Linear Motors – Dr. Renato Lyra, Aerotech

Electric drive systems are an essential part of any high performance and high precision motion system. A major advantage of using electric drive systems is the simplicity of dealing with electrical energy. Since electrical signals can be easily shaped, controlled and distributed, their use provides a degree of simplicity, flexibility and performance not present in other types of actuators. An electric drive system is typically composed of a controllable and/or programmable power supply, electric motors or actuators and sensors. Both rotational and linear motion can be directly obtained without the need of mechanical converters. This tutorial is focused on one of the components of the electric drive system: motors and actuators. A good understanding of the basic principles that govern the operation of
electric motors and actuators is fundamental to the specification and design of motion systems.

This tutorial is structured into four parts. The first part covers the basics of electromechanical energy conversion using rotary and linear motors. A summary of the key quantities used when working with electric motors is presented, followed by a discussion on how to convert electrical energy into mechanical energy. Part two introduces the most common motor types and the materials used to build them. Permanent magnet materials, magnetization, demagnetization and temperature effects are some of the topics covered in this part. Part three focuses on one specific type of electric motor: the Permanent Magnet Synchronous Motor (PMSM). Both linear and rotary motors are discussed since they share the same working principles. Additionally, the main specification constants are explained. Finally, part four presents some particularities of linear motors, such as end effects, magnet track shape and cogging
reduction.

This tutorial makes use of graphics, diagrams and finite element representation to facilitate the comprehension of each aspect presented. Audience interaction is encouraged during the presentation.

Dr. Renato Lyra, Aerotech

Renato Lyra (IEEE M’08) received his B.S. and M.S. degrees from the Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil, in 1991 and 1994 respectively, and his Ph.D. degree from the University of Wisconsin, Madison, USA, in 2002. He was a faculty member at the Department of Electrical Engineering at UFMG for 15 years. In 2009 he joined Aerotech, Inc. in Pittsburgh, PA, USA, as Senior Motor Design Engineer. His research interests include permanent magnet motors, both rotary and linear, linear actuators, non-conventional motors and motion control systems.