Why does the line current look distorted at no load?

The absolute value of the current harmonics generated by the drive is independent
of the load current, meaning that the absolute value of the harmonics is nearly the
same at no load as at nominal load. That is why the current waveform looks
distorted even when the load current is very low. This is not an issue as the harmful
effects of harmonics depend on the absolute harmonic content based on nominal
load. For example, the standards like IEEE519-1992 refer to harmonic content as a
percentage of the total load current.
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