Torque ripple in PWM-VSI-fed drives due to parasitic effects in the inverter control

Smooth torque production is one of the most important quality criteria for PWM-VSI-fed drives operation. In an ideal case merely additional torque harmonics of the switching frequency and of its multiples occur compared to sinusoidal power supply operation of a drive. At switching frequencies in kHz-range they are absorbed by the inertia of the machine and do not deteriorate the drive performance. Although additional low order torque harmonics may occur due to parasitic effects during the PWM operation. Low order torque harmonics are particularly undesired, because they may cross the mechanical resonance frequency of a drive train. New low order torque harmonic sources are described in the paper and compensation methods are proposed for them.