Battery Pack Cell Monitoring via Overlapping Group Measurements
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Solution Overview
Problem
Existing battery management systems for monitoring battery cells in vehicle energy storage systems are complex, time-consuming, and costly, particularly in estimating state of charge (SOC) and state of health (SOH), and detecting abnormal conditions such as over-voltage and under-voltage.
Innovation Solution
The method involves arranging battery cells into groups with overlapping cells and connecting them to a sensor unit, using an over-determined equation system to recalculate cell measurements, reducing the number of required sensors and computational workload, and implementing a hierarchical model to minimize sensor units and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If battery cells are monitored individually with separate sensors for each cell, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The battery pack is divided into multiple groups, with each group containing multiple battery cells. A sensor unit measures the total voltage of each group, and individual cell voltages are calculated by subtracting the voltages of other cells in the same group. This segmentation approach reduces the number of sensors needed while maintaining measurement precision through mathematical decomposition.
Solution Approach 2:
The patent introduces an intermediate calculation method using group voltage measurements as mediators. Instead of directly measuring each cell voltage with separate sensors, the system uses group voltage measurements as intermediaries to derive individual cell voltages through subtraction and calculation, reducing sensor requirements while preserving measurement accuracy.
2Device complexity
If the number of sensors is reduced to lower cost, then device complexity decreases, but measurement precision and fault detection capability deteriorate
Solution Approach 1:
The battery pack is divided into multiple groups, with each group containing multiple battery cells. A sensor unit measures the total voltage of each group, and individual cell voltages are calculated by subtracting the voltages of other cells in the same group. This segmentation approach reduces the number of sensors needed while maintaining measurement precision through mathematical decomposition.
Solution Approach 2:
The patent measures group voltages (excessive action) rather than individual cell voltages directly, using these partial measurements to derive complete information about all cells through calculation. This approach uses more measurement data than strictly necessary for individual cells, enabling both cost reduction and maintained precision.
3Reliability
If state of charge estimation methods are made more accurate, then reliability improves, but computational load and time consumption increase
Solution Approach 1:
The patent pre-calculates and stores the relationship between group voltages and individual cell voltages, establishing calculation formulas in advance. During operation, the system only needs to substitute measured group voltage values into these pre-established formulas, significantly reducing real-time computational load while maintaining accurate state of charge estimation.
Data Source
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AI summary
The invention relates to a method for monitoring the status of a plurality of battery cells (C1-C5) in a battery pack (1), said method comprising: arranging said battery cells (C1-C5) in at least two groups (G1-G3) of cells; connecting said groups (G1- G3) of cells to a sensor unit (7b); and obtaining, by means of said sensor unit (7b), at least one sensor measurement (U1 sens, U 2 sens, U 3 sens ) for each group (G1-G3) which is indicative of the state of operation of said battery pack (7a). The method according to the invention further comprises: determining a cell measurement (U1 cell, U 2 cell, …) for each battery cell (C1-C5) by means of an over-determined equation system which defines said cell measurement (U1 cell, U 2 cell, …) as a function of said sensor measurement (U1 sens, U 2 sens, U 3 sens ); and evaluating any residual terms resulting from said equation system in order to identify any battery 1 cell having a cell measurement (U cell ) which deviates from an expected value based on the remaining battery cells. The invention also relates to a battery management system (12) for monitoring the status of a plurality of connected battery cells (C1-C5) as mentioned above.