A Modified-Zeta Converter based Onboard Battery Charging with Improved THD

This paper presents onboard battery charging with a modified Zeta converter. Charging system is incorporated with two clamping diodes and two extra switches at Zeta converter input resulting in low THD input current and better charging efficiency by mitigating the problems of conventional Zeta converter. An AC-DC conversion is employed by diode bridge rectifier (DBR) followed by modified Zeta converter as power factor correction (PFC) unit, and the flyback converter is used to synchronize the current of battery with the implementation of closed loop cascaded PI control during constant voltage (CV) mode and constant current (CC) mode. Zeta converter is operated in Discontinuous conduction mode (DCM) mode such that Zeta converter can work with better dynamic response, and low ripple at the output voltage. Linear PI control topology is employed here, which has cascaded control for the better working efficiency of the charger. Proposed converter operation is to achieve low total harmonic distortion (THD) within IEC 61000-3-2 standards. Due to inbuilt isolation, components are less and hence proving the system to be more reliable. Proposed system’s efficacy is validated in MATLAB SIMULINK.