Battery Module Cell Voltage Estimation for Sensor Fault Operation
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Solution Overview
Problem
In electric vehicles, when a battery cell's voltage cannot be measured due to a fault, the entire battery system is often shut down for safety reasons, leading to reduced driving capabilities and potential safety risks, especially in autonomous vehicles that cannot safely navigate to a stop.
Innovation Solution
A method that estimates the voltage of unmeasurable battery cells by using pre-measured values and average cell voltage calculations, allowing the battery module to continue operating by classifying cells as good, neutral, or bad based on threshold values, preventing overcharging or deep discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery system is shut down when a cell voltage cannot be measured, then safety is ensured, but driving capability is reduced
Solution Approach 1:
The patent applies preliminary action by determining and storing the last valid cell voltage values before a measurement failure occurs. When a measuring line failure is detected, the system uses these pre-stored values combined with average voltage calculations from functioning cells to estimate the unmeasurable cell's voltage, enabling continued operation without immediate shutdown.
Solution Approach 2:
The patent introduces an intermediary estimation mechanism that bridges the gap between measured and unmeasurable cell voltages. By calculating average voltages from healthy cells and using this as an intermediary reference, the system can infer the state of failed cells, allowing the battery module to maintain operation rather than shutting down completely.
2Productivity
If the battery module continues operating with unmeasurable cell voltage, then driving capability is maintained, but safety risk increases
Solution Approach 1:
The patent implements feedback by continuously monitoring the estimated cell voltages and comparing them against threshold values. The system calculates average voltages from measurable cells and uses this feedback to update estimates for unmeasurable cells, while also monitoring whether estimated values indicate dangerous states such as overcharging or deep discharge conditions.
Solution Approach 2:
The patent applies partial action by implementing selective monitoring and estimation only for affected cells while maintaining normal operation of the entire battery module. Rather than shutting down all cells, the system partially compensates for measurement failures by estimating only the specific unmeasurable cells' voltages based on average calculations from functioning cells.
3Measurement precision
If additional hardware is added to improve voltage measurement reliability, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies copying by creating virtual representations of unmeasurable cell voltages through estimation algorithms. Instead of adding physical measurement hardware for each cell, the system copies the measurement approach by calculating representative voltage values from measurable cells and using these to infer the state of unmeasurable cells, thereby maintaining measurement coverage without additional hardware.
Data Source
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AI summary
The invention relates to a method for operating a battery module having multiple battery cells (2), comprising the following steps: a) determining the cell voltages (US) of the individual battery cells (2) at a starting time; b) determining an average cell voltage (MS) from the cell voltages (US) of the battery cells (2) at the starting time; c) estimating the cell voltage of at least one battery cell (2) at an operating time if the cell voltage of the battery cell (2) is not measurable at the operating time, wherein, when estimating the cell voltage of the battery cell (2) at the operating time, the cell voltage (US) of the battery cell (2) determined at the starting time, the average cell voltage (MS) determined at the starting time, and an average cell voltage determined at the operating time are taken into account, wherein the average cell voltage determined at the operating time is determined from the cell voltages of the remaining battery cells (2) measured at the operating time.