Problemy regulacji momentu i strumienia metodą DTC występujące podczas pracy silnika przy niskich prędkościach kątowych

Direct torque control method proposed by Takahasi and Noguchi in 1985 in spite of its disadvantages (flux vector hexagonal in shape and distorted current for small motor speed) is competitive to the flux oriented methods of control (FOC). Methods of the current controlled AC motor investigations and their results presented earlier by author was applied to DTC method control analyze. Although in DTC method the current components are not controlled directly, the torque and flux control phenomenon is easy explained by the current components i(sq) , i(sd) changes. DTC method operation analysis to explain the flux and current distortion for the small speed of motor operation is discussed in the article. As results this observations the method DTC scheme modification is proposed. The modified DTC method is free from the conventional DTC method disadvantages. The dynamical properties of new method are similar to conventional DTC method. It is important that in the modified method the conventional switching table is used. Correctness of new method is confirmed by laboratory investigations.