AC-DC Power-Factor Correction Supplies

This chapter begins with fundamental definition issues related to AC-DC power factor correction (PFC). It then examines the fundamental theory for boosting the PFC, the output capacitor size, and boost inductor selection. Boost PFCs' inductor may operate in two modes: discontinuous conduction mode (DCM) and continuous conduction mode (CCM). The chapter describes high-power PFC and load sharing. Most single-phase boost PFC power supplies available as commercial, off-the-shelf modules do not offer power more than 1 KW. To obtain high power, multiple modules are placed in parallel with active forward current control to assure load current sharing. The chapter also discusses startup considerations, output short-circuit protection, control issues, and three-phase PFC.