Characteristics of fixed frequency series-parallel resonant converter operating on the utility line with and without active control

A 1-φ high-frequency transformer isolated AC-to-DC controlled rectifier using a fixed-frequency series-parallel (or LCC type) resonant converter (SPRC) is presented. A simple analysis and design procedure is used for designing the converter for low line current harmonic distortion and high power-factor (PF) operation. The converter performance characterstics have been verified with SPICE simulations and an experimental prototype SPRC, without using active control. These results show that, although no active control is used, the converter operates with a line current total harmonic distortion (THD) of <15% at full load and 23% at 10% load, with line PF >0.975. Active control has also been implemented with the experimental prototype to achieve a line PF >0.99 at full load and a THD of <15%, for the entire load range