Theoretical Analysis and Designing a Dual-Bridge LLC Resonant Converter for On-Board Charger

Abstract

This paper proposes a unidirectional DC/DC converter architecture based on dual-bridge LLC (DBLLC) resonant converter for on-board charge (OBC) application. The LLC resonant converters are the preferred choice to select of DC/DC converter topology for OBC due to it provides many advantages such as high efficiency, high power density. The conventional LLC resonant converters work at fix duty cycle and variable frequency control. In this paper, a converter based on the dual-bridge LLC resonant converter operating at fixed frequency with the pulse width-modulated (PWM) control will be applied as an isolated stage in the OBC 7.4 kW to improve the power density and to reduce conduction losses. The advantage of operating at the resonant frequency is the switching losses are reduced since the soft-switching technique is achieved over the full load range. Furthermore, the detailed design procedure of a transformer is presented along with the transformer losses and also the switching losses analysis. The proposed topology is designed for 400 VDC input to 220-380VDC output conversion, operating at 100 kHz and in the range from 4.8 kW to 7.4kW. All theoretical analyses and the simulated results on the proposed converter are provided to verify the system performance.