Research Of Rotor Optimization Design Of Novel Magnetic-Barrier Modulated Doubly-Fed Brushless Machine

The Doubly-Fed Brushless Machine (DFBM) is a new type of AC machine that is attractive for converter-fed variable speed drive systems and variable-speed constant-frequency (VSCF) wind power generation systems. The system of the BDFM has a simple structure without brush and slip-rings on rotor which achieves the goal of brushless, thus it is of high reliability in engineering application. It also has superiorities such as various operation modes and easy to adjust active and reactive power.In magnetic resistance type rotor of DFBM, the novel magnetic-barrier modulated rotor not only has better magnetic coupling performance, but also has no windings in the rotor, so such rotor has unique advantages for improving the operating efficiency. Take a 1.5kW novel magnetic-barrier modulated DFBM as an example, the work of this thesis focuses mainly on the optimized design for its rotor, the following parts are included.Firstly, based on the winding function theory, the fundamental and harmonic winding functions of stator windings of novel magnetic-barrier modulated DFBM are derived with discrete thought, so are the fundamental and harmonic components of air-gap flux density. Then, unit area radial force of stator's inner edge is calculated based on air-gap flux density. The comparison of air-gap magnetic field distribution, radial force wave of rotor's outer edge and radial force of whole rotor among motors with three kinds of rotor pole-pair are given in this thesis.Secondly, according to the electromagnetic field theory, the Maxwell-2D models of 1.5kW novel magnetic-barrier modulated DFBM with three kinds of rotor pole-pair number are established, and electromagnetic force under static and synchronous state was calculated using Ansoft software. Then, the comparison and analysis of the whole rotor's electromagnetic force among the three kinds of motor are made respectively under the two operation states.Finally, this thesis embarks from basic theory of Electrical Machines, combined with the characteristic of novel magnetic-barrier modulated DFBM, and focuses on the influence of motor performance when the width of magnetic layer, the width of magnetic-barrier layer or the number of magnetic layer changes. With Ansoft finite element software, this thesis establishes four motor models with different rotor structure parameters. Then, this thesis calculates the electromagnetic field of these four kinds of models, comparatively analyzes the magnetic field distribution, the torque capability, the end winding characteristics, the core losses and the rotor's electromagnetic force.