Comparative analysis of a spoke ferrite permanent magnets vernier synchronous generator

The paper analyzes the performance of vernier synchronous generators as compared to synchronous generator, both with spoke ferrite permanent magnets and outer rotor. An existing wind turbine synchronous generator of 3 kW / 350 rpm with internal rotor and surface NdFeB permanent magnets was taken as a reference. A semi-analytical multiphysics design optimization methodology, employing a deterministic algorithm, was used to minimize the mass of generator active materials. Reluctances magnetic equivalent circuits were used to obtain the electromotive force and inductances. The results show that the vernier machine has a higher power density with less torque ripple and lower cost of active materials than the corresponding synchronous one. When compared to the NdFeB magnets reference machine, the vernier generator with spoke ferrite magnets has a significantly lower cost of active materials and a slightly higher power density. A finite elements software was used to validate the results.