Study On Load Torque Oberver And Its Application In Power-Fed AC Motor Experiment System

The performance of motor system depends on the output torque, online real-time accurate detection to the instantaneous motor torque is the key to achieving high-precision control and predominating behavior, so the load torque measurement is very important. On the other hand, Torque measurement is indispensable for the test of some mechanical equipments, it is also a familiar control parameter in the modernization production process. With the rapid development of the modern computer technology, it led to the intelligence of scientific instrument. So the research on the high cost performance and stable performance of torque testing system is imperative.Based on Multi-rate Sampling Control theory, Extended Kalman Filter (EKF) theory and the analysis of Vector Control System of induction motor, calculation and online estimation of load torque is derived with the mathematic model of induction motor. Firstly, the stator flux of induction motor is calculated based on multi-rate theory, and the load torque is calculated through the stator flux. Secondly, the load torque is online estimated, which is considered as a state variable of induction motor. With the combination of Multi-rate Sampling Control theory and Extended Kalman Filter theory, the Multi-rate Extended Kalman Filter theory is derived.Using the small level power supply, Power-fed high power AC Motor Experiment System is studied, which has high efficiency through feedback DC energy to power system. This is the outstanding merit of the experiment system. The experiment system includes two induction motors on a common shaft. One is used as the drive motor, and the other is the analog load. An algorithm of load estimation based on EKF is applied to the Power-fed AC Motor experiment system. Two-motor-cooperation-control of Power-fed AC Motor Experiment System is implemented through estimation of the rotor speed, the flux and the load torque simultaneously. So, vector control of two AC asynchronous motor is addressed by making full use of the advantages of Power-fed AC Motor Experiment System.Based on theory analysis, the model of the experiment system is established and simulated by employing MATLAB/SIMULINK. The results show the effectiveness of the proposed methods.