Research On

As a kind of indispensable power equipment in modern industry, asynchronous motorwith high-performance speed control and intelligent control which has become the researchfocus of researches in this area. Direct torque control is another new type of highperformance AC variable frequency technology after vector control. It has been widespreadconcern in the industry because of its direct control means, fast system response, goodrobustness, and excellent dynamic and static characteristics.Firstly, in this thesis, the development of AC speed regulating technology wasreviewed. Then, it analyzed asynchronous motor’s dynamic mathematics model andelaborated the basic principle of direct torque control system. In order to reduce the fluxand torque ripple of ac motor operating on low speed, the paper introduced the SVPWMtechnology. In order to improve the stability of rotor speed, the paper optimized thetraditional PI controller by using the algorithm of fuzzy neural network. In order to savesystem costs and save installation space, the paper estimated rotor speed using MARSalgorithm, which could real-time track the actual rotor speed. The results of simulationunder Matlab/Simulink software environment validated that the improvement system inthis paper has low ripples, small overshoot, and high stability advantages.Based on the simulation, this paper completed the design of software and hardware ofasynchronous motor direct torque control system, In Which, Hardware part mainlyincluded main circuit with a core of TMS320F2812MCU, detection circuit and keyboarddisplay circuit, and software part were C codes depended on CCS3.3platform, mainlyincluding main program and interrupt service program, and the DTC algorithm wasrealized in the interrupt service program. Finally, asynchronous motor variable frequencyspeed regulation experiment was done in this paper. The experiment results show that thecontrol scheme can be satisfied the requirements of high-performance motor speedregulation system.