Research On Bearing Fault Diagnosis System For Marine Induction Motor

At present, the induction motor has been applied widely on vessel, owing to its high reliability, simple structure and low cost. Once motor has faults, propelling system and power system stop possibly. Then it will threat the security of marine navigation. Bearing fault has the highest probability in all faults of motor. So this paper researches the bearing fault diagnosis system for marine induction motor.The main content of this paper is confirming the diagnostic method of bearing fault, researching how to pick up the character of bearing fault and making up of the on-line diagnosis system of bearing fault for marine induction motor.Through analyzing existing method of fault diagnosis, and considering the especial operation condition on vessel and the character of bearing fault for induction motor, this paper chooses Motor Current Signature Analysis (MCSA) to diagnose bearing fault for marine induction motor. Motor Current Signature Analysis establishes function between the character of bearing fault with the eigenfrequency of motor current. As long as picking up the character of bearing fault in motor current, the bearing fault for marine induction motor can be diagnosed.The character of bearing fault for marine induction motor is extracted difficultly, because it is very weak and polluted by noise. Comparing FFT with power spectrum estimation, this paper chooses improved periodogram (Welch) to pick up the character of bearing fault for induction motor. For the better effect, it does some simulation analysis to choose window function, subsection number and sampling number.This paper chooses hall element to measure motor current in the diagnosis system. Digital Signal Processor TMS320LF2407A is used to processing signal. PROFIBUS-DP slave station constitutes distributed fault diagnosis system.This paper makes A/D conversion for the signal and designs the program of improved periodogram (Welch) in the diagnosis system. Also this paper completes the software design of PROFIBUS-DP slave station, compiles GSD of slave station and builds the field bus network of PROFIBUS.