Phase-Shifted Full-Bridge Control for Soft Turn-Off Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional DC-DC converters with phase-shifted full-bridge circuits suffer from high loss and poor anti-interference ability due to hard switching of transistors on the lagging leg, leading to electromagnetic compatibility (EMC) issues.
Innovation Solution
A method and device for controlling switching transistors in a DC-DC converter that ensures soft-switching turn-off by determining if the current through the transformer is less than or equal to a preset value before turning off the corresponding switching transistor on the lagging leg.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the switching transistor on the lagging leg is controlled to be turned off in conventional phase-shifted full-bridge circuit, then the switching transistor can be turned off timely, but the current flowing through the switching transistor is still very large causing large loss and hard switching state
Solution Approach 1:
The patent applies preliminary action by detecting the transformer current before turning off the switching transistor on the lagging leg. The control method checks whether the current is less than or equal to a preset value before initiating the turn-off command, ensuring that the transistor is turned off only when the current has naturally decreased to a safe level. This preliminary current detection prevents hard switching by preparing the turn-off condition in advance based on current state, thereby reducing switching losses while maintaining timely switching control.
2Device complexity
If the switching transistor on the lagging leg works in hard switching state, then the switching control is simple, but the anti-interference ability is low and EMC noises are generated
Solution Approach 1:
The patent implements feedback by continuously monitoring the transformer current and using this information to determine the optimal turn-off timing for the switching transistor on the lagging leg. The control method incorporates a feedback loop that detects the current state and adjusts the turn-off command accordingly, ensuring that the transistor is turned off only when current conditions are favorable. This feedback mechanism improves anti-interference ability and EMC performance by preventing hard switching, while the control complexity remains manageable through straightforward current comparison logic.
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 reduces switching losses, improves the anti-interference ability of the switching transistor, and enhances the electromagnetic susceptibility (EMS) performance by ensuring a small current flows through the switching transistor during turn-off.
Implementation Method 1
a rectifier circuit provided with an LC resonant circuit; determining, after a switching transistor on a leading leg of the phase-shifted full-bridge circuit is turned off, whether a current through the transformer is less than or equal to a preset current value
Data Source
AI summary
A switching tube control method and device, and a direct-current converter. In the solution, after a switching tube on a leading bridge arm in a phase-shifted full-bridge converter is disconnected and a current on a transformer is not greater than a current preset value, a corresponding switching tube on a lagging bridge arm is controlled to be disconnected, and it is ensured that the current flowing through the switching tube is small when the switching tube on the lagging bridge arm is disconnected, such that the soft turn-off of the switching tube on the lagging bridge arm is realized, the loss is reduced, the anti-interference capability of the switching tube is improved, and the EMS performance of the switching tube is improved.