The Study Of Speed Measurement And Faults Diagnosis Of Induction Motor

With the rapid development of AC power system and the continuous improvement of motor manufacturing technology,induction motor has been widely used in agricultural production,industrial production and other fields.Carrying out motor performance parameter detection and real-time fault monitoring and diagnosis which take motor speed as main content is very important to the safe operation of motor.This paper which used the motor stator current analysis method to study the speed measurement and faults diagnosis,combined with the current signal theory of the previous processing,has proposed an efficient current signal processing algorithm.By using Hilbert transform and the self multiplying transform,frequency shift of the acquired digital signal was accomplished,and the signal frequency spectrum could be obtained by using Fourier transform algorithm for multi window complex modulation to the self multiplied discrete data which finished the work of spectral subdivision.According to the pole number and rotor fault characteristic frequency,the frequency spectrum could be processed,and the motor speed could be calculated and the motor faulty state could be judged.On the basis of the above,the speed measurement and faults diagnosis of induction motor apparatus has been made.The tester took the STM32F407 microprocessor as the core,and the current signal of the motor was induced by the current sensor.The signal firstly triggered capture interrupt after signal normalization and filtering,so the signal fundamental frequency can be acquired.Then the 16 bit digital converter,which was controlled by digital frequency multiplication method,carried out the whole cycle sampling.After sampling data processing was completed,the results were displayed on the TFT interface.The test instrument and PC can communicate through the RS232 interface,and they can transmit data on the basis of corresponding communication protocol.PC judged the data type after received the data.If it's the result that has been processed by testing instrument,it would be saved in the SQL database;if it's the original sampling data,the spectrum analysis with higher resolution would be done.Finally,using asynchronous motor as the experiment object,the speed measurement of the prototype and the rotor fault diagnosis experiment was carried out.The experimental results show that the measuring system can accurately measure the motor speed,and the maximum speed error is 4rpm,and rotor fault judgment error rate is low.