公开(公告)号：US20200336076A1

公开(公告)日：2020-10-22

申请号：US16959116

申请日：2018-12-29

Applicant: CSMC TECHNOLOGIES FAB2 CO., LTD. ,  SOUTHEAST UNIVERSITY

Inventor： Qinsong QIAN ,  Shengyou XU ,  Feng LIN ,  Hao WANG ,  Wei SU ,  Qi LIU ,  Longxing SHI

IPC: H02M3/335

Abstract: A control system for synchronous rectifying transistor of LLC converter, the system comprising a voltage sampling circuit, a high-pass filtering circuit, a PI compensation and effective value detection circuit, and a control system taking a microcontroller (MCU) as a core. When the LLC converter is operating at a high frequency, a drain-source voltage VDS(SR) of the synchronous rectifying transistor delivers, via the sampling circuit, a change signal of the drain-source voltage during turn-off into the high-pass filtering circuit and the PI compensation and effective value detection circuit to obtain an effective value amplification signal of a drain-source voltage oscillation signal caused by parasitic parameters, and the current value is compared with a previously collected value via a control circuit taking a microcontroller (MCU) as a core, so as to change a turning-on time of the synchronous rectifying transistor in the next period.

公开(公告)号：US20210194375A1

公开(公告)日：2021-06-24

申请号：US16617508

申请日：2018-09-28

Applicant: SOUTHEAST UNIVERSITY

Inventor： Qinsong QIAN ,  Shengyou XU ,  Qi LIU ,  Weifeng SUN ,  Shengli LU ,  Longxing SHI

IPC: H02M3/335 ,  H02M1/08

Abstract: The invention discloses a self-adaptive synchronous rectification control system and a self-adaptive synchronous rectification control method of an active clamp flyback converter. The control system comprises a sampling and signal processing circuit, a control circuit with a microcontroller as a core and a gate driver. According to the control method, a switching-on state, an early switching-off state, a late switching-off state and an exact switching-off state of a secondary synchronous rectifier of the active clamp flyback converter can be directly detected, and the synchronous rectifier and a switching-on time of the synchronous rectifier in next cycle can be controlled according to a detection result. After several cycles of self-adaptive control, the synchronous rectifier enters the exact switching-on state, thus avoiding oscillation of an output waveform of the active clamp flyback converter.