CN104935207B - Macro-micro-displacement combined piezoelectric ceramic stack actuator - Google Patents

Abstract

The invention discloses a macro-micro-displacement combined piezoelectric ceramic stack actuator, and belongs to the technical field of macro-micro-displacement driving. The actuator aims at solving the problem that the existing displacement driving device adopting a piezoelectric ceramic stack cannot give consideration to large stroke and high-accuracy displacement resolution. A micro piezoelectric ceramic stack and a macro piezoelectric ceramic stack of the actuator are arranged in a stacking manner; the micro piezoelectric ceramic stack is connected with a first driving power supply by a micro piezoelectric ceramic stack anode and a micro piezoelectric ceramic stack cathode; the macro piezoelectric ceramic stack is connected with a second driving power supply by a macro piezoelectric ceramic stack anode and a macro piezoelectric ceramic stack cathode; a large stroke requirement is realized by the macro piezoelectric ceramic stack; a high displacement resolution requirement is realized by the micro piezoelectric ceramic stack; and the ceramic sheet layer number and the maximum driving voltage of the macro piezoelectric ceramic stack and the micro piezoelectric ceramic stack are reasonably designed. According to the actuator, the large stroke of the actuator can be realized, and the high-accuracy displacement resolution of the actuator can be ensured.

Description

Combination of Macro and Micro Displacement Piezoelectric Ceramic Stack Actuator

technical field

The invention relates to a macro-micro displacement combined piezoelectric ceramic stack actuator, which belongs to the technical field of macro-micro displacement driving.

Background technique

Piezoelectric ceramics are widely used in sensing and driving fields, and piezoelectric ceramic stacking is one of the most widely used forms of piezoelectric ceramics. The displacement of a single piezoelectric ceramic is extremely small after applying a voltage, and the piezoelectric ceramic stack achieves a large displacement by stacking many layers of ceramic sheets together. Usually, the stroke of the piezoelectric ceramic stack is between a few to tens of microns. In order to realize such a stroke, the number of layers of stacked ceramic sheets must reach hundreds of layers. The stacked ceramic sheets are connected in parallel when leading to electrodes, and when an external driving voltage is applied, the driving voltage of all the ceramic sheets is the same. Therefore, the displacement resolution achieved by the piezoelectric ceramic stack depends on the resolution of the applied voltage and the number of stacked layers. The higher the voltage resolution, the smaller the minimum displacement that can be resolved by the piezoelectric ceramic stack; the more layers in the stack, the greater the minimum displacement that can be resolved. In order to ensure the stroke requirements of piezoelectric ceramics, the number of stacked layers should not be too small. Therefore, the displacement resolution accuracy of piezoelectric ceramic stacks is usually improved by improving the voltage resolution. When digital computer control is adopted, the accuracy of voltage resolution depends on the accuracy of analog-to-digital conversion and the maximum applied voltage. The accuracy of analog-to-digital conversion is the number of digits converted by DA. Reducing the maximum applied voltage allows resolution of smaller voltages, but also reduces the travel of the piezo stack. Therefore, in the application, the displacement resolution of the piezoelectric ceramic stack is generally improved by improving the precision of the DA conversion and increasing the number of bits of the DA conversion. However, the number of bits of DA conversion cannot be increased without limit. After increasing to a certain extent, such as 16-bit DA conversion, every increase of one bit will pay a huge cost. On the other hand, due to the influence of noise in the actual application environment, when the minimum resolvable voltage is small to a certain extent, such as a few millivolts, the resolution accuracy of the voltage is at the same level as the noise. Noise does not improve voltage accuracy, and noise suppression is quite complex and difficult. Due to the above-mentioned difficulties and contradictions, in the application of the piezoelectric ceramic stack, a compromise has to be made on the travel and displacement resolution accuracy.

With the development of micro-displacement technology, especially the continuous deepening and promotion of high-tech such as medical treatment, biology, and microelectronics, there is an urgent need for micro-displacement driving devices that can achieve large displacements while maintaining high-precision resolution.

Contents of the invention

The purpose of the present invention is to solve the problem that the existing displacement driving device using piezoelectric ceramic stacks cannot take into account both large stroke and high-precision displacement resolution, and provides a macro-micro displacement combined piezoelectric ceramic stack actuator.

The macro-micro-displacement combined piezoelectric ceramic stack actuator of the present invention includes a micro-piezoelectric ceramic stack, a macro piezoelectric ceramic stack, a micro-piezoelectric ceramic stack positive electrode, a macro piezoelectric ceramic stack positive electrode, and a micro-piezoelectric ceramic stack Stacked negative electrodes and macro piezoelectric ceramic stacked negative electrodes,

The micro piezoelectric ceramic stack is stacked with the macro piezoelectric ceramic stack, the micro piezoelectric ceramic stack is connected to the first driving power supply through the micro piezoelectric ceramic stack positive electrode and the micro piezoelectric ceramic stack negative electrode, and the macro piezoelectric ceramic stack is connected to the first driving power supply through the macro piezoelectric ceramic stack The positive electrode of the piezoelectric ceramic stack and the negative electrode of the macro piezoelectric ceramic stack are connected to the second driving power supply;

The number of piezoelectric ceramic sheets in the micro piezoelectric ceramic stack is n ₁ , and the maximum driving voltage of the first driving power supply is V ₁ ; the stroke S ₁ realized by the micro piezoelectric ceramic stack is:

S ₁ =n ₁ d ₃₃ V ₁ ;

In the formula, _d33 is the piezoelectric constant of the piezoelectric ceramic sheet;

The displacement resolution δ ₁ achieved by the micro piezoelectric ceramic stack is:

In the formula, m is the DA conversion digit of the driving voltage;

The number of piezoelectric ceramic sheets in the macro piezoelectric ceramic stack is n ₂ , and the maximum driving voltage of the second driving power supply is V ₂ ; the stroke S ₂ realized by the macro piezoelectric ceramic stack is:

S ₂ =n ₂ d ₃₃ V ₂ ;

The displacement resolution δ ₂ achieved by the macro piezoelectric ceramic stack is:

Make the stroke S ₁ of the micro piezoelectric ceramic stack and the displacement resolution δ ₂ of the macro piezoelectric ceramic stack satisfy the following relationship:

S ₁ ≥ δ ₂ ,

which is:

Set the expected displacement of the actuator as S ^d , then the expected displacement of the macro piezoelectric ceramic stack for:

In the formula Indicates rounding to zero;

Expected Displacement of Micro Piezo Stacks for:

Make Through calculation, the maximum driving voltage is V ₁ and the maximum driving voltage is V ₂ .

All the piezoelectric ceramic sheets are made of piezoelectric ceramic material PZT-554.

The advantages of the present invention: the macro-micro-displacement combined piezoelectric ceramic stack actuator of the present invention can realize ultra-high-resolution micro-displacement under the general AD conversion accuracy, and its micro-piezoelectric ceramic stack and macro-piezoelectric ceramic stack Larger strokes are achieved by stacking hundreds of layers of ceramic sheets together through processes such as bonding. Since the displacement resolution of the piezoelectric ceramic stack actuator is inversely proportional to the maximum driving voltage and the number of stacked layers when the DA conversion accuracy is constant, the present invention achieves a large stroke through the macro piezoelectric ceramic stack, micro pressure The electric ceramic stack realizes ultra-high-precision resolution. By selecting the number of layers of the macro-micro piezoelectric ceramic stack and the maximum applied voltage, the minimum displacement achieved by the macro piezoelectric ceramic stack is not greater than the stroke of the micro piezoelectric ceramic stack, thereby ensuring The displacement resolution of the actuator is the resolution of the stack of micro piezoelectric ceramics, and the stroke of the entire actuator is the sum of the strokes of the stack of macro and micro piezoelectric ceramics, thus ensuring the large stroke of the actuator, It also guarantees its high-precision displacement resolution.

The invention solves the contradiction between common piezoelectric ceramics stacking to achieve large stroke and high displacement resolution. Large stroke requirements are achieved through macro piezoelectric ceramic stacking, high displacement resolution requirements are achieved through micro piezoelectric ceramic stacking, and the number of ceramic sheets and maximum driving voltage of macro and micro piezoelectric ceramic stacking are reasonably designed. It achieves large travel and high displacement resolution without increasing the DA conversion accuracy requirements and noise processing difficulty, reduces the limitations of piezoelectric ceramic stack applications, expands its application range, and reduces costs.

Description of drawings

Fig. 1 is a structural schematic diagram of a macro-micro-displacement combined piezoelectric ceramic stack actuator according to the present invention;

Fig. 2 is a flow chart of the displacement output of the macro-micro-displacement combined piezoelectric ceramic stack actuator of the present invention.

detailed description

Specific Embodiment 1: The present embodiment will be described below in conjunction with FIG. 1 . The macro-micro displacement combined piezoelectric ceramic stack actuator in this embodiment includes a micro piezoelectric ceramic stack 1, a macro piezoelectric ceramic stack 2, and a micro piezoelectric ceramic stack. Ceramic stack positive electrode 3, macro piezoelectric ceramic stack positive electrode 4, micro piezoelectric ceramic stack negative electrode 5 and macro piezoelectric ceramic stack negative electrode 6,

The micro piezoelectric ceramic stack 1 and the macro piezoelectric ceramic stack 2 are stacked, and the micro piezoelectric ceramic stack 1 is connected to the first driving power supply through the micro piezoelectric ceramic stack positive electrode 3 and the micro piezoelectric ceramic stack negative electrode 5. The electric ceramic stack 2 is connected to the second driving power supply through the macro piezoelectric ceramic stack positive electrode 4 and the macro piezoelectric ceramic stack negative electrode 6;

The number of piezoelectric ceramic sheets in the micro piezoelectric ceramic stack 1 is n ₁ , and the maximum driving voltage of the first driving power supply is V ₁ ; the stroke S ₁ realized by the micro piezoelectric ceramic stack 1 is:

S ₁ =n ₁ d ₃₃ V ₁ ;

In the formula, _d33 is the piezoelectric constant of the piezoelectric ceramic sheet;

The displacement resolution δ ₁ achieved by the micro piezoelectric ceramic stack 1 is:

In the formula, m is the DA conversion digit of the driving voltage;

The number of piezoelectric ceramic sheets in the macro piezoelectric ceramic stack 2 is n ₂ , and the maximum driving voltage of the second driving power supply is V ₂ ; the stroke S ₂ realized by the macro piezoelectric ceramic stack 2 is:

S ₂ =n ₂ d ₃₃ V ₂ ;

The displacement resolution δ ₂ achieved by the macro piezoelectric ceramic stack 2 is:

Make the stroke S1 of the micro piezoelectric ceramic stack ₁ and the displacement resolution δ2 of the macro piezoelectric ceramic stack ₂ satisfy the following relationship:

S ₁ ≥ δ ₂ ,

which is:

In this embodiment, according to actual needs, the micro piezoelectric ceramic stack negative electrode 5 and the macro piezoelectric ceramic stack negative electrode 6 can be short-circuited.

Specific Embodiment 2: The present embodiment will be described below in conjunction with FIG. 2 . This embodiment will further describe Embodiment 1. If the desired displacement of the actuator is set as S ^d , then the desired displacement of the macro piezoelectric ceramic stack 2 for:

In the formula Indicates rounding to zero;

Expected Displacement of Micro Piezo Stack 1 for:

Make Through calculation, the maximum driving voltage is V ₁ and the maximum driving voltage is V ₂ .

Make is the condition that is naturally satisfied when the above distribution is adopted, so that That is, the expected displacement does not exceed the stroke.

In this embodiment, the expected displacement of the micro piezoelectric ceramic stack 1 The acquisition method satisfies the travel constraint of the micro piezoelectric ceramic stack 1 . At this time, the displacement resolution δ of the combined macro-micro displacement piezoelectric ceramic stack actuator is the displacement resolution of the micro piezoelectric ceramic stack 1 , ie: δ=δ ₁ .

Embodiment 3: The present embodiment will be described below with reference to FIG. 1 and FIG. 2 . This embodiment will further describe Embodiment 1 or 2. All the piezoelectric ceramic sheets are made of piezoelectric ceramic material PZT-554.

In this embodiment, the DA conversion number m of the driving voltage can be 8, and the piezoelectric constant d ₃₃ of the piezoelectric ceramic material PZT-554 is 810×10 ⁻¹² m/V.

Specific embodiments of the present invention:

Assuming V ₁ =10V, n ₁ =15, S ₁ =121.5nm and δ ₁ =0.48nm are calculated.

V ₂ =150V, n ₂ =255, calculated to obtain S ₂ =30982.5nm, δ ₂ =121.50nm.

The calculated total stroke S of the actuator is: S=31104nm. Since S ₁ ≥ δ ₂ , in order to satisfy the displacement continuity, the displacement resolution of the macro-micro piezoelectric ceramic stack actuator is calculated to be δ=δ ₁ =0.48nm.

In order to illustrate the superiority of the present invention, the common piezoelectric ceramic stack actuator with the same total number of piezoelectric ceramic sheets n=270, DA conversion accuracy m=8 and maximum driving voltage V=150V is used as a comparison, and its stroke and The displacement resolutions are S = 32805 nm and δ = 128.65 nm, respectively. It can be seen from comparative analysis that the present invention obtains a 268-fold increase in displacement resolution at the cost of a displacement loss of 5.2%.

Referring to FIG. 2 , the working mode of the macro-micro-displacement combined piezoelectric ceramic stack actuator of the present invention is illustrated by taking the desired displacement S ^d =27551nm as an example.

Displacement according to expectations formula, calculated to obtain And then calculated to get Then, according to the above-mentioned expected displacement, the maximum driving voltage V ₁ and the maximum driving voltage V ₂ are respectively calculated and obtained. The calculation of the driving voltage depends on the displacement control algorithm, and can be obtained according to a theoretical formula or a curve or formula fitted through experiments. The calculated driving voltage is transformed into an analog signal by DA conversion and applied to the corresponding driving voltage channel, and then applied to the micro piezoelectric ceramic stack 1 and the macro piezoelectric ceramic stack 2 after power amplification, thereby driving the combined macro and micro displacement piezoelectric Ceramic stack actuators achieve the desired displacement.

Claims (2)

1. A macro and micro displacement combined piezoelectric ceramic stack actuator, characterized in that it comprises a micro piezoelectric ceramic stack (1), a macro piezoelectric ceramic stack (2), and a micro piezoelectric ceramic stack positive electrode (3) , a macro piezoelectric ceramic stack positive electrode (4), a micro piezoelectric ceramic stack negative electrode (5) and a macro piezoelectric ceramic stack negative electrode (6), The micro piezoelectric ceramic stack (1) is stacked with the macro piezoelectric ceramic stack (2), and the micro piezoelectric ceramic stack (1) uses the micro piezoelectric ceramic stack positive electrode (3) and the micro piezoelectric ceramic stack negative electrode (5 ) is connected to the first driving power supply, and the macro piezoelectric ceramic stack (2) is connected to the second driving power supply through the macro piezoelectric ceramic stack positive electrode (4) and the macro piezoelectric ceramic stack negative electrode (6); The number of layers of piezoelectric ceramic sheets in the micro piezoelectric ceramic stack (1) is n ₁ , and the maximum driving voltage of the first driving power supply is V ₁ ; the stroke S ₁ realized by the micro piezoelectric ceramic stack (1) is: S ₁ =n ₁ d ₃₃ V ₁ ; In the formula, _d33 is the piezoelectric constant of the piezoelectric ceramic sheet; The displacement resolution δ ₁ achieved by the micro piezoelectric ceramic stack (1) is: ${\mathrm{<span\; class="notranslate">\; \&delta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>$ In the formula, m is the DA conversion digit of the driving voltage; The number of layers of piezoelectric ceramic sheets in the macro piezoelectric ceramic stack (2) is n ₂ , and the maximum driving voltage of the second driving power supply is V ₂ ; the stroke S ₂ realized by the macro piezoelectric ceramic stack (2) is: S ₂ =n ₂ d ₃₃ V ₂ ; The displacement resolution δ ₂ achieved by the macro piezoelectric ceramic stack (2) is: ${\mathrm{<span\; class="notranslate">\; \&delta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 33</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ;</span>$ Make the stroke S1 of the micro piezoelectric ceramic stack ( ₁ ) and the displacement resolution δ2 of the macro piezoelectric ceramic stack ( ₂ ) satisfy the following relationship: S ₁ ≥ δ ₂ , which is: $\frac{{\mathrm{no}}_2{V}_2}{{\mathrm{no}}_1{V}_1}\&le;2^m-1.$ 2. The macro-micro-displacement combined piezoelectric ceramic stack actuator according to claim 1, characterized in that, Set the expected displacement of the actuator as S ^d , then the expected displacement of the macro piezoelectric ceramic stack (2) for: In the formula Indicates rounding to zero; Expected Displacement of Micro Piezoelectric Ceramic Stack(1) for: ${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; S</span>}}^{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; ;</span>$ Make Through calculation, the maximum driving voltage is V ₁ and the maximum driving voltage is V ₂ .