Study On The Key Control Techniques Of High Performance AC Drive System

The AC motors are nonlinear complex system with electric fields,magnetic fields and force fields complected strongly, Three main characteristics of the AC motors are nonliear, coupling and slow time-varying, For the sake of further exaltation performance, key issues are how to overcome or represse the problems brought by the three characteristics of the motors. Supported by the 973 National High Technology Research and Development Program "high speed numeric machine dynamic mode and their high precision control", this dissertation concentrates its attention on the key Techniques of high performance AC drive system. The main research contents include a few aspects:1. Build up ideal models for synchronous and asynchronous AC motors in static reference frame and rotary reference frame respectively. Based on the ideal models, vector control and direct torque control method were applied on AC driver system, decouple between the rotor torque and the rotor flux linkage are realized in great degrees. And then, an extension of the DTC scheme is also provided based on the conventional way. The main features of the conventional DTC are fully preserved, namely, its simplicity and its excellent dynamics performance. Moreover, the amplitudes of the motor quiver have also been bated by means of the space-vector modulation (SVPWM) function. Simulation and experimental results are given which confirm the validity of this approach.2. Parameters of the AC motors have slow time-varying characteristics, on-line parameters estimation based on forgetting factor least square method can track the variation, Another method of on-line parameters estimation based on extended Kalman filter(EKF) method is also presented, only rotor resistor is real-time estimated, and variation of other parameters of the motor are considered as system noise, experimental results demonstrated that the two methods have not only satisfied the demand of the motion precision, but also the Real-time demand.3. To the nonlinear motor system, one method is finding a controller which is not depended on or slightly depended on the controlled system. Fuzzy control is just belonging to this class. To find the optimal parameters for the fuzzy control, and the accelerated simplex search algorithm can help fuzzy controller to find the optimal fuzzy parameters. The most advantage of the sliding control is its robness of the disturbance, so the adaptive control from fuzzy and sliding control combination can enhance the accuracy and sensitive response for the AC motor.4. Another method solving nonlinear problem of the AC motor is transforming the nonlinear system to equivalent fictitious linear multi-input and multi-output system (MIMO) via differential geometry tools. And then controller can be designed by classic linear control theory. Meantime, decouple between the rotor torque and the rotor flux linkage is realized in the dynamical state. Simulation results show that this kind of servo controller has good dynamic performance and actual application value.5. The control circuit is based on the TMS320F2812 which can realize the motor control algorithm in C language. IPM is the core part of the main circuit which includes inverter and the motor driving circuits and other detected circuit. Current,voltage and temperature sample circuit are also designed to buildup the integrity hardware platform for AC servo system.6. In application part, the above mentioned theory such as DTC,EKF,FFLS,Fuzzy Slide Adaptive Control(FSAC) were successfully applied in the speed control of the motorized spindle and position control of the linear AC motors. And experimental results approve their validity and efficiency.During the research period, parts of research obtains are already used for produce, achieve a good economic benefit.