Research On Speed Control Systems Of AC Induction Motor Based On DSP

Vector control technique presented in early70s is a high-performance speed control strategy forinduction motor (IM) drives. This method was investigated and discussed for many years and havenow become the most common industry standard. Direct torque control (DTC) technique is anotherhigh-performance control method for IM drives which was put forward after vector control technique.DTC system, characterized by its simplicity, better dynamic behavior and robustness, have developeda lot and drew much attention.In this paper, theories of vector control, DTC, space vector pulse widthmodulation (SVPWM) and sliding mode were discussed, the vector control system (field-orientedcontrol) of IM was established and DTC systems based on sliding mode control theory were built, thecontrol systems were verified by digital simulation and experiment. The major work of this paperincluding:1. Discussed the theory of vector control in-depth, built up a speed regulating system based onFOC and SVPWM strategies.2. According to the characteristics of FOC and traditional DTC, a new DTC scheme wasproposed, two regulators with sliding-mode control theory were designed to replace common PImodels for torque and flux regulating respectively, and SVPWM was included into this scheme toreduce torque ripple. Further, with sliding-mode control a speed observer was designed, and a newsensor-less speed DTC system was built.3. The mathematical models of mentioned systems were established and simulated inMatlab/Simulink. The simulation results showed that the proposed DTC system can well improve theperformance of the speed control system, the sliding-mode speed observer also has much betterperformance in estimating rotor speed.4. Digital control system based on TMS320F2812DSP was built and the speed control systemwith FOC scheme was experimented.The satisfied system performace was dementrated by experimentresults.