Lithium-Ion SOC Diagnosis Using Lebesgue Sampling and ECM Updates

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Solution Overview

Problem

Traditional state-of-charge (SOC) estimation and prediction methods for lithium-ion batteries face challenges due to high computation costs in electrochemical models and inaccuracies in equivalent circuit models, and the traditional open circuit voltage (OCV) acquisition method is time-consuming and inefficient.

Innovation Solution

The integration of Lebesgue sampling (LS) with the equivalent circuit model (ECM) for lithium-ion batteries, considering the nonlinearity of terminal voltage, allows for parameter updates and reduces computation costs while enabling accurate SOC diagnostics and prognostics by fitting OCV points after sufficient rest periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrochemical model is used for SOC estimation, then accuracy is improved, but computation cost increases

Engineering Contradiction:
ImproveSOC estimation accuracyVSAvoidcomputation cost
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the SOC estimation process into two distinct phases: an offline training phase where the electrochemical model is used to generate accurate training data, and an online estimation phase where a simplified neural network model performs real-time SOC estimation. This segmentation allows the computationally intensive electrochemical model to be used only when necessary for training, while the lightweight neural network handles continuous online estimation with minimal computation cost.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If traditional OCV acquisition method is used, then OCV data is obtained, but time consumption increases

Engineering Contradiction:
ImproveOCV measurement accuracyVSAvoidtime cost
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing extensive OCV measurements and data collection during the offline training phase before the battery is actually deployed for use. During this preliminary stage, the battery is discharged at various rates and allowed to rest to establish accurate OCV-SOC relationships. This pre-acquired knowledge is then stored in the neural network model, eliminating the need for time-consuming OCV measurements during online operation.

Inventive Principle:
Principle #10Preliminary action

3Use of energy by moving object

If ECM with fixed parameters is used, then computation cost is reduced, but simulation accuracy deteriorates

Engineering Contradiction:
Improvecomputation costVSAvoidbattery behavior simulation accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent transforms the static fixed-parameter ECM into a dynamic adaptive model by integrating a neural network that continuously updates the ECM parameters based on real-time terminal voltage measurements. The neural network learns the nonlinear relationships between SOC, SOH, and ECM parameters during offline training, enabling the parameters to adapt dynamically during online operation. This dynamic approach maintains high simulation accuracy while keeping the computational burden manageable through efficient neural network inference.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS12560653B2Lebesgue sampling-based lithium-ion battery state-of-charge diagnosis and prognosis
Publication Date: 2026.02.24 UNIVERSITY OF SOUTH CAROLINA
  • US12560653B2 patent drawing
  • US12560653B2 patent drawing
  • US12560653B2 patent drawing

AI summary

Method provides accurate state-of-health (SOH) diagnostics and prognostics during the whole-life-service of a lithium-ion battery by considering the effects of state-of-charge (SOC) and SOH on certain parameters (such as consideration of nonlinearity of the terminal voltage) during the process of SOC diagnostics and prognostics. The method integrates Lebesgue sampling and equivalent circuit model (ECM) analysis, which greatly decreases computation cost and uncertainty accumulation to provide efficient acquisition of open circuit voltage (OCV) determinations for the ECM process. The OCV curve of the battery was obtained during Hybrid Pulse Power Characterization testing by fitting a series of selected OCV points after enough rest of the subject battery. Identified parameters of ECM are updated according to terminal voltage measurement to enable accurate SOC estimation and prediction during the period from full charge to full discharge of the battery. Parameter identification is re-conducted and an initial condition for SOC estimation is updated according to SOH to enable accurate SOC estimation during the whole-life-service of battery.