A resonant piezoelectric power generation system and a resonant inductance optimization method thereof

Abstract

The present invention discloses a resonant piezoelectric power generation system, comprising a piezoelectric generator, a resonant inductor L, a bridge rectifier circuit, a self-powered switch circuit and a charge extraction circuit which are electrically connected in series in sequence, and each part is electrically connected in series to form an overall circuit of the resonant piezoelectric power generation system. The automatic control of the system of the present invention is achieved by the self-power supply and automatic closing and opening of the self-powered switch circuit; by adding a resonant inductor L to the overall circuit and optimizing the design of the resonant inductor L, an optimal resonant inductance value can be obtained, which greatly improves the power conversion efficiency of the traditional synchronous charge extraction circuit. The present invention also discloses a resonant inductance optimization method for a resonant piezoelectric power generation system; the optimal resonant inductor used can greatly increase the output voltage of the piezoelectric generator, improve the AC-DC conversion efficiency of the traditional synchronous charge extraction circuit for piezoelectric power generation, achieve efficient vibration piezoelectric power generation, and thus improve the power conversion efficiency of the system.

Description

Technical Field

[0001] The present invention relates to the field of vibration piezoelectric power generation technology, in particular to a resonant piezoelectric power generation system and a resonant inductance optimization method thereof. Background Art

[0002] Among many forms of environmental energy, vibration is ubiquitous in nature, so vibration energy harvesting is currently the most widely studied self-powered technology for low-power electronic devices. Compared with other vibration energy conversion mechanisms such as electromagnetic and electrostatic, piezoelectric power generation has outstanding advantages such as higher force-electric coupling effect and energy density, no electromagnetic interference, and easy miniaturization and integration, and has received extensive attention and application research. However, the piezoelectric generator outputs high-voltage, high-impedance, and low-current alternating current, which cannot directly power the load of low-power electronic devices. It is necessary to place an interface circuit between the piezoelectric generator and the electrical load to convert the alternating current into direct current (AC-DC conversion). In the AC-DC conversion process, its conversion efficiency is closely related to the interface circuit, and it must be optimized.

[0003] The simplest AC-DC conversion circuit is the traditional bridge rectifier interface circuit, but its disadvantage is that the maximum energy can be obtained from the load only when the load impedance and the output impedance of the piezoelectric generator meet the impedance matching, otherwise the electric energy obtained by the load will be sharply reduced. However, in practice, the output impedance of the piezoelectric generator is very high, and the impedance of low-power electronic equipment is often not a constant, so impedance matching is difficult to achieve, resulting in low energy conversion efficiency. In response to the problem of low energy conversion efficiency of the traditional bridge rectifier interface circuit, people have proposed a nonlinear rectifier interface circuit based on synchronous switching, namely the SSHI circuit. Its basic idea is to add a switch and an inductor to the traditional bridge rectifier interface circuit. When the piezoelectric vibrator reaches the maximum amplitude, the piezoelectric material accumulates the most charge. At this time, the switch is closed instantly, so that the parasitic capacitance of the inductor and the piezoelectric material forms an LC oscillation circuit to extract the accumulated charge, thereby improving the AC-DC conversion efficiency. According to the position of the switch, the SSHI circuit is divided into two categories: one is that the switch is placed behind the rectifier bridge, which is called the synchronous charge extraction circuit; the other is that the switch is placed in front of the rectifier bridge, which is called the synchronous switch circuit.

[0004] For example, patent number CN201520926035.8 discloses a nonlinear interface circuit for broadband piezoelectric power generation, the circuit includes four components, namely, an electronic switch circuit, a bridge rectifier circuit, a voltage control circuit, and a DC-DC conversion circuit, and they are electrically connected in sequence; CN201810871127.9 discloses a low-delay self-powered piezoelectric power generation synchronous charge extraction circuit, including five components, namely, a bridge rectifier circuit, a peak detection circuit, a low-delay voltage divider circuit, a self-powered switch circuit, and a charge extraction circuit, and they are electrically connected in sequence. Compared with the synchronous switch circuit, the biggest advantage of the synchronous charge extraction circuit is that its AC-DC conversion efficiency is independent of the load, which effectively solves the impedance matching problem faced by the traditional bridge rectifier interface circuit, but its conversion efficiency is generally lower than that of the synchronous switch circuit.

[0005] For the synchronous charge extraction piezoelectric power generation system, the most critical issue is how to further improve its AC-DC conversion efficiency, and thus improve the system's power conversion efficiency. To this end, it is necessary to design a new resonant piezoelectric power generation system and its resonant inductance optimization method. Summary of the invention

[0006] In view of the technical problem to be solved, the present invention provides a resonant piezoelectric power generation system and a resonant inductor optimization method thereof. A resonant inductor is added to the existing synchronous charge extraction piezoelectric power generation system, and the resonant inductor is optimized and designed, mainly for solving the technical problem of low power conversion efficiency of the existing synchronous charge extraction piezoelectric power generation system.

[0007] In order to solve the above technical problems, the present invention is implemented by the following technical solutions: A resonant piezoelectric power generation system includes a piezoelectric generator, a resonant inductor L, a bridge rectifier circuit, a self-powered switch circuit and a charge extraction circuit which are electrically connected in series in sequence, wherein:

[0008] The piezoelectric generator is equivalent to a current source i eq (t) and its parasitic capacitance C p A parallel circuit for converting vibration energy into electrical energy;

[0009] A resonant inductor L, located between the piezoelectric generator and the bridge rectifier circuit, and used to cooperate with the piezoelectric generator to generate electrical resonance;

[0010] A bridge rectifier circuit, located between the resonant inductor L and the self-powered switch circuit, for converting the alternating current generated by the piezoelectric generator into direct current;

[0011] A self-powered switch circuit, located between the bridge rectifier circuit and the charge extraction circuit, realizes a closing or opening action without an external control signal;

[0012] The charge extraction circuit is used to pick up the electric energy generated by the piezoelectric generator and supply it to the load R L powered by.

[0013] Furthermore, the bridge rectifier circuit includes at least four diodes D1, D2, D3, D4 electrically connected to each other in a bridge manner, and input port one and input port two; the input port one and input port two are respectively connected to the output end of the piezoelectric generator, and the input voltage at the input port one and input port two is equal to the voltage across the two ends of the piezoelectric generator.

[0014] Furthermore, the self-powered switching circuit 4 includes a diode D5, a capacitor C1, a transistor T1 and a transistor T2; the cathode of the diode D5 is respectively connected to the emitter of the transistor T1 and one end of the capacitor C1, the anode of the diode D5 is respectively connected to the base of the transistor T1 and the collector of the transistor T2, and the base of the transistor T2 is connected to the collector of the transistor T1.

[0015] Furthermore, the charge extraction circuit includes an inductor L1, a diode D6, a capacitor C2 and a load R L One end of the inductor L1 is connected to the emitter of the transistor T2, and the other end is connected to the other end of the capacitor C1 and the positive electrode of the diode D6, and the negative electrode of the diode D6 is connected to the capacitor C2 and the load R L , the capacitor C2 and the load R L They are connected in parallel with each other and the other end is connected to the emitter of transistor T2.

[0016] Furthermore, the diodes D1, D2, D3, and D4 are Schottky diodes with a conduction voltage drop of less than 0.7 volts.

[0017] Furthermore, in each half working cycle of the piezoelectric generator, the self-powered switch circuit is always in a disconnected state.

[0018] Furthermore, the piezoelectric generator is in any shape of a rectangle, a circle, an ellipse, a polygon, or a trapezoid.

[0019] Furthermore, the piezoelectric generator is composed of a piezoelectric material and an elastic matrix.

[0020] Furthermore, the piezoelectric material is made of any one of lead zirconate titanate piezoelectric material, piezoelectric composite material or polyvinylidene fluoride piezoelectric material, and the elastic matrix is ​​an aluminum matrix or a copper matrix.

[0021] The present invention also provides a method for optimizing the resonant inductance of a resonant piezoelectric power generation system, comprising the following steps:

[0022] Step 1: Equivalent the piezoelectric generator to a current source ieq (t) and its parasitic capacitance C p Parallel circuit and establish equivalent model;

[0023] Step 2, the equivalent model obtained in step 1 is electrically connected in series with the resonant inductor L, the bridge rectifier circuit, the self-powered switch circuit and the charge extraction circuit in sequence to form an overall circuit of the resonant piezoelectric power generation system;

[0024] Step 3, establishing a second-order differential equation about the output voltage of the piezoelectric generator according to Kirchhoff's theorem, and solving it to obtain a mathematical expression of the output voltage of the piezoelectric generator;

[0025] Step 4, taking the time t=T / 2 from the mathematical expression obtained in step 3, where T is the vibration period of the piezoelectric generator, to obtain a mathematical expression for the output voltage amplitude of the piezoelectric generator;

[0026] Step 5: The output voltage amplitude of the piezoelectric generator is regarded as a nonlinear function of the resonant inductance, and the optimal resonant inductance value is calculated using an optimization method to maximize the output voltage amplitude of the piezoelectric generator.

[0027] Furthermore, the optimization method adopts a gradient descent nonlinear function optimization method.

[0028] Compared with the prior art, the present invention is beneficial in that:

[0029] 1. The self-powered switching circuit of the resonant piezoelectric power generation system provided by the present invention can automatically close and open under the supply of electric energy generated by the piezoelectric generator, thereby realizing automatic control of the system of the present invention; a resonant inductor is added to the charge extraction circuit, and the optimal resonant inductor value can be obtained by optimizing the design of the resonant inductor, thereby greatly improving the power conversion efficiency of the traditional synchronous charge extraction circuit.

[0030] 2. The resonant inductance optimization method of the resonant piezoelectric power generation system provided by the present invention can obtain the optimal resonant inductance value. The optimal resonant inductance used can greatly improve the output voltage of the piezoelectric generator, improve the AC-DC conversion efficiency of the traditional synchronous charge extraction circuit for piezoelectric power generation, realize efficient vibration piezoelectric power generation, and thereby improve the system's power conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0032] The present invention is further described below in conjunction with the accompanying drawings:

[0033] Figure 1 It is a structural schematic diagram of the resonant piezoelectric power generation system of the present invention;

[0034] Figure 2 is a schematic diagram of an equivalent circuit of the piezoelectric generator of the present invention;

[0035] Figure 3 is the overall circuit diagram of the resonant piezoelectric power generation system of the present invention;

[0036] Figure 4 It is the waveform of the output voltage of the piezoelectric generator when the resonant inductor is connected;

[0037] Figure 5 It is the waveform of the output voltage of the piezoelectric generator when the resonant inductor is not connected;

[0038] Figure 6 is a flow chart of a resonant inductance optimization method of a resonant piezoelectric power generation system according to the present invention;

[0039] 1. Piezoelectric generator; 2. Resonant inductor L; 3. Bridge rectifier circuit; 4. Self-powered switch circuit; 5. Charge extraction circuit; 11. Current source i eq (t); 12. Parasitic capacitance C p ; 31, diodes D1, D2, D3, D4; 32, input port 1; 33, input port 2; 41, diode D5; 42, capacitor C1; 43, transistor T1; 44, transistor T2; 51, inductor L1; 52, diode D6; 53, capacitor C2; 54, load R L . DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] Embodiment 1

[0046] As attached Figure 1 A resonant piezoelectric power generation system shown in the figure comprises a piezoelectric generator 1, a resonant inductor L, a bridge rectifier circuit 3, a self-powered switch circuit 4 and a charge extraction circuit 5 which are electrically connected in series in sequence. The various parts are electrically connected in series to form an overall circuit of the resonant piezoelectric power generation system, wherein:

[0047] Piezoelectric generator 1, such as Figure 2 As shown, in this embodiment, it is equivalent to a current source i eq (t)11 and its parasitic capacitance C p 12 parallel circuit for converting vibration energy into electrical energy;

[0048] A resonant inductor L, located between the piezoelectric generator 1 and the bridge rectifier circuit 3, and used to cooperate with the piezoelectric generator 1 to generate electrical resonance;

[0049] The bridge rectifier circuit 3 is located between the resonant inductor L and the self-powered switch circuit 4, and is used to convert the alternating current generated by the piezoelectric generator 1 into direct current, and includes at least four diodes D1, D2, D3, D431 and an input port 1 32 and an input port 2 33 that are electrically connected to each other in a bridge manner. In the present embodiment, the diodes D1, D2, D3, D431 are Schottky diodes with a conduction voltage drop of less than 0.7 volts; the input port 1 32 and the input port 2 33 are respectively connected to the output end of the piezoelectric generator 1, and the input voltage at the input port 1 32 and the input port 2 33 is equal to the voltage at both ends of the piezoelectric generator 1;

[0050] The self-powered switch circuit 4 is located between the bridge rectifier circuit 3 and the charge extraction circuit 5, and realizes closing or opening action without the need for an external control signal; in this embodiment, the electric energy used by the self-powered switch circuit 4 is generated by the piezoelectric generator 1, and no external electric energy is required; the self-powered switch circuit 4 realizes closing or opening action without the need for an external control signal, and includes a diode D541, a capacitor C142, a transistor T143 and a transistor T244, the cathode of the diode D541 is respectively connected to the emitter of the transistor T143 and one end of the capacitor C142, the anode of the diode D541 is respectively connected to the base of the transistor T143 and the collector of the transistor T244, and the base of the transistor T244 is connected to the collector of the transistor T143;

[0051] The charge extraction circuit 5 is used to pick up the electric energy generated by the piezoelectric generator 1 as a load R L Power supply, which includes inductor L151, diode D652, capacitor C253 and load R L 54, one end of the inductor L151 is connected to the emitter of the transistor T244, and the other end is connected to the other end of the capacitor C142 and the positive electrode of the diode D652 respectively, and the negative electrode of the diode D652 is connected to the capacitor C253 and the load R L 54, the capacitor C253 and the load R L 54 are connected in parallel with each other and the other ends are connected to the emitter of transistor T244.

[0052] Preferably, the piezoelectric generator 1 can be of any shape, such as any one of a rectangle, a circle, an ellipse, a polygon, and a trapezoid; it is composed of a piezoelectric material and an elastic matrix. More specifically, the piezoelectric material is made of any one of lead zirconate titanate piezoelectric material, a piezoelectric composite material, or a polyvinylidene fluoride piezoelectric material, and the elastic matrix is ​​an aluminum matrix or a copper matrix.

[0053] The specific working process and principle of the system of the present invention are as follows:

[0054] 1) During the time from 0 to half cycle, the self-powered switch circuit 4 is in the disconnected state, and the current source i eq (t) 11 pairs of parasitic capacitance C p 12 and capacitor C142 are charged, so that the voltage across them increases continuously. At the same time, the resonant inductor L and the parasitic capacitor C p 12 produces resonance (capacitor C142 can be ignored), which can greatly increase the parasitic capacitance C at the half-cycle time p 12Amplitude of voltage across the terminals;

[0055] 2) At the half cycle, the self-powered switch circuit 4 is turned on, and the parasitic capacitor C p 12 and inductor L151 generate LC oscillation, and the charge flows from the parasitic capacitor C p 12 is transferred to the inductor L151;

[0056] 3) In the half cycle to one cycle time, the self-powered switch circuit 4 is disconnected, the inductor L151 and the capacitor C1 oscillate, and at the same time, due to the reverse cutoff of the diode D652, the energy is finally transferred to the load R L Provide power supply;

[0057] 4) In the half cycle to one cycle time, the current source i eq (t)11 Current flips, parasitic capacitance C p 12 and capacitor C253 are reversely charged, and processes 1), 2), and 3) are subsequently repeated.

[0058] Specific instructions for use: The resonant piezoelectric power generation system of the present invention is as follows: Figure 1 As shown, where C1 = 40μF, L1 = 0.2mH, C2 = 50μF, R L =100KΩ, i eq (t) = 0.001A, ω = 400π, D1 ~ D6 are all low-on voltage drop Schottky diodes (V D =0.6V), T1 and T2 use transistors with low on-state voltage (low on-state voltage here means on-state voltage <1.0V); the piezoelectric material uses piezoelectric ceramic PZT-5H sheet, and the base material is aluminum; the piezoelectric power generation structure is rectangular, and its equivalent capacitance C is actually measured p = 62μF, the optimal inductance is L = 1H, and the output voltage of the piezoelectric generator 1 when the resonant inductor is connected is as follows Figure 4 As shown, the output voltage of the piezoelectric generator 1 when the resonant inductor is not connected is as follows Figure 5 As shown, it can be seen that the output voltage amplitude of the piezoelectric generator 1 after connecting to the resonant inductor is significantly higher than that of the circuit in the prior art, indicating that the resonant piezoelectric power generation system provided by the present invention can effectively improve the power conversion rate of the piezoelectric generator.

[0059] Embodiment 2

[0060] like Figure 6 A resonant inductance optimization method for a resonant piezoelectric power generation system is shown, comprising the following steps:

[0061] Step 1: Piezoelectric generator equivalent modeling: The piezoelectric generator 1 is equivalent to a current source i eq (t)11 and its parasitic capacitance C p 12 parallel circuit and establish an equivalent model, parasitic capacitance C p The voltage across the terminals is V p (t);

[0062] Step 2, forming an overall circuit of the piezoelectric power generation system: the equivalent model obtained in step 1 is connected in series with the resonant inductor L, the bridge rectifier circuit 3, the self-powered switch circuit 4 and the charge extraction circuit 5 to form an overall circuit of the resonant piezoelectric power generation system; in each half working cycle of the piezoelectric generator 1, the self-powered switch circuit 4 is always disconnected, and the above overall circuit can be simplified to the inductor L1, the parasitic capacitor C p And the parallel connection of capacitor C1;

[0063] Step 3: Solve to obtain the output voltage of piezoelectric generator 1: According to Kirchhoff's theorem, establish the output voltage V of piezoelectric generator 1 p (t), and thus the output voltage V of the piezoelectric generator 1 is obtained p (t) mathematical expression;

[0064] Step 4: Obtain the output voltage amplitude of the piezoelectric generator 1: Substitute the output voltage V of the piezoelectric generator 1 obtained in step 3 p In the mathematical expression of (t), take time t=T / 2, T is the vibration period of the piezoelectric generator 1, and obtain the mathematical expression of the output voltage amplitude of the piezoelectric generator 1;

[0065] Step five, calculate the optimal resonant inductance value: regard the output voltage amplitude of the piezoelectric generator 1 as a nonlinear function of the resonant inductance, and use an optimization method to calculate the optimal resonant inductance value so that the output voltage amplitude of the piezoelectric generator is maximized; in this embodiment, the optimization method is a gradient descent nonlinear function optimization method.

[0066] The specific calculation and explanation are as follows:

[0067] 1) For the sake of convenience, it is assumed that the vibration source is in the form of sinusoidal excitation, and the piezoelectric generator 1 can be equivalent to a current source and parasitic capacitance C p 12 parallel circuit, such as Figure 2 As shown, where ω = 2π / T is the vibration angular frequency, is the initial phase;

[0068] 2) The equivalent circuit of the piezoelectric generator 1 is electrically connected in series with the resonant inductor L, the bridge rectifier circuit 3, the self-powered switch circuit 4 and the charge extraction circuit 5 in sequence to establish the overall circuit of the resonant synchronous charge extraction piezoelectric power generation system, such as Figure 3 shown.

[0069] Taking a positive half cycle of vibration as an example, the vibration displacement of the piezoelectric generator 1 increases from the equilibrium position to the peak value and then returns to the equilibrium position. The self-powered switch circuit 4 is disconnected for most of the time in the positive half cycle. p 12 and capacitor C142 complete the charging and discharging process, the parasitic capacitor C p The total capacitance after 12 and capacitor C142 are connected in parallel is:

[0070] C=C1+C P (1)

[0071] Assume that the parasitic capacitance C p 12 and the current of the resonant inductor L are i C (t) and i L (t), the two ends of the piezoelectric generator 1, that is, the parasitic capacitance C p The voltage across the two ends is V p (t), then

[0072]

[0073] Similarly, the relationship between the voltage and current across the resonant inductor L is shown in formula (3):

[0074]

[0075] According to Kirchhoff's current law:

[0076]

[0077] Substituting equation (3) and equation (4) into equation (2), we can get the differential equation:

[0078]

[0079] Solving the differential equation yields the following solution:

[0080]

[0081] Among them, C1 and C2 are arbitrary constants.

[0082] Substituting the boundary conditions, the unknowns in equation (6) can be obtained. The boundary conditions are:

[0083] V p (0)=0 (7)

[0084]

[0085]

[0086] Substituting equation (7) and equation (8) into equation (6), we can obtain:

[0087]

[0088]

[0089] To simplify the calculation, let:

[0090]

[0091]

[0092] Then formula (6) can be simplified as:

[0093]

[0094] After derivation, we can get:

[0095]

[0096] Substituting formula (9) into formula (15) yields:

[0097]

[0098] After sorting, we can get:

[0099]

[0100] From formula (17), we can further get and

[0101]

[0102]

[0103] Substituting equation (18) and equation (19) into equation (14), we can get C p The voltage expression at both ends is shown in formula (20):

[0104]

[0105] 3) Taking t = π / ω in equation (21), we can get V p The amplitude of (t) is:

[0106]

[0107] Further let λ = ω0 / ω, then equation (21) is transformed into:

[0108]

[0109] 4) When ω is given, it can be seen from formula (22) that: It is a nonlinear function of λ, and further a nonlinear function of the resonant inductance L. It can be solved by using traditional optimization methods such as gradient descent. The results show that when λ = 1 The value is the largest, at this time

[0110] The resonant inductance optimization method of the resonant piezoelectric power generation system provided by the present invention can obtain the optimal resonant inductance value. The optimal resonant inductance used can greatly improve the output voltage of the piezoelectric generator, improve the AC-DC conversion efficiency of the traditional synchronous charge extraction circuit for piezoelectric power generation, realize efficient vibration piezoelectric power generation, and thus improve the system's power conversion efficiency; at the same time, the system's power conversion efficiency is independent of the load.

[0111] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for optimizing the resonant inductance of a resonant piezoelectric power generation system, wherein the resonant piezoelectric power generation system comprises a piezoelectric generator (1), a resonant inductor, and a (2), a bridge rectifier circuit (3), a self-powered switch circuit (4) and a charge extraction circuit (5), wherein: Piezoelectric generator (1), equivalent to a current source (11) and its parasitic capacitance (12) Parallel circuit for converting vibration energy into electrical energy; resonant inductor (2), located between the piezoelectric generator (1) and the bridge rectifier circuit (3), and used to cooperate with the piezoelectric generator (1) to generate electrical resonance; the bridge rectifier circuit (3), located between the resonant inductor (2) and the self-powered switch circuit (4), used to convert the alternating current generated by the piezoelectric generator (1) into direct current; the self-powered switch circuit (4), located between the bridge rectifier circuit (3) and the charge extraction circuit (5), realizes a closing or opening action without an external control signal; the charge extraction circuit (5) is used to pick up the electric energy generated by the piezoelectric generator (1) and supply it to the load powered by; The self-powered switching circuit (4) comprises a diode (41) Capacitor (42) Transistor (43) and triode (44); the diode The negative electrode of (41) is connected to the transistor (43) emitter, capacitor (42) is connected to one end of the diode The positive electrode of (41) is connected to the transistor (43) Base, transistor (44) is connected to the collector of the transistor (44) The base and transistor (43) is connected to the collector; the charge extraction circuit (5) includes an inductor (51) Diode (52) Capacitor (53) and load (54); the inductor (51) One end of the transistor (44) is connected to the emitter, and the other end is connected to the capacitor (42) The other end, diode (52) is connected to the positive electrode of the diode (52) The negative electrode is connected to the capacitor (53) and load (54), the capacitor (53) and load (54) are connected in parallel and the other end is connected to the transistor (44) emitter; It is characterized by comprising the following steps: Step 1: Treat the piezoelectric generator (1) as a current source (11) and its parasitic capacitance (12) parallel circuit and establish an equivalent model; Step 2: Combine the equivalent model obtained in step 1 with the resonant inductor (2), a bridge rectifier circuit (3), a self-powered switch circuit (4) and a charge extraction circuit (5) are sequentially electrically connected in series to form an overall circuit of a resonant piezoelectric power generation system; Step 3: According to Kirchhoff's theorem, a second-order differential equation for the output voltage of the piezoelectric generator (1) is established, and the mathematical expression of the output voltage of the piezoelectric generator (1) is obtained by solving the differential equation: in, is the resonant inductor, is the capacitance, is the parasitic capacitance The voltage across the terminals, is an equivalent current source, is the vibration angular frequency, is the initial phase; Step 4: Take the time from the mathematical expression obtained in step 3 , is the vibration period of the piezoelectric generator (1), and the mathematical expression of the output voltage amplitude of the piezoelectric generator (1) is obtained. Solving the differential equation yields the following solution: in, , is an arbitrary constant; Step 5: The output voltage amplitude of the piezoelectric generator (1) is regarded as a nonlinear function of the resonant inductance, and an optimization method is used to calculate the optimal resonant inductance value so that the output voltage amplitude of the piezoelectric generator (1) is maximized.

2. The method for optimizing the resonant inductance of a resonant piezoelectric power generation system according to claim 1, characterized in that: The optimization method adopts a gradient descent nonlinear function optimization method.

3. The resonant inductance optimization method of a resonant piezoelectric power generation system according to claim 1, characterized in that: The bridge rectifier circuit (3) comprises at least four diodes electrically connected to each other in a bridge manner. , , , (31) and input port one (32), input port two (33); The input port one (32) and the input port two (33) are respectively connected to the output end of the piezoelectric generator (1), and the input voltage at the input port one (32) and the input port two (33) is equal to the voltage at both ends of the piezoelectric generator (1).

4. The method for optimizing the resonant inductance of a resonant piezoelectric power generation system according to claim 3, characterized in that: The diode , , , (31) is a Schottky diode with a forward voltage drop of less than 0.7 volts.

5. The method for optimizing the resonant inductance of a resonant piezoelectric power generation system according to claim 3, characterized in that: In each half working cycle of the piezoelectric generator (1), the self-powered switch circuit (4) is always in a disconnected state.

6. The method for optimizing the resonant inductance of a resonant piezoelectric power generation system according to claim 5, characterized in that: The piezoelectric generator (1) consists of a piezoelectric material and an elastic matrix.

7. The method for optimizing the resonant inductance of a resonant piezoelectric power generation system according to claim 6, characterized in that: The piezoelectric material is made of any one of lead zirconate titanate piezoelectric material, piezoelectric composite material or polyvinylidene fluoride piezoelectric material, and the elastic matrix is ​​an aluminum matrix or a copper matrix.

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