| The injury of the environment from the traditional internal combustion enginevehicle is larger and larger. This situation forced people to think about the future ofthe car driving force, and speed up the transportation energy strategy transformation.So hybrid cars which are between traditional and pure electric vehicle become the hotspot researched by people.Compared with traditional automobile, the special place of hybrid electricvehicle is the increased battery-motor system. This paper is researching the motordrive system base on the point. Through the comparison and analysis, this paperselects induction motor, and the direct torque control technology as the controlstrategy. Direct torque control technology is to analyze the mathematics model of theinduction motor in the stator coordinate system. This paper analyses the direct torquecontrol theory and builds the simulation model in the Matlab/Simulink situation basedon the model of induction motor, and carries out the simulation experiment. Byobserving and analyzing the result of the experiment, we can come to the conclusionthat the prominent advantage of the direct torque control technology is the fastresponse. But this control technology has some disadvantages, for example the statorflux linkage locus pulsation, torque ripple and current waveform disturbance fromharmonic. And this situation is more serious in low speed.In high performance induction motor control system, speed control isindispensable, but the installation of speed sensor, for example, photoelectric encoder,will bring a lot of installation and maintenance and other aspects of the problem forcontrol system. So people put forward speed sensorless control system. Here by usingthe extended Kalman filter to achieve speed sensorless technology. On the one handwe observe the stator flux linkage by using of extended kalman filter, on the otherhand, using it to realize the speed of recognition, Improved the control effect. At the same time, the extended kalman filtering observer also considered the noise, so it hasthe great practical significance. By mastering the extended kalman filtering principleand deduction, this paper designs the direct torque control system based on extendedkalman filtering, and sets up the simulation model in the Simulink. The simulationresults show that the improvement measures is useful, it can improve thedisadvantages of the above traditional direct torque control technology obviously andimprove the direct torque control performance effectively.The mathematical model of induction motor ignores many factors. However theenvironment is more complex in the actual operation and the motor drive system isinfluenced by environmental factors inevitably. These will affect the controlperformance of the control strategy, even will lead to failure. So it is necessary toverify the effectiveness of control algorithm. In view of the completeness of inductionmotor model in AMESim, this paper not only includes the front modeling factors, butalso consideres the temperature and some external interference. So this paper uses themotor model in AMESim to instead of induction motor model of control system. Atthe same time, the inverter and the driving part are also builded on the software; thiscan verify the effectiveness of the control algorithm and assess the control effect. Wecan verificate the test results by combined simulation in the AMESim andMatlab/simulink. The simulation results show that the control strategy in this paper isuseful in the permitted error, and it is meaning in the practical application. |
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