An integrated charging equalizing converter based on Cuk converter for solar home system

Abstract

A solar home system (SHS), containing three independent parts, namely a load voltage dc–dc converter, an energy storage device (ESD) charger, and an ESD equalizer, will become bulky and costly. Thus, based on Cuk converter, an integrated charging equalizing converter (ICEC) is proposed. The ICEC can achieve load voltage converting, battery/supercapacitor (SC) charging, and equalizing simultaneously. The idea of the ICEC is using a voltage multiplier (VM) to replace the capacitor in Cuk convertor, and then reusing the VM as a charging equalizer. When the Cuk converter is operating, the voltage ripple generated on the VM, which can be regarded as an ac voltage source, is utilized to drive the VM. Therefore, compared with the traditional methods, the charging and equalizing can be achieved without extra switches and magnetic elements. A prototype for four SCs is built to verify the feasibility of the proposed method. And the system efficiency is 87%, corresponding to the input power 5.6 W, the load output power 3.54 W, and the charging balance power 1.33 W. Moreover, a quantitative comparison shows the proposed method can reduce the system size and cost effectively.