Inherent high power factor topologies

Since 1996, the European equipment manufacturers have had to comply with the IEC1000-3-2 standard. The mandatory compliance pushed many off-line switched mode power supply (SMPS) designers to use a boost power factor corrector (PFC) as preregulator stage. These existing boost PFC circuits exceed by far the standard requirements while providing additional benefits. Below 300 W of power capability, an alternative approach can comply with the standard by limiting the cost impact on the overall converter. This approach consists in transforming conventional SMPS topologies into "inherent high power factor" (IHPF) structures which still need a serial coil. These IHPF topologies easily comply with all classes of the standard while achieving power factor values above 0.95.