Hybrid analytical model for air‐gap magnetic field prediction of surface‐mounted permanent magnet motors with a quasi‐regular polygon rotor

Abstract

In this article, a hybrid analytical model for a quasi‐regular polygon rotor (QPR) is proposed. It mainly uses the subdomain method and conformal mapping to solve a non‐circular boundary in the QPR. Firstly, the subdomain method combined with an equivalent surface current method is used to calculate the air‐gap magnetic field considering a slotted stator with a circular rotor. Secondly, by segmenting the non‐circular boundary in the QPR, the complex relative air‐gap permeance of the QPR can be calculated using the conformal mapping. Thirdly, this complex relative air‐gap permeance modifies the air‐gap magnetic field calculated in the first step to obtain the actual magnetic field distributions. Consequently, no‐load and loaded air‐gap flux densities, back‐electromotive force and torque can be obtained. A 12‐pole/3‐phase permanent magnet motor is modelled using the proposed hybrid analytical model, which is validated by finite‐element analysis and experiment. This proposed hybrid analytical model presents a new way of processing the QPR. Its calculation speed is nearly 50 times faster than the finite‐element analysis, which is of great help to the initial design and optimisation of machines with QPRs.

Noise and vibration modelling of Permanent Magnet Synchronous Motors - a review

“…The method considers the slotting effect and a relative permeability of the iron as function of the local flux value. Chen et al [65] combine the usage of subdomain techniques and CM in order to overcome problems given by quasi-regular polygon rotors, causing non circular boundary in surface permanent magnets motors. The combination of these methods leads to accurate results compared with both Finite Element Analysis (FEA) and experimental data, thus taking advantage of the reduced computational time, as outlined in the above papers.…”