating ranges are characterized, for example, by a modulation level and/or a modulation index and/or a modulation level and/or a phase current and/or a temperature of the midpoint switching devices. The modulation level of the 3-level inverter describes the ratio of the current output voltage to the maximum possible output voltage that can be provided by the 3-level inverter. In order to reduce these forward losses, the forward loss-reducing variant of the switching pattern is determined and preferably provided whenever the forward loss-increasing operating region of the 3-level inverter is present. Outside this operating range that increases the forward loss, the voltage vectors of the switching pattern can, for example, be alternately connected in such a way that they are loaded evenly over the modulation period.

In the transmission loss-reducing variant of the switching pattern, the involvement of the midpoint switching devices in the switching states is reduced. For this purpose, at least one voltage space vector, in particular one of the zero voltage space vectors and/or one of the inner, short voltage space vectors, is replaced by two other voltage space vectors. At low modulation levels, for example below 0.6, and at high phase currents, depending on the modulation index, for example, the zero voltage space vector which is only generated by the midpoint switching devices is at least partially replaced by the voltage space vector which is only generated with the participation of the high-side switching devices. and/or be replaced by the voltage space vector, which is only generated with the participation of the low-side switching devices.

At certain modulation levels, in particular at modulation levels around 0.6 and high phase currents, one of the redundant, inner, shorter voltage space vectors is replaced by two equivalent voltage space vectors adjacent in the space vector diagram, i.e. a basic voltage space vector and a zero voltage space vector, by These equivalent voltage space vectors are provided alternately and with equal weighting over time. This means the midpoint switches can be easily relieved if necessary.

Provision can also be made for a time weighting of the redundant voltage vectors within the switching pattern to be determined in such a way that a deviation of a midpoint voltage is reduced. This embodiment is based on the knowledge that switching states involving the midpoint switching devices cause a current load in the midpoint connection, which, if not compensated for over the modulation period, can cause an undesirable deviation in the midpoint voltage. This deviation can be achieved via the time weighting of the redundant voltage vectors in the switching pattern and in its forward loss-reducing variant. In the event that two voltage vector pairs with redundant voltage vectors are involved in modulating the output voltage, the voltage vector pair is primarily used for midpoint balancing in which the redundant voltage vector, which is weighted higher in time, has a smaller number of switching states with midpoint switch involvement. This means that one can be used at the same time Reduction of the midpoint voltage change and the load on the midpoint switching devices can be achieved.

The embodiments presented with reference to the method according to the invention and their advantages apply accordingly to the control device according to the invention, to the power electronics module according to the invention and to the motor vehicle according to the invention.

Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and/or shown in the figures alone can be used not only in the combination specified in each case, but also in other combinations or on their own.

The invention will now be explained in more detail using a preferred exemplary embodiment and with reference to the drawings. Show it: 1 is a circuit diagram of an embodiment of a 3-level inverter;

2 shows a representation of a vector diagram of the 3-level inverter;

Fig. 3 is a representation of a switching pattern for modulating a

output voltage;

4 shows a representation of time components of different voltage vectors within the switching pattern; and

Fig. 5 shows a representation of switching patterns that reduce transmission losses.

Variants for modulating an output voltage of the 3-level inverter.

In the figures, identical and functionally identical elements are provided with the same reference numerals.

Fig. 1 shows a 3-level inverter 1 for an electrified motor vehicle. The 3-level inverter 1 has an intermediate circuit 2 on the input side, which here has three intermediate circuit branches 2a, 2b, 2c, each with a series connection of two capacitors C1, C2. A high-side connection DC+ and a low-side connection DC- of the intermediate circuit 2 are connected to poles of an electrical energy storage device of the motor vehicle, which provides the intermediate circuit 2 with a direct voltage DC. Half the direct voltage DC/2 is present at each capacitor C1, C2. The 3-level inverter 1 also has three switching sections 3a, 3b, 3c, which are each electrically connected to one of the intermediate circuit branches 2a, 2b, 2c. However, it can also be provided that the intermediate circuit 2 has only one intermediate circuit branch with two series-connected capacitors C1, C2, to which the switching sections 3a, 3b, 3c are connected. Each switching section 3a, 3b, 3c has a phase tap u, v, w, which is connected to a phase Phu, Phv, Phw of an electric drive machine of the motor vehicle.

Each switching section has three switching devices S1, S2, S3, which can each have at least one switch designed as a semiconductor switch, for example IGBTs. The switching devices S1 and S2 are connected to a half bridge HB of the respective switching section 3a, 3b, 3c. The first switching devices S1 are high-side switching devices and are connected to the high-side connection DC+ of the Intermediate circuit 2, which is connected to a positive pole of the electrical energy storage, and connected to a tap A of the respective half bridge HB. The second switching devices S2 are low-side switching devices and are connected to the tap of the respective half bridge HB and to the low-side connection DC- of the intermediate circuit 2, which is connected to a negative pole of the electrical energy storage. The third switching devices S3 are midpoint switching devices and are connected to the tap and to a midpoint connection N of the respective intermediate circuit branch 2a, 2b, 2c between the two capacitors C1, C2. The midpoint switching devices S3 each have two midpoint switches S3a, S3b connected in anti-series.

The 3-level inverter 1 can assume 27 switching states, by means of which a desired, operating point-specific output voltage can be modulated for application to the phases Phu, Phv, Phw. Each switching state generates a voltage vector, which can be represented in a space vector diagram 4 shown in FIG. 2 with the axes a, ß. In the space vector diagram 4, the different switching states (u, v, w) are shown at discrete points with u, v, w = 0, 1, 2, where u indicates which of the switching devices S1, S2, S3 is closed in the first switching section 3a , v indicates which of the switching devices S1, S2, S3 is closed in the second switching section 3b, and w indicates which of the switching devices S1, S2, S3 is closed in the third switching section 3c. “0” means that the respective low-side switching device S2 is closed and thus connects the respective phase tap u, v, w to the low-side connection DC-. “1” means that the respective midpoint switching device S3 is closed and thus connects the respective phase tap u, v, w to the midpoint connection N. “2” means that the respective high-side switching device S1 is closed and thus connects the respective phase tap u, v, w to the high-side connection DC+. The discrete points mark an arrowhead of a voltage space vector generated by the respective switching state, which has a specific length and a specific phase angle. It is already clear that switching states exist that generate identical voltage vectors. For example, the switching states “221” and “110” produce identical voltage vectors. The switching states “000”, “111”, “222” also generate identical voltage vectors, namely a zero voltage vector vOi, VO2, VO3.

The space vector diagram is divided into six sectors K1, K2, K3, K4, K5, K6, where each sector K1, ..., K6 is divided into four segments Q1, Q2, Q3, Q4 (here only for the first sector K1 shown) is divided. If a specific, operating point-specific output voltage, for example the output voltage vector Va shown in FIG. 2, is now to be modulated, it is first determined in which sector K1, ..., K6 and in which segment Q1, ..., Q4 of the respective sector K1 , ... , K6 the respective output voltage vector V _a lies. For example, the output voltage vector V _a in the first sector K1 lies in the first segment Q1 and can therefore be generated by those voltage vectors vOi, generated by switching state “000”, VO2, generated by switching state “111”, VO3, generated by switching state “222”, v2p are modulated or approximated by switching state “221”, v2n, generated by switching state “110”, v1p, generated by switching state “211”, and v1n, generated by switching state “100”, which form corner points of the first segment Q1 and thus the generating output voltage vector V _a .

In the case of low control levels of the 3-level inverter 1, in particular if the control level falls below a predetermined threshold value, for example 0.6, the inner short voltage vectors v1 p, v1 n, v2p, v2n and the zero voltage vectors vOi , VO2, VO3 are placed alternately within a switching pattern in order to achieve an even load on the switching devices. For example, the switching pattern SM shown in FIG. 3 can be specified. 4 shows the total time durations dO of the zero voltage vectors vOi, VO2, VO3, d1 of the voltage vectors v1p and v1n and d2 of the voltage vectors v2p and v2n within the switching pattern SM. The individual durations of the zero voltage vectors vOi, VO2, VO3 within the total duration dO can be chosen to be the same length. However, depending on the modulation index and the phase current, a portion of the zero voltage vector VO2 can be reduced and divided between the other two zero voltage vectors vOi, VO3.

In particular, the voltage vectors v1 p, v1n, v2p, v2n influence a midpoint voltage at the midpoint connection N of the intermediate circuit 2, since these voltage vectors vOi, v1p, v1 n, v2p, v2n are generated with the participation of at least one midpoint switching device S3 and thus at least one of the phase taps u, v, w is electrically connected to the midpoint connection N. The more phase taps u, v, w are connected to the midpoint connection N per switching state, i.e. the more midpoint switching devices S3 are involved in a switching state, the greater the undesirable influence on the midpoint voltage. Therefore, in sector K1, either the voltage vector v1 n can be weighted proportionally higher than the voltage vector v1 p or the voltage vector v2n can be weighted higher than that Voltage vector v2p. Since the voltage vector v1n is only connected to the midpoint connection N via a phase tap u during generation, while the voltage vector v2n is connected to the midpoint connection N via the two phase taps u, v, the balancing of the midpoint voltage to relieve the midpoint switching devices S3 is proportional higher weighting of the voltage vector v1 n is carried out.

At high modulation levels, for example at modulation levels around 0.6 and high phase currents, the midpoint switching devices S3 in particular have high forward losses. Therefore, the time periods d1 and d2 of the redundant voltage vectors v1 p, v1 n and v2p, v2n are reduced at least by the time periods d1 _re d and d2 _re d, respectively, so that the voltage vectors v1p, v1n and v2p, v2n only for the Periods d1* or d2* occur in the switching pattern. In order to achieve this time duration reduction d1 _re d or d2red, a forward loss reducing variant SMa* (for d1>d2) or SMb* (for d2>d1) of the switching pattern SM is determined. The forward loss reducing variants SMa*, SMb* are shown in FIG. 5 for two consecutive modulation periods P1, P2. For d1>d2, the vectors v1 p, v1 n in the SMa* variant are replaced by a configurable proportion by the adjacent voltage vectors vOi and v3 or VO3 and v3. For d2>d1, the vectors v2p, v2n in the SMb* variant are replaced by a configurable proportion by the adjacent voltage vectors vOi and v5 or VO3 and v5. These voltage vectors vOi, VO3, v3 and v5 do not involve the midpoint switching devices S3, but can represent the voltage vectors v1 p, v1 n or v2p, v2n lying between them in the space vector diagram. The time weighting can be reduced, especially of that voltage vector v2n, v1p, whose switching state has the largest proportion of midpoint switching devices S3. In addition, the zero vector vOi can be set in the first modulation period P1 and the zero vector VO3 can be set in the second modulation period P2. The load is thus distributed evenly between the high-side switching device S1 and the low-side switching device S2.

Claims

Claims Method for operating a 3-level inverter (1), which has an intermediate circuit (2) with three connections in the form of a high-side connection (DC+), a low-side connection (DC-) and a midpoint connection ( N) and at least three switching sections (3a, 3b, 3c) connected to the intermediate circuit (2), each with a phase tap (u, v, w) for electrical connection to a respective phase (Phu Phv, Phw) of an electric drive machine, wherein each switching section (3a, 3b, 3c) has three switching devices in the form of a high-side switching device (S1) connected to the high-side connection (DC+) and one connected to the low-side connection (DC-). Low-side switching device (S2) and a midpoint switching device (S3) connected to the midpoint connection (N), wherein a switching pattern (SM) is determined for the switching devices (S1, S2, S3) in order to modulate an operating point-specific output voltage (V _a ). , through which the switching devices (S1, S2 S3) are converted into different switching states and thereby the phase tap (u, v, w) of the respective switching section (3a, 3b, 3c) generating a voltage vector (vOi, vÜ2, vOs, v1 p , v1n, v2p, v2n) each with one of the connections (DC+, DC-, N) of the intermediate circuit (2), characterized in that in order to reduce forward losses of the midpoint switching devices (S3), the switching pattern (SM) is in a forward loss-reducing variant ( SMa*, SMb*) is specified, in which at least one voltage vector (vÜ2, v1p, v1 n, v2p, v2n) of the switching pattern (SM), which is generated by a switching state involving at least one midpoint switching device (S3), at least partially by two voltage vectors (vOi, vOs, v3, v5), which are generated by switching states without the participation of the midpoint switching devices (S3), is replaced. Method according to claim 1, characterized in that the forward-reducing variant (SMa*, SMb*) of the switching pattern (SM) depends on a modulation index and / or a modulation level and / or a phase current and / or a temperature of the midpoint switching devices (S3) is provided. Method according to claim 2, characterized in that, depending on the modulation index and the phase current for the forward-reducing variant (SMa*, SMb*) of the switching pattern (SM), a zero voltage vector (VO2), which is caused by a switching state involving the midpoint switching devices (S3) is generated, is at least partially replaced by zero voltage vectors (vOi, VO3), which are generated by switching states without the participation of the midpoint switching devices (S3). Method according to claim 2 or 3, characterized in that, depending on the control level and the phase current for the forward loss-reducing variant (SMa*, SMb*) of the switching pattern (SM), at least one of two voltage vectors (v1p, v1 n, v2p, v2n) , which are generated redundantly via different switching states involving the midpoint switching devices (S3), at least partially replaced by a zero voltage vector (vOi, VO3) and a basic voltage vector (v3, v5) adjacent to the redundant voltage vector (v1p, v1n, v2p, v2n). is, whereby the zero voltage vector (vOi, VO3) and the basic voltage vector (v3, v5) are generated without the participation of the midpoint switching devices (S3). Method according to claim 4, characterized in that at least that one of the redundant voltage vectors (v1p, v2n) whose switching state has the highest proportion of midpoint switching devices (S3) is at least partially determined by the zero voltage vector (vOi, VO3) and the basic voltage vector (v3, v5). is replaced. Method according to one of the preceding claims, characterized in that a temporal weighting of voltage vectors (v1p, v1 n, v2p, v2n), which are generated redundantly via different switching states of the switching devices (S1, S2, S3), within the switching pattern (SM) is determined so that one Deviation of a midpoint voltage is reduced over a modulation period. Method according to claim 6, characterized in that in the case of two voltage vector pairs each with two redundant voltage vectors (v1p, v1n; v2p, v2n), the redundant voltage vector (v2n) of that voltage vector pair when reducing the deviation of the midpoint voltage to reduce the forward losses of the midpoint switching devices (S3 ) is weighted higher in time, the switching state of which has a smaller proportion of midpoint switching devices (S3) involved. Control device for a power electronics module of a motor vehicle, which is designed to carry out a method according to one of the preceding claims. Power electronics module for a motor vehicle with:

- a 3-level inverter (1), which has an intermediate circuit (2) with three connections in the form of a high-side connection (DC+), a low-side connection (DC-) and a midpoint connection (N) as well at least three switching sections (3a, 3b, 3c) connected to the intermediate circuit (2), each with a phase tap (u, v, w) for electrical connection to a respective phase (Phu, Phv, Phw) of an electric drive machine, each Switching section (3a, 3b, 3c) each has three switching devices in the form of a high-side switching device (S1) connected to the high-side connection (DC+), a low-side switching device (S1) connected to the low-side connection (DC-). Side switching device (S2) and a midpoint switching device (S3) connected to the midpoint connection (N), and

- a control device according to claim 8. Motor vehicle with an electrical energy storage, an electric drive machine and a power electronics module according to claim 9, wherein the 3-level inverter (1) is connected on the input side to the electrical energy storage and on the output side with phases (Phu, Phv, Phw). electric drive machine is connected.