A New Constant Extinction Angle Control for AC/DC/AC Static Convertors

Maximum utilization of an invertor´s capacity and minimum consumption of reactive power demands an accurate constant extinction angle control. A new scheme for such a control is presented that is based on the integration of each commutating voltage waveform from -ß+ ¿c, thereby obtaining a simulation of the steady- state commutation equation. The resulting control is capable of fresh computation of the firing angle every cycle. The control is extended to cover the convertor operation over its full range from a minimum permissible angle of delay to the minimum permissible extinction angle.