Magnets in modern rotary actuators

The principle of operation of most modern rotary actuators is based on permanent magnet-electromagnet interaction to develop electromagnetic torque with limited rotary motion. Because of their simplicity, low cost, and high performance they are finding more and more industrial applications. This paper describes permanent magnet aspects applied to three basic rotary actuator configurations: disc, cylindrical, and claw pole. Although different in shape and magnetization pattern, all magnets feature multipolar structures and are based on high energy magnet materials. Because of the complicated, nonsymmetrical rotary actuator configurations, the magnetic analysis is based on finite element math models. The analysis, which is well supported by test results, is utilized for optimization and parametric study purposes. As a result of our efforts, three different magnet geometries were obtained having different magnetization patterns, which might be applicable for other electromagnetic devices.