Hierarchical thermal network analysis of axialflux permanent-magnet synchronous machine for electric motorcycle

A novel 24 kW 12-slots/10-poles axial-flux permanent-magnet synchronous machine (AFPMSM) with external rotor motor applied to the large electric motorcycle is introduced in this study, which has the characteristics of the yokeless and segmented armature for power density improvement. The hierarchical method is used for calculation of stator iron core loss based on the analytical solution of air-gap flux density, which cuts the prototype into many equivalent linear motor slices in the circumferential direction. A major advantage of hierarchical methods over traditional iron core loss calculation is its higher accuracy and rapidity. Then a lumped parameter T-type thermal network model is presented for AFPMSM temperature rise calculation. A 3D liquid-solid coupling model is compared with the 2D T-type lumped parameter thermal network. Finally, a temperature rise measurement platform is established to verify the above-mentioned methods. Testing result shows that the hierarchical method and T-type thermal network have a higher accuracy to predict each part temperature.