Boosting Power Density of Electric Machines by Combining Two Different Winding Types

Abstract

Abstract: This paper presents a novel magnetic circuit and winding design for extreme lightweight and high torque permanent magnet electric machines. Therefore, two different types of winding are combined to boost torque sharing the same magnetic circuit. One is an air gap winding, which is mounted directly on the back iron of the stator surface using the magnetic flux field in the air gap to generate Lorentz forces acting on the winding and providing one part of the torque. The other one is a slot winding, which is fixed inside small slots of the stator back iron generating magnetic forces and contributing the second part of the torque. Overall, only a small amount of iron is necessary for this novel magnetic circuit design. This results in an extreme lightweight, efficient, dynamic and high torque electrical machines for a wide range of use in mechatronics. The paper gives a design example of a wheel-hub-motor for a passenger vehicle with an extraordinary power-to-weight-ratio.