Abstract: The axial flux of the in-wheel motor has the advantages of high power density, high efficiency and short axial length. However, its special 3D structure makes it difficult to concurrently achieve both rapidity and accuracy in electromagnetic design by analytical method or finite element method. In order to reduce the computation efforts while improving the accuracy of results, taking the detailed design of a yokeless axial flux in-wheel motor with amorphous alloy stator tooth as an example, the calculation model of its air-gap flux density is given by combining 3D magnetic field reconstruction method with Maxwell stress tensor method. The calculation formulas for the axial electromagnetic force of lateral rotor and electromagnetic torque are derived, and the waveform of stator magnetic linkage and back electromotive force are analyzed. The results of 3D field reconstruction method are verified by 3-D transient finite element analysis. The results show that 3D field reconstruction method has good accuracy with less calculation time

Key words: axial flux motor, in-wheel motor, magnetic field reconstruction method, Maxwell stress tensor method