Учет влияния колебаний температуры обмотки статора на термический ресурс асинхронного двигателя

Abstract

The work is aimed at solving the problem of reducing the accident rate of induction motors, increase the service life and efficiency of their use by improving the accuracy of the estimation of the thermal state at the design stage and during the exploitation. The paper discusses the problem of determining the limits of applicability of the average loss method for estimating the thermal state of asynchronous motors in intermittent mode and refinement of this method, taking into account the nonlinear coupling between rate of aging of insulation and temperature, as well as the ratio of the cycle parameters and the thermal time constant of the motor. We used analytical methods and computer experiment, based on the five-mass thermodynamic model of the induction motor. It is found that there exist such combinations of parameters of cycle in intermittent mode for which evaluation of the thermal state of the induction motor by the average loss method is incorrect. We propose a refined method of estimating the thermal state of the induction motor by the traditional average loss method by introducing a correction coefficient that takes into account the nonlinear coupling of the rate of aging of insulation from the stator winding temperature, we obtain formulas for the calculation of this coefficient. It is shown that within the formal borders of intermittent mode (cycle time no more than 10 min), divergence between the results obtained analytically and via five masses thermodynamic model of the induction motor used in the computational experiment is quite small and does not exceed 6...8%.