| The permanent magnet(PM)machines are widely used in many fields,suc h as daily life,industrial and agricultural production and military affairs,because they have many advantages including Simple structure,small volume,light weight,high output torque and reliable operation than traditional electromagnetism machine.The performance of the machine should be higher to meet the development of science and technology and the progress of human society.Therefore,the study of high torque density,high reliability,high fault-tolerant capabilities and low ripple torque in a new machine structure to improve people's living standards,improve electricity consumption efficiency is particularly important.The fractional slot permanent magnet machine with similar slot and pole numbers has the characteristics of high torque density,good performance and economical application.The paper studied and compared the permanent magnet machine with slot and pole number differing by two and analyzed the advantages of machines with different winding configurations and proposed unequal tooth width structure to increase the torque density of the machine to meet the requirement of low speed and high torque density of the machines in the application of digital turntable,wind power,household electrical appliances.Firstly,the matching principle of slot and pole numbers of permanent magnet motor with similar slot and pole number was investigated based on the matching principle of slot and pole numbers of fractional-slot permanent magnet motor.Following the mathematic model,structure and winding con nection mode of motors are studied.Then the generation mechanism and suppression mode of the cogging torque of the permanent magnet motor were analyzed.Secondly,Four types of 230 W PM machines,that is,12 slot /10 pole and 12 slot /14 pole which slot number and pole number differ by two with alternative teeth winding and all teeth winding respectively were chosen as the investigate machines with reference to conventional fractional-slot machine in which the ratio of slot number and pole number is 3:2 namely 15 slot /10 pole machine.The rotor structure,stator winding distribution and material selection were preliminarily designed,and the finite element models(FEM)were established.Then the machine dimension,rotor structure and stator winding distr ibution were rectified repeatedly based on the simulation results.Finally,the design of machine was determined.Finally,the performance advantages of the machines with similar slot and pole number compared with conventional machine with fractional-slot machine were investigated.The performance characteristic of machines which slot number are two bigger than pole number and pole number are two bigger than slot number and machines with similar slot and pole number however with different winding connection styles were studied.The reasons for the increase of the torque density and the design method of the unequal tooth structure were studied for unequal teeth PM machine.The output torque,cogging torque and pulsating torque of the machines were compared in detail when employed different design schemes for stator tooth and stator tooth top width which provides the basis for the design of the unequal tooth motor with similar slot and pole number. |
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