Harmonic Torque and Speed Pulsations in a Rectifier-Inverter Induction Motor Drive

A method of predicting the 6th-harmonic electromagnetic torque of an induction motor arising from a rectifier-inverter power source is presented. This study includes both the effects of harmonic variation rotor speed and inverter voltage. Although only the 6th harmonic is considered, it is shown that this is sufficiently accurate to predict steady-state system performance for practical speed ranges and system parameters. This investigation reveals that the 6th-harmonic electromagnetic torque pulsation may, at low frequencies, be significantly greater than that predicted by a constant speed, constant voltage analysis heretofore employed, and may materially affect the performance of the system.