Analysis of claw-pole rotor brushless machine with DC excitation by lumped-parameter magnetic circuit model

Nowadays, the replacement of rare-earth permanent magnet is one of the primary targets to enhance the cost-effective design for electrical machines. A claw-pole rotor brushless machine with DC excitation is desirable as a magnetless machine because it is reliable, low-cost, and does not need slip ring etc. However, the inherent 3D structure makes numerical analysis very time-consuming. In this paper, a lumped-parameter magnetic circuit model is developed to model and design an 18-slot/6-pole claw-pole rotor brushless machine with DC excitation, while its validity is examined by using 3D finite-element analysis. The optimization is also carried out, together with optimal skew and unequal rotor pole thickness.