Design and analysis of a new parallel-hybrid-excited linear vernier machine for oceanic wave power generation

This paper presents a parallel-hybrid-excited linear vernier machine (PHE-LVM) for direct-drive oceanic wave power generation. By equipping a set of field winding in the mover yoke, hybrid excitation for the proposed PHE-LVM is realized: the air-gap flux can be flexibly controlled via adjusting the magnitude and polarity of the DC current in the field winding. With this merit, the operating performances in the wave power generation, such as the output voltage, load capacity and power factor can be improved. Firstly, the proposed PHE-LVM topology based on homopolar machine configuration is presented, with the consequent-pole PM poles mounted on the surface of the stator, while the DC field winding is wound around the mover yoke. Secondly, the operating principle of the proposed PHE-LVM is described with corresponding theoretical analysis. Thirdly, by using the 3-D finite element method, the power generation performances of the proposed PHE-LVM are evaluated. Finally, a prototype machine is also implemented and tested. Experimental results well agree with the analytical data.