This paper is focused on the load torque evaluation of the induction machine. There is described the problem of load torque oscillations and its impact to other electromagnetic variables in induction machine. In this article, the issue of modulated stator current is resolved and behaviors of amplitude and phase modulation are separated using demodulation algorithms after that. Newly, the variable load torque is retroactively determined from coefficients of amplitude and phase modulation not from nondemodulated stator current frequency spectrum. At last, theoretically acquired knowledge is compared with real measurement and different values of amplitude and phase modulation obtained from the mathematical motor model and from the real measurement are discussed. In the future, this analysis can be used as a basis for online diagnosis of driven load.
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