高频电场下摩擦界面的损伤机制及电蚀防护研究

With the advances of the national energy-efficiency project in motor system，the frequency control technology has been widely applied in industrial equipments, railway cars and electric vehicles. However, the application of frequency controlled power supplies poses additional problems to the reliability of these machines. The bearings in the system was found to be damaged in a short time due to the high frequency shaft voltage which is induced by the converters. Although the electrical damages in bearings, which is also called “electrical pitting”, are known for decades, and the pitting mechanism in the friction interfaces have been well investigated, the electrical conditions used in previous researches were DC or low-frequency AC. Therefore, in this project, the high frequency voltage was used, which has the analogous nature with the shaft voltage in converter driving system. By investigation into the electrical damage behavior of friction interfaces, as well as the breakdown and degradation process of lubricating oils under the applied high frequency electrical field, it aims to elucidate the actual pitting mechanism of rolling bearings in frequency controlled driving system. Then, from the point of lubricants, through the compositional design in lubricants, the solutions with combined performances of friction reduction and protection against electrical damage are expected to be developed, which is hopefully able to solve the issue of premature failure of rolling bearings in machines driven by frequency control technology.

变频调速技术作为我国电机系统节能改造的关键技术，已广泛用于工业生产、轨道交通和新能源汽车等领域。然而，由变频器诱导产生的MHz级高频轴电压对系统内轴承造成的“电蚀”损伤已成为困扰变频驱动系统运行安全的重要隐患。电蚀是指在轴电压下电流通过轴承并在轴承组件表面造成的电气损伤，已有关于摩擦界面电蚀机制的研究多采用直流或低频交流的电场条件，本项目拟采用更近于变频驱动系统轴电压特性的高频外加电场，系统研究高频电场下摩擦界面的电气损伤行为、液体润滑剂的击穿、降解和性能衰退行为等，阐明变频驱动系统中轴承电蚀的发生机制。进一步，从润滑材料角度出发，以强化摩擦界面耐电气损伤性能为切入点，结合抗电蚀纳米润滑添加剂，实现摩擦界面的润滑与电蚀防护功能一体化。本课题的开展有助于解决轴承电蚀这一影响变频驱动系统运行可靠性的共性问题，具有重要的经济和社会效益。