Mitigation of the effects of common-mode current on the operation of SCR-based rectifiers for AC drives

Common-mode current generated by the PWM AC drive at low modulation index and higher switching frequency results in overheating of the pre-charge resistor of the SCR based rectifier. In this paper, two modifications are proposed for the operation of SCR based rectifiers to significantly reduce the resistor overheating issue. The solution is cost and size effective when compared with alternative solutions. Experimental results are provided to show the reduction of common mode current flow through the pre-charge resistor and the consequent reduction in its temperature.