Dynamic-Loss-Free Stability Enhancement for DC Data Center Power Systems With Impedance-Reshaped Flying Capacitor

Chip load power quality and bus voltage stability are critical in DC data center power systems (DC DCPS). However, with the growing integration of green energy and increasing power consumption in DCPS, voltage oscillations are easily triggered. These oscillations are primarily caused by the impedance mismatch between cables and the constant power loads (CPLs) in DCPSs. Traditional virtual impedance methods are widely used to suppress such oscillation, but at the expense of sacrificing load converter's dynamic performance. To overcome this limitation, an impedance-reshaped flying capacitor (IRFC) approach based on the flying-capacitor three-level (FC-TL) Buck converter is proposed in this paper. By utilizing the decoupling control structure and regulating the flying capacitor transient voltage, IRFC can achieve oscillation suppression effectively without compromising the converter's output performance. The proposed method is experimentally validated on a 48 V, 500 W platform, demonstrating its effectiveness and practical advantages.