Performance Analysis Of Novel Fractional-slot Interior Permanent Magnet Machines

The fractional slot interior permanent magnet machines have the characteristics of simple manufacturing,low power loss,high filling factor and high torque density compared with integer slot permanent magnet machines.It is widely used in modern human daily life.With the improvement of the life quality,the performance of permanent magnet machines put forward higher requirements.Therefore,it is of great significance to study the new high power density permanent magnet machine for energy saving and emission reduction.In order to get the maximum torque density and reduced the ripple torque,two machines with different slot-pole combination are selected.In order to reduce the magnitude of magnets,two different rotor structure models with single and double "V" type are selecte dFirstly,On the basis of the slot pole combination of fractional slot machines,the advantages and disadvantages of high power density fractional slot machines with Z=2p ±1 combination are analyzed.In order to solve the asymmetrical spatial distribution of the odd number slot machine winding,the slot pole combination of Z=2(2p±1) is adopted.The structure of the built-in "V" type rotor structure is analyzed in detail.The cause of cogging torque is analyzed based on the energy method.Secondly,according to the principle of the high power density fractional slot machine,9 slot 10 pole motor and 18 slot 10 pole motor are selected.In order to improve the winding factor of the 18 slot 10 pole machine with one coil,two coil pitches winding is adopted,which can solve asymmetry of the motor windings,and also improved the winding factors.The dimension of the stator and rotor of is determined.The rotor structure are single layer and double layers ‘V' shape type.The winding factors of the three kinds of machines are derived in details.The finite element software is used to optimize the design,and the dimensions of the motors are finally determined.Finally,the finite element method is used to compare the no-load characteristics,torque characteristics,flux weakening operation performance,motor loss and efficiency.The results show that the 18 slot 10 pole motors have the better performance.