Single-switch-regulated resonant WPT receiver

A single-switch-regulated wireless power transfer receiver is presented in this letter. Aiming at low-cost applications, the system involves only a single-switch class-E resonant rectifier, a frequency synchronization circuit, and a microcontroller. The number of power semiconductor devices required in this circuit is minimal. Only one active switch is used and no diode is required. As a single-switch solution, this simplifies circuit implementation, improves reliability, and lowers the hardware cost. The single-switch resonant rectifier provides a relatively constant quasi-sinusoidal voltage waveform to pick up the wireless power from the receiver coil. Due to the resonant nature of the rectifier, zero-voltage-switching (ZVS) turn on and turn off are achieved. The steady-state analysis and discussions on the component sizing and the control design are provided. A prototype is built and experimental works are performed to verify the features: achieving 93% efficiency single-switch ac-dc rectification (85% including the auxiliary circuit), -7.17-dB total-harmonic-distortion ac voltage waveform, ZVS turn on and turn off over wide load range, 0.4% output voltage regulation error, 79% cost reduction as compared with the Qi- compliant receivers, 2.5% overshoot/undershoot after load disturbances, and 1% overshoot after line disturbance.