Design and Control Strategy of PFC During AC Dropout in a High Reliability and High-Power Density Server Power Supply

A control algorithm is proposed such that when AC comes back from dropout event, both the re-rush input current (when instantaneous input voltage V
IN
is larger than the power factor correction circuit output voltage V
BULK
) and non-re-rush input current (when V
IN
< V
BULK
) are well controlled such that they are high enough to rapidly boost V
BULK
but low enough to meet the recently released server modular hardware system – common redundant power supply (m-CRPS) specification. This, along with a compact baby boost converter (added between power factor correction circuit and isolated DC/DC converter stage), provide a strategy for AC drop operation for a high-power density power supply.