Battery Polarization Cancellation for Accurate SOC Calculation
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Solution Overview
Problem
The calculation accuracy of State Of Charge (SOC) in power storage devices like secondary batteries is affected by polarization, which can lead to inaccurate SOC calculations due to changes in voltage, especially in all-solid-state batteries where delamination occurs, causing non-uniform electrical resistance and easy polarization.
Innovation Solution
Implementing polarization cancellation control by applying a voltage opposite to the polarization in the battery, either through charging or discharging, to cancel out polarization effects before calculating SOC, ensuring accurate calculations by using the ECU to execute discharging or charging control based on the battery's state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If polarization cancellation control is executed by charging or discharging the battery, then SOC calculation accuracy is improved, but additional charging/discharging operations are required which increases operational complexity
Solution Approach 1:
The system executes polarization cancellation control in advance before SOC calculation by performing brief charging or discharging operations. This preliminary action eliminates polarization effects beforehand, ensuring accurate SOC measurement without being affected by voltage deviations caused by polarization.
Solution Approach 2:
The battery system uses its own charging/discharging capability to cancel polarization internally. The control device leverages the battery's inherent electrochemical reactions to generate opposing currents that neutralize polarization, eliminating the need for external intervention or additional measurement equipment.
2Measurement precision
If polarization cancellation control is executed immediately after charging or discharging, then accurate SOC calculation is achieved, but time is required for the cancellation process
Solution Approach 1:
The control device implements periodic polarization cancellation by executing brief charging or discharging cycles at specific intervals after battery operation. This periodic intervention systematically eliminates polarization buildup without requiring continuous operation, balancing accuracy with time efficiency.
Solution Approach 2:
The system dynamically adjusts charging/discharging current parameters to optimize polarization cancellation speed. By modifying current magnitude and duration based on battery state, the system achieves effective polarization elimination in minimal time while preventing excessive operational delays.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for precise SOC calculation by eliminating the influence of polarization, enabling early and accurate determination of SOC, even in batteries prone to delamination, thus improving overall calculation accuracy.
Implementation Method 1
the polarization of the power storage device is canceled by application of a voltage having a polarity opposite to that of the power storage device
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A battery system includes a battery and an ECU. The ECU executes polarization cancellation control for canceling polarization of the battery and calculation processing for calculating SOC of the battery after the polarization cancellation control. When the polarization cancellation control is executed after the battery is discharged, the polarization cancellation control is charging control for charging the battery. When the polarization cancellation control is executed after the battery is charged, the polarization cancellation control is discharging control for discharging the battery.