Causes and Effect of Inverter Harmonics

This chapter provides a causes and effects of inverter harmonics on ac drive system. It begins with an introduction to harmonics - unwanted higher frequencies superimposed on the fundamental power frequency that distorts voltage and current waveforms. The generation of different harmonic orders and sequences is explained along with graphical representations.

The effects of harmonics, which includes deviations in torque-speed curves, increased skin effect and associated losses, cogging and crawling effects, noise and vibration issues, and impacts on efficiency and temperature rise has been provided considering induction motor as a load.

The harmonic interaction produces problematic effects like torque pulsations, speed oscillations, mechanical vibrations and noise. Additional iron and copper losses due to the higher frequencies also lower efficiency and lead to excessive heating. Mitigation methods like proper design of the number of stator and rotor slots has been suggested. Overall, the analysis provides important insights into analyzing, quantifying, and minimizing the impacts of supply harmonics feeding induction motors.