大转动惯量负载用感应电机转子起动温升分析

大转动惯量负载用感应电动机是发电厂用于拖动风扇磨煤机旋转的专用感应电动机。由于风扇磨煤机的转动惯量大,使得拖动其旋转的电动机具有转动惯量大、起动电流大、起动时间长等特点,导致该种电动机起动过程的转子发热问题尤为突出。为了提高大转动惯量负载用感应电动机的起动可靠性,以一台国内最大容量的大转动惯量负载用感应电动机为研究对象,采用分点计算与曲线拟合的方法,建立了起动过程中转子铁耗、铜耗以及转子表面散热系数随转速变化的计算模型,利用有限元法对其起动过程中转子部件的损耗和温升进行了计算与分析。结果表明,该电动机的起动时间长达48s,在起动过程中转子铁耗、铜耗以及表面散热系数均随转速而变化,起动完成后转子最高温升达到141.1K。

Analysis on rotor starting temperature rise of induction motor with heavy rotary inertia load

The induction motor with heavy rotary inertia load is a specialized motor which drives the coal mill in the power station. Due to the heavy rotary inertia, the large starting current and long starting time resulting from the coal mill with heavy rotary inertia load, the loss and heat problems of the motor rotor in the starting process are more serious. To improve the starting reliability of the motor, an induction motor which is the largest capacity with heavy rotary inertia load in China is chosen as the research object. By the methods of discrete point calculation and curve fitting, the models of rotor core loss, rotor copper loss and rotor surface heat transfer coefficients with the change of rotor speed are established respectively at the starting process. And then, the rotor loss and the temperature rise at the starting process are calculated and analysed by the finite element method. The results show that the starting time of the motor is as long as 48 s. The rotor core loss, rotor copper loss and rotor surface heat transfer coefficients change with the rotor speed at the starting process. When the starting is completed, the highest rotor temperature rise is 141.1 K.