Method for operating a brushless electric motor with optimized emergency shutdown

Abstract

The present invention relates generally to a method for operating a brushless electric motor and a correspondingly designed electric motor. The electric motor can, in particular, be a component of an electromechanical braking device. The method for controlling the electric motor can include a control circuit and an emergency circuit arrangement, wherein in a normal operating mode the electric motor is controlled by the control circuit, and wherein in the event of a failure of the control circuit the control of the electric motor is taken over by the emergency circuit arrangement based on an emergency stop program.

Description

[0001] The present invention relates generally to a method for operating a brushless electric motor and a correspondingly designed electric motor. The electric motor can, in particular, be a component of an electromechanical braking device.

[0002] Modern motor vehicles use electromechanically actuated wheel brakes (EMBs), which are also intended for use as service brakes. These wheel brakes offer several advantages over conventional, hydraulically actuated wheel brakes. For example, a complex hydraulic system is no longer required, and an electromechanical wheel brake is also significantly more compact.

[0003] These electromechanical wheel brakes typically have an electronic drive unit, also known as a brake actuator, which interacts with a mechanism or gearbox. On the output side, a brake unit can be arranged, which may include, for example, a brake piston and a friction lining that can be pressed against a rotating friction partner, such as a brake disc, by means of a translational movement. This results in deceleration during operation.

[0004] The drive unit typically includes at least one electric motor with a correspondingly high power density. Brushless electric motors are increasingly being used for this purpose. The mechanical connection to the friction brake can then be established via at least the gearbox, whereby suitable mechanisms are known for converting the rotational motion of the electric motor into the required translational or linear motion, for example, ball screws as rotational / translational converters.

[0005] A control unit, which may include corresponding force regulators, is generally provided to control the electric motor. Based on a predefined target force, which may correspond to a driver's braking request, the force regulator can generate a target value for the actuator speed or rotational speed in a known manner in order to set this target force as quickly as possible. In this way, the application of the clamping force in the clamping direction of the electromechanical vehicle brake can be achieved. The braking systems of a motor vehicle are among the safety-relevant systems that must be brought into a safe operating state in the event of a dangerous malfunction.

[0006] In some applications with electronically controlled brushless electric motors, a safe system state is achieved, for example, by actively driving the electric motor into a predefined operating state, such as a disengaged state in the case of a gear actuator. However, such an electromechanically actuated brake actuator stores potential energy in the form of a clamping force, especially in the case of a heavily clamped wheel brake. This risk is particularly high with disc brakes, where clamping force can cause deformation of the associated caliper housing, resulting in the build-up of a high clamping force.

[0007] In the event of a control system failure, there is a risk that the electric motor will accelerate sharply backwards due to the stored energy. If the motor speed becomes too high, there is a risk of damage to the wheel brake, for example, if moving or rotating parts of the electric motor collide with fixed stops. Parts of the gearbox or the rotary / translational converter, for instance, could hit an end stop, and the motor (containing the kinetic energy) could generate high forces or torques.

[0008] Alternatively, the system can be brought into a safe operating state using mechanical means, for example by disengaging it with a spring. However, the use of mechanical means such as a spring can be structurally complex and also expensive.

[0009] Therefore, methods for operating a brushless electric motor that do not have the aforementioned disadvantages or at least mitigate them are desirable.

[0010] The inventors have taken on this task.

[0011] This problem is solved surprisingly simply by a method for controlling an electric motor, a circuit arrangement, and an electromechanical braking device for a motor vehicle according to one of the independent claims. Preferred embodiments and further developments of the invention can be found in the respective dependent claims.

[0012] The method can therefore be used to control an electric motor with a suitably designed circuit arrangement. The electric motor can, for example, be used as a force controller for an electromechanical braking system of a motor vehicle.

[0013] The method according to the invention can comprise a control circuit and a separate or largely or completely independent emergency circuit arrangement.

[0014] The procedure may include the following steps, preferably in the order shown: - in a normal operating mode the electric motor is controlled by the control circuit, - where operating values ​​of the electric motor are recorded by the control circuit, - whereby an emergency stop program is selected by the control circuit based on the operating values, and - whereby, in the event of a failure of the control circuit, the control of the electric motor is taken over by the emergency switching arrangement based on the selected emergency stop program.

[0015] The method according to the invention makes it possible to bring an electric motor into a safe operating state when the control by the provided control circuit no longer functions fully or even fails completely. A safe operating state can be defined as a state of the electric motor in which a predetermined speed is no longer exceeded or the electric motor has reached a standstill position.

[0016] The method according to the invention can increase or ensure the protection of the actuator and the components of the electric motor. This is particularly advantageous in cases where an additional force component acts on the brushless electric motor at the time when the control circuit fails, for example, due to a power failure.

[0017] The additional force component can be, for example, a clamping force when the electric motor is used as a pressure regulator in an electromechanical braking system of a motor vehicle and the associated wheel brake is tightly clamped. For instance, tight clamping of a disc brake can lead to deformation of the associated caliper housing, thereby storing this clamping force. Releasing such a clamped electromechanical wheel brake can damage components or end stops, as this clamping force can have an additive effect during release. The present invention thus enables effective component protection, such as for the end stops or gear components, and / or a reduction in release time.

[0018] The invention therefore aims to achieve the shortest possible self-opening time of the electromechanical wheel brake in the event of a failure of the associated control circuitry. In this way, uncontrolled, prolonged, and unbraked self-opening of the actuator can be avoided.

[0019] The electric motor can, for example, comprise an electronically commutated permanent magnet synchronous machine or a brushless electric motor. Such electric motors can include a stator with at least two, preferably three, phase windings and a rotor with at least one pole pair arranged perpendicular to the axis of rotation, formed by one or more permanent magnets arranged in or on the rotor. Each phase winding can be assigned a half-bridge, which can be supplied with a voltage. In a three-phase brushless electric motor, three such half-bridges can form a so-called B6 bridge, which acts as an inverter. When one or more phase windings are energized, the rotor aligns itself accordingly in the resulting magnetic field.

[0020] The electric motor can be powered via the control circuit in a known manner. The control circuit can include a microcontroller with suitable processor and memory capabilities. The microcontroller can include a pulse-width modulation module to operate the electric motor using pulse-width modulation. The control circuit can also include a driver circuit, for example, in the form of a gate driver unit (GDU). The B6 bridge can be controlled via the driver circuit, thereby enabling the operation of the electric motor.

[0021] For regular operation of the electric motor, a normal operating mode can be provided, in which the electric motor is controlled by the control circuit. Normal operation thus represents an unrestricted operating mode in which, in particular, a correct voltage supply to the control circuit is ensured and the control circuit functions fully. The control circuit can therefore have a voltage supply, which can be understood as a voltage that provides the electric motor with electrical energy. The control circuit can thus be supplied by a primary voltage source. This primary voltage source can be the vehicle's electrical system.

[0022] According to the invention, an emergency switching arrangement can also be provided. The emergency switching arrangement can particularly preferably be configured to control the half-bridges or the inverter. Accordingly, the emergency switching arrangement can include those functions that make it possible to control the inverter.

[0023] According to a preferred embodiment of the invention, the emergency switching arrangement is configured to take over the control of the electric motor when regular operation of the electric motor via the control circuit is not possible, for example, due to a failure of the power supply to the control circuit. The emergency switching arrangement can therefore serve to enable emergency operation of the electric motor and preferably to ensure this emergency operation until a safe operating state of the electric motor is reached. The emergency switching arrangement can take over the control of the electric motor at least for a predetermined period of time or until a safe operating state is reached.

[0024] The emergency switching arrangement can be particularly advantageously designed independently and / or separately from the control circuit, so that the inverter can continue to operate in the event of a failure of the regular control circuit, for example, a voltage drop. Separate can mean physically and / or electrically isolated from the control circuit. In this way, the inverter, and thus the electric motor, can continue to operate even if the control circuit fails. This makes it possible to bring the electric motor to a safe operating state even in the event of a voltage drop in the vehicle's electrical system.

[0025] The emergency circuit arrangement can be implemented, for example, as an independent and / or separate processor, microprocessor, or by means of independent and / or separate specific hardware, such as integrated circuits (ASIC), or field-programmable gate arrays (FPGAs) or gate driver units (GDUs).

[0026] According to a preferred embodiment of the invention, the emergency circuit arrangement can have a separate, independent second power supply, separate from the control circuit. For this purpose, according to a particularly preferred embodiment of the invention, the emergency circuit arrangement can be supplied by a separate electrical energy storage device, preferably a battery or a capacitor, whereas the control circuit can be supplied via the vehicle's electrical system. The power supply from the second voltage source can preferably be maintained until the electric motor has reached a safe operating state. Accordingly, it may be sufficient to provide a correspondingly small second voltage source.

[0027] The emergency circuit can have a failure detection feature (“watchdog” function). This allows the emergency circuit to detect a malfunction in the control circuit and take over control of the electric motor.

[0028] According to a preferred embodiment of the invention, the operating values ​​of the electric motor can be detected by the control circuit. This can be done at predetermined times or continuously. The operating values ​​of the electric motor can include at least one of the following quantities: - the speed of the electric motor, - the amount of the current tension force, - Control current of the electric motor.

[0029] The speed of the electric motor can be determined, for example, using a motor position sensor.

[0030] The magnitude of the current clamping force can be determined using a force sensor, provided such a sensor is available. Alternatively, the requested clamping force can be taken into account if, for example, no sensor is provided or no such signal is available.

[0031] The control current of the electric motor can be determined, for example, by measuring the voltage at the driver circuit.

[0032] A particularly preferred embodiment of the invention can provide that the control circuit selects an emergency stop program based on the operating values. This allows the emergency stop program that is optimally suited to the current operating state of the electric motor to be selected. In the event of a failure of the control circuit, the control of the electric motor can then be taken over by the emergency switching arrangement based on the selected emergency stop program.

[0033] In this way, if the control circuit fails, an emergency operation of the electric motor can be initiated promptly to achieve a safe operating state, based on the operating state prior to the failure. This ensures the best possible transition of the electric motor to a safe operating state, starting from the operating state prevailing at the time of the failure.

[0034] According to one embodiment of the invention, the control circuit can have a memory in which a plurality of emergency stop programs are stored. Rules or algorithms can be implemented in the control circuit that, based on the current operating parameters, select the most suitable emergency stop program from the memory in order to bring the electric motor to a safe operating state.

[0035] According to one embodiment of the invention, the control circuit can transmit the current emergency stop program to the emergency switching arrangement, so that upon switching, the emergency switching arrangement then directly executes the last transmitted emergency stop program. Accordingly, it can be provided that in the event of a failure of the control circuit, the control of the electric motor is taken over by the emergency switching arrangement based on the last transmitted emergency stop program.

[0036] According to another embodiment of the invention, the emergency circuit arrangement may have its own memory, and several emergency stop programs are already stored in this memory. The control circuit can then transmit only a very brief emergency message to the emergency circuit arrangement regarding the current emergency stop program to be selected in the event of a failure.

[0037] The transfer of the emergency stop program or emergency information from the control circuit to the emergency switching arrangement can preferably take place regularly during operation at short intervals, e.g. at least every 100 ms, preferably at least every 50 ms, or every 20 ms or in even more rapid succession.

[0038] Criteria for selecting the emergency stop program can include, for example, the current clamping force or the current travel distance in the case of an electric motor for an electromechanical braking device. Possible selection criteria include achieving a safe operating state as quickly as possible or minimizing power consumption. Threshold values ​​can also be defined for the operating parameters; if these thresholds are exceeded or fallen below, the corresponding emergency stop program is selected. These threshold values ​​can be predefined and stored in the microcontroller or another memory module, or they can be dynamically determined and / or adjusted during the process.

[0039] The emergency stop program can be configured to create a short circuit, preferably in all motor phases, at least temporarily. This timed short circuit can slow the rotation of the rotor relative to the stator. This can be particularly advantageous if, for example, an additional force component, such as a clamping force due to a tightly applied wheel brake, acts on the rotation, potentially causing the rotation to become very high. During the short circuit, the phase windings can be connected in parallel, thus creating a short circuit. In this way, the brushless electric motor can essentially be put into generator mode, resulting in deceleration.

[0040] According to the invention, the generation of multiple short circuits in succession can be provided, for example in the form of pulses. Suitable pulse sequences or the associated duty cycles, as well as other parameters for generating short circuits, can be stored in the emergency stop programs and selected depending on the respective operating state. The other parameters can, for example, also include the time until the generation of the first short circuit or the number of repetitions.

[0041] According to a further development of the invention, the circuit arrangement can include a phase isolator in each of the motor phases. In its activated state, the emergency circuit arrangement can then control these phase isolators and thus bring the brushless electric motor into a safe operating state. Advantageously, the B6 bridge can be in a state of a permanent active short circuit or be controlled accordingly. The phase isolators then allow for a particularly advantageous controlled interruption or cancellation of the short circuit, for example, at a timed interval, in order to control the electric motor according to the selected emergency stop program.

[0042] In a further aspect, the present invention comprises a circuit arrangement, in particular for controlling an electric motor for an electromechanical braking device of a motor vehicle, wherein the circuit arrangement can be configured to carry out a method as described above.

[0043] Finally, the present invention, in a further aspect, comprises an electromechanical braking device for a motor vehicle, comprising a circuit arrangement as described above.

[0044] The electric motor can be used particularly advantageously for electromechanically actuated wheel brakes of the electromechanical braking system, with possible applications as a parking brake or as a service brake.

[0045] The electromechanically operated wheel brake can be designed as a disc brake or, for example, as a drum brake.

[0046] Further details of the invention will become apparent from the description of the illustrated embodiments and the attached claims.

[0047] The drawings show: Fig. 1 a simplified representation of an embodiment of a circuit arrangement according to the invention, Fig. 2 a further simplified representation of an embodiment of a circuit arrangement according to the invention, Fig. 3 a further simplified representation of an embodiment of a circuit arrangement according to the invention with a phase separator in each motor phase, and Fig. 4 an exemplary representation of parameters of an electric motor controlled according to the invention in an operating situation with a failure.

[0048] For the sake of clarity, in the following detailed description of preferred embodiments, identical reference numerals denote essentially identical parts in or on these embodiments. However, to better illustrate the invention, the preferred embodiments depicted in the figures are not always drawn to scale.

[0049] Fig. Figure 1 shows a simplified representation of an embodiment of a circuit arrangement 20 according to the invention. For the sake of clarity, only the elements of the circuit arrangement 20 relevant to the design of the inventive approach are shown. Fig. Figure 2 shows a further simplified representation of an embodiment of a circuit arrangement according to the invention.

[0050] The circuit arrangement 20 is designed to control an electric motor 24. According to one embodiment of the invention, the electric motor 24 is designed as a pressure regulator for an electromechanical braking system of a motor vehicle.

[0051] The method according to the invention comprises a control circuit 21 and a separate or largely or completely independent emergency switching arrangement 25.

[0052] The method according to the invention provides for the following steps in the sequence shown: - in a normal operating mode the electric motor 24 is controlled by the control circuit, - where operating values ​​of the electric motor 24 are recorded by the control circuit, - wherein, based on the operating values, an emergency stop program 29 is selected by the control circuit 21, and - in the event of a failure of the control circuit 21, the control of the electric motor 24 is taken over by the emergency switching arrangement 25 on the basis of the selected emergency stop program 29.

[0053] The method according to the invention makes it possible to bring the electric motor 24 into a safe operating state if the control or the voltage supply of the control circuit 21 no longer functions fully or even fails completely. A safe operating state is defined as a state of the electric motor 24 in which a predetermined speed is no longer exceeded or the electric motor has reached a predetermined standstill position. The method according to the invention increases or ensures the protection of the actuator and the components of the electric motor 24.

[0054] In this embodiment, the electric motor 24 is designed as an electronically commutated, permanent magnet synchronous machine with a stator having three phase windings and a rotor. A B6 bridge 23 is assigned to the phase windings as an inverter. The electric motor 24 is supplied with current via the control circuit 21. The control circuit 21 comprises a microcontroller with suitable processor and memory components. The microcontroller includes a pulse-width modulation module to operate the electric motor by means of pulse-width modulation. The control circuit 21 also includes a driver circuit 22 or a gate driver unit (GDU) via which the B6 bridge 23 can be controlled. Appropriate electrical connections 28 for current and signal transmission are provided between the control circuit 21 and the driver circuit 22.

[0055] For the regular operation of the brushless electric motor 24, a normal operating mode is provided in which the electric motor 24 is controlled by the control circuit 21. Regular operation thus represents an unrestricted operating mode in which, in particular, a correct voltage supply to the control circuit 21 is ensured and the control circuit 21 functions fully. The control circuit 21 therefore has a voltage supply (in the Fig. (1 not shown), which is understood to be a voltage used to supply the brushless electric motor 24 with electrical energy. The control circuit 21 is therefore supplied by a first voltage source, which in this case comprises the vehicle electrical system of a motor vehicle.

[0056] According to the invention, an emergency switching arrangement 25 is further provided. This emergency switching arrangement 25 is configured to control the electric motor 24. The emergency switching arrangement 25 includes those functions that enable the inverter 23 to be controlled. According to a particularly preferred embodiment of the invention, the emergency switching arrangement 25 includes only those functions that are absolutely necessary for controlling the electric motor 24. This allows the costs for the design of the emergency switching arrangement 25 to be reduced to a minimum.

[0057] The emergency switching arrangement 25 can thus take over the control of the electric motor 24 if regular operation of the electric motor 24 via the control circuit 21 is not possible, for example, due to a failure of the power supply to the control circuit 21. The emergency switching arrangement 25 therefore serves to enable emergency operation of the electric motor 24 and to ensure this emergency operation until a safe operating state is reached. The emergency switching arrangement 25 can take over the control of the electric motor 24 at least for a predetermined period of time, for example, for a duration of one second, or until a safe operating state is reached.

[0058] The in the Fig. 1 and Fig. The emergency circuit arrangement 25 shown in Figure 2 has a separate, independent second power supply, separate from the control circuit 21. For this purpose, the emergency circuit arrangement 25 is connected to a second power source 26. In this embodiment, this is a battery, for example, a lithium battery. The second power source 26 is configured such that the power supply for the emergency circuit arrangement 25 can be maintained until the electric motor 24 has reached the desired safe operating state. The control circuit 21 is powered via the vehicle's electrical system.

[0059] In the illustrated embodiments, the emergency circuit arrangement 25 is designed as an independent and / or separate processor or microprocessor. Other configurations are also conceivable and possible, for example, using independent and / or separate specific hardware, an integrated circuit (ASIC), or as a field-programmable gate array (FPGA) or gate driver unit (GDU).

[0060] It is possible to provide the components of the control circuit 21 and the emergency circuit arrangement 25, for example the processors, in a common control unit, whereby appropriate separation with regard to the respective power supply should be ensured, so that in the event of a failure of the control circuit 21 the emergency circuit arrangement 25 remains functional independently of this via its own power supply 26.

[0061] The control circuit 21 records the operating values ​​of the electric motor 24. This occurs regularly at short intervals. The recorded operating values ​​of the electric motor 24 include: - the speed of the electric motor, - the amount of the current tension force, - Control current of the electric motor.

[0062] The rotational speed of the electric motor 24 is determined by means of a motor position sensor.

[0063] The current clamping force is determined using a force sensor. Alternatively, the requested clamping force can be used if, for example, no sensor is provided or no such signal is available.

[0064] The control current of the electric motor 24 is determined by measuring the voltage at the driver circuit 22.

[0065] Criteria for selecting a suitable emergency stop program include the current clamping force or, in the case of an electric motor 24 for an electromechanical braking device, the current travel distance. Further selection criteria can include achieving a safe operating state as quickly as possible or minimizing power consumption. Threshold values ​​can also be defined for the operating parameters; if these thresholds are exceeded or fallen below, the corresponding emergency stop program is selected. These threshold values ​​can be predefined and stored in the microcontroller or another memory module, or they can be dynamically determined and / or adjusted during the process.For example, a first emergency stop program 29 can be selected if a particularly high clamping force is applied and the electric motor 24 has a high rotational speed, and another, second emergency stop program 29 if the clamping force is lower and / or the rotational speed is lower.

[0066] In the event of a failure of the control circuit, the control of the electric motor 24 can be taken over by the emergency switching arrangement based on the selected emergency stop program. Emergency operation of the electric motor 24 is initiated promptly to achieve a safe operating state, which is determined by the operating state of the electric motor 24 before the failure. This ensures the best possible transition of the electric motor 24 to a safe operating state, starting from the operating state prevailing at the time of the failure.

[0067] For this purpose, the control circuit 21 according to an embodiment of the invention, as described in Fig. Figure 1 shows a memory in which a plurality of emergency stop programs 29 are stored. In which in Fig. In the example shown, three emergency stop programs 29 are shown for illustrative purposes only. Algorithms are implemented in the control circuit 21 which, based on the current operating parameters, select the optimally matching emergency stop program 29 from memory in order to bring the electric motor 24 into a safe operating state. According to this embodiment of the invention, the control circuit 21 regularly transmits the currently selected emergency stop program 29 to the emergency switching arrangement 25, so that upon switching, the emergency switching arrangement 25 then directly executes the last transmitted emergency stop program 29. In the example shown in Fig. In the embodiment shown in Figure 1, the second emergency stop program 29 is currently selected and is being transmitted.

[0068] According to another, in Fig. In the embodiment of the invention shown in Figure 2, the emergency circuit arrangement 25 has its own memory, and several emergency stop programs 29 are already stored in this memory of the emergency circuit arrangement 25. The control circuit 21 can then transmit only a very short emergency message to the emergency circuit arrangement 25 regarding the current emergency stop program to be selected in the event of a failure. In this embodiment, the second ("2") emergency stop program 29 is currently selected.

[0069] According to a further development of the invention, the emergency switching arrangement 25 has a failure detection function (“watchdog” function). In this way, the emergency switching arrangement 25 can detect if a malfunction of the control circuit 21 has occurred, and the control of the electric motor 24 can be transferred to the emergency switching arrangement 25. For control purposes, the last transmitted emergency stop program 29 or the emergency stop program 29 corresponding to the emergency information can be started.

[0070] The transmission of the emergency stop program 29 or the emergency information from the control circuit 21 to the emergency switching arrangement 25 takes place regularly at short intervals, e.g. at least every 100 ms, preferably at least every 50 ms, or every 20 ms or in even more rapid succession.

[0071] The emergency stop program 29 includes a program to create a short circuit, at least temporarily, in the motor phases of the electric motor 24, thereby braking the rotational movement of the rotor relative to the stator. During the short circuit, the phase windings are connected in parallel. In this way, the brushless electric motor 24 can be put into generator mode, resulting in braking.

[0072] According to the invention, the generation of at least one or more successive short circuits is provided, for example in the form of pulses. Various parameters for generating short circuits are stored in the emergency stop program 29. These can include the pulse sequences or the associated duty cycles, the time until the first short circuit is generated, or the number of repetitions. Based on the parameters of the selected emergency stop program 29, the electric motor 24 is controlled by the emergency switching arrangement 25 in emergency operation until a safe operating state is reached.

[0073] According to a further development of the invention, the circuit arrangement 20 comprises a phase isolator 30 in each of the motor phases 31. In an activated state, the emergency circuit arrangement 25 controls the phase isolators 30 and thus brings the electric motor 24 into a safe operating state. Fig. Figure 3 shows a further simplified representation of such a circuit arrangement according to the invention. The emergency stop program 29 enables the control of the phase isolators 30 for regulating the electric motor 24. The B6 bridge 23 is in a state of a permanent active short circuit or is controlled accordingly. In this way, the phase isolators 30 cannot perform a controlled interruption or cancellation of the short circuits, for example, at a timed interval. The timing can be set via the emergency stop program 29 and adapted to the current operating situation of the electric motor 24.

[0074] Fig.Figure 4 shows an exemplary representation of various parameters of a brushless electric motor 24 controlled according to the invention during simulated operation over time. The electric motor 24 is initially controlled such that a predetermined clamping force (“Force”) F1 is reached, as shown in parameter figure a. From this point on, a failure and control via the emergency switching arrangement are simulated in order to bring the electric motor 24 into a safe operating state, in which the clamping force returns to zero.

[0075] The parameter image c shows, for example, the rotational speed, parameter image b the torque, and parameter images d and e the current and voltage curves in the different motor phases.

[0076] In a further aspect, the present invention comprises a circuit arrangement 20, in particular for controlling an electric motor 24 for an electromechanical braking device of a motor vehicle, wherein the circuit arrangement 20 is configured to carry out a method as described above.

[0077] Finally, in a further aspect, the present invention comprises an electromechanical braking device for a motor vehicle, comprising a circuit arrangement 20 as described above.

[0078] The electric motor 24 is used to operate electromechanically actuated wheel brakes of the electromechanical braking system, with possible uses as a parking brake or as a service brake.

[0079] The electromechanically operated wheel brake can be designed as a disc brake or, for example, as a drum brake. Reference symbol list: 20 Circuit arrangement 21 Control circuit 22 Gate driver circuit 23 B6 bridge 24 Electric motor 25 Emergency switching arrangement 26 Voltage source 27 Data line 28 data lines 29 Emergency stop program 30 phase separators 31 Engine phase

Claims

Method for controlling an electric motor (24) with a circuit arrangement (20), in particular for an electromechanical braking device of a motor vehicle, wherein the circuit arrangement (20) comprises a control circuit (21) and an emergency circuit arrangement (25), wherein in a normal operating mode the electric motor (24) is controlled by the control circuit (21), wherein operating values ​​of the electric motor (24) are detected by the control circuit (21), wherein an emergency stop program (29) is selected by the control circuit (21) on the basis of the operating values, and wherein in the event of a failure of the control circuit (21) the control of the electric motor (24) is taken over by the emergency circuit arrangement (25) on the basis of the selected emergency stop program (29). Method according to claim 1 above, characterized in that the electric motor (24) comprises an electronically commutated, permanent magnet synchronous machine. Method according to one of the preceding claims, characterized in that the emergency switching arrangement (25) is designed as a circuit independent and / or separate from the control circuit (21). Method according to one of the preceding claims, characterized in that the emergency circuit arrangement (25) is designed as an independent and / or separate processor, in a separate microprocessor, or by means of independent and / or separate specific hardware, such as integrated circuits (ASICs), or field-programmable gate arrangements (FPGAs) or gate driver unit (GDU). Method according to one of the preceding claims, characterized in that the control circuit (21) is supplied by a first voltage source, wherein the first voltage source is preferably the vehicle electrical system of a motor vehicle. Method according to one of the preceding claims, characterized in that the emergency circuit arrangement (25) is supplied by a second voltage source (26) separate from the first voltage source, wherein the second voltage source comprises a separate storage device for electrical energy, preferably a battery or a capacitor. Method according to one of the preceding claims, characterized in that the control circuit (21) has a memory containing emergency stop programs (29) stored therein, and wherein the currently selected emergency stop program (29) is regularly transferred to the emergency switching arrangement (25). Method according to one of the preceding claims, characterized in that the emergency circuit arrangement (25) has a memory containing emergency stop programs (29) stored therein, and wherein emergency information relating to the current emergency stop program (29) is transmitted to the emergency circuit arrangement (25). Method according to one of the preceding claims, characterized in that the emergency switching arrangement (25) has a failure detection (“watchdog” function) for detecting a failure of the control circuit (21). Method according to one of the preceding claims, characterized in that the selection of an emergency stop program (29) and / or the transfer from the control circuit (21) to the emergency switching arrangement (25) is carried out continuously, preferably at least every 100 ms, particularly preferably at least every 50 ms, or every 20 ms. Method according to one of the preceding claims, characterized in that the emergency stop program (29) includes at least temporarily generating a short circuit, wherein the phase windings are preferably connected in parallel to each other, and wherein the emergency stop program (29) preferably specifies pulse sequences for generating the short circuits. Method according to one of the preceding claims, characterized in that the circuit arrangement (20) comprises a phase isolator (30) in each of the motor phases (31), and wherein the emergency stop program (29) can control the phase isolators (30), wherein the B6 bridge of the electric motor (24) is preferably in an active short circuit. Method according to one of the preceding claims, characterized in that the operating values ​​of the electric motor (26) include at least one of the following quantities: - the speed of the electric motor (24), - the magnitude of the current clamping force, - the control current of the electric motor (24). Circuit arrangement (20), in particular for controlling an electric motor (24) for an electromechanical braking device of a motor vehicle, designed to carry out a method according to one of the preceding claims. Electromechanical braking device of a motor vehicle, comprising a circuit arrangement (20) according to the preceding claim.

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