Comparison of Frequency and Time Domain Based Current Profiling Techniques for Acoustic Noise Reduction in Switched Reluctance Machine

Abstract

This paper comparatively analyzes the frequency and time domain based current profiling techniques for acoustic noise reduction in switched reluctance machines (SRMs) by utilizing finite element analysis. By breaking down a unipolar square wave current with the conduction angle of 120° electrical, the harmonic components of this baseline are reintroduced to create a current profile via the frequency domain. It is found that the turn-off slope of current profile, rather than the current harmonics, has the dominant influence on acoustic noise of SRMs. Hence, the current profile is then created in the time domain via a series of discrete points, allowing the turn-off slope to be controlled. Due to the slope at turn-off being a dominant feature in reducing acoustic noise and vibrations, the current profiling technique based on time domain is superior to that based on frequency domain.