POWER FACTOR CORRECTION OF VARIOUS CONVERTERS FOR EV CHARGING APPLICATIONS

Abstract

This work presents the modelling and design of two different EV Chargers. The proposed EV chargers consists of two-stage power conversion. Initially, DBR (Diode Bridge Rectifier) is connected for AC-DC Conversion which is followed by LC Filter to damp out the third order harmonics. The first stage consists of Power factor correction circuit using various DC-DC converters like boost, buck and buck-boost derived converter and the second stage consist of DC-DC stage for providing isolation of the grid and the charging port. Total research is done into two sections as mentioned below. The first section consists of power factor correction using SI-SEPIC Converter cascaded with Flyback converter. It comprises of two stage EV Charger where initial stage consists of SI SEPIC converter, which inherently provides the power factor correction of the EV charger at the source, and the later consists of Flyback converter. Collective combination of these two converters for the EV charger results for the operation of converter at reduced duty ratio resulting which efficiency of the converter is increased. This work mainly focuses on designing the components of the converter and power factor correction using PWM and SPWM controller techniques in MATLAB environment. The SEPIC Converter has a disadvantage of having more ripple in the output current so, modified Zeta converter is used which provides better dynamic response in DCM and it also provides less ripple in the output current. The second section comprises of power factor correction using modified zeta converter cascaded with HB-LLC Resonant Converter. The Modified Zeta Converter operates in Discontinuous Conduction mode (DCM) and LLC Resonant Converter is used to transfer the DC-Link power to the battery. Collective combination of these two converters for the EV charger results in smooth operation, reduced voltage stress across the PFC devices and Modified efficiency of the converters. This work mainly focuses on designing the components of the converter and comparison of the Modified and Conventional Zeta Converter fed HB-LLC Resonant Converter in MATLAB/Simulink environment.