A method for analyzing the safety of the shaft system when the motor is running at variable frequency

Abstract

The invention relates to a safety analysis method of an axis system during variable frequency operation of a motor. The method comprises steps of 1), testing dynamic torque signals on a rotation shaft near a diaphragm coupling during variable frequency operation of the motor, and acting the dynamic torque signals to a diaphragm of the diaphragm coupling and the rotation shaft so as to obtain torsional stress borne by the rotation shaft and dynamic tension and compression stress borne by the diaphragm; and 2), according to working features of the rotation shaft and the diaphragm coupling, using a nominal stress method to calculate fatigue life of the rotation shaft under the effect of high cycle load, and using a local stress method to calculate the fatigue life of the diaphragm under the low cycle load, and using a quite small value of the two kinds of calculated life to estimate the fatigue life of the axis system. Compared with the prior art, the safety analysis method is advantageous in that the safety analysis method is simple and feasible, and effects of steady-state and dynamic torque on the rotation shaft of a variable frequency driving motor are considered.

Description

technical field [0001] The invention relates to the evaluation of the safety state of the shaft system of large-scale rotating machines such as power, metallurgy and petrochemical industry, and in particular to a method for analyzing the safety of the shaft system when the motor is operated with frequency conversion. Background technique [0002] In order to save energy and reduce emissions, high-power power equipment such as fans and pumps in industries such as electric power, petrochemical, and metallurgy are undergoing or plan to implement frequency conversion transformation, through variable speed operation to meet the adjustment needs of different load conditions, thereby reducing throttling losses and improving energy conversion. efficiency. [0003] For fans and pumps that operate at a traditional constant speed, the strength of the shaft system can mostly meet the design requirements, and shaft damage accidents rarely occur within the service life. After the frequen...

AI Technical Summary

Problems solved by technology

However, torsional resonance or self-excited instability may occur when the shafting system driven by the variable frequency drive runs within a certain speed range. Exceeding the amplitude of the torque transmitted by the motor itself, the above calculation and analysis method fails

Because key parameters such as the frequency and amplitude of the pulsating torque on the shaft are difficult to give accurately, it is difficult to accurately evaluate the fatigue life of the shafting under the action of torque pulsation

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