CN105207518B - Time-sharing sequential driving multi-layer laminated piezoelectric driver rapid actuating method - Google Patents

Abstract

The invention provides a rapid actuating method of a time-sharing sequential driving multilayer laminated piezoelectric driver, which sequentially drives single-layer piezoelectric materials in a time-sharing manner according to the physical characteristics of wave propagation in a solid, drives the maximum deformation of each piece of piezoelectric ceramic in the multilayer piezoelectric driver to be simultaneously transmitted to the top end for linear superposition, and reduces mutual weakening of waves during propagation coupling in each piece of piezoelectric ceramic, thereby driving the multilayer piezoelectric driver to rapidly reach the maximum deformation. The invention is composed of a multilayer piezoelectric ceramic driver (1), a time sequence control module (2), a driving power supply module (3) and a quick switch (4), wherein the time sequence control module (2) controls the quick switch (4) to apply the driving power supply (3) to a single piece of piezoelectric ceramic (1) in sequence, so that each piece of piezoelectric ceramic reaches the maximum deformation at a specific moment, and the whole multilayer piezoelectric driver is driven to actuate quickly. The invention does not need to change the structure of the traditional multilayer piezoelectric driver, and has the advantages of quick actuation, large actuation displacement, wide application range, simple driving circuit, easy realization and the like.

Description

A fast actuation method for time-sharing and sequential driving of multilayer laminated piezoelectric actuators

technical field

The invention relates to the technical field of piezoelectric ultrasonic drive, in particular to a fast actuation method for time-sharing sequentially driving a multilayer laminated piezoelectric driver.

Background technique

Piezoelectric materials have the advantages of fast response speed, large output force, high energy conversion efficiency, and relatively simple control methods, and are often used as micro-displacement actuators. Among them, fast response speed is the most important advantage of piezoelectric actuators, and they are also widely used in fuel injectors, printers and other devices.

Due to the piezoelectric effect and the inverse piezoelectric effect, when a voltage is applied to the polarized piezoelectric material, the piezoelectric material will deform, and the deformation has a certain relationship with the applied voltage; due to the small strain of the single-piece piezoelectric material, for Some occasions that require high actuation speed and relatively large displacement, such as piezoelectric pumps, piezoelectric valves, etc., are usually actuated by piezoelectric stacks, that is, the method of multi-layer lamination is used to simultaneously drive the deformation of multiple piezoelectric materials to obtain Quick actuation. The control of multilayer piezoelectric actuators usually adopts the method of electrical parallel connection, that is, a control signal is applied to multiple piezoelectric materials at the same time, and multiple piezoelectric materials are simultaneously deformed by the driving signal to achieve fast and relatively large Displacement actuation. Since multiple sheets of laminated piezoelectric materials are deformed at the same time, the deformations of each layer of materials affect each other, and the deformations of the materials will weaken each other, so that the performance of each sheet of material cannot be fully utilized.

At present, the control methods for multilayer stacked piezoelectric actuators mainly focus on how to reduce the hysteresis and creep of the piezoelectric drive, improve the linearity of the displacement of the piezoelectric drive, and improve the displacement of the piezoelectric actuation. Most of these driving methods are from the perspective of electrical or automatic control principles to compensate or quantitatively control the driving electrical signal to achieve a higher driving linearity or a larger driving displacement. From the analysis of physical characteristics, there is no relevant report on the piezoelectric drive control method for improving the actuation speed and displacement of the piezoelectric drive by using the wave propagation theory.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention proposes a brand-new time-sharing sequential driving method to drive the piezoelectric driver, so as to obtain faster response and larger output displacement.

The present invention is realized through the following technical solutions: a time-sharing sequentially driving multilayer laminated piezoelectric ceramic driver fast actuation method, the method is composed of a multilayer laminated piezoelectric driver, a timing control module, a fast switch and a driving power supply module The system implementation of is characterized in that the implementation process includes:

Step 1), select a general-purpose multi-layer laminated piezoelectric driver, or design and manufacture a multi-layer laminated piezoelectric driver with a specific structure, the wave differential equation for wave propagation in a solid:

Among them, u is the displacement of the particle along the axial direction, E is the elastic modulus of the material, ρ is the density of the material, t is the time variable, and x is the position of the particle;

The propagation velocity of one-dimensional longitudinal wave in solid can be obtained as:

Wherein, E is the modulus of elasticity of the material, and ρ is the density of the material;

Step 2), according to the material properties and structural dimensions of the multilayer piezoelectric driver, calculate the propagation velocity of the wave and the time it travels in each layer of piezoelectric material, so as to obtain the pressure of each sheet of the wave in the multilayer piezoelectric driver The time difference transmitted on the electroceramic;

Step 3), according to the time difference of waves transmitted on each piece of piezoelectric ceramic in the multilayer piezoelectric driver, design a timing control module, so that the N output timing signals of the timing control module control the closing of the fast switch in turn, and drive the fast switch after it is closed. The power module is sequentially applied to the multilayer piezoelectric driver, so that the displacements generated by the piezoelectric ceramics in the multilayer laminated piezoelectric driver can be linearly superimposed, thereby realizing fast actuation. The multilayer laminated piezoelectric driver actuates The method greatly improves the actuation speed and actuation displacement of the multilayer piezoelectric actuator.

Wherein, the multilayer piezoelectric actuator with a specific structure is composed of several laminated piezoelectric ceramic sheets, and the upper and lower end surfaces of each ceramic sheet are plated with electrodes along the lamination direction; each ceramic sheet is connected to the same phase end surface after polarization treatment , forming a structural series connection and an electrical parallel connection.

Wherein, the timing control module is composed of N steady-state flip-flops and frequency dividers, and the N steady-state flip-flops are connected sequentially, the output terminal Q of the previous flip-flop is connected with the input terminal D of the next flip-flop, and the first The input of each flip-flop is connected to a high level; the clock signal CLK of the steady-state flip-flop is a high-frequency square wave with a frequency f input by the signal source, and the 1 terminal S of the steady-state flip-flop is connected to a low level uniformly, and the flip-flop The characteristics of N flip-flops Q ₀ ~ Q _N constitute a shifter, the time difference between each two sequences is controlled by the clock signal, and its value is 1/f second.

Wherein, the frequency divider in the timing control module is a commercially available common frequency divider, and the high-frequency square wave signal with a frequency of f is divided by the frequency divider to obtain a low-frequency signal with a frequency of f/2 ⁿ , which is used to control all triggers The set 0 terminal R determines the frequency of the control signal.

Wherein, the N fast switches in the fast switch module are commercially available MOS transistors, and fast electronic switching devices with equivalent performance can also be used.

The principle of the present invention is that: the present invention finds through the analysis of the structure of the multilayer piezoelectric ceramic driver and the process of stress wave propagation in it, the traditional direct drive method ignores that the driver is composed of multilayer piezoelectric ceramic layers. When the driver excites a pulse signal, the driver is regarded as a whole. But in fact, because the distance between each layer of piezoelectric ceramics and the top of the driver is different, when all the piezoelectric ceramic layers are excited at the same time, they will produce stress and deformation at the same time, so that each stress wave cannot propagate to the top of the driver at the same time, and there is a phase difference between them. And stress wave refraction and reflection will occur. Therefore, the traditional driving method will reduce the response speed of the driver, and the partial offset of the stress displacement will not be fully utilized. In the time-sharing driving method, the timing control module controls the power module to excite the corresponding piezoelectric ceramic layers at different times, so that the stress waves generated by all ceramic layers propagate to the top of the driver at the same time, and perform linear superposition. The time-sharing driving method can not only greatly improve the response speed of the multilayer piezoelectric ceramic driver, but also improve the output displacement of the driver.

The advantage of the present invention compared with prior art is:

(1), the present invention has fast response speed and can reach the maximum displacement output in a shorter time;

(2) The output displacement is large, and the experimental results show that the output displacement is about twice that of the prior art.

Description of drawings

Figure 1 is a schematic diagram of the time-sharing sequential drive of the laminated multilayer piezoelectric driver, where 1 is the multilayer piezoelectric ceramic driver, 2 is the timing control module, 3 is the driving power module, and 4 is the fast switch; the timing control module 2 According to the transmission speed of the wave in the piezoelectric material, the control signal is sequentially generated to control the on-off of the fast switch 4, and the fast switch 4 is sequentially turned on by the timing control signal, so that the driving power generated by the driving power module 3 is applied to each layer in sequence On the piezoelectric ceramic, the piezoelectric ceramic is driven to actuate quickly;

Fig. 2 is a schematic diagram of a single-group piezoelectric ceramic connection method and a 7-group piezoelectric ceramic connection method, wherein Fig. 2 (a) is a single-group piezoelectric ceramic connection method, and two piezoelectric ceramics are electrically connected in parallel according to the polarization direction; Fig. 2(b) is the connection comparison between the traditional control method and the timing control method. The traditional control method is to connect all the piezoelectric ceramics in parallel and control them with the same driving signal; apply drive voltage;

Figure 3 is a schematic diagram of the laminated multilayer piezoelectric ceramic timing control circuit; the clock signal generated by the signal source is respectively connected to the CLK terminal of the DQ flip-flop group and the input terminal of the CLK frequency divider, and the Q output terminal of the DQ flip-flop is connected to To the gate of the MOS tube, sequentially control the on-off of each MOS tube, thereby controlling the driving voltage on each group of piezoelectric ceramics;

Fig. 4 is a sequential hierarchical control sequence diagram;

Figure 5 is a comparison of output displacement curves of laminated multilayer piezoelectric ceramics driven by time-sharing sequence control and traditional control method.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the present invention provides a time-sharing and sequential driving method for fast actuation of multi-layer laminated piezoelectric actuators. According to the physical characteristics of medium-wave propagation in solids, the method drives single-layer piezoelectric materials in time-sharing and sequential driving to drive multiple The maximum deformation of each piece of piezoelectric ceramic in the multilayer piezoelectric actuator is transmitted to the top for linear superposition at the same time, and the wave weakens each other when propagating and coupling in each piece of piezoelectric ceramic, thereby driving the multilayer piezoelectric actuator to quickly reach the maximum deformation. The present invention is composed of a multilayer piezoelectric ceramic driver 1, a timing control module 2, a driving power supply module 3 and a fast switch module 4. The timing control module 2 controls the switching of the fast switch 4 so that the driving power supply 3 is sequentially applied to the monolithic piezoelectric ceramic 1 On the other hand, each piece of piezoelectric ceramic reaches the maximum deformation at a specific moment, thereby driving the entire multilayer piezoelectric actuator to actuate rapidly.

The specific implementation process of the time-sharing sequentially driving the fast actuation method of the multi-layer laminated piezoelectric driver includes the following steps:

Step 1), analyzing the process of stress wave propagation in the multilayer piezoelectric ceramic driver, the wave equation is as follows:

Among them, u is the displacement of the particle along the axial direction, E is the elastic modulus of the material, ρ is the density of the material, t is the time variable, and x is the position of the particle;

and the propagation velocity of a 1D longitudinal wave in a solid:

Wherein, E is the modulus of elasticity of the material, and ρ is the density of the material;

Step 2), according to the material properties and structural dimensions of the multilayer piezoelectric driver, calculate the propagation velocity of the wave and the time Δt=d/c ₀ it transmits in each layer of piezoelectric material;

Step 3), designing a timing control circuit module, which can generate a series of timing control signals, and the delay between adjacent timing pulses is equal to Δt, and has the same falling edge moment;

Step 4), the power supply control module provides DC high voltage, which is applied to each layer of piezoelectric ceramics through electronic switches;

Step 5), the timing control signal generated by the timing control module determines the on and off of the high voltage generated by the voltage module on each layer of piezoelectric ceramics by controlling the corresponding switch.

The time-sharing driving method mainly relies on a timing control module, a driving power supply module and a multilayer piezoelectric ceramic driver to realize it. In the following, an embodiment of the present invention will be described in detail by taking a driver composed of 14 layers of piezoelectric ceramics as an example.

As shown in Figure 2, Figure 2 is a schematic diagram of a single-group piezoelectric ceramic connection method and a 7-group piezoelectric ceramic connection method. The electrical parallel connection of the chemical direction; Fig. 2(b) is a connection comparison between the traditional control method and the sequential control method. The traditional control method is to connect all the piezoelectric ceramics in parallel and control them with the same driving signal; the sequential control method is to control each group of piezoelectric ceramics. The driving voltage is applied sequentially to the electric ceramics in time-sharing; in the right figure of Figure 2(b), 14 piezoelectric ceramics are divided into 7 groups, and the polarization directions of two adjacent piezoelectric ceramics are opposite. The positive electrode is drawn from the middle of each group of piezoelectric ceramics, and the negative electrode is drawn from the upper and lower surfaces; the positive electrodes of each group need to be connected to the driving voltage separately, and all the negative electrodes are connected to the power ground uniformly.

The time Δt required for the stress wave to pass through each layer of piezoelectric material is calculated by the wave equation, the characteristics of the piezoelectric material and the size of each group of piezoelectric ceramics, which is the delay time between the sequential circuit signals.

As shown in Figure 3, since there are 7 groups of drivers, 7 timing control signals need to be generated correspondingly. The timing control module requires the ability to generate timing pulses with a delay series, which is mainly realized by steady-state triggers.

Among them, seven steady-state flip-flops are connected sequentially, the output terminal Q of the previous flip-flop is connected with the input terminal D of the next flip-flop, and the input of the first flip-flop is connected to high level; the clock signal CLK of the steady-state flip-flop is controlled by The signal source inputs a high-frequency square wave with a frequency of f, and the 1-setting terminal S of the steady-state trigger is uniformly connected to a low level. According to the characteristics of the flip-flop, the output terminals Q ₁ ~ Q ₇ of the seven flip-flops constitute a shifter, and the time difference between each two sequences is controlled by the clock signal, and its value is 1/f second, setting f=1/△t ; The 0-setting terminal R of the steady-state trigger is controlled by a high-frequency square wave with a frequency of f and converted into a low-frequency signal with a frequency of f/2 ⁿ through a frequency divider, which determines that all timing pulses have the same falling edge time, which determines The frequency of the pulse signal.

As shown in Figure 3, the driving power module is mainly composed of high-voltage DC power supply, and the fast switch is mainly composed of commercially available MOS tubes. The high-voltage DC power supply excites each layer of piezoelectric ceramics through the D terminal of the corresponding MOS tube, and the seven pulse signals with timing difference generated by the timing control module control the G base of the corresponding MOS tube to determine the opening and closing of the electronic switch; the driver outputs The timing control waveform is shown in Figure 4.

The present invention is to stimulate each layer of piezoelectric ceramics of the multilayer piezoelectric ceramic driver in time-sharing order, so that the stress and deformation generated by them can be transmitted to the top of the driver at the same time, so that linear superposition can be performed; There is a certain phase difference in the stress wave generated by the electroceramic, and the stress will be partially offset, so that the response speed of the driver is reduced, and the output displacement is also reduced. The time-sharing drive can make the stress generated by each layer linearly superimpose quickly in a short period of time, greatly improving the response speed and displacement of the driver. Figure 5 shows the output waveform of the piezoelectric sheet strain.

The specific improvement of the present invention is that the response speed of the driver is no longer affected by the length of the driver and the level of the driving voltage. No matter how many layers of piezoelectric ceramics the driver consists of, it can linearly superimpose the stress generated by each layer without changing the response speed of the whole driver, as shown in Figure 5. In addition, according to the principle of time-sharing driving, the response speed of the driver will not change with the change of the driving voltage.

Claims (5)

1. A fast actuation method for time-sharing and sequentially driving a multilayer laminated piezoelectric ceramic driver, the method is composed of a multilayer laminated piezoelectric driver (1), a timing control module (2), a driving power supply module (3) and The system realization that fast switch (4) forms is characterized in that: realization process comprises: Step 1), select a general-purpose multi-layer laminated piezoelectric driver (1), or design and manufacture a multi-layer laminated piezoelectric driver (1) with a specific structure, the wave differential equation for wave propagation in a solid: Among them, u is the displacement of the particle along the axial direction, E is the elastic modulus of the material, ρ is the density of the material, t is the time variable, and x is the position of the particle; The propagation velocity of one-dimensional longitudinal wave in solid can be obtained as: Wherein, E is the modulus of elasticity of the material, and ρ is the density of the material; Step 2), according to the material properties and structural dimensions of the multilayer laminated piezoelectric driver, calculate the propagation speed of the wave and the time it travels in each layer of piezoelectric material, so that the wave in the multilayer laminated piezoelectric driver The time difference transmitted on each piece of piezoelectric ceramic; Step 3), according to the time difference of waves transmitted on each piece of piezoelectric ceramic in the multilayer laminated piezoelectric driver, design the timing control module (2), so that the N output timing signals of the timing control module (2) control the fast switch in sequence (4) is closed, and after the fast switch (4) is closed, the driving power supply module (3) is sequentially applied to the multi-layer laminated piezoelectric driver, so that each piece of piezoelectric ceramic in the multi-layer laminated piezoelectric driver (1) produces The displacement can be linearly superimposed, thereby realizing fast actuation, and the actuation method of the multilayer laminated piezoelectric actuator greatly improves the actuation speed and actuation displacement of the multilayer laminated piezoelectric actuator. 2. A time-sharing sequentially driving multilayer laminated piezoelectric ceramic driver fast actuation method according to claim 1, characterized in that: the multilayer laminated piezoelectric driver (1) with a specific structure consists of several It is composed of laminated piezoelectric ceramic sheets, each ceramic sheet is plated with electrodes on the upper and lower end surfaces along the lamination direction; each ceramic sheet is connected to the same phase end surface after polarization treatment, forming a structural series connection and an electrical parallel connection. 3. A time-sharing sequentially driving multilayer laminated piezoelectric ceramic driver fast actuation method according to claim 1, characterized in that: the timing control module (2) consists of N steady-state triggers and frequency division N steady-state flip-flops are connected sequentially, the output terminal Q of the previous flip-flop is connected to the input terminal D of the next flip-flop, and the input of the first flip-flop is connected to high level; the clock signal of the steady-state flip-flop CLK is a high-frequency square wave with frequency f input by the signal source, and the 1-setting terminal S of the steady-state flip-flop is uniformly connected to a low level. According to the characteristics of the flip-flop, the output terminals Q ₀ ~ Q _N of N flip-flops form a The shifter, the time difference between each two sequences is controlled by a clock signal with a value of 1/f seconds. 4. A time-sharing sequentially driving multilayer laminated piezoelectric ceramic driver fast actuation method according to claim 3, characterized in that: the high-frequency square wave signal with a frequency of f in the timing control module (2) After the frequency division by the frequency divider, the frequency is f/2 ⁿ low-frequency signal, which is used to control the 0 terminal R of all flip-flops, which determines the frequency of the control signal. 5. A time-sharing sequentially driving multilayer laminated piezoelectric ceramic driver fast actuation method according to claim 3, characterized in that: the N fast switches in the fast switches (4) are MOS tubes, and can also be Fast electronic switching devices with comparable performance are used.