| Abstract |
The use of converters to feed motors instead of the direct-on-line supply has increased the need tounderstand the behaviour of the induction machine in different operating points. The additional lossesin frequency converter fed machines are caused by the harmonic content of a PWM voltage excitation.This paper investigates closely the harmonic contents of stator supply voltage and current. Most of theearlier studies have focused on sinusoidal supply or converter supply in only a few specific load pointswhile this study covers most of the frequency-torque plane below nominal values. A 15 kW standardsquirrel-cage machine's stator current and voltage time functions and spectra are analysed in 16 differentoperating points with torque values of 25 \%, 50 \%, 75 \% and 100 \% of the motor's rated torque andsupply frequency values of 25 \%, 50 \%, 75 \% and 100 \% of the motor's rated frequency. Measurementsin all 16 operating points are performed with both sinusoidal generator supply and with a frequencyconverter supply. |
