US 12,113,448 B2
Zero-voltage-switching flyback converter with reduced secondary side current and voltage stress
Huaming Guo, Campbell, CA (US); Yi Xu, Campbell, CA (US); Zhaowu Luo, Campbell, CA (US); Yongcai Lai, Campbell, CA (US); and Jianming Yao, Campbell, CA (US)
Assigned to DIALOG SEMICONDUCTOR (UK) LIMITED, London (GB)
Filed by DIALOG SEMICONDUCTOR (UK) LIMITED, London (GB)
Filed on Jul. 28, 2021, as Appl. No. 17/443,890.
Claims priority of provisional application 63/057,859, filed on Jul. 28, 2020.
Prior Publication US 2022/0038020 A1, Feb. 3, 2022
Int. Cl. H02M 3/335 (2006.01); H02M 1/00 (2006.01)
CPC H02M 3/33592 (2013.01) [H02M 1/0058 (2021.05)] 20 Claims
OG exemplary drawing
 
1. A zero-voltage switching (ZVS) flyback converter, comprising:
a transformer having a primary winding, a secondary winding, a first auxiliary winding, and a second auxiliary winding;
an SR switch transistor in series with the secondary winding;
a first diode;
an auxiliary capacitor in series with the first auxiliary winding and the first diode, wherein the first diode is configured to allow a charging current to flow from a positive terminal of the first auxiliary winding into a positive terminal of the auxiliary capacitor and to prevent a current flow into the positive terminal of the first auxiliary winding;
a second diode; and
a ZVS switch transistor in series with the second auxiliary winding and the second diode, wherein the second diode is configured to allow a discharging current to flow from the positive terminal of the auxiliary capacitor through the second auxiliary winding while the ZVS switch transistor is on and to prevent a current flow through the second auxiliary winding while the charging current is conducting.