Vehicle to grid and grid to vehicle bidirectional power flow at unity power factor with DC ripple compensation

Abstract

In this paper, a single-phase AC-DC converter is proposed with an auxiliary circuit for DC ripple compensation and a DC-DC converter for bidirectional power flow between PHEV (Plug in Hybrid Electric Vehicle) and power grid. There is an existence of second-order harmonic ripple voltage on the DC bus of single phase PWM voltage source converter (VSC). The low frequency ripple voltages normally filtered using a bulk capacitor at the DC bus which results in low power density and require large space. An auxiliary circuit for DC ripple compensation reduces the size of DC link capacitor. The overall converter configuration, with bidirectional power flow regulates unity power factor at the grid. In first stage, a 230 V 50 Hz AC supply is converted in to 400 V DC with ripple compensation using a single-phase VSC and in the second stage, the charging and discharging of the PHEV battery is monitor through a buck boost DC-DC converter. Buck mode is used for charging and boost mode is used for discharging. In case of discharging, energy sent back to the grid at 230V, 50 Hz. A battery rating of 1.8 kW at 120V is used in PHEV.