A Hybrid Current Reference Control Method for PFC Converter in Server Power Supply

The input voltage-based current reference control of the power factor correction (PFC) converter has been used for server power supplies because it can operate immediately even at abnormal line voltage. However, when the input voltage-based control method is digitally implemented, the total harmonic distortion (THD) of the input current increases due to sensing errors and noise. On the other hand, the phase-locked loop (PLL)-based current reference control can reduce the effect of sensing noise and achieve low current THD by using the calculated phase, but it cannot be operated immediately at abnormal line input. This paper proposes a hybrid current reference control method which uses both input voltage-based and PLL-based control to achieve stable operation of the server power supply. The proposed method achieves low current THD through PLL-based control during steady-state operation, and it can respond immediately through input voltage-based control when abnormal input occurs. To determine the effectiveness of the proposed control method, steady-state operation and abnormal input condition operation were confirmed through a 47-64 Hz/90-264 V
rms
3 kW prototype converter.