Method for operating a brushless electric motor having improved emergency switch-off

Abstract

The present invention in general relates to a method for operating a brushless electric motor having improved emergency switch-off, and to an electric motor that is designed accordingly.

Description

[0001] Method for operating a brushless electric motor with improved emergency shutdown

[0002] Description

[0003] The present invention relates generally to a method for operating a brushless electric motor with improved emergency shutdown and to a correspondingly designed electric motor.

[0004] Safety-relevant systems, such as a motor vehicle's braking systems, must be restored to a safe operating state in the event of a dangerous malfunction. For example, the ISO 26262 standard specifies safety integrity levels for such safety-relevant systems in motor vehicles.

[0005] In some applications with electronically controlled brushless DC motors, a safe system state is achieved, for example, by actively driving the brushless DC motor into a predetermined operating state, for example a decoupled state in the case of a gear actuator.

[0006] Alternatively, the system can be brought into a safe operating state using mechanical means, for example, by decoupling it using a spring. However, this can significantly reduce the probability of reaching operating states with high safety requirements in the event of malfunctions in the electronic drive control system. However, the use of mechanical means such as a spring can be complex to construct and also costly.

[0007] Other methods may provide computer or microcontroller support. For example, if the power supply is interrupted or the electrical voltage drops below a predetermined threshold at the engine control unit (MCU), electrical engine braking can be switched to a kind of worst-case scenario, in which the transistors are switched to achieve a safe operating state. The disadvantage of these methods is that this is only possible for very short periods of time, usually in the range of well under 1 s, for example, approximately 0.25 s, so that the safe operating state may not be achieved.

[0008] Therefore, methods for operating a brushless DC motor that do not have the aforementioned disadvantages or at least mitigate them are desirable. A method in which the time until a safe operating state is reached is increased, so that this safe operating state can actually be achieved, is particularly desirable.

[0009] The inventors have taken on this task.

[0010] This problem is solved surprisingly simply by a method for operating a three-phase brushless electric motor, a motor control unit, and a braking system according to one of the independent claims. Preferred embodiments and further developments of the invention can be found in the respective subclaims.

[0011] The present invention therefore relates, in a first aspect, to a method for operating a three-phase brushless electric motor with a circuit arrangement comprising:

[0012] - a power converter having an electrical half-bridge with an electronic high-side switch and an electronic low-side switch for each phase of the brushless electric motor, and with

[0013] - an electronic control unit for controlling the electronic switches of the power converter.

[0014] The procedure includes the following steps: - Detecting the applied voltage,

[0015] - comparing the applied voltage with a predetermined voltage limit,

[0016] - controlling the power converter during operation of the brushless electric motor according to a normal operating procedure when the applied voltage is within a predetermined range, or

[0017] - switching from the normal operating procedure to an emergency operating procedure when the applied voltage falls below a predetermined voltage limit, and

[0018] - Operating the brushless electric motor in the emergency operation procedure

[0019] The brushless electric motor can be powered from the vehicle's electrical system, for example, in the case of a motor vehicle's braking system. The brushless electric motor can be controlled by an engine control unit. This can also be powered by voltage from the vehicle's electrical system. Typically, predetermined voltage limits must be observed for the engine control unit to operate properly. If the voltage drops below a predetermined threshold, proper operation can no longer be guaranteed. For brushless electric motors or corresponding engine control units used in motor vehicles, for example, an operating voltage of approximately 6 V to 38 V may be required to ensure proper operation.

[0020] If, for example, the voltage drops below 7 V, the motor control unit can be shut down. The problem in such cases is that the brushless electric motor must be brought into a safe operating state, especially if it was running at the time of the power failure. This may mean that the brushless electric motor must be braked to a standstill or at least slowed to a rotor speed at which no damage to the brushless electric motor or other components occurs. For example, damage can occur if the brushless electric motor is used for a linear actuator in a braking system and end stops are touched due to high rotation speeds.

[0021] For such cases, in addition to the normal operating mode, in which the brushless electric motor can be operated without problems, an emergency operating mode is provided. This is activated when the applied voltage falls below a predetermined threshold. It may be important to supply the engine control unit with sufficient voltage even in the emergency operating mode to ensure safe operation.

[0022] The invention enables the return of a large portion of the energy of the brushless electric motor, which results from the electromagnetic torque during operation of the brushless electric motor, back into the vehicle's electrical system or into an energy storage unit. This can occur during generator operation or generator mode of the brushless electric motor. The generator mode can therefore be a component of the emergency operating procedure.

[0023] To operate the three-phase brushless electric motor, a circuit arrangement can be provided that includes a power converter, which can have an electrical half-bridge for each phase of the brushless electric motor, each with an electronic high-side switch and an electronic low-side switch, as well as corresponding connection terminals. The connection terminals can be designed as KL30.

[0024] The stator phase windings of the brushless electric motor can be connected to the converter's output terminals in a conventional manner. Furthermore, a motor control unit can be provided to control the converter's electronic switches.

[0025] The electronic switches, i.e., the electronic high-side switches and the electronic low-side switches, are preferably designed as transistors, preferably as insulated-gate field-effect transistors, such as MOSFETs or IGBTs, as are often used in converters for controlling brushless electric motors. The transistors are preferably designed with a body effect or each include a body diode. The coils of the brushless electric motor can be connected to the transistors in a star or delta configuration.

[0026] The energy storage unit can be configured by at least two parallel-connected power capacitors of the associated circuit arrangement. This can also include a brake absorber for excess energy. These power capacitors can be charged during the emergency operating mode.

[0027] This makes it possible to charge the power capacitors in the emergency mode via the body diodes or the body effect of the transistors, for example, when the voltage supply drops below a critical value during operation of the brushless electric motor or when the voltage falls below a predetermined limit. The invention thus utilizes the mechanical energy generated by the rotational movement of the brushless electric motor during operation to generate electrical energy.

[0028] The method can provide for detecting the applied voltage and comparing it with a predetermined voltage limit. The detection and measurement of the voltage can be performed, for example, at the connection terminals. In the event that the electrical voltage drop cannot be detected at the connection terminals, additional tracking filters can be implemented to estimate voltage dips.

[0029] The brushless electric motor can be controlled according to a normal operating mode if the applied voltage is within a predetermined range. If the applied voltage falls below a predetermined voltage threshold, a switch from the normal operating mode to an emergency operating mode can occur, in which the brushless electric motor can then be operated in the emergency operating mode.

[0030] The predetermined voltage threshold may depend on the intended application. In the case of an engine control unit for a motor vehicle's braking system, the voltage threshold that triggers a transition from a normal operating mode to an emergency operating mode may be 6 to 7 V, for example.

[0031] According to the invention, at least two different methods are provided for the emergency operating procedure.

[0032] According to the invention, a first emergency operating mode, also referred to as a short-circuit emergency operating mode, can be used at lower rotor speeds, and a second emergency operating mode, also referred to as an OW emergency operating mode, can be used at higher rotor speeds. These can be selected depending on the rotor speed of the brushless electric motor.

[0033] The two emergency operating methods according to the invention can also be used alternately. Controlling them with at least two different emergency operating methods makes it highly advantageous to ensure predominantly regenerative and highly efficient operation within the emergency mode.

[0034] The short-circuit emergency operating mode is intended to ensure that the electrical voltage at the connection terminals of the circuit arrangement does not fall below the critical value required for the operation of the engine control unit or other components of the circuit arrangement, in particular the required ICs. If this condition is met, the invention allows switching to the OW emergency operating mode, in which the power capacitors can be charged. If the electrical voltage at the connection terminals falls below the critical value again, the system can switch back to the short-circuit emergency operating mode.

[0035] To determine the respective control method in emergency operation, the invention can provide for the current rotor speed to be recorded at least in the emergency operation mode. The limit value for the rotor speed, which is used to select the first or second emergency operation mode, can be determined depending on the engine characteristics and stored in an electronic memory.

[0036] The first or short-circuit emergency operating procedure corresponds to a procedure in which the electronic low-side switches (L1, L2, L3) are switched on or conductive and the electronic high-side switches (H1, H2, H3) are switched to the open or high-impedance switching state.

[0037] The second, or OW, emergency operating mode (“OW” = “open winding”) corresponds to a mode in which both the electronic low-side switches (L1, L2, L3) and the electronic high-side switches (H1, H2, H3) are switched to the open or high-impedance state. This mode therefore establishes a predominantly regenerative or generator mode, which can be used at medium to high rotor speeds. This allows for better utilization of the mechanical energy of the high-speed brushless electric motor or the motor torque, which can be converted into the resulting electrical voltage to charge the power capacitors.

[0038] This can significantly improve both the dynamic behavior and the efficiency of the braking system. In particular, the electrical energy of the high-speed brushless electric motor can be fed back into the vehicle's electrical system or used to charge the power capacitors during the generator mode. This generator mode can be achieved particularly easily if the body diodes of the transistors are appropriately polarized by the resulting counter-electromotive forces that arise when the rotor of the brushless electric motor rotates in a surrounding magnetic field. With each rotation of the rotor, a voltage is induced, which is determined by the speed and the magnetic flux linkage.

[0039] Due to the regenerative nature of this OW emergency operating procedure, the resulting electrical energy of the brushless electric motor can be used, preferably until a specified voltage limit is reached, in order to avoid, for example, an overload of the on-board electrical system or an engine control unit.

[0040] In this way, for example, the engine control unit can be kept operational for significantly longer, even if the voltage, for example in the vehicle's electrical system, has fallen below the limit. This extension can range from a few milliseconds to a few seconds, allowing, for example, a controlled shutdown or at least the achievement of a safe operating state. The specific time period depends on the current operating parameters of the brushless electric motor, such as the design or the rotor speed at the time of the voltage interruption.

[0041] The resulting electromagnetic torque and subsequently the mechanical output torque developed by the brushless electric motor during this regenerative OW emergency operation mode is significantly higher than that developed in the short-circuit emergency operation mode.

[0042] This allows for better and more efficient control of the brushless electric motor, especially in emergency situations. In particular, a brushless electric motor can operate longer during power or voltage interruptions by converting the mechanical rotational energy applied to the rotor shaft into a nearly equivalent electrical energy.

[0043] The invention offers the great advantage of being easy to implement, as no changes to existing hardware, such as the inverter design, are required. Rather, the method can be implemented using appropriate algorithms, which can be implemented, for example, in existing engine control unit programs.

[0044] In the OW emergency operating mode, the power capacitors can be charged until the predetermined voltage limit is reached. Any excess electrical energy can be fed to the brake absorber.

[0045] The voltage applied to the connection terminals of the circuit arrangement to the vehicle's electrical system is detected.

[0046] The three-phase brushless electric motor can be designed as either a DC motor or an AC motor, thus providing a wide range of applications.

[0047] In a further aspect, the invention encompasses a motor control unit, in particular for controlling a three-phase brushless electric motor, comprising a computer unit with a memory, wherein the computer unit can be designed to carry out the method according to the invention as described above. The limit values ​​for the voltage and / or the rotor speed can be stored in the memory. The motor control unit can be integrated into the motor control unit or be a component thereof.

[0048] Furthermore, a brushless electric motor comprising a motor control unit for controlling the brushless electric motor as described above is also encompassed by the invention. In yet another aspect, the invention also encompasses a braking system, in particular for a motor vehicle, comprising a motor control unit as described above. The brushless electric motor can be used, for example, in conjunction with pumps for applying hydraulic pressure, as well as in conjunction with so-called "dry," electromechanical brakes.

[0049] Preferred embodiments and further developments of the invention can be found in the respective subclaims, the content of which is made part of the present description by express reference.

[0050] The drawings show:

[0051] Fig. 1 is a simplified block diagram of an engine control unit according to the invention,

[0052] Fig. 2 a simplified representation of the power converter,

[0053] Fig. 3 shows a simplified schematic representation of a circuit architecture,

[0054] Fig. 4 shows a simplified schematic representation of another circuit architecture, and

[0055] Fig. 5 shows a simplified schematic representation of a circuit architecture according to the invention,

[0056] Fig. 6 shows an exemplary profile of the rotor speed of an exemplary brushless electric motor,

[0057] Fig. 7 shows an example of the course of torque, current vector and power in an emergency operating method and Fig. 8 shows an example of the course of torque, current vector and power for the emergency operating method according to the invention.

[0058] In the following detailed description of preferred embodiments, for the sake of clarity, like reference numerals designate substantially similar parts in or on these embodiments. However, to better illustrate the invention, the preferred embodiments illustrated in the figures are not always drawn to scale.

[0059] Fig. 1 schematically shows a simplified block diagram of a motor control unit 1 for controlling a three-phase brushless electric motor 16. The motor control unit 1 comprises a power converter 15, which has an electrical half-bridge for each phase of the brushless electric motor 16. Fig. 2 shows a simplified representation of the power converter 15.

[0060] The engine control unit 1 comprises two connection terminals 11.1, 11.2, which are connected to a voltage source 10 and are designed as terminals KL30_1, KL30_2. The voltage source 10 is designed as a DC voltage source and can be represented, for example, by the on-board electrical system of a motor vehicle or a vehicle battery. In the exemplary embodiment, the engine control unit 1 further comprises a reverse polarity protection circuit 12 and a brake absorber 13. Furthermore, the engine control unit 1 comprises two power capacitors 14.1, 14.2 connected in parallel. Other parts and components, such as the engine control unit (ECU) 20, are not shown for the sake of clarity.

[0061] The power converter 15 shown in Fig. 2, which is suitable for the invention, comprises three electrical half-bridges 17.1, 17.2, 17.3 for each phase of the brushless electric motor 16. Each electrical half-bridge 17.1, 17.2, 17.3 is designed with an electronic high-side switch H1, H2, H3 and an electronic low-side switch L1, L2, L3. Between these electronic switches H1, H2, H3, L1, L2, L3, connecting terminals or bridge branches are provided for connecting the brushless electric motor 16.

[0062] The first electronic switches H1, H2, and H3 are connected to a positive pole of the power supply or voltage source 10. The second electronic switches L1, L2, and L3 are connected to a negative pole of the power supply or voltage source 10. The electronic switches H1, H2, H3, L1, L2, and L3 are each designed as a MOSFET (metal oxide semiconductor field-effect transistor) with a body effect.

[0063] Figures 3 and 4 each schematically show a simplified representation of two prior art circuit architectures 2, 3. In this case, the off state of the brushless electric motor 16 is achieved by interrupting the high-current path with at least one of the shutdown paths 18, 19, with the switching being performed by the motor control unit 20.

[0064] The shutdown path 18 can be implemented as a logic-level (low-current) deactivation path. The power converter 15 is a three-phase inverter as described above. The shutdown path 19 can be implemented as an electromechanical relay or a static relay and interrupts high electrical currents that flow from the power converter 15 to the electric motor 16 during normal operation.

[0065] A circuit architecture 4 according to the invention is shown in Fig. 5. This is designed such that the off state of the brushless electric motor 16 is achieved only by using shutdown paths 18, 19 at the logic level in combination with an intelligent motor control strategy.

[0066] The method according to the invention for operating the three-phase brushless electric motor 16 comprises the following steps:

[0067] - Detecting the applied voltage, - Comparing the applied voltage with a predetermined voltage limit,

[0068] - controlling the power converter 15 during operation of the brushless electric motor 16 according to a normal operating procedure when the applied voltage is within a predetermined range, or

[0069] - Switching from the normal operating procedure to a

[0070] Emergency operating procedures when the applied voltage falls below a predetermined voltage limit, and

[0071] - Operating the brushless electric motor 16 in the emergency operation procedure.

[0072] To operate the three-phase brushless electric motor 16, a circuit arrangement as shown in Fig. 1 is provided.

[0073] The method involves detecting the applied voltage and comparing it with a predetermined voltage limit. The brushless electric motor 16 is then controlled according to a normal operating procedure if the applied voltage is within a predetermined range or does not fall below the specified limit.

[0074] If the applied voltage falls below the predetermined limit value for the voltage, the computer-assisted switching from the normal operating mode to the emergency operating mode takes place, in which the brushless electric motor 16 is operated in the emergency operating mode until a predetermined safe operating state is reached.

[0075] The predetermined voltage limit is preferably determined in advance for the specific application. For example, for engine control units used in automotive braking systems, it can be 6 to 7 V. Falling below this voltage limit would lead to unstable or faulty operation of the engine control unit, which may require an emergency shutdown. In particular, ICs or semiconductor components can be damaged if specified operating parameters are not maintained.

[0076] According to the invention, at least two different methods are provided for the emergency operating procedure. These are selected and implemented with computer support depending on the rotor speed of the brushless electric motor 16 at the time of the voltage deviation.

[0077] According to the invention, a first short-circuit emergency operating method is used for emergency shutdown at lower rotor speeds and a second OW emergency operating method is used for emergency shutdown at higher rotor speeds.

[0078] For this purpose, the current rotor speed of the brushless electric motor 16 is detected. This can be done using known motor encoders, but indirect methods, such as voltage or current monitoring, can also be used.

[0079] The rotor speed limit value used to select the first or second emergency operating procedure is determined depending on the engine characteristics and stored in an electronic memory for use in the procedure.

[0080] The short-circuit emergency operating procedure corresponds to a procedure in which the electronic low-side switches (L1, L2, L3) are switched on or conductive, and the electronic high-side switches (H1, H2, H3) are switched to the open or high-impedance state. This corresponds to a short circuit of the motor terminals as soon as the supply voltage drops below the voltage limit.

[0081] The second OW emergency operating mode is selected if the rotor speed exceeds the predetermined rotor speed limit at the time of the voltage drop or at a later time. In this mode, both the electronic low-side switches (L1, L2, L3) and the electronic high-side switches (H1, H2, H3) are switched to the open or high-impedance state.

[0082] In the OW emergency operating procedure, the mechanical energy of the brushless electric motor can be converted into electrical energy during a generator regime and fed back into the vehicle's electrical system or preferably used to charge the power capacitors.

[0083] In this way, the engine control unit 20 can be kept operational for significantly longer, even if the voltage, for example in the vehicle's electrical system, has fallen below the limit. This extension can range from a few milliseconds to a few seconds, allowing, for example, a controlled shutdown. This time period results from the respective current operating parameters of the brushless electric motor, for example, the rotor speed at the time of the voltage interruption.

[0084] The resulting electromagnetic torque and subsequently the mechanical output torque developed by the brushless electric motor during this regenerative OW emergency operation mode is significantly higher than that developed in the short-circuit emergency operation mode.

[0085] Based on simulations, the emergency operating method according to the invention, as a combination of the short-circuit emergency operating method and the OW emergency operating method, was compared with an emergency operating method according to the state of the art.

[0086] Fig. 6 shows an exemplary profile of the rotor speed of an exemplary brushless electric motor 16 over a period of 2.5 s, which was used as a basis for the simulations.

[0087] Fig. 7 shows an example of the torque, current vector, and power curves in an emergency operating procedure according to the prior art. Reference numeral 30 denotes the mechanical torque, 31 the electromagnetic torque, 40 the measured current vector, and 41 the measured current vector. Furthermore, reference numeral 50 denotes the mechanical power, and 51 the electrical power.

[0088] Fig. 8 shows an example of the torque, current vector, and power curves for the emergency operating method according to the invention. In the exemplary embodiment, it was assumed that the rotor speed limit was approximately 1,600 rpm. Below this limit, the short-circuit emergency operating method was used, and above this limit, the new OW emergency operating method was used. The result shows that significantly higher power values ​​can be achieved through more efficient use of the range where the rotor speed is above 1,600 rpm.

[0089] This allows for better and more efficient control of the brushless electric motor 16, especially in emergency situations.

[0090] In the OW emergency operating mode, the power capacitors 14.1, 14.2 are charged until the predetermined voltage limit is reached. Any additional excess electrical energy is supplied to the brake absorber 13.

[0091] The applied voltage is detected at the connection terminals of the circuit arrangement to the vehicle's electrical system.

[0092] The three-phase brushless electric motor 16 can be designed either as a direct current motor, as in the present case, or as an alternating current motor.

[0093] In a further aspect, the invention also encompasses a motor control unit 1, in particular for controlling a three-phase brushless electric motor 16, comprising a computer unit with a memory, wherein the computer unit is designed to carry out the method according to the invention as described above. The limit values ​​for the voltage and / or the rotor speed are stored in the memory.

[0094] Accordingly, a brushless electric motor 16 comprising a motor control unit 1 for controlling the brushless electric motor 16 as described above is also encompassed by the invention.

[0095] In yet another aspect, the invention encompasses a braking system, in particular for a motor vehicle, comprising an engine control unit 1 as described above. The brushless electric motor 16 can be used, for example, in conjunction with pumps for applying hydraulic pressure, as well as in conjunction with so-called "dry," electromechanical brakes.

[0096] B ezu q sze i chenliste:

[0097] 1 engine control unit

[0098] 2 Circuit architecture

[0099] 3 Circuit architecture

[0100] 4 Circuit architecture

[0101] 10 Voltage source

[0102] 11.1 Connection terminal (KL30_1)

[0103] 11 .2 Connection terminal (KL 30_2)

[0104] 12 Reverse polarity protection circuit

[0105] 13 brake absorbers

[0106] 14.1 Power capacitor

[0107] 14.2 Power capacitor

[0108] 15 power converters

[0109] 16 electric motor

[0110] 17.1 Half bridge

[0111] 17.2 Half bridge

[0112] 17.3 Half bridge

[0113] 18 shutdown path

[0114] 19 Shutdown path

[0115] 20 Engine control unit

[0116] H1 switch

[0117] H2 switch

[0118] H3 switch

[0119] L1 switch L2 switch

[0120] L3 switch

[0121] PWM_H1 control signal

[0122] PWM_H2 control signal

[0123] PWM_H3 control signal

[0124] PWM_L1 control signal

[0125] PWM_L1 control signal

[0126] PWM_L1 control signal

[0127] 30, 30' torque

[0128] 31.31' torque

[0129] 40, 40' current vector

[0130] 41 , 41' Current vector

[0131] 50, 50' performance

[0132] 51.51' performance

Claims

1. Method for operating a three-phase brushless electric motor (16) with a circuit arrangement (1 ) comprising: - a power converter (15) which has an electrical half-bridge (17.1, 17.2, 17.3) for each phase of the brushless electric motor (16), each with an electronic high-side switch (H1, H2, H3) and an electronic low-side switch (L1, L2, L3), and with - an electronic control unit for controlling the electronic switches (H1, H2, H3, L1, L2, L3) of the power converter (15), the method comprising the following steps: - Detecting the applied voltage, - comparing the applied voltage with a predetermined voltage limit, - controlling the power converter (15) during operation of the brushless electric motor (16) according to a normal operating method when the applied voltage is within a predetermined range, or - switching from the normal operating procedure to an emergency operating procedure when the applied voltage falls below a predetermined voltage limit, and - Operating the brushless electric motor (16) in the emergency operation procedure.

2. Method according to the preceding claim, characterized in that the electronic switches (H1, H2, H3, L1, L2, L3) are designed as a transistor, preferably as a field-effect transistor and particularly preferably as a MOSFET or as an IGBT.

3. Method according to one of the preceding claims, characterized in that the circuit arrangement (1) comprises at least two parallel-connected power capacitors (14.1, 14.2) and / or a brake absorber (13).

4. Method according to one of the preceding claims, characterized in that at least in the emergency operating method the current rotor speed is detected.

5. Method according to one of the preceding claims, characterized in that the emergency operating method comprises a first short-circuit emergency operating method and a second OW emergency operating method.

6. Method according to one of the preceding claims, characterized in that the limit value for the rotor speed is determined as a function of the motor characteristics and is provided in an electronic memory.

7. Method according to one of the preceding claims, characterized in that the short-circuit emergency operating method is selected when the current rotor speed is below a predetermined limit value for the motor speed.

8. Method according to one of the preceding claims, characterized in that in the short-circuit emergency operating method the electronic low-side switches (L1, L2, L3) are switched on or conductive and the electronic high-side switches (H1, H2, H3) are switched to the open or high-impedance switching state.

9. Method according to one of the preceding claims, characterized in that the OW emergency operating method is selected when the current rotor speed is above a predetermined limit value for the engine speed.

10. Method according to one of the preceding claims, characterized in that in the OW emergency operating procedure the electronic low-side switches (L1, L2, L3) and the electronic high-side switches (H1, H2, H3) are switched to the open or high-impedance switching state.

11. Method according to one of the preceding claims, characterized in that in the OW emergency operating method, regenerative operation takes place, wherein an electrical voltage is generated by the engine torque (16), whereby the power capacitors (14.1, 14.2) are charged.

12. Method according to one of the preceding claims, characterized in that in the OW emergency operating method the power capacitors (14.1, 14.2) are charged until the predetermined voltage limit is reached and the excess electrical energy is absorbed by the brake absorber (13).

13. Method according to one of the preceding claims, characterized in that the detection of the applied voltage takes place at the connection terminals (11.1, 11.2) of the circuit arrangement (19).

14. Method according to one of the preceding claims, characterized in that the three-phase brushless electric motor (16) is designed as a direct current motor or as an alternating current motor.

15. Motor control unit, in particular for controlling a three-phase brushless electric motor (16), comprising a computer unit with a memory, wherein the computer unit is designed to carry out a method according to one of the preceding claims.

16. Braking system, in particular for a motor vehicle, comprising an engine control unit according to the preceding claim.

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