Analytical investigation of air-gap flux density distribution of a PM vernier motor.

This paper presents an analytical method to calculate the air-gap magnetic flux density distribution of a permanent magnet (PM) vernier motor. For this purpose, the air gap permeance, the magneto-motive force (MMF) of rotor magnets and the MMF from stator winding are respectively expressed in the form of Fourier series. The permeance function whose values of the all harmonics are given in terms of geometry, is utilized with the MMF of PMs to analyze the air gap flux density of the vernier machine. In addition, the role of each harmonic components of flux density in the production of back electromotive force (back-EMF) and torque is examined. Finally, the effectiveness and accuracy of the derived expressions are checked with the help of finite element (FE) analysis. [ABSTRACT FROM AUTHOR]