DC-DC Converter Synchronous Rectification Without Dead Time
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Solution Overview
Problem
Existing DC-DC converters experience overvoltage issues during switching operations due to the interruption of current loops in synchronous rectifier circuits, particularly when switch elements are complementarily switched with dead time.
Innovation Solution
A voltage converter design that includes a DC-DC converter with complementary switching of synchronous rectification switches without dead time, utilizing a controller to manage the duty ratio and operation modes of main and clamp switches, along with synchronous rectification switches, to prevent overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complementary switching of synchronous rectification switches is performed with dead time to prevent short circuit, then switching safety is improved, but current loop interruption occurs causing overvoltage
Solution Approach 1:
The patent applies the continuity of useful action principle by ensuring that at least one synchronous rectification switch remains conductive during the dead time period. This is achieved through body diode conduction paths that maintain current flow continuity, preventing the harmful interruption of the current loop while still allowing complementary switching for safety.
Solution Approach 2:
The patent uses the body diodes of the synchronous rectification switches as intermediary elements during the dead time. These body diodes provide alternative conduction paths that maintain current flow when the main switch channels are turned off, acting as mediators that prevent overvoltage while enabling safe switching transitions.
2Reliability
If synchronous rectification switches are turned off during dead time to prevent short circuit, then switching safety is improved, but power conversion efficiency decreases due to current loop interruption
Solution Approach 1:
The patent maintains continuous useful action by ensuring current flow persists through body diode conduction during the dead time period. This prevents energy loss from current loop interruption while still achieving the safety benefits of turning off main switches, thereby maintaining high power conversion efficiency.
3Reliability
If dead time is introduced for complementary switching, then switch element protection is improved, but switching speed and response time decrease
Solution Approach 1:
The patent achieves continuous current flow during dead time through body diode conduction, which minimizes the effective interruption period. This approach maintains switch element protection while reducing the impact on switching speed, as the current path remains active rather than being completely interrupted.
Solution Approach 2:
The patent converts the potentially harmful effect of dead time (current loop interruption) into a beneficial configuration where body diodes provide controlled conduction paths. This transforms the dead time period from a harmful interruption into a controlled transition phase that maintains current flow while still providing switch protection.
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
Prevents overvoltage during switching operations by ensuring continuous current flow through synchronous rectifier circuits, enhancing stability and efficiency without the need for additional sensors.
Implementation Method 1
a transformer, a main switch connected to an input terminal and the transformer, and first and second synchronous rectification switches connected to an output terminal and the transformer
Data Source
AI summary
An embodiment voltage converter includes a DC-DC converter and a controller. The DC-DC converter includes a transformer, a main switch connected to an input terminal and the transformer, and first and second synchronous rectification switches connected to an output terminal and the transformer, and the controller is configured to switch the main switch so that the DC-DC converter adjusts a voltage of the input terminal and outputs the voltage to the output terminal and to complementarily switch the first and second synchronous rectification switches without dead time.