A hybrid resonant converter operated as a low harmonic rectifier with and without active control

A 1-/spl phi/ high-frequency transformer-isolated AC-to-DC-controlled rectifier with low-line-current harmonic distortion using a variable-frequency-controlled hybrid parallel-series resonant converter bridge is proposed. Operation with and without active line-current waveshaping is presented. The state-space analysis method is used to get various design curves and to predict theoretically the waveforms and line-current harmonic distortion. By exercising active current control, power factor (PF) close to unity with low-line-current distortion is maintained for the entire range of operation in addition to zero-voltage switching (ZVS). Simulation results obtained from the state-space model, SPICE3 (without active control), and experimental results (rated at 150 W with and without active control) are given to demonstrate and validate the operating principle and characteristics of the proposed converter.