A linear resonant motor driving method and system

Abstract

The embodiment of the application provides a linear resonant motor driving method and system, which is based on IV detection to drive a linear resonant motor, can detect driving voltage V and driving current I of the linear resonant motor in real time under the condition that a driving circuit is not stopped, estimates reverse electromotive force and coil impedance of the linear resonant motor in real time by using a self-adaptive sliding mode observer or a self-adaptive Luenberger observer, so that the motor coil resistance value R T and real-time estimation of induced electromotive force BEMF are realized, and the precision of F0 tracking and LRA amplitude control is improved.

Description

Technical Field

[0001] This invention relates to the field of linear resonant motor drive technology, specifically to a linear resonant motor drive method and system. Background Technology

[0002] Linear resonant actuators (LRAs) are commonly used to provide haptic feedback in portable devices. An LRA consists of components such as a spring, coil, and oscillator. It is driven by an LRA driver chip. The driver chip applies an excitation current to the coil, generating a magnetic field that pushes the magnetically driven oscillator in a specific direction. When the direction of the excitation current changes, the magnetic field and the driving force also change. Therefore, if a periodic voltage signal is applied to the coil by the driver chip, the resulting periodic excitation current will drive the oscillator to oscillate back and forth, achieving the haptic feedback effect. Due to the resonant characteristics of the LRA, the amplitude of the oscillation exhibits a bandpass characteristic with the frequency of the driving signal. When the driving signal frequency is at the oscillator's natural frequency (F0), the amplitude of the oscillation reaches its maximum, and the vibration efficiency is optimal.

[0003] Existing LRA drive technologies include F0 calibration technology, windowed F0 tracking technology, F0 tracking based on IV detection, and amplitude closed-loop control technology.

[0004] The F0 calibration technology uses a driver chip to cut off the drive signal in the middle of the drive voltage waveform, allowing the LRA oscillator to oscillate freely for several cycles. The acquisition circuit then collects the induced electromotive force (BEMF) waveform generated during this oscillation. This BEMF waveform is a damped oscillation waveform. By detecting the zero-crossing intervals of the BEMF waveform, the damped oscillation frequency of the LRA is calculated. Based on the difference between the damped oscillation frequency and the standard drive voltage waveform frequency, the sampling frequency of the drive voltage waveform is adjusted to match the natural frequency of the LRA, thereby improving the vibration amplitude and efficiency.

[0005] The open-window F0 tracking technology uses a driver chip to turn off the drive signal within a short time window near the zero-crossing point of the provided drive voltage waveform, detecting the BEMF generated by the movement of the LRA oscillator. When the oscillator velocity switches from positive to negative, the corresponding BEMF also switches from positive to negative. Therefore, after the BEMF detection circuit detects the BEMF zero-crossing point, the LRA drive circuit is reopened, generating a negative drive voltage waveform. The length of this drive voltage waveform is determined by the interval between the current BEMF zero-crossing point and the previous BEMF zero-crossing point. Using this method, the drive voltage and oscillator velocity directions can be aligned, and the zero-crossing points of the drive waveform and BEMF can be time-aligned. Since the drive voltage waveform and oscillator velocity are always in phase, according to the phase frequency characteristics of a linear resonant system, the frequency of the drive signal always tracks the F0 of the oscillator, thus achieving the F0 tracking effect.

[0006] The closed-loop control technology for F0 tracking and LRA amplitude based on IV detection uses the formula E = V₁₀·R, which assumes that the motor coil resistance R is a known quantity. After measuring the coil resistance R during power-on calibration, it is assumed to be a constant value, without considering the increase in coil resistance R due to changes in ambient temperature or prolonged heating of the motor coil by the excitation current. Because the slow change in coil resistance cannot be obtained in real time through measurement, errors occur in the calculation formula E = V₁₀·R, resulting in decreased accuracy of F0 tracking and LRA amplitude detection. Summary of the Invention

[0007] Therefore, embodiments of the present invention provide a linear resonant motor driving method and system to solve the above-mentioned technical problems in the prior art.

[0008] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0009] According to a first aspect of the present invention, this application provides a linear resonant motor driving method, the method comprising:

[0010] Without stopping the drive, the driving voltage V and driving current I of the linear resonant motor are detected in real time.

[0011] Using the driving voltage V and the driving current I, predict the back electromotive force and coil impedance R during motor operation. T ;

[0012] The error signal is obtained by calculating the difference between the input amplitude and the predicted back electromotive force.

[0013] The phase difference between the predicted reverse electromotive force and the current driving voltage waveform is compared to obtain the phase difference comparison result;

[0014] Generate a periodic signal with variable amplitude and frequency, adjust the amplitude of the periodic signal using the error signal, and adjust the frequency of the periodic signal using the phase difference comparison result;

[0015] The periodic signal is used to generate a PWM signal;

[0016] The PWM signal is converted into a voltage signal to drive the linear resonant motor.

[0017] Furthermore, using the driving voltage V and the driving current I, the back electromotive force and coil impedance R during motor operation are predicted. T ,include:

[0018] Based on the set initial estimate of the excitation current The first negative of the initial estimated values ​​of the motor coil resistance voltage drop and the initial estimated values ​​of the back electromotive force is obtained;

[0019] Using the driving voltage V(t1) at the first moment, the first inverse, and the initial estimated value of the voltage drop across the motor coil resistance, the estimated value of the excitation current at the first moment is calculated.

[0020] Using the estimated values ​​of the drive current I(t1) and excitation current at the first moment Calculate the estimated value of the motor coil resistance at the first moment. The second negative of the back electromotive force estimate, and the motor coil resistance estimate at the first moment. The coil impedance R is predicted for the first moment. T ;

[0021] Calculate the estimated value of the motor coil resistance at the first moment. With excitation current estimate The second product yields the estimated value of the motor coil resistance voltage drop at the first moment;

[0022] Based on the second negative value calculated at the previous moment and the estimated value of the voltage drop across the motor coil resistance, combined with the current driving voltage V(t) n This allows us to obtain estimated values ​​of the excitation current at subsequent times.

[0023] Using the driving current I(t) at each subsequent moment n and estimated excitation current Calculate the estimated values ​​of the motor coil resistance at each subsequent time point. The second negative of the back electromotive force estimate, the estimated motor coil resistance at each subsequent time point. The predicted coil impedance R at subsequent time points T ;

[0024] Calculate the estimated values ​​of the motor coil resistance at each subsequent time point. With excitation current estimate The second product is used to obtain the estimated value of the motor coil resistance voltage drop at subsequent time points;

[0025] Calculate the product of the second negative and -1 at each time step; and

[0026] After filtering out the ripple generated by the adaptive observer jitter based on the first product, the estimated value of the back electromotive force at each time moment is obtained and output, wherein the estimated value of the back electromotive force is the predicted back electromotive force.

[0027] Further, adjusting the amplitude of the periodic signal using the error signal includes:

[0028] Compare the magnitude of the error signal with that of 0;

[0029] If the error signal is less than 0, then increase the amplitude of the periodic signal;

[0030] If the error signal is greater than 0, then the amplitude of the periodic signal is reduced.

[0031] Furthermore, the method also includes:

[0032] Determine whether the amplitude of the periodic signal reaches the maximum driving voltage allowed by the linear resonant motor;

[0033] If the amplitude of the periodic signal reaches the maximum driving voltage allowed by the linear resonant motor, then the linear resonant motor is driven using the maximum driving voltage signal.

[0034] Further, adjusting the frequency of the periodic signal using the phase difference comparison result includes:

[0035] If the phase of the predicted back electromotive force lags behind the phase of the current driving voltage waveform, then the frequency of the periodic signal is reduced.

[0036] If the phase of the predicted reverse electromotive force leads the phase of the current driving voltage waveform, then the frequency of the periodic signal is increased.

[0037] Preferably, the method further includes:

[0038] Determine whether the predicted back electromotive force is greater than the preset rated back electromotive force threshold.

[0039] If the predicted back electromotive force is greater than the preset rated back electromotive force threshold, the amplitude protection is triggered and the drive circuit is stopped.

[0040] If the predicted back electromotive force is not greater than the preset rated back electromotive force threshold, the amplitude protection will not be triggered and the drive circuit will not be stopped.

[0041] Preferably, the method further includes:

[0042] Generate the first amplitude input attenuation coefficient;

[0043] Calculate the first product of the first amplitude input attenuation coefficient and the first input amplitude to obtain the adjusted input amplitude;

[0044] The error signal is obtained by calculating the difference between the adjusted input amplitude and the predicted back electromotive force.

[0045] Wherein, the first amplitude input attenuation coefficient is greater than 0 and less than or equal to 1;

[0046] Determine whether the predicted peak value of the reverse electromotive force is higher than the first preset threshold Vth1 of the reverse electromotive force;

[0047] If the predicted peak value of the reverse electromotive force is higher than the first preset threshold Vth1 of the reverse electromotive force, then it is determined whether the first duration for which the predicted peak value of the reverse electromotive force is higher than the first preset threshold Vth1 of the reverse electromotive force reaches the first preset time t1.

[0048] If the first duration reaches the first preset time t1, reduce the first amplitude input attenuation coefficient;

[0049] Determine whether the predicted peak value of the back electromotive force is less than the second back electromotive force preset threshold Vth2;

[0050] If the predicted peak value of the reverse electromotive force is less than the second preset threshold Vth2 of the reverse electromotive force, then determine whether the second duration during which the predicted peak value of the reverse electromotive force is less than the second preset threshold Vth2 of the reverse electromotive force reaches the second preset time t2.

[0051] If the second duration reaches the second preset time t2, the first amplitude input attenuation coefficient is increased.

[0052] Preferably, the method further includes:

[0053] Based on the predicted coil impedance R T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0054]

[0055] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil;

[0056] Determine whether the motor coil temperature T exceeds the preset temperature protection threshold;

[0057] If the motor coil temperature T exceeds the preset temperature protection threshold, the temperature protection is triggered, and the drive circuit is stopped.

[0058] Determine whether the motor coil temperature T is less than the preset temperature protection release threshold;

[0059] If the motor coil temperature T is less than the preset temperature protection release threshold, the drive circuit is restored.

[0060] Preferably, the method further includes:

[0061] Generate the second amplitude input attenuation coefficient;

[0062] Calculate the second product of the second amplitude input attenuation coefficient and the second input amplitude to obtain the adjusted input amplitude;

[0063] The error signal is obtained by calculating the difference between the adjusted input amplitude and the predicted back electromotive force.

[0064] Wherein, the second amplitude input attenuation coefficient is greater than 0 and less than or equal to 1;

[0065] Determine whether the motor coil temperature T is higher than the first preset temperature threshold T1;

[0066] If the motor coil temperature T is higher than the first preset temperature threshold T1, then determine whether the third duration of the motor coil temperature T being higher than the first preset temperature threshold T1 has reached the third preset time t3.

[0067] If the third duration reaches the third preset time t3, reduce the second amplitude input attenuation coefficient;

[0068] Determine whether the motor coil temperature T is less than the second preset temperature threshold T2;

[0069] If the motor coil temperature T is less than the second preset temperature threshold T2, then determine whether the fourth duration of the motor coil temperature T being less than the second preset temperature threshold T2 has reached the fourth preset time t4.

[0070] If the fourth duration reaches the fourth preset time t4, increase the second amplitude input attenuation coefficient.

[0071] According to a second aspect of the present invention, this application provides a linear resonant motor drive system, the system comprising:

[0072] The circuit consists of an analog circuit section and a digital circuit section. The analog circuit section includes a current detection ADC, a voltage detection ADC, and a driving circuit. The digital circuit section includes an adaptive observer with parameter identification, a driving voltage controller, an F0 detection module, a driving waveform DDS, and a PWM modulator.

[0073] The current detection ADC is used to detect the drive current I of the linear resonant motor in real time without stopping the drive.

[0074] The voltage detection ADC is used to detect the driving voltage V of the linear resonant motor in real time without stopping the drive.

[0075] The adaptive observer is used to predict the back electromotive force and coil impedance R during motor operation using the driving voltage V and the driving current I. T ;

[0076] The drive voltage controller is used to calculate the difference between the input amplitude and the predicted back electromotive force to obtain an error signal;

[0077] The F0 detection module is used to compare the phase difference between the predicted back electromotive force and the current driving voltage waveform to obtain the phase difference comparison result.

[0078] The driving waveform DDS is used to generate a periodic signal with variable amplitude and frequency. The amplitude of the periodic signal is adjusted using the error signal, and the frequency of the periodic signal is adjusted using the phase difference comparison result.

[0079] The PWM modulator is used to generate a PWM signal using the periodic signal;

[0080] The driving circuit is used to convert the PWM signal into a voltage signal to drive the linear resonant motor.

[0081] Preferably, the digital circuit section further includes: an amplitude protection module, a temperature calculation module, and a temperature protection module;

[0082] The amplitude protection module is used to determine whether the predicted reverse electromotive force is greater than the preset rated reverse electromotive force threshold. If the predicted reverse electromotive force is greater than the preset rated reverse electromotive force threshold, the amplitude protection is triggered and the driving circuit is stopped. If the predicted reverse electromotive force is not greater than the preset rated reverse electromotive force threshold, the amplitude protection is not triggered and the driving circuit is not stopped.

[0083] The temperature calculation module is used to calculate the coil impedance R based on the predicted temperature. T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0084]

[0085] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil;

[0086] The temperature protection module is used to determine whether the motor coil temperature T exceeds a preset temperature protection threshold; if the motor coil temperature T exceeds the preset temperature protection threshold, temperature protection is triggered and the drive circuit is stopped; it also determines whether the motor coil temperature T is less than a preset temperature protection release threshold; if the motor coil temperature T is less than the preset temperature protection release threshold, the drive circuit is restored.

[0087] Preferably, the digital circuit section further includes: an amplitude control module;

[0088] The amplitude control module is used to generate a first amplitude input attenuation coefficient; calculate the first product of the first amplitude input attenuation coefficient and the input amplitude to obtain the adjusted input amplitude; and calculate the difference between the adjusted input amplitude and the predicted back electromotive force by the drive voltage controller to obtain the error signal.

[0089] Preferably, the digital circuit section further includes a temperature control module;

[0090] The temperature control module is used to generate a second amplitude input attenuation coefficient; calculate the second product of the second amplitude input attenuation coefficient and the input amplitude to obtain the adjusted input amplitude; and the driving voltage controller calculates the difference between the adjusted input amplitude and the predicted back electromotive force to obtain the error signal.

[0091] Compared with the prior art, the linear resonant motor driving method and system provided in this application, based on IV detection to drive the linear resonant motor, can detect the driving voltage V and driving current I of the linear resonant motor in real time without stopping the driving circuit. Using an adaptive sliding mode observer or an adaptive Luenberger observer, the back electromotive force and coil impedance of the linear resonant motor can be estimated in real time, thereby achieving real-time estimation of the motor coil resistance value R. T Real-time estimation of induced electromotive force (BEMF) improves the accuracy of F0 tracking and LRA amplitude control. Attached Figure Description

[0092] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0093] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0094] Figure 1 This is a schematic diagram of the structure of a linear resonant motor drive system provided in the first embodiment of the present invention;

[0095] Figure 2 This is a schematic diagram of a linear resonant motor drive system provided in the second embodiment of the present invention;

[0096] Figure 3 A schematic diagram of a linear resonant motor drive system provided in the third embodiment of the present invention;

[0097] Figure 4 A flowchart illustrating a linear resonant motor driving method provided in an embodiment of the present invention;

[0098] Figure 5 The back electromotive force and coil impedance R during the operation of the motor are predicted according to embodiments of the present invention. T A flowchart;

[0099] Figure 6 This is a schematic diagram of the structure of an adaptive observer provided in an embodiment of the present invention. Detailed Implementation

[0100] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0101] Existing F0 calibration techniques are only suitable for production line calibration and startup calibration. If the environment or temperature changes after the portable device is powered on, the drive voltage waveform cannot update its frequency to track the oscillator's natural frequency changes in real time. Furthermore, due to the nonlinear characteristics introduced by the mechanical structure of the linear resonant motor, its natural frequency will also shift when the amplitude or load changes. Existing F0 calibration techniques cannot solve the problem of the oscillator's natural frequency shifting with changes in oscillator amplitude.

[0102] Existing windowed F0 tracking technology achieves synchronization between the drive waveform and the oscillator's vibration direction by stopping the drive waveform and detecting the BEMF zero-crossing point. During the zero-crossing point, the chip stops the drive circuit, resulting in additional harmonic components and causing problems such as high audio noise.

[0103] The existing windowed F0 tracking technology causes the average driving signal amplitude to decrease as the zero-crossing window time increases because the chip stops driving the circuit transistors during the zero-crossing period. An additional compensation algorithm is needed to adjust the output amplitude to achieve the required consistency of vibration amplitude.

[0104] In existing windowed F0 tracking technology, during the zero-crossing period, the average drive signal amplitude decreases as the zero-crossing window time increases because the chip stops driving the circuit, resulting in a reduction in the maximum average drive signal amplitude under the rated power supply voltage.

[0105] Existing open-window F0 tracking technology encounters a problem during zero-crossing: the chip stops driving the circuit, but the current in the parasitic inductance of the motor coil cannot change abruptly, resulting in inductor freewheeling. This causes the parasitic diode of the chip's output power transistor to conduct, affecting BEMF detection at the output. Therefore, an additional wait for the parasitic inductance to discharge is required before BEMF detection, increasing the zero-crossing wait time. To avoid reliability issues caused by the parasitic diode of the chip's output power transistor conducting and substrate debiasing, additional discharge circuits or increased device spacing are needed, thereby increasing chip cost.

[0106] The closed-loop control technology for F0 tracking and LRA amplitude based on IV detection uses the formula E=VI·R, which assumes that the motor coil resistance R is a known quantity. After measuring the coil resistance R during power-on calibration, R is considered a constant value, without considering the increase in coil resistance R due to changes in ambient temperature or prolonged heating of the motor coil by the excitation current. Because the slow change in coil resistance cannot be obtained in real time through measurement, errors occur in the calculation formula E=VI·R, resulting in decreased accuracy of F0 tracking and LRA amplitude detection.

[0107] Furthermore, none of the above technologies can currently measure the temperature of the motor coil, and therefore cannot achieve over-temperature protection for the LRA under prolonged, high-power conditions.

[0108] refer to Figure 1 The first embodiment of this application provides a linear resonant motor drive system, which includes: an analog circuit section 1 and a digital circuit section 2. The analog circuit section 1 includes: a current detection ADC (Analog to Digital Converter) 11, a voltage detection ADC (Analog to Digital Converter) 12, and a drive circuit 13. The digital circuit section 2 includes: an adaptive observer 21 with parameter identification, a drive voltage controller 22, an F0 detection module 23, a drive waveform DDS (Direct Digital Synthesizer) 24, and a PWM (Pulse Width Modulation) modulator 25.

[0109] Specifically, the current detection ADC 11 is used to detect the drive current I of the linear resonant motor 3 in real time without stopping the drive; the voltage detection ADC 12 is used to detect the drive voltage V of the linear resonant motor 3 in real time without stopping the drive; and the adaptive observer 21 is used to predict the back electromotive force and coil impedance R during motor operation using the drive voltage V and the drive current I. T The drive voltage controller 22 is used to calculate the difference between the input amplitude and the predicted back electromotive force to obtain an error signal; the F0 detection module 23 is used to compare the phase difference between the predicted back electromotive force and the current drive voltage waveform to obtain a phase difference comparison result; the drive waveform DDS 24 is used to generate a periodic signal with variable amplitude and frequency, adjust the amplitude of the periodic signal using the error signal, and adjust the frequency of the periodic signal using the phase difference comparison result; the PWM modulator 25 is used to generate a PWM signal using the periodic signal; and the drive circuit 13 is used to convert the PWM signal into a voltage signal to drive the linear resonant motor 3.

[0110] Furthermore, the digital circuit section 2 also includes an amplitude protection module 26, which is used to determine whether the predicted reverse electromotive force is greater than a preset rated reverse electromotive force threshold. If the predicted reverse electromotive force is greater than the preset rated reverse electromotive force threshold, amplitude protection is triggered and the drive circuit 3 is stopped. If the predicted reverse electromotive force is not greater than the preset rated reverse electromotive force threshold, amplitude protection is not triggered and the drive circuit 3 is not stopped.

[0111] During the operation of a linear resonant motor (LRA), its coils generate heat due to the applied excitation current. If the coils generate heat for an extended period and cannot dissipate it in time, it can lead to high temperatures inside the LRA, resulting in decreased amplitude control accuracy of the oscillator, noise, and even permanent damage.

[0112] Furthermore, the digital circuit section 2 also includes: a temperature calculation module 27 and a temperature protection module 28; the temperature calculation module 27 is used to calculate the temperature based on the predicted coil impedance R. T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0113]

[0114] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil. The temperature protection module 28 is used to determine whether the motor coil temperature T exceeds the preset temperature protection threshold; if the motor coil temperature T exceeds the preset temperature protection threshold, the temperature protection is triggered and the drive circuit 3 is stopped; it also determines whether the motor coil temperature T is less than the preset temperature protection release threshold; if the motor coil temperature T is less than the preset temperature protection release threshold, the drive circuit 3 is restored.

[0115] This invention discloses a linear resonant motor drive system that includes both amplitude protection and temperature protection functions. In this embodiment, when the motor coil temperature T exceeds a preset temperature protection threshold, the motor coil temperature protection function is triggered, shutting down the drive circuit, thereby preventing the motor from malfunctioning or being permanently damaged due to overheating.

[0116] refer to Figure 2 The second embodiment of this application provides a linear resonant motor drive system, which similarly includes: an analog circuit section 1 and a digital circuit section 2. The analog circuit section 1 includes: a current detection ADC 11, a voltage detection ADC 12, and a drive circuit 13; the digital circuit section 2 includes: an adaptive observer 21 with parameter identification, a drive voltage controller 22, an F0 detection module 23, a drive waveform DDS 24, and a PWM modulator 25.

[0117] Specifically, the current detection ADC 11 is used to detect the drive current I of the linear resonant motor 3 in real time without stopping the drive; the voltage detection ADC 12 is used to detect the drive voltage V of the linear resonant motor 3 in real time without stopping the drive; and the adaptive observer 21 is used to predict the back electromotive force and coil impedance R during motor operation using the drive voltage V and the drive current I. TThe drive voltage controller 22 is used to calculate the difference between the input amplitude and the predicted back electromotive force to obtain an error signal; the F0 detection module 23 is used to compare the phase difference between the predicted back electromotive force and the current drive voltage waveform to obtain a phase difference comparison result; the drive waveform DDS 24 is used to generate a periodic signal with variable amplitude and frequency, adjust the amplitude of the periodic signal using the error signal, and adjust the frequency of the periodic signal using the phase difference comparison result; the PWM modulator 25 is used to generate a PWM signal using the periodic signal; and the drive circuit 13 is used to convert the PWM signal into a voltage signal to drive the linear resonant motor 3.

[0118] Furthermore, the digital circuit section 2 also includes: an amplitude control module 29; the amplitude control module 29 is used to generate a first amplitude input attenuation coefficient; calculate the first product of the first amplitude input attenuation coefficient and the input amplitude to obtain the adjusted input amplitude; and the driving voltage controller 22 calculates the difference between the adjusted input amplitude and the predicted back electromotive force to obtain an error signal.

[0119] During the operation of a linear resonant motor (LRA), its coils generate heat due to the applied excitation current. If the coils generate heat for an extended period and cannot dissipate it in time, it can lead to high temperatures inside the LRA, resulting in decreased amplitude control accuracy of the oscillator, noise, and even permanent damage.

[0120] Furthermore, the digital circuit section 2 also includes: a temperature calculation module 27 and a temperature protection module 28; the temperature calculation module 27 is used to calculate the temperature based on the predicted coil impedance R. T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0121]

[0122] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil. The temperature protection module 28 is used to determine whether the motor coil temperature T exceeds the preset temperature protection threshold; if the motor coil temperature T exceeds the preset temperature protection threshold, the temperature protection is triggered and the drive circuit 3 is stopped; it also determines whether the motor coil temperature T is less than the preset temperature protection release threshold; if the motor coil temperature T is less than the preset temperature protection release threshold, the drive circuit 3 is restored.

[0123] This invention discloses a linear resonant motor drive system that includes both amplitude control and temperature protection functions. In this embodiment, when the motor coil temperature T exceeds a preset temperature protection threshold, the motor coil temperature protection function is triggered, shutting down the drive circuit and preventing the motor from malfunctioning or suffering permanent damage due to overheating.

[0124] refer to Figure 3 The third embodiment of this application provides a linear resonant motor drive system, which includes: an analog circuit section 1 and a digital circuit section 2. The analog circuit section 1 includes: a current detection ADC 11, a voltage detection ADC 12, and a drive circuit 13. The digital circuit section 2 includes: an adaptive observer 21 with parameter identification, a drive voltage controller 22, an F0 detection module 23, a drive waveform DDS 24, and a PWM modulator 25.

[0125] Specifically, the current detection ADC 11 is used to detect the drive current I of the linear resonant motor 3 in real time without stopping the drive; the voltage detection ADC 12 is used to detect the drive voltage V of the linear resonant motor 3 in real time without stopping the drive; and the adaptive observer 21 is used to predict the back electromotive force and coil impedance R during motor operation using the drive voltage V and the drive current I. T The drive voltage controller 22 is used to calculate the difference between the input amplitude and the predicted back electromotive force to obtain an error signal; the F0 detection module 23 is used to compare the phase difference between the predicted back electromotive force and the current drive voltage waveform to obtain a phase difference comparison result; the drive waveform DDS 24 is used to generate a periodic signal with variable amplitude and frequency, adjust the amplitude of the periodic signal using the error signal, and adjust the frequency of the periodic signal using the phase difference comparison result; the PWM modulator 25 is used to generate a PWM signal using the periodic signal; and the drive circuit 13 is used to convert the PWM signal into a voltage signal to drive the linear resonant motor 3.

[0126] Furthermore, the digital circuit section 2 also includes an amplitude protection module 26, which is used to determine whether the predicted reverse electromotive force is greater than a preset rated reverse electromotive force threshold. If the predicted reverse electromotive force is greater than the preset rated reverse electromotive force threshold, amplitude protection is triggered and the drive circuit 3 is stopped. If the predicted reverse electromotive force is not greater than the preset rated reverse electromotive force threshold, amplitude protection is not triggered and the drive circuit 3 is not stopped.

[0127] During the operation of a linear resonant motor (LRA), its coils generate heat due to the applied excitation current. If the coils generate heat for an extended period and cannot dissipate it in time, it can lead to high temperatures inside the LRA, resulting in decreased amplitude control accuracy of the oscillator, noise, and even permanent damage.

[0128] Furthermore, the digital circuit section 2 also includes: a temperature calculation module 27 and a temperature control module 210; the temperature calculation module 27 is used to calculate the temperature based on the predicted coil impedance R. T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0129]

[0130] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil. The temperature control module 210 is used to generate the second amplitude input attenuation coefficient; calculate the second product of the second amplitude input attenuation coefficient and the input amplitude to obtain the adjusted input amplitude; the drive voltage controller 22 calculates the difference between the adjusted input amplitude and the predicted back electromotive force to obtain the error signal.

[0131] As can be seen, the linear resonant motor drive system disclosed in this embodiment of the invention includes both amplitude protection and temperature control functions.

[0132] Further, refer to Figure 6 In this embodiment of the application, as described above, when the linear resonant motor drive circuit 1 is driven without interruption, the voltage detection ADC 11 detects the voltage waveform across the linear resonant motor 3, and the current detection ADC 12 detects the current waveform flowing through the linear resonant motor 3.

[0133] refer to Figure 6 The relationship between the driving voltage and driving current of the linear resonant motor 3 can be described by the IV characteristic model of the linear resonant motor. The input signal of the IV characteristic model of the linear resonant motor is the driving voltage V of the linear resonant motor. The output signal of the IV characteristic model of the linear resonant motor is the driving current I of the linear resonant motor. The transfer function of the IV characteristic model of the linear resonant motor is the admittance (I / V) of the linear resonant motor. Due to the resonant characteristics of the linear resonant motor, the vibration amplitude and vibration velocity of the linear resonant motor reach their maximum values ​​at its natural frequency. The back electromotive force of the linear resonant motor is proportional to the vibration velocity of the linear resonant motor, and therefore the back electromotive force also reaches its maximum value at its natural frequency. According to the formula BEMF = VI·R, under the condition that the amplitude of the input driving voltage V is constant, the output (driving current I) of the IV characteristic model of the linear resonant motor reaches its minimum value at the natural frequency. Therefore, the IV characteristic model of the linear resonant motor exhibits band-stop characteristics similar to a notch filter.

[0134] Further, refer to Figure 6 The adaptive observer 21 includes: a hybrid arithmetic unit 210, a first amplifier 211, an integrator 212, a two-input subtractor 213, a parameter identification module 214, a multiplier 215, an observation unit 216, a second amplifier 217, a third amplifier 218, and a low-pass filter 219.

[0135] In this embodiment of the invention, the preset parameters of the adaptive observer 21 include: the coil inductance L of the linear resonant motor, which is a known quantity provided by the LRA manufacturer or can be measured by an impedance meter, with a typical value of 100uH; and the adaptive sliding mode adaptive observer gain K or the adaptive Lumberjack adaptive observer gain L. d , is a preset positive real number. The iteration coefficient α of the parameter identification module is a preset positive real number. The low-pass filter's bandwidth, order, and other parameters are defined, with a typical bandwidth of 500Hz and a typical order of 4th.

[0136] Specifically, the multiplier 215 calculates the initial estimate of the excitation current. Compared with the preset initial estimate of the motor coil resistance The second product yields the initial estimate of the voltage drop across the motor coil resistance; the initial drive current I(t0) and the initial estimate of the excitation current are calculated by the two-input subtractor 213. The difference is used to obtain the initial error of the excitation current estimation. The observation unit 216 utilizes either the adaptive sliding mode observer gain K or the adaptive Lumberjack observer gain L. d Initial error in estimating excitation current The process is as follows: the product of the processed excitation current estimation initial error and the second gain L is calculated by the second amplifier 217 to obtain the first negative value of the initial estimate of the back electromotive force; the hybrid arithmetic unit 210 takes the driving voltage V(t1) at the first moment and the first negative value as positive inputs, and the initial estimate of the motor coil resistance voltage drop as negative inputs, and performs mixed addition and subtraction operations to obtain the estimated value of the excitation voltage of the motor coil at the first moment; the product of the estimated value of the excitation voltage at the first moment and the first gain 1 / L is calculated by the first amplifier 211 to obtain the estimated value of the excitation current change rate at the first moment. The integrator 212 uses the estimated value of the excitation current change rate at the first moment. By performing integration, the estimated value of the excitation current at the first moment is obtained. The two-input subtractor 213 calculates the estimated values ​​of the drive current I(t1) and the excitation current at the first moment. The difference is used to obtain the excitation current estimation error at the first moment. The parameter identification module 214 uses the estimated excitation current value at the first moment. And excitation current estimation error Iterative calculations are performed to detect changes in the motor coil resistance with external factors, and the estimated value of the motor coil resistance at the first moment is obtained and output. The estimated value of the motor coil resistance at the first moment is calculated using multiplier 215. With excitation current estimate The second product yields the estimated voltage drop across the motor coil resistance at the first moment; this is then calculated by observation unit 216 using either the adaptive sliding mode observer gain K or the adaptive Luenberger observer gain L. d The error in estimating the excitation current at the first moment Processing is performed; the excitation current estimation error at the first moment after processing is calculated by the second amplifier 217. The product of the first gain L and the second negative value of the back electromotive force estimate at the first moment is obtained; the hybrid arithmetic unit 210 is also used to convert the current driving voltage V(t) into the second negative value of the back electromotive force estimate at the first moment. n The first amplifier 211 takes the second negative number from the previous moment as a positive input and the estimated voltage drop across the motor coil resistance from the previous moment as a negative input, performing a mixed addition and subtraction operation to obtain the estimated excitation voltage of the motor coil at subsequent moments. The first amplifier 211 is also used to calculate the product of the estimated excitation voltage at subsequent moments and the first gain 1 / L to obtain the estimated rate of change of the excitation current at subsequent moments. Integrator 212 is also used to estimate the rate of change of excitation current at subsequent time points. By performing integration, the estimated values ​​of the excitation current at subsequent time points are obtained. The two-input subtractor 213 is also used to calculate the drive current I(t) at subsequent time steps. n ) and the estimated value of excitation current The difference is used to obtain the excitation current estimation error at subsequent times. The parameter identification module 214 is also used to utilize the estimated excitation current values ​​at subsequent times. And excitation current estimation error Iterative calculations are performed to detect changes in the motor coil resistance with external factors, and the estimated values ​​of the motor coil resistance at subsequent time points are obtained and output. Multiplier 215 is also used to calculate the estimated values ​​of the motor coil resistance at subsequent time points. With excitation current estimate The second product is used to obtain the estimated value of the motor coil resistance voltage drop at subsequent time points; the observation unit 216 is also used to utilize the adaptive sliding mode observer gain K or the adaptive Luenberger observer gain L d The estimation error of the excitation current at subsequent times The second amplifier 217 is also used to calculate the excitation current estimation error at subsequent time points after processing. The product of the second gain L and the second inverse is used to obtain the second inverse of the back electromotive force estimate at each subsequent time step. The third amplifier 218 calculates the first product of the second inverse and -1. After filtering out the ripple generated by the adaptive observer jitter based on the first product by the low-pass filter 219, the back electromotive force estimate is obtained and output.

[0137] Compared with the prior art, the linear resonant motor drive system provided in this application embodiment, based on IV detection to drive the linear resonant motor, can detect the driving voltage V and driving current I of the linear resonant motor in real time without stopping the drive circuit. Using an adaptive sliding mode observer or an adaptive Luenberger observer, the back electromotive force and coil impedance of the linear resonant motor can be estimated in real time, thereby achieving real-time estimation of the motor coil resistance value R. T Real-time estimation of the induced electromotive force (BEMF) improves the accuracy of F0 tracking and LRA amplitude control. Even if factors such as interface plugging / unplugging, ambient temperature changes, and motor long-term vibration temperature rise cause changes in R, these can be detected in real time to ensure the correct BEMF detection value.

[0138] Corresponding to the linear resonant motor drive system disclosed above, this invention also discloses a linear resonant motor drive method. The following details a linear resonant motor drive method disclosed in this invention, in conjunction with the linear resonant motor drive system described above.

[0139] like Figure 4 As shown in the figure, this application provides a linear resonant motor driving method, which specifically includes the following steps.

[0140] Without stopping the drive, the drive current I of the linear resonant motor 3 is detected in real time by the current detection ADC 11; the drive voltage V of the linear resonant motor 3 is detected in real time by the voltage detection ADC 12.

[0141] The IV characteristics of the linear resonant motor 3 are detected in real time by the current detection ADC 11 and the voltage detection ADC 12. Specifically, the IV characteristics of the linear resonant motor 3 include the driving voltage V and the driving current I. Under the condition of not stopping the drive, the voltage detection ADC 11 detects the driving voltage V of the linear resonant motor 3 in real time and sends it to the adaptive observer 21, and the current detection ADC 12 detects the driving current I of the linear resonant motor 3 in real time and sends it to the adaptive observer 21.

[0142] The adaptive observer 21 is used to predict the back electromotive force and coil impedance R during motor operation using the drive voltage V and drive current I. T ,refer to Figure 5 and Figure 6 The implementation steps described above are described in detail below.

[0143] The adaptive observer 21 receives the currently detected driving voltage V(t) of the linear resonant motor 3. n ) and driving current I(t)n First, set the initial estimate of the excitation current. If the value is 0, the first negative number of the initial estimated value of the motor coil resistance voltage drop and the initial estimated value of the back electromotive force is obtained.

[0144] Specifically, obtaining the initial estimate of the motor coil resistance voltage drop includes: setting the initial estimate of the excitation current. The value is 0; the initial estimate of the excitation current is calculated by multiplier 215. Compared with the preset initial estimate of the motor coil resistance The second product yields the initial estimate of the voltage drop across the motor coil resistance.

[0145] Specifically, the first negative value of the aforementioned back electromotive force estimate includes: the initial drive current I(t0) calculated by the two-input subtractor 213 and the initial estimate of the excitation current. The difference is used to obtain the initial error of the excitation current estimation. The observation unit 216 utilizes either the adaptive sliding mode observer gain K or the adaptive Lumberjack observer gain L. d Initial error in estimating excitation current The process is performed; the product of the initial error of the processed excitation current estimate and the second gain L is calculated by the second amplifier 217 to obtain the first negative number of the initial estimate of the reverse electromotive force.

[0146] In this embodiment, the adaptive observer 21 is divided into two types: an adaptive sliding mode adaptive observer and an adaptive Lumberjack adaptive observer. When the adaptive observer 21 is an adaptive sliding mode adaptive observer, the observation unit 216 estimates the initial error of the excitation current. After performing the sgn() operation, multiply by K to obtain the output. The specific calculation formula for observation unit 216 is as follows: Where sgn is the sign function and K is the gain of the adaptive sliding mode adaptive observer. A larger K results in a faster tracking rate and a more stable system, but also more severe chattering. When the adaptive observer 21 is an adaptive Lumberjack adaptive observer, the observation unit 216 directly estimates the initial error using the excitation current. Multiply by L d As the output, the specific calculation formula for observation unit 216 is: Among them, L d For the Luneburg adaptive observer gain, L d The larger the value, the faster the tracking rate of the adaptive Romberg adaptive observer, but the worse its stability.

[0147] The adaptive observer 21 uses the driving voltage V(t1), the first inverse, and the initial estimated value of the voltage drop across the motor coil resistance at the first moment to calculate the estimated value of the excitation current at the first moment. Specifically, in this embodiment of the invention, the hybrid arithmetic unit 210 is a three-input addition and subtraction hybrid arithmetic unit, obtained by circuit analysis of the LRA coil loop using Kirchhoff's voltage law. The above calculation of the estimated excitation current value at the first moment... The specific steps include: the voltage detection ADC 11 detects the driving voltage V(t1) of the linear resonant motor 3 in real time at the first moment and sends it to the hybrid arithmetic unit 210; the first negative value of the initial estimate of the back electromotive force calculated by the second amplifier 217 is sent to the hybrid arithmetic unit 210; the initial estimate of the motor coil resistance voltage drop calculated by the multiplier 215 is sent to the hybrid arithmetic unit 210; the hybrid arithmetic unit 210 takes the driving voltage V(t1) and the first negative value at the first moment as positive inputs and the initial estimate of the motor coil resistance voltage drop as negative inputs, performs addition and subtraction operations to obtain the estimated value of the excitation voltage of the motor coil at the first moment and sends it to the first amplifier 211; the first amplifier 211 calculates the product of the estimated value of the excitation voltage at the first moment and the first gain 1 / L to obtain the estimated value of the excitation current change rate at the first moment. And send it to integrator 212; integrator 212 uses the excitation current change rate estimate at the first moment to estimate the value. By performing integration, the estimated value of the excitation current at the first moment is obtained.

[0148] The integrator 212 uses the excitation current change rate estimate at the first moment to estimate the value. The formula for integration is as follows:

[0149]

[0150] Among them, t n It is the current moment. This is the estimated rate of change of the excitation current at time τ, where d is the differential sign and τ is the integral variable. This is the initial estimated value of the excitation current, which is 0.

[0151] Due to the low-pass characteristic of integrator 212, integrator 212 can... The ripples on the signal generated by the jitter of the adaptive sliding mode observer or the adaptive Luneburg observer are smoothed and filtered.

[0152] The adaptive observer 21 uses the estimated values ​​of the driving current I(t1) and the excitation current at the first moment. Calculate the estimated value of the motor coil resistance at the first moment. The second negative of the back electromotive force estimate, and the motor coil resistance estimate at the first moment. The coil impedance R is predicted for the first moment. T ; Calculate the estimated value of the motor coil resistance at the first moment. With excitation current estimate The second product yields the estimated value of the motor coil resistance voltage drop at the first moment.

[0153] In this embodiment of the invention, the above calculation of the estimated value of the motor coil resistance at the first moment is... The specific steps include: calculating the estimated values ​​of the driving current I(t1) and the excitation current at the first moment using the two-input subtractor 213. The difference is used to obtain the excitation current estimation error at the first moment. And the excitation current estimation error at the first moment The signal is sent to the parameter identification module 214; the parameter identification module 214 then uses the estimated excitation current value from the first moment. And excitation current estimation error Iterative calculations are performed to detect changes in the motor coil resistance with external factors, and the estimated value of the motor coil resistance at the first moment is obtained and output. Then, the estimated value of the motor coil resistance at the first moment is calculated using multiplier 215. With excitation current estimate The second product yields the estimated value of the motor coil resistance voltage drop at the first moment.

[0154] Furthermore, the estimated values ​​of the motor coil resistance at each first moment... The iterative calculation formula is as follows:

[0155]

[0156] Where L is the coil inductance of the linear resonant motor; α is the iteration coefficient, which is a preset positive real number; This is a preset initial value, usually set to the nominal coil resistance value provided by the linear resonant motor manufacturer.

[0157] In addition, the specific steps for calculating the second negative of the estimated back electromotive force at the first moment include: calculating the estimated values ​​of the driving current I(t1) and the excitation current at the first moment using the two-input subtractor 213. The difference is used to obtain the excitation current estimation error at the first moment. And the excitation current estimation error at the first moment The signal is sent to observation unit 216; observation unit 216 then uses either the adaptive sliding mode observer gain K or the adaptive Lumberjack observer gain L. d The error in estimating the excitation current at the first moment Processing is performed; the excitation current estimation error at the first moment after processing is calculated by the second amplifier 217. The product of this and the second gain L yields the second negative of the estimated reverse electromotive force at the first moment.

[0158] Similarly, in this embodiment, the adaptive observer 21 is divided into two types: adaptive sliding mode adaptive observer and adaptive Romberg adaptive observer. When the adaptive observer 21 is an adaptive sliding mode adaptive observer, the observation unit 216 estimates the excitation current error. After performing the sgn() operation, multiply by K to obtain the output. The specific calculation formula for observation unit 216 is as follows: Where sgn is the sign function and K is the gain of the adaptive sliding mode adaptive observer. A larger K results in a faster tracking rate and a more stable system, but also more severe chattering. When the adaptive observer 21 is an adaptive Lumberjack adaptive observer, the observation unit 216 directly uses the excitation current to estimate the error. Multiply by L d As the output, the specific calculation formula for observation unit 216 is: Among them, L d For the Luneburg adaptive observer gain, L d The larger the value, the faster the tracking rate of the adaptive Romberg adaptive observer, but the worse its stability.

[0159] The adaptive observer 21 calculates the second inverse number based on the previous moment and the estimated value of the motor coil resistance voltage drop, combined with the current driving voltage V(t) n This allows us to obtain estimated values ​​of the excitation current at subsequent times. At this point, n>1.

[0160] In this embodiment of the invention, the above-mentioned estimated values ​​of excitation current at subsequent times are obtained. The specific steps include: the voltage detection ADC 11 continuously detecting the driving voltage V(t) of the linear resonant motor 3 at each subsequent moment. n The second inverse calculated by the second amplifier 217 at the previous moment is sent to the hybrid arithmetic unit 210. The estimated value of the motor coil resistance voltage drop calculated by the multiplier 215 at the previous moment is also sent to the hybrid arithmetic unit 210. The hybrid arithmetic unit 210 then sends the current driving voltage V(t) to the hybrid arithmetic unit 210. nThe second negative number from the previous moment is used as the positive input, and the estimated value of the motor coil resistance voltage drop from the previous moment is used as the negative input. A mixed addition and subtraction operation is performed to obtain the estimated excitation voltage of the motor coil at subsequent moments. This estimated excitation voltage is then sent to the first amplifier 211. The first amplifier 211 calculates the product of the estimated excitation voltage at each subsequent moment and the first gain 1 / L to obtain the estimated rate of change of the excitation current at each subsequent moment. And send it to integrator 212; integrator 212 uses the excitation current change rate estimate at subsequent time points to estimate the value. By performing integration, the estimated values ​​of the excitation current at subsequent time points are obtained.

[0161] Furthermore, the estimated excitation current change rate at subsequent time points is used. The formula for integration is as follows:

[0162]

[0163] Among them, t n It is the current moment. This is the estimated rate of change of the excitation current at time τ, where d is the differential sign and τ is the integral variable. It is the initial estimate of the excitation current. The initial estimate of the excitation current is 0, and n>1.

[0164] The adaptive observer 21 utilizes the driving current I(t) at subsequent time points. n and estimated excitation current Calculate the estimated values ​​of the motor coil resistance at each subsequent time point. The second negative of the back electromotive force estimate, the estimated motor coil resistance at each subsequent time point. The predicted coil impedance R at subsequent time points T ; Calculate the estimated values ​​of the motor coil resistance at each subsequent time point. With excitation current estimate The second product yields the estimated voltage drop across the motor coil resistance at subsequent time points.

[0165] In this embodiment of the invention, the above calculation of the estimated values ​​of the motor coil resistance at each subsequent time point... The second inverse of the estimated voltage drop across the motor coil resistance and the estimated back electromotive force are obtained through the following steps: The two-input subtractor 213 calculates the drive current I(t) at subsequent time points. n ) and the estimated value of excitation current The difference is used to obtain the excitation current estimation error at subsequent times. And send it to parameter identification module 214; the parameter identification module 214 uses the estimated excitation current values ​​at subsequent times. And excitation current estimation error Iterative calculations are performed to detect changes in the motor coil resistance with external factors, and the estimated values ​​of the motor coil resistance at subsequent time points are obtained and output. The multiplier 215 calculates the estimated values ​​of the motor coil resistance at subsequent time points. With excitation current estimate The second product yields the estimated voltage drop across the motor coil resistance at subsequent time points; this is then calculated by observation unit 216 using either the adaptive sliding mode observer gain K or the adaptive Luenberger observer gain L. d The estimation error of the excitation current at subsequent times The data is processed; the second amplifier 217 calculates the estimated error of the excitation current at subsequent time points after processing. The product of this and the second gain L yields the second negative of the estimated back electromotive force at subsequent time points.

[0166] Furthermore, the estimated values ​​of the motor coil resistance at subsequent time points... The iterative calculation formula is as follows:

[0167]

[0168] Where L is the coil inductance of the linear resonant motor; α is the iteration coefficient, which is a preset positive real number; This is a preset initial value, usually set to the nominal coil resistance value provided by the linear resonant motor manufacturer.

[0169] The second inverse of the back electromotive force estimate at each subsequent time point, calculated by the second amplifier 217, is sent to the third amplifier 218. The third amplifier 218 calculates the first product of the second inverse of the back electromotive force estimate at each subsequent time point and -1, and sends it to the low-pass filter 219. The low-pass filter 219 filters out the ripple generated by the adaptive observer jitter based on the first product, and then obtains and outputs the back electromotive force estimate at each time point.

[0170] The error signal is obtained by calculating the difference between the input amplitude and the predicted reverse electromotive force through the drive voltage controller 22.

[0171] The phase difference comparison result is obtained by comparing the predicted reverse electromotive force with the current driving voltage waveform through the F0 detection module 23.

[0172] A periodic signal with variable amplitude and frequency is generated by driving waveform DDS24. The amplitude of the periodic signal is adjusted by using error signal, and the frequency of the periodic signal is adjusted by using phase difference comparison result.

[0173] Furthermore, adjusting the amplitude of the periodic signal using the error signal specifically includes: comparing the error signal with the value of 0; if the error signal is less than 0, increasing the amplitude of the periodic signal; if the error signal is greater than 0, decreasing the amplitude of the periodic signal.

[0174] In addition, adjusting the frequency of the periodic signal using the phase difference comparison result specifically includes: if the phase of the predicted back electromotive force lags behind the phase of the current driving voltage waveform, then the frequency of the periodic signal is decreased; if the phase of the predicted back electromotive force leads the phase of the current driving voltage waveform, then the frequency of the periodic signal is increased.

[0175] The PWM signal is generated by the PWM modulator 25 using a periodic signal.

[0176] The linear resonant motor 3 is driven by the PWM signal converted into a voltage signal through the drive circuit 13.

[0177] Preferably, the linear resonant motor driving method disclosed in this embodiment of the invention further includes: determining whether the amplitude of the periodic signal reaches the maximum driving voltage allowed by the linear resonant motor by using the driving waveform DDS24; if the amplitude of the periodic signal reaches the maximum driving voltage allowed by the linear resonant motor, then the driving waveform DDS24 inputs the periodic signal to the PWM modulator 25, and drives the linear resonant motor using the maximum driving voltage signal via the driving circuit 13.

[0178] Furthermore, corresponding to the linear resonant motor drive system disclosed in the first embodiment of the present invention, the linear resonant motor drive method disclosed in this embodiment of the present invention further includes: determining whether the predicted back electromotive force is greater than a preset rated back electromotive force threshold by the amplitude protection module 26; if the predicted back electromotive force is greater than the preset rated back electromotive force threshold, then the amplitude protection is triggered and the drive circuit 3 is stopped; if the predicted back electromotive force is not greater than the preset rated back electromotive force threshold, then the amplitude protection is not triggered and the drive circuit 3 is not stopped.

[0179] During the operation of a linear resonant motor (LRA), its coils generate heat due to the applied excitation current. If the coils generate heat for an extended period and cannot dissipate it in time, it can lead to high temperatures inside the LRA, resulting in decreased amplitude control accuracy of the oscillator, noise, and even permanent damage.

[0180] Corresponding to the linear resonant motor drive system disclosed in the first embodiment of the present invention, the linear resonant motor drive method disclosed in this embodiment further includes: using the temperature calculation module 27 to calculate the predicted coil impedance R... TThe temperature T of the motor coil is calculated using the temperature calculation formula:

[0181]

[0182] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil.

[0183] The temperature protection module 28 determines whether the motor coil temperature T exceeds the preset temperature protection threshold. If the motor coil temperature T exceeds the preset temperature protection threshold, the temperature protection is triggered, and the drive circuit 3 is stopped. The module then determines whether the motor coil temperature T is less than the preset temperature protection release threshold. If the motor coil temperature T is less than the preset temperature protection release threshold, the drive circuit 3 is restored.

[0184] Furthermore, corresponding to the linear resonant motor drive system disclosed in the second embodiment of the present invention, the linear resonant motor drive method disclosed in this embodiment of the present invention further includes: generating a first amplitude input attenuation coefficient through the amplitude control module 29; calculating a first product of the first amplitude input attenuation coefficient and the input amplitude to obtain an adjusted input amplitude; and calculating the difference between the adjusted input amplitude and the predicted back electromotive force by the drive voltage controller 22 to obtain an error signal.

[0185] Further, the first amplitude input attenuation coefficient is greater than 0 and less than or equal to 1; the amplitude control module 29 determines whether the predicted peak value of the reverse electromotive force is higher than the first reverse electromotive force preset threshold Vth1; if the predicted peak value of the reverse electromotive force is higher than the first reverse electromotive force preset threshold Vth1, it determines whether the first duration for which the predicted peak value of the reverse electromotive force is higher than the first reverse electromotive force preset threshold Vth1 has reached the first preset time t1; if the first duration has reached the first preset time t1, the first amplitude input attenuation coefficient is reduced; it determines whether the predicted peak value of the reverse electromotive force is less than the second reverse electromotive force preset threshold Vth2; if the predicted peak value of the reverse electromotive force is less than the second reverse electromotive force preset threshold Vth2, it determines whether the second duration for which the predicted peak value of the reverse electromotive force is less than the second reverse electromotive force preset threshold Vth2 has reached the second preset time t2; if the second duration has reached the second preset time t2, the first amplitude input attenuation coefficient is increased.

[0186] During the operation of a linear resonant motor (LRA), its coils generate heat due to the applied excitation current. If the coils generate heat for an extended period and cannot dissipate it in time, it can lead to high temperatures inside the LRA, resulting in decreased amplitude control accuracy of the oscillator, noise, and even permanent damage.

[0187] Corresponding to the linear resonant motor drive system disclosed in the second embodiment of the present invention, the linear resonant motor drive method disclosed in this embodiment further includes: using the temperature calculation module 27 to calculate the predicted coil impedance R... T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0188]

[0189] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil.

[0190] The temperature protection module 28 determines whether the motor coil temperature T exceeds the preset temperature protection threshold. If the motor coil temperature T exceeds the preset temperature protection threshold, the temperature protection is triggered, and the drive circuit 3 is stopped. The module then determines whether the motor coil temperature T is less than the preset temperature protection release threshold. If the motor coil temperature T is less than the preset temperature protection release threshold, the drive circuit 3 is restored.

[0191] Furthermore, corresponding to the linear resonant motor drive system disclosed in the third embodiment of the present invention, the linear resonant motor drive method disclosed in this embodiment of the present invention further includes: determining whether the predicted back electromotive force is greater than a preset rated back electromotive force threshold by the amplitude protection module 26; if the predicted back electromotive force is greater than the preset rated back electromotive force threshold, then the amplitude protection is triggered and the drive circuit 3 is stopped; if the predicted back electromotive force is not greater than the preset rated back electromotive force threshold, then the amplitude protection is not triggered and the drive circuit 3 is not stopped.

[0192] During the operation of a linear resonant motor (LRA), its coils generate heat due to the applied excitation current. If the coils generate heat for an extended period and cannot dissipate it in time, it can lead to high temperatures inside the LRA, resulting in decreased amplitude control accuracy of the oscillator, noise, and even permanent damage.

[0193] Corresponding to the linear resonant motor drive system disclosed in the third embodiment of the present invention, the linear resonant motor drive method disclosed in this embodiment further includes: using the temperature calculation module 27 to calculate the predicted coil impedance R... T The temperature T of the motor coil is calculated using the temperature calculation formula:

[0194]

[0195] Among them, R 25 The coil impedance, T, is at 25℃. coef It is the temperature coefficient of the motor coil.

[0196] The temperature control module 210 generates a second amplitude input attenuation coefficient; the second product of the second amplitude input attenuation coefficient and the input amplitude is calculated to obtain the adjusted input amplitude; the difference between the adjusted input amplitude and the predicted back electromotive force is calculated by the drive voltage controller 22 to obtain the error signal.

[0197] Wherein, the second amplitude input attenuation coefficient is greater than 0 and less than or equal to 1. The temperature control module 210 determines whether the motor coil temperature T is higher than a first preset temperature threshold T1; if the motor coil temperature T is higher than the first preset temperature threshold T1, it determines whether the third duration of the motor coil temperature T being higher than the first preset temperature threshold T1 reaches a third preset time t3; if the third duration reaches the third preset time t3, the second amplitude input attenuation coefficient is decreased; it then determines whether the motor coil temperature T is less than a second preset temperature threshold T2; if the motor coil temperature T is less than the second preset temperature threshold T2, it determines whether the fourth duration of the motor coil temperature T being less than the second preset temperature threshold T2 reaches a fourth preset time t4; if the fourth duration reaches the fourth preset time t4, the second amplitude input attenuation coefficient is increased.

[0198] The above three embodiments of the present invention are merely illustrative examples of the various functional modules, elements, and devices, and do not limit the scope of protection of the present invention by the above combinations. Any combination of functional modules, elements, and devices described in the above embodiments falls within the scope of protection claimed by the present invention.

[0199] Compared with existing technologies, the linear resonant motor driving method provided in this application, based on IV detection, can detect the driving voltage V and driving current I of the linear resonant motor in real time without stopping the driving circuit. Using an adaptive sliding mode observer or an adaptive Luenberger observer, the back electromotive force and coil impedance of the linear resonant motor can be estimated in real time, thereby achieving real-time estimation of the motor coil resistance value R. T Real-time estimation of the induced electromotive force (BEMF) improves the accuracy of F0 tracking and LRA amplitude control. Even if factors such as interface plugging / unplugging, ambient temperature changes, and motor long-term vibration temperature rise cause changes in R, these can be detected in real time to ensure the correct BEMF detection value. Furthermore, the linear resonant motor driving method disclosed in this embodiment can also implement amplitude protection, amplitude control, temperature protection, and temperature control functions.

[0200] In this embodiment of the invention, since the detection of the driving voltage V and the driving current I does not stop the driving waveform, the defects of the prior art can be avoided, such as poor amplitude consistency, parasitic diode conduction of the power transistor, and audio noise.

[0201] In this embodiment of the invention, because the back electromotive force (BEMF) information can be detected in real time, rather than only at the zero-crossing point, higher precision and speed control of the linear resonant motor can be achieved. This mainly includes:

[0202] It eliminates high-order harmonics in the drive voltage waveform caused by zero-crossing window detection;

[0203] Real-time control of the oscillator speed of the linear resonant motor eliminates the inconsistency in the amplitude of the drive voltage waveform caused by zero-crossing window detection;

[0204] It eliminates the attenuation of drive voltage amplitude caused by zero-crossing window detection, and increases the maximum output amplitude by 10% to 20% under the same power supply voltage;

[0205] The parameter identification module is used to estimate and detect the motor coil resistance in real time, which solves the problem of the detection error of BEMF caused by the drift of motor coil resistance in traditional IV detection.

[0206] Adaptive sliding mode adaptive observer or adaptive Luneburg adaptive observer is used to track BEMF voltage, which reduces the amount of computation, increases the tracking speed, and improves system stability;

[0207] By using the parameter identification module to estimate the motor coil resistance in real time, and considering the temperature coefficient of the motor coil resistance, an estimated value of the real-time temperature of the motor coil resistance can be calculated. When the motor coil overheats, appropriate vibration stop protection or attenuation of the drive voltage waveform amplitude can be implemented to prevent motor coil failure due to overheating. When the motor coil temperature is low, the drive voltage waveform amplitude is increased to compensate for the attenuation of the oscillator amplitude caused by the increased viscosity coefficient of the magnetic fluid at low temperatures.

[0208] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A linear resonant motor drive method, characterized by, The method comprises: Real-time detecting driving voltage V and driving current I of the linear resonant motor without stopping driving; With the drive voltage V and the drive current I, the counter electromotive force and the coil impedance R during motor operation are predicted T ; Calculating difference between input amplitude and predicted back electromotive force to obtain error signal; Comparing phase difference between predicted back electromotive force and current driving voltage waveform to obtain phase difference comparison result; Generating periodic signal with variable amplitude and frequency, adjusting amplitude of the periodic signal by using the error signal, and adjusting frequency of the periodic signal by using the phase difference comparison result; Generating PWM signal by using the periodic signal; The PWM signal is converted into a voltage signal to drive the linear resonant motor; the driving voltage V and the driving current I are used to predict the counter electromotive force and the coil impedance R during the motor operation T , comprising: Based on the set initial estimate of the field current Obtaining the first negative number of the initial estimate of the motor coil resistance voltage drop and the initial estimate of the back electromotive force, which includes: calculating the difference between the initial driving current I(t0) and the initial estimate of the field current by a two-input subtractor, obtaining the initial error of the field current estimate The observation unit uses adaptive sliding mode observer gain K or adaptive Luenberger observer gain L d , the initial error of the field current estimate is processed, specifically, the observation unit multiplies the initial error of the field current estimate by K after sgn() operation as output, or the observation unit directly multiplies the initial error of the field current estimate by L as output d ; the observation unit calculates the product of the processed initial error of the field current estimate and the second gain L by a second amplifier to obtain the first negative number of the initial estimate of the back electromotive force​ calculating an excitation current estimate for the first time instant using the drive voltage V(t1) at the first time instant, the first phase opposition number, and the initial estimate of the motor coil resistance voltage drop the driving current I(t1) at the first time instant and the estimated value of the field current the estimated value of the motor coil resistance at the first time instant and the second inverse of the estimated value of the back electromotive force, the estimated value of the motor coil resistance at the first time instant is the predicted coil impedance R at the first time instant T ; wherein the second inverse of the estimated value of the back electromotive force at the first time instant is calculated, and the specific steps include: calculating the difference between the driving current I(t1) at the first time instant and the estimated value of the field current by the two-input subtractor to obtain the estimated error of the field current at the first time instant and sending the estimated error of the field current at the first time instant to the observation unit; processing the estimated error of the field current at the first time instant by the observation unit using the adaptive sliding mode observer gain K or the adaptive Luenberger observer gain L d , specifically, the observation unit multiplies the estimated error of the field current by K after sgn() operation as the output, or the observation unit directly multiplies the estimated error of the field current by L d as the output; calculating the product of the processed estimated error of the field current at the first time instant and the second gain L by the second amplifier to obtain the second inverse of the estimated value of the back electromotive force at the first time instant; Calculate the estimated value of the motor coil resistance at the first moment. With excitation current estimate The second product yields the estimated value of the motor coil resistance voltage drop at the first moment; Based on the second opposite number and the motor coil resistance voltage drop estimation value calculated at the previous moment, combined with the driving voltage V(t n ) at the current moment, the excitation current estimation value at each subsequent moment is obtained using the drive current I(t n ) and the estimated value of the field current at the subsequent individual time points and the second inverse of the estimated value of the counter electromotive force at the subsequent individual time points , the estimated value of the coil impedance R T at the subsequent individual time points computing a motor coil resistance estimate for each of the subsequent time instants a second product of the field current estimate to obtain a motor coil resistance voltage drop estimate for each of the subsequent time instants Calculating first product of second phase opposite number and -1 at each time; and After filtering ripple generated by adaptive observer based on the first product, obtaining and outputting back electromotive force estimation value at each time, wherein the back electromotive force estimation value is predicted back electromotive force.

2. A method of driving a linear resonant motor as defined in claim 1, characterized by Adjusting amplitude of the periodic signal by using the error signal comprises: Comparing size of the error signal and 0 value; If the error signal is less than 0, increasing amplitude of the periodic signal; If the error signal is greater than 0, decreasing amplitude of the periodic signal.

3. A method of driving a linear resonant motor as defined in claim 2, wherein The method further comprises: Judging whether amplitude of the periodic signal reaches maximum driving voltage allowed by the linear resonant motor; If amplitude of the periodic signal reaches maximum driving voltage allowed by the linear resonant motor, driving the linear resonant motor by using maximum driving voltage signal.

4. A method of driving a linear resonant motor as defined in claim 1, wherein Adjusting frequency of the periodic signal by using the phase difference comparison result comprises: If phase of predicted back electromotive force lags behind phase of current driving voltage waveform, decreasing frequency of the periodic signal; If phase of predicted back electromotive force leads phase of current driving voltage waveform, increasing frequency of the periodic signal.

5. A method of driving a linear resonant motor as claimed in any one of claims 1 to 4, characterized in that, The method further comprises: Judging whether predicted back electromotive force is greater than preset rated back electromotive force threshold value; If predicted back electromotive force is greater than preset rated back electromotive force threshold value, triggering amplitude protection and stopping driving circuit; If predicted back electromotive force is not greater than preset rated back electromotive force threshold value, not triggering amplitude protection and not stopping driving circuit.

6. A method of driving a linear resonant motor as defined in claim 5, wherein The method further comprises: Generating first amplitude input attenuation coefficient; Calculating first product of the first amplitude input attenuation coefficient and the input amplitude to obtain adjusted input amplitude; Calculating difference between the adjusted input amplitude and predicted back electromotive force to obtain error signal; Wherein, the first amplitude input attenuation coefficient is greater than 0 and less than or equal to 1; Judging whether predicted back electromotive force peak value is higher than first back electromotive force preset threshold value Vth1; If predicted back electromotive force peak value is higher than first back electromotive force preset threshold value Vth1, judging whether first duration that predicted back electromotive force peak value is higher than first back electromotive force preset threshold value Vth1 reaches first preset time t1; If first duration reaches first preset time t1, decreasing the first amplitude input attenuation coefficient; Judging whether predicted back electromotive force peak value is less than second back electromotive force preset threshold value Vth2; If the predicted peak value of the back electromotive force is less than the second back electromotive force preset threshold Vth2, it is determined whether a second duration that the predicted peak value of the back electromotive force is less than the second back electromotive force preset threshold Vth2 reaches a second preset time t2. If the second duration reaches the second preset time t2, the first amplitude input attenuation coefficient is increased.

7. A method of driving a linear resonant motor as claimed in any one of claims 1 to 4, characterized in that, The method further comprises: Based on the predicted coil impedance R T , the motor coil temperature T is calculated using a temperature calculation formula: wherein R 25 is the coil impedance at 25 °C, T coef is the temperature coefficient of the motor coil; It is determined whether the motor coil temperature T exceeds a preset temperature protection threshold value; If the motor coil temperature T exceeds the preset temperature protection threshold value, temperature protection is triggered, and the driving circuit is stopped; It is determined whether the motor coil temperature T is less than a preset temperature protection release threshold value; If the motor coil temperature T is less than the preset temperature protection release threshold value, the driving circuit is restored.

8. A method of driving a linear resonant motor as defined in claim 7, wherein The method further comprises: A second amplitude input attenuation coefficient is generated; A second product of the second amplitude input attenuation coefficient and the input amplitude is calculated to obtain an adjusted input amplitude; A difference between the adjusted input amplitude and the predicted peak value of the back electromotive force is calculated to obtain an error signal; The second amplitude input attenuation coefficient is greater than 0 and less than or equal to 1; It is determined whether the motor coil temperature T is higher than a first temperature preset threshold value T1; If the motor coil temperature T is higher than the first temperature preset threshold value T1, it is determined whether a third duration that the motor coil temperature T is higher than the first temperature preset threshold value T1 reaches a third preset time t3; If the third duration reaches the third preset time t3, the second amplitude input attenuation coefficient is decreased; It is determined whether the motor coil temperature T is less than a second temperature preset threshold value T2; If the motor coil temperature T is less than the second temperature preset threshold value T2, it is determined whether a fourth duration that the motor coil temperature T is less than the second temperature preset threshold value T2 reaches a fourth preset time t4; If the fourth duration reaches the fourth preset time t4, the second amplitude input attenuation coefficient is increased.

9. A linear resonant motor drive system characterized by, The system comprises: An analog circuit part and a digital circuit part, the analog circuit part comprising: a current detection ADC, a voltage detection ADC, a driving circuit; the digital circuit part comprising: an adaptive observer with parameter identification, a driving voltage controller, an F0 detection module, a driving waveform DDS, a PWM modulator; The current detection ADC is used to detect the driving current I of the linear resonant motor in real time without stopping the driving; The voltage detection ADC is used to detect the driving voltage V of the linear resonant motor in real time without stopping the driving; The adaptive observer is configured to predict the back electromotive force and the coil impedance R during operation of the motor using the drive voltage V and the drive current I T ; The driving voltage controller is used to calculate a difference between the input amplitude and the predicted peak value of the back electromotive force to obtain an error signal; The F0 detection module is used to compare a phase difference between the predicted peak value of the back electromotive force and a current driving voltage waveform to obtain a phase difference comparison result; The driving waveform DDS is used to generate a periodic signal with variable amplitude and frequency, adjust the amplitude of the periodic signal by using the error signal, and adjust the frequency of the periodic signal by using the phase difference comparison result; The PWM modulator is used to generate a PWM signal by using the periodic signal; The driving circuit is used for driving the linear resonant motor by converting the PWM signal into a voltage signal; Using the drive voltage V and the drive current I, the counter electromotive force and the coil impedance R during the motor operation are predicted T comprising: Based on the set initial estimate of the excitation current Obtaining the first negative of the initial estimated values ​​of the motor coil resistance voltage drop and the initial estimated values ​​of the back electromotive force includes: calculating the initial drive current I(t0) and the initial estimated value of the excitation current using a two-input subtractor. The difference is used to obtain the initial error of the excitation current estimation. The observation unit utilizes either the adaptive sliding mode observer gain K or the adaptive Lumberjack observer gain L. d Initial error in estimating excitation current The process involves processing the initial error of the excitation current estimation by the observation unit. Perform the sgn() operation and then multiply by K as the output, or the observation unit can directly estimate the initial error using the excitation current. Multiply by L d As the output, the product of the initial error of the processed excitation current estimate and the second gain L is calculated by the second amplifier to obtain the first negative number of the initial estimate of the back electromotive force. calculating an excitation current estimate for the first time instant using the drive voltage V(t1) for the first time instant, the first phase opposition number, and the initial estimate of the motor coil resistance voltage drop the first moment of time using the drive current I(t1) and the excitation current estimate value calculating the motor coil resistance estimate value at the first moment of time and the second opposite number of the back electromotive force estimate value, the motor coil resistance estimate value at the first moment of time is the predicted coil impedance R at the first moment of time T ; wherein the second opposite number of the back electromotive force estimate value at the first moment of time is calculated, and the specific steps include: calculating the difference between the drive current I(t1) at the first moment of time and the excitation current estimate value by the two-input subtractor to obtain the excitation current estimation error at the first moment of time and sending the excitation current estimation error at the first moment of time to the observation unit; using the adaptive sliding mode observer gain K or the adaptive Luenberger observer gain L d , the observation unit processes the excitation current estimation error at the first moment of time , specifically, the observation unit performs sgn() operation on the excitation current estimation error and then multiplies it by K as the output, or the observation unit directly multiplies the excitation current estimation error by L d as the output; the second amplifier calculates the product of the processed excitation current estimation error at the first moment of time and the second gain L to obtain the second opposite number of the back electromotive force estimate value at the first moment of time; computing a first estimate of the motor coil resistance at the first time instant a second product of the field current estimate to obtain a first estimate of the motor coil resistance voltage drop at the first time instant Based on the second opposite number and the motor coil resistance voltage drop estimation value calculated at the previous moment, combined with the driving voltage V(t n ) at the current moment, the excitation current estimation value at each subsequent moment is obtained using the drive current I(t n ) and the estimated value of the field current at the subsequent individual time points and the second inverse of the estimated value of the back electromotive force at the subsequent individual time points T ; computing a motor coil resistance estimate for each of the subsequent time instants a second product of the field current estimate to obtain a motor coil resistance voltage drop estimate for each of the subsequent time instants calculating a first product of a second reciprocal and -1 at each time point; and After filtering out ripple generated by self-adaptive observer chattering based on the first product, obtaining and outputting an estimated value of counter electromotive force at each time point, wherein the estimated value of counter electromotive force is a predicted counter electromotive force.

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