System Research For Asynchronous Motor Speeding Adjustment Feeding By Varible Frequency Converter Base On The Direct Torque Control

Along with the appearance of new electronic elements and intelligent power module, the development of modern control theory and the application of computer technologies, the technology which AC induction electromotor driving renovate quickly, and new control method appears ceaselessly. All of these make the AC induction electromotor driving system to replace DC electromotor driving system in wide range. The AC variable frequency speed regulation is generally acknowledged with excellent speed regulation, high efficiency saving energy, extensive scope of application and other merits in the AC induction electromotor driving technique.Direct torque control technique(DTC) debuted in the AC driving field in 1980,s .It is a new efficient AC drive control technique, which follows field-oriented control technique and intends to exceed field-oriented control technique. The flux and torque of stator of AC induction electromotor are calculated and controlled in the stator-oriented coordinates, are adopted stator magnetic field orientation, are directly tracked. The signal of PWM is built by dint of the discrete adjustment in order to control optimally the state of the switches of inverter and get the high dynamic performance torque response.The main circuit of the system adopts the AC-DC-AC topological structure. The power device uses IPM . In this control system, the main high performance microprocessor chip is 80C196MC which is produced by Intel Company and is special for motor control. Three phase modulating wave is generated by wave form generator which in the chip . This paper details the algorithm structure of DTC based on 80C196MC single-chip computer, the relative parameters'calculation and the setting method of some registers of the wave form generator. The software is finished by assembly language.According to the theory of DTC in the thesis, the simulation model of DTC for asynchronous motor based on MATLAB/SIMULINK is model and simulate. The result of the simulation is fine. The design scheme is debugged on a teaching experimental platform of electric power electron and electric drive in , and the results show that the method of DTC has lower current harmonic, more efficient use of supply voltage, lower noise.