Battery SOC Calculator with Capacitance Saturation Detection
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Solution Overview
Problem
Continuous charging or discharging of storage batteries leads to capacitance saturation in equivalent circuits, reducing the reliability of state of charge (SOC) calculations based on open circuit voltage (OCV).
Innovation Solution
An apparatus that includes an open-circuit voltage calculator to measure close circuit voltage across an equivalent circuit of a storage battery, calculates OCV based on the measured CCV and current, and a determiner to diagnose capacitance saturation, thereby improving the reliability of SOC calculations by disregarding saturated capacitance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous charging or discharging is performed on the storage battery, then the battery can operate continuously to provide power, but the capacitance in the equivalent circuit becomes saturated which reduces the reliability of SOC calculation
Solution Approach 1:
The patent dynamically adjusts the SOC calculation method based on the charging/discharging state. When the battery is in a static state (not charging or discharging), the system uses OCV-based SOC calculation. When charging or discharging occurs, the system switches to alternative calculation methods, making the calculation approach adaptive to the current operational state to maintain reliability.
Solution Approach 2:
The patent changes the calculation parameters based on the operational state. It monitors charging/discharging current and voltage parameters to determine when capacitance saturation occurs, and adjusts the SOC calculation methodology accordingly - using OCV correlation during static periods and alternative methods during active charging/discharging periods.
2Productivity
If OCV measurement is performed during charging or discharging, then SOC can be calculated in real-time, but the measurement becomes inaccurate due to load connection
Solution Approach 1:
The system dynamically selects the measurement and calculation method based on the battery's operational state. During charging or discharging, it uses alternative calculation approaches. When the battery transitions to a static state, it switches to OCV measurement for accurate SOC determination, making the measurement strategy adaptive to current conditions.
Solution Approach 2:
The patent monitors the battery state continuously and identifies transition points between charging/discharging and static states. By detecting when the battery enters a static state (where OCV measurement is valid), the system prepares to switch to OCV-based SOC calculation, ensuring accurate measurements are taken at the appropriate时机.
3Ease of operation
If the equivalent circuit model is used to calculate CCV and derive OCV, then SOC can be estimated during loading, but the estimation reliability decreases when capacitance is saturated
Solution Approach 1:
The system implements feedback monitoring of the battery's electrical parameters (current, voltage, temperature) to detect capacitance saturation conditions. Based on this feedback, it determines whether the equivalent circuit model predictions are reliable and switches calculation methods accordingly, ensuring accurate SOC estimation under all operating conditions.
Solution Approach 2:
The patent changes the SOC calculation approach based on detected parameter conditions. When capacitance saturation is detected through monitoring of voltage, current, and temperature parameters, the system switches from equivalent circuit model-based estimation to alternative methods, adjusting the calculation parameters to match the current operational state.
Data Source
AI summary
In an apparatus, an OCV calculator measures a close circuit voltage (CCV) across an equivalent circuit of a storage battery, and calculates an open circuit voltage (OCV) across the storage battery based on the CCV, the equivalent circuit, and a current flowing through the storage battery. The equivalent circuit simulates an electrochemical behavior of the storage battery. The equivalent circuit includes the OCV as a power supply voltage and a predetermined internal impedance connected in series to the power supply voltage. The internal impedance includes a capacitance. A calculator calculates an SOC of the storage battery as a function of the OCV. A determiner determines whether the capacitance is saturated as a function of an electrical parameter associated with a charge stored in the capacitance. A diagnosing unit diagnoses whether the SOC of the storage battery is appropriate according to whether the capacitance is saturated.