Augmentation of passive magnetic bearing performance by using air or iron intervals

Purpose This paper aims to suggest the use of air or iron intervals between axially magnetized rings to increase the forces and stiffness of permanent magnet passive magnetic bearings (PMBs). The paper calculates the stiffness of such bearings through an analytical method and optimizes the dimensions of the magnets for achieving maximum stiffness. Design/methodology/approach For determining the magnetic fields distribution, forces and stiffness of the bearings, a 2D analytical method is used, based on the subdomain method. For the sake of generalization, all of the parameters are normalized and optimized for maximum normalized stiffness per magnet volume ratio. Findings The optimum sizes of the magnets as well as the optimum dimensions of the air or iron intervals are calculated in this paper. The optimum sizes of the magnets are around the air gap length and it is very difficult to realize them. Using iron intervals can improve the stiffness to the extremely high values in practical dimensions of the magnets. Originality/value This paper presents a novel configuration for improving the performance of PMBs with alternately axially magnetized rings.

An Analytical Expression for Magnet Shape Optimization in Surface-Mounted Permanent Magnet Machines

Surface-mounted permanent magnet machines are widely used in low and medium speed applications. Pulsating torque components is the most crucial challenge, especially in low-speed applications. Magnet pole shape optimization can be used to mitigate these components. In this research, an analytical model is proposed to calculate the magnetic vector potential in surface-mounted permanent magnet machines. A mathematical expression is also derived for optimal the magnet shape to reduce the cogging torque and electromagnetic torque components. The presented model is based on the resolution of the Laplace’s and Poisson’s equations in polar coordinates by using the subdomain method and applying hyperbolic functions. The proposed method is applied to the performance computation of a surface-mounted permanent magnet machine, i.e., a 3-phase 12S-10P motor. The analytical results are validated through the finite element analysis (FEA) method.

A special variant of the subdomain method for solving the Fredholm integral equations of the second kind

Предложен и теоретически обоснован специальный вариант метода подобластей на базе полиномов Канторовича приближенного решения интегральных уравнений Фредгольма второго рода в пространстве гладких функций. A special variant of the subdomain method based on Kantorovich polynomials is proposed and theoretically substantiated for the approximate solution of Fredholm integral equations of the second kind in the space of smooth functions.

Magneto-mechanical analysis of magnetic gear pole pieces ring from analytical models for wind turbine applications

This article deals with the structural behavior of a multi-bar system which maintains pole pieces in a concentric magnetic gear. Simplified analytic magnetic and mechanical models of the system are proposed in order to be integrated in a multi-criteria global optimization for the sizing of a magnetic gear in wind power applications. For this purpose, the reduction of the computation time is taken into account. The geometry of the support bar subsystem is defined and a Q bar structure is proposed. The magnetic study is based on Maxwell’s equations and subdomain method in order to determine variable radial and tangential magnetic loads. The mechanical study is based on a multibody model with different bars stiffnesses which are determined from a one-dimensional model. Variable radial and tangential magneto-mechanical pole pieces loads (magnetic load and weight) are also considered. An example of a magnetic gear with 172 pole pieces (i.e. 6-MW wind turbine) is proposed to analyze the mechanical behavior and also the computation time.