电机离心开关断开瞬时转速测量仪

Transient Rotate Speed Meter of Motor for the Centrifugal Switch's Breaking Away

离心开关断开转速是单相电动机的一个关键技术指标。由于电动机的起动过程很短,一般中小型电动机的起动时间都在1～3s内,所以在离心开关断开前后,电机转速变化很快。测量的难点是:(1)获得离心开关断开瞬时,既无时延又无稳定的信号;(2)准确的瞬时转速测量方法。该测量仪采用单片机为核心器件,当电机起动时,直接监测离心开关两端的电压来得到离心开关断开的瞬时信号;同时使用光电旋转编码器获取电机瞬时转动脉冲信号,经过光耦隔离后送单片机,测量电机瞬时转速。

The rotate speed is a key performance of single-phase motors while the centrifugal switch is breaking away.Because a motor start quickly,such as the start time of ordinary middle and small motors is between 1 and 3 seconds,the change of its rotate speed is very fast while the centrifugal switch is breaking away.There are two difficulty problems:(1)how to capture a no-delay and steady signal at that instant time;(2)a accurate method of measuring transient rotate speed.In this meter a micro-controller is used as a core.When a motor is starting,the voltage of both ends of centrifugal switch is detected to capture the signal of breaking away;a pulse signal from a photo-electricity rotate coder is taken along with the motor's rotating,then the signal is insulated by photic-coupling and transmitted to the micro-controller for measuring transient rotate speed.