Single-stage isolated bridgeless PFC converter achieves 98% efficiency

The single-stage isolated bridgeless PFC Converter with pulsating input current attains improved efficiency of over 98% compared to 89% of the Three-stage approach, offering simultaneously significant size and cost reductions, while maintaining the near unity power factor of 0.999 and 1.7% total harmonic distortion. A very clear objective to increase the efficiency is to devise a converter, which can eliminate a front-end full-bridge rectifier. Past attempts failed to eliminate diode-bridge rectifiers, leading to the belief that the solution to such a goal may be impossible and that such converter topology could not exist. The current rectifier CR2 also responds automatically to the state of the switch S and polarity of the input ac voltage. For the positive polarity it conducts during the OFF-time interval of switch S and for negative polarity, it conducts during the ON-time interval of switch S.