Improvement measures of cooling system for brushless exciter of high-speed synchronous motor

Author of the article:PU Bin, SHI Gengrui, YANG Fuchao, JIANG Sen

Author's Workplace：PipeChina West Pipeline Company, Urumchi, Xinjiang, 830013, China

Key Words：Exciter; Air duct; Temperature; Rotating rectifier plate

Abstract：The domestic high-power explosion-proof high-speed synchronous motor brushless exciter for long-distance pipeline systems caused multiple failures of the rectifier diodes due to the high operating temperature of the rotating rectifier plate. To solve this problem, it is necessary to analyze the reasons for the high operating temperature of the rotating rectifier plate and formulate improvement measures to reduce its operating temperature. Taking a 13 MW domestic synchronous motor exciter as an example, by analyzing the exciter structure, cooler efficiency and heating of the rotating rectifier plate, it is found that there are problems in the operation of the exciter where the cooling air volume of the rotating rectifier plate is small and the cooling air is not well circulated. Taking advantage of the structure in which the cooling air flows from the rotating rectifying plate to the top air duct has a large wind resistance, an improvement measure is proposed to use the top and bottom air ducts of this type of exciter at the same time to cool the heating parts on both sides of the exciter respectively. The cooling areas of the bottom air duct and the top air duct are independent of each other, the operating temperature of the rotating rectifier plate is rapidly reduced, hence the problem of small cooling air volume and poor cooling air circulation of the rotating rectifier plate of this model of exciter was verified. The field application shows that because the exciter generates less heat than the main motor, and the cooling air flow is small, the application of the improvement measures has no effect on the operating temperature of the synchronous motor. The research results can be of guiding significance for the cooling design of the domestic synchronous motor exciter in the future, and provide a reference for improving the reliability of the domestic synchronous motor.