This article investigates zero-voltage switching (ZVS) of a secondary-side active rectifier in an LCCL–LCCL compensated wireless power transfer (WPT) system subject to variations in magnetic coupling. Since changes in coupling affect the power transferred through the resonant network, output power regulation is carried out on the secondary side by adjusting the rectifier phase offset ϕps relative to the primary. This phase shift alters the effective tank impedance seen by the rectifier and therefore directly impacts the achievable ZVS operating range. A state-plane formulation yields a closed-form expression for the minimum dead time required for ZVS. For effective analysis, the fast resonant dynamics that govern ZVS are isolated from the slower tank dynamics by simplifying the circuit using state- variable analysis. The ZVS boundary is characterized in terms of coupling factor k and phase shift ϕps, and validated in PLECs. Finally, hardware results are presented at an output power of 30 kW using an 85 kHz WPT prototype.
