| 摘要 |
<p>An inverter for supplying alternating current to a load from a direct current supply including a thyristor bridge for selectively connecting each AC terminal of the load to either the positive or the negative terminal of the direct current supply through respective inductors, or parts thereof. A freewheel diode bridge is also provided for returning energy induced by the load to the power supply. A commutation circuit, including a commutation capacitor is arranged for inducing thyristor turn-off voltage pulses in the inductors. The components are arranged, or means are provided, for reducing the voltage rating of the thyristors. Thus the connection of the commutation circuit to the inductors is such that the commutation capacitor voltage is applied across a different number of turns in various periods of the duration of the voltage pulse; the inductors may each have a second winding connected between an end of the freewheel diode bridge and the supply terminal opposite to that to which the first winding is connected; the commutation capacitor may be arranged never to be connected directly across the supply terminals, an auxiliary DC supply being provided for charging up and maintaining the voltage across the capacitor; the commutation capacitor may comprise two capacitors which are arranged in series between the supply terminals, the interconnection between these capacitors being selectively connectable to the inductors for generating the turn-off voltage pulse.</p> |
