Active Avalanche Protection for Flyback Converter Switches
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Solution Overview
Problem
Power switches in converters face avalanche effects due to high voltages, leading to malfunctions and increased costs from over-dimensioning to prevent these effects, as well as additional losses from protection circuits.
Innovation Solution
A controller is used to detect break-through situations in power switches by monitoring current signals and generating control signals to manage the state of the power switch, allowing for reduced operational margins and optimized protection circuit parameters, thereby reducing costs and losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power switches are over-dimensioned to avoid avalanche effects, then reliability is improved, but cost increases
Solution Approach 1:
The controller performs preliminary detection of avalanche situations by monitoring current signals before actual damage occurs. This allows the system to take preventive action (reducing input voltage) before the power switch fails, enabling the use of power switches with smaller operational margins while maintaining reliability.
Solution Approach 2:
The system implements feedback by continuously monitoring the current signal through the power switch and using this information to detect avalanche situations. Based on this feedback, the controller adjusts the input voltage to prevent damage, allowing power switches to operate closer to their limits without compromising reliability.
2Reliability
If protection circuits are added to protect power switches, then reliability is improved, but power losses increase
Solution Approach 1:
The invention extracts the protection function from traditional passive protection circuits (snubbers) and implements it actively through the controller's detection and response mechanism. By removing the need for energy-dissipating snubber circuits and replacing them with active monitoring and voltage reduction, power losses are significantly reduced while maintaining protection capability.
Solution Approach 2:
The invention replaces the mechanical/passive protection approach (snubber circuits that dissipate energy) with an electronic control approach. The controller uses electronic sensing and control to prevent avalanche situations, substituting energy-dissipating passive protection with energy-efficient active protection.
3Reliability
If protection circuits are over-dimensioned to ensure safe operation, then reliability is improved, but cost increases
Solution Approach 1:
The controller performs preliminary detection of avalanche conditions before they cause damage, allowing the system to take preventive action. This enables the use of minimally dimensioned protection circuits that are sufficient for actual operating conditions rather than worst-case scenarios, reducing cost while maintaining safety.
Solution Approach 2:
The system dynamically changes operating parameters (input voltage) based on detected conditions. By reducing the input voltage when avalanche situations are detected, the system adapts protection requirements to actual operating conditions, allowing for cost-optimized protection circuit design rather than over-dimensioning for worst-case scenarios.
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
The system enables power switches to operate near their limits, reducing costs and power losses by detecting and managing avalanche situations, increasing the lifetime of power converters, and allowing for more efficient design of protection circuits.
Implementation Method 1
The submission to high voltages may cause avalanche effects within the power switches, which may eventually lead to a malfunction of the power switches and the power converters. The controller is configured to detect a break-through situation of the power switch by detecting that the sensed current signal is greater or equal to a current threshold, when the power switch is in off-state.
Data Source
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AI summary
The present document relates to power converters. In particular, the present document relates to the protection of the power switches of power converters. A controller (306) configured to control a switched-mode power converter (305) is described. The controller (306) comprises a control pin for controlling a state of a power switch (202) of the switched-mode power converter (305) using a control signal (232); and a sensing pin for receiving a sensed current signal (233) indicative of a current through the power switch (202). The controller (306) is configured to detect a break-through situation of the power switch (202) based on the state of the power switch (202) and based on the sensed current signal (233).