Radial composite reinforced high-power piezoelectric transformer

Abstract

The invention belongs to the technical field of piezoelectric material devices, and discloses a radial composite reinforced high-power piezoelectric transformer, which comprises a plurality of inner rings, outer rings and metal circular rings which are compounded from inside to outside along the radial direction, the plurality of inner rings are stacked along the axial direction and are connected in parallel, conducting strips are arranged among the plurality of inner rings, and the metal circular rings are arranged on the outer rings. Input electrodes are arranged on the upper surfaces and the lower surfaces of the inner rings, output electrodes are arranged on the upper surfaces of the outer rings, and grounding electrodes are arranged on the lower surfaces of the outer rings and the conducting strips. Input voltage is effectively reduced through the multiple inner rings arranged in parallel, low-voltage driving is achieved, higher voltage gain is further achieved, the overall structural strength is enhanced through the metal circular rings arranged on the outer side, the piezoelectric ceramic is effectively prevented from being broken due to violent vibration in a high-power state, and the piezoelectric ceramic is effectively prevented from being damaged. And the high-power working condition of the transformer is met.

Description

Technical Field

[0001] The invention belongs to the technical field of piezoelectric material devices, and in particular relates to a radial composite reinforced high-power piezoelectric transformer. Background Art

[0002] Piezoelectric transformers are an energy conversion device based on the piezoelectric effect. With the increasing demand for energy conversion efficiency and equipment miniaturization, piezoelectric transformers have gradually become an ideal choice for high-power applications due to their small size, high efficiency, and no electromagnetic interference. Transformers with different structural specifications are designed according to different application scenarios, so that they can be widely used in wireless charging, high-frequency switching power supplies, aerospace, medical equipment, military equipment and other application scenarios. In the medical field, piezoelectric transformers can be used in medical implants such as pacemakers. Due to their energy efficiency, small size, and no electromagnetic interference, they are suitable for micro medical devices. In the aerospace field, due to its high efficiency and lightweight characteristics, it is suitable for power management systems on aerospace vehicles. It can be used in satellites, small drones and other equipment to provide stable power.

[0003] The radial composite piezoelectric transformer in the piezoelectric transformer is a device that uses the vibration of piezoelectric materials in the radial direction to achieve voltage conversion. The existing radial composite piezoelectric transformer only has a single ceramic ring input terminal, and the required input voltage is relatively high. In addition, the overall structural strength is insufficient. When working at high power, the piezoelectric ceramic is prone to cracking due to severe vibration. Summary of the invention

[0004] The purpose of the present invention is to provide a radial composite reinforced high-power piezoelectric transformer to solve the problems that the existing radial composite piezoelectric transformer requires a higher input voltage drive and has a lower voltage gain.

[0005] The technical solution adopted by the present invention is a radially composite reinforced high-power piezoelectric transformer, including multiple inner rings, outer rings and metal rings that are radially composited from the inside to the outside, the multiple inner rings are stacked along the axial direction and connected in parallel with each other, conductive sheets are arranged between the multiple inner rings, the upper surfaces and lower surfaces of the multiple inner rings are provided with input electrodes, the upper surface of the outer ring is provided with an output electrode, and the lower surface of the outer ring and the conductive sheet are provided with grounding electrodes.

[0006] Preferably, the axial heights of the plurality of inner rings, outer rings and metal rings are equal.

[0007] Preferably, the axial heights of the plurality of inner rings, outer rings and metal rings are all less than one fifth of the outer diameter of the metal ring.

[0008] Preferably, the inner ring is made of an emissive piezoelectric ceramic material, and the outer ring is made of a soft piezoelectric ceramic material.

[0009] Preferably, the material of the metal ring is any one of aluminum alloy, aluminum-magnesium alloy, titanium alloy and copper.

[0010] Preferably, the inner ring, the outer ring and the metal ring are bonded together by epoxy resin glue.

[0011] Preferably, the conductive sheet is a copper sheet.

[0012] Preferably, the upper and lower surfaces of the inner and outer rings are plated with silver electrodes.

[0013] Preferably, the inner ring is an axially polarized piezoelectric ceramic ring or a radially polarized piezoelectric ceramic ring.

[0014] Preferably, the outer ring is an axially polarized piezoelectric ceramic ring or a radially polarized piezoelectric ceramic ring.

[0015] The beneficial effects of the present invention are: The present invention is provided with a plurality of inner rings stacked along the axial direction, and the inner rings are connected in parallel, which effectively reduces the input voltage, realizes low-voltage driving, and further realizes a higher voltage gain.

[0016] The present invention can change the resonance frequency, voltage gain and power efficiency of the piezoelectric ceramic transformer by changing the geometrical dimensions of the inner ring, the outer ring and the metal ring.

[0017] The present invention is provided with a metal ring on the outermost side, which enhances the overall structural strength and effectively prevents the piezoelectric ceramic from being broken due to severe vibration under high-power conditions, thereby meeting the high-power working conditions of the transformer.

[0018] The outermost metal ring of the present invention can improve heat dissipation and prevent the adverse effects of excessive temperature on the piezoelectric ceramics, thereby meeting the conditions for high-power operation of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a cross-sectional view of the radial composite reinforced high-power piezoelectric transformer of the present invention.

[0020] Figure 2 It is a three-dimensional diagram of the radial composite reinforced high-power piezoelectric transformer of the present invention.

[0021] Figure 3 It is a partial enlarged view of the radial composite reinforced high-power piezoelectric transformer of the present invention.

[0022] Figure 4 It is the wiring diagram of the present invention.

[0023] Figure 5 It is the equivalent circuit diagram.

[0024] Figure numerals: 1. inner ring; 2. outer ring; 3. metal ring. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1 The radial composite reinforced high-power piezoelectric transformer of the present invention is as follows: Figure 1 , Figure 2 and Figure 3 As shown, it includes multiple inner rings 1, outer rings 2 and metal rings 3 which are compounded radially from the inside to the outside. The multiple inner rings 1 are stacked along the axial direction and connected in parallel with each other. Conductive sheets are arranged between the multiple inner rings 1. Figure 4 As shown, the upper and lower surfaces of each inner ring 1 are provided with input electrodes, the upper surface of the outer ring 2 is provided with an output electrode, and the lower surface of the outer ring 2 and the conductive sheet are provided with grounding electrodes.

[0027] The present invention is provided with a plurality of inner rings stacked along the axial direction, and the inner rings are connected in parallel, thereby realizing multiple inputs of the piezoelectric ceramic transformer, effectively reducing the input voltage, realizing low-voltage drive, and further realizing a higher voltage gain.

[0028] Example 2 Based on Example 1, in this embodiment, the axial heights of multiple inner rings 1, outer rings 2 and metal rings 3 are equal, and the upper end faces and lower end faces are in the same plane, and the axial height is less than one fifth of the outer diameter of the metal ring 3.

[0029] In a specific embodiment, the inner ring 1 and the outer ring 2 are both made of piezoelectric ceramic materials with high mechanical quality factors. The inner ring 1 is a piezoelectric ceramic material with high emissivity, such as PZT-4. The outer ring 2 is a soft piezoelectric material with high piezoelectric coefficient, such as PZT-5.

[0030] In some feasible embodiments, the inner ring 1 may also use other piezoelectric materials, such as PZT-8 and other piezoelectric materials, which require the material to have low dielectric loss and mechanical loss, high electromechanical conversion coefficient, high Curie temperature, and high temperature stability.

[0031] In some feasible embodiments, the outer ring 2 may also be made of soft piezoelectric material, such as PZT-5 series or relaxor ferroelectric single crystal.

[0032] Optionally, the inner ring 1 and the outer ring 2 can both use axially polarized piezoelectric ceramic rings, or both use radially polarized piezoelectric ceramic rings, or the inner ring 1 is a radially polarized piezoelectric ceramic ring and the outer ring 2 is an axially polarized piezoelectric ceramic ring, or the inner ring 1 is an axially polarized piezoelectric ceramic ring and the outer ring 2 is a radially polarized piezoelectric ceramic ring.

[0033] Optionally, the material of the metal ring 3 is any one of aluminum alloy, aluminum-magnesium alloy, titanium alloy and copper. The material is required to have good elasticity, low loss, good vibration transmission performance and strong heat transfer performance to increase the heat dissipation performance of the transformer.

[0034] In a specific embodiment, the inner ring 1, the outer ring 2 and the metal ring 3 are bonded together by epoxy resin glue.

[0035] In some feasible embodiments, the dimensions of the inner ring 1 , the outer ring 2 and the metal ring 3 are strictly controlled, and the components are tightly combined by taking advantage of the thermal expansion and contraction characteristics of different materials.

[0036] In a specific embodiment, the conductive sheet is a copper sheet.

[0037] In a specific embodiment, the upper and lower surfaces of the plurality of inner rings 1 and outer rings 2 are plated with silver electrodes.

[0038] Example 3 Based on Example 1 or Example 2, this example provides the working principle of the radial composite reinforced high-power piezoelectric transformer of the present invention.

[0039] (1) Electrical-mechanical energy conversion at the input end: The upper and lower surfaces of the inner ring 1 of the piezoelectric transformer receive electrical signals (usually AC voltage), and mechanical vibrations are generated at the input end due to the inverse piezoelectric effect of the piezoelectric material. That is, when a voltage is applied to the input end of the inner ring 1, the lattice structure of the piezoelectric material is deformed and vibrations are generated.

[0040] (2) Mechanical-electrical energy conversion at the output end: When the mechanical vibration is transmitted to the output end, the piezoelectric material converts the mechanical vibration into an electrical signal again through the positive piezoelectric effect. At the output end of the outer ring 2, the strain caused by the mechanical vibration will cause the piezoelectric material to generate an electric charge, thereby outputting an AC voltage at the output end of the outer ring 2.

[0041] (3) Operating frequency The piezoelectric transformer should be operated at the resonant frequency to achieve maximum voltage gain.

[0042] Example 4 In the above embodiment, an alternating voltage V is applied by an electrical signal i When the inner ring 1 is excited, the inner ring 1 generates mechanical vibration due to the inverse piezoelectric effect of the piezoelectric material. That is, when a voltage is applied to the inner ring 1, the lattice structure of the piezoelectric material is deformed, generating vibration.

[0043] When the driving voltage frequency of the piezoelectric ceramic transformer is equal to the resonant frequency of the piezoelectric ceramic transformer, the mechanical vibration of the transformer reaches its maximum. At this time, the voltage gain and efficiency of the transformer are both maximized. The piezoelectric ceramic transformer should operate at its resonant frequency.

[0044] When the mechanical vibration is transmitted to the outer ring 2, the piezoelectric material generates a charge through the positive piezoelectric effect, i.e., the strain caused by the mechanical vibration, and converts the mechanical vibration into an electrical signal again. A certain potential distribution is generated in the outer ring 2, so a certain amplitude voltage V appears on its metal electrode. o The frequency of the voltage is equal to the input voltage frequency of the transformer, and the amplitude of the voltage is related to the inner and outer radii of the inner ring 1 and the outer ring 2 and the piezoelectric coefficient of the piezoelectric ceramic material.

[0045] Since the geometric dimensions of each piezoelectric ceramic ring in the piezoelectric ceramic transformer are adjustable, piezoelectric ceramic rings of different sizes will produce different output voltages and voltage gains. Therefore, the piezoelectric ceramic transformer with a stacked structure is to experimentally improve the voltage gain by rationally designing piezoelectric ceramic rings of different sizes. At the same time, by connecting different sizes of resistance loads to the output end, the output voltage can be increased or decreased to achieve the purpose of voltage change.

[0046] Example 5 like Figure 5 The electromechanical equivalent circuit diagram of the present invention is shown in Figure 1. The ceramic ring stack at the inner ring input end and the ceramic ring at the output end are represented by two four-port electromechanical equivalent circuits. With the help of the series-parallel relationship of the impedance and the equivalent circuit diagram, the input impedance Z of the piezoelectric ceramic transformer can be obtained. e : (1) Among them, R1 is the dielectric loss of the piezoelectric ceramic material itself during the operation of the simulated transformer; PN 31 is the electromechanical conversion coefficient of the piezoelectric ceramic ring of the piezoelectric ceramic transformer, and P is the number of stacked rings; j is an imaginary unit, ω=2πf, ω represents the angular frequency, π is the circumference of a circle, and f represents the frequency; PC l is the static capacitance; In formula (1), Z m is the input mechanical impedance of the piezoelectric ceramic transformer, and its specific expression is: (2)

[0047]

[0048]

[0049]

[0050]

[0051]

[0052] Among them, Z m is the input mechanical impedance of the piezoelectric ceramic transformer; Z m1 , Z m2 , Z m3 , Z m4 , Z m5 , Z m6 To derive the intermediate parameters of the process; Z 1p , Z 2p , Z 3p is the equivalent impedance of inner loop 1; R m To simulate the mechanical stress and strain loss caused by the conduction and deformation of mechanical stress at the input and output ends of the piezoelectric transformer during operation; Z 11 , Z 22 , Z 33 is the equivalent impedance of outer loop 2; n 22 , n 11 , n2 are the mechanical conversion coefficients of different piezoelectric ceramic rings; N 31 ' represents the electromechanical conversion coefficient of the piezoelectric ceramic ring of the piezoelectric ceramic transformer; j is an imaginary unit, ω=2πf, ω represents the angular frequency, π is the circumference of a circle, and f represents the frequency; C 0r Represents static capacitance; R L is the load impedance at the output end of the piezoelectric transformer; R2 is the dielectric loss of the piezoelectric ceramic material itself during the operation of the simulated transformer; R n To simulate the energy loss caused by the large difference in elastic modulus between piezoelectric materials and metal materials, contact interface friction, and mechanical wave reflection and absorption; Z 1m , Z 2m , Z 3m is the equivalent impedance of the metal ring 3.

[0053] Based on the above formula, it can be seen that the input impedance of the piezoelectric ceramic transformer is a complex number and is related to the frequency of the electrical signal. When the modulus of the impedance reaches the minimum and maximum values ​​respectively, the resonant frequency and anti-resonant frequency equations of the piezoelectric ceramic transformer can be obtained. The resonant frequency equation is: Abs(Z e ) = minimum (3) Anti-resonance frequency equation: Abs(Z e ) = maximum (4) Voltage gain G v : (5)

[0054]

[0055]

[0056] Where: G v represents the voltage gain; V0 is the output voltage signal, V i is the input voltage signal; PN 31 , N 31 ' represents the electromechanical conversion coefficient of the piezoelectric ceramic ring of the piezoelectric ceramic transformer, and P is the number of stacked rings; Z 1p , Z 2p , Z 3p is the equivalent impedance of inner loop 1; Z 11 , Z 22 , Z 33 is the equivalent impedance of outer loop 2; Z m is the input mechanical impedance of the piezoelectric ceramic transformer; Z n , Z a , Z b , Z m6 To derive the intermediate parameters of the process; n 22 , n 11 , n2 are the mechanical conversion coefficients of different piezoelectric ceramic rings; Z 11 , Z 22 , Z 33 is the equivalent impedance of outer loop 2; R L is the load impedance at the output end of the piezoelectric transformer; R2 is the dielectric loss of the piezoelectric ceramic material itself during the operation of the simulated transformer; j is an imaginary unit, ω=2πf, ω represents the angular frequency, π is the circumference of a circle, and f represents the frequency; C 0r Represents static capacitance; R m To simulate the mechanical stress and strain loss generated by the conduction and deformation of mechanical stress experienced by the input and output ends of the piezoelectric transformer during operation.

[0057] Based on the above analysis and formula, the following piezoelectric ceramic transformer is designed: The radii of the piezoelectric ceramic ring and the metal ring from the inside to the outside are a, b, c, and d respectively. The thickness of a single input ring is h0. P is the number of stacked rings, and the total thickness h=P×h0.

[0058] In this embodiment, a=0.006; b=0.020; c=0.03; d=0.042; h0=0.005; P=2; h=0.01 Load resistance R L =2500 ohms, the inner ring 1 and the outer ring 2 are both made of PZT-4 material, and the material of the metal circle 3 is hard aluminum.

[0059] Using the resonance / anti-resonance frequency equations (3), (4) and the voltage gain formula (5), the operating frequency f of the piezoelectric ceramic composite transformer of this embodiment can be obtained: r and the anti-resonance frequency f a They are: f r =27.9kHz, f a =31.6kHz, the voltage gain ratio is G v =3.2.

[0060] Example 6 The difference from Example 5 is that in this embodiment, a=0.006; b=0.020; c=0.03; d=0.042; h0=0.005; P=2; and h=0.01.

[0061] Load resistance R L =1000 ohms, the piezoelectric ceramic rings are all made of PZT-4 material, and the metal conductive ring 2 is made of hard aluminum.

[0062] Using the resonance / anti-resonance frequency equations (3), (4) and the voltage gain formula (5), the operating frequency f of the piezoelectric ceramic composite transformer of this embodiment can be obtained: r and the anti-resonance frequency f a They are: f r =27.7kHz, f a =31.2kHz, the voltage gain ratio is G v =2.1.

[0063] Example 6 The difference from Example 5 is that in this embodiment, a=0.006; b=0.015; c=0.03; d=0.042; h0=0.005; P=2; and h=0.01.

[0064] Load resistance R L =2500 ohms, the piezoelectric ceramic rings are all made of PZT-4 material, and the metal conductive ring 2 is made of hard aluminum.

[0065] Using the resonance / anti-resonance frequency equations (3), (4) and the voltage gain formula (5), the operating frequency f of the piezoelectric ceramic composite transformer of this embodiment can be obtained: r and the anti-resonance frequency f a They are: f r =28.7kHz, f a =31.6kHz, the voltage gain ratio is G v =1.6.

[0066] Example 7 The difference from Example 5 is that, in this embodiment, a=0.006; b=0.025; c=0.03; d=0.042; h0=0.005; P=2; and h=0.01.

[0067] Load resistance R L =2500 ohms, the piezoelectric ceramic rings are all made of PZT-4 material, and the metal conductive ring 2 is made of hard aluminum.

[0068] Using the resonance / anti-resonance frequency equations (3) and (4) and the voltage gain formula (5), it can be concluded that the operating frequency fr and the anti-resonance frequency fa of the piezoelectric ceramic composite transformer of this embodiment are: fr = 27.9 kHz, fa = 32.5 kHz, and the voltage gain ratio is Gv = 4.8.

[0069] Example 8 The difference from Example 5 is that in this embodiment, a=0.006; b=0.025; c=0.035; d=0.042; h0=0.005; P=2; and h=0.01.

[0070] Load resistance R L =2500 ohms, the inner ring 1 and the outer ring 2 are both made of PZT-4 material, and the metal conductive ring 2 is made of hard aluminum.

[0071] Using the resonance / anti-resonance frequency equations (3), (4) and the voltage gain formula (5), the operating frequency f of the piezoelectric ceramic composite transformer of this embodiment can be obtained: rand the anti-resonance frequency f a They are: f r =25.4kHz, f a =29.8kHz, the voltage gain ratio is G v =5.2.

[0072] Example 9 The difference from Example 5 is that, in this embodiment, a=0.006; b=0.020; c=0.03; d=0.042; h0=0.0025; P=4; and h=0.01.

[0073] Load resistance R L =2500 ohms, the piezoelectric ceramic rings are all made of PZT-4 material, and the metal conductive ring 2 is made of hard aluminum.

[0074] Using the resonance / anti-resonance frequency equations (3), (4) and the voltage gain formula (5), the operating frequency f of the piezoelectric ceramic composite transformer of this embodiment can be obtained: r and the anti-resonance frequency f a They are: f r =25.7kHz, f a =30.1kHz, the voltage gain ratio is G v =3.6.

[0075] Components and structures not described in detail in the embodiments are well-known components and common structures or common means in the industry and are not described one by one here.

Claims

1. A radial composite reinforced high-power piezoelectric transformer, characterized in that: The invention comprises a plurality of inner rings (1), an outer ring (2) and a metal ring (3) which are compounded radially from the inside to the outside, wherein the plurality of inner rings (1) are stacked in an axial direction and connected in parallel with each other, a conductive sheet is arranged between the plurality of inner rings (1), the upper surfaces and lower surfaces of the plurality of inner rings (1) are both provided with input electrodes, the upper surface of the outer ring (2) is provided with an output electrode, and the lower surface of the outer ring (2) and the conductive sheet are both provided with a grounding electrode.

2. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The axial heights of the plurality of inner rings (1), the outer ring (2) and the metal ring (3) are equal.

3. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The axial heights of the plurality of inner rings (1), the outer ring (2) and the metal ring (3) are all less than one fifth of the outer diameter of the metal ring (3).

4. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The inner ring (1) is made of an emission-type piezoelectric ceramic material, and the outer ring (2) is made of a soft piezoelectric ceramic material.

5. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The material of the metal ring (3) is any one of aluminum alloy, aluminum-magnesium alloy, titanium alloy and copper.

6. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The inner ring (1), the outer ring (2) and the metal ring (3) are bonded together by epoxy resin glue.

7. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The conductive sheet is a copper sheet.

8. The radial composite reinforced high-power piezoelectric transformer according to claim 1, characterized in that: The upper and lower surfaces of the inner ring (1) and the outer ring (2) are plated with silver electrodes.

9. The radial composite reinforced high-power piezoelectric transformer according to any one of claims 1 to 8, characterized in that: The inner ring (1) is an axially polarized piezoelectric ceramic ring or a radially polarized piezoelectric ceramic ring.

10. The radial composite reinforced high-power piezoelectric transformer according to any one of claims 1 to 8, characterized in that: The outer ring (2) is an axially polarized piezoelectric ceramic ring or a radially polarized piezoelectric ceramic ring.

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