Estimating Cell Voltage Excursion During Battery Pack Sensing Faults
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Solution Overview
Problem
In battery packs, sensing faults that result in unavailable cell voltage data for two cells lead to inaccurate monitoring by the controller, causing the battery pack to be disabled, which is inconvenient and can disrupt system functionality.
Innovation Solution
A method to estimate cell voltage excursion by detecting sensing faults, calculating average cell voltages for known cells, and assigning estimated values to missing cells, allowing for selective enabling or disabling of battery pack functionality, including limited key cycles to facilitate necessary maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery pack is disabled due to sensing faults with two missing cells, then safety is ensured by preventing inaccurate monitoring, but operational continuity is lost causing inconvenience and system disruption
Solution Approach 1:
The patent introduces an intermediary estimation process that uses block voltage measurements and average cell voltage calculations to bridge the gap between missing individual cell data and the need for safe monitoring. This intermediary approach allows the system to infer missing cell voltages through mathematical relationships rather than direct measurement, enabling continued operation while maintaining safety oversight.
Solution Approach 2:
The patent creates a virtual copy or representation of the missing cell voltage data through estimation algorithms. Instead of requiring actual direct measurements from faulty sensors, the system generates estimated voltage values that replicate the information needed for safe operation, allowing the battery management system to function as if complete data were available.
2Measurement precision
If conventional control actions disable the battery pack in response to sensing faults, then accurate monitoring is maintained, but system functionality is lost requiring immediate service
Solution Approach 1:
The patent applies partial action by implementing a tiered response to sensing faults. Rather than completely disabling the system upon detecting any fault, the estimation approach allows partial functionality to continue with monitored uncertainty. The system performs sufficient monitoring to ensure safety while accepting that complete precision is unavailable, enabling operation with reduced but adequate measurement capability.
3Measurement precision
If individual cell voltages are measured for each battery cell, then accurate state monitoring is achieved, but system complexity increases with more sensors and wiring
Solution Approach 1:
The patent merges individual cell measurement requirements into a block-level measurement approach. By measuring the total voltage of a block containing multiple cells and combining this with measurements from available individual cells, the system reduces the number of separate measurement circuits needed while still enabling inference of individual cell states through mathematical relationships.
Data Source
AI summary
A method and system are disclosed for estimating cell voltage excursion in a battery pack in the presence of a sensing fault in which actual cell voltages of first and second battery cells in a block of battery cells become unknown or missing. The sensing fault is detected, and a cell voltage is determined for each cell in the block other than the first and second cells. The method also includes measuring a block voltage, calculating an average cell voltage in the block, and estimating that the first cell is equal to the calculated average cell voltage. All excursion or deviation of the measured block voltage from a sum of the cell voltages and the estimated cell voltage of the first cell is assigned to the second cell. A control action is executed using the estimated cell voltages, including selectively enabling or disabling functionality of the battery pack.