No abstract

The parallel operation of modular power factor correction circuits is illustrated. The modular units using boost converters are operated at a constant frequency with variable dutyratio. Flexible load demand is met by changing the number of operating modules under the maximum current limit. The operating modules have the same frequency and duty-ratio, but are equally phase-shifted to each other by a fraction of the switching period to reduce the ripple content and to increase the ripple frequency of the input current. With this phase-shifted control strategy, balanced current sharing among modules can be achieved by operating the boost converters at discontinuous current mode, without the need of extra current control circuit. A prototype circuit consisting of 15 modular units, which supply the attempted power rating of 3.75 kVA was implemented to verified the theoretical prediction.