Battery SOC Tail-End Calibration to Prevent Charge State Jumps
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Solution Overview
Problem
Current SOC estimation methods in energy storage systems, relying on ampere-hour integration and open-circuit voltage methods, suffer from increasing errors over time, leading to inaccurate SOC readings and sudden jumps to 100% or 0% at the end of charging or discharging, affecting user experience.
Innovation Solution
A method and device for calibrating SOC at the tail end of charging or discharging by acquiring battery parameters, comparing them with pre-calibrated values to determine if SOC calibration conditions are met, and adjusting the SOC accordingly, using a battery voltage curve under standard operating conditions to ensure accurate calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SOC is directly calibrated to 100% when the energy storage system is fully charged or to 0% when fully discharged, then the charging and discharging control is simplified, but the SOC accuracy deteriorates due to accumulated errors from long-term operation
Solution Approach 1:
The patent applies preliminary action by performing SOC calibration at the tail end of charging or discharging before the system reaches full charge or discharge state. The calibration is triggered when the SOC estimation error exceeds a threshold, allowing the system to correct accumulated errors proactively rather than reactively, thereby maintaining SOC accuracy without compromising control simplicity
Solution Approach 2:
The patent changes the SOC parameter dynamically by adjusting it based on the relationship between charging/discharging capacity and voltage at the tail end of charge/discharge cycles. Instead of using a fixed calibration point, the system modifies the SOC value according to measured voltage and capacity parameters, improving accuracy while maintaining operational simplicity
2Device complexity
If the SOC estimation error is allowed to accumulate over long-term operation, then the estimation method remains simple, but the user experience deteriorates due to sudden SOC jumps
Solution Approach 1:
The patent implements feedback by continuously monitoring the SOC estimation error and comparing it against a predetermined threshold. When the error exceeds the threshold at the tail end of charging or discharging, the system triggers a calibration operation to correct the SOC value, thereby preventing sudden SOC jumps and improving user experience without significantly increasing system complexity
Solution Approach 2:
The patent applies partial action by performing calibration only under specific conditions (at the tail end of charging or discharging when error exceeds threshold) rather than continuously. This selective calibration approach maintains estimation method simplicity while effectively preventing user experience degradation from SOC jumps
Data Source
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AI summary
A method and a device for calibrating an SOC at tail end of charging or discharging of an energy storage system are provided. An SOC and a voltage of a battery unit are acquired in real time during charging or discharging of the battery unit. Whether the battery unit meets an SOC calibration condition is determined by comparing the SOC of the battery unit with a pre-calibrated calibration SOC at the tail end of charging/discharge and comparing the voltage of the battery unit with a calibration voltage, so that the SOC of the battery unit is timely calibrated if the SOC calibration condition is met, thereby improving accuracy of the SOC of the battery unit, avoiding a SOC jump caused by a large difference between the SOC of the battery unit and the actual SOC at the tail end of charging or discharging, and effectively improving user experience.