The Shell-Like Spherical Induction Motor for Low-Speed Traction: Electromagnetic Design, Analysis, and Experimental Tests

This paper analyzes the electromechanical characteristics of a novel shell-like spherical induction machine with multiple degrees-of-freedom (DOF), formed by a shell stator and a spherical hollow rotor. The shell-like induction machine is evaluated using n-harmonic analytical models for its electromechanical characteristics. The electromechanical model includes the distribution of the copper windings in the stator slots, incorporating the currents harmonic content to describe its spatial distribution. The distribution of the magnetic potential vector and the components of the magnetic flux density are computed using the real source-current distribution. A small prototype was built to validate the analytical model. To do so, experimental tests were done to the magnetic flux density and the torque. The shell-like induction motor is concretized as traction motor in an electric wheel-chair. Its results are compared with a finite-element analysis tool.