【作者】 刘玲；

【导师】 黄进；

【作者基本信息】 浙江大学 ， 电气工程， 2007， 硕士

【摘要】 电机故障不仅会损坏电机本身，严重时还会使电机突然停机、生产线崩溃，造成巨大的经济损失和灾难性后果。历史数据表明，转子断条是感应电机最常见的故障，占其全部故障种类的10％左右。因此，研究转子故障诊断技术以便在电机故障早期发现故障并及时进行维修，具有重大的理论意义和社会经济效益。本文先讲述向定子绕组灌注直流的基本原理，然后分别论证了两次PQ变换法及扩展Park矢量法测转子断条故障的可行性。等效直流灌注法并非真实地向绕组内部注入直流电流，而是通过串联在电机供电回路的一种简单电路装置，通过改变一个工频周期内此装置两端的阻抗，等效为向定子绕组中注入了一个直流分量。在DIM（直流灌注模式）下，当电机转子断条故障时，定子电流中会附加一个远离基频的故障特征频率f_1g=2（1-s）f_s（s为电机的转差率，f_s为电源基波频率），实验结果论证了上述理论推导的正确性。基于电网电压基波正序分量及其Hilbert变换构造了坐标变换矩阵，定义了PQ变换的概念，提出了在DIM模式（直流灌注模式）下，基于两次PQ变换的转子故障诊断方法的原理。实验结果论证了该方法的可行性。本文还介绍了一种基于对定子电流Park矢量模进行频谱分析的电机转子故障诊断方法。该方法结合了传统的定子电流频谱分析法和Park矢量图形识别法进行电机转子故障诊断的的优点。实验结果验证了该方法的可行性与有效性。更多还原

【Abstract】 A motor failure not only can result in damage to the motor, but also can result in unscheduled machine downtime and the shutdown of a production line, which will cause heavy financial losses and catastrophic failure. Statistical studies have shown that the rotor broken bar fault, which account for nearly 10% of total induction motor failures, is the most familiar fault for induction motors. Consequently, researches on rotor broken bar fault diagnosis able to detect this kind of fault at an early stage and also to allow for carefully planed repair actions are of great theoretical significance and socioeconomic benefits. Firstly, the principle of injecting a small DC signal into line-connected induction machines for diagnosis of rotor faults is proposed in this paper. Then, the feasibility and validity of testing rotor broken bar fault based on twice PQ transformation and Extended Park’s Vector Approach is verified.The equivalent DC injection is not actually injecting a dc bias into the stator winding, but causing the voltage drop across the circuit to be asymmetrical by means of the asymmetrical resistance in a period. Under DIM (DC Injection Mode) , when there is a fault in the rotor, therewill be conspicuous frequency component at 2(1-s)f_s Hz which is far away from the main frequency in the spectrum. The main task of this paper is to detect the rotor broken bar fault by means of extracting and describing the conspicuous frequency component at 2(1-s)f_s Hzquantificationally.With the positive sequence fundamental voltage components and its minus Hilbert transformation as elements, the new PQ transformation matrix is constructed and the rotor broken bar fault diagnosis method based on the twice PQ transformation is presented. And the results obtained from laboratory size motors demonstrate the effectiveness of the proposed technique, for detecting broken rotor bars in operating three-phase induction machines.This paper also introduces another new approach, based on the spectral analysis of the motor current Park’s Vector modulus, for detecting the occurrence of rotor cage faults in operating three-phase induction machines. The major theoretical principles of the Extended Park’s Vector Approach are described. Laboratory test results demonstrate how the presence of rotor cage faults can be effectively detected by the application of this new approach.. These results are also correlated with the ones obtained by the conventional motor current spectral analysis and by the classic Park’s Vector Approach.更多还原