Battery Temperature and SOH Determination via Partial Relaxation Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods fail to accurately determine the temperature and state of health of batteries/cells, which is crucial for optimizing charging sequences and extending battery life, due to limitations in measuring partial relaxation time voltage (VPRT) and correlating it with state of charge (SOC) and temperature.
Innovation Solution
The use of partial relaxation time voltage (VPRT) measured in response to calibration packets, including charge and discharge pulses and rest periods, to determine battery temperature and state of health (SOH) through correlation with known databases or mathematical relationships, allowing for adaptive charging sequences that adjust charging current signals based on these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If partial relaxation time voltage (VPRT) is measured using conventional methods, then measurement simplicity is maintained, but measurement precision deteriorates due to inability to accurately capture voltage during partial relaxation time period
Solution Approach 1:
The charging process is segmented into distinct phases including calibration packets with charge pulses, discharge pulses, and rest periods. The VPRT measurement is specifically performed during the partial relaxation time period that occurs after the discharge pulse and before the next charge pulse, allowing precise temperature determination without requiring complex continuous monitoring throughout the entire charging cycle.
Solution Approach 2:
A calibration packet is applied beforehand to condition the battery and establish a known state before the actual VPRT measurement. This preliminary action ensures that the battery is in a consistent state (with SOC between 5-20%) when the measurement is taken, improving measurement precision while maintaining a relatively simple measurement circuit.
2Measurement precision
If calibration packets with multiple pulses and rest periods are used, then temperature and SOH determination accuracy is improved, but charging time increases due to additional measurement periods
Solution Approach 1:
Instead of performing complete relaxation measurements that would require full rest periods, the invention uses partial relaxation time measurements taken during the natural rest periods that already exist in the charging sequence. By measuring VPRT during the partial relaxation time (after discharge pulse but before next charge pulse), accurate SOH determination is achieved without adding excessive time to the charging process.
Solution Approach 2:
The calibration packets are applied periodically during the charging sequence at predetermined states of charge (e.g., every 10% SOC increment). This periodic application allows temperature and SOH monitoring at critical points without continuously interrupting the charging process, balancing measurement accuracy with charging efficiency.
3Duration of action of stationary object
If adaptive charging sequences are implemented based on real-time temperature and SOH data, then battery longevity is extended, but device complexity increases due to additional control circuitry and algorithms
Solution Approach 1:
The system continuously monitors VPRT during charging and uses this feedback to dynamically adjust charging parameters. The determined temperature and SOH values feed back into the charging control algorithm, which automatically modifies the charging sequence (charge pulse duration, discharge pulse timing, rest period length) to optimize battery life while maintaining a relatively simple control structure based on predetermined SOC thresholds.
Solution Approach 2:
The charging sequence is made dynamic by adjusting charge and discharge pulse characteristics based on real-time battery state. As SOC increases and approaches critical thresholds (5%, 20%, 80%, 95%), the system dynamically modifies the calibration packet parameters and charging current, allowing extended battery life through adaptive control without requiring overly complex real-time optimization algorithms.
Data Source
AI summary
Techniques and circuitry, in one embodiment, determine a temperature of a battery by applying a calibration packet to the battery's terminals and at the battery's first SOC, wherein the calibration packet includes a first pulse (charge or discharge) which temporally precedes a rest period. In one embodiment, measurement circuitry measures a first terminal voltage at a time immediately prior to or at a beginning of the first pulse of the calibration packet, and a second terminal voltage, in response to the calibration packet, at a time during the partial relaxation time period of a battery. Control circuitry determines a partial relaxation time voltage (VPRT) at the battery's first SOC using the first and second terminal voltages and determines a temperature of the battery by correlating the VPRT at the first SOC to a temperature of the battery at the battery's current SOH.