Fast Approach to Predict the Airgap Magnetic Field of a Permanent Magnet Vernier Machine

This paper aims to determine the airgap magnetic flux density of a surface-mounted Permanent Magnet Vernier Machine (PMVM) by considering both rotor and armature Magneto-Motive Forces (MMFs). The calculation method relies on permeance and MMF concepts to predict the mid-airgap flux density. Two Magnetomotive-Permeance Function (MMF-PF) methods are applied and compared: the first one is based a predefine flux lines permeance function model, while the second one employs a conformal transformation approach to evaluate the airgap permeance function. A square waveform is chosen for the MMF in both models. The effectiveness of these methods is assessed using Finite Element Analysis (FEA), focusing on an outer rotor PMVM as a case study. Results indicate that the first method is more accurate in calculating the armature magnetic field, whereas the second method proves more efficient for predicting the rotor magnetic field. The combined approach leveraging both methods offers a reliable and expedient alternative to FEA, particularly useful during the initial design phases of PMVMs.