Study On Frequency Characteristic Compensation Of Field Low-speed Dynamic Unbalance Measurement System

Field balancing technology has been widely used in the monitoring and maintenance of rotating machinery.With the energy consumption,cost and efficiency being paid more and more attention,the accuracy of dynamic unbalancing measurement at low-operation-speed becomes a demanding issue.The sensitivity of the vibration pick-up sensor and the passband capability of the measurement circuit in the low frequency area are the key factors to the low-speed unbalancing measurement.Upon the requirement of low-speed field dynamic unbalancing measurement,the sensor's characteristic in frequency domain is studied and in-situ frequency characteristic compensation approach of measurement circuit is analyzed.As the unbalance vibration is very weak at low rotation speed and the response of the vibration pick-up sensor at low-frequency is attenuated,this research based on the zero-pole configuration,the compensation of frequency characteristics of the sensor is studied and the design of the compensation network is studied.The optimal parameters are obtained through simulation,and the compensation circuit is constructed and its feasibility is verified by experiments.To compensate for the attenuation and phase shift caused by the frequency characteristics of and the low-pass filtering circuit in long-term usage,an in-situ parameter identification approach is proposed,and the identification approach is a self-contained one without the need of any additional resource..The error caused by square wave and triangular wave excitation and the optimal series of excitation frequency is analyzed and discussed.The effectiveness of in-situ parameter identification is proved by experiments.At the end of the thesis,the details of the modules human-machine interface are described in detail.The communication between upper and lower computers is established with CAN bus technique.