| 摘要 |
Power factor correction (PFC) apparatus, controllers, and methods for operating bridgeless totem pole power factor correction converters in which AC input voltage polarity is detected for designation of active and freewheeling switches of the totem pole circuit, a nominal freewheeling switch on-time is determined according to a Volt×Second balance relationship, and the voltage across the designated active switch is sensed and used to selectively modify or offset the nominal freewheeling switch on-time to provide a computed freewheeling switch on-time for the next switching cycle to facilitate zero voltage switching of the active switch. |
