US 2024/0204674 A1 · FLYBACK CONVERTER WITH HIGH EFFICIENCY AND CONTROL METHOD THEREOF

Abstract

Disclosed is a high-efficiency flyback converter and a control method thereof. The flyback converter comprises: a transformer; a first switch transistor and a second switch transistor; a resonant capacitor; a control circuit, for controlling the second switch transistor to be turned on for a first time before the first switch transistor is turned on during a switching cycle, controlling the second switch transistor to maintain turn-off state during a first time stage, to control energy transmission between primary and secondary sides to include two time stages during a switching cycle, the first time stage lasts for a set time period during a freewheeling process. The present disclosure allows the main switch transistor to realize zero-voltage turn-on, thus reducing conduction loss of the primary and the secondary sides, reducing ripples of an output voltage and a current of the secondary side, and being beneficial to improving operating efficiency.

Claims17

Dependent claims

A flyback converter with high efficiency, comprising:

a transformer;
a first switch transistor and a second switch transistor, which are connected in series between a voltage input terminal and reference ground;
a resonant capacitor, wherein a resonant loop of the flyback converter is formed based on the resonant capacitor and a leakage inductor of the transformer when the second switch transistor is in turn-on state;
a control circuit, configured to generate control signals for the first switch transistor and the second switch transistor,
wherein the control circuit is configured to:
in a switching cycle, control the second switch transistor to be turned on for a first time before the first switch transistor is turned on, and control the second switch transistor to maintain turn-off state during a first time stage of the flyback converter, so as to control energy transmission between a primary side portion and a secondary side portion of the flyback converter to include two time stages in a switching cycle,
wherein, the first time stage lasts for a set time period during a freewheeling process of the flyback converter.

4 more elements

A control method of a flyback converter with high efficiency, wherein the flyback converter comprises a transformer, a first switch transistor, a second switch transistor, and a resonant capacitor, and the control method comprises performing following steps in each switching cycle:

controlling the second switch transistor to be turned on for a first time before the first switch transistor is turned on, so as to control a leakage inductor of the transformer to resonate with the resonant capacitor and transfer energy on the resonant capacitor to a secondary side portion of the flyback converter;
controlling the first switch transistor to be turned on after the second switch transistor is turned off, so as to charge an excitation inductor of the transformer and the resonant capacitor;
controlling the first switch transistor to be turned off to control the excitation inductor of the transformer to be the demagnetized, so as to transfer energy on the excitation inductor to the secondary side portion of the flyback converter.

Dependencies are inferred from the claim text.

Flyback converter with high efficiency and control method thereof

Life of this patent

Flyback converter with high efficiency and control method thereof

Life of this patent

Abstract

Claims17