Study Of Energy Harvesting Circuit Based On Synchronous Switching Inductive Technology

Energy harvesting technology is one of the key technologies for the micromation and practicality of wireless system and portable electronic devices. Among all kinds of energy harvesters, the vibration energy harvesting technology has been developed rapidly in MEMS applications because of its higher energy density, higher power output, and easily to be integrated. This paper, based on CMOS integrated circuit, proposed two nonlinear energy extraction interface circuits with higher harvesting efficient, lower power consumption, and higher density of integration. The main contents and results are as follows:(1) The theoretical harvested power of four kinds of classic interface circuit:has been deduced:Standard, SECE, Parallel-SSHI, and Series-SSHI. Their maximum output power with the optimal load matching range are analyzed. Conclusion indicates:among the four kinds of classic interface circuit, the harvested power of Parallel-SSHI circuit is the maximum, and the harvested power of SECE circuit is not influenced by load.(2) An efficient piezoelectric energy harvesting chip has been designed based on Parallel Synchronized Switch Harvesting on Inductance (P-SSHI) interface circuit. The proposed circuit includes a P-SSHI circuit, a control circuit and a signal conditioning circuit. This chip has many advantages, such as less switch controlling signals, simpler control circuit, and better stability. Besides, the design of output end can inhibit the current backflow effect effectively, improving the power extraction capability. The simulation results based on 0.5?m CMOS process show that the chip collects the maximum output power to 178.2 ?W, which is able to extract 10 times more than a conventional full-bridge rectifier.(3) A new two-stage energy harvesting interface circuit has been designed and the working process of which has been fully elaborated. The optimal switching time of the control switch has been analyzed to bring the energy harvested power up to the maximum. The two-stage energy harvesting interface circuit not only enhance power harvesting efficiency but also overcome the disadvantage of the front stage single energy harvesting circuit output power which will be influenced by load effect. Finally, the cadence simulation verified the function of the circuit.(4) The experimental measurements has been carried out to measure the actual harvested power of four kinds of classic single stage energy harvesting circuit when the generator is driven with constant vibration displacement, verified the fit of actual recovery and theoretical analysis.