Fabrication of variable frequency motors using polyester-imide-hybridized resins and hyperbranched polysiloxane coated nano-TiO2

Abstract

The key for fabricating variable frequency motors is to develop high-performance resins that not only have excellent corona resistance and high breakdown strength, but also are suitable for vacuum pressure impregnation (VPI) technique; however, few resins simultaneously possess these features. Herein, a series of unique hybridized resins based on polyester-imide resin (EPEI) and hyperbranched polysiloxane coated nano-TiO2 (HSi-TiO2) were prepared, and their structure, processing characteristics, corona resistance, and high breakdown strength were investigated systematically. Results show that EPEI/HSi-TiO2-hybridized resins have excellent storage stability and are suitable for VPI, completely overcoming the disadvantages of traditional nanofiller-modified resins. In addition, the presence of HSi-TiO2 changes the microstructure of crosslinked network, endowing EPEI/HSi-TiO2-hybridized resins with outstanding corona resistance, high breakdown strength, and remarkably decreased partial discharge. The maximum corona--resistant life is 1586 min, about 57 times that of EPEI resin. As the content of HSi-TiO2 increases, the breakdown strength of the hybridized resin increases, and the maximum value is 28.1 kV/mm, 15.2 % higher than that of EPEI resin. These attractive performance characteristics demonstrate that EPEI/HSi-TiO2-hybridized resins have great potential in fabricating variable frequency motors and high-performance electric equipments. The origin behind these attractive performance characteristics possessed by EPEI/HSi-TiO2-hybridized resins was intensively discussed.