Method of reducing computation in the analysis of PWM current-source GTO convertor

A method of reducing the computation in the analysis of a pulse width-modulated current-source convertor, employing gate turn-off thyristors, is presented. It is observed that sinusoidal supply currents are obtained by pulse-width modulation (PWM) and are modified by the action of supply-filter elements. The AC quantities can be transformed to DC quantities by using the synchronously rotating reference frames to predict steady-state and transient behaviour without a complete simulation. To demonstrate the usefulness of this approximate method, the predicted steady-state and transient waveforms are compared with experimental and rigorously simulated results. In addition, the typical input and output characteristics of a convertor with phase angle control are shown to illustrate the influences of supply-filter elements