This paper proposes the controller design for a stability improvement of an on-board battery charger. The system is comprised of a
power factor correction (PFC) circuit and phase shift full-bridge DC-DC converter. The PFC circuit performs the control of the DC-link
voltage and the input power factor. The DC-DC converter regulates the voltage and the current in the battery using the DC-link
voltage. This paper proposes the design method of PI controller for the PFC circuit using a small signal model. The analysis and
design of a type-three controller for the DC-DC converter is also presented. A simulation and experiment has been performed on
the on-board battery charger and their results are presented to verify the validity of the proposed system.