Self-oscillating contactless resonant converter with phase detection contactless current transformer

A secondary winding shorted current transformer (CT), called phase detection contactless current transformer (PDCCT) is proposed to provide passive current phase detection solution for self-oscillating contactless resonant converter (SOCRC). The proposed PDCCT can detect the current phase from the secondary side of a contactless resonant converter (CRC) and feedback to the primary side rapidly and accurately regardless of the variable air gap. To guarantee the operation of SOCRC, the time delay in control circuitry are studied and compensated. Steady state and dynamic state experimental results on a 60W SOCRC with PDCCT show the validity of both the accurate detection of PDCCT and the rapidly response of SOCRC.