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Harmonic Analysis of Brushless Doubly-Fed Machines

Soleimani, Amir Hossein | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50422 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Oraee, Hashem
  7. Abstract:
  8. The Brushless Doubly-Fed Machine (BDFM) is a machine which incorporates the robustness of the squirrel cage induction machine and the speed and power factor control of a synchronous machine. All of these advantages are obtainable from a relatively low rating power electronic converter (e.g. 30 % of the machine’s rating). The stator of a BDFM is furnished with two balanced three phase windings of conventional design (power and control winding). These windings differ in pole number and are often excited at different frequencies. Hence, there is no direct magnetic coupling between them. The power winding is connected to a constant-voltage, constant-frequency source and the control winding is excited via a fractional rated bi-directional power electronic converter. BDFM has three modes of operation depending on its winding excitation, include: simple induction mode, cascade mode and
    synchronous mode. The rotor of the BDFM carries a cage of special design. The essential requirement for BDFM action is that the frequency and distribution of the currents induced in the rotor by the air gap field of the first stator winding matches that induced by the second.This thesis discusses the modeling aspects and analysis of brushless doubly-fed induction machines.In modeling part, a model of the machine is obtained which is able to represent its behavior in time of being imbalance in excitation, having disturbing harmonics in supply and able to consider Saliency and Slotting effects. The proposed model is based on the concepts of the generalized harmonic theory of electrical machines and the modified dynamic equations of the coupled-circuit approach. To validate the proposed model, equations of finite element magnetic model which make it possible to simulate the performance of the machine, are extracted and required simulations are provided. Simulation results notifies that there is a meaningful correlation between the established results from two simulation methods and that verifies the proposed model. In this model, the specific formation of conductors is considered
  9. Keywords:
  10. Brushless Doubly Fed Induction Machine ; Nested Loop Rotor ; Finite Element Model ; Harmonic Block Model

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