Power Quality Conditioning Using Bridged-T Filters for Passive Rectifiers

Harmonic standards such as IEEE 519 have prompted the adoption of active rectifiers or the use of multiple pulse rectifiers for three phase AC-DC conversion system in variable speed drives and other applications. Although active rectifiers are capable of excellent line current waveforms and DC bus regulation, they do result in increased EMI at the input terminals. On the other hand, passive filters typically require a modest amount of reactive elements if configured appropriately. This paper presents the application of a passive filter for input current filtering for passive rectifiers. Filter design equations and operation during voltage imbalances are discussed. Computer simulation and experimental results are presented that verify the operation of the filter.