Battery Management Device Cell Voltage Detection Accuracy
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Solution Overview
Problem
Accurate detection of cell voltage in lithium ion battery systems is challenging due to voltage drops at connection members, leading to errors in voltage measurement and potential misinterpretation of cell health.
Innovation Solution
A management device with a voltage detection circuit connected to each cell node and the connection member, using resistors and diodes to distinguish between cell voltages and connection member voltages, and a control circuit to recognize and differentiate these voltages, preventing incorrect equalization control and abnormality detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage detection lines are connected to each cell node through connection members, then cell voltage can be detected, but voltage drop at connection members causes detection errors
Solution Approach 1:
The patent introduces a management device as an intermediary component that includes a voltage detection circuit and control circuit. This intermediary detects the voltage at both ends of the connection member and calculates the voltage drop, then compensates for this error when determining cell voltages, thereby eliminating the harmful effect of connection member voltage drop on detection accuracy
Solution Approach 2:
The control circuit continuously monitors the voltage at both ends of the connection member and uses this feedback information to calculate and compensate for voltage drop errors in real-time, improving the accuracy of cell voltage detection by dynamically adjusting for connection member effects
2Measurement precision
If separate voltage detection circuits are used for each cell module to avoid connection member interference, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The patent merges the voltage detection functions for multiple cell modules into a single management device. The voltage detection circuit detects voltages at multiple nodes, and the control circuit processes all these signals centrally, calculating connection member voltage drops and compensating for errors across all cells, thereby reducing device complexity while maintaining detection accuracy
Solution Approach 2:
The management device performs multiple functions: it detects voltages at all cell nodes, identifies which voltages correspond to connection members versus cells, calculates voltage drop errors, and compensates for these errors to determine accurate cell voltages. This multi-functional approach eliminates the need for separate detection circuits for each module
Data Source
AI summary
A management device manages an electricity storage module having: a first cell module and a second cell module each including a plurality of cells connected in series; and a conductive connection member for connecting the first cell module and the second cell module in series. A voltage detection circuit is connected to the nodes of the respective cells through voltage detection lines to detect the voltage of each of the cells and the voltage at both ends of the connection member. A control circuit distinguishes between and recognizes the voltage of each of the cells and the voltage at both ends of the connection member, which are detected by the voltage detection circuit.