基于定子绕组等效灌注直流的电机转子故障诊断

Fault Diagnosis for Induction Motors Based on Injecting a DC Signal

提出了基于向定子某相等效灌直流的感应电机转子故障诊断新方法。该方法通过一种简单的电路装置等效地向定子绕组灌注一个直流信号。当电机转子故障时,定子电流中将会出现f=2(1-s)fs(s为转差率,fs为电网频率)故障特征频率分量。以三相基波正序电压及其希尔波特变换构造PQ变换矩阵,用其对定子三相电流进行变换,得到有功功率P和无功功率Q。由于正常电机P、Q均恒定,在PQ坐标系下对应一个点;故障电机则由于P、Q中附加频率为f′=(1-2s)fs的波动分量而对应于一个椭圆。通过比较电机正常及转子断条故障运行时P、Q在PQ坐标系下对应的模式,实现转子断条故障的可靠检测。

A new technique for testing rotor faults in induction motors is proposed in this paper. A small device is developed for injecting a small dc signal into line-connected induction machines for diagnosis of rotor faults. If there is a fault in the rotor, there will be conspicuous frequency component at f=2（ 1 -s）fs Hz which could be picked up by the stator winding. With the positive sequence fundamental voltage components and its minus Hilbert transformation as elements, a PQ transformation matrix is constructed. The active power P and reactive power Q can be obtained through the PQ transformation of the stator currents. Due to the P and Q are both constants for healthy motor, they correspond to a dot on the reference coordinate. And the P and Q of the rotor broken bar motor will correspond to an ellipse because they comprise an additional frequency of f = （1 -2s）fs （s is the slip and fs is supply frequency）. By distinguishing of these two different patterns, the rotor broken bar fault can be detected.