Patent ID: 6954367
Filing Date: 2005-10-11
Classification: H02M,Y02B

Abstract:
1. A pulse width modulated soft-switching power converter, comprising a transformer, a secondary circuit, a first diode, a second diode, an inductor, a capacitor, a pair of main switches, a pair of auxiliary switches, and a controller, characterized in that said controller generates a first switching signal and a second switching signal to operate said pulse with modulated soft-switching power converter in four operation stages, wherein: power is delivered from said primary winding to said secondary winding in a first operation stage for each switching cycle, wherein said main switches being switched on and said auxiliary switches being switched off in said first operation stage; energy stored in said transformer is reset and freewheeled back to said input voltage source through said auxiliary switches, and energy stored in said secondary circuit is continuously output in a second operation stage for each switching cycle, wherein said main switches being switched off and said auxiliary switches remaining off in said second operation stage, and a time period of said second operation stage being variable according to an energy stored in said transformer; said transformer operates as an inductor with said secondary winding open circuited, so as to realize a zero-current switching mode of said auxiliary switches in a third operation stage for each switch cycle, wherein said main switches remaining off and said auxiliary switches being switched on in said third operation stage; and energy stored in and magnetizing said transformer in said third operation stage flies back to said input voltage source through said main switches to achieve a zero-voltage transition in a four operation stage for each switching cycle, wherein said main switches remaining off and said auxiliary switches being switched off in said fourth operation stage.