Design and control of the phase shift full bridge converter for the on-board battery charger of the electric forklift

This paper describes the design and control of phase shift full bridge converter with a current doubler, which can be used for the on-board charger for the lead acid battery of the electric forklift. Unlike the common resistance load the battery has a large capacitance element and it absorbs the entire converter output ripple current thereby shortening the battery life and degrading the system efficiency. In this paper the phase shift full bridge converter with a current doubler has been adopted to decrease the output ripple current and the transformer rating of the charger. The charge controller is designed by using small signal model of the converter considering the internal impedance of the battery. The stability and performance of the battery charger is then verified by the constant current (CC) and constant voltage (CV) charge experiments using an actual lead-acid battery bank for the electric forklift.