A Zero-Crossing Detection Circuit for Energy Harvesting

Synchronized switch harvesting on capacitors (SSHC) circuit can effectively improve the efficiency of piezoelectric energy harvesting circuit. However, its output power and voltage flip efficiency are deeply affected by the accuracy of zero-crossing detection circuit. Based on SSHC circuit using potential comparison method, a piezoelectric energy harvesting circuit composed of piezoelectric element, zero-crossing detection circuit, pulse generation circuit, full-bridge rectifier and load is designed. The zero-crossing detection circuit using sampling resistance method can accurately determines the closing time of switches and improve the accuracy of this circuit. The simulation results show that this circuit can effectively improve the voltage flip efficiency and output power, too. In the case of a load of 100kΩ, the output power of proposed circuit is 368.72μW. Compared with the single-capacitor SSHC circuit using potential comparison method, it is improved by 46.08%.