Patent ID: 9130472
Filing Date: 2015-09-08
Classification: H02M,Y02B,Y02P

Abstract:
1. A single stage PFC fly-back or forward power supply comprising: a full bridge rectifier having output terminals (a positive terminal and a negative terminal), and input terminals which are coupled to AC power lines; a first capacitor coupled to the output terminals of the full bridge rectifier; an inductor; a first diode; a second diode; a forward transformer having three windings: a first winding, a second winding and a third winding; the second winding of the forward transformer and the first diode being connected in series, then being connected in parallel to the second diode; a second capacitor having a positive terminal and a negative terminal which is connected to a terminal of the third winding of the forward transformer; the inductor, the second diode and the second capacitor being coupled in series and then being coupled to the output terminals of the full bridge rectifier; the second diode connected in parallel to the series circuit including the second winding of the forward transformer and the first diode; the anodes of the first diode and the second diode coupled toward the positive terminal of the second capacitor, and the anodes of these two diodes coupled toward the positive output of the full bridge rectifier; or the cathodes of these two diodes coupled toward the negative terminal of the second capacitor, and the cathodes of these two diodes coupled toward the negative terminal of the full bridge rectifier; a switch having three terminals: a first terminal, a second terminal which is connected to the negative terminal of the second capacitor, and a control terminal which is coupled to the control circuit unit that generates a PWM or a PFM control signal; a main transformer comprising: a primary winding; a secondary winding for being coupled to the secondary circuit unit; the primary winding of the main transformer connected to the first winding of the forward transformer in series, then this series circuit being connected between the first terminal of the switch and the positive terminal of the second capacitor; the main transformer which is a forward transformer or a fly-back transformer; a third capacitor having a first terminal which is connected to the first terminal of the switch, and a second terminal; a third diode having an anode which is connected to the second terminal of the third capacitor, and a cathode which is connected to the positive terminal of the second capacitor; a fourth diode having an anode which is connected to the other terminal of the third winding of the forward transformer, and a cathode which is connected to the second terminal of the third capacitor.