Tuned power inductors for hybrid active power filter with structure of hybrid magnetic core, distributed air gaps and three-phase five column

This paper proposes a new structure of tuned power inductors for hybrid active power filter (HAPF), featuring a hybrid magnetic core, distributed air gaps, and three-phase five-column structure. Detailed discussion of quality factor (Q), equivalent resistance (R/sub eq/), power losses, inductance linearity and mutual inductance are provided. Analysis and experiments show that: by using hybrid magnetic cores combining silicon steel and ferrite cores, inductors with low R/sub eq/, high Q value and desired mechanical strength can be achieved; distributed air gaps are an effective methods to improve linearity and to avoid the fringe effect around large gaps; the three-phase five-column structure leads to very small mutual inductance from phase to phase, and each phase inductance can be tuned independently which is required by HAPF. The findings in this paper are validated by industrial tests with a 50 kVA HAPFs.