| 摘要 |
PURPOSE: To realize an efficient operation by a constitution wherein only one converter is operated at the time of powering and when the current of an invertor reaches a predetermined level, the operation is stopped and the other converter is started to drive an invertor. CONSTITUTION: When a converter 31 and a chopper are started, a converter 31 performs DC voltage control and a chopper performs current control of the converter 31 which is operated with 10% current. An invertor then starts the powering operation and the current of the chopper decreases depending on the load current. When the load current reaches 10% of rated value, the current of the chopper goes zero and a stop command is delivered from a converter coordination monitor. When the load current reaches 20% of rated value, a hysteresis comparator 25 delivers a start signal and upon starting a converter 3, a two group operating state signal of converter is delivered to the current balance circuit of the converter 3, 31. Consequently, a switch is turned to the second gain circuit side thus realizing an efficient operation. |
