Battery SOC Estimation Using Temperature-Based Discharge Endpoints
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Solution Overview
Problem
Existing methods for calculating the state of charge (SOC) of batteries fail to accurately account for rapid temperature changes, leading to discrepancies between calculated and actual SOC.
Innovation Solution
A method involving a processor that calculates the SOC of a battery, obtains its temperature, and determines a specific SOC associated with a discharge endpoint based on temperature changes, thereby adjusting the SOC change trend to reflect actual battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the SOC is calculated based on voltage change using a lookup table, then the calculation is simple and fast, but the accuracy deteriorates when temperature changes rapidly
Solution Approach 1:
The patent pre-calculates temperature-SOC relationships and stores them in lookup tables before operation. During battery discharge, the system retrieves pre-computed temperature data corresponding to different SOC levels and applies compensation based on actual temperature measurements, eliminating the need for complex real-time thermal modeling while maintaining accuracy
Solution Approach 2:
The patent introduces temperature as an additional parameter to modify the SOC calculation. Instead of relying solely on voltage-SOC relationships, the system uses temperature-SOC lookup tables to determine correction factors that adjust the nominal SOC value, transforming a single-parameter calculation into a multi-parameter compensation model
2Quantity of substance
If the battery is discharged until voltage reaches final discharge voltage, then maximum capacity is utilized, but temperature may exceed threshold causing safety issues
Solution Approach 1:
The patent predicts future temperature evolution during discharge by referencing pre-computed temperature-SOC trajectories stored in lookup tables. Before temperature exceeds the threshold, the system identifies the SOC level at which temperature will reach the limit and adjusts the discharge endpoint accordingly, preventing thermal runaway while maximizing safe capacity utilization
Solution Approach 2:
The patent implements a feedback mechanism that continuously monitors actual battery temperature during discharge and compares it with predicted temperature values from the lookup tables. When the actual temperature approaches the threshold, the system dynamically adjusts the discharge termination SOC to ensure temperature remains within safe limits
3Measurement precision
If the SOC change trend is adjusted based on temperature, then accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent pre-computes temperature-SOC relationships and stores them in lookup tables during the design phase. During operation, the system only needs to perform simple table lookups based on current temperature and SOC values, then apply pre-calculated correction factors, avoiding complex real-time thermal simulations while achieving accurate temperature-compensated SOC estimation
Data Source
AI summary
A method of calculating a state of charge of a battery, includes: calculating, by at least one processor, a state of charge (SOC) of a battery; obtaining, by the at least one processor, a temperature of the battery; calculating, by the at least one processor, based on the obtained temperature, a plurality of temperatures associated with a plurality of SOCs of the battery that are gradually downgraded from the calculated SOC of the battery by a grade; determining, by the at least one processor, based on the calculated plurality of temperatures, a specific SOC associated with a discharge end point of the battery; and determining, by the at least one processor, based on the determined specific SOC, a change trend of the SOC of the battery.