A synchronous rectification using a digital PLL technique for contactless power supplies

A contactless power supply system with a synchronous rectifier using a digital phase-locked loop (PLL) technique is proposed. This technique gives appropriate turnoff timing and prevents the system from shoot through conditions. We used a resonant capacitor and an inductor in the rectifier circuit. These devices are huge and occupied most space of the rectifier unit. Using the digital PLL technique eliminates these devices and miniaturized the rectifier unit to be mounted on the back of the secondary coil. The system achieved 92% maximum direct current-direct current efficiency at 5-mm gap.