In this paper, a coupling of the Finite Element Method (FEM) and the Boundary Element Method (BEM) is used to model the behaviour of magnetoelectric effects in composite structures. This coupling of numerical methods makes it possible not to have to consider a free domain, and thus to use a single mesh for the magnetic, mechanical and electrical problems. This results in a consequent reduction of the number of unknowns which is accompanied by shorter computation times compared to a classical FEM approach. A mixed magnetic vector potentialreduced magnetic scalar potential formulation is used for the magnetic problem, and classical FEM formulations are used for electrical and mechanical problems. The resulting global algebraic system is solved by a block Gauss-Seidel solver.
When the power transformer is energized under no-load conditions, the residual flux will accelerate the saturation of the core, and generated magnetizing inrush current will cause many harms to the power grid. To determine the residual flux in the transformer core with a closed magnetic circuit structure, this paper proposes a method for measuring the residual flux of the transformer based on the phase difference between the test voltage and the transient current. The finite element method is used to model and analyze the core to be tested and obtain an empirical formula for calculating the based on the simulation results. Finally, an experimental measurement platform was built, and the measurement results verified the feasibility and accuracy of the proposed method.
This paper proposes a novel high-speed axial flux permanent magnet synchronous motor (AFPMSM) using hybrid permanent magnets (PMs) to reduce the magnet cost and torque pulsation. Based on a previously reported model with sinusoidal NdFeB PMs, the proposed model is designed with an equal arrangement of ferrite and NdFeB PMs, wherein the hybrid PMs are parallel and vertical to the magnetization direction of the PM. Therefore, three kinds of hybrid PM configurations are adopted for the proposed model. The analysis by the magnetic circuits is firstly carried out. And then the optimal PM configuration for the proposed model is obtained by comparing the electromagnetic performance with the aid of the finite element method.
Magnetic manipulation is a method used for biomedical applications to remotely control micro-robots in a contactless manner. The electromagnet manipulator should control a magnetic field with 3 degrees of freedom inside a region of interest. In various case studies, this field is the result of the superposition of three decoupled uniform magnetic fields. Each of them is individually generated by a different pair of Helmholtz coils. Such arrangement requires the pairs to be nested within each other, inevitably reducing the size of the working area, degrading the performance and the integration of the whole system. The proposed work aims to design a novel electromagnetic manipulator with the help of computational design, to explore beyond the Helmholtz coils arrangement. A topology optimization framework is developed for this purpose. It investigates the distribution of coils that achieves the largest working area, while keeping the different degrees of freedom balanced.
In practice, due to the difficulty in obtaining the precise probability distributions of the uncertain variables, the stochastic reliability-based design optimization (RBDO) methods can hardly be effective in various cases. On contrary, the variation intervals of the uncertain parameter can be relatively easily achieved. In terms of this condition, an efficient sequential optimization and reliability assessment method of decoupled scheme is developed in this paper for the non-probabilistic RBDO (NRBDO) of electrical machines with interval uncertainty.
