Experimental Verification of Reducing Power Loss under Light Load Condition of a Bi-Directional Isolated DC/DC Converter for a Battery Charger-Discharger of Electric Vehicle

Abstract

This paper proposes a bi-directional isolated DC/DC converter for the battery charger and discharger of Electric Vehicle to reduce the power loss under light load condition. The proposed DC/DC converter consists of two full-bridge inverters, an isolated transformer, and a boost reactor, and provides bi-directional transmission, buck-boost conversion, zero - voltage - switching and reactive power suppression. Two power semiconductors of the inverter in the rectification side are turned off to block a reverse current, which increases the power loss under light load condition. The amount of phase shift in the two full bridge inverters are controlled continuously and simultaneously seamless power transmission. The 400V-3.5kW experimental system exhibits stable bi-directional buck-boost conversion and seamless transition between the charging and discharging modes, while suppressing the reactive power. Moreover, the proposed DC/DC converter reduces power loss by 67.5W under light load (240W) condition, compared with the conventional control.