Test method for bearing electro-corrosion risk of variable frequency control alternating-current motor

Abstract

The invention discloses a test method for the bearing electro-corrosion risk of a variable frequency control alternating-current motor. The test method comprises the following steps; controlling an alternating-current motor by a variable frequency driver, and measuring a common-mode voltage V0 generated on a motor bearing; mounting a bearing oil film high-voltage insulation test tool on the end part of the motor, supplying different voltages to an inner ring and an outer ring of the bearing by using a constant-voltage power supply, and testing the maximum voltage V1 which can be borne by the bearing; comparing V1 with V0, and initially judging the electro-corrosion situation of the motor bearing; and further adding a motor bearing electro-corrosion durability test by using the bearing oilfilm high-voltage insulation test tool in order to assess whether the motor has a bearing electro-corrosion risk or not more accurately. Through adoption of the method, specific to the bearing electro-corrosion problem, unnecessary ceramic ball bearing and conductive ring structure are omitted, and the product cost is lowered. On the other hand, the risk of bearing corrosion quality problem of a product motor on the market is lowered, and after-sales loss is reduced.

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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