An Efficient PV Battery Charger/Harvester for Low Power Applications, Suitable for Heavily Overcast Operations

Abstract

A DC-DC boost converter is a vital part of any power harvesting system. Coupled inductors have been utilized to increase and extend the voltage gain of the boost converter. Although the duty cycle impedance matching method can accommodate the efficiency regulation in a boost converter, it suffers from voltage loss during shading. This paper introduces a modified interleaved coupled boost converter Photo-Voltaic (PV) for low power applications with increased voltage gain to solve this issue. The proposed approach facilitates the operating condition of the power harvesting during a heavy overcast by improving the efficiency and output voltage. It responds to a wider range of solar irradiations and extends the solar operational range of the charger/harvester with an improved output current, reliability, and functionality in Continuous Current Mode (CCM). A prototype has been implemented and successfully tested to verify and validate the proposed topology. An efficiency of 87.4% is retained for the harvester during an overcast.

Keywords

• Battery charger
• boost converter
• coupled inductor
• impedance match
• low power harvest
• photo voltaic