FLYBACK POWER SUPPLY CIRCUIT AND ZVS CONTROL CIRCUIT AND CONTROL METHOD THEREOF

• Main Authors: LIN ZICHENG, LIN KUNYU, LUO LIDI, ZHANG WEIXU
• Format: Patent
• Language: Chinese; English
• Published: 08.10.2021
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION

The invention provides a flyback power supply circuit and a ZVS control circuit and control method thereof. The ZVS control circuit for controlling a flyback power supply circuit includes: a primary side controller circuit for generating a switching signal, to control a primary side switch; and a secondary side controller circuit for generating a synchronous rectifier (SR) control signal for controlling a synchronous rectifier switch. The SR control signal includes an SR-control pulse and a ZVS pulse. The SR-control pulse controls the synchronous rectifier switch to perform secondary side synchronous rectification. The secondary side controller circuit determines a trigger timing point of the ZVS pulse according to a waveform characteristic of a ringing signal, to control the synchronous rectifier switch to be ON for a ZVS period, thereby achieving zero voltage switching of the primary side switch. The ringing signal is generated by resonance oscillation of the power transformer after demagnetization in a non