A Low‐Voltage‐Stress Class Φ 2 Converter With Load‐Independent ZVS and Constant‐Voltage Output for MHz WPT Systems

For wireless power transfer (WPT) systems operating in the multi‐MHz range, this paper proposes a three‐level Class converter featuring a coupled T‐type network, alongside a comprehensive parameter design methodology. This proposed method jointly ensures load‐independent low voltage stress, full‐range zero‐voltage switching (ZVS), and a stable constant‐voltage mode (CVM). First, time‐domain modeling is conducted to comprehensively analyze the constraint conditions for load‐independent operation of the topology. Second, the DC‐feed inductor of the proposed topology is innovatively integrated with planar magnetic coupled windings, reducing the inductor current ripple by up to 50%. For practical WPT applications, the coupled inductors of the T‐type network can be integrated into the transmitter coil using a bipolar winding structure to realize effective electromagnetic decoupling. To validate the theoretical analysis, a 3 MHz WPT system prototype based on LCC/S compensation was constructed. Experimental results demonstrate that the proposed circuit topology maintains ZVS and CVM operation across the full power range, with switch voltage stress consistently kept at 1.05 V DC and output voltage fluctuation within 5.2%. The proposed inverter achieves a peak efficiency of 96.3%.