Dual-Source Energy Harvesting System using TDM with Dynamic MPPT and Wide-Range ZCS

This paper presents an efficient dynamic technique for energy combining from thermoelectric generators (TEG) and piezoelectric transducers (PZ). A dual-source maximum-power-point-tracking (MPPT) unit working in analogues way to phase-locked loops (PLL) is proposed. The dynamic MPPT achieves global maximum power extraction by matching both sources impedance varying from 1.5 Ω to 43 Ω for a thermoelectric generator cell and from 2 kΩ to 44 kΩ for a piezoelectric cell with only 2% power loss. A wide-range zero-current-switching (WR-ZCS) circuit is proposed to tune inductor discharging time with a good resolution using a digitally-tuned delay cell providing 30 ns and 100 ns delays. With an output control unit and with the aid of a kick start voltage a self-biased operation is obtained while the output voltage is regulated at 2.5 V.