| Permanent magnet motors have the advantages of small size and high efficiency,and have been applied widely in industrial and agricultural production.With the emergence of permanent magnet materials and the development of permanent magnet motor manufacturing technology,if an integer slot distributed winding is used,the difficulty of motor manufacturing will increase.And the insulation of the phase-to-phase materials will increase,making it difficult to meet design requirements.Just as this fractional slot concentrated winding motor has attracted more and more attention,its application fields mainly include electric vehicles and elevators,so it is necessary to study the fractional-slot concentrated winding permanent magnet motors.First,Introduction.The research background and significance of this topic are introduced.The research status and development trend of fractional-slot concentrated permanent magnet synchronous motor at home and abroad are described.The main content and chapter arrangement of the article are determined.Second,the basic theory of permanent magnet synchronous motor.The basic structure of the fractional-slot concentrated winding permanent magnet synchronous motor is introduced.The working principle of the permanent magnet synchronous motor and the mathematical model of the permanent magnet synchronous motor are discussed.Third,fractional-slot concentrated winding permanent magnet synchronous motor design and its harmonic analysis.The electromagnetic design of the fractional-slot concentrated winding is introduced.The constraints and selection conditions of the slot-fitting of the fractional-slot concentrated windings are analyzed.The final selected slot-fitting is 9-slot 8-pole,12-slot 8-pole and 12-slot 10-pole,respectively.The finite element analysis method is introduced.The two-dimensional finite element model is established to obtain the magnetic field waveform of the permanent magnet.According to the Fourier decomposition,the permanent-magnet synchronous harmonic data of the fractional-slot concentrated winding with 3 different slot-poles is obtained.Finally,the motor is subjected to radial force wave analysis.Fourth,the analysis of cogging torque of permanent magnet synchronous motor with fractional slot concentrated winding.The reason of the cogging torque of the fractional-slot concentrated winding permanent-magnet synchronous motor was introduced.The expression of the cogging torque of the fractional-groove concentrated winding permanent magnet synchronous motor was analyzed by the analytical method.Three kinds of analysis were performed by the finite element analysis software Maxwell2 D.The cogging torques of different slot poles are matched to obtain the minimum torque of the 9-slot 8-pole cogging torque.And then the effect of the slot on the cogging torque caused by four factors is analyzed,including the notch width,arc coefficient,eccentricity and auxiliary of the fractional-groove concentrated winding permanent magnet synchronous motor.Fifth,the analysis of unbalanced magnetic pull force of fractional-slot concentrated windings.The reasons of the unbalanced magnetic pull force are introduced,and the analytical expression of the unbalanced magnetic pull force is discussed.The waveform of the radial unbalanced magnetic pull force is obtained by the finite element analysis software Maxwell 2D.It is analyzed that the air gap flux density is an important reason for the unbalanced magnetic pull force.By changing the width of the notch to reduce the air gap flux density,the magnitude of the unbalanced magnetic pull force is reduced. |
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