An Improved PQ Zeta Converter with Reduced Switch Voltage Stress for Electric Vehicle Battery Charger

This work presents an improved Zeta PFC (Power Factor Correction) converter with reduced switch voltage stress on PFC devices for enhanced power quality battery electric vehicle charger (BEV). A flyback converter is cascaded after this improved Zeta PFC converter to control the battery current during charging in CC-CV mode. This Zeta PFC converter is the modified version with two switch and clamping diodes at the input of conventional Zeta converter. The main advantage is seen that the switch voltage stress is reduced to supply voltage, which results into lower losses in PFC stage and, therefore, the efficiency of the charger is improved over chargers based on other Zeta PFC converters. The improved zeta converter as well as a flyback converter is designed in discontinuous conduction mode (DCM). This gives the advantage of reduced cost and size with less sensors in the circuit and low magnetic volume. The prototype for this charger is developed and tested with a 48V/100Ah battery to verify its effectiveness for different line and loading conditions. A comparison is given to show the reduced device stress, improved PQ and efficiency.