Technical Articles

Harmonic Mitigation in Variable Frequency Drives: 6-Pulse Drive with Matrix AP Harmonic Filter vs. AFE Drive

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Todd Shudarek, Principal Engineer – The proliferation of variable frequency drives (VFDs) has brought increased attention to harmonic effects created by drives. A standard 6-pulse drive with no harmonic mitigation technology may interfere with neighboring equipment, reduce equipment life, and negatively impact the utility power quality. Under some circumstances the total harmonic current distortion (THID) may approach the level of the fundamental current. Some drive manufacturers recommend Active Front End (AFE) drives to combat these effects. An alternative solution is the use of a traditional 6-pulse drive equipped with a passive harmonic filter; however, typical passive harmonic filters experience reduced effectiveness at loads less than 100%. With the introduction of adaptive passive technology, the Matrix AP harmonic filter maintains strong harmonic filtering performance across a wide range of loads. This paper compares the performance of a 20 HP AFE drive with the performance of a standard 30 HP 6-pulse drive equipped with a 44 amp Matrix AP harmonic filter.