Influence of magnet materials on performances of fault-tolerant permanent-magnet vernier machines

Fault-tolerant permanent-magnet vernier (FTPMV) machine is a new permanent-magnet (PM) brushless machine, incorporating the merits of high torque density and fault-tolerant characteristic. However, the high usage of rare-earth PMs significantly increases the machine cost. In this paper, low cost magnets are employed to reduce the cost of the FTPMV machine. Meanwhile, the influence of PM materials on performances such as back-electromotive force (back-EMF), torque, and cost of the FTPMV machine are investigated and discussed. Based on the analytical results called conformal transformation and the finite element method (FEM), the mechanisation of PM materials influencing the performances of the FTPMV machine are investigated. Finally, a FTPMV prototype with sintered NdFeB is built and tested to validate the theoretical analysis.