Integrated DC-DC Battery Protection With Liquid-Cooled FETs
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Solution Overview
Problem
Current DC-DC converters in electrified vehicles require multiple air-cooled FETs for peak current handling and dual batteries for short circuit protection, leading to increased costs, size, and weight, while traditional solid-state relays pose safety hazards due to potential system failures.
Innovation Solution
A DC-DC converter with integrated low voltage battery protection using two liquid-cooled FETs and protection circuitry that detects voltage and current drops to mitigate hazards, eliminating the need for additional FETs and secondary batteries, and incorporating a protection circuit to manage overcharge and reverse voltage during jump starting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple air-cooled FETs are used in parallel to handle peak currents, then the current handling capability is improved, but the device complexity, size, and weight increase
Solution Approach 1:
The patent merges the functions of multiple FETs into a single FET by integrating the low voltage battery protection directly into the DC-DC converter. This eliminates the need for parallel FET configurations, reducing device complexity while maintaining current handling capability through the integrated protection circuitry.
Solution Approach 2:
The single FET in the integrated protection circuit is designed to perform multiple functions: it handles peak currents, provides short circuit protection, and enables the battery to support both 12V buses during faults. This multi-functionality replaces the need for multiple specialized FETs.
2Reliability
If dual batteries and dual DC-DC converters are employed for short circuit protection, then the system reliability is improved, but the cost and device complexity increase
Solution Approach 1:
The patent combines the short circuit protection function with the existing DC-DC converter and single low voltage battery by integrating protection circuitry. This eliminates the need for dual batteries and dual DC-DC converters, reducing system complexity while maintaining reliability through the integrated protection mechanisms.
Solution Approach 2:
The integrated protection circuit enables the single low voltage battery to serve itself and the system by automatically detecting faults and switching to support both 12V buses when needed, eliminating the need for redundant backup systems.
3Reliability
If traditional solid-state relays are used for battery protection, then the protection function is provided, but safety hazards arise from potential system failures
Solution Approach 1:
The patent extracts the protection function from the traditional solid-state relay and integrates it directly into the DC-DC converter control circuitry. This eliminates the intermediate relay component that could fail, providing more reliable protection without safety hazards.
Solution Approach 2:
The patent replaces the mechanical/electromechanical relay system with an integrated electronic protection circuit that uses voltage and current sensing to detect faults and control the FET switching. This solid-state integration eliminates mechanical failure modes and improves safety.
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 configuration reduces the number of high current FETs, eliminates the need for secondary batteries and DC-DC converters, and enhances reliability and safety by preventing system failures at lower costs, while maintaining support for dual buses and reducing heat management needs.
Implementation Method 1
A DC-DC converter with integrated low voltage battery protection using two liquid-cooled FETs
Data Source
AI summary
A DC-DC with integrated low voltage battery protection is disclosed.