Patent ID: 9748854
Date: 2017-08-29
CPC Classifications: H02M,Y02B,Y02P

Claim:
1. An alternating current (AC)-direct current (DC) conversion circuit, comprising: an input rectifier circuit, a primary side input filtering capacitor, a primary side inverter circuit, a drive circuit, an isolation transformer, a secondary side rectifier circuit, a third and a fourth secondary side capacitors, a secondary side output filtering capacitor, and a control circuit connected between the secondary side output filtering capacitor and the drive circuit, wherein the drive circuit is connected to the primary side inverter circuit; wherein the input rectifier circuit comprises a first and a second input rectifier diodes; an anode of the first input rectifier diode and a cathode of the second input rectifier diode are connected to an AC input live line; the primary side input filtering capacitor comprises two high-frequency input filtering capacitors that are connected in series by using an AC input neutral wire as a middle point; opposite ends of each of the two high-frequency input filtering capacitors are separately connected to a positive end and a negative end of the input rectifier circuit; wherein the primary side inverter circuit comprises a first and a second inverter switching transistors; the first inverter switching transistor and the second inverter switching transistor are separately connected to the positive end and the negative end of the input rectifier circuit; one end of a primary side winding of the isolation transformer is connected to the first and the second inverter switching transistors in series; the other end of the primary side winding of the isolation transformer is connected to the input neutral wire; the primary side inverter circuit and the primary side input filtering capacitor also form a loop, so as to form a clamping resonant circuit; the inverter switching transistors work at a zero voltage switching (ZVS) state; wherein the secondary side rectifier circuit comprises a third and a fourth diodes; a cathode of the third diode is connected to an anode of the fourth diode and an output end of the secondary side winding of the isolation transformer; a cathode of the fourth diode is connected to a positive output end of a power supply and one end of the secondary side output filtering capacitor; an anode of the third diode is connected to a negative output end of the power supply and the other end of the secondary side output filtering capacitor; the other output end of the secondary side winding of the isolation transformer is connected to the middle point of the third and the fourth secondary side capacitors; the third secondary side capacitor is connected to the positive output end of the power supply; the fourth secondary side capacitor is connected to the negative output end of the power supply; and the secondary side rectifier circuit has two operation modes comprising a forward operation mode and a flyback operation mode.