Electromagnetic Characteristics Analysis of a Tubular Moving Magnet Linear Generator System

As a new type of advanced electrical power generation system, free-piston engines can be applied to many fields, such as electric vehicles and communication base stations. In this paper, a novel tubular moving magnet linear generator system is designed for free-piston engines. A three-dimensional finite element model of the designed linear generator is presented using a transient computing method with a motion solver. The electromagnetic force, electromotive force, and generating efficiency of the designed linear generator are analyzed in detail. A prototype is manufactured and tested under laboratory conditions, and then the main performance of the prototype is evaluated using the validated finite element model. The electromagnetic analysis in this paper indicates that a generating efficiency of 91.4% can be obtained by the moving magnet linear generator under the rated working frequency of 50 Hz. Compared with the existing moving coil linear generator prototype, the power volume density and the power mass density of the new designed moving magnet linear generator prototype are increased by 150% and 35%.