Fiber Optic Sensor for Battery State of Charge
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Solution Overview
Problem
Existing battery technologies cannot accurately measure the state of charge in individual battery cells, which hinders early detection of cell failure and fire protection.
Innovation Solution
Incorporating a fiber-optic sensor with fiber Bragg gratings that detect mechanical expansion and temperature changes within the battery cell, allowing for precise determination of the state of charge and enabling early detection of potential failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiber-optic sensors are used to detect temperature and mechanical expansion in battery cells, then measurement precision and reliability are improved, but device complexity increases
Solution Approach 1:
The patent divides the monitoring function into separate specialized sensors: fiber-optic sensors for temperature measurement and strain gauges for mechanical expansion detection. Each sensor type is optimized for its specific measurement task, improving overall measurement precision while allowing independent selection and placement of sensor components within the battery structure.
Solution Approach 2:
The fiber-optic sensor system serves multiple functions: it measures both temperature and mechanical expansion (through Bragg grating reflections), providing comprehensive state of charge monitoring through a single integrated optical platform. This multi-functionality reduces the need for separate sensor systems while maintaining high measurement precision.
2Reliability
If multiple sensors are installed in each battery cell to detect temperature and mechanical expansion, then reliability of failure detection is improved, but manufacturing complexity increases
Solution Approach 1:
The fiber-optic sensors and strain gauges are integrated into the existing battery cell structure during manufacturing. The sensors are embedded within the battery housing or attached to the cell casing, allowing simultaneous production of battery cells and sensor integration in a single manufacturing process, thereby reducing overall complexity despite the presence of multiple sensors.
Solution Approach 2:
The patent combines temperature monitoring and mechanical expansion detection into a unified sensor system architecture where multiple measurement functions are coordinated through a common data processing and evaluation unit. This merging approach simplifies the manufacturing process by reducing the number of separate system integrations needed while maintaining reliable multi-parameter monitoring.
3Measurement precision
If mechanical expansion of battery cells is monitored to determine state of charge, then accuracy of state of charge determination is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent replaces direct mechanical measurement of battery cell expansion with optical measurement using fiber-optic Bragg gratings and strain gauges. These sensors convert mechanical expansion into optical signal changes (wavelength shifts) that can be precisely measured without physical contact, thereby improving measurement precision while reducing the difficulty of detection compared to direct mechanical measurement methods.
Solution Approach 2:
The system monitors changes in physical parameters (temperature, mechanical strain, volume expansion) that correlate with state of charge. By measuring these parameter changes through specialized sensors and correlating them to charge state through evaluation algorithms, the system achieves accurate state of charge determination while avoiding the complexity of direct chemical or electrical measurements.
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 solution provides accurate and reliable monitoring of battery cell state and current, enabling early failure detection and improved fire protection by controlling charge and discharge currents, thus enhancing battery safety and performance.
Implementation Method 1
the sensor detects a mechanical stress which is induced when the size of the battery cell or of the battery housing changes
Implementation Method 2
the sensor can be configured to additionally detect a temperature
Implementation Method 3
the battery cell is provided to convert chemical energy into electric energy
Implementation Method 4
there is also a mechanical expansion of the battery cell in accordance with the state of charge
Data Source
AI summary
The invention relates to a battery comprising a battery housing and at least one battery cell and at least one fiber optic sensor which has at least one waveguide with a core and a material surrounding said core. At least one fiber Bragg grating is introduced in the core and is mechanically coupled to the battery housing and/or to the battery cell in order to detect a change in size of the battery housing and/or of the battery cell. At least a second fiber Bragg grating is introduced in the core and is mechanically decoupled from the battery housing and the battery cell. The invention further relates to a method for the open loop or closed loop control of the charging and/or discharging of a battery, measurement values being acquired by at least one fiber optic sensor.