异步电动机转子相感抗X_(20)计算方法分析

Analysis of computing method of rotor phase inductance X_(20) of induction motor

针对异步电动机转子相电阻r2容易测量,而转子相感抗X20不易测得,且尚无计算X20关系式的现状,以电工理论为基础,定义电机最大转矩Tm和起动转矩Tst的比值为启动系数λst,分析得出了用转子相电阻r2和启动系数λst计算X20的公式。在额定条件下,异步电动机的Tm和Tst是恒定的,λst是易于得出的常数,因而在已知转子相电阻r2的条件下,利用该公式即可方便地计算转子相感抗X20,并可由X20的计算公式进一步得出电动机临界转差率sm的计算公式。

The rotor phase resistance r2 of induction motor is quite easily measured, but the measurement of rotor phase inductance X20 is not so easy, there is no relation formula to compute X20, either. Based on the electro-technology theory, this study defines the ratio of maximum torque Tm to starting torque Tst as the starting modulus λst, and reaches a conclusion that X20 can be calculated by using the rotor phase resistance r2 and the starting modulus λst. For whichever induction motor, on rated conditions its maximum torque Tm and starting torque Tst are invariable,and λst is an easy educible constant. Therefore,under the condition of knowing rotor phase resistance r2 ,it＇s due to the function relation that it＇s possible to calculate the rotor phase inductance X20 more conveniently, moreover, the calculating formula of the critical slip sm is established thereafter.