基于直流注入的三相感应电动机等效负载热试验研究

Research on Equivalent Load Thermal Test of Three-Phase Induction Motor Based on DC Injection

基于直流注入的等效负载试验是确定三相感应电动机温升的一种间接方法,具有无需在电机轴端耦合机械负载、能耗低等优势。根据这一原理设计了一套具有交、直流供电回路的24工位热试验装置。装置在供给电机交流电的同时,注入连续且电流可调的直流电流,增加在电机绕组上的电流有效值,实现等效负载,从而完成电机的热试验。试验表明:直流注入等效负载法标准偏差稍大于直接负载法试验标准偏差,不确定度在可接受范围内。该装置可用于电机加速热老化试验,分析其绝缘性能,获得电机的预期寿命。

An equivalent load test based on DC injection is designed to allow the temperature rise of the induction motor at rated load to be determined experimentally from a single test at conditions other than rated load.This method is often used in the cases of special machines with inaccessible free shaft ends,high-speed machines or vertical machines.According to this principle,a set of 24-position thermal test device with AC and DC power supply circuit is designed.The device injects continuous and adjustable DC current while supplying AC power to the motor,increases the effective value of current in the motor winding,realizes equivalent load,and completes the thermal test of the motor.The test shows that the standard deviation of the DC injection equivalent load method is slightly larger than that of the direct load method,and the uncertainty is within an acceptable range.This device can be used in the accelerated thermal aging test of the motor to analyze its insulation performance and obtain the expected life of the motor.