PTC Bus-Bar Assembly for Battery Over-Load Protection
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Solution Overview
Problem
Existing over-load protection systems for power batteries in electric vehicles are complex, prone to failure, and pose safety risks due to reliance on software-controlled current limiting and mechanical fuse protection, which can lead to misjudgment and hidden safety hazards.
Innovation Solution
A bus-bar assembly with a PTC unit connected between battery cells, providing a physical over-load protection system that functions independently of software control, complementing existing fuse and current limiting protection systems, with adjustable thermal-protective coatings and insulation to enhance sensitivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software-controlled current limiting protection is used, then over-load protection can be provided, but the control process becomes long and complicated with higher risk of failure
Solution Approach 1:
The patent replaces the software-controlled electrical control system with a physical PTC (positive temperature coefficient) component that automatically limits current based on temperature. The PTC component's resistance increases sharply at a predetermined temperature, providing automatic current limiting without requiring BMS detection, VCU processing, or actuator control, thus eliminating software control complexity and improving reliability
Solution Approach 2:
The PTC component performs self-protection by automatically increasing its resistance when it reaches a predetermined temperature due to excessive current. This self-regulating mechanism eliminates the need for external control systems, sensors, and processing units, providing a simple yet reliable over-load protection that requires no external intervention or monitoring
2Reliability
If fuse protection is used, then mechanical circuit break can be achieved, but the fuse holder generates a lot of heat causing direct melting of the fuse
Solution Approach 1:
The patent changes the protection mechanism from direct thermal melting (fuse) to resistive switching based on temperature (PTC). Instead of relying on heat generation to melt the fuse, the PTC component detects temperature rise and switches from low resistance to high resistance state, limiting current before excessive heat can melt protective components. This parameter change from thermal-mechanical to electro-resistive protection reduces temperature stress on the fuse holder
3Reliability
If PTC unit is added to bus-bar assembly, then fail-safe physical current limitation is achieved, but device structure becomes more complex
Solution Approach 1:
The patent merges the PTC protection component directly with the bus-bar assembly structure, integrating the protective function into the existing current-carrying pathway. The PTC unit is positioned within the bus-bar assembly and electrically connected in series with the battery cells, combining the connection function and protection function into a single integrated structure rather than adding a separate external protection device
Solution Approach 2:
The bus-bar assembly is designed to serve multiple functions: electrical connection between battery cells and over-load protection through the integrated PTC unit. This multi-functional design eliminates the need for separate protection devices and reduces overall system complexity by making the bus-bar assembly both a connector and a protective element
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 PTC-based over-load protection system offers improved safety and stability by providing a fail-safe, physical means of current limitation, preventing fuse melting and ensuring continuous operation even under extreme conditions.
Implementation Method 1
a PTC unit connected between the first connection arm and the second connection arm
Data Source
AI summary
The invention provides a bus-bar assembly, a power battery over-load protection system and method, as well as a power battery assembly, wherein the bus-bar assembly comprises a first connection arm having one or more connection ends so as to be connected to an upstream battery cell; a second connection arm having one or more connection ends so as to be connected to a downstream battery cell; and a PTC unit connected between the first connection arm and the second connection arm. The bus-bar assembly, the over-load protection system, the power battery assembly and the vehicle or the like according to the invention has better safety and stability.