Internal rotor airgap-less electric motors

This paper proposes a new family of electric motors based on the concept of an airgap-less device with an internal rotor. The internal flux and therefore electromagnetic torque is maximized because the rotor is allowed to touch the stator. The proposed family of motors are competitive in applications where hydraulic motors are prevalent, i.e., low-speed and high-torque requirements. Furthermore, the proposed motors present the following advantages over hydraulic motors: (1) higher efficiency, (2) lower number of energy conversion stages, and (3) converts electrical energy directly to mechanical energy with no extra braking system. The modeling, simulation and experimental validation are presented in this paper as well. A proof-of-concept electric motor with six magnetic poles is built to validate the theoretical assumptions.