KC-19-A029 -- The Impacts of Variable Frequency Drives on Drive System Efficiency

Variable frequency drives (VFDs) supply induction motors the pulse width modulation (PWM) power at variable frequency and voltage. In addition to the energy consumption by VFDs, the harmonics in the PWM power may generate additional motor power loss. An experiment was conducted on a VFD-motor drive system to investigate the VFD efficiency and additional motor power loss at the rated frequency. The experimental results show that the PWM power does not generate significant additional motor power loss and the VFD energy efficiency is 95.5% at the rated frequency for the studied drive system.