Integrating Voltage-Source Active Filters into Diode Front-End Rectifiers – Harmonic Mitigation and Power Factor Correction

The ongoing grid integration of power electronic based loads requires the increasing use of power filters in order to maintain a high power quality and stability. To address this challenge, conventional active and passive filters are commonly used to meet the harmonic limits defined by the grid code. They allow the mitigation of voltage and current harmonics, however the filter performance is often subject to a limited frequency range or a frequency dependent harmonic mitigation. This paper presents a novel control scheme with a significantly reduced frequency dependence of harmonic mitigation for a voltage-source active filter configuration. Although high control bandwidth and identification of individual harmonics are not required, the harmonics of a diode front-end rectifier can almost entirely be eliminated, while the active filter load is consistently limited to harmonic currents in steady state and transient operation. As a result, the parallel voltage-source active filter can be designed for a small share of the installed load power and constitutes a promising alternative to conventional power filters.