摘要：研究了三相交流异步电动机分级变频起动的起动方法，并分析了电机在软起动调压过程中产生电流振荡的原因。提出了在电机分级变频软起动器控制系统中应实施电动机功率因数角闭环控制的观点，通过分析指出：晶闸管调压电路中可控的晶闸管触发角应该由两部分组成，一部分是按预定规律调整的角度，另一部分是跟随电机功率因数角的变化而增加的动态调整角度。该方法可以使电动机起动过程中的电磁转矩和电流脉动得到明显的抑制。

关键词：三相交流异步电动机；分级变频；功率因数角；晶闸管
Abstract: The starting method of discrete frequency softstarter for three-phase alternating current asynchronous motor was studied in this paper, and the cause of phase current oscillation during soft starting was analyzed. It was proposed that the displacement angle closed loop control was introduced in discrete frequency softstarter for three-phase alternating current asynchronous motor. Through analyzing, pointed out that the thyristor firing angle should be composed of two parts. One is obtained from the predetermined voltage control rule, and the other is the increase of dynamic regulating angle with the variation of displacement angle. The fluctuation of current and the electromagnetic torque can be restrained obviously with this method.

Key words: three-phase alternating current asynchronous motor; discrete frequency softstarter; power factor angle; thyristor