Inductive Battery Diagnostics for Real-Time SoC and SoH Estimation
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Solution Overview
Problem
Existing methods for accurately estimating the electrochemical state of rechargeable batteries, such as state of charge (SoC) and state of health (SoH), are either too time-intensive or not accurate enough, particularly for online applications in electric vehicles (EV) and energy storage systems (ESS), due to issues like voltage measurement errors, temperature dependencies, and the need for prolonged resting times.
Innovation Solution
A system utilizing a planar inductive coil and current sensor to measure battery electrochemical states by compensating for losses related to battery currents, combining coil-based measurements with ampere hour counting (AHC) and open circuit voltage (OCV) measurements, and incorporating temperature compensation to improve accuracy and enable real-time estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional voltage measurement methods are used for SoC estimation, then the measurement process is simple, but the accuracy is insufficient due to voltage measurement errors and temperature dependencies
Solution Approach 1:
The patent introduces an inductive coil as an intermediary measurement device that couples magnetically with the battery internal windings. This coil-based measurement system serves as a mediator between the battery's electrochemical state and the measurement instrument, enabling indirect measurement of SoC through inductance changes without direct electrical contact, thereby improving accuracy while maintaining relative simplicity
Solution Approach 2:
The patent replaces traditional electrical voltage measurement methods with a magnetic field-based inductive measurement system. By using electromagnetic induction principles, the system substitutes direct electrical measurements (prone to errors and temperature effects) with magnetic coupling measurements, achieving higher accuracy in SoC estimation
2Measurement precision
If prolonged resting times are used for accurate voltage measurements, then measurement accuracy improves, but the time required for online estimation increases significantly
Solution Approach 1:
The patent performs preliminary calibration by establishing the relationship between inductance and SoC under known conditions before actual measurement. This pre-established correlation allows for immediate SoC estimation during operation without requiring prolonged resting periods, enabling real-time monitoring while maintaining accuracy
Solution Approach 2:
The system performs periodic inductance measurements at operational intervals rather than requiring continuous resting periods. This periodic measurement approach enables real-time tracking of SoC changes during charging and discharging cycles, eliminating the need for prolonged static resting times while maintaining measurement accuracy
3Productivity
If coil-based measurement is used for SoC estimation, then real-time estimation is enabled, but errors accumulate without periodic reset
Solution Approach 1:
The patent implements a feedback mechanism where periodic full inductance-based SoC measurements are used to correct and reset the accumulated errors in the continuous estimation process. The system continuously monitors inductance changes for real-time tracking, then periodically performs comprehensive measurements to recalibrate, creating a feedback loop that maintains long-term accuracy while preserving real-time capability
Solution Approach 2:
The system performs preliminary comprehensive inductance measurements at intervals to establish accurate baseline SoC values before resuming continuous real-time estimation. This periodic recalibration action prevents error accumulation by resetting the estimation baseline, allowing the system to maintain both real-time responsiveness and long-term accuracy
4Productivity
If AHC measurement is used for SoC tracking, then continuous monitoring is achieved, but accumulated error increases over time
Solution Approach 1:
The patent combines AHC-based continuous monitoring with periodic inductance-based calibration measurements in a feedback system. The inductance measurements serve as reference points that correct the accumulated errors in AHC integration, creating a hybrid approach where the strengths of both methods complement each other - AHC provides continuous tracking while inductance measurements periodically reset and validate the accuracy
Solution Approach 2:
The system merges two different measurement approaches - AHC (ampere-hour counting) for continuous monitoring and inductance-based measurement for periodic calibration - into a unified SoC estimation system. This combination allows the system to leverage the continuous nature of AHC while using inductance measurements to correct accumulated errors, achieving both continuous monitoring and maintained accuracy
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
The system provides accurate and efficient online estimation of battery SoC and SoH, minimizing errors and enabling reliable battery management by compensating for battery current effects and temperature variations, thus prolonging battery life and preventing malfunctions.
Implementation Method 1
Alternating current with a fixed frequency is applied to the coil to generate magnetic fields, and the magnetic fields induce losses including Eddy current loss and a loss related to battery currents
Implementation Method 2
the magnetic fields induce losses including Eddy current loss and a loss related to battery currents
Data Source
AI summary
Disclosed is a system and methods for measuring electrochemical state of rechargeable batteries such as state of charge (SoC) and state of health (SoH). In various aspects, the system may include an inductive coil attached to the battery and a battery current sensor. Alternating current with a fixed frequency is applied to the coil to generate magnetic fields, and the magnetic fields induce losses including Eddy current loss and a loss related to battery currents. The system compensates for the effect of the loss related to battery currents for battery electrochemical state estimation. In another aspect, the system uses both coil-based measurement and ampere hour counting (AHC) measurement for SoC measurement. The system conducts coil-based SoC measurement only occasionally to reset the accumulated error of AHC-based SoC measurement. In yet another aspect, the system combines coil-based measurement with other measurements.