Active sound-generating device using an electric motor

Abstract

This invention discloses an active sound-generating device using an electric motor, for actively generating a desired target sound by controlling a three-phase electric motor installed in a vehicle. The device includes: a target sound generation signal generator configured to select a target sound and generate a current command signal for driving the electric motor to generate the target sound; a current sensor configured to sense the phase current of the electric motor; an electric motor controller configured to generate a voltage command for driving the electric motor based on the current command signal generated by the target sound generation signal generator, the phase current of the electric motor sensed by the current sensor, and the back electromotive force compensation value of the electric motor, and control the driving of the electric motor to generate the target sound; and a radiated noise generator configured to generate the target sound using vibrations generated by the electric motor driven by the electric motor controller.

Description

Technical Field

[0001] The present invention relates to an active sound-generating device using an electric motor, and more particularly to such an active sound-generating device using an electric motor that actively generates a desired sound by controlling a permanent magnet synchronous motor (PMSM). Background Technology

[0002] Recently, vehicles have widely adopted devices that actively generate desired sounds during driving, as if the sound were produced from the exhaust system using a speaker or vibratory actuator. However, this technology is limited by the need for an external amplifier or a separate actuator to control the sound, thus increasing overall cost and weight. Therefore, following current trends, there is a need to develop a technology that generates desired sounds using components installed in the vehicle without adding a separate external amplifier or actuator, thereby reducing vehicle cost and weight. Summary of the Invention

[0003] Therefore, the present invention was proposed in view of the above problems, and the object of the present invention is to provide an active sound generating device for controlling an electric motor installed in a vehicle to actively generate a desired target sound when the vehicle is in motion without the need to add a separate actuator or external amplifier.

[0004] According to one aspect of the invention, the above and other objectives can be achieved by providing an active sound-generating device using an electric motor for actively generating a desired target sound by controlling a three-phase electric motor installed in a vehicle. The device includes: a target sound generation signal generator configured to select a target sound and generate a current command signal for driving the electric motor to generate the target sound; a current sensor configured to sense the phase current of the electric motor; an electric motor controller configured to generate a voltage command for driving the electric motor based on the current command signal generated by the target sound generation signal generator, actual current information of the electric motor sensed by the current sensor, and a back EMF compensation value of the electric motor, and to control the driving of the electric motor to generate the target sound; and a radiated noise generator configured to generate the target sound using vibrations generated by the electric motor driven by the electric motor controller.

[0005] The target sound generation signal generator includes at least one of the following: an axis selector configured to select an axis from the d-axis and q-axis of a motor for controlling the motor to generate a target sound; a target sound selector configured to select a target sound; a command signal generator configured to select a sampling frequency based on the frequency of the selected target sound and generate a command signal for generating the target sound; a digital-to-analog converter configured to convert the digital signal generated by the command signal generator into an analog signal; a low-pass filter configured to remove low-frequency commands from the signal converted by the digital-to-analog converter; and a noise management unit configured to detect whether the signal output from the low-pass filter contains noise, and to adjust the sampling frequency and the gain value of the low-pass filter to reduce noise when noise is detected.

[0006] The motor controller includes at least one of the following: a dq converter configured to convert three-phase current of the motor, measured by a current sensor, into d-axis and q-axis currents; a dq compensator configured to compensate for the back electromotive force of the motor's d-axis and q-axis; a voltage command generator configured to generate a d-axis or q-axis voltage command to drive the motor and generate a target sound based on d-axis and q-axis current command values ​​input from a target sound generation signal generator, actual d-axis and q-axis current values ​​converted by the dq converter, and compensation values ​​via the dq compensator; a dq inverter configured to convert a voltage command signal generated by the voltage command generator into three phases; and a pulse width modulation (PWM) controller configured to control the PWM signal based on the three-phase voltage command signal converted by the dq inverter.

[0007] The device also includes: a position sensor configured to sense the position of the rotor of the motor; and an angular velocity extraction unit configured to extract the angular velocity of the motor based on the sensed rotor position, wherein the dq compensator compensates for the back electromotive force of the motor's d-axis and q-axis based on the angular velocity of the motor extracted by the angular velocity extraction unit, the inductance of the d-axis and q-axis, the current command values ​​of the d-axis and q-axis, and the magnetic flux of the motor.

[0008] The PWM controller is either Space Vector Pulse Width Modulation (SVPWM) or Sinusoidal Pulse Width Modulation (SPWM).

[0009] The device also includes an inverter comprising multiple switching devices and configured to turn the switching devices on / off according to a PWM signal output from a PWM controller to provide alternating current (AC) to the motor, thereby driving the motor.

[0010] An electric motor is a motor-driven power steering system (MDPS) that is connected to the shaft of the steering wheel installed in a vehicle and assists in steering.

[0011] The radiated noise generator includes: a mounting bracket configured to fix the shaft of the electric motor and the steering wheel; a body including one or more radiated noise generating plates configured to generate radiated noise using vibrations generated by the electric motor; and one or more stiffness adjustment ribs contained in the radiated noise generating plates and configured to adjust the stiffness of the radiated noise generating plates to adjust the natural frequency of the radiated noise generating plates.

[0012] The radiated noise generator also includes one or more mass adjustment holes formed in one or more radiated noise generating plates, and adjusts the mass of the one or more radiated noise generating plates to adjust the natural frequency of the one or more radiated noise generating plates.

[0013] The thickness of one or more radiated noise generating plates is less than the thickness of the mounting bracket.

[0014] One or more radiated noise generating panels can be made of plastic or metal materials. Attached Figure Description

[0015] The above and other objects, features and advantages of the invention will become clearer from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0016] Figure 1 This is a block diagram of the overall structure of an active sound-generating device using an electric motor according to an embodiment of the present invention;

[0017] Figure 2 This is a block diagram illustrating a detailed configuration of a target sound generation signal generator in an active sound-generating device using an electric motor, according to an embodiment of the present invention.

[0018] Figure 3 This is a flowchart illustrating the process of generating a target sound generation signal using a target sound generation signal generator through an active sound-generating device with an electric motor, according to an embodiment of the present invention.

[0019] Figure 4 This is a diagram showing the detailed structure of the motor controller in an active sound-generating device using an electric motor according to an embodiment of the present invention;

[0020] Figure 5 This is a perspective view of a radiated noise generator in an active sound-generating device using an electric motor according to an embodiment of the present invention;

[0021] Figure 6 This is a cross-sectional view of a radiated noise generator in an active sound-generating device using an electric motor according to an embodiment of the present invention;

[0022] Figure 7Experimental results demonstrating noise reduction using a noise management unit in an active sound-generating device with an electric motor, according to an embodiment of the present invention, are shown; and

[0023] Figure 8 The experimental results of examining the target sound generated by an active sound-generating device using an electric motor according to an embodiment of the present invention are shown. Detailed Implementation

[0024] In the following description, exemplary embodiments will be described more fully with reference to the accompanying drawings. The terms or words used herein are not limited to their common or dictionary meanings, but will have meanings corresponding to the technical aspects of embodiments of the invention in order to best express the embodiments of the invention.

[0025] Therefore, the embodiments described in the specification and the configurations shown in the drawings are merely exemplary embodiments of the present invention and do not represent all technical ideas. Thus, it should be understood that various equivalent substitutions have been proposed to replace them at the time of filing this application.

[0026] Figure 1 This is a block diagram of the overall structure of an active sound-generating device using an electric motor according to an embodiment of the present invention. Figure 2 This is a block diagram showing the detailed configuration of the target sound generation signal generator. Figure 3 This is a flowchart illustrating the process of generating a target sound generation signal through a target sound generation signal generator. Figure 4 This is a diagram showing the detailed structure of the motor controller. Figure 5 This is a perspective view of a radiated noise generator. Figure 6 This is a cross-sectional view of a radiated noise generator. Figure 7 The experimental results of the noise management unit reducing noise are shown.

[0027] like Figure 1 As shown, the active sound-generating device using an electric motor according to an embodiment of the present invention can be a device for controlling a three-phase electric motor installed in a vehicle to actively generate a desired target sound, and may include a target sound generation signal generator 100, a current sensor 200, a motor controller 300, an inverter 400, an electric motor 500, and a radiated noise generator 600.

[0028] The target sound generation signal generator 100 can select the target sound to be generated by the drive motor 500, and can generate a current command signal for driving the motor 500 to generate the target sound. Specifically, refer to... Figure 2The target sound generation signal generator 100 may include at least one of the following: axis selector 110, target sound selector 120, command signal generator 130, digital-to-analog converter 140, low-pass filter 150, and noise management unit 160.

[0029] More specifically, axis selector 110 can select the axis to use when the motor 500 is controlled to generate a target sound from the d-axis or q-axis of the motor 500. Here, the d-axis and q-axis of the motor 500 can refer to the axes in the direction of centrifugal force and rotation of the motor 500, or they can refer to the axes obtained by converting the three phases of the (described later) three-phase inverter 400 into two orthogonal coordinate axes to control the motor 500.

[0030] In some embodiments, the q-axis is required to perform the original function of the motor 500 through torque control, so the axis selector 110 can select the d-axis for vibrating and controlling the motor 500 to produce the target sound. However, according to another embodiment, the axis selector 110 can also select the q-axis for vibrating and controlling the motor 500 to produce the target sound.

[0031] When axis selector 110 selects the axis to be used to control motor 500 to generate a target sound, target sound selector 120 can select the target sound generated by the vibration of motor 500. Here, the target sound can use various signals, and in some embodiments, it may include music timing data, a specific frequency, a sine wave formed by coupling multiple specific frequencies, a swept sine wave with varying frequencies, etc. However, this is merely one embodiment, and the target sound is not limited to this.

[0032] When the target sound selector 120 selects a target sound, the command signal generator 130 can select a sampling frequency based on the frequency of the selected target sound and generate a command signal for generating the corresponding target sound. In some embodiments, when the axis selector 110 selects the d-axis to control the motor 500, the command signal generator 130 can generate a d-axis current command signal to generate the corresponding target sound. In another embodiment, when the axis selector 110 selects the q-axis to control the motor 500, the command signal generator 130 can generate a q-axis current command signal for generating the corresponding target sound.

[0033] Specifically, when sampling at a sampling frequency, the instruction signal generator 130 can select a sampling frequency at least five times higher than the frequency of the target sound to be achieved. Here, a sampling frequency at least five times higher than the target sound frequency can be selected for the following reasons: If the selected sampling frequency is too low, the signal cannot properly follow the target sound signal when passing through the digital-to-analog converter 140, the signal waveform will be distorted, and problems will occur in terms of image noise when it is an integer multiple of (sampling frequency ± target sound frequency). Therefore, to overcome this problem, according to the present invention, a sampling frequency at least five times higher than the target sound frequency can be selected.

[0034] The digital-to-analog converter 140 converts the digital signal generated by the command signal generator 130 into an analog signal, and the low-pass filter 150 removes low-frequency components from the signal converted by the digital-to-analog converter 140. The detailed configuration and operating principle of the digital-to-analog converter 140 and the low-pass filter 150 are known technologies, and therefore their detailed description will be omitted.

[0035] The noise management unit 160 can detect whether the signal output from the low-pass filter 150 contains noise, and when noise is detected, the noise management unit 160 can adjust the sampling frequency and the gain value of the low-pass filter 150 to reduce the noise. Specifically, when noise is detected in the signal output from the low-pass filter 150, the noise management unit 160 can further increase the sampling frequency generated by the command signal generator 130 or increase the gain value of the low-pass filter 150 while repeatedly performing the above-mentioned steps. Figure 3 The process is shown until the noise is reduced to a predetermined level. Thus, according to the present invention, when noise is detected in the signal output from the low-pass filter 150, the noise management unit 160 can adjust the sampling frequency and the gain value of the low-pass filter 150 to reduce the noise, thereby outputting a signal as shown. Figure 7 The example shown is a target sound generation command signal with reduced noise. Specifically, refer to... Figure 7 Before applying the noise management unit 160, as shown in the left figure, image noise with a minimum size of 61dB is generated in integer multiples of (sampling frequency ± target sound frequency). However, by applying the noise management unit 160, the image noise can be reduced to a maximum of 31dB, as shown in the right figure.

[0036] The current sensor 200 can sense the current of each phase of the motor 500. The current of each phase sensed by the current sensor 200 can be input to the dq converter 310 and can be converted into d-axis current and q-axis current.

[0037] The motor controller 300 can generate voltage commands for driving the motor 500, and can control the driving of the motor 500 based on the current command signal generated by the target sound generation signal generator 100, the actual current information of the motor 500 sensed by the current sensor 200, and the back EMF compensation value of the motor 500, so as to generate the target sound.

[0038] Specifically, refer to Figure 1 and Figure 4 The motor controller 300 may include at least one of a DQ converter 310, a DQ compensator 320, a voltage command generator 330, a DQ inverse converter 340, and a PWM controller 350. The motor controller 300 may also include a position sensor 360 and an angular velocity extraction unit 370, wherein the position sensor 360 is used to sense the position of the rotor of the motor 500, and the angular velocity extraction unit 370 is used to extract the angular velocity of the motor 500 based on the sensed rotor position. In some embodiments, a Hall sensor, encoder, resolver, etc., may be used as the position sensor 360 for sensing the rotor position.

[0039] More specifically, the dq converter 310 can convert the three-phase current of the motor 500, measured by the current sensor 200, into d-axis and q-axis currents. Phase conversion of the three-phase current of the motor 500 into d-axis and q-axis currents is a known technique, and therefore its detailed description will be omitted.

[0040] The dq compensator 320 can compensate for the back electromotive force of the d-axis and q-axis of the motor 500. Specifically, the dq compensator 320 can compensate for the back electromotive force of the d-axis and q-axis of the motor 500 based on the angular velocity of the motor 500 extracted by the angular velocity extraction unit 370, the inductance of the d-axis and q-axis, the current command values ​​of the d-axis and q-axis, and the magnetic flux of the motor.

[0041] Specifically, the dq compensator 320 can be a conversion compensator, and can compensate for the back electromotive force of the d-axis and q-axis of the motor 500. Here, the dq compensator 320 may include a d-axis compensator 321 and a q-axis compensator 322. More specifically, the compensation values ​​for the back electromotive force of the d-axis and q-axis of the motor 500 can be calculated according to Equation 1 below:

[0042] [Equation 1]

[0043] V d_ref_ff =-ω r L q i q_ref

[0044] V q_ref_ff =ω r (L di d_ref +Ψ pm )

[0045] Here, V d_ref_ff : Voltage command value of d-axis conversion compensator, V q_ref_ff : Voltage command value for the q-axis conversion compensator, ω r Angular velocity of the electric motor, L q L d : Inductance along the q-axis and d-axis, i q_ref 、i d_ref : Current command values ​​for the q-axis and d-axis, Ψ pm : Magnetic flux of an electric motor.

[0046] The voltage command generator 330 can drive the motor 500 and generate a d-axis or q-axis voltage command for generating the target sound based on the d-axis and q-axis current command values ​​input from the target sound generation signal generator 100, the actual d-axis and q-axis current values ​​converted by the dq converter 310, and the compensation value through the dq compensator 320.

[0047] Specifically, the voltage command generator 330 may include proportional-integral controllers 331 and 332 for proportional-integral control of the d-axis and q-axis current command values ​​input from the target sound generation signal generator 100, and the actual d-axis and q-axis current values ​​converted by the dq converter 310. In this case, the voltage command generator 330 may include each of the d-axis and q-axis proportional-integral controllers 331 and 332.

[0048] In addition, such as Figure 4 As shown, in the case of the d-axis, the voltage command generator 330 can input the corresponding value obtained by subtracting the d-axis back EMF compensation value derived by the dq compensator 320 from the output value of the d-axis proportional-integral controller 331 to the RL circuit of the motor 500 to drive the motor 500, thus generating a d-axis voltage command signal for generating the target sound.

[0049] like Figure 4 As shown, in the case of the q-axis, the voltage command generator 330 can input the corresponding value obtained by adding the back EMF compensation value of the q-axis derived from the dq compensator 320 to the output value of the q-axis proportional-integral controller 332 to the RL circuit 333 of the motor 500 to drive the motor 500, thereby generating a q-axis voltage command signal for generating the target sound.

[0050] The dq inverter 340 can convert the voltage command signal generated by the voltage command generator 330 into a three-phase signal. The dq inverter 340 can invert two phases of the d-axis or q-axis voltage command signal generated by the voltage command generator 330 into a three-phase coordinate system signal for application to the motor 500. The conversion of two phases of the d-axis or q-axis signal into a three-phase signal is a known technique, and therefore its detailed description will be omitted.

[0051] The PWM controller 350 can control the PWM signal based on the three-phase voltage command signal converted by the dq inverter 340.

[0052] Specifically, the PWM controller 350 can generate and control the PWM signal (described below) applied to the switching devices included in the inverter 400 based on the three-phase voltage command signal output from the dq inverter 340 to input the desired current to the motor 500. In some embodiments, the PWM controller 350 can be a space vector pulse width modulation (SVPWM) or a sinusoidal pulse width modulation (SPWM). The generation and control of SVPWM or SPWM are known techniques, and therefore their detailed description will be omitted.

[0053] Inverter 400 may include multiple switching devices and can turn the switching devices on / off according to the PWM signal output from PWM controller 350, so that AC power can be supplied to motor 500 to drive motor 500.

[0054] The electric motor 500 may be a permanent magnet synchronous motor (PMSM) and may be an electric motor connected to the steering wheel shaft 700 installed in the vehicle to assist steering. In some embodiments, the electric motor 500 may be an electric motor driven power steering system (MDPS).

[0055] The radiated noise generator 600 can generate target sound using vibrations produced by a motor 500 driven by a motor controller 300. Specifically, see... Figure 5 and Figure 6The radiated noise generator 600 may include: a mounting bracket 610 for fixing the motor 500 and the steering wheel shaft 700; a body 620 including one or more radiated noise generating plates 621 for generating radiated noise using vibrations generated by the motor 500; and one or more stiffness adjusting ribs 630 included in the radiated noise generating plates 621 to adjust the stiffness of the radiated noise generating plates 621 to adjust their natural frequency. The radiated noise generator 600 may also include one or more mass adjusting holes 640 formed in the radiated noise generating plates 621 to adjust the mass of the radiated noise generating plates 621 to adjust their natural frequency. Here, the radiated noise generating plates 621 may be made of plastic or metal.

[0056] Normally, the natural frequency of a structure or similar entity is proportional to its stiffness and inversely proportional to its mass. According to the present invention, the stiffness or mass of the radiated noise generating plate 621 can be adjusted to regulate its natural frequency, thereby generating the desired target sound. The number, size, and position of the stiffness adjustment ribs 630 and mass adjustment holes 640 formed on the radiated noise generating plate 621 are not limited and can be changed according to the selected target sound.

[0057] The thickness of the radiated noise generating plate 621 can be less than the thickness of the mounting bracket 610. Here, the radiated noise generating plate 621 can have a smaller thickness than the mounting bracket 610 to increase the surface radiation efficiency of the radiated noise generator 600. Specifically, in order to amplify the sound in the radiated noise generator 600, the radiated noise generator 600 is preferably designed such that the dynamic impedance of the radiated noise generator 600 is lower than the dynamic impedance of the mounting bracket 610 to which the vibration of the motor 500 is transmitted. Therefore, according to the present invention, the thickness of the radiated noise generating plate 621 can be less than the thickness of the mounting bracket 610, thereby improving the surface radiation efficiency of the radiated noise generator 600, i.e., the radiation efficiency of the radiated noise generating plate 621. In some embodiments, the thickness of the radiated noise generating plate 621 can be equal to or less than half the thickness of the mounting bracket 610.

[0058] Figure 8 The following illustration demonstrates experimental results examining a target sound generated using an active sound-generating device employing an electric motor, according to an embodiment of the present invention. Thus, according to the present invention, an electric motor installed in a vehicle can be controlled without adding a separate actuator or external amplifier, thereby actively generating a desired target sound while the vehicle is in motion, such as... Figure 8 As shown.

[0059] According to the present invention, an electric motor installed in a vehicle can be controlled without adding a separate actuator and external amplifier, thus actively generating the desired target sound while the vehicle is in motion, thereby reducing overall weight and cost.

Claims

1. An active sound-generating device using an electric motor, for actively generating a desired target sound by controlling a three-phase electric motor installed in a vehicle, the device comprising: The target sound generation signal generator is configured to select a target sound and generate a current command signal for driving a motor to generate the target sound. A current sensor is configured to sense the phase current of the motor; The motor controller is configured to generate a voltage command for driving the motor based on a current command signal generated by the target sound generation signal generator, a phase current of the motor sensed by the current sensor, and a back EMF compensation value of the motor, and to control the driving of the motor to generate the target sound. as well as A radiated noise generator is configured to produce a target sound using vibrations generated by a motor driven by the motor controller. The target sound generation signal generator includes at least one of the following: An axis selector is configured to select from the d-axis and q-axis of the motor for controlling the motor to produce a target sound; The target sound selector is configured to select the target sound; The command signal generator is configured to select a sampling frequency based on the frequency of the selected target sound and generate a command signal for generating the target sound. A digital-to-analog converter is configured to convert digital signals generated by the instruction signal generator into analog signals; A low-pass filter is configured to remove low-frequency signals from the signal converted by the digital-to-analog converter; and The noise management unit is configured to detect whether the signal output from the low-pass filter contains noise, and to adjust the sampling frequency and the gain value of the low-pass filter to reduce noise when noise is detected.

2. The apparatus according to claim 1, wherein, The motor controller includes at least one of the following: A dq converter is configured to convert the three-phase current of the motor measured by the current sensor into d-axis and q-axis currents; A dq compensator is configured to compensate for the back electromotive force of the motor along the d-axis and q-axis. A voltage command generator is configured to generate a d-axis or q-axis voltage command to drive the motor, thereby generating the target sound, based on the d-axis and q-axis current command values ​​input from the target sound generation signal generator, the d-axis and q-axis current values ​​converted by the dq converter, and the compensation value through the dq compensator. A dq inverter is configured to convert a voltage command signal generated by the voltage command generator into a three-phase signal; and The pulse width modulation controller is configured to control the pulse width modulation signal based on the three-phase voltage command signal converted by the dq inverter.

3. The apparatus according to claim 2, wherein, The motor controller also includes: A position sensor is configured to sense the position of the rotor of the electric motor; and An angular velocity extraction unit is configured to extract the angular velocity of the motor based on the sensed rotor position. The dq compensator compensates for the back electromotive force of the motor's d-axis and q-axis based on the angular velocity of the motor extracted by the angular velocity extraction unit, the inductance of the d-axis and q-axis, the current command values ​​of the d-axis and q-axis, and the magnetic flux of the motor.

4. The apparatus according to claim 2, wherein, The pulse width modulation controller is either space vector pulse width modulation (SVPWM) or sinusoidal pulse width modulation (SPWM).

5. The apparatus according to claim 2, further comprising: An inverter includes multiple switching devices and is configured to turn the switching devices on / off according to a pulse width modulation signal output from the pulse width modulation controller to provide alternating current to the motor, thereby driving the motor.

6. The apparatus according to claim 1, wherein, The electric motor is a motor-driven power steering system (MDPS) that is connected to the shaft of the steering wheel installed in the vehicle and assists in steering.

7. The apparatus according to claim 6, wherein, The radiated noise generator includes: Mounting brackets are configured to secure the shafts of the motor and the steering wheel; The main body includes one or more radiated noise generating plates configured to generate radiated noise using vibrations generated by the electric motor; and One or more stiffness adjustment ribs are included in the radiated noise generating plate and configured to adjust the stiffness of the radiated noise generating plate to adjust the natural frequency of the radiated noise generating plate.

8. The apparatus according to claim 7, wherein, The radiated noise generator further includes one or more mass adjustment holes formed in the one or more radiated noise generating plates, and the mass of the one or more radiated noise generating plates is adjusted to adjust the natural frequency of the one or more radiated noise generating plates.

9. The apparatus according to claim 7, wherein, The thickness of the one or more radiated noise generating plates is less than the thickness of the mounting bracket.

10. The apparatus according to claim 7, wherein, The one or more radiated noise generating panels are made of plastic or metal materials.

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