Research Of Motor Vibration Monitoring

With the improvement of industrialization level,electric motors have become the most important driving type of electric equipment in people's life,and are widely used in various fields of national economic production.During the long-term operation of the motor,some faults will inevitably occur.If the motor failures can not be timely and effectively processed,it may cause major accidents.Studies have shown that the motor vibration signal contains a large amount of information relate to the motor's running state.By monitoring the vibration of the motor the operation status of the motor can be effectively judged,and the fault diagnosis and fault warning can be realized,thus the probability of major motor accidents will be reduced.According to the principle of parallel plate capacitance,a capacitive sensor is used to monitor the radial vibration of the electrode shaft.The edge effect of the capacitive sensor is eliminated by adding an equipotential ring,and the incomplete driving cable technique is employed to reduce the influence of parasitic capacitance on the sensor.In addition,Generate a 27 kHz excitation signal using a limiting RC oscillator,and the vibration signal is converted into an AC voltage signal by a three-stage operational amplification capacitance detecting circuit.Then designed a full-wave rectifier circuit to convert the AC voltage signal into a DC signal,and then the eighth-order elliptic anti-aliasing filter circuit is used to filter out the interference signal in the DC signal.Finally,the useful vibration signal is extracted through the zero adjustment circuit.Zoom in separately.In the light of the frequency requirement of the measured vibration signal and the final output voltage range of the detecting circuit,the vibration data acquisition circuit based on STM32F407 microprocessor is designed.24-bit high-precision A/D conversion chip AD7734 and 16-bit D/A conversion chip DAC8541 are adopted.The variable coefficient inertial filtering algorithm is designed to eliminate the random interference signal and the narrow pulse interference signal in the vibration signal,and improve the signal-to-noise ratio of the vibration signal.The vibration data is calculated and displayed by the microprocessor,and the vibration data is transmitted to the Host computer through RS-485 communication.In order to improve the detection accuracy of the vibration signal,the relationship between the vibration amount and the output voltage is determined by curve fitting.The motor vibration monitoring software is programmed by Labview,which can display the vibration signal waveform and its peak-to-peak variation trend.According to the peak-to-peak value,real-time monitoring or offline judgment of the motor running state can be realized,and according to the actual needs of the motor.Artificially set its state judgment threshold.Finally,through simulation experiments,it is verified that the system can reliably judge the running state of the motor under different vibration thresholds of the same vibration signal and different vibration signals of the same judgment threshold.