A Hybrid Three-Port Isolated DC-DC Converter With Topology-Level Power Decoupling for Electric Vehicles

To address the high cost and multiport power coupling inherent in integrated onboard charger and DC power module architectures for electric vehicles, this paper proposes a hybrid three-port isolated DC-DC converter that achieves topology-level power decoupling, enabling independent control of each port. Steady-state power transfer expressions for all ports are derived, providing a quantitative basis for control. By analyzing various modes of the three-port converter, the optimal port placement for the decoupling network is determined. To mitigate overcharging risks of the low-voltage battery, operation-bound parameter design and constraints are introduced. Based on the quantitative mapping between port power and control variables, an independent port power control strategy is developed. Detailed experimental results validate the correctness and feasibility of the proposed topology and power control methodology.