DC-link voltage effects on properties of a shunt active filter

The effect of the dc-link voltage on the compensation characteristics of a shunt active filter is studied focusing on 5^th negative and 7^th positive harmonic sequences. It is shown that the type of the harmonic load has a great impact on the required dc-link voltage. According to theoretical derivation there exist harmonic current sequence pairs yielding the minimum dc-link voltage requirement. Analytical equations concerning the 5^th negative and the 7^th positive harmonic sequences are proposed. Theoretical results are confirmed with measurements using a 19 kVA active front-end converter with active filtering capabilities.