Battery Pack Cutoff Voltage Control for Over-Discharge Detection
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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 voltage measurement function from individual cell-level measurements to pack-level total voltage measurement. By combining multiple measurement functions (total voltage, total current, temperature) into a single monitoring unit, the system prevents over discharge without requiring individual voltage detecting lines for each cell, thus reducing sensor element complexity while maintaining reliability
Solution Approach 2:
The monitoring unit is designed with multi-functionality, measuring total voltage, total current, and temperature simultaneously. This universal monitoring approach replaces the need for multiple dedicated voltage sensors for each cell, achieving over discharge prevention through comprehensive pack-level monitoring rather than individual cell monitoring
2Measurement precision
If individual voltage sensors are installed for each battery cell, then accurate cell voltage measurement is achieved, but the number of sensors increases
Solution Approach 1:
The patent combines multiple measurement functions into a single monitoring unit that measures total voltage, total current, and temperature. This merging approach reduces the quantity of sensors from multiple individual voltage sensors to a single multi-functional monitoring unit, while still enabling accurate over discharge detection through capacity condition calculation
Solution Approach 2:
The system uses a simplified monitoring approach that copies the essential monitoring function at the pack level rather than replicating individual cell monitoring. By creating a pack-level model of battery behavior based on total measurements, the system achieves the necessary monitoring precision with fewer sensors
Data Source
AI summary
A battery system that 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.