High Precision Hysteresis Controlled MPPT Circuit for Vibration Energy Harvesting

Abstract

A high precision hysteresis controlled maximum power point tracking (HPHC-MPPT) circuit for vibration energy harvesting is proposed in this paper. It is realized with the fractional open-circuit voltage (FOCV) MPPT method, and a hysteresis comparator based controller is used to make a precise hysteresis voltage window, which is including 1/2 open circuit voltage of the piezoelectric transducer (PZT) voltage after rectifier. An adaptive sampling rate controller is added to reduce the sampling power consumption. Energy management unit is used to transfer energy from rectifier output capacitor to energy storage capacitor with high efficiency. The proposed circuit is designed and simulated with SMIC 0.18μm process. The results show that the MPPT efficiency is high to 99.45%, and the maximum conversion efficiency can reach 94.2% with a wide variations of the input vibration energy and the system load.