A Modified Luo Converter-Based Electric Vehicle Battery Charger With Power Quality Improvement

Abstract

Most of the single-stage single switch power factor correction (PFC) solutions have limited applications in high power ac–dc converters as an increased voltage across and current through the semiconductor devices are seen, which, in turn, results into lower efficiency. This article deals with a modified isolated Luo PFC converter-based electric vehicle (EV) charger with two switches and input clamping diodes at the primary of an isolation high frequency transformer (HFT). This configuration facilitates the advantage of comparatively low switch voltage stress, which is clamped at the input voltage. The proposed converter is selected to operate in discontinuous conduction mode (DCM) to obtain built-in PF correction capability at ac mains. The operation of the converter in DCM, considerably reduces the control complexity due to reduced number of sensors. A prototype is implemented to verify the improved power quality (PQ) performance of the proposed modified Luo converter. An improved low ripple-based charging is provided in constant current-constant voltage modes, which improve the long-term battery service life. The performance of the converter is found robust enough to validate the efficacy of charging at steady state and at varying line voltage variation range. The improved PQ indices are observed to meet the international standards of IEC 61000-3-2.