Daisuke Muto, Keisuke Ikeda, Keiichi Tomizawa, Hideo Fukuda, Masahiro Kozako, Masayuki Hikita


Since the design of motors of the xEV (electric cars) has been accelerating to be smaller in their size and larger in their output power to improve the driving performance and the fuel efficiency, the winding wire applied to the motors is required to have an insulating coating with a higher insulation performance. Furukawa Electric investigated to improve the Partial Discharge Inception Voltage (PDIV) and developed the insulation with a remarkably enhanced PDIV and a low permittivity by introducing micro cavities into the insulation coating. We tested the influence of the mechanical stress and the wave form of the applied voltage on the partial discharge performance of the winding wire utilizing the enamel coating containing micro cavities. When the wire was elongated on the assumption that the wire was winding during coil manufacturing, it was demonstrated that the PDIV kept a proper performance, according to the result. When the impulse voltage was applied, the PDIV was higher compared to the application of the utility alternating current frequency and the phenomenon was explained by the Volume-Time theory.

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