Recent development of linear machine topologies and applications

Linear machines (LMs) produce linear motion without any intermediate transmission mechanisms, thus the whole electromechanical system has simple structure and its efficiency is high. Because of such merits, linear machines have been studied for a long time and rapidly developed in recent years. Due to the characteristic of open structure, linear machines have more diversity than rotary machines in terms of machine topologies. Accounting for the wide applications of linear machines, e.g. Maglev train, precision machine tools, semiconductor processing device, automatic equipment, logistic transport line, ropeless lifter, compressor, etc., this paper reviews the most applied linear machines including machine topologies, operating principle and features. In addition, the influence of end effects and the corresponding reduction methods are also summarized. Finally, several commercial applications are exemplified.