Research on two-stage on-board DC-DC converter and control technology

A two-stage on-board DC-DC converter with a wide input voltage range and output low voltage large current is proposed in this paper. The on-board DC-DC converter consists of a front-stage buck converter and a rear-stage three-phase interleaved LLC resonant converter. The equivalent model is established by the fundamental wave analysis method, and the voltage gain characteristics and current sharing characteristics are analysed. The front-stage converter uses three closed-loop controls to convert a wide range of input voltage to a stable voltage value to the rear-stage. The rear-stage converter adopts phase shift current sharing control to ensure the current balance of each phase and reduce the output current ripple. The system model is established by using the simulation software. The simulation results verify the correctness of the theoretical analysis and the feasibility of the control strategy.