Parallel operation of modular power factor correction circuits

摘要

The parallel operation of modular power factor correction circuitsnis illustrated. The modular units using boost converters are operated atna constant frequency with variable duty-ratio. Flexible load demand isnmet by changing the number of operating modules under the maximumncurrent limit. The operating modules have the same frequency andnduty-ratio, but are equally phase-shifted to each other by a fraction ofnthe switching period to reduce the ripple content and to increase thenripple frequency of the input current. With this phase-shifted controlnstrategy, balanced current sharing among modules can be achieved bynoperating the boost converters at discontinuous current mode, withoutnthe need of extra current control circuit. A prototype circuitnconsisting of 15 modular units, which supply the attempted power ratingnof 3.75 kVA was implemented to verified the theoretical prediction