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

Abstract

The invention relates to a method for operating a device (2) comprising an electric motor (4), a sound module (8) and a first control unit (6a) for generating a PWM signal (S a , S b , S c ) for the electric motor (4) has, wherein voltage reference signals (U a , U b , U c ) for the phases of the electric motor (4), and these are supplied to the first control unit (6a), wherein a PWM variation signal (Sv) is supplied to the first control unit (6a) from the sound module (8) to generate a noise by vibration of a rotor of the electric motor (4), and wherein the first control unit (6a) is determined as a function of the voltage reference signals (U a , U b , U c ) and the PWM variation signal (Sv) the PWM signal (S a , S b , S c) for the respective phase of the electric motor (4). Furthermore, the invention relates to such a device (2).

Description

[0001] 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. The invention further relates to such a device.

[0002] It is known from the prior art to control an electric motor in such a way that it is set into vibration to generate a predetermined noise.

[0003] For example, US Patent 2010 / 0134058 A1 discloses a method and a system for operating a motor vehicle 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, such that the second component moves relative to the first component. The current is modulated so that the motor vibrates at the desired frequency.

[0004] Furthermore, EP 3 145 792 B1 describes a method for noise modulation of a three-phase synchronous motor which is driven using vector control by means of a motor control unit, wherein a magnetizing current component is adapted to a desired acoustic state depending on a measured acoustic state.

[0005] WO 2019 / 214777 A1 describes a method for generating and / or compensating vibrations using electric machines. Actual values ​​of current components are compared with predefined reference values, 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 for vibrations. According to a predefined function, a current value and / or an actual value of a current value is fed to a feedforward control system. The resulting control variables are fed directly to a control unit for the torque-generating current components and then, as voltage values, to a power electronics and transformation stage.

[0006] Furthermore, acoustic warning systems are known for low-noise vehicles, especially for electrically powered vehicles. Such a system, known as Acoustic Vehicle Alert System (AVAS), generates a sound similar to that of an internal combustion engine when the vehicle falls below a prescribed speed, e.g., 20 km / h or 30 km / h, so that pedestrians can more easily detect the vehicle acoustically.

[0007] The invention is based on the objective of providing an alternative and / or particularly suitable method for operating a device with an electric motor, in which a noise is generated by means of 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.

[0008] With regard to the method, the problem is solved according to the invention by the features of claim 1. With regard to the apparatus, the problem is solved 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 descriptions relating to the method apply mutatis mutandis to the apparatus, the computer program, and the computer-readable medium, and vice versa.

[0009] The method serves to operate a device comprising an electric motor, a sound module, and a first control unit. The first control unit is designed and configured to generate PWM signals and output them to the electric motor, specifically to semiconductor switches and its inverter. The first control unit is, or expediently includes, a PWM generator.

[0010] The procedure begins with the provision of voltage reference signals for the phases of the electric motor using motor current control. These voltage reference signals are then fed to the first control unit to generate the PWM signals for controlling the motor. Advantageously, the motor current control is performed by a second control unit, meaning the voltage reference signals are provided to the first control unit by the second 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 simply as a motor, in such a way that its rotor vibrates, preferably a rotational vibration. This vibration results in the generation and emission of a corresponding noise from the electric motor.

[0014] In summary, the process involves exciting the electric motor, in particular its rotor, to vibrate, especially to vibrate rotationally.

[0015] The method thus serves to generate a noise using an electric motor. The noise is preferably an acoustic noise perceptible to a person outside the device.

[0016] Preferably, intermediate PWM signals corresponding to the voltage reference signals are first determined to generate the PWM signals. These intermediate PWM signals are then modified, or varied, depending on the PWM variation signal. In particular, the duty cycle is adjusted. Thus, the intermediate PWM signals are modulated. This modulation is such that the rotor is excited to vibrate according to the PWM variation signal.

[0017] 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.

[0018] The PWM variation signal contains, for example, information about the frequencies and amplitudes of the noise to be generated, with the first control unit varying the PWM intermediate signals in such a way that the noise generated by the vibration of the rotor has these frequencies and amplitudes.

[0019] Alternatively, and preferably, the PWM variation signal directly includes instructions on how to vary the intermediate PWM signals. For example, the PWM variation signal here includes values ​​for changing the magnitude of the duty cycle to generate the vibration.

[0020] In a suitable embodiment, the motor current control system determines a torque-generating motor current and regulates it using a first controller, particularly a PL controller. Additionally, a magnetizing current is determined and regulated using a second controller, also particularly a PL controller. To determine the magnetizing current and the torque-generating motor current, the phase currents of the electric motor are advantageously measured and transformed into the magnetizing current and the torque-generating motor current using a transformation, particularly a Clarke transformation and / or a Park transformation. The magnetizing current and the torque-generating motor current thus constitute the controlled variable for the respective controller.

[0021] According to a first embodiment, a first control variable for regulating the torque-generating motor current is determined based on a first current variation signal output by the system to generate the noise. In particular, the sum of a predefined setpoint value for the torque-generating motor current and the first current variation signal is used as the first control variable.

[0022] Additionally or alternatively, a second control variable for the magnetizing current is determined based on a second current variation signal output by the sound module. Specifically, the second control variable is the sum of a predefined setpoint for the magnetizing current and the second current variation signal.

[0023] According to a second embodiment, in addition to or as an alternative to the first embodiment, the voltage reference signals are determined 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.

[0024] It is advantageous to form a first sum from the first voltage variation signal and the first voltage component and / or a second sum from the second voltage variation signal and the second voltage component.

[0025] Subsequently, to determine the voltage reference signals, a transformation is appropriately carried out, 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.

[0026] In this way, it is advantageous to be able to influence the computational effort required for generating the noise by the first and / or second control unit. Thus, the generation of the noise is distributed, or can be distributed, between the two control units.

[0027] In summary, both the first and second designs provide additional points of intervention for generating the noise.

[0028] According to an advantageous embodiment, the PWM frequency is more than twice the controller clock frequency for motor current control. Suitablely, 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, particularly between 15 kHz and 25 kHz, for example, 20 kHz. Alternatively, or preferably additionally, a controller clock frequency for motor current control, in particular the controller clock frequency of the first controller and / or the second controller, is less than 2 kHz, particularly between 0.5 kHz and 1.5 kHz, for example, 1 kHz.

[0029] This method is advantageous for generating noise with a comparatively high frequency, particularly a frequency equal to half the PWM frequency. In summary, noise can be generated with a frequency higher than the controller clock.

[0030] According to a suitable embodiment of the method, a position signal indicating the rotor's position is supplied to the first control unit. This position signal thus contains information about the rotor's rotational position (angular position) relative to a reference point, particularly the stator. The PWM signal for at least one of the electric motor's phases is generated based on this position signal. The rotor's position can therefore be taken into account when generating the noise.

[0031] This allows the PWM signals to be generated in such a way that only predetermined phases are used to produce the noise, and / or the predetermined phases are varied at a given (rotary) position or within a given position range, i.e., generated depending on the PWM variation signal. The other phases and / or in the other positions are then generated, for example, only according to the voltage reference signals.

[0032] Consequently, the influence of noise generation on motor operation can be adjusted, and in particular minimized. For example, if only phase A is varied within a position range of 0° to 10° for noise generation, the corresponding excitation always occurs in the same (rotational) direction.

[0033] Another aspect of the invention relates to a device comprising an electric motor, a sound module, and a control unit 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 perform the steps of the method in one of the variants described above. In particular, the means include the sound module and the control unit, which in turn comprises the first control unit.

[0034] The device is therefore operable according to the method and / or is operated according to the method.

[0035] According to an advantageous embodiment of the device, the control unit comprises a first control unit for generating PWM signals, which is in particular designed as or comprising a PWM generator, and a second control unit for regulating the motor currents, which is in particular designed as or comprising a microcontroller. The first and second control units are separate from each other. In other words, the first and second control units are functionally and mechanically separated.

[0036] The PWM variation signal output by the sound module is therefore not first sent to the second control unit and processed there to generate the sound, particularly by means of motor current control, but is sent directly to the first control unit (which is located close to the motor in terms of control technology). This results in a comparatively fast and / or relatively low-effort control of the electric motor for sound generation.

[0037] Additionally, this approach allows a safety function for the electric motor, particularly for the bridge circuit of its inverter, to be integrated into a separate first control unit. For example, in the event of a fault where a motor temperature threshold and / or a motor current threshold is exceeded, the PWM signals can be adjusted directly by the first control unit to reduce the motor current. Consequently, a relatively quick intervention in the event of a fault is possible, and damage to the device is avoided.

[0038] According to an advantageous embodiment, the sound module is an AVAS sound module. In other words, the sound module is designed and configured to control the first and / or the second control unit such that a warning sound is generated by the electric motor, the sound preferably corresponding to the sound of an internal combustion engine. The vibration of the rotor is thus adjusted based on the PWM variation signal to generate such a sound. Preferably, the first and / or the second control unit is activated to generate such a sound when a speed value supplied to the sound module, representing the speed of a motor vehicle equipped with the device, falls below a predetermined threshold, for example, 20 km / h or 30 km / h.

[0039] 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 mounting device also causes the device to vibrate. This structure-borne sound is then radiated into the air, making the noise particularly noticeable to passersby.

[0040] Therefore, the radiator fan motor is used to generate a sound for AVAS applications. Because of this, it is possible to replace at least one loudspeaker of an Acoustic Vehicle Alert System with this device.

[0041] Another aspect of the invention comprises a computer program, in particular for the first control unit of the device. This program includes commands that cause the first control unit to generate the PWM signal depending on the voltage reference signals transmitted by the second control unit and the PWM variation signal transmitted by the sound module.

[0042] Preferably, the computer program also includes instructions that cause the PWM signal to be generated depending on the position signal.

[0043] Another 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, flash memory and / or a hard drive. Preferably, the computer-readable medium is a memory of the first control unit.

[0044] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The single figure in the drawing schematically shows a block diagram of a device comprising an electric motor, a sound module, and a control unit with a first and a second control unit.

[0045] The device 2 comprises an electric motor 4. This is preferably a radiator fan motor for a motor vehicle, particularly an electrically powered one. The electric motor 4 includes, 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 a switch, in particular semiconductor switches. For generating and adjusting a (phase) current I a, I b , I c The semiconductor switches of the electric motor 4 are controlled by the respective phases a, b, c of the electric motor using PWM signals S a , S b , S c controlled. The PWM signals S a , S b , S c 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.

[0046] The device 2 further comprises a sound module 8. The sound module 8 is an AVAS sound module. This module is designed and configured to control the first control unit 6a and / or the second control unit 6b in such a way that a warning sound is generated by the electric motor 4 through rotary vibration of its rotor, the sound preferably corresponding to the sound of an internal combustion engine.

[0047] For this purpose, the sound module 8 is directly connected to the first control unit 6a via signal and / or data transmission, so that a PWM variation signal Sv can be transmitted from the sound module 8 to the first control unit 6a. To generate a sound, the first control unit 6a receives voltage reference signals Ua, Ub, Uc from a second control unit 6b, which, as described below, is primarily intended for motor current control, as well as the PWM variation signal Sv from the sound module 8. The first control unit 6a generates the PWM signals S a , S b , S c for the electric motor depending on the voltage reference signals Ua, Ub, Uc and the PWM variation signal Sv.

[0048] For example, intermediate PWM 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 according to the voltage reference signals Ua, Ub, Uc. These intermediate PWM signals are then modified depending on the PWM variation signal. In particular, the duty cycle is adjusted so that the rotor is set into a corresponding vibration to produce a predefined sound.

[0049] A computer program 12 is stored on a computer-readable medium configured as memory 10. This program comprises instructions which, according to the explanations above, cause the PWM signals S to a , S b , S c depending on the voltage reference signals U a , U b , U cand are generated depending on the PWM variation signal Sv using the first control unit 6a.

[0050] The device 2 further comprises a current sensor 14, which measures, i.e., detects, the phase currents 1a, 1b, and 1c of the phases of the electric motor 4. 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 1a, 1b, and 1c are supplied to a first transformation unit 16 of the second control unit 6b.

[0051] The transformation unit 16 performs a Clark transformation on the supplied measured values ​​of the phase currents 1a, 1b, and 1c, as well as a Park transformation of the result of the Clark transformation. For the Park transformation, a (rotational, angular) position p of the rotor, provided by a rotor position sensor 18 of the device 2, is used. The first transformation unit 16 represents the current torque-generating motor current I. q,ist as well as the current magnetization current I d,ist as a result of these transformations.

[0052] For motor current control, i.e., for the control of the torque-generating motor current I q,ist and for the regulation of the magnetizing current I d,istThe second control unit 6b has one controller each, namely a first controller 20, implemented here as an example PL controller, and a second controller 22, implemented here as an example PI controller. The clock frequency of the first and / or the second controller is, for example, less than 2 kHz, preferably chosen between 0.5 kHz and 1.5 kHz. At most, the clock frequency is less than half the PWM frequency.

[0053] For the control of the current torque-generating motor current I q,ist A difference is calculated between a first reference variable and the actual value of the torque-generating motor current I. q,ist This difference is calculated and fed to the first controller 20 as the control error. The reference input here is a setpoint I. q,soll for the torque-generating motor current I q,ist specified which is intended for the operation of the electric motor (without noise generation).

[0054] For the control of the current magnetizing current I d,ist A difference is calculated between a second reference variable and the actual value of the magnetizing current I. d,ist This difference is calculated and fed to the second controller 22 as a control error. The reference input here is a setpoint I. d,soll for the magnetizing current I d,ist specified which is intended for the operation of the electric motor (without noise generation).

[0055] Optionally, a first current variation signal I is used by the sound module to generate the sound. q,v and / or a second current variation signal I d,v output to the second control unit 6b. In this case, the first reference variable is determined based on a sum of the setpoint I. q,soll and the first current variation signal I q,v formed, and / or the second control variable is based on a sum of the target value I d,soll and the second current variation signal I d,v educated.

[0056] Based on such a variation of the first and / or second control variable, the rotor of the electric motor 4 can and / or will be excited to vibrate accordingly.

[0057] As a result of the motor current control, the first controller 20 outputs a first voltage component U q and the second regulator 22 a second voltage component U d out. These two voltage components U q , U d are fed as the first and second input variables, respectively, to a second transformation unit 24. The second transformation unit 24 then performs an inverse Park transformation of these two voltage components U. q , U d and subsequently an inverse Clarke transform of the result of the inverse Park transform. On the output side, the second transformation unit 24 provides the voltage reference signals U. a , U b , U cready and / or outputs this to the first control unit 6a.

[0058] Optionally, a first voltage variation signal U is generated by sound module 8. q,v for the first voltage component U q and / or a second voltage variation signal (U d,v ) for the second voltage component U d output to the second control unit 6b. In this case, the first input variable is changed by adding a voltage component U to the first voltage component. 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 U. d the second voltage variation signal U d,v The first input variable, possibly modified, and the second input variable, if any, are added together and fed into the second transformation unit 24.

[0059] In summary, in this optional case, the voltage reference signals U a , U b , U) as a function of the first voltage component U q , the second voltage component U d as well as depending on the first voltage variation signal U d,v and / or the second voltage variation signal U q,v certainly.

[0060] 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 will be excited to vibrate accordingly.

[0061] In summary, the second control unit 6b is intended for regulating the motor currents.

[0062] Optionally, the determined position p is supplied to the first control unit 6a, with the respective PWM signal S a , S b , S cThe noise is generated depending on the position. In particular, the PWM intermediate signals are varied, especially depending on the position, to generate the noise. For example, the variation of the PWM intermediate signals only occurs for a predefined range of position p.

[0063] The first and second control units 6a and 6b are collectively referred to as the control and regulation unit 6. However, the first and second control units are separate devices. In this way, a sound can be output relatively quickly by a control operation of the first control unit via the sound module.

[0064] 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 S detected by a temperature sensor 26 are sent to the first control unit 6a. TThe motor temperature is supplied. If a corresponding temperature threshold of the motor temperature and / or a corresponding current threshold is exceeded, the motor current can be reduced relatively quickly by means of a corresponding generation of PWM signals by the separate first control unit 6a.

[0065] The invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person 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 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. Reference symbol list 2 Device 4 electric motor 6 Control unit 6a first control unit 6b second control unit 8 Sound module 10 computer-readable media 12 Computer program 14 Current sensor 16 first transformation unit 18 Rotor position sensor 20,22 regulator 24 second transformation unit 26 Temperature sensor I a , I b , I c Phase current I d,ist Actual value of the magnetizing current I d,soll Target value of the magnetizing current I d,v Current variation signal for the magnetizing current I q,ist Actual value of the torque-generating motor current I q,soll Target value of the torque-generating motor current I q,v Current variation signal for the torque-generating motor current p position S a , S b , S c PWM signal for one phase S T Temperature value SV PWM variation signal U a , U b , U c Voltage reference signals U d second voltage component U d,v second voltage variation signal U q first voltage component U q,v first voltage variation signal QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2010 / 0134058 A1

[0003] EP 3 145 792 B1

[0004] WO 2019 / 214777 A1

[0005]

Claims

[1] Method for operating a device (2) comprising an electric motor (4), a sound module (8) and a first control unit (6a) for generating a PWM signal (S a , S b , S c ) for the respective phase of the electric motor (4), - where voltage reference signals (U a , U b , U c ) for the phases of the electric motor (4) are determined by means of a motor current control, and these are fed to the first control unit (6a), - wherein the first control unit (6a) is supplied with a PWM variation signal (S V ) is supplied, - wherein the first control unit (6a) is dependent on the voltage reference signals (U a , U b , U c ) and the PWM variation signal (Sv) the PWM signals (S a , S b , S c) for the phases of the electric motor (4). [2] Method according to claim 1, characterized by , - that a torque-generating motor current (I q,ist ) is determined and controlled by a first controller (20), and that a magnetizing current (I d,ist ) and is controlled by means of a second controller (22), - wherein a first reference variable for controlling the torque-generating motor current (I q,ist ) based on a first current variation signal (I q,v ) is determined, and / or wherein a second reference variable for the control of the magnetizing current (I d,ist ) based on a second current variation signal (I d,v ) is determined, and / or - wherein the first regulator (20) has a first voltage component (U q ) and the second regulator (22) a second voltage component (U d ), whereby the voltage reference signals (Ua , U b , U c ) depending on the first voltage component (U q ), the second voltage component (U d ) and in dependence on a first voltage variation signal (U q,v ) for the first voltage component (U d,v ) and / or a second voltage variation signal (U d,v ) for the second voltage component (U q ) can be determined. [3] Method according to claim 1 or 2, characterized by that the PWM frequency is more than twice a controller clock cycle for current control. [4] Method according to one of claims 1 to 3, characterized by that the first control unit (6a) is supplied with a position signal (p) about the position of a rotor, and that the PWM signal (S a , S b , S c ) is generated depending on 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 by that the control device (6) controls the first control unit (6a) for generating the PWM signal (S a , S b , S c ), and a separate second control unit (6b) for regulating the motor currents (I d , I q ). [7] Device (2) according to claim 5 or 6, characterized by that the sound module (8) is an AVAS sound module. [8] Device (2) according to one of claims 5 to 7, characterized by that the electric motor (4) is a radiator fan motor for a motor vehicle. [9] Computer program (12) comprising instructions causing the first control unit (6a) of the device (2) according to one of claims 5 to 8 to generate the PWM signal (S a , Sb , S c ) depending on the voltage reference signals (U a , U b , U c ) and the PWM variation signal (S V ) is generated. [10] A computer-readable medium (10) on which the computer program (12) according to claim 9 is stored.

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