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Mitigating noncirculating bearing currents by a correct stator magnetic circuit and winding design," in IEEE Transactions on Industrial Electronics.

Modern converter-supplied AC motors are exposed to bearing currents. Despite extensive research and development, the industry still does not have a final solution with acceptable cost and high efficiency. This paper focuses on capacitive bearing currents. After a brief explanation of the phenomenon, an unconventional approach for effective mitigation of the capacitive bearing currents is proposed. The approach suggests using grounded electrodes in the slot openings to reduce the stator-winding-to-rotor-core capacitance and thereby the bearing currents. Different electrode diameters are considered and evaluated by a FEM analysis. The results are verified by laboratory tests. The bearing voltage ratios of the original and modified induction motor are compared. Index Terms-Ball bearings, electrical discharge machining bearing currents, electrical machines, finite element analysis, induction machines, variable speed drives.

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Power-electronic-converter-induced motor bearing currents are a widespread problem in the field of electrical drives. Parasitic capacitances between the electrical machine's parts provide a path for leakage currents, which finally harm metallic ball bearings. Remembering that end-windings have a significant contribution in building up stray capacitances, a countermeasure affecting both the lamination stack and end winding areas is needed. This paper focuses on a countermeasure against the non-circulating bearing currents in the cluster of solutions at the motor side. Electrostatic shielding approach, which is a known principle to reduce capacitive couplings, is applied in electrical machines every now and then. In this work, the principle of slot-embedded grounded electrodes is extended to cover also the end-windings. Thus, the electrodes provide a better shaft-to-ground voltage mitigating effect compared to the case where electrodes are applied only in the lamination stack area. The feasibility and effectiveness of such a countermeasure are investigated. Different options in terms of scaling of both the machine size and diameter of the electrodes were analyzed and corresponding conclusions were pointed out.

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The paper considers a fundamentally new installation for the processing of a droplet-air environment in a non-equilibrium plasma. Its various designs are presented. This installation is built on the basis of pulsed energy devices and is intended for water disinfection and decomposition of dissolved organic compounds, the production of nanomaterials, research in physics and chemistry, etc. We have conducted research of the performance and energy efficiency of this method of processing. It is established that in obtaining the target product, this method of processing has an advantage over the known methods: due to high performance and energy efficiency, as well as the simplicity of this processing method. In addition, the parasitic load capacity of the nanosecond generator is reduced several times, this fact increases the voltage rise rate on the cells of the plasma plasmatrons, which improves performance and energy efficiency.