Design and analysis of an axial flux induction machine with uniform airgap flux density using multi slice approach

Abstract

newline In axial flux machines, the flux flow in axial direction whereas in radial flux machines the flux flows in radial direction. Axial flux machines (AFMs) are widely used as hub type motors and direct drive applications. The AFM occupies lesser volume as its axial length is lesser than the diameter of the machine. The torque density of axial flux machines is higher than its radial counterpart. Though the axial flux machines have several advantages than radial flux machines (RFMs), it has lamination complexity and unequal airgap flux density. The axial flux machines have varying geometry along radial direction. Hence it has unequal airgap flux density distribution along the radial direction. There are several types of axial flux machines among which axial flux induction motor (AFIM) is considered in this thesis for design and analysis. For the comparison of axial flux induction motor and radial flux induction motor, the design parameters and performance parameters have to be determined. The design of AFIM considering average radius of the machine is developed in this thesis. This design is similar to conventional design procedure used for radial flux induction motor. Based on the conventional design approach of AFIM, the AFIM with open type slot is designed. In the one to one comparison of both the machines, the determined magnetic circuit and performance parameters are compared for various values of design parameter k . In the comparison, the airgap volume of both machines is considered to be same. The parameters obtained from average radius model of AFIM are not similar to actual machine parameters as the AFIM has varying dimensions from inner to outer portion along radial direction. Hence multi-slice analytical approach is proposed to determine the exact magnetic circuit parameters and flux density distribution of the machine. The actual B-H characteristic of the material is considered while evaluating the magnetic circuit parameters of the machine.