What are the harmonic levels?

VFD manufacturers often set the carrier frequency at 3 kHz or less. Higher carrier frequency frequencies result in higher switching losses and can contribute to problems with ringing voltages stressing the motor insulation. There should be no problem with harmonic distortion of the motor current waveform at 1.5 to 3 kHz. There could be problems with acoustical noise generation in the motor if the motor is installed in a quiet area. VFD manufacturers offer a switching frequency increase adjustment to 15 kHz or so to reduce acoustical noise at the cost of reduced efficiency and perhaps de-rated output current rating.