A Multi-Source Energy-Harvesting Power Management System with a Single Shared Inductor

A single-inductor multi-source energy harvesting system that can harvest three types of ambient energy was presented. The system can self-supply using an integrated self-starting circuit that does not require an external battery. It performs hybrid modulation of pulse-frequency modulation (PFM) and pulse-width modulation (PWM) and realizes adaptive asynchronous control for input and output, achieving higher system stability and better energy aggregation. Adaptive maximum power point tracking (MPPT) was implemented to generate inductor charging control signals with different frequencies and duty cycles according to different input sources, enabling the inductor to operate in discontinuous mode (DCM) under different input conditions. The energy harvesting system was designed using a 0.18-mu m CMOS process. The simulation results show that the system can realize low-voltage self-startup as low as 200mV and can provide a stable output of 1.4V to the load with a 1V harvested voltage to self-supply. The highest conversion efficiency of the system is 76.43%@R-load=10k Omega, and the average power consumption in sleep mode is 2.38 mu W.