Starting manner null of synchronous motor for invar - ta Drive

摘要

PURPOSE:To reduce a starting current by applying a pulse having a low frequency and a low voltage level to preliminarily excite it, and then increasing the frequency and the voltage level when pulling in synchronization. CONSTITUTION:A controller 4 controls an inverter 2 to supply a low voltage having a low frequency to a synchronous motor 3 at the starting time. A frequency comparator S1 and a voltage comparator S2 apply a control signal to the controller 4 so that the frequency and the voltage become set values F1, V1. If the detection current of a current transformer CT becomes the set current value I1 or lower capable of confirming the pull-in in synchronization in this state, the controller 4 linearly increases the frequency and the voltage. Thus, the starting current can be decreased, and the starting capacity of an inverter can be reduced.