Analytical Design of Coreless Axial-Flux Permanent Magnet Machine With Planar Coils

This paper presents the design of an axial-flux permanent magnet (AFPM) generator with two rotors and one coreless stator with planar coils. This geometry has reduced the total mass of the generator and production demands of the machine. The geometry of the coreless AFPM machine enables direct analytical calculation of the magnetic field in the air gap. The analyzed geometry is reduced to the equivalent 2D model. The equivalent circuit parameters are evaluated for the proposed design of the planar coil by the calculation of the magnetic field produced by permanent magnets and stator winding separately. These principles of analytical design of the AFPM machine are integrated into the developed software "deSAX". The presented analytical approach and the results are validated by 3D finite-element analysis (FEA). The generator is then produced and tested under the off-grid operation and the maximal power 200 W (750 rpm) is obtained according to calculated output characteristics.