A Single Inductor Dual Path Three Switch Converter With Energy Recycling Technique for Light Energy Harvesting
This work proposes an energy recycling (ER) technique for power management among a photovoltaic (PV) module, battery, and load in light energy harvesting systems. The ER technique delivers all harvested PV energy directly to the load with surplus energy recycled from the load to the battery, and can eliminate inductor sharing power switches in single inductor dual input dual output (SIDIDO) converters. Accordingly, the proposed dual path 3 switch (2P3S) converter, which operates in discontinuous conduction mode and regulates load voltage by constant on time pulse skipping modulation, was developed. Under dynamic PV power P<sub>P</sub> and load power P<sub>L</sub> profiles, the 2P3S converter's advantageous applications are identified by comparing efficiencies of state of the art SIDIDO converters. The overall efficiency under static P<sub>P</sub> and P<sub>L</sub> profiles and indirect path efficiency under dynamic P<sub>P</sub> and P<sub>L</sub> profiles are maximized by optimizing switch sizes and on time. The chip has three power switches and a controller employing low power circuits, and is fabricated in 0.5 mm CMOS process with 0.5 mm<sup>2</sup> active area. The measured controller current is 0.85 mA. Under static P<sub>P</sub> and P<sub>L</sub> profiles, for P<sub>P</sub> of 40 mW, efficiency is 80.7% to 95.0% for 0 mW to 20 mW load power. Compared with other state of the arts, the 2P3S converter has the highest efficiency under static P<sub>P</sub> and P<sub>L</sub> profiles and higher efficiency with more PV energy directly consumed by the load under dynamic P<sub>P</sub> and P<sub>L</sub> profiles.
IEEE Journal of Solid State Circuits