Linear oscillatory electric motor/generators: an overview

Linear oscillatory motion is present in many industrial processes/devices such as: free-piston air compressors, Stirling engines, wave-energy generators, microphones and loudspeakers, ICE valve actuators, etc. Direct drives for such applications based on linear oscillatory 1(3) phase motor/generator (LOM/G) have been developed now for decades to produce higher energy efficiency per given mission profile, with precision power electronics control. Recent progress on LOM/Gs 1(3) phase for constant (resonant) and variable oscillation frequency, with and without PMs, with and without mechanical springs (to boost output and efficiency), including topologies with superhigh thrust density based on magnetic lead screw principle, is discussed in the present overview paper, from competitive topologies and modeling to performance assessment, design, and control, with representative results from the literature.