Thrust Performance Improvement of Field-modulated Hybrid Excitation Permanent Magnet Transverse Flux Linear Generator Based on Partitioned Staggered Translator

Recently, linear generators have been implemented in direct drive wave energy conversion (DD-WEC), thus simplifying the structure and improving system efficiency. Since DD-WEC is a typical low-speed application, linear generators with multi-pole design all encounter problems such as low power density and low efficiency. Similar to the magnetically geared machine, field-modulated permanent magnet transverse flux linear generator (FM-PMTFLG) has been a suitable candidate for DD-WEC, due to the high power density capability ensured by the ‘magnetic gear effect’. However, for solely PM excited generators, there is a tradeoff between high power density and wide speed operation. Hence, field-modulated hybrid-excitation permanent magnet transverse flux linear generator (FM-HE-PMTFLG) is proposed. In order to improve the thrust performance, the partitioned staggered translator (PST) topology is introduced. The simulation results show that PST topology can achieve better thrust performance than partitioned translator (PT) counterpart. Compared with PT topology, PST topology reduces the magnetic flux leakage and has advantages of higher thrust density, less thrust ripple, higher flux linkage and better total harmonic distortion (THD) of back-EMF.