Electromagnetic Field Analyse Of Modular Stator Structure Low Speed Permanent Magnet Bureshless Direct Cuurent Motor

Modular stator structure low speed permanent magentic brushless direct current motor is a new topology of electrical machine. Multipoles, low speed and high torque is its distinct characters. It adopts modular stator structure so that it can be made into relatively more pole number. There are several small armature projections whose dimension is 1/3 of pole pitch in the stator, which cause others stator teeth pitch is full pole pitch and induced electromotive force waveform of each phase is approach trapeze wave. The tooth width of the motor is one full pole pitch and armature windings is full pole pitch concentrated windings so that winding coefficient is 1 and utility efficient of windings is higher. The concentrated winding of each phase is separately wound on consective teeth so that the phase windings don't have overlap. This is not only a convenience of manufacture, but also the end of winding is shorter. The aount of copper and copper loss are reduced, so efficiency is high.Finite elment method is a numerical method, which is used to analyse structure or field. Its main idea that structure or field, which is made of consective dielectric, is discreted into elements that connected by limited nodal points to analyse. The method, which based on the theory of variation and the measure of discretizational resolver, invert conditional variation into object to resolve inner electromagnetic of the machine. The inner electromagnetic of modular stator structure low speed permanent brushless motor is resolved in this paper.The structure of the machine is mainly discussed in this paper. The relation between topology structural parameter and poles number of the machine is brought forward and cogging torque and corresponding induced electromotive force are concluded. After the calculation and analysis of different dimensional air-gap magnetic field of this machine, design data of the machine is presented and structure design and magnetic circuit calculation of the machine is completed. The resolve result indicate that phase induced electromotive force waveform of three phase stator winding is trapezoidal wave, and the flat-topping is approach to 2Ï€/3 electrical angel. The result also approved that there are only three and triple cogging torque in the machine; the others cogging torque is eliminated. Beause of the merits above-mentioned, this kind of stator strcture permanent magnetic electrical machine is especially suited to be low speed and high torque direct cuurent brushless motor or direct drive wind generator.