Resonance Commutated Thyristor dc Chopper Design Criteria

A procedure is developed for determining optimum values of the LC commutating circuit components in the resonance commutated thyristor dc switch or chopper circuit. Based on an approximate analysis of the circuit by Gutzwiller et al. [1], a more accurate expression is obtained in parametric form and solved graphically. With this solution, values for the series inductor and commutating capacitor can be selected which minimize component size and cost for given values of thyristor turn-off time and peak load current. It is shown that for a given reverse-biasing time, the influence of the value of commutating capacitor on rate of rise of voltage across the thyristor is not pronounced.