A three-phase AC-DC GTO thyristor converter employing equal pulse width modulation (EPWM) (for DC motor control)

A comparative study of equal, triangular, stepped, sinusoidal, and inverted sinusoidal pulse-width modulation (PWM) schemes on source and load performances of a three-phase AC-DC GTO thyristor converter-fed DC motor is presented. The two-quadrant GTO thyristor converter is studied in detail using an equal PWM (EPWM) scheme. A symmetrical gate pulse pattern that reduces the number of switchings and allows switching GTOs an equal number of times in each supply cycle is reported. Smooth and continuous transition is obtained between rectification and inversion with a single GTO converter. The proposed converter was designed, constructed, and tested using a 3 hp laboratory-sized separately excited DC motor. The experimental results are shown to be in good agreement with the theory.<
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