http://hdl.handle.net/10397/932 Search the Channel search http://repository.lib.polyu.edu.hk/jspui/simple-search http://hdl.handle.net/10397/1210 Title: A 3-D study of eddy current field and temperature rises in a compact bus duct system<br/><br/>Authors: Ho, Siu-lau; Li, Y.; Lin, X.; Wong, Ho-ching Chris; Cheng, K. W. Eric<br/><br/>Abstract: In this paper, a three-dimensional eddy-current field model for calculating the eddy-current losses in a compact bus duct system is proposed. The temperature rises in the compact bus duct system, including both the long linear section and connecting unit, are evaluated using finite-element method when solving the governing thermal equations. The contact resistance between copper conductors and the corresponding temperature rises are measured in the test also. The computations are validated by test results and the results confirm the proposed algorithm is accurate and practical. http://hdl.handle.net/10397/1199 Title: Solution of a 3-D complex finite element model of skewed rotor induction motors using an iterative method<br/><br/>Authors: Ho, Siu-lau; Fu, Weinong; Wong, Ho-ching Chris<br/><br/>Abstract: One of the difficulties of the three-dimensional (3-D) eddy current finite element methods is to solve large finite element equations economically. In this paper a 3-D eddy-current finite element model using a four component formulation of complex variables to study skewed rotor induction motors is described. An iterative process among the four specific components during the solution of large algebraic equations is presented. The proposed method overcomes the non-convergence problems when the ICCG method or the shifting ICCG method is used directly. The algorithm also requires much less computer storage compared with the Gaussian elimination method. http://hdl.handle.net/10397/1168 Title: Numerical analysis of thin skin depths of 3-D eddy-current problems using a combination of finite element and meshless methods<br/><br/>Authors: Ho, Siu-lau; Yang, Shiyou; Ni, Guangzheng; Wong, Ho-ching Chris; Wang, Yuhuai<br/><br/>Abstract: To alleviate the difficulties encountered in the generation of meshes for the finite element method for solving thin skin depth problems involving three-dimensional (3-D) eddy-currents, particularly hi cases in which the eddy-current region is only a fraction of the entire domain, a new technique based on the combination of finite element and meshless methods is proposed. The use of numerical approach to uphold the mathematical properties of the combined shape functions in terms of consistency and linear independence is also investigated. It is shown that a very coarse mesh is already sufficient to give accurate numerical results with the proposed algorithm. To validate and demonstrate the advantages of the proposed method, typical numerical results on studies of high-frequency 3-D eddy-current problems are reported. http://hdl.handle.net/10397/1166 Title: Novel approach to circuit-field-torque coupled time stepping finite element modeling of electric machines<br/><br/>Authors: Ho, Siu-lau; Li, H. L.; Fu, Weinong; Wong, Ho-ching Chris<br/><br/>Abstract: This paper presents a sub-block algorithm for the time stepping finite element solution of problems in which sets of electromagnetic field equations, circuit equations and mechanical equation are coupled together. The proposed method ensures that identical solutions are obtained for the sub-blocks by controlling the step size of the time stepping process. This new method simplifies the process of dealing with coupled-system problems and it also greatly reduces the computation time. A time stepping finite element model of an induction motor is used to demonstrate the proposed method in details.