Aplicação de sistema de aquecimento de rolamentos para redução de variabilidade de ensaios em motores de corrente contínua sem escovas

Abstract

This paper presents an experimental study on the impact of the temperature of bearings employed in a dynamometer bench for motor performance testing on the test results. To evaluate the relationship between the variables, an automatic test bench capable of measuring small variations of electric power was developed, adapted with a heating system for the motor bearings. The tests were performed with low-power brushless DC motors (electric power of about 10 W) and with grease lubricated metal ball bearings. The results showed that raising the operating temperature of the bearings to a point above that they would naturally reach during operation guarantees a fixed condition for the tests, thus reducing the variability of electrical power between tests from 0.82% to 0.04%. As a consequence, the use of the temperature control system for the bearings is capable of reducing the power variability within a test, as well as guaranteeing that tests performed in different time instants are under the same condition. Those characteristics enable the possibility of performing consecutive tests and improve the reproducibility of the test results.