Study On Parameter Identification Methods And Digital Control Technology For AC Induction Motor

The methods of parameter identification and state estimation are studied in this thesis for AC induction motor, which is a multi-variable, strongly coupled and parameter-variable nonlinear control system. The complete digital control scheme was also presented with the design of hardware and software for AC induction motor.High performance control methods and recent development of parameter identification and state estimation of AC induction motor are expatiated in this thesis. The virtue of digital controller and simulated controller was presented based on comparing with them and analyzing effect on motor control performance in theory because of parameter variety of AC induction motor.The direct vector control methods were studied based on Luenberger flux observer after introducing math models of the AC induction motor in 2-phase and 3-phase coordinate. The identification method of rotor resistance based on MRAC was presented considering the effect on FOC because of variety of rotor resistance and this system composed of above the observer with rotor resistance identification meets with Popov's theory. Speed estimation methods of AC induction motor were studied and their excellence and shortcoming are compared with. In order to reduce control method to depend on motor model, parameter identification of AC induction motor based on neural network is presented.The realization scheme of digital control system based on the digital signal processor was presented. The design of both software and hardware was optimized, and so the system can operate in real time with safety. Aiming at the limited word length of fixed point DSP TMS320F240, approaches for increasing the calculation precision and speed of the control algorithm were studied. And the control soft is programmed with assembly language and C program, and the overall digital control was achieved.Simulation results of rotor resistance identification and speed estimate were presented. And experiment results of speed opened-loop constant V/f and speedclosed-loop vector control were also presented based on TMS320F240 DSP in this thesis.