Contents I. Introduction
IN recent years, due to the booming direct-drive applications, such as wind power, electric propulsion, etc., low-speed high-power electrical machines are attracting more and more attention. However, the low speed and high power demand makes direct-drive machines suffer from bulky size and large material consumption. Therefore, researchers have mostly concentrated on high-torque-density electrical machines, and many novel high machine topologies with high torque density are proposed during the past couple of years.
