A test method for the risk of electrical corrosion of bearings in AC motors controlled by frequency conversion

Abstract

The invention discloses a test method for bearing electrical corrosion risk of an AC motor controlled by frequency conversion, comprising: using a frequency conversion driver to control the AC motor, measuring the common-mode voltage V0 generated on the motor bearing; installing bearing oil film withstand voltage test tooling at the end of the motor , use a constant voltage power supply to provide different voltages to the inner and outer rings of the bearing, and test the maximum voltage V1 that the bearing can withstand; compare the size of V1 and V0, and initially determine the electrical corrosion of the motor bearing; use the bearing oil film pressure test tool, and further Increase the electrical corrosion durability test of motor bearings to more accurately evaluate whether the motor has the risk of electrical corrosion of bearings. The invention aims at bearing electric corrosion problem, on the one hand, it reduces unnecessary ceramic ball bearings and conductive ring structures, and reduces product cost; on the other hand, it reduces the risk of bearing corrosion quality problems in product motors in the market, and reduces after-sales losses.

Description

technical field [0001] The invention relates to the field of bearings of AC motors, in particular to a method for testing the electric corrosion risk of bearings of AC motors controlled by frequency conversion. Background technique [0002] The current mainstream electric drive systems on the market use pulse width modulation (PWM) to control the motor speed, which means that a common-mode voltage will be generated on the motor bearings through capacitive induction. When these voltages accumulate to a level greater than the breakdown voltage of the bearing grease, they arc in the motor bearings and discharge along the path of least resistance between the motor bearings, causing electrical corrosion of the bearings with spotting and loss of grooves, which in turn can lead to serious damage to the bearings. Damage, abnormal noise of the motor. [0003] Section 31.4.4.3 of the authoritative standard for industrial motors, NEMA MG1, states that a capacitive shaft voltage of 10 ...

AI Technical Summary

Problems solved by technology

[0004] However, in the field of new energy electric drives, the method for evaluating the possibility of electric corrosion in motors is missing.

During the design and trial production process of a new motor, it is impossible to evaluate whether the motor has the risk of bearing current corrosion

However, since the front end of the new energy motor cooperates with the gearbox and is used in automobiles, it cannot refer to the carbon brush solution of industrial motors that are easy to wear and need to be replaced regularly.

Therefore, in the design of most new energy drive motors on the market, the problem of shaft current failure is not considered, and more rectifications are made after the feedback of shaft current corrosion problems in the market

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