Induction Motor Direct Torque Speed Control System Design And Simulation Studies

Following the Vector Control (VC) technique, Direct Torque Control (DTC) asynchronous motor, which has been developed rapidly in the recent decades is a new AC driving control technique. The DTC system has been widely used in recent years with its simple structure and static-dynamic capability since the theory of DTC was put forward in the 1980s.First, the mathematical model of asynchronous motor is researched thoroughly in this paper. On the basis of the study of the traditional DTC, a new stator flux and torque controller is proposed, and the traditional voltage vector table is replaced by a new table. Because in the traditional switch table uses the reverse voltage vector to cause the torque pulsation the peak-to-peak value to be bigger, the new voltage vector table uses the null vector to replace the reverse voltage vector. But when AC motor run in lower speed , the null vector can cause stator flux weaken seriously, Therefore when the stator flux needs to increase and the torque need not variable, the switch table selects the vector which only causes the flux linkage radial direction increasing. When the stator flux weakens under the limiting value, the radial direction function vector causes the flux rapid increase, achieved both made up the null vector insufficiency, and maintain the null vector merit. The null vector use is unable to realize the torque rapidly to reduce, Therefore uses the multilayer link to the torque control. When the torque leaves the inner rim, the reverse voltage vector starts the function. So it has been able to reduce the torque pulsation, when did not cause the low speed the flux had the weaken, simultaneously also did not affect the system dynamic performance. Then, this paper models and simulates the DTC system in the Matlab/Simulink environment and the result is according to the anticipation.Following, the DTC experiment hardware system based on DSP is constructed, which is composed with two main parts, the controlling circuit (TMS320F2812) and the inverter circuit (IGBT). Other peripheral circuits are demonstrated in detail, such as the speed detection, the voltage and current Sampling, and so onLast the part of software is coded with assemble language in the CCS environment;...