C-Shaped Magnetic Sensor for Iron Phosphate Battery SOC
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Solution Overview
Problem
Existing methods for determining the state-of-charge (SOC) of batteries, such as nickel metal hydride and certain lithium-ion batteries, are prone to errors due to the weak dependence of open circuit voltage on SOC, especially in regions where the voltage remains nearly constant, leading to inaccurate energy and range estimations in electric vehicles.
Innovation Solution
A magnetic sensor with a C-shaped metal core is used to measure the magnetic properties of iron phosphate lithium-ion battery cells, converting these properties into SOC measurements by generating a magnetic field and detecting the induced current, which is then converted to representative SOC values using a detection circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open circuit voltage measurement is used to determine battery SOC, then the measurement is easy to obtain, but the measurement precision deteriorates due to weak dependence of voltage on SOC in certain regions
Solution Approach 1:
The patent replaces the electrical voltage measurement system with a magnetic field-based measurement system. Instead of measuring open circuit voltage through electrical sensors and circuits, the invention uses magnetic sensors to detect changes in magnetic susceptibility of the iron phosphate material, which varies linearly with SOC. This substitution resolves the contradiction by providing accurate SOC measurement through magnetic properties rather than electrical voltage.
Solution Approach 2:
The patent changes the measurement parameter from electrical voltage to magnetic susceptibility. By measuring the magnetic susceptibility of iron phosphate, which has a linear relationship with SOC across the entire charge range, the system overcomes the flat voltage-SOC relationship. The magnetic susceptibility parameter provides continuous variation with SOC, enabling precise determination throughout the battery's operating range.
2Measurement precision
If complex models and algorithms are employed to estimate open circuit voltage under load, then voltage measurement capability is maintained, but device complexity increases
Solution Approach 1:
The patent replaces complex electrical estimation models with a direct magnetic measurement system. Instead of using algorithms to estimate voltage under load conditions, the invention directly measures magnetic susceptibility, which linearly correlates with SOC regardless of load conditions. This eliminates the need for complex computational models and algorithms while maintaining measurement capability.
3Measurement precision
If magnetic sensors are used to measure SOC based on magnetic properties of iron phosphate, then SOC determination accuracy is improved, but device complexity increases compared to voltage sensing
Solution Approach 1:
The patent extracts only the essential magnetic measurement components needed for SOC determination. The system uses a simple magnetic sensor that detects changes in magnetic susceptibility of the iron phosphate material. By focusing solely on measuring magnetic properties rather than implementing complex multi-parameter sensing systems, the invention achieves accurate SOC measurement with relatively simple device architecture.
Solution Approach 2:
The patent changes the measurement parameter to magnetic susceptibility, which provides a direct linear relationship with SOC. This parameter change simplifies the measurement system because magnetic susceptibility varies continuously and linearly with SOC, unlike voltage which has flat regions. The simplified magnetic measurement approach provides accurate SOC determination without requiring complex signal processing or multiple sensors.
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 approach provides accurate SOC determination, especially in regions where open circuit voltage is not indicative, enhancing battery management and reducing errors in energy and range estimations for electric vehicles.
Implementation Method 1
A driving coil is wrapped around one end of the magnetic core and generates a magnetic field in the core that extends across the transverse opening and through the battery cell
Implementation Method 2
A receiving coil is wrapped around an opposite end of the core that receives the magnetic field, and converts the magnetic field to a representative current
Implementation Method 3
it is the magnetic properties of the iron phosphate that changes as the cell SOC changes in a linear manner. Specifically, as the SOC of the battery cell increases, the magnetic susceptibility of the iron phosphate decreases
Data Source
AI summary
A magnetic sensor for measuring the magnetic properties of a battery cell, and converting the magnetic properties to a battery cell SOC. The magnetic sensor includes a magnetic core formed of laminated high permeability plates provided in a C-shape. An extended portion of the battery cell extends through a transverse opening in the core so that it is positioned within the core. A driving coil is wrapped around one end of the magnetic core and generates a magnetic field in the core that extends across the transverse opening and through the battery cell. A receiving coil is wrapped around an opposite end of the core that receives the magnetic field, and converts the magnetic field to a representative current. A detection circuit converts the receiving coil current to the battery cell SOC.