A unity power factor three phase PWM SCR rectifier for high power applications in the metal industry

A new thyristor current source rectifier that achieves unity power factor, low current THD and DC bus current and voltage control is presented. The rectifier is suitable for high power applications such as induction heating and DC arc furnaces. It combines a traditional six-pulse thyristor bridge and a DC chopper that together solve power quality problems such as poor power factor and flicker generation. This topology achieves low input current THD and DC power control without additional power factor correction equipment, harmonic trap filters, use of multiple pulse rectifiers, or high K-factor transformers.