Multi-Coil Pad Driving Algorithm Based on Phase Coupling Coefficient for High Efficiency Operation of 50 kW Wireless Power Transfer System for Electric Vehicles

This paper proposes an optimal driving algorithm for 50 [kW] wireless charging system with multi-coil pad to achieve high efficiency over a wide load range under SAE J2954 misalignment. Two driving strategies are considered, simultaneous driving where all phases are activated and selective driving where only well-coupled phases are activated. The target system employs a three-phase pad composed of DDP coils for phases A and B and a CP coil for phase C, together with a three-phase IPT converter that supports phase selection. Based on loss characteristics under varying load and alignment conditions, the multi-coil driving algorithm is derived to switch between the two strategies and to select the active A/B phase during selective operation. Finally proposed multi-coil driving algorithm is validated the feasibility and efficiency improvement through experiments on a 50 [kW] system.