A charge pump correction driving method for piezoelectric actuator

Abstract

The present invention discloses a charge pump correction drive method for a piezoelectric actuator. The method utilizes a reference voltage module to generate positive and negative reference voltages; a logic comparison module to generate a control signal f1 for the reference voltage module; a switched capacitor module to control the rate of change of charge across the piezoelectric actuator; a hysteresis correction module to generate a varying voltage signal to control a voltage-frequency conversion module; and a voltage-frequency conversion module to generate a control signal f2 for the switched capacitor module. The correction parameters of the hysteresis correction module are obtained by fitting a second-order polynomial to the output hysteresis curve of a classic charge pump drive. The present invention can achieve simple adjustment of the output displacement range and frequency. When the drive voltage range is 0 to 100V, the hysteresis of the piezoelectric actuator can be significantly reduced to below 0.47% based on a classic charge pump drive, thereby significantly improving the hysteresis nonlinearity of the piezoelectric actuator and possessing significant application value.

Description

Technical Field

[0001] The present invention relates to the field of precision micro-displacement platforms, and specifically to a charge pump correction driving method for a piezoelectric actuator. The method uses a logic comparison module, a switched capacitor charge pump, and a hysteresis correction module to achieve a low-hysteresis piezoelectric actuator driving method in which the output displacement frequency and displacement range of the piezoelectric actuator can be arbitrarily adjusted. Background Art

[0002] In the field of precision displacement platforms, nanometer-level precision is often required. Piezoelectric ceramics offer the advantages of small size, high resolution, fast frequency response, low noise, and high load-bearing capacity. However, piezoelectric ceramics inherently exhibit hysteresis and creep properties, which limit their accuracy when performing precision displacement. Hysteresis has the greatest impact on precision. Therefore, improving or reducing the hysteresis and nonlinearity of piezoelectric ceramics has become a crucial issue that needs to be addressed.

[0003] Currently, the main control methods for piezoelectric ceramics include open-loop feedforward control and feedback control based on voltage control, as well as charge control. The open-loop feedforward control method requires the establishment of an accurate nonlinear model, and the model is relatively complex, making it difficult to achieve high-precision control. While the feedback control method can achieve high-precision control, it requires a specialized high-precision displacement sensor to collect the output signal and simultaneously correct the drive signal in real time, resulting in a high system cost. The charge control method utilizes the characteristic that the displacement of the piezoelectric ceramic is approximately linear with the charge at both ends, which can reduce the hysteresis nonlinearity of the piezoelectric ceramic. However, this method lacks a DC path and is prone to output saturation. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of the above-mentioned prior art and provide a charge pump correction drive method for a piezoelectric actuator, so as to reduce the large hysteresis of traditional voltage drive and classic charge pump circuits while achieving arbitrary adjustment of the frequency and displacement range of the output displacement, thereby significantly improving the hysteresis nonlinearity of the piezoelectric actuator.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The charge pump correction driving method for a piezoelectric actuator of the present invention is characterized in that it is applied to a driving system composed of a reference voltage module, a switch capacitor module, a high-voltage operational amplifier module, a logic comparison module, a hysteresis correction module and a voltage-frequency conversion module, wherein the reference voltage module includes a voltage regulator chip and a single-pole double-throw analog switch S1, and the switch capacitor module includes a single-pole double-throw analog switch S2 and a capacitor C i The negative input terminal of the high voltage operational amplifier module is connected to the piezoelectric actuator C pThe negative end of the high voltage operational amplifier module is connected to one end of the single-pole double-throw analog switch S2; the positive input end of the high voltage operational amplifier module is grounded, and the output end of the high voltage operational amplifier module is connected to the piezoelectric actuator C p The charge pump correction driving method is performed according to the following steps:

[0007] Step 1: The reference voltage module uses a voltage regulator chip to generate positive and negative reference voltages, and switches the single-pole double-throw analog switch S1 according to the received square wave control signal f1, so that the positive reference voltage or the negative reference voltage is transmitted to the switched capacitor module; when in the initial state, the square wave control signal f1 is set to a low level, so that the reference voltage module transmits the negative reference voltage to the switched capacitor module through the single-pole double-throw analog switch S1;

[0008] Step 2: The switch capacitor module switches the single-pole double-throw analog switch S2 according to the received switch control signal f2. i When the single-pole double-throw analog switch S2 is connected to the reference voltage module, the reference voltage module is connected to the capacitor C i When the capacitor C i When the single-pole double-throw analog switch S2 is connected to the high-voltage operational amplifier module, the capacitor C i The charge is transferred to the piezoelectric actuator C through the high-voltage operational amplifier module p Both ends;

[0009] Step 3: The piezoelectric actuator C p The voltage V0 at both ends is transmitted to the logic comparison module, which compares the voltage V0 with two set voltage values. If the voltage V0 is lower than the set lower limit voltage, the logic comparison module generates a low-level square wave control signal f1 and transmits it to the reference voltage module and the hysteresis correction module respectively; if the voltage V0 is higher than the set upper limit voltage, the logic comparison module generates a high-level square wave control signal f1 and transmits it to the reference voltage module and the hysteresis correction module respectively;

[0010] Step 4: The hysteresis correction module judges the square wave control signal f1. If it is a high level, it generates a rising hysteresis signal with a slope of k1 to the voltage-frequency conversion module. If it is a low level, it generates a falling hysteresis signal with a slope of k2 to the voltage-frequency conversion module.

[0011] Step 5: The voltage-frequency conversion module generates a switching control signal f2 with a frequency change according to the received hysteresis signal and sends it to the switch capacitor module.

[0012] The charge pump correction driving method for a piezoelectric actuator according to the present invention is also characterized in that the hysteresis correction module controls the slope of the hysteresis signal in the following manner:

[0013] Step a, measuring the output hysteresis curve of the classic charge pump circuit and performing a second-order polynomial fitting to obtain an output displacement curve;

[0014] Step b, obtaining the slope of the output displacement k=2at+b after taking the first-order partial derivative of the output displacement curve; wherein b represents the reference parameter, a represents the correction parameter, and t represents the time;

[0015] Step c: by changing the frequency of the switch control signal f2, the switch capacitor module controls the piezoelectric actuator C p Nonlinearly changing charge signals are generated at both ends to eliminate the 2at term of the output displacement slope k, making the output displacement linear, thereby improving the hysteresis nonlinearity of the output displacement.

[0016] The correction parameter a in the hysteresis correction module is obtained as follows:

[0017] According to the output displacement curve, the reference parameter b1 and correction parameter a1 at a certain frequency F1 are determined; the reference parameter at another frequency F2 is b2 = b1 × F2 / F1, and the correction parameter a2 = a1 × (F2 / F1). 2 .

[0018] An electronic device of the present invention includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the charge pump correction driving method, and the processor is configured to execute the program stored in the memory.

[0019] The present invention provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium. The characteristic of the computer program is that when the computer program is executed by a processor, the steps of the charge pump correction driving method are executed.

[0020] Compared with the existing technology, the beneficial effects of the present invention are embodied in:

[0021] 1. The present invention proposes a charge pump correction driving method for a piezoelectric actuator, which solves the residual hysteresis problem of the piezoelectric actuator under the classic charge pump driving condition and greatly reduces the hysteresis nonlinearity problem of the piezoelectric actuator.

[0022] 2. The driving method shown in the present invention solves the problem that the output displacement frequency and range are difficult to control under the classic charge pump driving condition. By setting the upper and lower limit comparison voltages and controlling the switching frequency of the switch capacitor module, the output displacement frequency and range are easily adjustable.

[0023] 3. The driving method shown in the present invention uses a second-order polynomial to fit the classic charge pump drive output displacement curve. After determining the correction parameters of a certain frequency, the correction parameters of other frequencies can be determined. The correction process is simple and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the overall control scheme of the present invention;

[0025] Figure 2 This is the basic principle diagram of the classic charge pump driver;

[0026] Figure 3 This is the timing diagram of the logic comparison module;

[0027] Figure 4 This is the flow chart of the hysteresis correction module;

[0028] Figure 5 Figure 1 is a diagram of a charge pump device for calibration;

[0029] Figure 6a The hysteresis curve of the piezoelectric actuator driven by a classic charge pump is shown in Figure 2.

[0030] Figure 6b Figure 2 shows the hysteresis curve of a piezoelectric actuator driven by a calibrated charge pump. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0032] In this embodiment, a charge pump correction driving method for a piezoelectric actuator is provided. The overall control scheme is as follows: Figure 1 As shown, it is applied to a drive system composed of a reference voltage module, a switch capacitor module, a high-voltage operational amplifier module, a logic comparison module, a hysteresis correction module and a voltage-frequency conversion module, wherein, as Figure 2 As shown, the reference voltage module includes a voltage regulator chip and a single-pole double-throw analog switch S1, and the switch capacitor module includes a single-pole double-throw analog switch S2 and a capacitor C i , the negative input terminal of the high voltage operational amplifier module is connected to the piezoelectric actuator C p The negative end of the module is connected to one end of the single-pole double-throw analog switch S2; the positive input end of the high-voltage operational amplifier module is grounded, and the output end of the high-voltage operational amplifier module is connected to the piezoelectric actuator C p The positive terminal of the charge pump is connected; the charge pump correction driving method is carried out as follows:

[0033] Step 1: The reference voltage module uses a voltage regulator chip to generate positive and negative reference voltages, and switches the single-pole double-throw analog switch S1 according to the received square wave control signal f1, such as Figure 2As shown, the positive reference voltage or the negative reference voltage is transmitted to the switched capacitor module; when in the initial state, the square wave control signal f1 is set to a low level, so that the reference voltage module transmits the negative reference voltage to the switched capacitor module through the single-pole double-throw analog switch S1;

[0034] Step 2: The switched capacitor module switches the single-pole double-throw analog switch S2 according to the received switch control signal f2. Figure 2 As shown, when the capacitor C i When the single-pole double-throw analog switch S2 is connected to the reference voltage module, the reference voltage module is connected to the capacitor C i When the capacitor C i When the single-pole double-throw analog switch S2 is connected to the high-voltage operational amplifier module, the capacitor C i The charge is transferred to the piezoelectric actuator C through the high-voltage operational amplifier module p At both ends, by controlling the switching frequency of switch S2, the amount of charge and discharge per unit time of the switched capacitor module can be controlled, thereby adjusting the hysteresis nonlinearity of the piezoelectric actuator;

[0035] Step 3: Piezoelectric Actuator C p The voltage V0 across it is transmitted to the logic comparison module, such as Figure 3 As shown, the logic comparison module compares the voltage V0 with the two set voltage values. If the voltage V0 is lower than the set lower limit voltage, the logic comparison module generates a low-level square wave control signal f1 and transmits it to the reference voltage module and the hysteresis correction module respectively. The switch S1 switches to the negative reference voltage source, and the voltage at the output end of the piezoelectric actuator continuously increases. If the voltage V0 is higher than the set upper limit voltage, the logic comparison module generates a high-level square wave control signal f1 and transmits it to the reference voltage module and the hysteresis correction module respectively. When the output voltage is higher than the upper limit voltage, the logic comparison module outputs a high level, the switch S1 switches to the positive reference voltage source, and the voltage at the output end of the piezoelectric actuator continuously decreases. Automatic control of the output displacement range is achieved by controlling the switch S1.

[0036] Step 4: The hysteresis correction module judges the square wave control signal f1, such as Figure 4 As shown, if it is a high level, it generates a rising hysteresis signal with a slope of k1 to the voltage-frequency conversion module. If it is a low level, it generates a falling hysteresis signal with a slope of k2 to the voltage-frequency conversion module. Since the slopes of the adjustment signals for the forward and reverse strokes are different, in order to prevent the drift and distortion of the adjustment signal, a zeroing operation is performed after each adjustment of the forward and reverse strokes is completed.

[0037] Step 5: Figure 1 As shown, the voltage-frequency conversion module generates a switching control signal f2 with a frequency change according to the received hysteresis signal and sends it to the switch capacitor module.

[0038] In this embodiment, the hysteresis correction module controls the slope of the hysteresis signal in the following manner:

[0039] Step a: Measure the output hysteresis curve of the classic charge pump circuit and perform a second-order polynomial fit, such as Figure 6a As shown, the output displacement curve is obtained;

[0040] Step b, obtaining the slope of the output displacement k=2at+b after taking the first-order partial derivative of the output displacement curve; wherein b represents the reference parameter, a represents the correction parameter, and t represents the time;

[0041] Step c: by changing the frequency of the switch control signal f2, the switch capacitor module controls the piezoelectric actuator C p Nonlinearly changing charge signals are generated at both ends to eliminate the 2at term of the output displacement slope k, making the output displacement linear, thereby improving the hysteresis nonlinearity of the output displacement.

[0042] In a specific implementation, the correction parameter a in the hysteresis correction module is obtained as follows:

[0043] According to the output displacement curve, the reference parameter b1 and correction parameter a1 at a certain frequency F1 are determined; the reference parameter at another frequency F2 is b2 = b1 × F2 / F1, and the correction parameter a2 = a1 × (F2 / F1). 2 .

[0044] In this embodiment, an electronic device includes a memory and a processor. The memory is used to store a program that supports the processor to execute the above-mentioned charge pump correction driving method. The processor is configured to execute the program stored in the memory.

[0045] In this embodiment, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the charge pump correction driving method are executed.

[0046] Example 1: Corrected charge pump drive hysteresis measurement;

[0047] The piezoelectric actuator is driven by a classic charge pump driving method and a corrected charge pump driving method. The classic charge pump driving method uses a driving signal of 0 to 100V for driving, and the corrected charge pump driving method also uses a driving signal with upper and lower limits of 0 to 100V for driving. Figure 5As shown in the figure; the microcontroller generates correction parameters to control the charge and discharge rates of the charge pump; the output displacement signal of the piezoelectric actuator is monitored by an eddy current displacement sensor (Jianxing Technology, China), which has a measurement range of 50μm and a resolution of 0.72nm; and the eddy current output data is then collected and output by a data acquisition card (Simaikehua, USB-6000, China), which has a 24-bit resolution.

[0048] When the driving signal frequency is given as 1 Hz, the experimental results are shown in Figure 6. For a piezoelectric actuator driven by a classic charge pump, as Figure 6a , its hysteresis is 2.83%, while for the piezoelectric actuator using the corrected charge pump driving method, such as Figure 6b , its hysteresis is 0.33%, which is 88.34% lower than the hysteresis of the classic charge pump drive. It can be seen that the use of a corrected charge pump drive method can effectively reduce the hysteresis of the piezoelectric actuator in the forward and reverse stroke under the classic charge pump drive.

[0049] The experimental results of the remaining frequencies are shown in Table 1 below:

[0050] Table 1 Hysteresis size at different frequencies

[0051]

[0052] Where S1 is the hysteresis when using a classic charge pump drive; S2 is the hysteresis when using a corrected charge pump drive; k is the hysteresis reduction percentage;

[0053] In summary, compared with the classical charge pump drive, the method of the present invention has significantly improved the hysteresis nonlinearity and achieved simple control of the output displacement range and frequency, which has great application value in the fields of micro-nano measurement, precision drive, etc.

Claims

1. A charge pump correction driving method for a piezoelectric actuator, characterized in that: It is applied to a drive system composed of a reference voltage module, a switch capacitor module, a high-voltage operational amplifier module, a logic comparison module, a hysteresis correction module and a voltage-frequency conversion module, wherein the reference voltage module includes a voltage regulator chip and a single-pole double-throw analog switch S1, and the switch capacitor module includes a single-pole double-throw analog switch S2 and a capacitor C i The negative input terminal of the high voltage operational amplifier module is connected to the piezoelectric actuator C p The negative end of the high voltage operational amplifier module is connected to one end of the single-pole double-throw analog switch S2; the positive input end of the high voltage operational amplifier module is grounded, and the output end of the high voltage operational amplifier module is connected to the piezoelectric actuator C p The charge pump correction driving method is performed according to the following steps: Step 1: The reference voltage module uses a voltage regulator chip to generate positive and negative reference voltages, and switches the single-pole double-throw analog switch S1 according to the received square wave control signal f1, so that the positive reference voltage or the negative reference voltage is transmitted to the switched capacitor module; when in the initial state, the square wave control signal f1 is set to a low level, so that the reference voltage module transmits the negative reference voltage to the switched capacitor module through the single-pole double-throw analog switch S1; Step 2: The switch capacitor module switches the single-pole double-throw analog switch S2 according to the received switch control signal f2. i When the single-pole double-throw analog switch S2 is connected to the reference voltage module, the reference voltage module is connected to the capacitor C i When the capacitor C i When the single-pole double-throw analog switch S2 is connected to the high-voltage operational amplifier module, the capacitor C i The charge is transferred to the piezoelectric actuator C through the high-voltage operational amplifier module p Both ends; Step 3: The piezoelectric actuator C p The voltage V0 at both ends is transmitted to the logic comparison module, which compares the voltage V0 with two set voltage values. If the voltage V0 is lower than the set lower limit voltage, the logic comparison module generates a low-level square wave control signal f1 and transmits it to the reference voltage module and the hysteresis correction module respectively; if the voltage V0 is higher than the set upper limit voltage, the logic comparison module generates a high-level square wave control signal f1 and transmits it to the reference voltage module and the hysteresis correction module respectively; Step 4: The hysteresis correction module judges the square wave control signal f1. If it is a high level, it generates a rising hysteresis signal with a slope of k1 to the voltage-frequency conversion module. If it is a low level, it generates a falling hysteresis signal with a slope of k2 to the voltage-frequency conversion module. Step 5: The voltage-frequency conversion module generates a switching control signal f2 with a frequency change according to the received hysteresis signal and sends it to the switch capacitor module.

2. The charge pump correction driving method for a piezoelectric actuator according to claim 1, wherein: The hysteresis correction module controls the slope of the hysteresis signal in the following manner: Step a, measuring the output hysteresis curve of the classic charge pump circuit and performing a second-order polynomial fitting to obtain an output displacement curve; Step b, obtaining the slope of the output displacement k=2at+b after taking the first-order partial derivative of the output displacement curve; wherein b represents the reference parameter, a represents the correction parameter, and t represents the time; Step c: by changing the frequency of the switch control signal f2, the switch capacitor module controls the piezoelectric actuator C p Nonlinearly changing charge signals are generated at both ends to eliminate the 2at term of the output displacement slope k, making the output displacement linear, thereby improving the hysteresis nonlinearity of the output displacement.

3. The charge pump correction driving method for a piezoelectric actuator according to claim 2, wherein: The correction parameter a in the hysteresis correction module is obtained as follows: According to the output displacement curve, the reference parameter b1 and correction parameter a1 at a certain frequency F1 are determined; the reference parameter at another frequency F2 is b2 = b1 × F2 / F1, and the correction parameter a2 = a1 × (F2 / F1). 2 .

4. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the charge pump correction driving method according to claim 1, 2 or 3, and the processor is configured to execute the program stored in the memory.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the charge pump correction driving method according to claim 1, 2 or 3 are executed.

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