Battery Pack Cutoff Voltage Shift Without Per-Cell Sensing
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Solution Overview
Problem
Existing battery systems require complex sensor elements to prevent over discharge, as they need to measure voltage between each battery cell, leading to increased complexity.
Innovation Solution
A battery system with a monitoring unit that measures total voltage, current, and temperature, and a control unit that calculates and adjusts the discharge cutoff voltage based on these parameters to prevent over discharge without individual voltage sensors for each cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage detecting lines are provided for each battery cell to measure individual cell voltages, then over discharge can be prevented, but the sensor elements become complicated
Solution Approach 1:
The patent merges the monitoring function from individual cell level to pack level by measuring total voltage across all series-connected battery cells using a single voltage sensor. This consolidation reduces the number of sensors from N (one per cell) to 1 (one for the entire pack), directly resolving the contradiction between reliable over discharge prevention and simplified sensor elements.
Solution Approach 2:
The patent makes the total voltage measurement serve multiple functions: it monitors the overall pack voltage for over discharge detection, works in conjunction with current and temperature sensors for comprehensive pack health monitoring, and enables estimation of individual cell conditions through calculation. This multi-functionality compensates for the reduced sensor count while maintaining safety.
2Measurement precision
If individual voltage measurement per cell is implemented, then precise cell monitoring is achieved, but the number of sensors and detecting lines increases
Solution Approach 1:
The patent combines multiple measurement functions into a single sensor setup by measuring the aggregate voltage of the entire battery pack rather than individual cell voltages. This reduces the quantity of sensors from N individual voltage sensors to 1 total voltage sensor, directly addressing the contradiction between measurement precision and sensor quantity.
Solution Approach 2:
The patent introduces current and temperature sensors as intermediary measurement tools that, when combined with total voltage measurement and computational processing, enable indirect monitoring of individual cell conditions. This mediator approach allows comprehensive cell-level insight without requiring direct voltage measurement from each cell, thus reducing sensor quantity while maintaining monitoring capability.
Data Source
AI summary
A battery system avoids an over discharge with a simple sensor element is provided. The battery system comprises: a battery pack including a plurality of battery cells connected in series, a monitoring unit that monitors a condition of the battery pack, and a control unit that controls a discharge of the battery pack. The control unit calculates capacity condition A of the battery pack at a first discharge cutoff voltage based on the total voltage and the total current, estimates capacity condition B of the battery pack at the first discharge cutoff voltage based on the total current and the temperature, determines an occurrence of an over discharge based on the capacity condition A and the capacity condition B, changes the first discharge cutoff voltage to a second discharge cutoff voltage that is higher than the first discharge cutoff voltage, when the occurrence of the over discharge is determined.