阅读说明：本技术 一种无二次翻转的自供能压电能量收集接口电路 (Self-powered piezoelectric energy collection interface circuit without secondary overturning ) 是由 张斌 柳洪生 高峰 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种无二次翻转的同步开关电感能量收集接口电路,包括压电元件等效电学模型、同步开关电感模块、整流桥模块以及滤波稳压单元。该电路利用由三极管、电容为主体组成的峰值检测开关电路使得压电元件与电感形成高频电容-电感振荡回路,电压翻转时刻与其运动位移的极值时刻实时同步,以此提升压电换能器输出电压；利用二极管的单向导电性,消除现有的自供能同步开关电感电路中存在的“二次翻转”现象,可以有效地避免“二次翻转”过程对能量收集所造成的不利影响；本发明又将压电元件正负方向的峰值检测电容复用,减少了该类型电子元件的数目。(The invention discloses a synchronous switch inductor energy collection interface circuit without secondary turnover, which comprises a piezoelectric element equivalent electrical model, a synchronous switch inductor module, a rectifier bridge module and a filtering and voltage stabilizing unit. The circuit utilizes a peak value detection switch circuit which is mainly composed of a triode and a capacitor to enable a piezoelectric element and an inductor to form a high-frequency capacitor-inductor oscillating circuit, and the voltage overturning moment is synchronous with the extreme value moment of the motion displacement of the piezoelectric element in real time so as to increase the output voltage of the piezoelectric transducer; the unidirectional conductivity of the diode is utilized to eliminate the phenomenon of 'secondary turnover' in the existing self-powered synchronous switch inductance circuit, so that the adverse effect of the 'secondary turnover' process on energy collection can be effectively avoided; the invention also reuses the peak detection capacitance of the piezoelectric element in the positive and negative directions, thereby reducing the number of the electronic elements of the type.)

1. The utility model provides a self-powered synchronous switch inductance circuit of no secondary upset which characterized in that: the circuit comprises an equivalent electrical module of the piezoelectric transducer, a synchronous switch inductance module, a full-bridge rectifier bridge module and a filtering and voltage stabilizing unit.

2. The self-powered synchronous switched inductor circuit without double flipping as claimed in claim 1, wherein: the synchronous switch inductance module comprises a peak detection capacitor, four diodes, two NPNs, two PNP triodes and two inductors; the peak detection capacitor C₁Much smaller than the internal capacitance C of the piezoelectric element_p(ii) a The emitting electrodes of the two NPN triodes are respectively connected with two electrodes of the capacitor, and the base electrodes are connected with the equivalent electrical model of the piezoelectric element to form a voltage peak value detection circuit which can detect the voltage peak value of the piezoelectric element; the diode D₁、D₂The base electrodes and the emitter electrodes of the two NPN triodes are respectively connected in parallel, wherein the cathode of the diode is connected with the base electrodes of the triodes, and the anode is connected with the emitter electrode, so that the capacitor C can be realized₁And the unidirectional conductivity of the circuit is ensured.

3. The self-powered synchronous switching inductor circuit without double flipping as claimed in claim 2, wherein: PNP triode Q₃Base and Q of₁Is connected with the collector of a triode Q₄Base and Q of₂The emitting electrodes of the two PNP triodes are connected with the grounding point of the circuit, the collecting electrodes respectively correspond to the positive electrode and the negative electrode which are connected with the equivalent electrical model of the piezoelectric element to form a positive electrode (Q)₄) Negative (Q)₃₎The electronic switch, wherein the drive switch signal is provided by the collector of two PNP triodes; the inductor L₁And L₂The two inductors are symmetrically connected to two sides of the grounding point; the diode D₃And D₄The two diodes are respectively connected in series with the input end of the piezoelectric element and the other end of the inductor, and the cathodes of the two diodes are connected with the inductor, so that the one-way conductivity of the circuit is ensured, and the reverse overturning of the capacitance-inductor high-frequency resonance circuit is avoided.

4. According to claim1 the self-energized synchronous switch inductance circuit who does not have secondary upset, its characterized in that: the full-bridge rectifier bridge circuit is composed of four diodes D₅～D₈The rectifier bridge is connected with the input end of the equivalent electrical model of the piezoelectric element, and can rectify the alternating current output by the piezoelectric element into direct current.

5. The self-powered synchronous switched inductor circuit without double flipping as claimed in claim 1, wherein: the filtering voltage stabilizing unit is composed of a capacitor with a large capacitance value, two poles of the capacitor are respectively connected with two ends of the rectifier bridge, the load resistor is also connected in parallel with two ends of the capacitor, and when the charging process and the discharging process of the capacitor reach a dynamic balance type, the filtering voltage stabilizing processing of the direct current output by the rectifier bridge can be realized, and a stable voltage is output.

Technical Field

The invention relates to the technical field of energy conversion, in particular to a self-powered piezoelectric energy collection interface circuit for eliminating a secondary overturning phenomenon.

Background

At present, the development of wireless sensing technology is mature, and some sensors are gradually applied to various fields of production, life and the like. The traditional energy supply mode represented by the battery has the defects that the traditional energy supply mode needs to be disassembled and replaced when the traditional energy supply mode reaches the service life due to limited capacity, the environment is easily polluted, and the like, and the energy supply requirement of the wireless sensing node is gradually not met. Therefore, it has become a research hotspot to draw energy from the environment and convert it into electrical energy that can be utilized to power wireless sensors. Among them, the piezoelectric energy collection technology is considered as one of the most promising ways to supply power to wireless nodes because of its advantages such as large energy density and no influence from weather and environment.

However, since the output current of the piezoelectric transducer is an alternating current and the internal impedance is very large, impedance matching is difficult, and thus the converted electric quantity is difficult to extract, and an interface circuit must be connected to improve the energy conversion efficiency. In the field of research of energy collection interface circuits, a classic standard rectifier bridge circuit can rectify alternating current output by a piezoelectric transducer into stable direct current, but when a rectifier bridge is disconnected, a charge neutralization phenomenon exists, so that the output level of the circuit is low; the synchronous switch inductance circuit can effectively utilize the internal capacitance and inductance of the piezoelectric transducer to form a capacitance-inductance high-frequency oscillation circuit, when the output current of the piezoelectric transducer passes through a zero point or the voltage reaches an extreme value (when the deformation displacement of the piezoelectric element reaches the extreme value), 1/2 resonance cycles of the switch are closed, the output voltage of the piezoelectric element is overturned, and therefore the phenomenon of charge neutralization waste in a standard rectifier bridge is avoided. In the circuit, the switch control mainly depends on an external sensor and a microcontroller, and in order to save the complex devices, a peak detection switch circuit can be adopted in the circuit to replace a switch to realize voltage peak detection and complete power supply overturning action, namely self-power supply. In the self-power research of the synchronous switch inductance circuit, two peak value detection switch circuits are generally adopted to realize the voltage peak value detection in the positive and negative directions, however, when the voltage overturning process in one direction is finished, the voltage has the tendency of reverse overturning, and at the moment, due to the reverse cut-off function of a diode in the loop, the loop cannot be conducted; however, in the peak detection switch circuit on the other side, because a very small parasitic capacitance exists between the electrodes of the triode, the piezoelectric element and the inductor can form a capacitance-inductance resonant circuit with very short time, namely a 'secondary overturning' phenomenon; the presence of this phenomenon not only makes the inverted voltage smaller, but also increases the time for the voltage to reach the rectified voltage, i.e., reduces the energy extraction time, thereby causing energy dissipation, which is more prominent when the internal capacitance of the piezoelectric element is extremely small. Therefore, in the research on the self-powered synchronous switch inductance circuit, a self-powered circuit capable of eliminating 'secondary turnover' needs to be designed, and the self-powered synchronous switch inductance circuit has important significance for improving energy output power and energy conversion efficiency.

Disclosure of Invention

The invention aims to make up the defects of the existing self-powered synchronous switch inductance circuit technology, and provides a self-powered synchronous switch inductance energy collection interface circuit without secondary turnover, aiming at eliminating energy loss caused by secondary turnover. According to the self-powered energy storage device, alternating current generated by the piezoelectric transducer can be converted into stable direct current through the circuit, and then the stable direct current is supplied to the energy storage unit for energy storage or directly supplied to a load, so that the problem that the conventional energy supply mode needs to be frequently replaced is solved, and long-term self-power supply is realized.

The technical scheme of the invention is as follows:

the utility model provides a self-power synchronous switch inductance energy collection interface circuit of no secondary upset which characterized in that: the circuit comprises an equivalent electrical module of a piezoelectric transducer, a synchronous switch inductance module, a full-bridge rectifier bridge module and a filtering and voltage stabilizing unit; the piezoelectric transducer equivalent electricity module is formed by connecting an equivalent alternating current source, a capacitor and a resistor in parallel; the synchronous switch inductance module comprises a peak detection capacitor, four diodes, two NPNs, two PNP triodes and two inductors; the peak detection capacitor C₁Much smaller than the internal capacitance C of the piezoelectric element_p(ii) a The emitting electrodes of the two NPN triodes are respectively connected with two electrodes of a capacitor, and the base electrodes are connected with the equivalent electrical model of the piezoelectric element to form the structureA voltage peak detection circuit capable of detecting a voltage peak of the piezoelectric element; the diode D₁、D₂The base electrodes and the emitter electrodes of the two NPN triodes are respectively connected in parallel, wherein the cathode of the diode is connected with the base electrodes of the triodes, and the anode is connected with the emitter electrode, so that the capacitor C can be realized₁The charging and discharging of the circuit are carried out, and the unidirectional conductivity of the circuit is ensured; the PNP triode Q₃Base and Q of₁Is connected with the collector of a triode Q₄Base and Q of₂The emitting electrodes of the two PNP triodes are connected with the grounding point of the circuit, the collecting electrodes respectively correspond to the positive electrode and the negative electrode which are connected with the equivalent electrical model of the piezoelectric element to form a positive electrode (Q)₄) Negative (Q)₃) The electronic switch, wherein the drive switch signal is provided by the collector of two PNP triodes; the inductor L₁And L₂The two inductors are symmetrically connected to two sides of the grounding point; the diode D₃And D₄The two diodes are respectively connected in series with the input end of the piezoelectric element and the other end of the inductor, and the cathodes of the two diodes are connected with the inductor, so that the one-way conductivity of the circuit is ensured, and the reverse overturning of the capacitance-inductor high-frequency resonance circuit is avoided; the full-bridge rectifier bridge circuit is composed of four diodes D₅～D₈The composition can further adopt a Schottky diode to reduce the conduction voltage drop of the diode, the input end of a rectifier bridge is connected with the input end of the equivalent electrical model of the piezoelectric element, and alternating current output by the piezoelectric element can be rectified into direct current; the filtering voltage stabilizing unit is composed of a capacitor with a large capacitance value, two poles of the capacitor are respectively connected with two ends of the rectifier bridge, the load resistor is also connected in parallel with two ends of the capacitor, and when the charging process and the discharging process of the capacitor reach a dynamic balance type, the filtering voltage stabilizing processing of the direct current output by the rectifier bridge can be realized, and a stable voltage is output.

The invention provides a self-powered synchronous switch inductor energy collection interface circuit without secondary turnover, which has the advantages that:

(1) the circuit provided by the invention can realize voltage turnover at the correct time without external sensing equipment and a microcontroller, namely self-powered.

(2) The invention reuses the positive and negative peak detection capacitors of the synchronous switch inductance module, thereby reducing the number of electronic elements.

(3) The circuit provided by the invention can normally work without an external starting power supply, namely cold starting.

(4) The circuit provided by the invention can effectively eliminate the phenomenon of 'secondary overturning', and has the characteristics of high output voltage, high energy conversion efficiency and the like.

Drawings

FIG. 1 is a schematic diagram of a self-powered synchronous switch inductor energy harvesting circuit without double flipping according to the present invention;

FIG. 2 is a waveform diagram of a theoretical operation of a self-powered synchronous switch inductor energy harvesting circuit without secondary flipping in a half cycle according to the present invention;

FIG. 3 is an enlarged waveform of the current of the circuit in the energy extraction state;

FIG. 4 is a waveform diagram of the voltage and current amplification of the circuit at the voltage inversion stage.

Detailed Description

In order to make the circuit and the technical problems and advantages of the present invention more clear, the present application will be further described in detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 shows a self-powered synchronous switch inductor energy harvesting circuit without double flipping according to the present invention. As shown in fig. 2, the whole operation process of the circuit is divided into four steps by taking half of the energy collection period as an example according to the operation mode of the circuit.

The following describes the four operations of the circuit in detail:

1. and (3) a natural charging process: at t₀-t₁Stage, inverted piezoelectric element voltage V_pHas not yet reached the rectified voltage V_rectAt this time, as the piezoelectric element moves in the forward direction, the equivalent current source i_pThe circuit begins to charge forward. However, the bridge is not yet turned on and the equivalent current source i_pAnd the internal capacitance C of the piezoelectric element_pPeak detecting capacitor C₁A charging loop is formed, and the voltage of the two capacitors is continuously increased. Current transmission path is i_p+→C_p∥R_P→i_p-，i_p+→Q₁→C₁→D₂→i_p-。

2. The energy extraction process comprises the following steps: when the voltage across the piezoelectric element reaches the rectified voltage V_rectWhile, the equivalent current source i_pStill in the forward charging state, i.e. t in fig. 2₁At the moment, the rectifier bridge is conducted, and at the moment, current passes through the filter capacitor C_rectAnd a load R_LEnergy extraction is started. Capacitor C_pAnd C₁The voltage at the two ends is kept unchanged due to the clamping action of the rectifier bridge and the filter capacitor until the rectifier bridge is cut off. The energy extraction phase corresponds to t of fig. 2₁-t₂The current waveform is enlarged as shown in fig. 3. At this time, the current transmission path is i_p ⁺→D₅→C_rect∥R_L→D₇→i_p ^-。

3. Additional open circuit process: to t in FIG. 2₂At the moment, the piezoelectric element moves to the positive value and starts to move reversely, and the equivalent current source i_pJust after the zero point, the reverse charging is started, and the voltage across the piezoelectric element is reduced and is less than V_rectThus, the rectifier bridge is cut off and the energy extraction phase is ended. The piezoelectric element is in an open circuit state, the voltage across the piezoelectric element continues to drop, and the current path is i_p ^-→C_p∥R_P→i_p ⁺And a capacitor C₁Due to the diode D₂Reverse cut-off NPN type triode Q₂And the voltage of the capacitor is kept unchanged all the time when the capacitor is not conducted.

4. And (3) voltage turning stage: when t in FIG. 2 is reached₃At time, the capacitance C of the piezoelectric element_pVoltage ratio peak detection capacitor C₁Voltage of the base emitter turn-on threshold voltage V of the small triode_beTime, NPN triode Q₂The base emitter PN junction is in forward bias conduction, and the PNP triode Q is connected with the base emitter PN junction₄The base emitter PN junction is also in a forward bias state, and the piezoelectric element capacitor C_pAnd an inductance L₁Forming an LC oscillating circuit corresponding to t in FIG. 2₃-t₄Stage, the amplified waveform of which is shown in FIG. 4, equivalent current source i_pStill in the reverse state, so that the reversed voltage magnitude continues to increase until the next operating phase. The energy transmission path is C_p→D₃→L₁→Q₄→C_p(ii) a The peak detection capacitor also begins to discharge, its energy transfer path is C₁→D₁→D₃→L₁→Q₄→Q₂→C₁. After 1/2 oscillation periods, the voltage of the piezoelectric element is changed from V_MIs turned to-V_mAt this time, the operation process of the negative half cycle is started, and the principle is similar to that of the positive half cycle.

In the existing self-powered synchronous switch inductance circuit, in order to realize the voltage peak value detection in the positive and negative directions, a capacitor is respectively adopted in the positive and negative voltage peak value detection circuits of the piezoelectric elements; preferably, the circuit proposed by the present invention reuses the positive and negative voltage peak detection capacitance, reducing the number of this type of electronic components. In the existing self-powered synchronous switch inductance circuit, after the voltage overturning stage in one direction is finished, due to the effect of parasitic capacitance between electrodes of a triode, a piezoelectric element and an inductance can immediately form an oscillating circuit in the opposite direction, namely, the process of 'secondary overturning', and the existence of the phenomenon can increase energy dissipation and reduce energy extraction time; preferably, the circuit proposed by the present invention utilizes the unidirectional conductivity of the diode to limit the reverse transfer of current, so that after the voltage reversal is completed, all the inductive loops in the circuit are in an open circuit state, and therefore, the reversed voltage is not reduced any more, the time taken for reaching the rectified voltage is reduced, that is, the time for energy extraction is increased, and therefore, the energy conversion efficiency is higher.

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the present application.