Method for operating a device having an electric motor and having a sound module

Abstract

The invention relates to a method for operating a device (2) that has an electric motor (4), a sound module (8) and a first control unit (6a) for generating a PWM signal (Sa, Sb, Sc) for the electric motor (4), wherein voltage reference signals (Ua, Ub, Uc) are determined for the phases of the electric motor (4) and are supplied to the first control unit (6a), wherein a PWM variation signal (SV) is supplied to the first control unit (6a) by the sound module (8) in order to generate noise through vibration of a rotor of the electric motor (4), and wherein the first control unit (6a) generates the PWM signal (Sa, Sb, Sc) for the respective phase of the electric motor (4) on the basis of the voltage reference signals (Ua, Ub, Uc) and the PWM variation signal (SV). The invention furthermore relates to such a device (2).

Description

[0001] Method for operating a device with an electric motor and a sound module

[0002] The invention relates to a method for operating a device comprising an electric motor, a control unit for generating a PWM signal for the electric motor, and a sound module. Furthermore, the invention relates to such a device.

[0003] It is known from the prior art to control an electric motor in such a way that it is set into vibration in order to generate a predetermined noise.

[0004] For example, US 2010 / 0134058 A1 discloses a method and system for operating an automotive electric motor with first and second components. A desired vibration frequency for the electric motor is selected. A current is caused to flow through at least one of the first and second components, causing the second component to move relative to the first component. The current is modulated so that the motor vibrates at the desired frequency.

[0005] Furthermore, EP 3 145 792 B1 describes a method for noise modulation of a three-phase synchronous motor which is driven by a motor control unit using vector control, wherein a current component forming a magnetizing current is adapted to a desired acoustic state as a function of a measured acoustic state.

[0006] WO 2019 / 214777 A1 describes a method for generating and / or compensating vibrations using electrical machines. Actual values ​​for current components are compared with specified reference variables, and the electric motor is controlled by at least one torque-generating current component depending on the operating state of the electric motor to generate and / or compensate vibrations. According to a specified function, a current variable and / or an actual value of a current variable is fed to a feedforward control. The resulting control variables for the torque-generating current components are fed directly to a control unit and then as voltage variables to power electronics and a transformation stage.

[0007] Acoustic warning systems for quiet vehicles, especially electric vehicles, are also known. One such system, known as an Acoustic Vehicle Alert System (AVAS), generates noises similar to those of a combustion engine when the vehicle falls below a prescribed speed, e.g., 20 km / h or 30 km / h, making it easier for pedestrians to hear the vehicle.

[0008] The invention is based on the object of providing an alternative and / or particularly suitable method for operating a device with an electric motor, in which a noise is generated by the electric motor. Furthermore, a corresponding device, a computer program intended for such operation, and a computer-readable medium containing the computer program are to be provided.

[0009] With regard to the method, the object is achieved according to the invention by the features of claim 1. With regard to the device, the object is achieved according to the invention by the features of claim 5, with regard to the computer program by the features of claim 9, and with regard to the computer-readable medium by the features of claim 10. Advantageous embodiments and further developments are the subject of the dependent claims. The statements made in connection with the method also apply mutatis mutandis to the device, to the computer program, and to the computer-readable medium, and vice versa. The method serves to operate a device which has an electric motor, a sound module, and a first control unit. The first control unit is provided and configured to generate PWM signals and to output them to the electric motor, in particular to semiconductor switches in its inverter.The first control unit is or advantageously comprises a PWM generator.

[0010] According to the method, voltage reference signals for the phases of the electric motor are first provided using a motor current controller. The voltage reference signals are then fed to the first control unit to generate the PWM signals for controlling the motor. The motor current is expediently controlled using a second control unit, so the voltage reference signals are provided by the second control unit to the first control unit.

[0011] Furthermore, a PWM variation signal is supplied to the first control unit, in particular directly, from the sound module.

[0012] The first control unit generates the PWM signals for the phases of the electric motor depending on both the voltage reference signals and the PWM variation signal.

[0013] The PWM variation signal is used to control the electric motor (also referred to as the motor) in such a way that its rotor vibrates, preferably a rotary vibration. This vibration results in the generation and emission of a corresponding noise from the electric motor.

[0014] In summary, the method involves exciting the electric motor, in particular its rotor, to vibrate, in particular rotate. The method is therefore used to generate a noise using the electric motor. The noise is preferably an acoustic noise that can be perceived by a person external to the device. To generate the PWM signals, intermediate PWM signals corresponding to the voltage reference signals are preferably first determined. These intermediate PWM signals are then modified, i.e., varied, depending on the PWM variation signal. In particular, the duty cycle is adjusted. Modulation of the intermediate PWM signals thus occurs. The modulation is performed in such a way that the rotor is excited to vibrate in accordance with the PWM variation signal.

[0015] The PWM variation signal is preferably designed such that a predetermined sound, for example a melody or the sound of an internal combustion engine, is generated by the vibration.

[0016] The PWM variation signal contains, for example, information about the frequencies and amplitudes of the noise to be generated, wherein the first control unit varies the PWM intermediate signals such that the noise generated by the vibration of the rotor has these frequencies and amplitudes.

[0017] Alternatively, and preferably, the PWM variation signal directly includes instructions for how the PWM intermediate signals are varied. For example, the PWM variation signal includes values ​​for changing the magnitude of the duty cycle to generate the vibration.

[0018] According to a suitable embodiment, a torque-generating motor current is determined during motor current control and is controlled using a first controller, in particular a PI controller. In addition, a magnetizing current is determined and controlled using a second controller, in particular a PI controller. To determine the magnetizing current and the torque-generating motor current, the phase currents of the electric motor are expediently recorded and transformed into the magnetizing current and the torque-generating motor current using a transformation, in particular a Clarke transformation and / or a Park transformation. The magnetizing current and the torque-generating

[0019] Motor current therefore forms the controlled variable for the respective controller.

[0020] According to a first embodiment, to generate the noise, a first reference variable for regulating the torque-generating motor current is determined based on a first current variation signal output by the motor. In particular, the sum of a predetermined target value for the torque-generating motor current and the first current variation signal is used as the first reference variable.

[0021] Additionally or alternatively, a second reference variable for controlling the magnetizing current is determined based on a second current variation signal output by the sound module. The second reference variable is, in particular, the sum of a predetermined target value for the magnetizing current and the second current variation signal.

[0022] According to a second embodiment, in addition to or alternatively to the first embodiment, the voltage reference signals are determined both as a function of a first voltage component output by the first controller, as a function of a second voltage component output by the second controller, and as a function of a first voltage variation signal and / or a second voltage variation signal. The first voltage variation signal and / or the second voltage variation signal are provided, i.e., output, by the sound module.

[0023] Advantageously, a first sum is formed from the first voltage variation signal and the first voltage component and / or a second sum is formed from the second voltage variation signal and the second voltage component.

[0024] Subsequently, a transformation, in particular an inverse Park transformation and / or an inverse Clarke transformation, of the first voltage component, the second voltage components, the first sum and / or the second sum is expediently carried out to determine the voltage reference signals.

[0025] This advantageously allows the computational effort required by the first and / or second control unit to be influenced. Thus, the generation of the sound is, or can be, divided between the two control units.

[0026] In summary, the first and second designs provide additional intervention points for generating the noise.

[0027] According to an advantageous embodiment, the PWM frequency is more than twice the controller clock rate for motor current control. Suitably, the PWM frequency is greater than 10 kHz, for example, greater than 10 kHz and less than or equal to 100 kHz, preferably up to 50 kHz, in particular between 15 kHz and 25 kHz, for example, 20 kHz. Alternatively or preferably additionally, a controller clock rate for motor current control, in particular the controller clock rate of the first controller and / or the second controller, is less than 2 kHz, in particular between 0.5 kHz and 1.5 kHz, for example, 1 kHz.

[0028] This advantageously allows for the generation of noise at a comparatively high frequency, particularly at a frequency corresponding to half the PWM frequency. In summary, noises can be generated whose frequency is higher than the controller clock rate.

[0029] According to an expedient embodiment of the method, a position signal concerning the position of the rotor is fed to the first control unit. The position signal thus contains information about the rotational position (angular position) of the rotor relative to a reference point, in particular relative to the stator. The PWM signal for at least one of the phases of the electric motor is generated as a function of the position signal. The position of the rotor can thus be taken into account when generating the noise. It is therefore possible to generate the PWM signals in such a way that only predetermined phases are used to generate the noise and / or the predetermined phases are varied at a predetermined (rotational) position or within a predetermined position range, i.e., generated as a function of the PWM variation signal. For the other phases and / or in the other positions, the PWM signals are then generated, for example, solely in accordance with the voltage reference signals.

[0030] Consequently, the influence of noise generation on motor operation can be adjusted, and in particular, minimized. For example, only phase A is varied within a position range of 0° to 10° to generate the noise. Thus, the corresponding excitation always occurs in the same (rotational) direction.

[0031] A further aspect of the invention relates to a device comprising an electric motor, a sound module, and a control and regulation device for carrying out the method in one of the variants described above. In other words, the device comprises the electric motor and means adapted to carry out the steps of the method in one of the variants described above. In particular, the means comprise the sound module and the control and regulation device, which in turn comprises the first control unit.

[0032] The device is therefore operable according to the method and / or is operated according to the method.

[0033] According to an advantageous embodiment of the device, the regulating and control unit comprises the first control unit, which is in particular designed as a PWM generator or comprises such a generator, for generating PWM signals, and a second control unit, which is in particular designed as a p-controller or comprises such a generator, for regulating the motor currents. The first control unit and the second control unit are separate from one another. In other words, the first and second control units are functionally and mechanically separated from one another. The PWM variation signal output by the sound module is therefore not first output to the second control unit and processed there to generate the sound, in particular based on the motor current control, but rather it is output directly to the first control unit (which is close to the motor in terms of control technology).This enables a comparatively fast and / or comparatively low-effort control of the electric motor for noise generation.

[0034] Additionally, this makes it possible to integrate a safety function for the electric motor, in particular for the bridge circuit of its inverter, into a first control unit separate from the second control unit. For example, in the event of a fault in which a motor temperature threshold and / or a motor current threshold are exceeded, the PWM signals can be adjusted directly using the first control unit to reduce the motor current. Consequently, comparatively rapid intervention in the event of a fault is possible, preventing damage to the device.

[0035] According to an advantageous embodiment, the sound module is an AVAS sound module. In other words, the sound module is provided and configured to control the first and / or the second control unit such that a warning noise is generated by the electric motor, wherein the noise preferably corresponds to the noise of an internal combustion engine. The vibration of the rotor is thus adjusted based on the PWM variation signal such that such a noise is generated. Preferably, the first and / or the second control unit is controlled to generate such a noise when a speed value supplied to the sound module, which represents the speed of a motor vehicle having the device, falls below a predetermined threshold value, for example 20 km / h or 30 km / h.

[0036] According to a preferred embodiment, the electric motor is a radiator fan motor for a motor vehicle. When such a radiator fan motor generates noise, its connection to a support device also causes the support device to vibrate. This structure-borne noise is radiated into the air, making the noise particularly audible to passersby.

[0037] The radiator fan motor is used to generate a sound for AVAS applications. This makes it possible to replace at least one speaker of an Acoustic Vehicle Alert System with the device.

[0038] A further aspect of the invention includes a computer program, particularly for the first control unit of the device. This program includes instructions that cause the first control unit to generate the PWM signal as a function of the voltage reference signals transmitted by the second control unit and the PWM variation signal transmitted by the sound module.

[0039] Preferably, the computer program further comprises instructions causing the PWM signal to be generated in dependence on the position signal.

[0040] A further aspect of the invention relates to a computer-readable medium on which the computer program is stored. The computer-readable medium is preferably a non-volatile memory, for example, a flash memory and / or a hard disk. Preferably, the computer-readable medium is a memory of the first control unit.

[0041] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The single figure shows a schematic block diagram of a device comprising an electric motor, a sound module, and a control and regulation device with a first and a second control unit.

[0042] The device 2 has an electric motor 4. This is preferably a radiator fan motor for a motor vehicle, in particular an electrically powered one. The electric motor 4 comprises, in a manner not shown in detail, a rotor and a stator which has a stator winding with a number of phases a, b, c, here for example three. The electric motor 4 further comprises an inverter which is connected to a DC voltage source (not shown). The inverter comprises a bridge circuit with switches, in particular semiconductor switches. To generate and adjust a (phase) current 1a, 1b, 1c through the respective phase a, b, c of the electric motor, the semiconductor switches of the electric motor 4 are controlled using PWM signals Sa, Sb, Sc. The PWM signals Sa, Sb, Sc are provided by a first control unit 6a and transmitted to the electric motor 4.The frequency of the PWM signals is preferably greater than 10 kHz and / or less than 150 kHz.

[0043] The device 2 further comprises a sound module 8. The sound module 8 is an AVAS sound module. This is intended and configured to control the first control unit 6a and / or the second control unit 6b such that a warning sound is generated by the electric motor 4 through the rotational vibration of its rotor, wherein the sound preferably corresponds to the sound of an internal combustion engine.

[0044] For this purpose, the sound module 8 is directly connected to the first control device 6a for signal and / or data transmission, so that a PWM variation signal Sv can be transmitted from the sound module 8 to the first control device 6a. To generate a sound, the first control device 6a is supplied with voltage reference signals 11a, 11b, Uc from a second control device 6b, which, as described further below, is provided in particular for motor current control, as well as with the PWM variation signal Sv from the sound module 8. The first control unit 6a generates the PWM signals Sa, Sb, Sc for the electric motor as a function of the voltage reference signals 11a, 11b, Uc and the PWM variation signal Sv.

[0045] For example, PWM intermediate signals are first determined in a known manner based on the voltage reference signals Ua, Ub, Uc. In other words, PWM signals for controlling the electric motor 4 are determined as PWM intermediate signals based on the voltage reference signals Ua, Ub, Uc. These PWM intermediate signals are then modified depending on the PWM variation signal. In particular, the duty cycle (duty factor) is adjusted in such a way that the rotor is set into a corresponding vibration to emit a predetermined noise.

[0046] A computer program 12 is stored on a computer-readable medium embodied as memory 10. This program comprises instructions which, according to the embodiments described above, cause the PWM signals Sa, Sb, Sc to be generated by the first control unit 6a as a function of the voltage reference signals 11a, Ub, Uc and as a function of the PWM variation signal Sv.

[0047] The device 2 further comprises a current sensor 14, by means of which the phase currents Ia, Ib, and Ic of the phases of the electric motor 4 are measured, i.e., recorded. The current sensor 14 is connected to the second control unit 6b via signal and / or data transmission. The measured values ​​of the current sensor 14 for the phase currents Ia, Ib, and Ic are fed to a first transformation unit 16 of the second control unit 6b.

[0048] Using the transformation unit 16, a Clark transformation of the supplied measured values ​​of the phase currents Ia, Ib, and Ic is performed, as well as a Park transformation of the result of the Clarke transformation. For the Park transformation, a (rotational angle) position p of the rotor provided by a rotor position sensor 18 of the device 2 is used. The first transformation unit 16 provides the current torque-generating motor current Iq st and the current magnetizing current Id as the result of these transformations.

[0049] For motor current control, i.e. for controlling the torque-generating motor current Iq st and for controlling the magnetizing current Id, the second control unit 6b has a controller, namely a first controller 20, designed here as a PI controller by way of example, and a second controller 22, designed here as a PI controller by way of example. A controller clock cycle of the first and / or the second controller is, for example, less than 2 kHz, suitably selected between 0.5 kHz and 1.5 kHz. At most, the controller clock cycle is less than half the PWM frequency. For controlling the current torque-generating motor current Iq st, a difference is formed between a first reference variable and the actual value of the torque-generating motor current Iq st. This difference is fed to the first controller 20 as a control difference. The reference variable here is a setpoint value Iq.soii is specified for the torque-generating motor current Iq st, which is intended for the operation of the electric motor (without noise generation).

[0050] To control the current magnetizing current Idjst, a difference is calculated between a second reference variable and the actual value of the magnetizing current Idjst. This difference is fed to the second controller 22 as a control difference. The reference variable is a setpoint value Id.soii for the magnetizing current Idjst, which is intended for operating the electric motor (without generating noise).

[0051] Optionally, a first current variation signal l is used to generate the sound from the sound module. q ,v and / or a second current variation signal ld,v is output to the second control unit 6b. In this case, the first command variable is determined based on a sum of the setpoint value Iq.soii and the first current variation signal l q , vformed, and / or the second command variable is formed from a sum of the setpoint value Id,son and the second current variation signal ld,v.

[0052] Based on such a variation of the first and / or second reference variable, the rotor of the electric motor 4 can and / or is excited to vibrate accordingly.

[0053] As a result of the motor current control, the first controller 20 outputs a first voltage component llq and the second controller 22 outputs a second voltage component Lid. These two voltage components U q, Lid are fed as the first and second input variables, respectively, to a second transformation unit 24. Using the second transformation unit 24, an inverse Park transformation of these two voltage components Uq, Ud is performed, followed by an inverse Clarke transformation of the result of the inverse Park transformation. On the output side, the second transformation unit 24 provides the voltage reference signals 11a, Ub, Uc and / or outputs them to the first control unit 6a.

[0054] Optionally, the sound module 8 can send a first voltage variation signal U q ,v for the first voltage component U q and / or a second voltage variation signal (Ud,v) for the second voltage component Lid is output to the second control unit 6b. In this case, the first input variable is changed by adding to the first voltage component U q the first voltage variation signal U q,v is added, and / or the second input variable is changed by adding the second voltage component Ld of the second voltage variation signal Ud,v to the second voltage component Ld. The possibly changed first input variable and the possibly changed second input variable are fed to the input side of the second transformation unit 24.

[0055] In summary, in this optional case, the voltage reference signals lla, Ub, U) are determined depending on the first voltage component U q , the second voltage component Ud and as a function of the first voltage variation signal Ud,v and / or the second voltage variation signal U q ,v determined.

[0056] Based on such a change in at least one of the input variables of the second transformation unit 24, the rotor of the electric motor 4 can and / or is excited to vibrate accordingly.

[0057] In summary, the second control unit 6b is intended to control the motor currents.

[0058] Optionally, the determined position p is fed to the first control unit 6a, wherein the respective PWM signal Sa, Sb, Sc is generated depending on the position. In particular, the PWM intermediate signals are varied, particularly depending on the position for generating the sound. Thus, a variation of the PWM intermediate signals occurs, for example, only for a predefined range of the position p. The first and second control units 6a and 6b are collectively referred to as the regulating and control device 6. However, the first and second control units are separate devices from one another. In this way, a sound can be output comparatively quickly by the sound module through a control process of the first control unit.

[0059] Furthermore, a safety function for the electric motor 4 is integrated into the first control unit. For this purpose, the measured values ​​of the phase currents 1a, 1b, 1c and / or a temperature value ST of the motor temperature detected by a temperature sensor 26 are fed to the first control unit 6a. If a corresponding temperature threshold of the motor temperature and / or a corresponding current threshold is exceeded, the motor current can be reduced comparatively quickly by generating the PWM signals accordingly by the separate first control unit 6a.

[0060] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can be derived from them by those skilled in the art within the scope of the claims without departing from the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiments and / or in the claims can also be combined with one another in other ways without departing from the subject matter of the invention.

[0061] List of reference symbols

[0062] 2 Device

[0063] 4 electric motor

[0064] 6 Control device

[0065] 6a first control unit

[0066] 6b second control unit

[0067] 8 sound module

[0068] 10 computer-readable medium

[0069] 12 computer program

[0070] 14 Current sensor

[0071] 16 first transformation unit

[0072] 18 Rotor position sensor

[0073] 20,22 regulator

[0074] 24 second transformation unit

[0075] 26 Temperature sensor la, lb, lc Phase current

[0076] Id, is the actual value of the magnetizing current

[0077] Id, son Target value of the magnetizing current ld,v Current variation signal for the magnetizing current

[0078] Iq st Actual value of the torque-generating motor current

[0079] Iq.soii Target value of the torque-generating motor current l q ,v current variation signal for the torque-generating motor current p Position

[0080] Sa, Sb, Sc PWM signal for one phase

[0081] ST temperature value

[0082] Sv PWM variation signal

[0083] Ua, Ub, Uc voltage reference signals

[0084] Lid second voltage component

[0085] Ud,v second voltage variation signal llq first voltage component

[0086] Uq,v first voltage variation signal

Claims

Claims 1 . Method for operating a device (2) which has an electric motor (4), a sound module (8) and a first control unit (6a) for generating a PWM signal (Sa, Sb, Sc) for the respective phase of the electric motor (4), wherein voltage reference signals (11a, Ub, Uc) for the phases of the electric motor (4) are determined using a motor current control and are fed to the first control unit (6a), wherein a PWM variation signal (Sv) is fed to the first control unit (6a) for generating a noise by vibration of a rotor of the electric motor (4), in particular directly, from the sound module (8), wherein the first control unit (6a) generates the PWM signals (Sa, Sb, Sc) for the phases of the electric motor (4) as a function of the voltage reference signals (11a, Ub, Uc) and the PWM variation signal (Sv).

2. Method according to claim 1, characterized in that a torque-forming motor current (Iq st) is determined and regulated by means of a first controller (20), and that a magnetizing current (Id, ist) is determined and regulated by means of a second controller (22), wherein a first reference variable for the regulation of the torque-forming motor current (Iq st) is determined by means of a first current variation signal (l q , v ), and / or wherein a second reference variable for regulating the magnetizing current (Id, ist) is determined on the basis of a second current variation signal (ld,v) output by the sound module (8), and / or wherein the first controller (20) has a first voltage component (U q ) and the second controller (22) outputs a second voltage component (Ud), wherein the voltage reference signals (Ua, Ub, Uc) are dependent on the first Voltage component (U q), the second voltage component (Lid) and in dependence on a first voltage variation signal (U q ,v) for the first voltage component (Ud,v) and / or a second voltage variation signal (Ud,v) output by the sound module (8) for the second voltage component (U q ) can be determined.

3. Method according to claim 1 or 2, characterized in that the PWM frequency is more than twice a controller clock cycle for the current control.

4. Method according to one of claims 1 to 3, characterized in that a position signal (p) about the position of a rotor is supplied to the first control unit (6a), and that the PWM signal (Sa, Sb, Sc) is generated as a function of the position signal (p).

5. Device (2) comprising an electric motor (4), a sound module (8) and a control and regulating device (6) for carrying out the method according to one of claims 1 to 4.

6. Device (2) according to claim 5, characterized in that the control device (6) has the first control unit (6a) for generating the PWM signal (Sa, Sb, Sc), and a separate second control unit (6b) for regulating the motor currents (Id, lq).

7. Device (2) according to claim 5 or 6, characterized in that the sound module (8) is an AVAS sound module.

8. Device (2) according to one of claims 5 to 7, characterized in that the electric motor (4) is a radiator fan motor for a motor vehicle.

9. Computer program (12) comprising instructions that cause the first Control unit (6a) of the device (2) according to one of claims 5 to 8, the PWM signal (Sa, Sb, Sc) generates as a function of the voltage reference signals (lla, Ub, Uc) transmitted by the second control unit (6b) and the PWM variation signal (Sv) transmitted by the sound module (8).

10. A computer-readable medium (10) on which the computer program (12) according to claim 9 is stored.

Images