Choosing appropriate test functions for noise analysis of electric motors
In many cases, additional noise analyses are required for determining the noise behavior of an electric motor. If the test is to be performed without using an external load, then the choice of the correct test function is crucial.
The test function should be selected so that all the forces that produce noise can be analyzed by respective sensors. The most common sources of noise are: rolling bearings, commutators and electric forces.
Based on the testing of DC motors in the automotive industry, it is shown that when a dynamic load is introduced under test conditions, assembly errors that lead to unacceptable noise for the customer can be identified and qualified. To a great extent, the detection of these errors depends on the selected test function. Quasi-periodic and pseudo-random test functions are examined and given guidelines for their use. In addition, it can be shown that a sound analysis by means of a suitable excitation function can be performed simultaneously with parameter estimation, thus, reducing the test time.