DN-63 The Current-Doubler Rectifier: An Alternative Rectification Technique

The UC3875, UC3879, and UC3895 families of ICs control a bridge power stage by phase-shifting the switching of one half-bridge with respect to the other. This method allows constant-frequency pulse-width modulation in combination with resonant, zero-voltage switching for high efficiency performance. These ICs can be configured to provide control in either voltage mode or current mode operation, with overcurrent shutdown for fast fault-protection. This design note describes an alternative rectification method that offers simpler structure and better use of the isolation transformers in push-pull, half-bridge and bridge power stages, where full-wave rectification is usually required, on the secondary side of the transformers. Converters using the current-doubler rectifier can achieve lower and better distributed power dissipation and smaller size in the magnetic components.