Research on An Interleaved Phase-Shift Half-Bridge LLC Resonant Converter

This paper presents the analysis and simulation for a novel high-power density electric vehicle dc-dc converter. In this paper, a novel interleaved phase-shift half-bridge converter that mainly comprises two modules of a half-bridge converter and a double full-bridge rectifier is proposed. In the case of interfacing the high-voltage battery module, the isolated DC/DC converter is used to control the voltage at the input of the battery according to the battery terminal voltage and optimize the efficiency of the dc-dc converter in a wider range of operating voltage. It operates as a voltage doubler to achieve an output voltage of 450V for the charging of a high-voltage battery. The isolated dc-dc converter is operated as an LLC resonant converter owing to its advantages of simple control and soft switching operation. This converter not only has a wide range of zero-voltage-switching (ZVS) turn-on of power switches on the primary side of the transformer but also has a zero-current-switching (ZCS) turn-off of rectifier diode on the secondary side of the transformer. The proposed converter can achieve the output voltage range of 250-450V by adapting the phase shift between the two square waves. The two LLC half-bridge resonant converters are connected in parallel, and it’s operated at a fixed frequency and constant duty cycle. The simplified control strategy in the proposed converter can be achieved since the switching frequency of the converter operates at the resonant point. Finally, a 3.4kW design prototype with 400V input voltage and the 250-450V output voltage is simulated to verify the effectiveness of the phase-shift mode control method.