A new simultaneous gating GTO dual converter-fed DC motor drive without circulating current

A dual converter comprised of two three-phase AC-DC pulse width-modulated (PWM) gate-turn-off (GTO) thyristor converters is proposed. The gating pulse pattern of the converters is chosen so that no circulating current flows between the converters when they are operated simultaneously. In addition, a good input power factor is obtained with less ripple in the output current. A symmetrical type of grating is worked out in which all the GTOs in the converter are switched an equal number of times during each cycle of the source voltage. The motor current is free to reverse naturally at any moment; hence, the possibility of discontinuous conduction of the motor current is not there. A four-quadrant closed-loop speed-controlled drive fed from the proposed dual converter is designed, constructed, and tested. The experimental results are in good agreement with theory.<>