Battery Management Device for Redundant Voltage Detection Line Disconnection
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Solution Overview
Problem
Existing power supply systems for lithium ion batteries struggle to accurately detect disconnections in voltage detection lines, particularly in redundant configurations, which can lead to inaccurate state-of-charge management and equalization control, and require additional circuits for failure detection.
Innovation Solution
A management device with a first and second voltage detection circuit connected to each node of serially connected cells, where the lowest node is connected with two voltage detection lines and a negative power supply line, and the second voltage detection circuit shares a single negative power supply line, allowing for easy detection of disconnections without additional special circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage detection lines are separately wired from power supply lines, then detection accuracy is maintained, but wiring complexity increases
Solution Approach 1:
The patent segments the voltage detection function and power supply function into separate circuits (first voltage detection circuit and second voltage detection circuit). This allows the first circuit to use dedicated voltage detection lines for high accuracy, while the second circuit shares the power supply lines, thus resolving the contradiction between detection accuracy and wiring complexity.
2Reliability
If redundant voltage detection circuits are implemented, then system reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the power supply function into both the first and second voltage detection circuits by connecting them to the same power supply lines. This allows redundancy in voltage detection while sharing common resources (power supply lines), thereby improving reliability without proportionally increasing circuit complexity.
Solution Approach 2:
The second voltage detection circuit is designed to serve multiple purposes: it can detect voltage under normal conditions and also detect disconnections in the voltage detection lines by monitoring its own power supply lines. This multi-functionality reduces the need for separate detection mechanisms, thus improving reliability without excessive complexity increase.
3Difficulty of detecting and measuring
If voltage detection line disconnection is detected by observing voltage change, then detection capability is achieved, but additional circuits are required
Solution Approach 1:
The second voltage detection circuit uses its own power supply lines to detect disconnections. When a disconnection occurs in the voltage detection lines, the terminal voltage of the second circuit changes, providing self-diagnostic capability without requiring external detection circuits. This resolves the contradiction by achieving detection capability while avoiding additional circuits.
Data Source
AI summary
In order to easily detect a disconnection in a lowest-order voltage detection line when a voltage detection circuit for detecting the respective voltage of a plurality of serially connected cells is made redundant, the operation power supply of a first voltage detection circuit and a second voltage detection circuit is fed from both ends of a plurality of serially connected cells. The lowest node of the plurality of cells and the first voltage detection circuit are connected by the two lines of a voltage detection line and a negative power supply line. The lowest node of the plurality of cells and the second voltage detection circuit are connected by a single wire serving as both of a voltage detection line and a negative power supply line.