A Study Of Piezoelectric Energy Harvesting Interface Circuit Based On Synchronized Switch Technology

In recent years,the application of wireless sensor networks has received more and more attention.With the increasing number of wireless sensor network nodes,the power supply for the wireless sensor nodes becomes an important issue.In many systems,primary batteries are used as the power supply.However,their life time is limited due to their limited energy capacity.When there are thousands of wireless sensor network nodes,the use of the primary batteries will cause environmental problem.In order to solve the power supply problem,energy harvesting technology from the environment are being studied.Energy harvesting from the environment can utilize the solar energy,wind energy,heat energy and vibration energy,etc.Among them,the vibration energy is very extensive in people's day life,which can be generated by human walking and machine operation,etc.Piezoelectric elements are often used to convert vibration energy into electrical energy.Studies have shown that piezoelectric materials have a power density of up to milli-watts per cubic centimeter and can offer enough energy to power wireless sensor network nodes.Moreover,compared with electromagnetic and electrostatic vibration energy harvesting technology,the piezoelectric energy harvesting system has advantages such as simple structure and easy integration.Piezoelectric elements in energy harvesters usually generate an alternating voltage,and cannot be directly used to power the electronic equipment The rectifier bridge is the most commonly used piezoelectric interface circuit,but the harvested power is relatively low and is significantly affected by the load.Many researchers have studied the interface circuits of piezoelectric energy harvesting system,but the power consumptions of the interface circuits are still too large,which will consume part of the harvested energy and reduce the whole system efficiency.The focus of this paper is to design a low power-consumption piezoelectric interface circuit.Based on the parallel synchronized switching harvesting on inductor(P-SSHI)technology,the piezoelectric harvesting interface circuit is designed.The experimental results show that the maximum energy harvested by the designed interface circuit is 2.87 times of the traditional rectifier circuit.The power consumption of the whole interface system is as low as 10.6?W.A circuit for load matching is also designed with the P-SSHI interface circuit.The experimental results show that the harvested energy of the designed impedance-matched interface circuit is 1.47 times of the impedance-matched rectifier circuit.The proposed interface circuit can provide a stable 2.5V voltage for the wireless sensor network nodes.