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

Abstract

Server power supply has to maintain output power even under abnormal input voltage conditions for stable operation of the server. Input-voltage-based current reference control has been widely used for power factor correction converter in server power supply because it can instantly generate a current reference and maintain a stable output. However, because harmonics and noise in the input voltage directly influence the current reference, the input current total harmonic distortion (THD) increases. On the other hand, phase-locked loop (PLL) based control can achieve lower current THD due to its excellent noise and harmonic filtering capabilities, but it cannot respond to sudden changes in the input voltage. In this letter, a hybrid current reference control method is proposed to achieve stable operation of the server power supply. The proposed method ensures continuous operation under abnormal input voltages by utilizing input-voltage-based control. Therefore, in normal input condition, the PLL bandwidth design can be alleviated to achieve a lower current THD. 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 Vrms 3-kW prototype converter.