A Power Management System for Hybrid Energy Harvesting From Multiple Multitype Sources and Ultrawide Range Source Tracking

This article presents a power management system (PMS) for hybrid energy harvesting from multiple multitype sources. Three key features of the proposed approach are 1) a simple architecture for hybrid energy harvesting from multiple multitype sources by sharing a single inductor, 2) a backup power controller (BPC) for recycling surplus energy, and 3) an efficient boost-buck conversion (B2C) mode for tracking multiple sources within a single cycle. The power stages of the PMS consist of an active bias-flip rectifier (ABFR) for ac sources, three input low-voltage boost converters (3LVBC), and a high-voltage buck converter for dc sources. The B2C mode efficiently combines the operation of the 3LVBC and HVBC. By sharing an inductor in B2C mode, the ABFR increases the overall input power (PIN) by aggregating the power from the hybrid sources. The proposed PMS operates under four modes depending on the load conditions detected by the BPC. This approach improves the average harvesting efficiency using the auxiliary output paths and two storage nodes. For per-source maximum power point tracking, adaptive impedance matching and perturb and observe techniques are used. The integrated circuit (IC) part of the PMS is fabricated in a 180 nm process. The measured tracking efficiency is higher than 92% for a wide source resistance range from 2 Omega to 2 k Omega (1000x range). An end-to-end efficiency of up to 92.5% is achieved. The energy harvesting from multiple multitype sources significantly extends the output power range from 0.053 mu Wto 132600 mu W. All the functions of the IC are realized with only 900 nW.