Flying-Capacitor DC-DC Converter Fault Current Blocking
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Solution Overview
Problem
Existing DC-DC converters face issues with high switch unit prices due to the need for higher rated voltages, and existing protection mechanisms like fuses and relay switches are ineffective in preventing switch damage during faults, leading to high replacement costs.
Innovation Solution
A DC-DC converter with a protection circuit that includes capacitors and diodes to step-down output voltage and block fault current, using switches with rated voltages lower than the charging voltages of the capacitors to prevent switch damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If switches with higher rated voltage are used to obtain larger output voltage, then the output voltage capability is improved, but the unit price of switches increases
Solution Approach 1:
The patent divides the high voltage switching function into multiple segments by using multiple switches with lower rated voltages connected in series. Each switch handles a portion of the total voltage, allowing the system to achieve high output voltage capability while using affordable, lower-voltage-rated switches individually.
2Reliability
If relay switch is used for protection, then the protection function is provided, but the response speed is slow and cannot quickly cut off fault current
Solution Approach 1:
The patent replaces the mechanical relay switch protection system with an electronic protection circuit that uses fast-acting electronic switches and control logic. This electronic system responds much faster to fault conditions, quickly cutting off fault current before it can damage the switches, while maintaining the protection function.
3Reliability
If fuse is used for protection, then the protection function is provided, but the fuse is disposable and must be replaced every time a fault occurs, resulting in high replacement cost
Solution Approach 1:
The patent implements a reusable electronic protection circuit that automatically detects and responds to fault conditions without requiring external replacement. The protection circuit can reset and continue operation after clearing a fault, eliminating the need for disposable fuses and reducing maintenance costs.
4Power
If multi-level converter with flying capacitor is used, then high output voltage is obtained using low voltage switches, but fault current can still damage the switches when short circuit occurs
Solution Approach 1:
The patent incorporates a protection circuit that is pre-configured and ready to act immediately upon detecting fault conditions. The protection circuit includes clamping diodes and control logic that are already in place to redirect or limit fault current before it can reach damaging levels, proactively protecting the switches rather than reacting after damage occurs.
Data Source
AI summary
A DC-DC converter can include a driving circuit comprising a switch part and a flying capacitor configured to convert an input voltage of an input side into an output voltage of an output side, and a protection circuit configured to be connected to the output side. The protection circuit can be configured to block the fault current flowing to the switch part by lowering the output voltage step by step when a fault occurs.