Off-line flyback converter with input harmonic current correction

An offline flyback power converter employing coupled primary transformer windings to achieve input harmonic current correction is introduced. By controlling the turn-ratio of the windings, the input current harmonic contents can be reduced to comply with EN611000-3-2 limits while boosting only slightly the bulk capacitor voltage. Such a topology allows the use of commercially available electrolytic capacitors for energy storage and introduces minimum cost penalty. The basic operation of the power converter is discussed and hardware results from a prototype circuit presented