Winding Design And Magnetic Steel Optimization Of Axial Flux Permanent Magnet Synchronous Coreless Motor Based On PCB Technology

As a type of axial flux permanent magnet motors(AFPM),disc coreless motor possesses many merits including high power density,high efficiency and short the length of motor axis.The application of the coreless structure ensures a significant reduction of the weight of motors,which benefits the low speed operation performance of disc coreless motor.Axial flux coreless permanent magnet motors usually adopt wound-rotor structure,which leads to problems including the difficulty of installation,descend of location precision,sometimes even leads to vibration of stator along axis.PCB-based AFPM,on the other hand is superior to wound-rotor based structure in that it effectively avoids magnetic hysteresis loss and eddy current loss caused by the core,eliminates cogging torque ripple,and raises the power density of the motor.The application of PCB technology enables the simplification of manufacture process of armature,reduces the weight of the motor,impacts the axial space of the motor,makes the location of the coil more precise,and benefits large scale manufacture.Meanwhile,rotor magnetic steel of axial flux coreless permanent magnet motor adopts Halbach array,which makes major improvements in both the amplitude and sine feature of air gap flux density as well as the output performance of axial flux coreless permanent magnet motors.Aiming at maximizing the power density of PCB-based axial flux coreless permanent magnet motors,this paper designs a novel distributed PCB wounding,and carries out a comparision with concentrated PCB stator wounding structure.Taking multipal elements including output back EMF,power density,and wounding loss into consideration,an analysis about the features and advantages of the novel distributed PCB wounding is carried out.Considering the features of PCB axial flux coreless permanent magnet motor,a novel topology of Halbach array is proposed,whose rotor structure adopts the proposed topology.Taking the pole angle parameters at the inter radius and outer radius pole as independent variables,the shapes of main magnet pole and auxiliary magnet pole of fan-shapes with different centres of circles are optimized,thus making their distributions on the magnet steel more reasonable.In the premise that the consumption of permanent magnet stays unchanged,namely the cost of a motor doesn't increase,optimization of the performance of PCB stator axial flux coreless permanent magnet motor is realized.Finally,finite element simlation is carried out,and the simulatioin results is consistent with theoretical analysis.This paper provides guidance for the design and research of PCB stator axial flux coreless permanent magnet motor.