I. INTRODUCTION

II. DESIGN METHOD FOR THE CONVENTIONAL AND PROPOSED AFPMSMs

III. RESULTS AND DISCUSSION

IV. COMPARATIVE ANALYSIS OF THE CONVENTIONAL AND PROPOSED AFPM MACHINES

V. CONCLUSION

REFERENCES

This paper presents a comparative performance analysis of 4-kW axial flux permanent magnet synchronous machines (AFPMSMs) with and without a rotor core. The present study is intended for lowspeed applications; however, the investigated machines are designed using an improved diameter-to-length method and their comparative performance is assessed using comprehensive electromagnetic finite element analysis. The results of this analysis suggest that the proposed coreless topology has the advantages of higher output power, higher efficiency, and lower iron or core losses compared to the conventional iron core AFPMSM.

INTRODUCTION

Synchronous machines can be built using a wound rotor structure or a permanent magnet (PM) rotor [1]. Permanentmagnet synchronous machines (PMSMs) tend to be favored over wound rotor synchronous machines (WRSMs) [2] for low-speed applications. PM machines are more efficient than their field-excited counterparts [3], [4] because the rotor field is generated by permanent magnets mounted on the rotor surface rather than a brushed or brushless field excitation circuit [5], [6]. This increases their reliability and reduces their maintenance costs [7], [8]. Permanent magnet synchronous machines (PMSMs) are generally classified into three categories based on the direction of the flux flow: a) radial, b) axial, and c) transverse flux [9]–[۱۱]. In addition to the conventional advantages associated with PM machines, axial flux permanent magnet (AFPM) machines have distinct advantages compared to their counterparts [10], [12]–[۱۵] including a high torque-to-weight ratio, higher power density, higher efficiency, and a more compact structure [16], [17]. These positive features have encouraged researchers to develop new applications for AFPM machines and to make them more compatible with the modern power market [18]. Major applications of AFPM machines include wind power systems, wheel motors, hybrid vehicles, and robotics [19]–[۲۲].