| 摘要 |
A-C energy, from an a-c power system, is converted by a phase-controlled SCR rectifier bridge, which is followed by a series-connected filter choke and a shunt-connected filter capacitor, to d-c power for delivery via a d-c bus to a load, such as an inverter and an a-c induction motor driven by the inverter. When there is a decrease in load demand, for example when the motor speed is to be reduced, fast speed control is obtained by regenerating power back into the a-c power system from the load. Power flow through the d-c power supply is reversed by means of a switching network, interposed between the filter choke and capacitor, having a pair of reverse SCR's for cross-coupling the positive and negative lines of the d-c bus. When the reverse SCR's are fired into conduction, the connections between the filter capacitor and the bridge's output terminals are effectively reversed, thereby facilitating power flow from the load to the a-c power system.
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