Airgap-less electric motor: A solution for high-torque low-speed applications

This paper proposes a new category of electric motors able to generate high torque with reduced volume, i.e., high torque density. Such a new design is denominated as an airgapless electrical motor since the rotor touches the stator as it spins. Due to its zero airgap, the proposed motor will maximize the generated torque, allowing such type of motors to be competitive in applications where hydraulic motors are prevalent, i.e., low-speed and high-torque requirements. Unlike hydraulic motor systems that face two major problems with their braking system and also with low efficiency due to a large number of energy conversion stages (i.e., motor-pump, hydraulic connections and the hydraulic motor itself), the proposed electric motor converts electrical energy directly to mechanical energy with no extra braking system necessary and with higher efficiency. A proof-of-concept electric motor prototype along with its drive system is built to validate the theoretical assumptions proposed in this paper.