A 96.5%-Power-Efficiency Hybrid Buck-Boost Photovoltaic Energy Harvester Employing Adaptive FOCV MPPT Control for >98% MPPT Efficiency Across a 10,000× Dynamic Range

Abstract

We present a photovoltaic (PV) energy harvesting (EH) system achieving both high maximum-power-point-tracking efficiency (MPPT) and high power-conversion efficiency (CONV) in an ultra-wide input power (PIN) range. Instead of a complex and power-hungry hybrid MPPT, an MPPT based on an adaptive fractional open-circuit voltage (FOCV) method is used to tune the fraction k based on PIN with little power overhead. Also, a hybrid topology is modified to work as a buck-boost converter to maintain high CONV at low PIN by combining three different control techniques. Zero-current-detection (ZCD) is performed with actively changing the tuning resolution to reduce control bit size and response time.