Flyback power converter and secondary side controller circuit and control method thereof

• Main Authors: Chen, Chao-Chi, Li, Chuh-Ching, Chung, Hao-Wen, Lo, Li-Di, Chang, Wei-Hsu, Chen, Yu-Chang, Yang, Ta-Yung
• Format: Patent
• Language: English
• Published: 05.10.2021
• 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; BASIC ELECTRONIC CIRCUITRY; CODE CONVERSION IN GENERAL; CODING; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; DECODING; ELECTRICITY; GENERATION; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

A flyback power converter includes a primary side controller circuit for controlling a primary side switch; and a secondary side controller circuit for generating an SR (Synchronous Rectification) signal to control an SR switch. The SR signal includes an SR pulse and a ZVS (Zero Voltage Switching) pulse. The SR pulse controls the SR switch for synchronous rectification at the secondary side. The secondary side controller circuit samples and holds a voltage at a first end of the SR switch as a first voltage at a timing between the end of the ZVS pulse and the beginning of the SR pulse, and determines a length of the ZVS pulse so as to control the SR switch to be conductive for a ZVS time period, whereby the primary side switch achieves ZVS. The first voltage is proportional to an input voltage.