真空干泵用屏蔽电机抗冲击持续带载能力评估与实验

Evaluation and experiment of impact resistance and continuous load capacity of canned motor for vacuum dry pump

针对真空泵在实际工作过程中,电机出现冲击载荷情况下持续带载能力无法合理利用的问题,对真空泵用屏蔽电机抗冲击持续带载能力进行了定量计算和实验分析。以一台5kW的屏蔽电机为例,根据真空泵实际工作运行时的冷却条件,利用有限元分析法对25℃和33℃两种冷却水温下电机额定运行时的稳态温度场进行计算,确定电机的最热点位置及最热点温度的安全裕量。通过设置过载转矩模拟冲击载荷,在不考虑电机动态特性的情况下,与电机最大转矩比较确定电机没有失速风险后,对电机过载状态下瞬态温度场进行计算得到电机在不同过载倍数下最热点的温升曲线,结合绝缘限制来定量计算电机在突加负载后的持续带载能力。通过对样机进行测试实验,将得到的测试结果和仿真结果进行对比分析表明,电机在额定运行时带载能力有待进一步发掘,在合理负载率的冲击载荷下仍可以在其允许的时间内安全连续运行。该研究对电机实际运行时过载能力的充分应用以及冲击载荷过大时电机保护装置操作时间的更精确确定提供了科学依据。

Aiming at the problem that the continuous load carrying capacity of the motor under impact load cannot be reasonably utilized in the actual working process of the vacuum pump,the continuous load capacity of canned motor for vacuum pump is calculated quantitatively and analyzed experimentally.Taking a 5 kW canned motor as an example,according to the cooling conditions of the vacuum pump in operation,the finite element analysis method was used to calculate the steady state temperature field of the motor in rated operation under 25℃ and 33℃ cooling water,so as to determine the hot spot position and the safety margin of the hot spot temperature.By setting the overload torque to simulate the impact load,and without considering the dynamic characteristics of the motor confirming that the motor has no risk of stalling,the transient temperature field under the motor overload state was calculated to obtain the temperature rise curve of the hottest point of the motor under different load multiples,and the insulation limit was used to quantitatively calculate the motor continuous load capacity after sudden load.By carrying out load capacity test experiments on the prototype,a comparative analysis of the obtained test results and simulation calculation results shows that the motors rated operating load capacity needs to be further explored,and the motor can still operate safely and continuously within the allowable time under the impact load with reasonable load rate.This research has a certain reference basis for the full application of overload capacity and the determination of the operating time of motor protection device when the impact load is too large.