A high-frequency off-line SMR converter with improved performance characteristics

A novel offline high-frequency switch-mode rectifier (SMR) converter topology is presented. This topology allows the safe use of lossless single-capacitor switch snubbers from zero to rated load power variation. To ensure the safe and lossless operation of the high-frequency stage under all operating conditions, the inverter stage is analyzed in detail and expressions are derived for the snubber capacitor voltage as a function of the high-frequency transformer leakage and magnetizing inductances, operating frequency, and the charging time of the snubber capacitors. The effect of AC source voltage fluctuations on the input power factor is also analyzed for the front-end half-controlled bridge rectifier. The theoretical results have been verified experimentally