| Permanent magnet brushless motor(PMBM)not only has the advantages such as good speed control,easy control that all brush DC motor has,while also has longer life and more reliable operation as it eliminates the brush and commutator,so many companies apply it to electric vehicles.However,during the manufacture of the motor,windings occupy a lot of space at the end without generating energy,which limits the promotion and application of this kind of motor.Soft Magnetic Composite(SMC)is a new type of permeability magnetic material by powder metallurgy technique.The major advantages of the material include isotropy magnetic and thermal properties,low iron loss at high frequency and easy molding.SMC PMBM is a novel one with SMC stator material instead of laminated silicon steel,the use of SMC material makes the motor have a three-dimensional magnetic circuit,which not only saves the usage of windings,reduces the axial length of the motor,but also improves the performance.At present,there are few researches on SMC-based PMBM.Therefore,its related research not only has important theoretical significance,but also has important practical value.The main contents of this paper are as follows:Firstly,the background and significance of this research are described and the research status of what is related to SMC PMBM is reviewed,including the PMBM,SMC motor and SMC PMBM related to this subject.Then the main contents of this paper are given.Secondly,the ferromagnetic properties of SMC material and laminated silicon-steel were compared and tested.First,a comparative performance test with regard to SMC and laminated silicon-steel test block is initially carried out.Then in view of the difference between the test block and the actual motor structure,they are applied to the same structure of a 3-phase 10 pole 12-shot PMBM,separately used SMC,50SW300 and 35SW300.Through the experimental tests,it is concluded that the SMC material has lower magnetic characteristics than laminated silicon steel materials under the conventional frequency and flux density.Therefore,when applying SMC material to motors,the isotropic magnetic properties of SMC material should be fully utilized.The SMC material should be used in a motor having a three-dimensional magnetic circuit structure or convert a general two-dimensional structure motor into a three-dimensional magnetic circuit motor.Thirdly,compare the difference between the SMC-2D PMBM and the SMC-3D PMBM,study the effect of slot width on the performance of SMC-motor and Si-motor,propose a 2D equivalent design method for the SMC-3D PMBM.Through comparison with the common 2D structure SMC motor and silicon steel one,the advantages in terms of torque density and electromotive force of SMC-3D motor are clarified.Due to the 3D structure of the SMC-3D motor,its related research can only be carried out in a 3D finite element field,which takes a great deal of time.Therefore,a 2D equivalent method is proposed to facilitate the design of the SMC-3D motor.Then,in view of the different magnetic properties of SMC material and silicon steel material,the influence of slot width on the performance of the two kinds of motors is studied.Finally,a prototype was made and the feasibility of SMC-3D motor was proved through prototype experiments.Fourthly,a novel structure of SMC-Si hybrid PMBM and the related study are proposed.Due to the difficulty of machining and large loss in SMC-3D motor,a novel stator structure of SMC-Si and the corresponding PMBM are proposed.The stator core can be designed with a 3D magnetic circuit structure due to the isotropic magnetic characteristics of SMC,and therefore enhancing the motor power density.In addition,the use of silicon-steel decreases the amount of permanent magnet caused by SMC's low permeability,and high iron loss caused by SMC's high iron loss at motor operating frequency range.Through the comparison with the Si motor and SMC-3D motor,it is founded that the performance of the hybrid stator motor is the best.Lastly,conclude the whole article. |
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