Flyback circuit and flyback converter

Abstract

The application provides a flyback circuit and a flyback converter. The flyback circuit comprises: a first circuit unit, including a first transformer, a first secondary rectifier diode and a first power switch tube; a second circuit unit, including a second transformer, a second secondary rectifier diode and a second power switch tube; a first capacitor, parallelly connected to the first circuitunit to form a first circuit module; a second capacitor parallelly connected to the second circuit unit to form a second circuit module. The first circuit module and the second circuit module are connected in parallel. Through the parallel capacitors, current balancing can be automatically provided for parallel modules; voltage stress is greatly reduced for switch tubes, and the problems are solved that, for instance, a flyback converter has high switch voltage stress and is inapplicable to medium and high powers; the power loss of the power switch tubes is dispersed, thermal stress is reducedfor power switch devices, system power density is increased, and the flyback converter is applicable to high-power uses.

Description

Technical field [0001] This application relates to the field of electronic technology, in particular to a flyback circuit and a flyback converter. Background technique [0002] In the related art, common flyback converters include single-tube flyback converters and interleaved parallel flyback converters. Such as figure 1 The single-tube flyback converter topology is shown, where Vi is the input voltage, T is the transformer, VT is the power switch, VD is the secondary rectifier diode, C is the output capacitor, RL is the output load, and Vo is the output voltage. The PWM drive signal is used to control the turn-on and turn-off of the VT, and the output voltage Vo can be adjusted by controlling the PWM signal. [0003] Single-tube flyback converters are widely used in small and medium power applications due to their simple structure, electrical isolation of input and output, wide voltage range and easy realization of multiple outputs. However, in a single-tube flyback converter, ...

AI Technical Summary

Problems solved by technology

However, the maximum voltage borne by the switching tubes of the interleaved parallel flyback converter is consistent with the maximum voltage borne by the switching tubes of the single-tube flyback converter, and the parallel structure will cause current inconsistencies due to the device differences of the two parallel modules, so that the external If a module with poor characteristics works under light load or even no-load operation, the consequence will inevitably be to make another module share more current stress, resulting in increased thermal stress, reduced lifespan, and reduced reliability of the entire system

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