Variable Frequency and Dual Phase Shift Segmented Control Strategy of CLLC Resonant Converter for on-Board Charger

The bidirectional CLLC resonant converter is widely used in electric vehicle charging devices because of its symmetrical structure, consistent forward and reverse working characteristics, and good soft switching characteristics. The on-board charger generally adopts a two-stage charging method. The constant current stage needs to meet a wide range of voltage output characteristics, and the constant voltage stage achieves stable and reliable voltage output. To meet the requirements of charging characteristics of CLLC resonant converter, this paper proposes a variable frequency and dual phase shift segmented control strategy. In the constant current charging stage, a wide range of voltage output is realized by variable frequency and dual phase shift segmented control. In the constant voltage charging stage, the variable frequency control maintains a stable and reliable voltage output. The simulation and experimental results show that the proposed control method effectively broadens the output voltage range of the CLLC resonant converter and realizes reliable voltage and current output in the two-stage charging process.