Design method of vehicle vibration energy collection system

Abstract

The invention provides a design method of a vehicle vibration energy collection system. Obtaining a frequency change range of vibration excitation and arranging a phononic crystal plate, wherein the phononic crystal plate comprises a vibration reduction phononic crystal and an energy collection phononic crystal; according to the frequency change range, materials and geometric parameters of all structures in the photonic crystal plate; determining a shunt circuit and a parallel synchronous switch circuit of the vibration energy collection photonic crystal; correspondingly determining a capacitance extreme value and a capacitance value range of an external capacitor in the shunt circuit according to the upper limit and the lower limit of the frequency change range; the current excitation frequency is determined based on the value of the external capacitor, and the direct current output voltage corresponding to the parallel synchronous switch circuit under the current excitation frequency is calculated according to the Kirchhoff's current law, so that energy generated when the vehicle vibrates is collected through the rectification capacitor of the parallel synchronous switch circuit. According to the design method of the vehicle vibration energy collection system, the working frequency band is wide, and the energy collection utilization rate is high.

Description

Technical Field

[0001] The invention relates to the technical field of phononic crystal plate design, and in particular to a design method for a vehicle vibration energy collection system. Background Art

[0002] When a vehicle is driving, its components will generate strong vibrations within a certain frequency range. Currently, phononic crystals are mainly used to analyze and collect the vibration energy generated by these components during driving. Phononic crystals have attracted widespread attention due to their superiority in controlling the propagation of elastic waves. They are used in vibration reduction and noise reduction, waveguides, energy collection, etc., and have broad application prospects in the fields of construction, aerospace, navigation, and automobiles.

[0003] The currently widely used method of energy collection with the help of phononic crystals is mainly to attach the energy collection device to the surface of the vibrating plate, and convert, collect and store the vibration energy into electrical energy through the energy collection device. However, the energy collection efficiency of the existing attached energy collection device is closely related to the resonant frequency of the energy collection system itself, and can only collect energy at a single vibration frequency. In actual applications, the working frequency band is narrow and the energy collection utilization rate is not high. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a design method for a vehicle vibration energy harvesting system to solve the technical problems existing in the prior art.

[0005] The present invention provides a design method for a vehicle vibration energy harvesting system, comprising: Obtaining a frequency variation range of vibration excitation of a part on a vehicle, and arranging a phononic crystal plate on the part, wherein the phononic crystal plate includes a plurality of rows of vibration-damping phononic crystals and at least one row of vibration energy-collecting phononic crystals arranged in the plurality of rows of vibration-damping phononic crystals; Determine the materials and geometric parameters of the substrate of the phononic crystal plate, the vibration-damping phononic crystal, and the piezoelectric sheet and cantilever beam in the vibration energy collection phononic crystal according to the frequency variation range; Determine the collection efficiency of vibration energy based on the design requirements, and determine the shunt circuit for collecting the natural frequency of the phononic crystal and the parallel synchronous switch circuit for collecting the vibration energy based on the collection efficiency; Determine the capacitance extreme value of the external capacitor in the shunt circuit according to the upper limit and the lower limit of the frequency variation range, and determine the capacitance value range of the external capacitor in the shunt circuit according to the capacitance extreme value; Determine the current excitation frequency of a part on the vehicle, calculate the DC output voltage corresponding to the parallel synchronous switch circuit at the current excitation frequency according to Kirchhoff's current law, and collect the energy of the vehicle vibration through the rectifier capacitor of the parallel synchronous switch circuit.

[0006] Preferably, the vibration-damping phononic crystal includes a scatterer arranged on the phononic crystal plate and an elastic element sleeved on the outside of the scatterer, and the energy-collecting phononic crystal includes a plurality of support blocks arranged at intervals, a cantilever beam is arranged between the support blocks, one end of the cantilever beam is connected to the support block, and the other end of the cantilever beam is suspended, and piezoelectric sheets are arranged at both ends of the cantilever beam.

[0007] Preferably, the step of determining the materials and geometric parameters of the substrate of the phononic crystal plate, the vibration-damping phononic crystal, the piezoelectric sheet and the cantilever beam in the vibration energy collection phononic crystal according to the frequency variation range comprises: Obtain the frequency variation range of vibration excitation of a certain part on the vehicle, and determine the band gap variation range according to the frequency variation range of vibration excitation; Determine the base material and lattice constant of the phononic crystal plate, the material and radius of the elastic element, and the material, radius and thickness of the scatterer according to the band gap variation range; The materials and geometric parameters of the supporting block, cantilever beam and piezoelectric piece in the vibration energy harvesting phononic crystal are determined according to the band gap variation range.

[0008] Preferably, the step of determining the shunt circuit for collecting the natural frequency of the vibration energy collecting phononic crystal and the parallel synchronous switch circuit for collecting the vibration energy based on the collection efficiency comprises: The piezoelectric sheets at both ends of the cantilever beam are respectively referred to as a first piezoelectric sheet and a second piezoelectric sheet, and the end surfaces of the first piezoelectric sheet and the second piezoelectric sheet away from the cantilever beam are electrically connected; An inductor and a resistor are connected in series on the end surface of the first piezoelectric sheet away from the cantilever beam and the side surface of the cantilever beam, and then connected in parallel with an external capacitor to form the shunt circuit; Select four diodes to form a rectifier bridge, and the four diodes are respectively recorded as D1, D2, D3, and D4; Two MOS tubes are connected in parallel between line D1D2 and line D3D4, and a rectifier capacitor is connected in parallel between line D2D4 and line D1D3 to form the parallel synchronous switch circuit, which is connected to both ends of the first piezoelectric sheet.

[0009] Preferably, the expression of the capacitance extreme value is:

[0010] In the formula, The lower limit of the frequency variation range The capacitance extreme value corresponding to the external capacitor, The upper limit of the frequency variation range The capacitance extreme value corresponding to the external capacitor, is the lower limit circular frequency; , is the upper limit circular frequency; ;

[0011] In the formula, is the short-circuit compliance coefficient of the piezoelectric film, is the piezoelectric strain constant of the piezoelectric film, is the constant strain dielectric constant of the piezoelectric film, is the density of the piezoelectric sheet, and is the elastic modulus and density of the cantilever beam, and is the cross-sectional area and central section moment of inertia of the cantilever beam, and is the cross-sectional area and central section moment of inertia of the piezoelectric patch, is the cantilever beam length.

[0012] Preferably, the expression of the DC output voltage is:

[0013] is the impedance of the parallel synchronous switch circuit, and the expression is:

[0014] In the formula, is the circular frequency of vibration of the piezoelectric cantilever, is the capacitance value of the piezoelectric cantilever with interface circuit, It is the phase difference corresponding to the voltage drop of the piezoelectric film during the electrode reversal process, and the number of electrode reversals corresponds to the current excitation frequency. is the voltage ratio of the piezoelectric film before and after the electrode reversal, is the electromechanical coupling coefficient, is the maximum amplitude at the end of the cantilever beam.

[0015] Preferably, the frequency variation range is 20 Hz-100 Hz.

[0016] The beneficial effects of the present invention compared with the prior art are as follows: the design method of the vehicle vibration energy harvesting system proposed in the present application first obtains the frequency variation range of the vibration excitation of a certain part on the vehicle, and then arranges a phononic crystal plate on the part, the phononic crystal plate including a vibration-damping phononic crystal and an energy-collecting phononic crystal; the materials and structural parameters of the vibration-damping phononic crystal and the energy-collecting phononic crystal in the phononic crystal plate are determined according to the frequency variation range; further, a shunt circuit of the natural frequency and a parallel synchronous switching circuit for collecting vibration energy are arranged on the energy-collecting phononic crystal; the capacitance value range of the external capacitor in the shunt circuit is determined according to the frequency variation range, and the capacitance of the external capacitor is changed within the capacitance value range. By taking the value, the current excitation frequency of a part on the vehicle can be determined; then the DC output voltage of the current excitation frequency of the parallel synchronous switch circuit is calculated, and the vibration energy is recovered through the rectifier capacitor in the parallel synchronous switch circuit, and the voltage of the rectifier capacitor is the DC output voltage; the vehicle vibration energy collection system designed in the application sets a shunt circuit and a parallel synchronous switch circuit on the energy collection phononic crystal, and by changing the value of the external capacitor in the shunt circuit, the energy of the part at different excitation frequencies can be recovered, and the recovered energy is stored through the rectifier capacitor in the parallel synchronous switch circuit; the working frequency band is wide during energy recovery, which greatly improves the energy collection rate and is suitable for large-scale promotion.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of a design method of a vehicle vibration energy harvesting system in an embodiment of the present invention; Figure 2 is a schematic diagram of the bottom plate structure in an embodiment of the present invention; Figure 3 Schematic diagram of the structure of the phononic crystal plate in an embodiment of the present invention; Figure 4 Schematic diagram of the connection structure between the cantilever beam and the piezoelectric sheet in an embodiment of the present invention; Figure 5 Schematic diagram of the structure of a parallel synchronous switch circuit in an embodiment of the present invention; Figure 6 is a vibration energy collection curve diagram in an embodiment of the present invention; Figure 7 Schematic diagram of excitation frequency detection in an embodiment of the present invention.

[0019] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0022] Embodiment 1 See also Figure 1 , which is a design method of a vehicle vibration energy harvesting system provided by the present invention, specifically comprising steps S10 to S50: S10, obtaining a frequency variation range of vibration excitation of a part on a vehicle, and arranging a phononic crystal plate on the part, wherein the phononic crystal plate includes a plurality of rows of vibration-damping phononic crystals and at least one row of vibration energy-collecting phononic crystals arranged in the plurality of rows of vibration-damping phononic crystals; In the specific implementation, a bottom panel of a certain car model is taken as the object, the panel thickness is 2 mm, and the material is steel; the vibration frequency of the bottom panel is 20 Hz ~ 100 Hz; a corresponding vehicle vibration energy collection system is designed, and optionally, in this embodiment, as Figure 2 and Figure 3 As shown, a part of the bottom plate is replaced by a phononic crystal plate, and the phononic crystal plate can be a 7×7 structure, specifically including six columns of vibration-damping phononic crystals and a column of vibration energy-collecting phononic crystals arranged in the six columns of vibration-damping phononic crystals; the vibration energy-collecting phononic crystals are in the fourth column of the phononic crystal plate.

[0023] Optional, such as Figure 3 As shown, the vibration-damping phononic crystal includes a scatterer arranged on the phononic crystal plate and an elastic element sleeved on the outside of the scatterer, the elastic element is in a circular ring shape and can be used to transfer the vibration of the plate to the scatterer, and the scatterer is cylindrical and is used to absorb vibration; the energy-collecting phononic crystal includes a plurality of support blocks arranged at intervals, a cantilever beam is arranged between the support blocks, one end of the cantilever beam is connected to the support block, and the other end of the cantilever beam is suspended, and piezoelectric sheets are arranged at both ends of the cantilever beam.

[0024] S20, determining the materials and geometric parameters of the substrate of the phononic crystal plate, the vibration-damping phononic crystal, the piezoelectric sheet and the cantilever beam in the vibration energy collection phononic crystal according to the frequency variation range; Optionally, the step of determining the materials and geometric parameters of the substrate of the phononic crystal plate, the vibration-damping phononic crystal, and the piezoelectric sheet and cantilever beam in the vibration energy collection phononic crystal according to the frequency variation range includes: Obtain the frequency variation range of vibration excitation of a certain part on the vehicle, and determine the band gap variation range according to the frequency variation range of vibration excitation; Determine the base material and lattice constant of the phononic crystal plate, the material and radius of the elastic element, and the material, radius and thickness of the scatterer according to the band gap variation range; The materials and geometric parameters of the supporting block, cantilever beam and piezoelectric piece in the vibration energy harvesting phononic crystal are determined according to the band gap variation range.

[0025] Optionally, the band gap variation range is the same as the frequency variation of the vibration excitation, both of which are 20Hz~100Hz. The original thickness of the bottom panel of the car is 2mm, and the original material is steel. When the additional mass of the phononic crystal plate is not too large, the matrix material should be a material with a small density. Therefore, in this embodiment, the matrix material of the phononic crystal plate is designed to be plexiglass, replacing the steel material at the vibration concentration point of the bottom panel of the car, and keeping the thickness unchanged. The elastic element material can be silicone, and the scatterer can be a lead column.

[0026] The structure of the vibration energy harvesting phononic crystal is a sandwich cantilever beam structure with a support block, and the support block and cantilever beam are made of plexiglass; the piezoelectric sheet material should be selected from piezoelectric materials with high short-circuit compliance coefficient, high constant stress dielectric constant, and high voltage electric strain constant. Optionally, the piezoelectric sheet material is PZT-5H; Optionally, the lattice constant of the vibration-damping phononic crystal needs to ensure that the target vibration-damping frequency is within the band gap range, and only a local resonance band gap exists, and no Bragg band gap appears; the thickness of the base beam and piezoelectric sheet of the cantilever beam phononic crystal for vibration energy recovery should be as small as possible; the selection of the width of the base beam and the piezoelectric sheet needs to ensure that the additional mass is not too large; the material parameters of each structure are shown in Table 1, and the geometric parameters are shown in Table 2; Table 1 Material parameters

[0027] Table 2 Geometric parameters

[0028] S30, determining the collection efficiency of vibration energy based on the design requirements, and determining a shunt circuit for collecting the natural frequency of the phononic crystal and a parallel synchronous switch circuit for collecting the vibration energy based on the collection efficiency; The collection efficiency of vibration energy can be determined based on the actual situation such as the location and structure of the parts.

[0029] Optionally, the step of determining a shunt circuit for collecting the natural frequency of the vibration energy collecting phononic crystal and a parallel synchronous switch circuit for collecting the vibration energy based on the collection efficiency includes: The piezoelectric sheets at both ends of the cantilever beam are respectively referred to as a first piezoelectric sheet and a second piezoelectric sheet, and the end surfaces of the first piezoelectric sheet and the second piezoelectric sheet away from the cantilever beam are electrically connected; An inductor and a resistor are connected in series on the end surface of the first piezoelectric sheet away from the cantilever beam and the side surface of the cantilever beam, and then connected in parallel with an external capacitor to form the shunt circuit; Select four diodes to form a rectifier bridge, and the four diodes are respectively recorded as D1, D2, D3, and D4; Two MOS tubes are connected in parallel between line D1D2 and line D3D4, and a rectifier capacitor is connected in parallel between line D2D4 and line D1D3 to form the parallel synchronous switch circuit, which is connected to both ends of the first piezoelectric sheet.

[0030] Indicatively, Figure 4 As shown, the piezoelectric sheets at the upper and lower ends of the cantilever beam are respectively recorded as the first piezoelectric sheet and the second piezoelectric sheet. The upper surface of the upper piezoelectric sheet is connected to the lower surface of the lower piezoelectric sheet on the left side of the cantilever beam through a wire, and the lower surface of the upper piezoelectric sheet is connected to the upper surface of the lower piezoelectric sheet to ensure that the two piezoelectric sheets have the same polarization direction. An external inductor L and a resistor R are connected in series between the upper surface of the upper piezoelectric sheet on the right side of the cantilever beam and the central cantilever beam, and then connected in parallel with an external capacitor C to obtain a shunt circuit for collecting the natural frequency of the phononic crystal for vibration energy collection.

[0031] Indicatively, Figure 5 As shown, after four diodes are respectively used to form a rectifier bridge, the four diodes are respectively recorded as D1, D2, D3, and D4, and the diode model is 1BH62. Two MOS tubes and a rectifier capacitor are connected in parallel in the middle of the rectifier bridge. The two MOS tubes are recorded as Q1 and Q2, and the MOS tube model is 2N6659. The rectifier capacitor is Cs1, and the rectifier capacitor Cs1 can be used to collect vibration energy, and R3 can be regarded as a load; a parallel synchronous switch circuit is formed, and the upper and lower joints on the left side of the parallel synchronous switch circuit are respectively connected to the upper and lower surfaces of the upper piezoelectric sheet of the cantilever beam.

[0032] S40, determining the capacitance extreme value of the external capacitor in the shunt circuit according to the upper limit and the lower limit of the frequency variation range, and determining the capacitance value range of the external capacitor in the shunt circuit according to the capacitance extreme value; Optionally, the expression of the capacitance extreme value is:

[0033] In the formula, The lower limit of the frequency variation range The capacitance extreme value corresponding to the external capacitor, The upper limit of the frequency variation range The capacitance extreme value corresponding to the external capacitor, is the lower limit circular frequency; , is the upper limit circular frequency; ;

[0034] In the formula, is the short-circuit compliance coefficient of the piezoelectric film, is the piezoelectric strain constant of the piezoelectric film, is the constant strain dielectric constant of the piezoelectric film, is the density of the piezoelectric sheet, and is the elastic modulus and density of the cantilever beam, and is the cross-sectional area and central section moment of inertia of the cantilever beam, and is the cross-sectional area and central section moment of inertia of the piezoelectric patch, is the cantilever beam length.

[0035] In an embodiment, , according to the materials selected for each structure and the corresponding geometric parameters, we finally get ; The upper limit and lower limit of the external capacitor are not infinite and infinitesimal; in this embodiment, considering the feasibility of practical engineering applications and the convenience of adjustment, the upper limit and lower limit of the external capacitor in the shunt circuit are set to -2 and 2 respectively; to ensure that the natural frequency of the piezoelectric cantilever beam structure can be arbitrarily adjusted within the required range of variation; that is, in this application, the capacitance value range of the external capacitor is: .

[0036] S50, determining the current excitation frequency of a part on the vehicle, and calculating the DC output voltage corresponding to the parallel synchronous switch circuit at the current excitation frequency according to Kirchhoff's current law, so as to collect the energy of the vehicle vibration through the rectifier capacitor of the parallel synchronous switch circuit.

[0037] In specific implementation, the capacitance value range of the external capacitor is By changing the capacitance of the external capacitor, the energy harvesting system can determine the peak harvesting frequency , peak collection frequency To determine the excitation frequency of the automotive parts that can be collected under the capacitance value of the external capacitor; schematically, a finite element model of 7×7 cells is constructed for simulation, such as Figure 6As shown, the vibration energy harvesting system of the present application is arranged on the bottom panel of the automobile, and the vibration transmission loss curve of the bottom panel of the automobile in the range of 20 Hz to 100 Hz is obtained, the horizontal axis is the frequency, and the vertical axis is the vibration attenuation rate; it can be seen that when the vibration frequency is within the range of 20 Hz to 100 Hz, most of the values ​​of the vibration attenuation rate are below -20 dB, and the vibration-damping phononic crystal plate can well suppress the transmission of the vibration on the bottom panel to the nearby panels, and the vibration is confined in the phononic crystal plate, and propagates and is collected along the vibration energy harvesting phononic crystal.

[0038] The vibration energy collection curves when the capacitance values ​​of the external capacitors are set to -1.5719, -0.8257, and -0.3476, respectively. Figure 7 It can be seen that when the capacitance values ​​of the external capacitors are set to -1.5719, the system can collect energy with an excitation frequency of 72Hz for automotive parts; when the capacitance values ​​of the external capacitors are set to -0.8257, the system can collect energy with an excitation frequency of 75Hz for automotive parts; when the capacitance values ​​of the external capacitors are set to -0.3476, the system can collect energy with an excitation frequency of 78Hz for automotive parts; the peak voltage can be calculated based on Kirchhoff's current law, and the peak voltage is the DC output voltage corresponding to the parallel synchronous switch circuit at the current excitation frequency. Figure 7 It can be seen that In this embodiment, the DC output voltage of the parallel synchronous switch circuit is Figure 5 The rectifier capacitor is the voltage across Cs1.

[0039] Optionally, the expression of the DC output voltage is:

[0040] is the impedance of the parallel synchronous switch circuit, and the expression is:

[0041] In the formula, is the circular frequency of vibration of the piezoelectric cantilever, is the capacitance value of the piezoelectric cantilever with interface circuit, It is the phase difference corresponding to the voltage drop of the piezoelectric film during the electrode reversal process, and the number of electrode reversals corresponds to the current excitation frequency. is the voltage ratio of the piezoelectric film before and after the electrode reversal, is the electromechanical coupling coefficient, is the maximum amplitude at the end of the cantilever beam.

[0042] In summary, the design method of the vehicle vibration energy harvesting system proposed in the present application first obtains the frequency variation range of the vibration excitation of a certain part on the vehicle, and then arranges a phononic crystal plate on the part, wherein the phononic crystal plate includes a vibration-damping phononic crystal and an energy-collecting phononic crystal; the material and structural parameters of the vibration-damping phononic crystal and the energy-collecting phononic crystal in the phononic crystal plate are determined according to the frequency variation range; further, a shunt circuit of the natural frequency and a parallel synchronous switching circuit for collecting vibration energy are set on the energy-collecting phononic crystal; the capacitance value range of the external capacitor in the shunt circuit is determined according to the frequency variation range, and the capacitance value range can be determined by changing the value of the external capacitor within the capacitance value range. The current excitation frequency of a part on the vehicle; then calculate the DC output voltage of the current excitation frequency of the parallel synchronous switch circuit, and recover the vibration energy through the rectifier capacitor in the parallel synchronous switch circuit, and the voltage of the rectifier capacitor is the DC output voltage; the vehicle vibration energy collection system designed in the present application sets a shunt circuit and a parallel synchronous switch circuit on the energy collection phononic crystal, and by changing the value of the external capacitor in the shunt circuit, the energy of the part at different excitation frequencies can be recovered, and the recovered energy is stored by the rectifier capacitor in the parallel synchronous switch circuit; the working frequency band is wide during energy recovery, which greatly improves the energy collection rate and is suitable for large-scale promotion.

[0043] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A design method for a vehicle vibration energy harvesting system, characterized in that: include; Obtaining a frequency variation range of vibration excitation of a part on a vehicle, and arranging a phononic crystal plate on the part, wherein the phononic crystal plate includes a plurality of rows of vibration-damping phononic crystals and at least one row of vibration energy-collecting phononic crystals arranged in the plurality of rows of vibration-damping phononic crystals; Determine the materials and geometric parameters of the substrate of the phononic crystal plate, the vibration-damping phononic crystal, and the piezoelectric sheet and cantilever beam in the vibration energy collection phononic crystal according to the frequency variation range; Determine the collection efficiency of vibration energy based on the design requirements, and determine the shunt circuit for collecting the natural frequency of the phononic crystal and the parallel synchronous switch circuit for collecting the vibration energy based on the collection efficiency; Determine the capacitance extreme value of the external capacitor in the shunt circuit according to the upper limit and the lower limit of the frequency variation range, and determine the capacitance value range of the external capacitor in the shunt circuit according to the capacitance extreme value; Determine the current excitation frequency of a part on the vehicle, calculate the DC output voltage corresponding to the parallel synchronous switch circuit at the current excitation frequency according to Kirchhoff's current law, and collect the energy of the vehicle vibration through the rectifier capacitor of the parallel synchronous switch circuit.

2. The design method of the vehicle vibration energy harvesting system according to claim 1, characterized in that: The vibration-damping phononic crystal includes a scatterer arranged on the phononic crystal plate and an elastic element sleeved on the outside of the scatterer. The energy-collecting phononic crystal includes a plurality of support blocks arranged at intervals, a cantilever beam is arranged between the support blocks, one end of the cantilever beam is connected to the support block, and the other end of the cantilever beam is suspended in the air, and piezoelectric sheets are arranged at both ends of the cantilever beam.

3. The design method of the vehicle vibration energy harvesting system according to claim 2, characterized in that: The step of determining the materials and geometric parameters of the substrate of the phononic crystal plate, the vibration-damping phononic crystal, and the piezoelectric sheet and cantilever beam in the vibration energy collection phononic crystal according to the frequency variation range comprises: Obtain the frequency variation range of vibration excitation of a certain part on the vehicle, and determine the band gap variation range according to the frequency variation range of vibration excitation; Determine the base material and lattice constant of the phononic crystal plate, the material and radius of the elastic element, and the material, radius and thickness of the scatterer according to the band gap variation range; The materials and geometric parameters of the supporting block, cantilever beam and piezoelectric piece in the vibration energy harvesting phononic crystal are determined according to the band gap variation range.

4. The design method of the vehicle vibration energy harvesting system according to claim 3, characterized in that: The steps of determining the shunt circuit for collecting the natural frequency of the phononic crystal for vibration energy collection and the parallel synchronous switch circuit for collecting the vibration energy based on the collection efficiency include: The piezoelectric sheets at both ends of the cantilever beam are respectively referred to as a first piezoelectric sheet and a second piezoelectric sheet, and the end surfaces of the first piezoelectric sheet and the second piezoelectric sheet away from the cantilever beam are electrically connected; An inductor and a resistor are connected in series on the end surface of the first piezoelectric sheet away from the cantilever beam and the side surface of the cantilever beam, and then connected in parallel with an external capacitor to form the shunt circuit; Select four diodes to form a rectifier bridge, and the four diodes are respectively recorded as D1, D2, D3, and D4; Two MOS tubes are connected in parallel between line D1D2 and line D3D4, and a rectifier capacitor is connected in parallel between line D2D4 and line D1D3 to form the parallel synchronous switch circuit, which is connected to both ends of the first piezoelectric sheet.

5. The design method of the vehicle vibration energy harvesting system according to claim 4, characterized in that: The expression of the capacitance extreme value is: In the formula, The lower limit of the frequency variation range The capacitance extreme value corresponding to the external capacitor, The upper limit of the frequency variation range The capacitance extreme value corresponding to the external capacitor, is the lower limit circular frequency; , is the upper limit circular frequency; ; In the formula, is the short-circuit compliance coefficient of the piezoelectric film, is the piezoelectric strain constant of the piezoelectric film, is the constant strain dielectric constant of the piezoelectric film, is the density of the piezoelectric sheet, and are the elastic modulus and density of the cantilever beam, and is the cross-sectional area and central section moment of inertia of the cantilever beam, and is the cross-sectional area and central section moment of inertia of the piezoelectric patch, is the cantilever beam length.

6. The design method of the vehicle vibration energy harvesting system according to claim 1, characterized in that: The expression of the DC output voltage is: is the impedance of the parallel synchronous switch circuit, and the expression is: In the formula, is the circular frequency of vibration of the piezoelectric cantilever, is the capacitance value of the piezoelectric cantilever with interface circuit, It is the phase difference corresponding to the voltage drop of the piezoelectric film during the electrode reversal process, and the number of electrode reversals corresponds to the current excitation frequency. is the voltage ratio of the piezoelectric film before and after the electrode reversal, is the electromechanical coupling coefficient, is the maximum amplitude at the end of the cantilever beam.

7. The design method of the vehicle vibration energy harvesting system according to claim 1, characterized in that: The frequency variation range is 20 Hz-100 Hz.

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