On the Effects of Ultra-High Switching Frequency on PWM-Inverter-Fed Induction Motors

When the ‘ultra-high switching frequency’ concept is evoked, the mind immediately runs towards the wide bandgap semiconductors and to inverters having unimaginable gravimetric and volumetric power densities. More rarely, people are interested in the effects of very high frequency pulse width modulation on the electrical load, particularly when considering ‘rugged’ induction machines. Starting from this observation and being aware that these inverters are dedicated only to ‘special’ machines and applications, the authors decide to investigate what happens - in a broad sense - to induction motors supplied by inverters with switching frequencies up to 350 kHz. After an introduction on wide-bandgap semiconductor device technologies, the paper presents some interesting experimental observations conducted on a 1.1 kW 4-pole induction motor fed by a silicon carbide inverter.