Three-phase PFC current control using dc-rail current as feedback

This paper presents a new current control method for three-phase power-factor-corrected (PFC) converters. The control method is a generalization to the nonlinear average current control previously developed for single-phase PFC converters, and uses only the DC-rail current as the feedback signal, avoiding the need to sense input phase currents and greatly simplifying current sensing requirements. Principle of the control method is presented first, followed by discussions of the implementation circuit and detailed design considerations. A mixed-signal implementation using an FPGA is also presented. Performance of the proposed control method is demonstrated by measurement results from a 2 kW prototype operating with both 60 Hz and high-frequency (400-800 Hz) lines.