Characteristics and Design of an Asymmetrical Duty-Cycle-Controlled LCL-T Resonant Converter

The characteristics of an asymmetrical duty cycle (ADC) controlled LCL-T resonant converter operating at the resonant frequency are studied by solving the state-space model of the converter. Four operating modes are identified having different circuit waveforms representing different device conduction sequences, thereby creating different conditions during the device switching. The mode boundaries are obtained and plotted on the D-Q plane. A region on the D-Q plane is identified for the converter design, where the switches operate under zero-voltage-switching condition. A prototype 500 W, 100 kHz converter is designed and built to experimentally demonstrate the operating modes, control characteristics, and performance of ADC-controlled LCL-T resonant converter.