New linear reciprocating machine with stationary permanent magnets

The present paper introduces a new permanent magnet (PM) linear reciprocating machine. The new machine has the PMs on the stator. The flux linkage in the stator coils is reversible to make better use of the stator core. It is essentially a single-phase machine with oscillatory linear motion with linear mechanical springs at the mover ends and working under resonance conditions. The basic configuration, performance, preliminary design equations, and starting transients for motoring are investigated and illustrated by numerical examples. Two identical 125 W machines have been built and back-to-back tested. Characterised by an easy-to-build technology and high efficiency, the new machine holds great potential both as a linear alternator and as a linear oscillomotor for pumps and compressors.