A new design method for topology and shape optimization to preserve high-voltage systems is proposed. The level set technique for the topology optimization is employed with the finite-element method. For the velocity field in the level set equation, the continuum sensitivity formula is used for accurate information of the electric field effect on the topology and shape variation. This technique is applied to three practical examples and the optimum designs of insulating dielectric for the systems are obtained. The optimum designs could suppress troubles, such as thermal deterioration or electrical breakdown, in the systems.Index Terms-Design optimization, finite-element methods, high-voltage system, level set method, sensitivity analysis.

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This paper presents a low frequency eddy current method to estimate internal deep defects in ferromagnetic material. A magnetic system for an exciting field is designed to generate sufficient coil flux to enhance sensitivity and to make certain of signal linearity. The existence and shape of a defect can be recognized by observing the difference in variation of the equivalent impedance. Magnetic systems with various interior deep defects are numerically analyzed by finite element method and their data is compared with those of experimental systems. The measured data of the impedance variation are distinguishable enough to be used to estimate the existence and shape of defects in the steel structure.Index Terms-Eddy current testing, ferromagnetic materials, finite element methods, low frequency, magnetic sensor.

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In this paper, hole sensitivity formula is analytically derived for topology optimization in magnetostatic system. With the concept of virtual hole, the hole sensitivity is obtained using continuum shape sensitivity. To demonstrate the validity of the hole sensitivity, topology optimization of synchronous reluctance motor is tested. Since the hole sensitivity formula is represented only with electromagnetic field, it is easily implemented for topology optimization.