GB1389160A - Voltage regulator - Google Patents

Abstract

1389160 Control of D.C. motors L V VASILIEV and E G BUYANOV 24 Aug 1973 40293/73 Heading H2J [Also in Division H3] A load 5 such as a D.C. motor is supplied with a pulse-width modulated voltage by the circuit shown, a typical operating cycle being as follows: (1) Application of a D.C. supply voltage U charges capacitors 9, 14 through a diode 7 and choke 8 until a firing pulse is applied to a damping thyristor 10, whereupon the capacitor 14 discharges through the load 5 and capacitor 9 is further charged through members 7, 8, 10 and 5 to a voltage exceeding the supply voltage U (up to 2U), completion of charging rendering the thyristor 10 non-conductive. (2) Thyristors 6, 11 are fired simultaneously to pass current through the load 5 and cause the capacitor 9 to recharge to a reverse voltage through chokes 8, 12, the capacitor 14 also being charged through members 7, 11 and 12 to a voltage exceeding the supply voltage U. These recharge and charge operations render the thyristor 11 non-conductive. (3) Thyristor 10 is fired to apply the voltage of capacitors 9, 14 to the thyristor 6 which is thus made non-conductive, whereupon capacitors 9, 14 are respectively charged and discharged as described in (1) above and the circuit is reset ready for further firing of thyristors 6, 11. The described voltage regulator ensures that the capacitors 9, 14 retain their charge during drops in the supply voltage U; that failure to turn off thyristor 6 is followed by charging of capacitors 9, 14 when thyristor 11 is subsequently fired, whereby turn-off of thyristor 6 is again possible; and that the load can be permanently supplied through thyristor 6 by removing the firing pulse supply to thyristors 10, 11 at any moment during regulating operation, after which the latter can be automatically restarted by restoring the firing pulse supply.