Integrated radial and dual axial-flux variable-reluctance vernier machine

Variable reluctance vernier machines, without any permanent magnets, can be driven by typical three phase voltage source inverters and can generate higher torque than other variable reluctance machines due to the magnetic gear effect. Nevertheless, conventional variable reluctance vernier machines have less torque density compared with permanent magnet machines. Therefore, we have proposed an integrated radial and dual axial-flux structure to improve the torque density and evaluated its performance using finite element analysis. Additionally, we have designed a miniaturized machine due to multipolarization and evaluated its performance. The proposed machine increased the torque density as 68% with compared to the conventional variable reluctance vernier machine with a single rotor. This paper describes the designs and torque performance of two proposed machines and two other machines, single- and dual-rotor machines, for comparison.