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
Ryota Kondo, Yusuke Higaki, Masaki Yamada
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 loads. 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 reactive current, which increases the power loss under light loads. The phase shift amount 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 loads (240W), compared with the conventional control.