Battery Cell Balancing Circuit for Accurate Voltage Detection
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Solution Overview
Problem
Conventional battery management devices face challenges in reducing voltage detection errors due to voltage drops in voltage detection lines, which affects the accuracy of cell voltage detection and subsequently impacts charging and discharge control of the battery.
Innovation Solution
The battery management device employs multiple voltage detection circuits and discharge circuits connected via pairs of voltage detection lines. A voltage difference acquisition unit and a cell balancing control unit work together to identify battery cells with voltage differences within specific thresholds and discharge them accordingly, either when the vehicle is stopped or in operation, to minimize the impact of voltage drops on detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equalization control is performed by discharging battery cells through discharge circuits, then cell voltage equalization is achieved, but voltage detection accuracy deteriorates due to voltage drops in shared voltage detection lines
Solution Approach 1:
The patent segments the voltage detection and discharge functions by introducing separate detection lines for each battery cell. Each voltage detection circuit has its own dedicated detection lines connected to the corresponding battery cell, separating the detection path from the discharge path. This segmentation prevents the discharge current from affecting the voltage detection accuracy while still enabling effective equalization control.
2Device complexity
If discharge circuits are connected in parallel with battery cells via shared voltage detection lines, then device complexity is reduced, but voltage detection error increases due to current-induced voltage drops
Solution Approach 1:
The patent divides the circuit into separate detection and discharge paths. Each battery cell has dedicated detection lines for voltage measurement and separate discharge circuits for equalization. This segmentation eliminates the interference between detection and discharge operations while maintaining manageable system complexity through modular circuit design.
Solution Approach 2:
The patent introduces separate detection lines as intermediary pathways between the battery cells and the voltage detection circuits. These intermediary lines carry only the voltage signal without carrying discharge current, thereby mediating between the need for simple circuit connection and the requirement for accurate voltage detection during equalization operations.
3Ease of manufacture
If voltage detection lines have electrical resistance, then voltage drop occurs during discharge, but increasing line resistance would simplify circuit design
Solution Approach 1:
The patent segments the electrical pathways so that detection lines and discharge paths are separate. The detection lines are designed with minimal resistance for accurate voltage measurement, while discharge circuits use separate pathways with appropriate resistance for current control. This segmentation allows each circuit to be optimized for its specific function without compromising the other.
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 effectively reduces the influence of voltage detection accuracy reduction, allowing for accurate equalization of battery cell voltages while ensuring proper charging and discharge control, even during vehicle operation.
Implementation Method 1
a voltage drop occurs in voltage detection lines due to the electrical resistance of the voltage detection lines
Implementation Method 2
Each discharge circuit is provided between adjacent two voltage detection lines, and is connected in parallel with a corresponding one of the cells
Data Source
AI summary
A battery management device that manages a battery includes: multiple voltage detection circuits each connected to a corresponding one of a plurality of battery cells; and multiple discharge circuits each connected to a corresponding one of the battery cells. The battery management device causes the battery cell whose voltage difference from a reference voltage is equal to or greater than a predetermined first threshold and less than a second threshold that is greater than the first threshold to be discharged while a system of the vehicle is stopped, and causes the battery cell whose voltage difference is equal to or greater than the second threshold to be discharged at least either while the system is stopped or while the system is in operation.