A Power Quality Enhanced Push-Pull Converter-Based Two-Stage Onboard Charger for Electric Vehicle Applications

This paper presents an efficient two-stage onboard charger (OBC) using AC-DC converters with improved power quality for electric vehicle (EV) applications. The first stage comprises a diode bridge rectifier (DBR) without an input AC filter and a front-end boost converter (FBC) as a power factor correction (PFC) circuit, stabilizing the output voltage for efficient power transfer. The boost inductor current control is facilitated using a phase-locked loop to achieve input current wave shaping. This FBC drives the second-stage back-end push-pull converter (BPPC) operating in buck mode to ensure the battery is charging in constant current (CC) control mode. The push-pull converter demands its inductor current to be continuous due to the CC mode of battery charging. A detailed analysis of the power converters is conducted through simulations performed using the MathWorks SIMULINK software. Furthermore, a scaled-down hardware prototype has been developed, utilizing a dSPACE 1202 controller, to evaluate the effectiveness of the charger for a 48 V, 100 Ah battery. The test results demonstrate satisfactory performance and compliance with the IEC 61000-3-2 standard. This design effectively maintains input AC power quality during battery charging, highlighting its potential for enhancing EV charging infrastructure.