A drive system having a converter and an inverter for powering an electric motor

Abstract

The present invention relates to a drive system, which includes a converter, in particular an AC / DC converter, and an inverter for supplying power to an electric motor. The electric motor is electrically connected to the AC voltage side terminals of the inverter, and the DC voltage side terminals of the inverter are connected to the DC voltage side terminals of the converter. A first device for detecting the voltage at the AC voltage side terminals of the converter is connected to the input of the first analog-to-digital converter of the signal electronics via a first signal line. A second device for detecting the voltage on a filter, in particular a three-phase voltage, can be connected to the input of the second analog-to-digital converter of the signal electronics via a second signal line. The signal electronics has a drive control device for the semiconductor switches of the converter. The output of the first analog-to-digital converter and the output of the second analog-to-digital converter are connected to a comparison device of the signal electronics. According to the output signal of the comparison device, a switching device of the signal electronics adjusts the operating mode of the drive control device of the semiconductor switches of the converter.

Description

Field of the Invention

[0001] The present invention relates to a drive system having a converter and an inverter for powering an electric motor. Background Art

[0002] It is known that an electric motor operating in generator mode and powered by an inverter drives electrical power to the DC voltage side terminals of the inverter.

[0003] DE 10 2006 028 103 A1 discloses an uninterrupted switching between sinusoidal and square-wave grid-side current converter operations as the closest prior art. Summary of the Invention

[0004] Therefore, the object of the present invention is to improve a drive system having an inverter and a converter for powering an electric motor, wherein higher safety can be achieved during operation.

[0005] According to the present invention, this object is achieved in a drive system according to the features given in claim 1 and a method according to the features given in claim 12 or 13.

[0006] An important feature of the present invention in terms of the drive system is that the drive system has a converter, in particular an AC / DC converter, and an inverter for powering an electric motor, which is electrically connected to the AC voltage side terminals of the inverter.

[0007] Wherein, the DC voltage side terminals of the inverter are connected to the DC voltage side terminals of the converter.

[0008] Wherein, a first device for detecting the voltage at the AC voltage side terminals of the converter, in particular three-phase voltage, in particular the voltage space vector, is connected to the input of a first analog-to-digital converter of the signal electronics device, in particular a Σ-Δ converter, by means of a first signal line.

[0009] Wherein, a second device for detecting the voltage at the filter, in particular three-phase voltage, in particular the voltage space vector, can be connected to the input of a second analog-to-digital converter of the signal electronics device, in particular a Σ-Δ converter, by means of a second signal line.

[0010] Wherein, the signal electronics device has a control device for the semiconductor switches of the converter.

[0011] Wherein, the outputs of the first analog-to-digital converter and the second analog-to-digital converter are connected to a comparison device of the signal electronics device.

[0012] According to the output signal of the comparison device, a switching device of the signal electronics device adjusts the operating mode of the control device for the semiconductor switches of the converter.

[0013] The advantage here is that it is possible to automatically recognize whether a filter is present, i.e., whether it is installed and electrically connected, so that sinusoidal operation can be performed, or whether the filter is absent, i.e., the power grid is directly connected, i.e., switched on, to the converter via a line choke, so that square-wave operation must be carried out. Because for sinusoidal feedback, a chopper choke is required in the control path, otherwise feedback synchronized with the grid voltage phase cannot be performed. However, square-wave operation does not require a chopper choke and a filter. Hard operation can be carried out on the power grid, where square-wave feedback is started in a voltage-controlled manner and ended according to the current.

[0014] The converter preferably has its own housing, which is separate from the line choke or a possible chopper choke and the filter. When the last-mentioned components are connected, the second signal line must also be connected, i.e., switched on.

[0015] The method for operating the drive system can be carried out using the drive system according to the invention, which will be explained in more detail below.

[0016] In an advantageous design, the second signal line is connected to a fixed potential, especially HIGH or LOW, by means of a resistor, especially a pull-up resistor. The advantage here is that the input of the Σ-Δ converter has a permanently fixed potential, and it is thus easy to see that the end of the second signal line is open, i.e., no device for voltage detection is arranged at the filter.

[0017] In an advantageous design, a slender intermediate circuit is arranged at the AC voltage side terminals of the converter, i.e., especially no capacitor-supported intermediate circuit is arranged.

[0018] and / or

[0019] The capacitance at the DC voltage side terminals of the converter, especially a capacitive voltage divider, especially a capacitive voltage divider consisting of non-polar capacitors, is at most 2 μF or at most 8 μF per kilowatt of inverter rated power.

[0020] The advantage here is that a slender intermediate circuit, i.e., a capacitor-free intermediate circuit, can be used. This can avoid electrolytic capacitors and the associated short service life of electrical appliances. Therefore, the low capacitance at the intermediate circuit is not even sufficient to buffer half a grid cycle.

[0021] In an advantageous design, the converter is an AC / DC converter, in particular, the converter is a regenerative rectifier / energy feedback rectifier. The advantage here is that the drive control signal of the semiconductor switch of the converter, which is pulse-width modulated by the drive control device, is sufficient to use the converter as a current regulator during feedback. In the case of sinusoidal operation, the drive control signal is generated such that the feedback current is fed back in phase synchronization with the grid voltage. The magnitude of the current is adjusted such that the voltage detected at the DC voltage side terminals of the converter is adjusted towards the theoretical value.

[0022] In an advantageous design, depending in particular on the switching state of the switching device, the operating mode is sinusoidal feedback or square-wave feedback. The advantage here is that the switching state of the switching device is determined by identifying the presence or absence of a filter. In particular, the signal electronics drives the semiconductor switches of the converter such that, in the case of square-wave feedback, the voltage at the DC voltage side terminals of the converter feeds the phase terminals of the AC voltage side of the converter whose voltage is lower than the voltage at the DC voltage side terminals of the converter for a time until the phase current detected by the current detection device of the corresponding phase terminal disappears.

[0023] Therefore, there is no chopper choke in the square-wave feedback operation. There is also no filter. Therefore, depending on the voltage, the energy from the DC voltage intermediate circuit is subsequently directly supplied to the corresponding phase, in particular to the grid choke assigned to the corresponding phase, and this supply terminates according to the current. Therefore, the square-wave operation is a hard operation at the grid, where only a grid choke is arranged between the converter and the grid.

[0024] In the case of sinusoidal feedback operation, there is a chopper choke and a filter between the converter and the grid choke, so that controlled operation can be carried out.

[0025] In an advantageous design, the comparison device compares the values of the corresponding phases of two detected voltages represented by a digital 1-bit data stream, and has a first state at its output when the deviation between the two values is below the allowed deviation, and otherwise has another state. The advantage here is that the output signal thus determines the switching state of the switching device.

[0026] In an advantageous design, according to the output signal of the comparison device, if the output signal remains constant during the shortest duration, the switching device of the signal electronics adjusts the operating mode of the drive control device of the semiconductor switches of the converter. The advantage here is that the identification of the filter can be reliably ensured.

[0027] In an advantageous design, the AC voltage side terminals of the converter are connected to the common AC power grid via a grid choke. The advantage here is that the grid choke can be implemented as three-phase, i.e., one of the inductances of the grid choke is arranged in each phase line.

[0028] In an alternative advantageous design, the AC voltage side terminals of the converter are connected to a filter via a chopper choke, and the filter is connected to a grid choke. The advantage here is that sinusoidal feedback can be achieved because the chopper choke is arranged between the converter acting as a regulator and the grid-side voltage detection device, and thus the regulated variable does not individually determine the detected variable.

[0029] In an advantageous design, the grid choke has an inductance in each phase line, and the chopper choke has an inductance in each phase line.

[0030] Wherein, the filter has a star point formed by capacitors, and each capacitor is connected to the star point with its respective first terminal and to the respective phase line with the respective other terminal.

[0031] In particular, the DC voltage side terminals of the converter feed a series circuit composed of two additional capacitors, and the connection node is electrically connected to the star point. The advantage here is that the star point can be directly or via another capacitor connected to the electrical ground terminal, i.e., PE. The filter shorts the high-frequency voltage components in the differential voltage of the phase lines. The grid filter suppresses the high-frequency voltage components coupled into the phase lines.

[0032] In an advantageous design, in the operating mode of sinusoidal feedback, the regulator adjusts the voltage value detected at the DC voltage side terminals of the converter towards the theoretical value in such a way that the drive device drives the semiconductor switches of the converter, i.e., the current is fed into, in particular, feedback to the chopper choke synchronously with the detected second voltage phase. The advantage here is that as little interference as possible is introduced into the common AC power grid by means of sinusoidal feedback.

[0033] In an advantageous design, the output signal of another comparison device of the signal electronics is related to the difference between the rotation direction of the voltage detected by the first device and the rotation direction of the voltage detected by the second device. The advantage here is that wiring errors can be identified.

[0034] An important feature in the method for operating a drive system is that the drive system has a converter with semiconductor switches, in particular an AC / DC converter, and an inverter for powering an electric motor, and the electric motor is electrically connected to the AC voltage side terminals of the inverter.

[0035] Wherein, the DC voltage side terminals of the inverter are connected to the DC voltage side terminals of the converter.

[0036] In particular, the phase line is connected to the AC voltage side terminals of the converter,

[0037] wherein the voltage at the AC voltage side terminals of the converter, in particular a three-phase voltage having three phase voltages, in particular the voltage space vector, is detected and conducted via a first signal line, in particular a multi-core signal line, to the input of a first analog-to-digital converter of the signal electronics, in particular a Σ-Δ converter,

[0038] wherein the voltage at the filter, in particular a three-phase voltage, in particular the voltage space vector, can be conducted via a second signal line, in particular a multi-core signal line, to the input of a second analog-to-digital converter of the signal electronics, in particular a Σ-Δ converter,

[0039] wherein, based on the comparison of the output signal of the first analog-to-digital converter with the output signal of the second analog-to-digital converter, the operating mode of the drive means of the semiconductor switches of the converter is adjusted,

[0040] In particular, each of the electrically insulated core wires of the second signal line is connected to a fixed potential, in particular HIGH or LOW, via a respective resistor, in particular a pull-up resistor. The advantage here is that the operating mode is set to a sinusoidal operating mode or a square-wave operating mode depending on the presence or absence of the chopper choke.

[0041] In an advantageous design, based on the comparison of the rotation direction of the voltage detected on the filter with the rotation direction of the voltage detected on the AC voltage side terminals of the converter, an error state, in particular a wiring error, is reported and / or indicated. The advantage here is that a wiring error can be identified.

[0042] In an advantageous design, the filter has a star point formed by capacitors, wherein each capacitor is connected to the star point with its respective first terminal and to the respective phase line with its respective other terminal. The advantage here is that the high-frequency differential voltage between the phase lines is suppressed and thus the detected voltage only changes relatively slowly accordingly.

[0043] In an advantageous design, the second signal line is implemented as multi-core, in particular such that the respective core wires of the second signal line conduct the respective phase voltages to the input of the second analog-to-digital converter, in particular to the respective channels of a multi-channel analog-to-digital converter. The advantage here is that a three-phase voltage can be used as the AC voltage and thus not only a single voltage but also a three-phase voltage, i.e., a three-component space vector variable, can be detected.

[0044] In an advantageous design, the first signal line is implemented as multi-core, in particular such that the respective core lines of the first signal line conduct the respective phase voltages to the input of the first analog-to-digital converter, in particular to the respective channels of a multi-channel first analog-to-digital converter. The advantage here is that three-phase voltages can be used as alternating voltages, and thus not only can individual voltages be detected, but also three-phase voltages, i.e., three-component space vector variables.

[0045] Further advantages are given by the dependent claims. The invention is not limited to the feature combinations of the claims. For a person skilled in the art, other reasonable combination possibilities of the claims and / or the features of individual claims and / or the features of the description and / or the features of the drawings can be obtained, especially from the purpose put forward and / or by comparison with the prior art. Description of the Drawings

[0046] The present invention will be described in detail below with reference to the drawings:

[0047] Figure 1 Shows a drive system according to the invention in a first operating mode with sinusoidal feedback when the electric machine 8 is operating in generator mode.

[0048] Figure 2 Shows a drive system according to the invention in a second operating mode with square-wave feedback when the electric machine 8 is operating in generator mode. Detailed Description of the Invention

[0049] As shown in the drawings, the electric machine 8, in particular a three-phase alternating current machine, is supplied by an inverter 7 having control electronics which generate pulse-width modulated drive signals for the controllable semiconductor switches of the inverter, wherein the inverter has a parallel circuit of half-bridges supplied by a direct voltage, in particular an intermediate circuit voltage. Each half-bridge is configured as a series circuit consisting of two controllable semiconductor switches, in particular MOSFET switches or IGBT switches, wherein each semiconductor switch is respectively connected in parallel with a freewheeling diode.

[0050] Thus, when the electric machine 8 is operating in motor mode, the inverter 7 can supply three-phase voltages to the electric machine 8.

[0051] When the electric machine 8 is operating in generator mode, electrical power is fed from the electric machine 8 via the inverter 7, in particular via its freewheeling diodes, into the intermediate circuit, i.e., to the DC voltage side terminals of the inverter.

[0052] A capacitor C for at least smoothing high-frequency voltage fluctuations is arranged at the DC voltage side terminals. In addition, the DC voltage side terminals of the converter 5 and the DC voltage side terminals of the inverter are connected in parallel, so that the electric power from the intermediate circuit can be transmitted from the converter 5 to the common AC power grid, which is connected to the AC voltage side terminals of the converter 5 via the grid choke 1, the filter 2 and the chopper choke 3.

[0053] The converter 5 is preferably implemented as a bidirectional AC / DC converter here. In particular, a controllable regenerative rectifier 5 is suitable for this.

[0054] The voltage is detected at the converter 5, preferably at the AC voltage side terminals of the converter 5. For this purpose, three phase voltages of the three-phase voltage on the AC voltage side terminals of the converter 5 are preferably detected and conducted in an analog manner via a multi-core first signal line to a first analog-to-digital converter, and the digital data stream with a bit width of especially 1 of the first analog-to-digital converter is conducted to the evaluation unit of the signal electronics, and the evaluation unit determines the magnitude and direction of the corresponding voltage space vector therefrom.

[0055] In addition, the voltage is detected on the filter 2. Here, three phase voltages of the three-phase voltage on the filter 2 are also preferably detected and conducted in an analog form via a multi-core second signal line to a second analog-to-digital converter, and the digital data stream with a bit width of especially 1 of the second analog-to-digital converter is conducted to the evaluation unit of the signal electronics 4, and the evaluation unit determines the magnitude and direction of the corresponding voltage space vector therefrom.

[0056] The cores of the multi-core signal lines are electrically insulated from each other and are respectively connected to the potential HIGH by means of corresponding pull-up resistors.

[0057] The difference between two voltage space vectors, especially the difference between the magnitudes of two voltage space vectors, is provided to the control electronics of the inverter 7.

[0058] The filter 2 preferably has three capacitors, where each capacitor connects its first terminal to the star point and the corresponding other terminal to the corresponding one of the phases of the three-phase voltage on the filter 2.

[0059] The filter 2 is connected to the common AC power grid via a three-phase grid choke 1.

[0060] The filter 2 is connected to the converter 5 by means of a three-phase chopper choke 3.

[0061] The star point is conductively connected to the connection node of two capacitors connected in series, especially with the same capacitance value, and the series circuit thus formed is arranged at the DC voltage side output of the converter 5, that is, in parallel with the capacitor C of the intermediate circuit.

[0062] The difference drops at the chopper choke 3. Thus, sinusoidal feedback can be achieved during generator operation.

[0063] Here, by synchronizing the current supplied from the converter 5 to the filter 2 via the chopper choke with the voltage detected across the filter 2, the intermediate circuit voltage is regulated towards the theoretical value. Therefore, the regulator determines the current, which is the regulated variable, such that the phase is equal to the phase of the voltage detected across the filter 2, especially a three-phase voltage, and the magnitude of the current is regulated by the regulator such that the intermediate circuit voltage is regulated towards the theoretical value.

[0064] The current is regulated or set by driving the controllable semiconductor switches of the converter 5 in a corresponding pulse-width modulation manner.

[0065] The current to be regulated or set is preferably provided as a theoretical value to a current regulator, and the actual value of the current is regulated towards this theoretical value by, considering the phase equality with the voltage detected across the filter 2, correspondingly regulating the pulse-width modulation ratio of the drive signal for the semiconductor switches of the converter 5 by the current regulator.

[0066] The actual value of the current can either be detected by means of a current sensor or can be determined from the difference when the inductance of the chopper choke is known.

[0067] Due to the mains filter 1, high-frequency interference is prevented from entering the public power grid. However, in particular, the filter 2 represents / presents a short circuit for high-frequency interference. This suppresses such interference.

[0068] As Figure 2 shown, when there is no chopper choke 3 and filter 2, only square-wave feedback can be performed.

[0069] Here, the intermediate circuit voltage across the capacitor C is detected, and when a threshold value is exceeded, especially a threshold value corresponding to the peak voltage of the voltage at the AC voltage side terminals of the converter 5, electrical power is conducted into the public AC power grid by opening the corresponding semiconductor switches of the converter 5. Here, the semiconductor switches whose respective phase voltages are lower than the intermediate circuit voltage are always opened.

[0070] The semiconductor switches of the converter 5 are arranged as a parallel-connected half-bridge, where this parallel circuit can be supplied by the intermediate circuit voltage. Each half-bridge consists of a series circuit of two semiconductor switches, which are each connected in parallel with a freewheeling diode. Each half-bridge is implemented as a series circuit of two semiconductor switches, and the connection node of these two semiconductor switches is connected to a corresponding one of the three phase voltages.

[0071] To suppress interference, a mains filter 1 is arranged on the input side of the converter 5.

[0072] The Δ-Σ converter is used as the second analog-to-digital converter to perform the detection of the voltage on filter 2, i.e., the external voltage. If each of the three core wires of signal line 4 has an open end, this is because there is no filter 2 and chopper choke 3 present, but rather the line choke 1 is directly connected to converter 5. Then, for each phase, a permanent status signal, especially a HIGH signal, may be present at the output of the Δ-Σ converter because the corresponding pull-up resistor connects the corresponding open core wire of the second signal line to the upper potential HIGH. If this HIGH signal exists for a longer time than the critical duration, it is concluded that the line choke 1 is directly present at converter 5 and thus the square-wave feedback is activated as the operating mode.

[0073] However, if it is determined that there is a non-zero difference between the voltage detected on filter 2 and the voltage detected on converter 5 within a minimum time period, the sine feedback is activated as the operating mode. The non-zero difference is understood here as exceeding a threshold. That is, if the value of the difference between the two voltages, especially the three-phase voltage space vectors, exceeds the threshold over the duration of the minimum time period, the sine feedback is activated as the operating mode. Because it can be concluded from the non-zero difference that there are a chopper choke 3 and a filter 2.

[0074] In addition, the rotation direction of the voltage space vector detected on filter 2 and the rotation direction of the voltage space vector detected on converter 5 are determined. If the two rotation directions are not the same, there is a wiring error. In this case, an error state is indicated.

[0075] According to the present invention, when the drive system is started or switched on, first the voltage on signal line 4 is compared with the voltage detected on converter 5, i.e., the difference is determined.

[0076] The Δ-Σ converter can also be referred to as the Σ-Δ converter.

[0077] In other embodiments according to the present invention, LOW can be used instead of HIGH.

[0078] List of reference numerals:

[0079] 1 Line choke

[0080] 2 Filter

[0081] 3 Chopper choke

[0082] 4 Signal line for transmitting the voltage signal detected at filter 2, especially externally

[0083] 5 Converter, especially an AC / DC converter, especially a regenerative rectifier

[0084] 6 Voltage detection on the converter

[0085] 7 Inverter for controlling an electronic device

[0086] 8 Electric motor, especially three-phase AC motor

[0087] C Capacitor

[0088] R Braking resistor

Claims

1. A drive system, which includes a converter and an inverter for powering an electric motor, the electric motor being electrically connected to the AC voltage side terminals of the inverter, the DC voltage side terminals of the inverter being connected to the DC voltage side terminals of the converter, a first device for detecting the voltage at the AC voltage side terminals of the converter is connected to the input of the first analog-to-digital converter of the signal electronics via a first signal line, a second device for detecting the voltage on the filter can be connected to the input of the second analog-to-digital converter of the signal electronics via a second signal line (4), Among them, the second analog-to-digital converter is implemented such that when the second signal line (4) is not connected, a zero value, zero voltage, fixed potential or negligible voltage is output at the output of the second analog-to-digital converter, the signal electronics has drive control means for the semiconductor switches of the converter, characterized in that the outputs of the first analog-to-digital converter and the second analog-to-digital converter are connected to a comparison means of the signal electronics, and according to the output signal of the comparison means, the switching means of the signal electronics adjusts the operating mode of the drive control means of the semiconductor switches of the converter.

2. The drive system according to claim 1, characterized in that, The second signal line (4) is connected to a fixed potential via a resistor.

3. The drive system according to claim 2, wherein, The resistor is a pull-down resistor or a pull-up resistor.

4. The drive system according to any one of claims 1 to 3, characterized in that, The second signal line (4) is a multi-core signal line.

5. The drive system according to any one of claims 1 to 3, characterized in that An elongated intermediate circuit is arranged at the AC voltage side terminals of the converter, and / or the capacitance at the DC voltage side terminals of the converter is at most 2 μF or at most 8 μF per kilowatt of the inverter rated power.

6. The drive system according to claim 5, wherein, The intermediate circuit is an intermediate circuit without capacitor support.

7. The drive system according to claim 5, wherein The capacitance is a capacitance voltage divider.

8. The drive system according to claim 7, wherein The capacitance voltage divider consists of non-polar capacitors.

9. The drive system according to any one of claims 1 to 3, characterized in that, The converter is an AC / DC converter.

10. The drive system according to claim 9, characterized in that, The converter is a regenerative rectifier.

11. The drive system according to any one of claims 1 to 3, characterized in that, Depending on the switching state of the switching means, the operating mode is sinusoidal feedback or square wave feedback, wherein, in the case of square wave feedback, the voltage at the DC voltage side terminals of the converter supplies power to the phase terminal at the AC voltage side terminals of the converter, the voltage of which is lower than the voltage at the DC voltage side terminals of the converter, until the phase current detected by the corresponding current detection means of the phase terminal disappears.

12. The drive system according to any one of claims 1 to 3, characterized in that, The comparison means compares the values represented by the digitized 1-bit data streams of the two detected voltages, and has a first state at its output when the deviation between the two values is lower than the allowable deviation, and otherwise has another state.

13. The drive system according to any one of claims 1 to 3, characterized in that According to the output signal of the comparison means, if the output signal remains constant during the shortest duration, the switching means of the signal electronics adjusts the operating mode of the drive control means of the semiconductor switches of the converter.

14. The drive system according to any one of claims 1 to 3, characterized in that, The AC voltage side terminals of the converter are connected to a common AC power grid via a grid choke, wherein the second signal line (4) is not connected to the input of the second analog-to-digital converter, or the AC voltage side terminals of the converter are connected to a filter connected to the grid choke via a chopper choke, wherein the second signal line (4) is connected to the input of the second analog-to-digital converter.

15. The drive system according to claim 14, characterized in that, The grid choke is a common mode choke.

16. The drive system according to any one of claims 1 to 3, characterized in that, The line choke in each phase line has an inductance, the chopper choke in each phase line has an inductance, the filter has a star point formed by the capacitors of the filter, each capacitor is connected to the star point with its respective first terminal and is connected to the corresponding phase line with the other terminal respectively, wherein, - the DC voltage side terminals of the converter are supplied by a series circuit composed of two additional capacitors, and the connection node is electrically connected to the star point, - and / or the DC voltage side terminals of the converter supply a capacitive voltage divider, and the divided voltage generated by the capacitive voltage divider is directly applied at the star point.

17. The drive system according to any one of claims 1 to 3, characterized in that In the operating mode of sinusoidal feedback, the regulator adjusts the voltage value detected at the DC voltage side terminals of the converter towards the theoretical value in the following manner: the drive device drives the semiconductor switches of the converter such that a current synchronized with the detected second voltage phase is fed into the chopper choke.

18. The drive system according to any one of claims 1 to 3, characterized in that, The output signal of another comparison device of the signal electronic device depends on the difference between the rotation direction of the voltage detected by the first device and the rotation direction of the voltage detected by the second device.

19. A method for operating a drive system according to any one of claims 1 to 18, the drive system having a converter with semiconductor switches and an inverter for supplying power to an electric motor, the electric motor being electrically connected to the AC voltage side terminals of the inverter, the DC voltage side terminals of the inverter being connected to the DC voltage side terminals of the converter, Among them, the phase lines being connected to the AC voltage side terminals of the converter, checking whether there are chopper chokes and filters connected to the AC voltage side terminals of the converter, for the purpose of checking, detecting the voltage at the AC voltage side terminals of the converter and comparing it with the voltage at the signal line terminals of the converter, the voltage at the signal line terminals being equal to the voltage of the filter when the chopper choke and the filter are connected and equal to zero voltage when the chopper choke and the filter are not connected, adjusting the operating mode of the converter according to the comparison result, the operating mode being sinusoidal feedback or square wave feedback, wherein an elongated intermediate circuit is arranged at the AC voltage side terminals of the converter, wherein, in the case of square wave feedback, the voltage at the DC voltage side terminals of the converter is supplied to the corresponding phases of the AC voltage side terminals of the converter in a voltage-controlled manner until the current flowing in the phase disappears.

20. The method according to claim 19, wherein The operating mode is the operating mode of the drive device of the semiconductor switches of the converter.

21. A method for operating a drive system according to any one of claims 1 to 18, the drive system having a converter with semiconductor switches and an inverter for supplying power to an electric motor, the electric motor being electrically connected to the AC voltage side terminals of the inverter, the DC voltage side terminals of the inverter being connected to the DC voltage side terminals of the converter, Among them, the phase lines being connected to the AC voltage side terminals of the converter, detecting the voltage at the AC voltage side terminals of the converter and conducting it to the input of the first analog-to-digital converter of the signal electronic device via the first signal line, The voltage on the filter is conducted to the input of the second analog-to-digital converter of the signal electronic device via a second signal line. The operating mode of the drive control device of the semiconductor switch of the converter is adjusted based on the comparison between the output signal of the first analog-to-digital converter and the output signal of the second analog-to-digital converter. The second analog-to-digital converter is implemented appropriately such that if no voltage is supplied to the input of the second analog-to-digital converter, the output signal of the second analog-to-digital converter is a zero voltage or a fixed potential. Each core wire of the second signal line that is electrically insulated from each other is connected to a fixed potential via a respective resistor.

22. The method according to any one of claims 19 to 21, characterized in that Based on the comparison between the rotation direction of the voltage detected on the filter and the rotation direction of the voltage detected on the AC voltage side terminals of the converter, an error state is reported and / or displayed. And / or the filter has a star point formed by capacitors, each capacitor being connected to the star point with its respective first terminal and connected to the corresponding phase line with the other terminal respectively.

23. The method according to any one of claims 19 to 21, characterized in that, The second signal line is implemented as multi-core such that the respective core wires of the second signal line conduct the respective phase voltages to the input of the second analog-to-digital converter, and / or The first signal line is implemented as multi-core such that the respective core wires of the first signal line conduct the respective phase voltages to the input of the first analog-to-digital converter.

24. The method according to claim 23, wherein The respective core wires of the second signal line conduct the respective phase voltages to the respective channels of a multi-channel analog-to-digital converter, and the respective core wires of the first signal line conduct the respective phase voltages to the respective channels of the multi-channel first analog-to-digital converter.

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