A Method to Determine PWM-Induced High-Frequency Harmonic Losses in a Converter-Fed Induction Motor by Experimental Tests

Abstract

The additional high-frequency losses present in converter-fed machines can constitute a significant portion of the overall motor system losses. Until now, no universally accepted method has existed to quantify and analyse these losses. This paper presents a universal method for determining the additional losses caused by pulse width modulation (PWM), which is validated using an induction motor. The proposed approach for segregating high-frequency harmonic losses assumes that these losses are equivalent to the total harmonic power observed at the motor terminals. The method requires no special arrangements or instrumentation; however, its accuracy naturally depends on the quality of the measurement instruments used. Moreover, this approach adds value to the evaluation of results obtained through the commonly used input–output method for efficiency determination. The ability to explicitly determine high-frequency harmonic losses in converter-fed machines opens new opportunities for innovation in motor control systems, modulation strategies and methods for minimising losses in such systems.