Low-Overhead Maximum Power Point Tracking for Micro-Scale Solar Energy Harvesting Systems

Abstract

Environmental energy harvesting is a promising approach to achieving extremely long operational lifetimes in a variety of micro-scale electronic systems. Maximum power point tracking (MPPT) is a technique used in energy harvesting systems to maximize the amount of harvested power. Existing MPPT methods, originally intended for large-scale systems, incur high power overheads when used in micro-scale energy harvesting, where the output voltage of the transducers is very low (less than 500mV) and the harvested power is miniscule (only hundreds of µW). This paper presents a low-overhead MPPT algorithm for micro-scale solar energy harvesting systems. The proposed algorithm is based on the use of a negative feedback control loop and is particularly amenable to hardware-efficient implementation. We have used the proposed algorithm to design a micro-scale solar energy harvesting system, which has been implemented using IBM 45nm technology. Post-layout simulation results demonstrate that the proposed MPPT scheme successfully tracks the optimal operating point with a tracking error of less than 1% and incurs minimal power overheads.