Novel linear tubular brushless permanent magnet motor

There is an increasing requirement for controlled linear motion over short and long strokes, in the factory automation and packaging industries, for example. Linear brushless PM motors could offer significant advantages over conventional actuation technologies, such as motor driven cams and linkages and pneumatic/hydraulic rams-in terms of efficiency, operating bandwidth, speed and thrust control, stroke and positional accuracy, and indeed over other linear motor technologies, such as induction and switched reluctance motors. A novel form of linear tubular brushless permanent magnet motor has been developed. The paper describes the principle of operation, alternative topologies of the motor, and potential applications; discusses the main design considerations, such as the back-EMF waveform and the cogging force; and compares finite element predictions and measurements.