Ultrasonic motor drive voltage feedback compensation system and method

Abstract

The present invention discloses an ultrasonic motor driving voltage feedback compensation system and method, comprising S1: collecting the real-time voltage of the ultrasonic motor driving end and processing it to obtain a sampled voltage; S2: collecting the ambient temperature in real time; S3: calculating a PWM modulation signal based on the comparison result of the sampled voltage and a reference voltage value, and combining the comparison result of the ambient temperature and a preset temperature value; S4: generating a PWM signal with a duty cycle of D according to the PWM modulation signal, and then outputting a dynamic voltage according to the PWM signal.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to an ultrasonic motor drive voltage feedback compensation system and method. Background Art

[0002] An ultrasonic motor is a motor that uses the inverse piezoelectric effect of piezoelectric materials to make the elastomer (stator) produce microscopic mechanical vibrations in the ultrasonic frequency band (vibration frequency is above 20kHz), and through the friction between the stator and the rotor (or mover), the microscopic mechanical vibrations of the stator are converted into macroscopic unidirectional rotation (or linear motion) of the rotor (or mover).

[0003] Ultrasonic motors are widely used in micro-intelligent ammunition due to their small structure, small footprint, and high reliability. However, under low temperature (-40°C) conditions, ultrasonic motors have two defects: on the one hand, the friction coefficient of the stator and mover of the ultrasonic motor changes due to thermal expansion and contraction of the material, resulting in a decrease in the preload between the stator and mover; on the other hand, the capacitance of the ultrasonic motor decays to 19 / 30 of that at room temperature (20°C) under low temperature (-40°C) conditions.

[0004] Therefore, under the combined effect of the above two defects, the output torque of the ultrasonic motor decreases, causing the ultrasonic motor to be unable to track the rudder control instructions or even to fail to move, thereby affecting the guidance control accuracy. Summary of the invention

[0005] In view of the problem in the prior art that the output torque of an ultrasonic motor decreases under low temperature conditions, the present invention proposes a system and method for driving voltage feedback compensation of an ultrasonic motor.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An ultrasonic motor drive voltage feedback compensation system includes a first loop and a second loop; wherein:

[0008] The first circuit is used to emit a square wave voltage to realize sinusoidal wave excitation of the ultrasonic motor; the second circuit is used to perform PWM adjustment on the output dynamic voltage according to the ultrasonic motor driving voltage, so as to control the output voltage value of the first circuit.

[0009] Preferably, the first circuit includes a signal generating module 11, a power amplifying module 12, a transformer 13, and a resonant circuit 14; the output end of the signal generating module 11 is connected to the input end of the power amplifying module 12, the output end of the power amplifying module 12 is connected to the first input end of the transformer 13, the output end of the transformer 13 is connected to the input end of the resonant circuit 14, and the output end of the resonant circuit 14 is connected to the driving end of the ultrasonic motor.

[0010] Preferably, the signal generating module 11 adopts a PSOC chip of specification model Cypress CY8C4014SXI-421, which is used to generate four square wave voltages with two phases differing by 90° and two complementary outputs per phase, namely, the first voltage;

[0011] The power amplifier module 12 uses an ATA-4011 chip to amplify the power of the first voltage to obtain a second voltage;

[0012] The signal specification of the transformer 13 is PT0106A, and is used to isolate and boost the second voltage to obtain a third voltage;

[0013] The resonant circuit 14 is used to filter out the harmonic components in the third voltage to achieve sinusoidal wave excitation of the ultrasonic motor.

[0014] Preferably, the second loop includes a temperature acquisition module 21, a voltage sampling module 22, a PID controller 23, a PWM generator 24, a DC / DC module 25 and a DC power supply module 26;

[0015] The input end of the voltage sampling module 22 is connected to the driving end of the ultrasonic motor, the output end of the temperature acquisition module 21 and the output end of the voltage sampling module 22 are respectively connected to the input end of the PID controller 23, the output end of the PID controller 23 is connected to the input end of the PWM generator 24, the output end of the PWM generator 24 is connected to the first input end of the DC / DC module 25, the output end of the DC power supply module 26 is connected to the second input end of the DC / DC module 25, and the output end of the DC / DC module 25 is connected to the second input end of the transformer 13 in the first loop.

[0016] Preferably, the temperature acquisition module 21 uses a chip thermistor, model NCP03.

[0017] Preferably, the voltage sampling module 22 includes a DC isolation unit, a voltage dividing unit, a rectifying unit and a voltage amplifying unit;

[0018] The input end of the DC isolation and AC unit is connected to the driving end of the ultrasonic motor, the output end of the DC isolation and AC unit is connected to the input end of the voltage divider unit, the output end of the voltage divider unit is connected to the input end of the rectifier unit, the output end of the rectifier unit is connected to the input end of the voltage amplifier unit, and the output end of the voltage amplifier unit is connected to the input end of the PID controller 23.

[0019] The present invention also provides an ultrasonic motor driving voltage feedback compensation method, which specifically comprises the following steps:

[0020] S1: Collect the real-time voltage of the ultrasonic motor driving end and process it to obtain the sampled voltage;

[0021] S2: real-time collection of ambient temperature;

[0022] S3: Calculate and obtain a PWM modulation signal based on the comparison result between the sampled voltage and the reference voltage value and the comparison result between the ambient temperature and the preset temperature value;

[0023] S4: Generate a PWM signal with a duty cycle of D according to the PWM modulation signal, and then output a dynamic voltage according to the PWM signal.

[0024] Preferably, the S1 includes:

[0025] S1-1: using a DC isolation and AC unit to isolate and AC the voltage at the motor driving end to obtain a fourth voltage;

[0026] S1-2: using a voltage dividing unit to perform AC voltage division on the fourth voltage to obtain a fifth voltage;

[0027] S1-3: using a rectifying unit to perform half-wave rectification on the fifth voltage to obtain a sixth voltage;

[0028] S1-4: A voltage amplification unit is used to amplify the sixth voltage after half-wave rectification to obtain a seventh voltage, so as to complete the voltage sampling of the motor drive end.

[0029] Preferably, in S3, the PWM modulation signal is calculated as follows:

[0030]

[0031] In formula (1), u ( k ) is the PWM modulation signal, K p , K i , K d is the proportionality coefficient, e1 ( k ) is the difference between the sampling voltage and the reference voltage in time period k, e 2( k ) is the difference between the sampled ambient temperature and the preset temperature value in time period k, Δt is the sampling time interval, i is the number of samplings, and K represents the total number of samplings; e 1( i ) Indicates the difference between the sampled voltage and the reference voltage during time period i; e 2( i ) Indicates the difference between the sampled ambient temperature and the preset temperature value during time period i; e 1( k-1 ) represents the difference between the sampled voltage and the reference voltage in time period k-1; e 2( k-1 ) It shows the difference between the sampled ambient temperature in time period k-1 and the preset temperature value.

[0032] Preferably, the S4 includes:

[0033] S4-1: The PWM generator generates a PWM signal with a duty cycle of D according to the PWM modulation signal:

[0034]

[0035] In formula (2), D represents the duty cycle; V avg is the sampled average voltage, V cc S4-2: Under the control of PWM signal, the DC / DC module outputs dynamic voltage U1:

[0036] U1=D×V cc1 (3)

[0037] In formula (3), U1 represents the dynamic voltage output by the DC / DC module; D represents the duty cycle; V cc1 Indicates the output voltage of the DC power module.

[0038] In summary, due to the adoption of the above technical solution, compared with the prior art, the present invention has at least the following beneficial effects:

[0039] The present invention overcomes the performance attenuation problem of electronic components, especially capacitors, in low temperature environments through voltage compensation, thereby improving output torque;

[0040] At the same time, it makes up for the problem of reduced pre-pressure caused by the change of friction coefficient due to thermal expansion and contraction of ultrasonic motor materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of an ultrasonic motor drive voltage feedback compensation system according to an exemplary embodiment of the present invention.

[0042] Figure 2 FIG. 4 is a schematic diagram of the structure of a voltage sampling module according to an exemplary embodiment of the present invention.

[0043] Figure 3 Schematic diagram of a voltage feedback compensation method for driving an ultrasonic motor according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with the examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0045] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] like Figure 1 As shown, the present invention provides an ultrasonic motor driving voltage feedback compensation system, comprising a first loop 1 and a second loop 2; wherein the first loop 1 is a main loop, used to emit a square wave voltage to realize sinusoidal wave excitation of the ultrasonic motor; the second loop 2 is a feedback compensation loop, used to perform PWM adjustment to output a dynamic voltage according to the ultrasonic motor driving voltage, thereby controlling the input voltage value of the first loop 1, realizing the voltage gain adjustment of the ultrasonic motor driving end, and completing the dynamic compensation of the resonant voltage floating caused by the capacitance change of the ultrasonic motor.

[0047] In this embodiment, the first loop 1 includes a signal generating module 11, a power amplifying module 12, a transformer 13, and a resonant circuit 14; the output end of the signal generating module 11 is connected to the input end of the power amplifying module 12, the output end of the power amplifying module 12 is connected to the first input end of the transformer 13, the output end of the transformer 13 is connected to the input end of the resonant circuit 14, and the output end of the resonant circuit 14 is connected to the driving end of the ultrasonic motor.

[0048] The signal generating module 11 (which may adopt a PSOC chip with specification model number of Cypress CY8C4014SXI-421) is used to generate four-way square wave voltage with two phases differing by 90° and two complementary outputs per phase, namely, the first voltage;

[0049] The power amplifier module 12 (using an ATA-4011 chip) is used to perform power amplification on the four-way square wave voltage (the first voltage) to obtain a second voltage;

[0050] The transformer 13 is used to isolate and boost the second voltage to obtain a third voltage; the specification model of the transformer 13 is PT0106A, the turns ratio is 1:10, and the driving voltage thereof can reach above 600V at low temperature (-40°C);

[0051] The resonant circuit 14 is an existing circuit, which uses an inductor L and a capacitive piezoelectric ceramic element C of the ultrasonic motor to form a resonant LC, filter out the harmonic components in the third voltage, and realize the sinusoidal wave excitation of the ultrasonic motor.

[0052] In this embodiment, the second loop 2 includes a temperature acquisition module 21, a voltage sampling module 22, a PID controller 23, a PWM generator 24, a DC / DC module 25 and a DC power supply module 26; the temperature acquisition module 21 is used to collect the ambient temperature, the input end of the voltage sampling module 22 is connected to the driving end of the ultrasonic motor, the output end of the temperature acquisition module 21 and the output end of the voltage sampling module 22 are respectively connected to the input end of the PID controller 23, the output end of the PID controller 23 is connected to the input end of the PWM generator 24, the output end of the PWM generator 24 is connected to the first input end of the DC / DC module 25, the output end of the DC power supply module 26 is connected to the second input end of the DC / DC module 25, and the output end of the DC / DC module 25 is connected to the second input end of the transformer 13 in the first loop 1.

[0053] The temperature acquisition module 21 (which may be a chip thermistor, model NCP03) is used to collect the ambient temperature signal in real time and send it to the PID controller 23;

[0054] The voltage sampling module 22 is used to collect the driving voltage of the driving end of the ultrasonic motor and feed it back to the PID controller 23.

[0055] The PID controller 23 is used to calculate and output a PWM modulation signal based on the comparison result between the driving voltage and the reference value, and the comparison result between the ambient temperature and the normal temperature value.

[0056] The PWM generator 24 is used to generate a PWM signal with a certain duty cycle according to the PWM modulation signal.

[0057] The DC / DC module 25 is used to dynamically adjust the voltage output according to the PWM signal, thereby controlling the transformer primary intermediate tap bus input voltage value; the DC / DC module 25 can select the switching regulator chip LM2678-ADJ, whose parameters are input voltage range: 4.5V~42V, adjustable output voltage, can provide up to 5A load current, and operating temperature is -40℃~+125℃.

[0058] The DC power module 26 is used to provide voltage input for the DC / DC module 25; a lithium battery or a thermal battery can be selected as the DC power module, and the input voltage range is 12V to 16V.

[0059] In this embodiment, Figure 2As shown, the voltage sampling module 22 includes a DC isolation AC unit, a voltage divider unit, a rectifier unit and a voltage amplification unit; the input end of the DC isolation AC unit is connected to the driving end of the ultrasonic motor, the output end of the DC isolation AC unit is connected to the input end of the voltage divider unit, the output end of the voltage divider unit is connected to the input end of the rectifier unit, the output end of the rectifier unit is connected to the input end of the voltage amplification unit, and the output end of the voltage amplification unit is connected to the input end of the PID controller.

[0060] Among them, the DC-to-AC isolation unit can use a chip ceramic capacitor (1kV / 100pF) to remove the DC voltage in the motor drive terminal voltage, retain the AC voltage, and mark the AC voltage as the fourth voltage;

[0061] The voltage divider unit may use a high voltage resistor (RI41 type high voltage resistor, which can withstand a voltage of 1kV) to divide the AC voltage output by the DC isolation unit to obtain a fifth voltage with a voltage range of 1V to 5V, so that the fifth voltage is adapted to the input range of the rectifier unit.

[0062] A rectifying unit, which may be a diode (1N4148), is used to perform half-wave rectification on the fifth voltage to obtain a sixth voltage;

[0063] The voltage amplification unit may adopt an operational amplifier (TLV2186, the operating voltage range of the device is 4.5V to 24V, and it plays the role of impedance transformation and signal isolation) for voltage following the sixth voltage to obtain the seventh voltage, so as to complete the voltage sampling of the motor drive end.

[0064] Based on the above system, the present invention also provides an ultrasonic motor drive voltage feedback compensation method, such as Figure 3 As shown, the specific steps include:

[0065] S1: Collect the real-time voltage of the ultrasonic motor driving end and process it to obtain the sampled voltage.

[0066] S1-1: using a DC isolation and AC unit to isolate and AC the voltage at the motor driving end to obtain a fourth voltage;

[0067] S1-2: using a voltage dividing unit to perform AC voltage division on the fourth voltage to obtain a fifth voltage;

[0068] S1-3: using a rectifying unit to perform half-wave rectification on the fifth voltage to obtain a sixth voltage;

[0069] S1-4: A voltage amplification unit is used to amplify the sixth voltage after half-wave rectification to obtain a seventh voltage (ie, a sampling voltage) to complete voltage sampling at the motor drive end.

[0070] S2: The sampling temperature acquisition module collects the ambient temperature in real time.

[0071] S3: Input the sampled voltage and the ambient temperature into the PID controller. According to the comparison result between the sampled voltage and the reference voltage value, and the comparison result between the ambient temperature and the preset temperature value (normal temperature value), the PWM modulation signal is calculated. The calculation formula is:

[0072]

[0073] In formula (1), u ( k ) is the PWM modulation signal, K p , K i , K d is the proportionality coefficient, e1 ( k ) is the difference between the sampling voltage and the reference voltage in time period k, e 2( k ) is the difference between the sampled ambient temperature and the preset temperature value in time period k, Δt is the sampling time interval, i is the number of samplings, and K represents the total number of samplings; e 1( i ) Indicates the difference between the sampled voltage and the reference voltage during time period i; e 2( i ) represents the difference between the sampled ambient temperature in time period i and the preset temperature value; e1(k-1) represents the difference between the sampled voltage in time period k-1 and the reference voltage value; e2(k-1) represents the difference between the sampled ambient temperature in time period k-1 and the preset temperature value;

[0074] S4: The PWM generator generates a PWM signal with a duty cycle of D according to the PWM modulation signal. The DC / DC module dynamically adjusts the voltage output according to the PWM signal, thereby controlling the primary intermediate tap bus input voltage value of the transformer to achieve voltage gain adjustment at the ultrasonic motor drive end, and complete dynamic compensation for the resonant voltage fluctuation caused by the capacitance change of the ultrasonic motor.

[0075] S4-1: The PWM generator generates a PWM signal with a duty cycle of D according to the PWM modulation signal:

[0076]

[0077] In formula (2), D represents the duty cycle; V avg is the sampled average voltage, V cc S4-2: The DC / DC module dynamically adjusts the output voltage U1 under the control of the PWM signal:

[0078] U1=D×V cc1 (3)

[0079] In formula (3), U1 represents the output voltage of the DC / DC module; D represents the duty cycle; Vcc1 Indicates the output voltage of the DC power module.

[0080] In this embodiment, the voltage U1 output in the second circuit and the third voltage U3 output by the transformer in the first circuit work together to make the LC resonance always operate in a relatively stable state, ensuring that the ultrasonic motor driving voltage gain is not affected by temperature and driving frequency, achieving stable output of driving voltage especially at low temperatures, thereby improving the output torque of the ultrasonic motor.

[0081] The principle is feedback regulation. When the temperature and driving frequency change, the output value U3 of the transformer 13 in the first circuit will be low. In order to keep the output value of the transformer 13 unchanged, the output voltage U1 in the second circuit is required to compensate U3. The two work together to make the LC resonance always work in a relatively stable state.

[0082] According to the above technical solution, a prototype of the guidance and control component was developed, and the ultrasonic motor, the prototype of the guidance and control component, and the test fixture were placed in a temperature test box. The test temperature was set at -40°C. The torque output value and the driving voltage amplitude of the test were displayed in real time by testing the upper computer operation of the industrial control computer. The weight method was used to dynamically test that under the above temperature conditions, the prototype of the guidance and control component drove the ultrasonic motor to drive the weight, and the speed of the ultrasonic motor was tested to determine whether the driving torque reached the specified value for verification.

[0083] The test results show that when the ultrasonic motor is driven to drive the torque load at low temperature (-40℃), the maximum torque sensor value of the test software can reach 0.4N·m. Compared with the torque value of 0.25N·m without the feedback compensation method, the output torque is increased by 60%, and the speed of the ultrasonic motor reaches more than 120 rpm; when the DC input terminal is adjusted to 16V, the maximum voltage drive amplitude of the ultrasonic motor reaches more than 600V. The test results show that this technical solution is feasible.

[0084] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. An ultrasonic motor drive voltage feedback compensation system, characterized in that: It includes a first loop and a second loop; wherein, The first circuit is used to emit a square wave voltage to realize sinusoidal wave excitation of the ultrasonic motor; the second circuit is used to perform PWM adjustment on the output dynamic voltage according to the ultrasonic motor driving voltage, so as to control the output voltage value of the first circuit.

2. The ultrasonic motor drive voltage feedback compensation system according to claim 1, characterized in that: The first loop comprises a signal generating module (11), a power amplifying module (12), a transformer (13), and a resonant circuit (14); the output end of the signal generating module (11) is connected to the input end of the power amplifying module (12), the output end of the power amplifying module (12) is connected to the first input end of the transformer (13), the output end of the transformer (13) is connected to the input end of the resonant circuit (14), and the output end of the resonant circuit (14) is connected to the driving end of the ultrasonic motor.

3. The ultrasonic motor drive voltage feedback compensation system according to claim 2, characterized in that: The signal generating module (11) adopts a PSOC chip of specification model Cypress CY8C4014SXI-421, and is used to generate four square wave voltages with two phases differing by 90° and two complementary outputs per phase, namely, the first voltage; The power amplifier module (12) adopts an ATA-4011 chip and is used to perform power amplification on the first voltage to obtain a second voltage; The signal specification of the transformer (13) is PT0106A, and is used to isolate and boost the second voltage to obtain a third voltage; The resonant circuit (14) is used to filter out harmonic components in the third voltage and realize sinusoidal wave excitation of the ultrasonic motor.

4. The ultrasonic motor drive voltage feedback compensation system according to claim 1, characterized in that: The second loop comprises a temperature acquisition module (21), a voltage sampling module (22), a PID controller (23), a PWM generator (24), a DC / DC module (25) and a DC power supply module (26); The input end of the voltage sampling module (22) is connected to the driving end of the ultrasonic motor, the output end of the temperature acquisition module (21) and the output end of the voltage sampling module (22) are respectively connected to the input end of the PID controller (23), the output end of the PID controller (23) is connected to the input end of the PWM generator (24), the output end of the PWM generator (24) is connected to the first input end of the DC / DC module (25), the output end of the DC power supply module (26) is connected to the second input end of the DC / DC module (25), and the output end of the DC / DC module (25) is connected to the second input end of the transformer (13) in the first loop.

5. The ultrasonic motor drive voltage feedback compensation system according to claim 4, characterized in that: The temperature acquisition module (21) adopts a chip thermistor, model NCP03.

6. The ultrasonic motor drive voltage feedback compensation system according to claim 4, characterized in that: The voltage sampling module (22) comprises a DC isolation unit, a voltage dividing unit, a rectification unit and a voltage amplification unit; The input end of the DC isolation and AC unit is connected to the driving end of the ultrasonic motor, the output end of the DC isolation and AC unit is connected to the input end of the voltage divider unit, the output end of the voltage divider unit is connected to the input end of the rectifier unit, the output end of the rectifier unit is connected to the input end of the voltage amplifier unit, and the output end of the voltage amplifier unit is connected to the input end of the PID controller (23).

7. A method for ultrasonic motor drive voltage feedback compensation based on the system according to any one of claims 1 to 6, characterized in that: The specific steps include: S1: Collect the real-time voltage of the ultrasonic motor driving end and process it to obtain the sampled voltage; S2: real-time collection of ambient temperature; S3: Calculate and obtain a PWM modulation signal based on the comparison result between the sampled voltage and the reference voltage value and the comparison result between the ambient temperature and the preset temperature value; S4: Generate a PWM signal with a duty cycle of D according to the PWM modulation signal, and then output a dynamic voltage according to the PWM signal.

8. The ultrasonic motor driving voltage feedback compensation method according to claim 7, characterized in that: The S1 includes: S1-1: using a DC isolation and AC unit to isolate and AC the voltage at the motor driving end to obtain a fourth voltage; S1-2: using a voltage dividing unit to perform AC voltage division on the fourth voltage to obtain a fifth voltage; S1-3: using a rectifying unit to perform half-wave rectification on the fifth voltage to obtain a sixth voltage; S1-4: A voltage amplification unit is used to amplify the sixth voltage after half-wave rectification to obtain a seventh voltage, so as to complete the voltage sampling of the motor drive end.

9. The ultrasonic motor driving voltage feedback compensation method according to claim 7, characterized in that: In S3, the PWM modulation signal is calculated as: In formula (1), u(k) is the PWM modulation signal, K p , K i , K d is the proportionality coefficient, e1(k) is the difference between the sampled voltage and the reference voltage value in time period k, e2(k) is the difference between the sampled ambient temperature and the preset temperature value in time period k, Δt is the sampling time interval, i is the number of samplings, and K is the total number of samplings; e1(i) represents the difference between the sampled voltage and the reference voltage value in time period i; e2(i) represents the difference between the sampled ambient temperature and the preset temperature value in time period i; e1(k-1) represents the difference between the sampled voltage and the reference voltage value in time period k-1; e2(k-1) represents the difference between the sampled ambient temperature in time period k-1 and the preset temperature value.

10. The ultrasonic motor driving voltage feedback compensation method according to claim 7, characterized in that: The S4 includes: S4-1: The PWM generator generates a PWM signal with a duty cycle of D according to the PWM modulation signal: In formula (2), D represents the duty cycle; V avg is the sampled average voltage, V cc is the sampling power supply voltage. S4-2: Under the control of the PWM signal, the DC / DC module outputs a dynamic voltage U1: U1=L×H cc1 (3) In formula (3), U1 represents the dynamic voltage output by the DC / DC module; D represents the duty cycle; V cc1 Indicates the output voltage of the DC power module.

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