Investigation On Novel Topologies And Optimization Methods For Permanent Magnet Machines With Soft Magnetic Composite Material Cores

Based on the soft magnetic compsite(SMC)materials,SMC motors that designed by the other researchers and the comparison of SMC motors with different flux pathes and structures,this thesis concludes the general design method and the design guidelines for the SMC motors.By comparing the torque ability to the main magnetic core dimensions of axial flux motor,transverse flux motor and radial flux motor,this thesis finds that the transverse flux motor is suitable for the application that needs the large ratio of axial length to outer radius,and axial flux motor has the same relationship(small ratio of axial length to outer radius)with the radial flux motor when neglecting their end winding length.This thesis proposes several methods to minimize the cogging torque of transverse flux motor and claw pole motor.Moreover,it proposes six novel motor topologies by using the ferrite magnets and SMC cores for the low cost applications.In addition,this thesis uses the multilevel optimization method and multidisciplinary optimization method to optimize the SMC motors.Lastly,it investigates the method of manufacturing the SMC cores by using the powder metallurgy technique.The main work done by this thesis can be summarized as follows:1.This thesis states the design method and guidelines for the SMC motors.It explains the properties of the SMC material and manufacturing process of the SMC machine.It reviews the SMC motor that designed by other researchers in the past decades.Then,it compares five typical SMC motors in the qualitative way.By using the sizing equation method,it deduces the torque ability to the main magnetic core size for the transverse flux motor,radial flux motor,and axial flux motor.It concludes that the transverse flux motor is suitable for the application that needs the long axial length to the outer radius and the axial flux motor has the same torque to the main magnetic core size with the radial flux motor if neglecting the end winding length,and the last two motors are suitable for the application that needs the short axial length to the outer radius.By using the finite element method(FEM),this thesis compares the performance between the outer rotor transverse flux motor and outer rotor claw pole machine.It finds that the claw pole motor has the better utilization ability of the SMC materials and has better performance than those of the transverse flux machine and the axial flux motor has the same relationship of the electromagnetic torque to the main dimensions with the radial flux motor when neglecting the ending winding length.2.This thesis investigates the cogging torque minimization techniques for the transverse flux motor and claw pole motor.It explains how the cogging torque can be produced by the permanent magnet motor and introduces the main calculation method for the cogging torque and the basic method that can reduce the cogging torque in permanent magnet motors.By using the Fourier method,this thesis concludes that the cogging torque of transverse flux motor and claw pole motor can be minimized very low by shifting their permanent magnets with a determined angle.Depends on the material properties of SMC material,this thesis states the most effective method that can reduce the cogging torque for transverse flux motor and claw pole motor,for example the unequal stator claw pole and the segmented PM shifts are the effective ways to minimize the cogging torque in claw pole machine.3.For nowadays almost all the SMC motors using the NdFeB to produce the PM flux linkages which makes the material cost of the SMC motor is very high and confining the SMC motor to be used in the low cost applications,this thesis proposes a soluation that using the ferrite magnet to replace the NdFeB to produce the PM flux linkage in the SMC motor.Considering that both the SMC and ferrite magnet are not the good performance magnetic materials,this thesis investigates the ways to design the magnetic circuit by using these two materials.By comparing the different rotor structures for the claw pole machines,this thesis finds that the claw pole machine with the spoke structure rotor by using the ferrite magnet has the highest performance to cost ratio.This thesis designs a double rotor axial flux machine by using the ferrite magnets and SMC,this motor benefits for the good flux concentrating structure and its magnetic load is comparatively high with the motor by using the NdFeB.This thesis also designs and investigates other motors uing these two cheap materials,such as the axial flux claw pole machine,3D flux transverse flux flux switching permanent magnet machine,3D flux radial flux flux switching permanent magnet machine,and 3D axial radial flux machine.Both these motors have good performance though the cheap and low performance magnetic materials are utilized.This part provides the good solutions for the low cost electrical machine applications.4 For nowadays the optimization of SMC core electric machines has the following confines such as the optimization process need much time and only the electromagnetic performance is considered,this thesis investigates the multilevel optimization method and multidisciplinary optimization method for the SMC motor.5.This thesis investigates the general methods to build the SMC core,studying the best manufacturing method for a determined SMC core for the commercial mass production.This thesis investigates the methods to build the SMC core in the laboratory such as the line cutting and low desnity die pressing,and comparing the benefits and demerits for the SMC core that built by using these two methods respectively.In addition,the detailed manufacturing method for the SMC core by using the manual die pressing and heat treating is presented.