Asymmetric Half-Bridge Flyback Control for Lower MOSFET Switching Loss
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Solution Overview
Problem
Existing power supply modules with asymmetric half-bridge flyback converter circuits face challenges in reducing the switching loss of the main power transistor, which affects power conversion efficiency.
Innovation Solution
A control circuit is introduced to manage the operation of the asymmetric half-bridge flyback converter circuit by controlling the rectifier circuit to discharge to the transformer within a preset duration before turning on the main power transistor, based on a comparison of the voltage difference between the drain and source of the main power transistor and a preset voltage value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the main power transistor is turned on immediately after the auxiliary power transistor is turned off, then the switching frequency is high and productivity is improved, but the voltage difference between drain and source is large causing high switching loss
Solution Approach 1:
The rectifier circuit is controlled to discharge to the transformer in advance during the dead time period before the main power transistor is turned on. This preliminary action reduces the voltage difference between drain and source of the main power transistor before switching occurs, thereby reducing switching loss while maintaining high switching frequency
Solution Approach 2:
The rectifier circuit acts as an intermediary element that discharges to the transformer during the dead time, mediating the voltage transition and reducing the voltage stress on the main power transistor before it turns on, thus lowering switching loss without affecting switching frequency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the switching loss of the main power transistor and improves the power conversion efficiency of the power supply module.
Implementation Method 1
the rectifier circuit to discharge to the transformer
Data Source
AI summary
This application provides a control circuit, a power supply module, and an electronic device. The power supply module includes a rectifier circuit and an asymmetric half-bridge flyback converter circuit which includes a main power transistor, an auxiliary power transistor, and a transformer. The control circuit controls the main power transistor and the auxiliary power transistor to be alternately turned on and off, so that the asymmetric half-bridge flyback converter circuit supplies power to a load. The control circuit is configured to: control the rectifier circuit to discharge to the transformer within preset duration; and after the rectifier circuit stops discharging to the transformer, control the main power transistor to be turned on based on a comparison result of a preset voltage value and voltage difference between a drain and a source of the main power transistor. This application reduce switching loss of the main power transistor.