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The development of high-frequency pulsewidth-modulation-based adjustable-speed drives (ASDs) has increased the efficiency, performance, and controllability in induction motor applications. However, the high switching frequencies and the faster switching times of insulated gate bipolar transistors (the device of choice in these ASDs) introduce disadvantages like overvoltages at the motor terminals when long cables are used between the drive and the motor. Another industry-wide concern is the generation of rotor shaft voltage and the resulting bearing current. The grease film in a bearing acts as a capacitor that charges due to the transitions in the common-mode voltage imposed at the motor terminals by the drive. The breakdown of the film causes a spike of current to flow that can damage the bearing and reduce life. A significant amount of effort has been directed at understanding the shaft voltage phenomenon and the associated bearing current. This paper attempts to develop circuit models to predict the level of the shaft voltage. The circuit models can then be used to predict the shaft voltage levels at different installations, using simulation software like PSpice. Circuit models for two specific motors are developed. The predicted shaft voltage is very close to the actual voltage levels seen on the shaft when the motors are operated by ASDs. Index Terms--Bearing current, circuit model, motor parasitic impedance, shaft voltage.

In this paper, the penalized H-formulation, which has been shown by recent research as a promising alternative to vector potential methods, is implemented for simulating 3D time-harmonic eddy current diffusion. Compared to a rigorous time-stepping approach, the present nonlinear time-harmonic FEM procedure can predict global time-average forces and losses with acceptable engineering accuracy, and yet at much reduced computational cost. The procedure is validated with examples involving linear and nonlinear conductors. Index Terms - Eddy currents, nonlinear magnetics, harmonic analysis, finite element methods.

'Edge' element has become an indispensable tool in the h-version FEM for high-frequency electromagnetic problems. To investigate a p-method based on this technology, hierarchic higher-order 'edge' elements are desirable. In this paper, we establish such families of 3D elements by mixing the 'edge' element basis and the hierarchic p-shape functions. These elements are then employed in modal analysis of electromagnetic cavities.

In this paper, we discuss the frequency-domain FEM computation of antenna input impedance using curved, mixed-shaped 'edge' elements. The antenna feed is treated as a waveguide and is included as part of the model. The feeding waveguide is truncated with a first-order absorbing boundary condition and the solution domain with a second-order condition. A monopole antenna on top of a conducting box is analyzed and good impedance results are obtained.

This paper presents a unified approach for magnetic-circuit coupled problems in 2D and 3D. The approach is based on the [right arrow A]-V formulation with the Coulomb gauge for low frequency eddy currents, and the modified nodal analysis method for electric circuit simulation. It supports static, time-harmonic and transient analysis types. Both stranded coils without eddy currents and massive conductors with eddy currents are included. Compared to other methods, the present approach can be easily implemented in existing finite element electromagnetic codes. Numerical examples are presented to validate the theory.

In this paper, we present a time-domain solution to 2D TM/TE electromagnetic scattering problems using the finite element method. We implement Barry-Bielak-MacCamy (BBM) time and space local absorbing conditions on a curved convex truncated domain boundary. The BBM boundary conditions, which encompass the popular Bayliss-Turkle mode annihilating boundary conditions and Kriegsmann on-surface boundary conditions, yield symmetric second order systems, which are then integrated using Newmark's schemes. Numerical examples are provided and validated against published data. The method can be in principle extended to 3D transient scattering.

The paper discusses efficient electrostatic field solutions techniques to simulate micro electro mechanical systems (MEMS): adaptive p-elements to remove the burden of manual mesh refinement; hybrid finite elements-Trefftz formulation to treat open boundary problems; energy based capacitance matrix and lumped capacitance value extraction. Index Terms--Capacitance, finite elements (FE), hybrid FE-Trefftz, micro electro mechanical systems (MEMS), p-elements, Trefftz.