Base On Direct Torque Control Of Asynchronous Motor Wide Speed Range Research

Asynchronous motor is an integral part of the industry, agriculture, daily life, motor iswidely used in national life in all sectors as the driving equipment, speed control of inductionmotor has been the concern of scholars, with the increasing control requirements, wide rangeof speed regulation is accepted by all applications, the current control of above the base speedis mostly implemented in vector control, the study of direct torque control is mostlyimplemented with the hexagon flux, can not guarantee the stator flux as a circle, so theresearch on wide speed range of direct torque control has important significance.In this paper, using asynchronous motor as the research object, in order to achieve a widerange of motor speed, based on the analysis of speed control method of asynchronous motorand control method, the direct torque control structure were studied, aim at shorting largetorque ripple of direct torque control, analysis the space vector pulse width modulationtechnical characteristics, and established direct torque control of space vector pulse widthmodulation system model based on the simulink environment, analysis the operatingcharacteristics of asynchronous motor, presents the PI speed controller with adaptive torqueconstraint, the maximum torque in the constant torque region is constrain given value, inconstant power region, the torque is lower with the increase of speed, constant output power asthe constraint condition, the simulation results show that the proposed method can achieve awide range of motor speed, and reduce the time to adjust speed. Direct torque control of spacevector pulse width modulation needs two PI controllers respectively to control the torque andflux, PI controller parameters tuning is a difficult problem, fuzzy PI controller of DTC isdesigned, the input of torque controller is torque error and error change rate, integral andproportional change coefficient of the PI controller are outputs, designing adaptive fuzzy PIflux and torque controller, the simulation results show that the designed controller can betteradapt to the motor parameter variations and realize a wide range of speed regulating.