Optimal Design Of Vibration Energy Recovery Circuit Based On Piezoelectric Materials

At present,with the rapid development of micro-electromechanical system(MEMS)technology,most portable electronic devices and wireless sensors are powered by chemical batteries,but the chemical batteries need to be replaced and recycled regularly,which makes the technology of vibration energy harvesting develop rapidly.Piezoelectric vibration energy harvesting technology is easy to integrate,can achieve miniaturization,and has a high energy density,so it is widely concerned.In this paper,the harvesting circuit of piezoelectric energy harvesting system is studied,and an improved energy harvesting circuit is proposed.The main work is as follows:(1)Based on the theory of piezoelectric effect and piezoelectric equations,the electromechanical coupling model of "spring-mass-damper" is established.Theoretically,the working principle of standard energy harvesting circuit,synchronous charge extraction circuit,series synchronous switch inductance circuit and parallel synchronous switch inductance circuit is analyzed,under the condition of constant excitation displacement and force,the expression of maximum harvesting power is derived.(2)An improved energy harvesting circuit with double intermediate capacitors for piezoelectric vibration is proposed.Under the condition of constant excitation force and constant excitation displacement,the maximum harvesting power of the circuit is deduced and compared with the four energy harvesting circuits.Through theoretical analysis,the results show that the output power of the improved double intermediate capacitor energy harvesting circuit is independent of the load,and has good adaptability to the load,which is about twice the harvesting power of the synchronous charge extraction circuit.(3)The simulation circuit model of piezoelectric chip is built in Multisim,and five kinds of energy harvesting circuits are simulated and verified.Under the condition of constant excitation displacement,the voltage simulation waveforms and the maximum harvesting power of each harvesting circuit are obtained.Set up the harvesting circuit experiment platform,respectively verify five kinds of energy harvesting circuits,and get the harvesting power of each circuit under different loads.The experimental results are compared with the theoretical analysis to verify the better performance of the improved double intermediate capacitor energy harvesting circuit.