Adaptive DC-link Voltage Based Bi-Directional Charger for Electric Vehicles

Abstract

This paper proposes an adaptive DC link voltage based bi-directional electric vehicle (EV) charger, which operates in all the four quadrants of P-Q (active-reactive powers) plane. The four quadrants operation of charger enables the, only active (charging/discharging), only reactive (inductive/capacitive) and simultaneous active (charging/discharging) and reactive power (inductive /capacitive) exchange with the grid. This paper also proposes an adaptive DC link voltage strategy for estimating the reference DC link voltage, so that the charger can operate uninterruptedly under all voltage conditions (over voltage and under voltage). The adaptive DC link voltage also helps in minimizing the high-frequency ripple in the grid current. Due to which the total harmonic distortion (THD) of the grid current improves significantly. Because of this, the charger is able to maintain, the supply current THD below 5% in all operating mode. The designed charger operate with 230V, 50Hz single phase supply. The experimental test results captured in both steady state and dynamic conditions, validates the design and control of proposed charger.