Multiphase solid state cct. frequency changer - uses thyristor groups to control each phase of power line

摘要

Two thyristor groups for each phase unit are connected in parallel opposition across input phases. Output pulse shapers control the thyristors via their respective trigger electrodes, and a zero current state detector comprises, for each thyristor, a bistable unit connected to inputs of an AND gate. The two state-setting inputs of each bistable unit are connected across the output of a pulse transformer whose midpoint is earthed. The transformer has two input windings one connected in series between the control electrode and one pulse shaper and the other connected through a diode and a resistor across the thyristor.