Research On High Efficiency Piezoelectric Energy Harvesting System Based On P-SSHI And Cold Startup

In recent years,with the development of Internet of Things technology,more and more researchers have focused attention on energy harvesting technology,to solve the self-powered problem in wireless sensor network nodes.Among the various kinds of energy,vibration energy has attracted more and more attention because of its advantages such as universality,high energy density and high conversion efficiency.In order to make full use of the collected energy,it is necessary to correct and manage the energy through interface circuit.Among the interface circuits of vibration energy harvesting system,parallel synchronized switch inductor technology(P-SSHI)has been widely used because of its high energy collection efficiency.This circuit not only realizes low circuit complexity,low power consumption,small size,long life,easy integration,etc.,and can also solve the problem of autonomous power supply for many wireless sensor network nodes.However,the problem of cold startup still exists in P-SSHI interface circuit.When the whole system is operated in a low environmental vibration excitation,the collected energy will not provide power to the interface circuit normally.Based on the shortcomings of vibration energy harvesting field,this paper proposes a highefficiency piezoelectric energy harvesting system with cold start function.This system uses a PSSHI interface circuit to increase the collected energy power of rectifier to from piezoelectric transducer.Instead of traditional diodes,active diodes are used to reduce the turn-on voltage drop and rectification losses,which greatly improves the rectification efficiency.A charge pump is also applied to provide a high voltage for the fully start of system.At the same time,based on the theory of piezoelectric transducer separation electrode,a cold startup circuit is designed to ensure that the system achieve cold startup and complete self-power supply under low excitation level.Finally,by adjusting the output voltage within the dynamic range,the system can realize the function of multiple output loads.This paper adopts TSMC 0.18?m CMOS technology and uses Cadence spectre simulation platform for design and simulation.The simulation results show that the P-SSHI rectifier structure used in this system reaches a voltage flip efficiency of 85%,and the output power is significantly improved which is 5.8 times of the output power in traditional full-bridge rectifier circuit under the same excitation conditions.In addition,the system can simultaneously output two stable voltages of 1.2V and 1.8V to power different loads.