Method and device for operating electric machine in emergency mode of operation

Abstract

The invention relates to a device for providing an emergency mode of operation of an electric machine, in which the electric machine is operated in Q different phases which vary between a high-side potential and a high-side potential, Q > = 3. The device is configured to determine, for one time of a series of successive times, an angle value of an electric rotor angle of the electric machine at the respective time; and determining for each of the Q phases, based on an angle value of the electric rotor angle, whether a respective respective when in a high-side state or a low-side state. The device is further configured to generate a pulse sequence for each of the Q phases in order to operate the electric machine in an emergency mode of operation.

Description

Field of the Invention

[0001] The present invention relates to a method and a corresponding device for operating an electric machine in an emergency operating mode. Background Art

[0002] An electric machine, such as a permanent magnet synchronous machine or an electrically excited synchronous machine, can be used, for example, to drive a motor vehicle (as a traction motor). In the event of a fault, it may be necessary to cause the electric machine to operate in an emergency, and the (electrical) energy of the electric machine is reduced through the emergency operation. Exemplary emergency operating modes are active short circuit (AKS), in which the connection terminals of the electric machine are short-circuited by means of suitable switching elements, or freewheeling (FL), in which the connection terminals of the electric machine are decoupled from the energy supply device.

[0003] In FL operation, the energy of the electric machine flows into the intermediate circuit. When the high-voltage memory of the motor vehicle is separated from the intermediate circuit (for example, due to an accident or a faulty line interruption), the intermediate circuit capacitors of the intermediate circuit may be damaged due to a relatively high voltage rise. In AKS operation, a relatively high transient short-circuit current may cause damage to the electric machine (such as permanent magnet demagnetization or thermal damage to the windings and / or semiconductors).

[0004] The effects of FL operation and / or AKS operation can be solved by over-sizing the electric machine, which, however, results in increased costs, increased weight, and increased space requirements. Summary of the Invention

[0005] This document is dedicated to the following technical objective: to provide a particularly efficient and reliable emergency operating mode for an electric machine.

[0006] The task is solved by each independent claim in the independent claims. Advantageous embodiments are described in particular in the dependent claims. It should be noted that the additional features of the claims subordinate to the independent claims can form an invention that is self-contained and independent of all the features of the independent claim without the features of the independent claim or only in combination with a part of the features of the independent claim, and can be the subject of an independent claim, a divisional application, or a subsequent application. This also applies to the technical teachings described in the specification, which can form an invention independent of the features of the independent claim.

[0007] According to one aspect, a device for providing an emergency operating mode of an electric machine is described, wherein the electric machine operates with Q different phases, each of which varies between a high-side potential and a low-side potential, where Q ≥ 3, in particular Q = 3. The high-side potential can be, for example, a specific operating voltage, while the low-side potential can be ground voltage or earth voltage. Alternatively, the high-side potential can be a positive operating voltage, while the low-side potential can be a negative operating voltage. The electric machine can be a permanent magnet synchronous machine (PSM). Alternatively, the electric machine can also be a separately excited and / or electrically excited synchronous machine (FSM or SSM).

[0008] The device can be configured to detect a fault condition of the electric machine and / or of an electric drive system comprising the electric machine. In other words, the device can be configured to detect a fault condition. The fault condition can relate to the electric machine and / or to components related to the operation of the electric machine (such as relating to an inverter and / or to an electrical energy storage for storing electrical energy for the operation of the electric machine). In response to the detected fault condition, a switchover from the standard operating mode of the electric machine to the emergency operating mode of the electric machine can be caused.

[0009] The device is configured to determine (in particular for one moment in a series of successive moments) an angular value of the electrical rotor angle of the electric machine at the respective moment (for example based on sensor data of a rotor sensor).

[0010] The device is further configured to determine for each of the Q phases, based on the angular value of the electrical rotor angle: whether the respective phase is in and / or should be in (either) a high-side state or (either) a low-side state. For example, a predefined allocation unit can be used to determine for each of the Q phases whether the respective phase is in and / or should be in a high-side state or a low-side state. The allocation unit can be configured to indicate for a plurality of different (in particular for all possible) angular values of the electrical rotor angle whether the respective phase is in and / or should be in a high-side state or a low-side state.

[0011] Furthermore, the device is configured to generate a pulse sequence (for the operation of the electric machine) for each of the Q phases respectively. The pulse sequence for one phase can respectively comprise one or more pulses each having a specific pulse duration. Furthermore, the one or more pulses can succeed each other at a pulse frequency.

[0012] When the respective phase is in and / or should be in a high-side state, the pulse can have the high-side potential. This can be achieved by closing the high-side switching element of the inverter for the respective phase. On the other hand, when the phase is in and / or should be in a low-side state, the pulse can have the low-side potential. This can be achieved by closing the low-side switching element of the inverter for the respective phase.

[0013] Accordingly, a device is described which generates pulses for individual phases in emergency operation, the voltage potential of the pulses (in particular the low-side potential or the high-side potential) depending on the angular value of the electrical rotor angle. Thereby, a particularly efficient and reliable emergency operation mode can be provided.

[0014] Each pulse sequence can have an intermediate interval with a (specific) interval duration between two directly successive pulses. The sum of the interval duration and the pulse duration can correspond to the reciprocal of the pulse frequency. The device can be configured to cause idling or short-circuiting of the Q phases respectively in the intermediate interval between two pulses. Here, the Q phases can be decoupled from the high-side potential and from the low-side potential (and optionally from each other) to achieve idling of the Q phases. On the other hand, the Q phases can be coupled to each other to achieve short-circuiting of the Q phases.

[0015] By implementing idling and / or short-circuiting in the intermediate interval between successive pulses, the efficiency and reliability of the emergency operation mode can be further improved.

[0016] One or more pulses in the pulse sequence of the Q phases are preferably synchronized with each other in time (and thus occur simultaneously). Thereby, the performance of the emergency operation mode can be further improved.

[0017] The pulse sequences of the Q (in particular Q = 3) phases can be configured such that the pulse sequences for two different phases respectively have simultaneous pulses, both of which have the high-side potential or both of which have the low-side potential.

[0018] In particular, the pulse sequences of the Q (in particular Q = 3) phases can be configured such that the pulse sequences for the Q phases respectively have simultaneous pulses, in each of which two pulses respectively have the high-side potential or (alternatively) two pulses respectively have the low-side potential. For example, in the case of Q = 3 phases, the simultaneous pulses for two phases can both have the high-side potential. The simultaneous pulse for the third phase can then have the low-side potential. Alternatively, the simultaneous pulses for two phases can both have the low-side potential. The simultaneous pulse for the third phase can then have the high-side potential.

[0019] The above characteristics can apply to all pulses of the pulse sequence (in the emergency operation mode). Through this pulse synchronization, a particularly reliable emergency operation mode can be provided.

[0020] The device can be configured to determine one or more operating parameters of the electric machine at a corresponding time, where the one or more operating parameters particularly include the angular velocity of the electric machine. The pulse frequency and / or pulse duration of each pulse can be determined based on the one or more operating parameters. By adjusting the pulse frequency and / or pulse duration according to the corresponding operating state of the electric machine, the emergency operating mode can be further optimized.

[0021] For a complete cycle [0 - 2π] of the electrical rotor angle, the pulse sequences of the Q phases can each have one or more pulses. The device can be configured to determine the pulse frequency such that for a complete cycle [0 - 2π] of the electrical rotor angle, the pulse sequences of the Q phases each include 2*Q or more pulses. Thereby, a particularly reliable emergency operating mode can be provided.

[0022] The device can be configured to determine the polarity of the I q current of the electric machine in the dq coordinate system at a corresponding time. Then, the corresponding phase can be determined to be in and / or should be in the high-side state or the low-side state based on the polarity of the I q current. By considering the polarity of the current, the performance of the emergency operating mode can be further improved.

[0023] In a preferred example, the following assignment relationship between the angular value of the electrical rotor angle and the states of the respective phases is adopted. Thereby, the performance of the emergency operating mode can be further improved.

[0024] For Q = 3 and I q <0:

[0025] · The first phase u is in the high-side state when the angular value of the rotor angle is [9π / 12 - 21π / 12], and otherwise in the low-side state;

[0026] · The second phase v is in the high-side state when the angular value of the rotor angle is [0 - 5π / 12] and [17π / 12 - 2π], and otherwise in the low-side state; and / or

[0027] · The third phase w is in the high-side state when the angular value of the rotor angle is [π / 12 - 13π / 12], and otherwise in the low-side state. For Q = 3 and I q >0:

[0028] · The first phase u is in the high-side state when the angular value of the rotor angle is [π / 4 - 15π / 12], and otherwise in the low-side state;

[0029] · The second phase v is in the high-side state when the angular value of the rotor angle is [11π / 12 - 23π / 12], and otherwise in the low-side state; and / or

[0030] · The third phase w is in the high-side state when the angular value of the rotor angle is in the ranges [0 - 7π / 12] and [19π / 12 - 2π], and in the low-side state otherwise.

[0031] According to another aspect, a road motor vehicle (in particular a passenger car, a lorry, a bus or a motorcycle) is described, which comprises the device and the electric machine described herein (for example for driving the vehicle).

[0032] According to another aspect, a method for providing an emergency operating mode for an electric machine is described. The method comprises determining an angular value of the electrical rotor angle of the electric machine, and for each of the Q phases determining, based on the angular value of the electrical rotor angle: whether the respective phase is in and / or should be in a high-side state or a low-side state. Furthermore, the method comprises generating a pulse sequence for each of the Q phases, where the pulse sequence for one phase respectively comprises one or more pulses each having a pulse duration. Furthermore, the one or more pulses can succeed one another at a pulse frequency. When the respective phase is in and / or should be in a high-side state, the pulses can have a high-side potential. On the other hand, when the phase is in and / or should be in a low-side state, the pulses can have a low-side potential.

[0033] The method can be aimed at determining Q pulse sequences for the respective Q phases. Here, based on the angular value of the electrical rotor angle, it can be determined for each of the Q phases whether the respective phase should be in a high-side state or a low-side state. In other words, based on the angular value of the electrical rotor angle, it can be determined for each of the Q phases whether the pulse sequence for the respective phase should have one or more pulses with a high-side potential or (alternatively) one or more pulses with a low-side potential. Then the respective pulse sequence can be generated (by closing the respective switching elements). Thus, the pulse sequence is in the previously determined target state (i.e., the high-side state or the low-side state).

[0034] Thus, it can be determined for each phase respectively which target state the respective phase should be in. Furthermore, it can be made (by generating the respective pulse sequence) that the respective phase is in the previously determined target state. Thus, in this context, the concepts of "being in a certain state" or "being a certain state" are used interchangeably with the concepts of "should be in a certain state" or "should be a certain state".

[0035] According to another aspect, a software (SW) program is described. The SW program can be configured to run on a processor (for example on a control device of a vehicle) and thereby execute the method described herein.

[0036] According to another aspect, a storage medium is described. The storage medium can comprise an SW program which is configured to run on a processor and thereby execute the method described herein.

[0037] It should be noted that the methods, devices, and systems described in this document can be used alone or in combination with other methods, devices, and systems described in this document. In addition, various aspects of the methods, devices, and systems described in this document can be combined with each other in multiple ways. In particular, the features in the claims can be combined with each other in multiple ways. In addition, the features listed in parentheses should be understood as optional features. Description of the Drawings

[0038] The present invention will be described in more detail below with the aid of embodiments. In the figures:

[0039] Figure 1a An exemplary inverter for an electric machine is shown;

[0040] Figure 1b An example curve of the phase voltage for the standard operating mode is shown;

[0041] Figure 2a An example angular sector for the negative quadrature-axis phase current I q is shown;

[0042] Figure 2b An example angular sector for the quadrature-axis phase current I q is shown;

[0043] Figure 3 An exemplary pulse sequence for different phases of the electric machine over a complete period of the electrical rotor angle is shown;

[0044] Figure 4a An exemplary device for operating an electric machine is shown;

[0045] Figure 4b An exemplary device for a pulse sequence for determining different phases of an electric machine is shown;

[0046] Figure 5 A flowchart of an exemplary method for providing an emergency operating mode for an electric machine is shown. Detailed Description of the Invention

[0047] As described above, this document aims to provide a particularly efficient and reliable emergency operating mode for an electric machine. In this regard, Figure 1a An exemplary inverter 100 is shown, which is configured to be based on the grid voltage U DC110 (i.e., DC voltage) generates phase voltages 111 (i.e., AC voltages) for different phases or windings of the electric machine 103 (e.g., an electric machine of a vehicle). The inverter 100 (or Inverter) includes a plurality of switches or switching elements 102, 104, which in the example shown are arranged in half-bridges for each phase u, v, w respectively. The switching elements 102, 104 are controlled by the control unit 101 to generate the phase voltages 111 for the electric machine 103. It should be noted that, by means of the Clarke-Park transformation, the phase voltages 112 and / or phase currents 112 can be transformed between the uvw coordinate system and the dq coordinate system.

[0048] Figure 1b An exemplary phase voltage 111 is shown, which can be generated by the switching elements 102, 104 of the half-bridge. As can be seen from Figure 1b it, the switching elements 102, 104 are switched (i.e., opened or closed) in a specific pulse pattern to generate the (sinusoidal) AC voltage 111. For a determined (static) operating point of the electric machine 103, the pulse pattern can be pre-determined, for example, by means of an optimization method such as SOPWM, by which a specific optimization criterion (e.g., the harmonic distortion of the phase current) can be optimized (especially minimized). The pulse patterns determined for different operating points of the electric machine 103 can be stored, for example, in a look-up table (LUT). Here, each pulse pattern has a pulse pattern with a specific number of pulses for each wave or half-wave of the AC voltage to be generated. Different operating points of the electric machine 103 can include, for example, different torques to be provided and / or different rotational speeds. Operating the electric machine 103 in such a pulse pattern can be referred to as the standard operating mode.

[0049] When a fault occurs, it may be necessary to operate the electric machine 103 in an emergency operating mode to consume the energy of the electric machine 103. This can be achieved by AKS operation or by FL operation. As mentioned at the beginning, these operating methods may result in relatively high transient short-circuit currents and / or voltages.

[0050] From short-circuit simulation and no-load simulation, the following conditions can be determined to optimally suppress the transient short-circuit current and / or to optimally reduce the electrical energy flowing into the intermediate circuit of the electric machine 103 or the inverter 100 (in the dq coordinate system):

[0051]

[0052] Based on these conditions, switching patterns can be determined for different angular sectors of the electrical rotor angle, which achieve optimally suppressing the transient short-circuit current and / or optimally reducing the energy flowing into the intermediate circuit. In particular, six different angular sectors can be considered, which respectively have specific switching patterns, for example, in Table 1a (for I q<0) and Table 1b (for I q >0) are shown exemplarily in

[0053]

[0054] Table 1a

[0055]

[0056] Table 1b

[0057] The corresponding angle sectors 201 and switching patterns 205 are also shown in Figure 2a and Figure 2b the switching pattern diagram 200 of. Here, the angle sector 201 extends between two angle values 202 of the electrical rotor angle, respectively.

[0058] Each phase u, v, w can be in the state "0" (i.e., the low-side state) or "1" (i.e., the high-side state) in the switching pattern 205. Here, the state "0" means that the high-side switching element 102 for the corresponding phase is continuously open in the corresponding angle sector 201. The state "0" also means that the low-side switching element 104 for the corresponding phase is closed at least temporarily (e.g., for one or more pulses) in the corresponding angle sector 201 (to generate one or more pulses with the low-side potential).

[0059] On the other hand, the state "1" means that the high-side switching element 102 for the corresponding phase is closed at least temporarily (e.g., for one or more pulses) in the corresponding angle sector 201 (to generate one or more pulses with the high-side potential). The state "1" also means that the low-side switching element 104 for the corresponding phase is continuously open in the corresponding angle sector 201.

[0060] As can be seen from Table 1a and Table 1b, a high-side angle range can be defined for each phase u, v, w, respectively, which respectively includes three angle sectors 201, in which the corresponding phase has the state "1" (and in which one or more pulses are caused by the high-side switching element 102). For phase u (in I q <0 case), the high-side angle range extends over angle sectors 2, 3, and 4 (see Table 1a). For phase v (in I q <0 case), the high-side angle range extends over angle sectors 4, 5, and 6 (see Table 1a). For phase w (in I q <0 case), the high-side angle range extends over angle sectors 1, 2, and 6 (see Table 1a).

[0061] Thus, for each phase, a high-side angle range is generated respectively, in which the high-side switching element 102 of the corresponding phase is closed in a pulsed manner to provide a particularly efficient and reliable emergency operation mode.

[0062] Figure 3 Shows for the case of I q <0, the high-side angle ranges 313 for different phases u 301, v 302, and w 303 over a complete cycle (0 - 2π) of the electrical rotor angle 305. Outside the corresponding high-side angle ranges 313, the high-side switching elements 102 of the corresponding phases 301, 302, 303 remain open. Within the corresponding high-side angle ranges 313, the high-side switching elements 102 can be closed in a pulsed manner, as shown by the pulses 312. The pulses 312 in the different phases 301, 302, 303 are synchronized with each other in time. In other words, the pulses 312 in the high-side angle ranges 313 of two different phases 301, 302, 303 are synchronized with each other in time.

[0063] The pulses 312 can be repeated at a specific pulse frequency f. The pulse frequency f can be adjusted according to the angular velocity of the rotor of the electric machine 103. Here, the pulse frequency f is preferably so high that six or more pulses 312 are generated within a complete cycle of the electrical rotor angle 305 (i.e., at least one pulse 312 per angular sector 201).

[0064] Between directly successive pulses 312, idling of the phases 301, 302, 303 or alternatively short-circuiting of the phases can be caused within an intermediate interval. From the pulse frequency f, a pulse period 314 with a specific period duration T is obtained, where T = 1 / f. The pulse duration 316 of the pulses 312 and the interval duration 315 of the intermediate intervals can together exactly result in the period duration T. The ratio of the pulse duration 316 to the interval duration 315 can be adjusted to optimize the emergency operation mode.

[0065] Thus, in the emergency operation mode, a high-side angle range 313 can be defined respectively for each phase 301, 302, 303, and the high-side angle ranges respectively extend over a specific partial range of a complete cycle of the electrical rotor angle 305. Furthermore, it can be caused (by closing the corresponding high-side switching elements 102) that voltage pulses 312 (with a high-side potential) are caused within the corresponding high-side angle ranges 313 at a specific pulse frequency f. During the intermediate intervals between the individual pulses 312, idling or short-circuiting of the phases 301, 302, 303 can be caused.

[0066] Furthermore, a low-side angle range 313 can be defined for the low-side switching element 104 in a complementary manner, so that a low-side pulse 312 (with a low-side potential) is generated by closing the low-side switching element 104 within the corresponding low-side angle range 313. In the intermediate intervals between the individual pulses 312, idling or short-circuiting of phases 301, 302, 303 can be caused. The low-side angle ranges 313 for phases 301, 302, 303 correspond to the angle sectors 201 in which the said phases 301, 302, 303 have the state "0".

[0067] It can be demonstrated that in the idling case (when idling of phases 301, 302, 303 is caused in the intermediate intervals), an increase in the intermediate circuit voltage can be prevented and a decrease in the intermediate circuit voltage can be caused. Furthermore, the amplitude of the transient current can be limited. Correspondingly, it can be demonstrated that in the active short-circuit case (when active short-circuiting of phases 301, 302, 303 is caused in the intermediate intervals), the transient short-circuit current can be significantly reduced (by approximately 60%), and the voltage in the intermediate circuit can be reduced.

[0068] Figure 4a An exemplary device 400 for operating a motor 103 is shown. The device 400 has an emergency operation module 401 for an emergency operation mode and a standard module 402 for a standard operation mode. In response to a fault signal 405, a switchover from the standard operation mode to the emergency operation mode can be effected by a switching unit 403.

[0069] Figure 4b More details of the emergency operation module 401 are shown. In a logic module 411, it can be determined, based on the respectively current angle values of the electrical rotor angle 305 (and based on the sign 418 of the I q current), which of the individual phases 301, 302, 303 are in the high-side angle range 313 or the low-side angle range 313. In particular, the switching pattern 205 for the current angle value of the electrical rotor angle 305 can be determined. For this purpose, the logic module 411 can have a look-up table (for example based on Table 1a and / or Table 1b).

[0070] In a pulse generator 412, a pulse sequence 415 can be generated for the individual phases 301, 302, 303 for the determined switching pattern 205, in particular a pulse sequence for the switching elements 102, 104 of the individual phases 301, 302, 303. Here, it can be indicated by an FL / AKS indicator 417 whether FL operation or AKS operation should be caused in the intermediate intervals between the pulses 312. Furthermore, the pulse sequence 415 can be generated as a function of the pulse frequency or the pulse frequency f 415 and / or as a function of the ratio 413 of the pulse duration 316 to the interval duration 315. Furthermore, the total duration 414 for the emergency operation mode can be taken into account.

[0071] Figure 5 Shows a flowchart of a method 500 (optionally computer-implemented) for providing an emergency operating mode of an electric machine 103. The electric machine 103 operates with Q different phases 301, 302, 303, which vary between a high-side potential (e.g., U DC / 2) and a low-side potential (e.g., -U DC / 2), where Q ≥ 3. In the standard operating mode, sinusoidal phase voltages 111 and / or phase currents 112 can be generated by corresponding operation of the inverter 100 (as shown in conjunction with Figure 1a and Figure 1b ). In the emergency operating mode, the inverter 100 can generate a pulse sequence for the Q phases 301, 302, 303 in order to achieve an efficient, reliable, and gentle reduction of the energy stored in the electric machine 103.

[0072] The method 500 can be repeated at a series of moments. Here, the method 500 can respectively include, at each moment: determining 501 the angular value of the electrical rotor angle 305 of the electric machine 103 at the corresponding moment. The angular value can be determined by means of a suitable sensor of the electric machine 103.

[0073] The method 500 further includes: based on the angular value of the electrical rotor angle 305, determining 502 for each of the Q phases 301, 302, 303 whether the corresponding phase is or should be in the high-side state (i.e., state "1") or the low-side state (i.e., state "0"). This (i.e., the target state) can be determined by means of Table 1a or Table 1b or by means of Figure 2a or Figure 2b .

[0074] In addition, the method 500 includes: generating 503 a pulse sequence 415 for each of the Q phases 301, 302, 303. The pulse sequence 415 for one phase 301, 302, 303 can respectively include one or more pulses 312 each having a pulse duration 316. Here, the one or more pulses 312 can succeed each other at a pulse frequency 415. The pulse frequency 415 and / or the pulse duration 316 can be determined, for example, according to the angular velocity of the rotor of the electric machine 103 at the corresponding moment.

[0075] When the corresponding phase 301, 302, 303 is or should be in the high-side state at the corresponding moment, each pulse 312 can have the high-side potential. On the other hand, when the phase 301, 302, 303 is or should be in the low-side state, each pulse 312 can have the low-side potential. Among them, the (temporal) pulses 312 of at least two phases 301, 302, 303 can respectively all have the high-side potential or all have the low-side potential.

[0076] Through the various aspects described herein, particularly efficient and reliable emergency operation of the electric machine 103 can be achieved.

[0077] The invention is not limited to the embodiments shown. In particular, it should be noted that the description and the drawings are only to illustrate the principles of the proposed methods, devices, and systems in an exemplary manner.

Claims

1. A device (101) for providing an emergency operation mode of an electric machine (103), wherein, The electric machine (103) operates with Q different phases (301, 302, 303), each of which varies between a high-side potential and a low-side potential, where Q ≥ 3; the device (101) is configured to, respectively, for one moment in a series of successive moments: - Determine an angular value of the electrical rotor angle (305) of the electric machine (103) at the corresponding moment; - Based on the angular value of the electrical rotor angle (305), determine for each of the Q phases (301, 302, 303): whether the corresponding phase should be in a high-side state or a low-side state; and - Generate a pulse sequence (415) for each of the Q phases (301, 302, 303) respectively; where: -- The pulse sequence (415) for one phase (301, 302, 303) respectively includes one or more pulses (312), and the pulses respectively have a pulse duration (316), - The one or more pulses (312) succeed each other at a pulse frequency (415), -- When the corresponding phase (301, 302, 303) should be in a high-side state, the pulse (312) has a high-side potential, and -- When the phase (301, 302, 303) should be in a low-side state, the pulse (312) has a low-side potential.

2. The device (101) according to claim 1, where: - The pulse sequence (415) respectively has an intermediate interval with an interval duration (315) between two directly successive pulses (312); - The device (101) is configured to, respectively, cause the Q phases (301, 302, 303) to idle or short-circuit during the intermediate interval.

3. The device (101) according to claim 2, wherein, The device (101) is configured to: - Decouple the Q phases (301, 302, 303) from the high-side potential and from the low-side potential to cause the Q phases (301, 302, 303) to idle; and / or - Couple the Q phases (301, 302, 303) to each other to cause the Q phases (301, 302, 303) to short-circuit.

4. The device (101) according to any one of the preceding claims, wherein, The one or more pulses (312) in the pulse sequences (415) of the Q phases (301, 302, 303) are synchronized with each other in time.

5. The device (101) according to any one of the preceding claims, wherein, The pulse sequences (415) of the Q phases (301, 302, 303) are configured such that: - The pulse sequences (415) for two different phases (301, 302, 303) respectively have simultaneous pulses (312), both of which have a high-side potential or both of which have a low-side potential; and / or - The pulse sequences (415) for the Q phases (301, 302, 303) respectively have simultaneous pulses (312), and in each of the pulses, every two pulses respectively have a high-side potential or a low-side potential.

6. The apparatus (101) according to any one of the preceding claims, wherein, The device (101) is configured to: - Determine one or more operating parameters of the electric machine (103) at the moment, the one or more operating parameters particularly including the angular velocity of the electric machine (103); And - Determine the pulse frequency (415) and / or the pulse duration (316) based on the one or more operating parameters.

7. The device (101) according to any one of the preceding claims, wherein, The device (101) is configured to determine the pulse frequency (415) such that the pulse sequence (415) of the Q phases (301, 302, 303) includes 2*Q or more pulses (312) respectively for a complete cycle of the electrical rotor angle (305).

8. The device (101) according to any one of the preceding claims, wherein: - The device (101) is configured to determine for each of the Q phases (301, 302, 303) by means of a predefined allocation unit (411): whether the corresponding phase (301, 302, 303) should be in a high-side state or a low-side state; and - The allocation unit (411) is configured to indicate for a plurality of different angular values of the electrical rotor angle (305) whether the corresponding phase (301, 302, 303) should be in a high-side state or a low-side state respectively.

9. The apparatus (101) according to any one of the preceding claims, wherein, The device (101) is configured to: - Determine the polarity of the current of the I in the dq coordinate system of the motor (103); and q And -According to I q Based on the polarity of the current, the corresponding phases (301, 302, 303) should be in the high-side state or the low-side state.

10. The apparatus (101) according to any one of the preceding claims, wherein, For Q = 3 and I q <0: - The first phase (u, 301) should be in a high-side state for an angular value of the rotor angle (305) of [9π / 12 - 21π / 12], otherwise it should be in a low-side state; - The second phase (v, 302) should be in a high-side state for angular values of the rotor angle (305) of [0 - 5π / 12] and [17π / 12 - 2π], otherwise it should be in a low-side state; and - The third phase (w, 303) should be in a high-side state for an angular value of the rotor angle (305) of [π / 12 - 13π / 12], otherwise it should be in a low-side state.

11. The device (101) according to any one of the preceding claims, wherein, For Q = 3 and I q > 0: - The first phase (u, 301) should be in a high-side state for an angular value of the rotor angle (305) of [π / 4 - 15π / 12], otherwise it should be in a low-side state; - The second phase (v, 302) should be in a high-side state for an angular value of the rotor angle (305) of [11π / 12 - 23π / 12], otherwise it should be in a low-side state; and - The third phase (w, 303) should be in a high-side state for angular values of the rotor angle (305) of [0 - 7π / 12] and [19π / 12 - 2π], otherwise it should be in a low-side state.

12. A method (500) for providing an emergency operation mode of an electric machine (103), wherein, The electric machine (103) operates with Q different phases (301, 302, 303), each of which varies between a high-side potential and a low-side potential, where Q≥3; the method (500) for each of a series of successive instants respectively includes: - Determine (501) the angular value of the electrical rotor angle (305) of the electric machine (103) at the corresponding instant; - Based on the angular value of the electrical rotor angle (305), determine (502) for each of the Q phases (301, 302, 303): whether the corresponding phase should be in a high-side state or a low-side state; and - Generate (503) a pulse sequence (415) for each of the Q phases (301, 302, 303); wherein: --The pulse sequences (415) for one phase (301, 302, 303) each include one or more pulses (312), which respectively have pulse durations (316). - The one or more pulses (312) succeed each other at a pulse frequency (415). --When the corresponding phase (301, 302, 303) is to be in the high-side state, the pulses (312) have a high-side potential, and --When the phase (301, 302, 303) is to be in the low-side state, the pulses (312) have a low-side potential.

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