An Improved PFC Bridgeless SEPIC Converter for Electric Vehicle Charger

An improved charger for electric vehicle with bridgeless PFC (Power Factor Correction) SEPIC (Single Ended Primary Inductor) converter topology is designed and discussed in this paper, which cascades a flyback converter to control the charging. The main disadvantage of PFC SEPIC converter is the high current stress across the output capacitor as a diode is present at the output. Therefore, these converters are restricted to the low power applications. The proposed converter overcomes the above limitation as the gain of proposed converter is doubled which results into reduced stress across the output capacitors. The voltage stress across the semiconductor device is considerably reduced for the same output voltage level due to high converter gain and lower duty cycle required for proposed converter as compared to conventional converter. The flyback converter controls the charging in constant current (CC) and constant voltage charging (CV) modes. Both the converters are designed to operate in discontinuous mode (DCM), which eliminates the need for input current sensor and inherent zero current switching for the converters is achieved. A prototype is developed and tested to verify the effectiveness of charger to conform the PQ regulations such as IEC 61000-3-2, at steady state and at wide varying source rms voltages.