Novel current injection technique in controlled rectifier

This paper describes a technique to achieve low harmonic and unity power factor for a three-phase controlled rectifier. The proposed controlled rectifier consists of a thyristor bridge, three bidirectional switches, and a current shaping network. The bidirectional switch is switched at double the line frequency. The current shaping network consists of two capacitor and three resistors. The scheme provides a simple upgrading to controlled rectifier based DC drives. THD and power factor improvements are acceptable. The output DC voltage characteristic is similar with capacitor smoothing rectifier. This scheme is suitable for application at medium to high power level DC motor or a front end to AC motor drive.