GB1160803A - Controlled Rectifier Inverter Circuits - Google Patents

Abstract

1,160,803. Cyclical chopping circuits; inverters. LANDIS & GYR A.G. 13 March, 1967 [23 March, 1966], No.11701/67. Headings H2F and H2H. Thyristors 5, 6 connected to an oscillatory load 1 are prevented from being conductive simultaneously by a pulse blocking circuit. The load is energized from a D.C. source through thyristor 5 and on the reverse current swing, current passes through a diode 8 hence extinguishing thyristor 5 and saturating a transductor through a winding 57 allowing pulses from a generator 7 to pass to the gate of thyristor 6 which fires and shunts the load. The second reverse swing of the current passes through a diode 9 thus extinguishing thyristor 6. More than one pulse may be applied to thyristor 6 which may be connected to a similar circuit (not shown) to prevent firing of the thyristor 5. Resistance 5 may be replaced by a current transformer and the transductor by an AND circuit (see Fig. 1, not shown). The pulse generator may comprise a sinusoidal A.F. generator switching on alternate half-cycles impulse switches (32), (33), Fig. 4 (not shown), through differentiating networks (37), (38). Each time the switch (32) is closed pulses are admitted from a generator (41) to thyristor 5 and when switch (33) and another switch (35) are closed pulses are admitted to thyristor 6. If the load is not sufficiently oscillatory, a coupling filter may be added.