18-gon Flux Direct Torque Control Algorithm Design And Implementation,

The direct torque control theory is a kind of new control theory followed the vector control theory in the field of alternating current drive. The method has the performance of quick reaction, simple structure, and easy design because it hasn't complicated vector transform. Classical direct torque control method adopts the technique of 6 polygon flux linkage voltage modulation. It will generate torque pulsation and harmonic interference. In the process of the alternating current drive technique development, It is one hot research direct about eliminating harmonic.The paper analyzes the method of 6 pulse switch mode DTC in existence and point out its excellencies and disadvantages, then a new method of 18 pulse switch mode DTC is presented, the implement method is given base on this 18 polygon flux linkage voltage modulation, the paper also gives the theory analysis, harmonic disposal ,and implemental mode. The method is proved to be effective through virtual object experiment and real inverter test .Through the experiment, it is shown that the method of 18 pulse switch mode DTC can solve the high harmonic proportion problem produced by 6 pulse switch mode efficiently. Harmonic reflected from inverter to DC circuit is weaken evidently. The method decreases the low frequency torque pulsation and improves control performance a lot.In this paper the DTC systems that have different stator flux curves are simulated detailedly by Matlab/Simulink. The systems are also simulated by half practicality method ,the simulation result accords with the analysis of theory.