A constant power driving method and system for piezoelectric devices

Abstract

The application discloses a constant-power driving method and system of a piezoelectric device, and belongs to the technical field of piezoelectric ceramic driving.The piezoelectric device is connected with different loads, and then the impedance curves under the loads are measured by frequency sweeping analysis; then the measured impedance curves are drawn in a graph, the intersection of the curves is observed, and thus the frequency corresponding to the intersection is obtained; finally, the driving frequency of the piezoelectric device is determined according to the frequency of the intersection, and the constant-power driving of the piezoelectric device can be realized at the frequencies; the constant-power input and output can be realized, and thus the input circuit, the power supply and the output end electronic equipment are effectively protected.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramic drive technology, and more specifically to a constant power drive method and system for piezoelectric devices. Background Technology

[0002] Piezoelectric ceramics possess advantages such as high power density, small size, light weight, and no electromagnetic interference, and have long been used as driving elements with a wide range of applications. Piezoelectric devices based on the direct and inverse piezoelectric effects of piezoelectric ceramics have been widely utilized, such as piezoelectric drives, piezoelectric motors, piezoelectric fans, and piezoelectric transformers. Piezoelectric devices typically need to operate in a resonant state; their electrical behavior is similar to a high-Q bandpass filter, and high power transmission capability can only be obtained when operating near the resonant frequency.

[0003] The electrical driving frequency of a piezoelectric device is its mechanical resonant frequency, determined by the material, shape, size, and output load of the piezoelectric structure. Therefore, piezoelectric devices place high demands on the driving circuit, limiting their applicable power range. Furthermore, inherent heat dissipation constraints further restrict their widespread application. To promote the use of piezoelectric devices, in addition to enhancing their existing performance, it is necessary to expand and apply their inherent characteristics. To this end, a constant power driving method and system for piezoelectric devices is proposed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: how to avoid sudden changes in drive current caused by load changes, thereby achieving short circuit protection, and provides a constant power drive method for piezoelectric devices.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution, and the present invention includes the following steps:

[0006] S1: Connect the load in parallel to the output of the piezoelectric device;

[0007] S2: Connect the impedance analyzer to the input terminal of the piezoelectric device, and select the measurement parameters and sweep frequency range;

[0008] S3: Read and export impedance curve data;

[0009] S4: Change the load to a different value and repeat steps S1-S3;

[0010] S5: Plot the impedance data under different load values ​​with the scanning frequency as the horizontal axis and the impedance value as the vertical axis, and find the intersection of the impedance curves.

[0011] S6: Select the voltage frequency at the intersection of the impedance curves as the driving frequency to drive the piezoelectric device with constant power.

[0012] Furthermore, in step S1, the piezoelectric device is a working structure made of piezoelectric ceramics, and the types of working structures include piezoelectric motors, piezoelectric pumps, piezoelectric sensors, piezoelectric transformers, piezoelectric actuators, and piezoelectric stacks.

[0013] Furthermore, in step S2, the types of measurement parameters selected include impedance, resistance, and reactance.

[0014] Furthermore, in step S2, the frequency sweep interval includes the operating frequency range of any operating mode.

[0015] Furthermore, in step S4, the intersection of impedance curves includes the intersection of impedance curves under different vibration modes, and the intersection of the resonant and anti-resonant frequencies of the same mode.

[0016] This invention also provides a constant power drive system for piezoelectric devices, which uses the above-described method to drive the piezoelectric devices at constant power, including:

[0017] The impedance frequency characteristic measurement module is used to perform frequency sweep analysis on the impedance of a piezoelectric device after it is connected to a load by selecting measurement parameters and frequency sweep range, and then exporting the obtained data.

[0018] The impedance curve intersection point determination module is used to connect loads of different values ​​to the output end of the piezoelectric device, repeat the impedance curve measurement work, and then plot the impedance curves measured by different load values ​​in the same two-dimensional rectangular coordinate system to determine the impedance curve intersection point.

[0019] The constant power drive module is used to select the voltage frequency at the intersection of the impedance curves as the drive frequency to drive the piezoelectric device with constant power.

[0020] The control processing module is used to issue instructions to other modules to complete corresponding actions;

[0021] The impedance frequency characteristic measurement module, the impedance curve intersection point determination module, and the constant power drive module are all communicatively connected to the control processing module.

[0022] Compared with the prior art, the present invention has the following advantages: the constant power driving method and system for the piezoelectric device first connects the piezoelectric device to different loads, and then performs frequency sweep analysis to measure the impedance curves under each load; then, the measured impedance curves are plotted on a graph, and the intersection points of the curves are observed to obtain the frequency corresponding to the intersection points; finally, the driving frequency of the piezoelectric device is determined according to the frequency of the intersection points, and constant power driving of the piezoelectric device can be achieved at these frequencies; constant power input and output can be realized, thereby effectively protecting the input circuit, power supply and output electronic equipment. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the implementation of the constant power driving method for piezoelectric devices in Embodiment 2 of the present invention;

[0024] Figure 2 This is an impedance curve of a piezoelectric device with loads of 100Ω, 200Ω, 300Ω and 1000Ω respectively, and a frequency range of 86 to 96kHz in Embodiment 2 of the present invention.

[0025] Figure 3 This is an input power diagram of a certain piezoelectric device in Embodiment 2 of the present invention when the driving frequency is the frequency at the intersection of the impedance curves and other frequencies. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] This embodiment provides a technical solution: a constant power driving method based on the intersection of piezoelectric device impedance curves, including the main parts such as measuring the frequency characteristics of piezoelectric device impedance, determining the intersection point of impedance curves, using the driving voltage frequency at the intersection point, and connecting the load circuit.

[0029] The specific explanation is as follows:

[0030] After the piezoelectric device is connected to the required load, the impedance of the device is analyzed by sweeping the frequency in the range near the resonant frequency of the working mode, and the obtained data is exported.

[0031] To determine the intersection of impedance curves, different loads need to be connected to the output end of the piezoelectric device, and the subsequent impedance curve measurement work is repeated. Then, the impedance curves measured by different loads are plotted in the same two-dimensional rectangular coordinate system to determine the intersection of the impedance curves.

[0032] The use of the driving (voltage) frequency at the intersection point includes the intersection point of the impedance curve under different vibration modes, the intersection point near the resonant and anti-resonant frequencies of the same mode, and the selection of different frequencies at the intersection point according to actual needs to achieve constant power drive.

[0033] The connection of the load circuit is used in the experimental stage to connect a load to the output terminal of the piezoelectric device, and in the actual use stage to replace it with the required electrical appliance.

[0034] In this embodiment, the piezoelectric device is a working structure made of piezoelectric ceramics, including but not limited to any of the following: piezoelectric motor, piezoelectric pump, piezoelectric sensor, piezoelectric transformer, piezoelectric actuator, and piezoelectric stack.

[0035] In this embodiment, the intersection of the impedance curves includes, but is not limited to, any of the following: near the resonant frequency, near the anti-resonant frequency, and near the frequency of other vibration modes.

[0036] In this embodiment, the measured characteristic parameters include any one of the following: impedance, resistance, and reactance.

[0037] To achieve the above objectives, the present invention proposes a constant power driving method based on the above, comprising the following steps:

[0038] Connect the load in parallel to the output of the piezoelectric device;

[0039] Connect the impedance analyzer to the input terminal of the piezoelectric device, select the measurement parameters, and select the operating frequency range that includes any operating mode for the sweep frequency range.

[0040] Read and export impedance curve data;

[0041] Change the load to a different value and repeat the above operation, generally three to five times;

[0042] Plot the impedance data under different load values ​​with the scanning frequency as the horizontal axis and the impedance value as the vertical axis, and find the intersection of the impedance curves.

[0043] In the actual driving of piezoelectric devices, under the condition that the voltage is reasonable, the voltage frequency at the intersection of the impedance curves can be selected as the driving frequency to achieve constant power driving of the piezoelectric device.

[0044] Example 2

[0045] like Figure 1As shown, this invention provides a constant power driving method for piezoelectric devices, including processes such as measuring the impedance frequency characteristics of the piezoelectric device, determining the intersection points of the impedance curves, using the driving voltage frequency at the intersection points, and connecting the load circuit. After connecting the piezoelectric device to the required load, the impedance of the device is analyzed by sweeping the frequency of the operating mode resonant frequency, and the obtained measurement parameter data is exported. Determining the intersection points of the piezoelectric device impedance curves requires connecting different loads to the output terminal of the piezoelectric device and repeating the subsequent impedance curve measurements. Then, the impedance curves measured for different loads are plotted in the same two-dimensional rectangular coordinate system to determine the intersection points. The use of the driving voltage frequency at the intersection points includes intersection points of the impedance curves under different vibration modes, and intersection points near the resonant and anti-resonant frequencies of the same mode. Different frequencies at the intersection points are selected according to actual needs to achieve constant power driving. For example, if the piezoelectric device needs to operate in the planar expansion mode and requires greater efficiency, the selected intersection point is the one with lower impedance near the resonant frequency of the planar expansion mode. The connection of the load circuit is used in the experimental stage to connect the load to the output terminal of the piezoelectric device, and in the actual use stage to replace it with the required electrical appliance.

[0046] like Figure 2 The figure shows the impedance curves of a piezoelectric device when connected to different loads. Four different load values ​​were selected: 100Ω, 200Ω, 300Ω, and 1000Ω, with a frequency sweep range of 86–96kHz. It can be clearly seen from the figure that the impedance curves at the input end of the piezoelectric device intersect at two points, A and B, when connected to the four different loads.

[0047] like Figure 3 The figure shows graphs plotted with load resistance on the x-axis (range 0–700Ω) and input power on the y-axis for driving frequencies f1 and f3 (88.960kHz and 94.924kHz, respectively, at the intersection of the impedance curves) and driving frequency f2 (92kHz, at other frequencies). It is clear that when the driving frequency is the intersection of the impedance curves, the input power does not change with the load, achieving constant power driving of the piezoelectric device. However, when other frequencies are used as the driving frequencies, the input power of the piezoelectric device changes significantly.

[0048] In summary, the constant power driving method for piezoelectric devices described in the above embodiments first connects the piezoelectric device to different loads, then performs frequency sweep analysis to measure the impedance curves under each load; then plots the measured impedance curves on a graph, observes the intersection points of the curves, and obtains the frequencies corresponding to the intersection points; finally, determines the driving frequency of the piezoelectric device based on the frequencies of the intersection points, and at these frequencies, constant power driving of the piezoelectric device can be achieved; constant power input and output can be realized, thereby effectively protecting the input circuit, power supply, and output electronic equipment.

[0049] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A constant power driving method for a piezoelectric device, characterized in that, Includes the following steps: S1: Connect the load in parallel to the output of the piezoelectric device; S2: Connect the impedance analyzer to the input terminal of the piezoelectric device, and select the measurement parameters and sweep frequency range; S3: Read and export impedance curve data; S4: Change the load to a different value and repeat steps S1-S3; S5: Plot the impedance data under different load values ​​with the scanning frequency as the horizontal axis and the impedance value as the vertical axis, and find the intersection of the impedance curves. S6: Select the voltage frequency at the intersection of the impedance curves as the driving frequency to drive the piezoelectric device with constant power.

2. The constant power driving method for a piezoelectric device according to claim 1, characterized in that: In step S1, the piezoelectric device is a working structure made of piezoelectric ceramics. The types of working structures include piezoelectric motors, piezoelectric pumps, piezoelectric sensors, piezoelectric transformers, piezoelectric actuators, and piezoelectric stacks.

3. The constant power driving method for a piezoelectric device according to claim 1, characterized in that: In step S2, the types of measurement parameters selected include impedance, resistance, and reactance.

4. The constant power driving method for a piezoelectric device according to claim 1, characterized in that: In step S2, the frequency sweep interval includes the operating frequency range of any operating mode.

5. The constant power driving method for a piezoelectric device according to claim 1, characterized in that: In step S4, the intersection of impedance curves includes the intersection of impedance curves under different vibration modes, and the intersection of the resonant and anti-resonant frequencies of the same mode.

6. A constant power drive system for a piezoelectric device, characterized in that, The method described in any one of claims 1 to 5 is used to drive the piezoelectric device to constant power, comprising: The impedance frequency characteristic measurement module is used to perform frequency sweep analysis on the impedance of a piezoelectric device after it is connected to a load by selecting measurement parameters and frequency sweep range, and then exporting the obtained data. The impedance curve intersection point determination module is used to connect loads of different values ​​to the output end of the piezoelectric device, repeat the impedance curve measurement work, and then plot the impedance curves measured by different load values ​​in the same two-dimensional rectangular coordinate system to determine the impedance curve intersection point. The constant power drive module is used to select the voltage frequency at the intersection of the impedance curves as the drive frequency to drive the piezoelectric device with constant power. The control processing module is used to issue instructions to other modules to complete corresponding actions; The impedance frequency characteristic measurement module, the impedance curve intersection point determination module, and the constant power drive module are all communicatively connected to the control processing module.

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