Comparative method for twin-rotor PM brushless motors applied as in-wheel motors

A quick, simplified method is proposed to compare the axial-flux and radial-flux twin-rotor PM brushless (TRPMBL) motors, with slot-less stators, for the application of in-wheel motor for the gearless drive of an electric vehicle. This method allows answering which of these two motors with the same magnetic and current loading properties and with the same radius and axial length, when built into the wheel gives greater torque. An expression is derived for the ratio of torques of such motors. To check the validity of this method, the axial-flux and radial-flux TRPMBL motors of the same volume are modeled using FEM and their torques are compared.