Current-sharing among parallel-connected systems of active power factor correction

This paper presents active current-sharing control approaches for parallel-connected AC-to-DC power system architectures consisting of multiple power-processing channels, each of which comprises a cascade connection of a front-end active power factor correction (APFC) stage and an isolated back-end DC-DC converter. By employing a current-sharing method to the back-end converters, current-mode commercial-off-the-shelf (COTS) DC-DC converters can provide uniform current-sharing among all power-processing channels while retaining stiff system output voltage regulation without control conflicts among output voltage regulators distributed in the converters. This results in uniform power-sharing among the front-end APFC stages that are connected to either a common AC power source or independent AC power sources that may possess different frequencies of operation (i.e. 50 Hz versus 60 Hz). Through computer simulation and an experimental prototype, current-sharing control for the parallel-connected APFC architectures is validated and successfully applied.