Research On Application Of Intelligence Control Strategies In DTC System

Direct Torque Control(DTC) of asynchronous motors, which has been developed in the recent decades,is a power control method for motor drives. The quick development of DTC makes itself a new high-powered Alternating Current(AC) driving technique. The DTC is good at its robust characteristics, simple realization and excellent dynamic response. In brief,using an analytical method on space vector,DTC technology directly calculates and controls the torque of asynchronous motor under the stator coordinate. On the other hand,in order to get best capability on activity, adopting the stator-magnetic-field-oriented way,DTC technology directly applies optimum control on the switch conditions of inverter and generates PWM signal taking advantage of discrete Band-Band adjustment. The speed sensorless method has been a focus in the field of alternation current drive since it came into being. Using speed sensor not only increases the cost,but has the disadvantage of inconvenient fixing and maintenance. So using software instead of speed sensor,the speed sensorless method, has good application prospect.The paper makes a study of asynchronous motor model and the basic principle of Direct Torque Control. The DTC system that has six-corner and the circle stator flux curve is analysed in details. Then a parameter identification method based on particle aptitude algorithm for DTC system is brought forward and is proved its validity through simulation and experimentation. The new parameter identifier is constructed based on BP neural network optimized by modified particle swarm optimization algorithm (PSO), which improved parameter observing method in DTC. The optimized neural network can identify parameters more effectually and quickly comparing to the old ones in the environment of Matlab/Simulink.The experiment use TMS320F240 DSP chip which is specialized in motor control system. The newest Intelligent Power Module (IPM) is been used as power instrument, its inner protect circuit raise reliability of the system. Theexperiments, results show that the scheme is feasible and effective.