Operation of fixed frequency Class-D series-parallel resonant converter on utility line with active control

A single-phase high-frequency transformer-isolated Class-D series parallel (LCC type) resonant power converter (SPRC) with fixed frequency is presented. The results of AC analysis are used to design the converter for low harmonic distortion and near unity power factor (PF) operation. The designed converter is studied through simulation (using SABER) and verified experimentally. For reliable operation of the converter at light load and no load conditions a new control logic is used. This control logic with active control is tested experimentally. The experimental results of the 2 kW prototype with active control show that the total harmonic distortion (THD) is less than 5% at full load and less than 22% under light load (i.e 10% of full load) condition with line PF being always greater than 0.95.