US 12,289,055 B2
Flyback circuit and control method of clamping switch of flyback circuit
Qiangqiang Wang, Shanghai (CN); Daofei Xu, Shanghai (CN); and Jinfa Zhang, Shanghai (CN)
Assigned to Delta Electronics (Shanghai) Co., Ltd., Shanghai (CN)
Filed by Delta Electronics (Shanghai) Co., Ltd., Shanghai (CN)
Filed on Sep. 19, 2022, as Appl. No. 17/947,225.
Claims priority of application No. 202210391978.X (CN), filed on Apr. 14, 2022.
Prior Publication US 2023/0336086 A1, Oct. 19, 2023
Int. Cl. H02M 3/335 (2006.01)
CPC H02M 3/33569 (2013.01) 14 Claims
OG exemplary drawing
 
1. A control method of a clamping switch of a flyback circuit, wherein the flyback circuit comprises a transformer, a main switch, a clamping capacitor, a clamping switch, and a secondary rectifier unit, the transformer comprises a primary winding and a secondary winding, a turns ratio of the primary winding to the secondary winding is K, which is a positive number, the main switch and the primary winding are connected in series to receive an input voltage, the clamping switch and the clamping capacitor are connected in series and then connected to the primary winding in parallel, the secondary rectifier unit and the secondary winding are connected in series to provide an output voltage to a load, and the control method comprises:
when a product of K and the output voltage is greater than or equal to the input voltage, controlling the clamping switch to turn on M times during N consecutive switching cycles of the main switch, wherein 1=<M<N, and M and N are integers; and
when at least one of the output voltage and K changes, adjusting M/N correspondingly.