大功率防爆高速同步电机无刷励磁机冷却系统改进

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

长输管道国产大功率防爆高速同步电机(以下简称国产同步电机)的无刷励磁机(以下简称励磁机)因旋转整流盘运行温度高导致整流二极管多次失效。为解决该问题,需要分析旋转整流盘运行温度高的原因,并制定改进措施以降低运行温度。以某13 MW国产同步电机励磁机为例,从励磁机结构、冷却器效率、旋转整流盘发热等方面分析,发现励磁机运行中存在旋转整流盘冷却空气流量小、冷却空气流通不畅的问题。利用其冷却空气由旋转整流盘流向顶部风道存在较大风阻的结构,提出同时使用励磁机顶部与底部两组风道的改进措施,分别对励磁机两侧的发热部位进行冷却,底部风道与顶部风道冷却区域相互独立,大幅度降低了旋转整流盘的运行温度,也验证了该型号励磁机旋转整流盘冷却空气流量小、风道不畅的问题。现场应用表明,由于励磁机较主电机发热量小、冷却空气流量小,应用改进措施后对国产同步电机运行温度无影响。研究成果对今后国产同步电机励磁机的冷却系统设计有参考意义,为提升国产同步电机可靠性提供借鉴。

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.