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Improve the Direct Torque Control Method for Brushless Doubly Fed Induction Machines

Ghaffarpour, Ali | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47726 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Oraee Mirzamani, Hashem; Barati, Farhad
  7. Abstract:
  8. The Brushless Doubly Fed Induction Machine (BDFIM) has the potential to be used as a generator or motor in adjustable speed variables. But the most important application for the BDFM is to work as a wind generator. Due to this ability it can be considered as a rival for the Doubly Fed Induction Generator (DFIG) that is the most common type of the wind power generators nowadays. Because of problems of relater to brushes in DFIG, the BDFM has more resisted structure compared to the DFIG. Thanks to the special “nested loop” structure of rotor and two different coils on the stator without direct coupling between them, three different operation modes are possible for the BDFM.The synchronous operation is the main and most interesting function mode that distinguishes BDFM from other machines. Good dynamic and steady-state behaviors are necessary to use the potentials of the BDFM. In the past, there have been valuable efforts to reach this aim but there are still many problems and this thesis was done in order to fulfill this goal. In this thesis the fluxes in the BDFM air gap by the magnetic viewpoint were studied and suitable torque formula was extracted to be used for the Direct Torque Control (DTC) strategy. Using the vector model of the machines, the function of closed-loop system was proven in the synchronous operation. In order to solve the problems caused by the variable switching frequency in the classical DTC strategy, a method has been proposed to solve the problems of the implementing the DTC on the BDFM. The machines model was simulated in the MATLAB and simulation results illustrate the verification of proposed methods on the BDFM
  9. Keywords:
  10. Brushless Doubly Fed Induction Machine ; Direct Torque Control ; Electrical Machines Control ; Fixed Switching Frequency ; Electrical Machine Synchronues Working ; Wind Energy Generator

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