| 摘要 |
PURPOSE:To reduce a starting current by applying a voltage having a low frequency and a low voltage level to preliminarily excite it, confirming that a current falls within the optimum set value range and then increasing the frequency and the voltage level as time goes. CONSTITUTION:A controller 4 controls an inverter 2 to supply a low voltage having a low frequency to a synchronous motor 3 to preliminarily excite it at the starting time. If the fact that a current detected by a current transformer CT arrives at the set current within I0+ or -DELTAI0 is detected, the voltage level is abruptly increased. After the prescribed time, if the fact that the current falls within the range of the set current I0+ or -DELTAI0 is detected, it is judged that synchronous rotation is stably performed to lineary increase the frequency and the voltage. Thus, the starting current can be decreased, and the starting capacity of an inverter can be reduced. |
