Flux Reverse Permanent Magnet Motor

Flux reversal machine (FRM) is a special doubly salient permanent magnet machine. By this time, it is not been systematically studied, whether on the structure or the performance. The shortages restrict further development of FRM. Cogging torque ripple is one of the problems that have not been solved. There have been some methods of weakening the cogging torque, and can weaken cogging torque well, but the shortcomings made them unpractical to produce. So this thesis studies the methods of weakening cogging torque of FRM and the impacts on electromagnetic torque. Based on the existing research results and considering the characteristics of FRM, a new effective method is proposed to weaken cogging torque of FRM. It uses rotor teeth alternative and subsective structure. This method makes use of the rule of variety of cogging torque with rotor teeth change, and the cogging torque of two parts of FRM have opposite phase, so the total cogging torque is weakened.The basic structure and working principle of FRM is discussed in this paper. It's mathematic model is deduced. The methods of optimum designing magnetic structure in FRM, which based on fully considering of the magnetic field characters, are proposed in this paper. The methods weaken cogging torque in FRM effectively and make it operate steadily on the premise of guarantee its own merits.Finite element method is used to analyze the electromagnetic field. The trend of cogging torque is compared with electromagnetic torque. The principle of weakening cogging torque is that the electromagnetic torque should been smooth and not been reduced much. First, this thesis makes analysis of impacts on cogging torque by rotor teeth change and the harmonic components of cogging torque. It is found the rule of the periodical variety of cogging torque by length of rotor teeth arc change. A method of weakening cogging torque by rotor teeth alternation and subsection is proposed. The results of electromagnetic field calculation prove that the method is effective. At last the impacts of this method on electromagnetic torque is considered and analyzed. The result indicates that this method is feasible.