A new model for calculating additional induction motor losses due to harmonics associated with PWM voltage-source inverters is presented. A simple and low-cost measurement using a small inverter to calculate the coefficients to be used in this loss model is presented for any size induction motor. Based on measurements of motor losses from 300 Hz to 10 kHz, the new model assumes much higher losses at higher voltage harmonics than the conventional models. It is shown that sine-wave modulation (at - 3.6 kHz modulation frequency) results in higher losses than the six-step operation, while there is a loss minimum at overmodulation. The new model will be useful for the evaluation of various modulation schemes for high-frequency transistor inverters.
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