Direct Torque Control Of AC Hoist Technology

At present, the actual production of use mine hoist is quite a number of AC hoist in our country. Because of the importance of mining equipment, the safety and reliable operation of AC Hoist is great responsible for the normal mine production. This paper based on the results of previous studies, from the perspective of AC variable speed, research mainly for Building overall modeling, simulation, analysis which based on direct torque control technology and space vector modulation direct torque control strategy. Meanwhile, this paper also creates AC motor modeling and simulates it.The studies of this paper is beginning of the mathematical model of Asynchronous motor, get the motor space equation of state, and building the simulation model. Then, the paper introduces the traditional principles of direct torque control, and analysis of the direct torque theory which nearly circular flux.Determine the flux amplitude and torque range and its size through the Real-time. From the table, select the appropriate voltage vector, and then use the MATLAB/SIMULINK simulation software create the overall Modeling and simulates it. The results show that control of direct torque make having a simple calculation, smaller dependence on motor parameters and fast torque response characteristics. So asynchronous motor become one of the most important control strategy.Based on the space vector modulation of direct torque control strategy and take the motor and PWM inverter as a whole, make the motor can obtain constant magnetic field which similar to the ideal circular. Solve the torque, current, flux ripple, inconstant switching frequency problems. Focus on the design of the SVPWM module, the expectations of the synthesis of voltage space vector and the judge of the interval vector, calculating the on-time and time of the switching device at last. The simulation results show that the based on the space vector control can effectively improve the performance of direct torque control system. Decrease the conventional direct torque control flux and torque ripple and make the invert work at a constant switching frequency.At last, this paper summarizes those studies, and shows the research key point and directions in the future.