Research And Design Of Piezoelectric Energy Collection System For Cold Start

In the past decade,with the application of wireless sensor networks,implantable medical devices and portable electronic devices,piezoelectric vibration energy harvesting technology has aroused extensive research interest in the realization of autonomous wireless sensor nodes.In order to make full use of the harvested energy,it is necessary to calibrate and manage the energy through the interface circuit.Among all the active interface circuits,the synchronized switch harvesting on inductor(SSHI)circuit is widely used because of its high energy efficiency.Because the interface circuit needs a stable DC power supply,and the whole system has no charge at the beginning of implementation or after a period of time,there is no input vibration excitation,at this time,the system will have a cold start problem,so that the whole system can not work normally.In this paper,based on the piezoelectric effect of piezoelectric materials and the theoretical model of piezoelectric cantilever structure,the full bridge rectifier circuit(FBR),synchronous charge extraction circuit,parallel synchronized switch harvesting on inductor circuit and series synchronized switch harvesting on inductor circuit are introduced respectively.Based on the advantages of parallel synchronized switch harvesting on inductor circuit in energy harvesting,and in view of the problems in cold start of the circuit,a piezoelectric energy harvesting system with cold start function is proposed,which can dynamically improve the open circuit voltage generated by the piezoelectric sensor in cold state and make the system start at a lower level of excitation.At the same time,the energy collected by the system can be processed to supply power to the external load.Secondly,this paper introduces the proposed piezoelectric energy harvesting system from several modules,such as parallel synchronized switch harvesting on inductor interface circuit,level shifter and DC-DC converter,cold start circuit and multi load circuit,and further introduces the working principle and process of the circuit through system modeling.Finally,the proposed system is built and simulated on candance software.The simulation results show that in order to start the system in cold state,the required excitation level is reduced by at least 50%.The experimental results are consistent with the theoretical analysis.