Design And Study On Electromagnetic Fields Of MW Class Doubly-Excited Brushless Wind Power Generator

In recent years, with wind power generation as a clean renewable energy has been extensive concerned all over the world, people pay more and more attention on special MW class generator, which is suitable for wind power generation systems. The MW class doubly-excited brushless generator (DEBG) not only has simple and reliable rotor structure (no brushes and slip rings), but also has good starting performance resemble wound rotor induction machine and good running performance resemble synchronous machine. The DEBG can also realize variable speed constant frequency (VSCF) generation by controlling the frequency or amplitude and phase of excitation windings, and achieve flexible regulation of active and reactive power. Furthermore, the DEBG needs a much smaller power electronic converter in the doubly-excited mode, and the cost of the system is reduced.In this thesis, firstly, the special structure of a MW class Radially Laminated Magnetic-Barrier Rotor Doubly-Excited Brushless Generator (RLMB-rotor DEBG) is introduced, and the principle of VSCF generation is analyzed. According to the characteristics of DEBG, the optimal design project of a1.5MW (2+3) poles RLMB-rotor DEBG is given based on conventional design principle of AC machine.Secondly, according to the application needs, the Maxwell-2D models of1.5MW novel RLMB-rotor DEBG with inner rotor and outer rotor are established respectively by the finite element analysis (FEA) software Ansoft. The electromagnetic field distribution, flux linkage, air gap magnetic density, voltage of no-load operation and the torque capability, efficiency of load operation are calculated and analyzed by Ansoft software. Furthermore, the influence of rotor pole-number to the various performances is discussed. All these results provide theoretical foundation for the optimization of the rotor in practical applications. Ansoft software is used to prove the rationality of the design of DEBG.Finally, due to the high requirements of high power generators for vibration and noise, the radial electromagnetic forces of RLMB-rotor DEBG with inner rotor and outer rotor under no-load and load operation are calculated using Ansoft software. Then the harmonic analysis of electromagnetic forces is studied. All the researches are proposed as a basis for further investigation of the DEBG.