Effects of Passive Components on the Input Current Interharmonics of Adjustable-Speed Drives

Current and voltage source adjustable-speed drives (ASDs) exert the distortion current into the grid, which may produce some interharmonic components other than the characteristic harmonic components. This paper studies the effects of passive components on the input current interharmonics of ASDs with and/or without motor current imbalance. The investigation is done at different motor operating frequencies and load torque values. It shows that selecting the small filter components (ac choke, dc choke, and dc-link capacitor) results in different performances with respect to those interharmonics issued by motor current imbalance and other noncharacteristic interharmonics. The results are helpful for engineers investigating the effects of drive filters on the input current interharmonic components.