Ultrasonic motor micro driver based on self-oscillation principle and use method

Abstract

The invention relates to the technical field of ultrasonic motor driving, and discloses an ultrasonic motor micro driver based on a self-oscillation principle and a use method, the ultrasonic motor micro driver comprises an amplification circuit module, a voltage series negative feedback amplification circuit composed of an integrated operational amplifier, and an output end of the amplification circuit module is connected with a feedback network through an inductor; the temperature compensation module directly senses temperature change through an equivalent circuit of the ultrasonic motor and dynamically adjusts circuit parameters; and the frequency selection network module is composed of three impedance elements, and the impedance elements are respectively connected with the temperature compensation module, the amplification circuit module and the feedback network module. Through the self-oscillation principle and the feedback characteristic of the ultrasonic motor, a complex external frequency tracking loop is omitted, and simplification and miniaturization of circuit design are achieved. The driving frequency is automatically adjusted through the temperature compensation module, so that the adaptability to resonant frequency drift is realized; the power consumption is reduced and the driving efficiency is improved by optimizing the feedback network.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic motor driving, in particular to an ultrasonic motor micro-driver based on the self-excited oscillation principle and a use method thereof. Background Art

[0002] With the widespread application of ultrasonic motors in the field of precision control, its driving technology has become one of the key research directions. Traditional ultrasonic motor driving technology usually relies on an external resonant circuit, which generates a pulse signal of a specific frequency and applies it to both ends of the motor. It uses the friction between the piezoelectric stator and the rotor to convert the microscopic vibration of the stator into the macroscopic rotation of the rotor, thereby realizing the driving function. This technology has important applications in medical equipment, industrial automation, aerospace and other fields.

[0003] However, in practical applications, temperature changes in existing technologies can cause the resonant frequency of ultrasonic motors to drift. Traditional methods require the addition of additional frequency tracking loops, which not only complicates the design of the drive circuit, but also limits the miniaturization and integration of the driver. On the other hand, traditional drivers rely on fixed-amplitude signals, which make it difficult to maintain the stability of the drive signal under dynamic changes in load and temperature, resulting in low operating efficiency and reliability. In addition, the frequency adjustment response of existing external resonant circuits is slow, making it difficult to meet rapidly changing environmental requirements, significantly limiting their applicability in high-precision and multi-operating environments. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an ultrasonic motor micro-driver and a method of use based on the self-excited oscillation principle, which solves the problems of frequency drift, complex design and signal instability caused by temperature changes and load fluctuations in the prior art.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an ultrasonic motor micro-driver based on the self-excited oscillation principle and a method of using the same, comprising:

[0006] The amplifier circuit module is a voltage series negative feedback amplifier circuit composed of an integrated operational amplifier, and its output end is connected to the feedback network through an inductor;

[0007] The temperature compensation module directly senses temperature changes through the equivalent circuit of the ultrasonic motor and dynamically adjusts the circuit parameters;

[0008] A frequency selection network module, composed of three impedance elements, which are respectively connected to the temperature compensation module, the amplifier circuit module and the feedback network module, and are used to dynamically adjust the drive signal frequency to match the resonant frequency of the ultrasonic motor;

[0009] The feedback network module includes at least two diodes with opposite directions, forming a dynamic stable control loop of the signal amplitude.

[0010] Preferably, the temperature compensation module is composed of an equivalent circuit of an ultrasonic motor, and the equivalent circuit is composed of a first resistor and a first capacitor in parallel, and the impedance thereof changes with temperature and directly affects the parameter adjustment of the frequency selection network.

[0011] Preferably, the frequency selection network module includes:

[0012] The first impedance part is composed of a first resistor and a first capacitor connected in parallel, one end of which is connected to the temperature compensation module, and the other end of which is connected to the second capacitor;

[0013] The second impedance is formed by the second capacitor alone;

[0014] The third impedance part is composed of a third resistor and a third capacitor connected in parallel.

[0015] Preferably, the output frequency f of the frequency selection network o Satisfies the following formula:

[0016]

[0017] in:

[0018] L is the inductance between the amplifier circuit and the frequency selection network;

[0019] C eq It is the equivalent capacitance and is affected by the equivalent impedance of the ultrasonic motor temperature compensation module.

[0020] Preferably, the feedback network module includes:

[0021] A nonlinear control circuit formed by connecting two diodes in opposite directions in parallel;

[0022] The second resistor and the fourth resistor are connected in series to the diode parallel circuit;

[0023] The feedback gain is adjusted to be greater than 3 through resistors at the beginning of oscillation, and the feedback signal amplitude is limited by diode conduction after the oscillation stabilizes.

[0024] Preferably, the amplifying circuit module comprises:

[0025] An integrated operational amplifier, wherein the non-inverting input terminal is connected to the frequency selection network, the inverting input terminal is connected to the feedback network, and the output terminal is connected to the feedback network through an inductor;

[0026] The amplifier circuit module is designed with dual power supplies, and the positive and negative voltages are equal, so as to provide symmetrical output signals.

[0027] The method for using the ultrasonic motor micro-actuator based on the self-excited oscillation principle comprises the following steps:

[0028] Amplifying the driving signal using the amplifier circuit module of the driver;

[0029] The temperature compensation module senses the temperature change of the ultrasonic motor and adjusts its equivalent impedance;

[0030] The frequency selection network dynamically adjusts the drive signal frequency according to the feedback signal provided by the temperature compensation module;

[0031] The feedback network adjusts the amplitude and stability of the oscillation signal and outputs a driving signal that matches the resonant frequency of the ultrasonic motor.

[0032] Preferably, the temperature compensation module adjusts the dynamic response time of the driving signal frequency to be 1 ms to 10 ms.

[0033] Preferably, the feedback network controls the amplitude of the oscillation signal by adjusting the conduction voltage of the diode, so that the total harmonic distortion rate of the output signal is lower than 1%.

[0034] Preferably, the frequency range of the driving signal is between 20kHz and 40kHz, and the amplitude of the output signal is stabilized in the range of 3V to 12V.

[0035] The present invention provides an ultrasonic motor micro-driver based on the self-excited oscillation principle and a method of using the same. The invention has the following beneficial effects:

[0036] 1. The present invention utilizes the equivalent circuit of the ultrasonic motor as a temperature compensation module, which can sense the influence of the ambient temperature and the internal temperature rise of the motor on the resonant frequency in real time, and dynamically adjust the drive signal frequency through the self-excited oscillation circuit to always match the motor resonant frequency. Compared with the traditional method that relies on external temperature control or independent tracking circuit, the present invention does not require additional sensors or complex circuit design, greatly improves the adaptability and accuracy of the driver, and can achieve stable operation in multiple temperature environments.

[0037] 2. The present invention introduces the self-excited oscillation principle into the design of ultrasonic motor drivers, and through the organic combination of the frequency selection network and the feedback network, directly realizes the automatic frequency tracking function without the need to additionally design a resonant frequency tracking loop or a compensation control module. This design significantly reduces the number of circuit components and reduces the system complexity, making the driver smaller in size and more suitable for highly integrated and miniaturized application scenarios, such as medical equipment, precision instruments and other space-sensitive fields.

[0038] 3. The present invention optimizes the nonlinear control mechanism in the feedback network and utilizes the synergistic effect of diodes and resistors in opposite directions to ensure that the amplitude of the driving signal remains stable in a dynamic environment, thereby avoiding the phenomenon of signal amplitude loss of control when the temperature fluctuates or the load changes in traditional drivers. In addition, the self-excited oscillation mechanism is used to achieve precise matching of the driving signal frequency with the motor resonant frequency, which significantly improves energy utilization and stabilizes the driving efficiency at more than 90%. Compared with traditional drivers, it significantly reduces energy consumption and improves operational reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a circuit diagram of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Please see attached Figure 1 The embodiment of the present invention provides an ultrasonic motor micro-driver based on the self-excited oscillation principle, including an amplification circuit module, a temperature compensation module, a frequency selection network module and a feedback network module.

[0042] 1. Overall structure of the driver

[0043] Amplifier circuit module

[0044] The amplifier circuit module is composed of an integrated operational amplifier, adopts a voltage series negative feedback structure, and is powered by a dual power supply (the positive and negative power supply pins are connected to equal positive and negative voltages respectively).

[0045] The non-inverting input terminal of the integrated operational amplifier is connected to the frequency selection network, the inverting input terminal is connected to the feedback network, and the output terminal is connected to the feedback network through the inductor L, which is used to amplify the sinusoidal excitation signal and provide stable driving energy for oscillation.

[0046] Temperature compensation module

[0047] The temperature compensation module is composed of an equivalent circuit of the ultrasonic motor, and its equivalent circuit is a loop of a first resistor (R1) and a first capacitor (C1) in parallel. When the motor operation causes the temperature to rise, its equivalent impedance (including resistance and capacitance) drifts with the temperature change.

[0048] The temperature compensation module acts on the frequency selection network and the feedback network through the dynamic change of equivalent parameters to achieve real-time matching of the drive signal frequency and the motor resonant frequency.

[0049] Frequency Selective Network Module

[0050] The frequency selection network module consists of three parts:

[0051] The first part (Z1): consists of a temperature compensation module (a parallel circuit of R1 and C1) and a second capacitor (C2), one end of which is connected to the output end of the amplifier circuit, and the other end is connected to the non-inverting input end of the integrated operational amplifier;

[0052] The second part (Z2): consists of a separate second capacitor (C2) for further adjusting the signal frequency;

[0053] The third part (Z3) is composed of a third resistor (R3) and a third capacitor (C3) connected in parallel, one end of which is connected to the non-inverting input terminal of the operational amplifier, and the other end is grounded.

[0054] The frequency selection network dynamically adjusts the drive signal frequency according to the change of the motor's equivalent impedance to keep it consistent with the motor's resonant frequency.

[0055] Feedback Network Module

[0056] The feedback network is composed of two diodes (D1, D2) with opposite directions connected in parallel with a second resistor (R2) and connected in series with a fourth resistor (R4).

[0057] In the early stage of oscillation, due to the small signal, the diodes are disconnected, and the feedback gain is controlled by R2 and R4, so that the amplification factor is greater than 3, and the oscillation starts quickly. After the oscillation stabilizes, one of the diodes is turned on, R2 is short-circuited, and the amplification factor is limited to the set range, ensuring the stability of the amplitude of the output signal.

[0058] 2. Working principle of the drive

[0059] Oscillation Generation and Frequency Tracking

[0060] The driver generates the driving signal through self-excited oscillation. The ultrasonic motor is both a signal receiver and a participant in the feedback signal. In the early stage of oscillation, the amplifier circuit and the frequency selection network work together to guide the frequency of the driving signal to a frequency close to the resonant frequency of the motor.

[0061] When the temperature changes during the operation of the motor cause the resonant frequency to drift, the equivalent impedance of the temperature compensation module changes accordingly. The frequency selection network dynamically adjusts its impedance value to follow the changes in the resonant frequency in real time, ensuring that the drive signal is always consistent with the motor resonant frequency.

[0062] Dynamic control of signal amplitude

[0063] The feedback network adjusts the signal amplitude through the nonlinear characteristics of the diode. When the signal is small, the diode is disconnected, the feedback gain is large, and the oscillation condition is quickly reached; when the signal amplitude increases to the set threshold, the diode is turned on, limiting the feedback gain, ensuring the amplitude of the output signal is stable, and avoiding overshoot or distortion.

[0064] 3. Driver core parameters and formula limitations

[0065] During the driving process, the frequency f of the driving signal o Satisfies the following formula relationship:

[0066]

[0067] in:

[0068] L is the inductance value, which is used for energy storage and oscillation stability;

[0069] C eq is the equivalent capacitance, which represents the dynamic capacitance value determined by the temperature compensation module (R1 and C1 in parallel) and other impedance elements in the frequency selection network.

[0070] Equivalent capacitance C eq The calculation formula is:

[0071]

[0072] Where C1 and C2 are the values ​​of the relevant capacitors in the temperature compensation module and the frequency selection network respectively.

[0073] The amplitude of the driving signal V o Controlled by the feedback network, its upper limit is determined by the following formula:

[0074]

[0075] Where V th is the forward voltage of the diode.

[0076] 4. Optimized design and effect of the driver

[0077] Through the above design, this driver has the following advantages:

[0078] Automatic frequency tracking: No additional frequency tracking circuit is required, dynamic frequency adjustment can be achieved directly through the temperature compensation module and frequency selection network.

[0079] Miniaturization and high integration: All core modules are integrated into compact circuits, suitable for miniaturized application scenarios.

[0080] High precision and high stability: frequency error is less than 1%, and output signal harmonic distortion rate is less than 1%.

[0081] Adapt to various temperature environments: The temperature compensation module can work normally in the range of -20℃ to 80℃ to ensure the resonant frequency tracking capability.

[0082] 5. How to use the driver

[0083] Step 1: Power the amplifier circuit module of the driver through a dual power supply and connect it to the ultrasonic motor.

[0084] Step 2: When the motor is initially working, use the amplifier circuit and frequency selection network to quickly establish an oscillation signal.

[0085] Step 3: As the motor operating temperature changes, the temperature compensation module senses and dynamically adjusts the parameters of the frequency selection network to ensure that the drive signal frequency automatically tracks the resonant frequency.

[0086] Step 4: The feedback network controls the signal amplitude to be stable, and the output drive signal acts on both ends of the motor to drive the motor to run at the optimal frequency.

[0087] Example 1: Stability test of driving frequency under fixed temperature environment

[0088] Objective: To verify the drive frequency stability of the driver in a constant temperature environment.

[0089] Specific steps:

[0090] Step 1: At room temperature 25°C, connect the driver to a res =25kHz ultrasonic motor.

[0091] Step 2: The driver is powered by dual power supplies with positive and negative voltages of ±12V.

[0092] Step 3: Set the diode threshold voltage in the feedback network to 0.7V, the second resistor R2 = 10kΩ1, and the fourth resistor R4 = 30kΩ4.

[0093] Step 4: Monitor the drive frequency f using a frequency meter t and record the frequency fluctuation range within 10 minutes.

[0094] Process parameters:

[0095] Inductance L = 10mH, equivalent capacitance G = 0.01μF, feedback gain G = 3.

[0096] Drive signal amplitude V o =6V o =6V o .

[0097] Comparative Example 1: Use a traditional external resonant circuit to drive the ultrasonic motor and test the frequency stability under the same working conditions.

[0098] Example 2: Frequency tracking capability under dynamic temperature changes

[0099] Objective: To test the frequency auto-tracking performance of the drive under temperature variation conditions.

[0100] Specific steps:

[0101] Step 1: Connect the driver to the ultrasonic motor and set the initial resonant frequency f of the motor res =30kHz.

[0102] Step 2: Increase the ambient temperature gradually from 20°C to 80°C at a heating rate of 10°C / min.

[0103] Step 3: The equivalent impedance in the temperature compensation module is R1 = 2kΩ, C1 = 0.02μF; the frequency selection network parameters are C2 = 0.015μF, C3 = 0.01μF.

[0104] Step 4: Record the driver output frequency f through real-time frequency measurement equipment o and the motor resonant frequency f res deviation.

[0105] Process parameters:

[0106] Drive signal amplitude V o =8V, the feedback gain is initially set to 3 times.

[0107] Comparative Example 2: Use a traditional driver with external temperature compensation to test the frequency tracking capability under the same working conditions.

[0108] Example 3: Stability test under different load conditions

[0109] Objective: Verify the frequency and amplitude stability of the drive under different load conditions.

[0110] Specific steps:

[0111] Step 1: The driver is connected to the ultrasonic motor with a load ranging from 10g to 50g.

[0112] Step 2: Set the initial resonant frequency f res =35kHz, driver operating voltage ±15V, frequency selection network parameters Z1=2kΩ||0.02μF, Z2=0.02μF, Z3=3kΩ||0.01μF.

[0113] Step 3: Increase the load gradually, 10g at a time, and monitor the drive frequency f o and signal amplitude V o .

[0114] Step 4: Record the frequency drift and amplitude change.

[0115] Process parameters:

[0116] Inductance L=8mH, maximum amplitude of driving signal is 10V.

[0117] Comparative Example 3: Using a traditional resonant drive circuit to test the drive signal characteristics when the load changes.

[0118] Comparative Experimental Design

[0119] Target:

[0120] The frequency tracking capability, amplitude stability and efficiency of the driver based on the self-oscillation principle under different temperature and load conditions are tested, and compared with the traditional driver to highlight the advantages of the invention.

[0121] Experimental protocol:

[0122] Experimental conditions:

[0123] Ambient temperature range: 20℃-80℃.

[0124] Load range: 10g-50g.

[0125] Test time: 10 minutes for each set of conditions.

[0126] Experimental data record:

[0127] Frequency deviation (f o -f res ).

[0128] Amplitude change (ΔV o ).

[0129] Drive efficiency

[0130] Experimental data table:

[0131]

[0132]

[0133] According to the table: the frequency deviation of the driver of the present invention is controlled within ±3, which is much better than the traditional driver (deviation is as high as 20Hz); under dynamic temperature and load conditions, the signal amplitude change of the present invention is controlled within ±0.1V, while the amplitude fluctuation of the traditional driver is large; the driving efficiency of the present invention is generally higher than 90%, which is significantly better than the traditional driver.

[0134] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Ultrasonic motor micro-actuator based on the self-excited oscillation principle, characterized in that: include: The amplifier circuit module is a voltage series negative feedback amplifier circuit composed of an integrated operational amplifier, and its output end is connected to the feedback network through an inductor; The temperature compensation module directly senses temperature changes through the equivalent circuit of the ultrasonic motor and dynamically adjusts the circuit parameters; A frequency selection network module, composed of three impedance elements, which are respectively connected to the temperature compensation module, the amplifier circuit module and the feedback network module, and are used to dynamically adjust the drive signal frequency to match the resonant frequency of the ultrasonic motor; The feedback network module includes at least two diodes with opposite directions, forming a dynamic stable control loop of the signal amplitude.

2. The ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 1, characterized in that: The temperature compensation module is composed of an equivalent circuit of an ultrasonic motor, wherein the equivalent circuit is composed of a first resistor and a first capacitor connected in parallel, and the impedance thereof changes with temperature, which directly affects the parameter adjustment of the frequency selection network.

3. The ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 1, characterized in that: The frequency selection network module includes: The first impedance part is composed of a first resistor and a first capacitor connected in parallel, one end of which is connected to the temperature compensation module, and the other end of which is connected to the second capacitor; The second impedance is formed by the second capacitor alone; The third impedance part is composed of a third resistor and a third capacitor connected in parallel.

4. The ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 3, characterized in that: The output frequency f of the frequency selection network o Satisfies the following formula: in: L is the inductance between the amplifier circuit and the frequency selection network; C eq It is the equivalent capacitance and is affected by the equivalent impedance of the ultrasonic motor temperature compensation module.

5. The ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 1, characterized in that: The feedback network module comprises: A nonlinear control circuit formed by connecting two diodes in opposite directions in parallel; The second resistor and the fourth resistor are connected in series to the diode parallel circuit; The feedback gain is adjusted to be greater than 3 through resistors at the beginning of oscillation, and the feedback signal amplitude is limited by diode conduction after the oscillation stabilizes.

6. The ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 1, characterized in that: The amplifier circuit module comprises: An integrated operational amplifier, wherein the non-inverting input terminal is connected to the frequency selection network, the inverting input terminal is connected to the feedback network, and the output terminal is connected to the feedback network through an inductor; The amplifier circuit module is designed with dual power supplies, and the positive and negative voltages are equal, so as to provide symmetrical output signals.

7. A method for using an ultrasonic motor micro-actuator based on the self-excited oscillation principle, according to any one of claims 1 to 6, characterized in that: The following steps are involved: Amplifying the driving signal using the amplifier circuit module of the driver; The temperature compensation module senses the temperature change of the ultrasonic motor and adjusts its equivalent impedance; The frequency selection network dynamically adjusts the drive signal frequency according to the feedback signal provided by the temperature compensation module; The feedback network adjusts the amplitude and stability of the oscillation signal and outputs a driving signal that matches the resonant frequency of the ultrasonic motor.

8. The method for using the ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 7, characterized in that: The temperature compensation module adjusts the dynamic response time of the driving signal frequency to be 1 ms to 10 ms.

9. The method for using the ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 7, characterized in that: The feedback network controls the amplitude of the oscillation signal by adjusting the conduction voltage of the diode, so that the total harmonic distortion rate of the output signal is lower than 1%.

10. The method for using the ultrasonic motor micro-actuator based on the self-excited oscillation principle according to claim 7, characterized in that: The frequency range of the driving signal is between 20kHz and 40kHz, and the amplitude of the output signal is stable in the range of 3V to 12V.

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