KR20250095035A - Complex physical quantitity measuring device using optical fiber sensor for lithium-ion battery status monitoring - Google Patents

Abstract

A complex physical quantity measuring device using an optical fiber sensor for lithium-ion battery condition analysis includes: a Bragg grating (FBG) sensor attached to the outside of or built into the inside of a lithium-ion battery cell or a distributed optical fiber sensor in which a measurement optical fiber is formed in a loop shape; and a complex physical quantity measuring unit which provides an optical wave having a preset frequency to one end of the Bragg grating sensor or both ends of the distributed optical fiber sensor and measures the temperature and strain of the lithium-ion battery cell based on the reflected or scattered optical wave. Accordingly, a simple optical fiber sensor having a small volume, chemical resistance, and a structure that is not affected by electromagnetic wave interference can be used for lithium-ion battery condition analysis.

Description

{COMPLEX PHYSICAL QUANTITITY MEASURING DEVICE USING OPTICAL FIBER SENSOR FOR LITHIUM-ION BATTERY STATUS MONITORING}

The present invention relates to a complex physical quantity measuring device using an optical fiber sensor for lithium ion battery state analysis, and more specifically, to a technology for monitoring internal information of a battery cell or the temperature and strain of a module composed of a plurality of cells.

Lithium-ion batteries are used in a wide range of fields, including portable electronic devices, electric vehicles, satellites, energy storage systems, medical devices, and unmanned aerial vehicles, due to their high energy density, light weight, long life, fast charging speed, compatibility with existing electrical infrastructure, and environmental friendliness.

Recently, as the energy density of batteries increases, the safety of batteries has become an important issue. Excessive heat generated during rapid charging and discharging can permanently degrade the performance of cells, and internal short circuits and mechanical shocks can lead to thermal runaway, damaging not only adjacent cells in the battery pack but also the entire system, which can lead to fatal safety issues. Therefore, it is necessary to ensure battery operation that maintains safety and high efficiency for a long period of time through continuous battery condition monitoring.

However, the existing battery management system (BMS) that monitors and manages (balances) and controls the battery status has a complex structure between the slave attached to each cell and the master controller in charge of control. In particular, existing sensors attached to the surface to prevent cell performance degradation have the problem of having difficulty detecting rapid temperature changes inside the cell, such as thermal runaway.

Therefore, it is necessary to monitor the internal information of a battery cell or the temperature and pressure distribution of a module composed of multiple cells by utilizing an optical fiber-based sensor that is small enough to not cause performance degradation when integrated with a battery cell and has the characteristics of chemical resistance and immunity to electromagnetic interference.

Accordingly, the technical problem of the present invention is conceived from this point, and the purpose of the present invention is to provide a complex physical quantity measuring device using an optical fiber sensor for lithium ion battery state analysis.

According to one embodiment of the present invention for realizing the purpose described above, a complex physical quantity measuring device using an optical fiber sensor for lithium-ion battery state analysis includes a Bragg grating (FBG) sensor attached to the outside of a lithium-ion battery cell or built into the inside thereof, or a distributed optical fiber sensor in which a measuring optical fiber is formed in a loop shape; and a complex physical quantity measuring unit which provides an optical wave having a preset frequency to one end of the Bragg grating sensor or both ends of the distributed optical fiber sensor, and measures temperature and strain of the lithium-ion battery cell based on the reflected or scattered optical wave.

In an embodiment of the present invention, one end of the Bragg grating sensor and both ends of the distributed optical fiber sensor can be separated from the lithium ion battery cell to opposite ends where the electrodes are formed.

In an embodiment of the present invention, the Bragg grating sensor may have a diameter of 20 μm or more and 80 μm or less.

In an embodiment of the present invention, the Bragg grating sensor may use a tapered optical fiber that has been tensioned to reduce its diameter.

In an embodiment of the present invention, the Bragg grating sensor may use an optical fiber whose diameter has been reduced by etching the cladding.

In an embodiment of the present invention, when a Bragg grating sensor is used, the composite physical quantity measuring unit may include a Fabry-Perot resonator and one or more interrogators.

In an embodiment of the present invention, the distributed fiber optic sensor may include two measurement fibers having different Brillouin frequency coefficients for temperature and strain.

In an embodiment of the present invention, the distributed optical fiber sensor may include a Large Effective Area Fiber (LEAF) having multiple Brillouin spectral peaks.

In an embodiment of the present invention, a distributed optical fiber sensor may include a Double Brillouin Peak Fiber (DBPF) having two Brillouin spectral peaks.

In an embodiment of the present invention, a distributed optical fiber sensor may include a multi-core optical fiber having a plurality of cores.

In an embodiment of the present invention, when a distributed optical fiber sensor is used, the complex physical quantity measurement unit may use optical frequency domain reflectometry (OFDR) or Brillouin optical correlation domain analysis (BOCDA).

In an embodiment of the present invention, a composite physical quantity measuring device using an optical fiber sensor for lithium-ion battery state analysis can be applied to a battery management system (BMS).

According to a composite physical quantity measuring device using an optical fiber sensor for lithium-ion battery condition analysis, a Bragg grating (FBG) sensor or a distributed optical fiber sensor can be attached or built into a battery module to measure physical quantities such as temperature and strain through signal processing of a measuring unit. According to the present invention, the internal condition of a battery can be constantly monitored using an optical fiber sensor having a small volume, chemical resistance, and a simple structure that is not affected by interference from electromagnetic waves. Accordingly, it is possible to detect thermal runaway of the battery before the battery runs out and block the operation of the battery cell, thereby preventing damage to the battery.

FIG. 1 is an exemplary drawing of a Bragg grating sensor for lithium ion battery state analysis according to one embodiment of the present invention.
Figure 2 is a drawing for explaining a tapered optical fiber among the Bragg grating sensors of Figure 1.
Figure 3 is a temperature change curve and a Bragg wavelength change curve when using the Bragg grating sensor of Figure 1.
FIG. 4 is a drawing for explaining an embedded optical fiber sensor according to one embodiment of the present invention.
FIG. 5 is an exemplary drawing of a distributed optical fiber sensor for lithium ion battery condition analysis according to one embodiment of the present invention.
FIG. 6 is an exemplary drawing of a distributed optical fiber sensor for lithium ion battery condition analysis according to one embodiment of the present invention.
FIG. 7 is an exemplary diagram of a case where optical frequency domain analysis (OFDR) is used in a complex physical quantity measuring device according to one embodiment of the present invention.
FIG. 8 is an exemplary diagram of a case where Brillouin optical correlation analysis (BOCDA) is used in a complex physical quantity measuring device according to one embodiment of the present invention.
FIG. 9 is a block diagram of a composite physical quantity measuring device using an optical fiber sensor for lithium ion battery state analysis according to one embodiment of the present invention.

The detailed description of the present invention set forth below refers to the accompanying drawings which illustrate specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention, while different from one another, are not necessarily mutually exclusive. For example, specific shapes, structures, and features described herein may be implemented in other embodiments without departing from the spirit and scope of the invention. It should also be understood that the positions or arrangements of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the following detailed description is not intended to be limiting, and the scope of the invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if any. Like reference numerals in the drawings designate the same or similar functionality throughout the several aspects.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

A composite physical quantity measuring device (50, see FIG. 9) using an optical fiber sensor for lithium ion battery condition analysis according to the present invention can constantly monitor the internal condition of a battery by including an optical fiber sensor (700, see FIG. 9) and a composite physical quantity measuring unit (800, see FIG. 9).

In the present invention, the optical fiber sensor (700) may be configured as a Bragg grating (FBG) sensor or a distributed optical fiber sensor. The Bragg grating sensor or the distributed optical fiber sensor may be attached to the outside of a lithium ion battery cell or built into the inside.

The complex physical quantity measuring unit (800) provides light waves with a preset frequency to one or both ends of the optical fiber sensor (700) and measures the temperature and strain of a lithium ion battery cell based on the light waves reflected or scattered by the optical fiber sensor.

FIG. 1 is an exemplary drawing of a Bragg grating sensor for lithium ion battery state analysis according to one embodiment of the present invention.

Referring to FIG. 1, a Bragg grating sensor (100) is attached to the outside of a lithium ion battery cell (10, hereinafter referred to as a battery cell). For example, the Bragg grating sensor (100) may be attached to the battery cell (10) using an adhesive (17), and one end of the Bragg grating sensor (100) may be detached to the opposite side where the positive and negative electrodes (11, 12) of the battery cell (10) are formed.

A Bragg grating sensor (100) has the characteristic that light of a narrow range of specific wavelength bands (Bragg wavelengths) is reflected by a refractive index grating periodically generated in an optical fiber core, and the remaining wavelength bands are transmitted.

Since the Bragg wavelength is determined by the refractive index of the optical fiber core and the spacing of the Bragg wavelength, a Bragg grating sensor (100) having a selective Bragg wavelength can be manufactured by adjusting the spacing of the Bragg grating during manufacturing. In the Bragg grating sensor (100), the Bragg wavelength reflected changes as the spacing of the grating changes when the optical fiber is stretched and contracted, and a change in temperature affects the Bragg wavelength due to the temperature dependence of the refractive index and thermal expansion and contraction.

The Bragg grating sensor (100) consists of a core with a diameter of about 10 μm and a cladding with a diameter of about 125 μm. Due to its small form factor, it has little heat influence and its capacity and safety have been verified even after hundreds of charge-discharge cycles, making it suitable as an embedded sensor.

The Bragg grating sensor (100) can simultaneously measure temperature and strain, thereby enabling prediction of battery malfunction. In addition, by connecting a plurality of Bragg grating sensors (100) having different Bragg wavelengths to an interrogator, it is also possible to monitor temperature and pressure distribution for each cell within the battery cell (10).

Additionally, the Bragg grating sensor (100) can maintain excellent stability in the highly corrosive internal environment of a battery cell (10) due to the chemical inertness of the components.

The Bragg grating sensor (100) may be mounted inside the battery cell (10) or attached to the outside of the battery cell (10). In particular, when mounted inside the battery cell (10), a low-diameter Bragg grating sensor (100) based on tapered optical fiber or cladding etching may be used.

In this case, it is possible to prevent an electrolyte leak phenomenon that may occur during the battery cell (10) sealing process, and minimize a decrease in electrolyte capacity. In addition, monitoring can be performed at a high response speed due to rapid heat transfer from the battery cell (10) to the optical fiber core.

The diameter including the core and cladding of the tapered optical fiber or cladding etching-based Bragg grating sensor (100) may be 20 μm or more and 80 μm or less. A tapered optical fiber refers to an optical fiber that has a diameter that is reduced from the original optical fiber over a certain length.

Figure 2 is a drawing for explaining a tapered optical fiber among the Bragg grating sensors of Figure 1.

Referring to Fig. 2, an optical fiber is tensioned to create a tapered optical fiber (110). In the tapered optical fiber (110), the core (111) and the cladding (112) surrounding the core (111) are tensioned, so that the diameter of the middle portion is changed.

The portion where the diameter of the core (111) and cladding (112) is changed becomes a tapered region, and the middle portion (C) where the reduced diameter is constant, excluding the regions (A, B) where the diameter is reduced or increased, is cut out and used.

Afterwards, a Bragg grating can be formed and used as a Bragg grating sensor (100) of the present invention.

Meanwhile, a Bragg grating sensor (100) based on cladding etching can be used by placing an optical fiber on which a Bragg grating is formed into an etching solution (e.g., diluted hydrogen fluoride aqueous solution) and etching the cladding until the desired diameter is achieved.

Although the embodiment of FIG. 1 illustrates one Bragg grating sensor (100), the Bragg grating sensors (100) may include multiple ones. The multiple Bragg grating sensors (100) may each be attached to or built into different battery cells (10), and the multiple Bragg grating sensors (100) may also be attached to a battery module or battery pack composed of multiple battery cells (10).

When a Bragg grating sensor is used as an optical fiber sensor (700), the composite physical quantity measuring unit (800) may be, for example, an interrogator or may include an interrogator.

When the complex physical quantity measuring unit (800) includes an interrogator, it is possible to measure and analyze Bragg wavelength changes for a plurality of Bragg grating sensors (100) whose Bragg wavelength ranges do not overlap in one channel. In addition, since a plurality of channels can be installed in one interrogator, it is also possible to simultaneously measure and analyze physical characteristics for battery cells (10) constituting a battery module and pack.

The complex physical quantity measuring unit (800) can estimate the state of the battery through a change curve of temperature or pressure according to time during charging and discharging of the battery cell (10).

Figure 3 shows a temperature change curve obtained by attaching a temperature and Bragg grating sensor (100) to the surface of a battery cell (10) during a 1C charge, rest, and 1C discharge cycle using a commercially available lithium polymer battery.

Fig. 3a shows the voltage of the cell (dotted line) and the temperature change (solid line) measured by a conventional thermometer during a charge/discharge cycle. Fig. 3b shows the Bragg wavelength shift measured by a Bragg grating sensor (100) having a Bragg wavelength of about 1546.22 nm at room temperature (about 23.5° C.).

Referring to FIGS. 3a and 3b, when measuring using a Bragg grating sensor (100), not only is the temperature precision high, but strain due to volume change of the battery cell (10) during the charging and discharging process is simultaneously measured, so it can be confirmed that precise physical quantity observation is possible.

In another embodiment, a hybrid sensor combining a Bragg grating sensor (100) and a Fabry-Perot (hereinafter referred to as FP) resonator can be configured to measure the physical quantities of temperature and strain separately.

In this case, the strain value inside the battery cell (10) due to thermal expansion can be extracted by using the difference between the strain and temperature sensitivity of the Bragg wavelength of the Bragg grating sensor (100) and the strain and temperature sensitivity of the FP resonator.

Meanwhile, when the Bragg grating sensor (100) is formed as an embedded type, a sealing failure may occur during the process of sealing the battery cell (10) at risk of electrolyte leakage. This may lead to electrolyte leakage or cause a decrease in cell performance or failure due to moisture or temperature changes. To prevent this, a heat seal film used when sealing the tab of the battery cell (10) may be utilized to prevent void generation.

FIG. 4 is a drawing for explaining an embedded optical fiber sensor according to one embodiment of the present invention.

Referring to FIG. 4, a cross-sectional view of a battery cell (10) is shown, in which a positive electrode and a negative electrode (11, 12) are formed on both sides of a separator (15) in an electrolyte (13), and the optical fiber sensor (200) of the present invention can be formed between the separator (15) and the positive electrode or negative electrode (11, 12).

The optical fiber sensor (200) formed inside the battery cell (10) may be not only a Bragg grating sensor (100) but also a distributed optical fiber sensor (300) described below.

As described above, the method of attaching a Bragg grating sensor (100) to the outside of a battery cell (10) or inserting it inside can measure temperature and strain with high precision, and can configure a battery management system (BMS) relatively easily using a commercialized interrogator.

However, since the number of channels of the interrogator is limited and the Bragg grating sensors (100) located in one channel must be selected so that the Bragg wavelength bands of the Bragg grating sensors (100) do not overlap, it may be difficult to monitor all cells of a large battery pack.

In addition, since the Bragg grating sensor (100) is a point sensor that acts as a sensor only in the part where the Bragg grating is engraved, it is possible to obtain physical quantity information about the positive electrode, negative electrode, or center of the battery cell (10) where a rapid temperature rise occurs, but it may be difficult to measure the physical quantity distribution over the entire inside of the battery cell (10).

Therefore, the present invention can use a distributed optical fiber sensor capable of measuring the distribution of physical quantities for all areas of an optical fiber attached to the outside of a battery cell (10) or inserted inside a measuring optical fiber made of a single-mode optical fiber for communication or a special optical fiber.

FIG. 5 is an exemplary drawing of a distributed optical fiber sensor for lithium ion battery condition analysis according to one embodiment of the present invention.

FIG. 5 illustrates an example in which a measuring optical fiber (300) is attached in a loop shape to the outside of a battery cell (10), but the distributed optical fiber sensor (300) of the present invention can be formed as a built-in type as in FIG. 4.

Additionally, both ends of the measuring optical fiber (300) can be separated to opposite sides where the positive and negative electrodes (11, 12) of the battery cell (10) are formed.

The measurement optical fiber (300) can measure temperature and strain by distinguishing them using a special optical fiber. Since the Brillouin scattering frequency responds to both temperature and strain, they cannot be distinguished.

Long-term performance degradation of the battery cell (10) or volume change under abuse conditions causes a change in strain. Since this permanently deformed strain can be an indicator for estimating battery performance, separation of temperature and strain is necessary in order to develop an optical fiber sensor with built-in battery.

Figure 6 is a diagram of one embodiment using two optical fiber strands with different physical quantity coefficients.

Typically, a single optical fiber is used to determine the Brillouin frequency coefficient due to temperature changes. and Brillouin frequency coefficient due to strain can be obtained individually, but cannot be distinguished by measuring the mixed physical quantities.

Therefore, we have different Brillouin frequency coefficients depending on temperature and strain, i.e. ( ) and a first optical fiber (610) having a coefficient of ( ) can be simultaneously inserted into the second optical fiber (630) having a coefficient of , thereby enabling the temperature and strain to be distinguished through matrix analysis.

Because the location where the measurement point is generated can be specified due to the nature of the Brillouin optical correlation region analysis method, the physical quantity coefficients measured from each optical fiber sensor can be analyzed.

In another embodiment, the distributed fiber optic sensor (300) may include a measurement fiber (400) comprised of a Large Effective Area Fiber (LEAF) having multiple Brillouin spectral peaks.

LEAF is an optical fiber developed for long-distance signal transmission, and multiple Brillouin peaks are generated due to multiple acoustic modes. Each peak has a different frequency shift coefficient due to temperature and strain, and the half-width of certain peaks is fixed depending on the change in physical quantity, while the half-width of other peaks can be dependent on the change in physical quantity, so it can be used as a battery-integrated sensor to separate physical quantities.

In another embodiment, the distributed fiber optic sensor (300) may include a measurement fiber (400) comprised of a Double Brillouin Peak Fiber (DBPF) having two Brillouin spectral peaks.

DBPF is an optical fiber that generates two acoustic modes that interact with the existing optical mode. When collecting a Brillouin gain spectrum using DBPF, two Brillouin peaks with a frequency difference of several hundred MHz can be obtained.

The two peaks have different temperature and strain coefficients because they interact with different acoustic modes and optical modes, which can be used to separate physical quantities using matrix analysis in a single special optical fiber.

In another embodiment, the distributed optical fiber sensor (300) may include a measurement optical fiber (400) composed of a multi-core optical fiber. A multi-core optical fiber is an optical fiber having multiple cores within one optical fiber. It is physically impossible to manufacture cores having exactly the same number of cores. Therefore, since the Brillouin scattering frequency and the temperature and strain-induced shift coefficients occurring in each core are different, it is possible to separate physical quantities by matrix analysis.

In the present invention, when the optical fiber sensor is configured as a distributed optical fiber sensor, the complex physical quantity measuring unit (800) can use optical frequency domain reflectometry (OFDR) or Brillouin optical correlation domain analysis (BOCDA).

FIG. 7 is an exemplary diagram of a case where optical frequency domain analysis (OFDR) is used in a complex physical quantity measuring device according to one embodiment of the present invention.

The OFDR system uses a frequency-swept laser with a configuration as shown in Fig. 7(a). In addition, as shown in Fig. 7(b), it acquires and then signals a beat signal generated from Rayleigh scattered light generated from a reference optical fiber and a measurement optical fiber (400). By utilizing the fact that the time information of the Rayleigh scattered light changes when the temperature or strain around the measurement optical fiber (400) changes, the change in the beat signal is tracked.

The OFDR system is a system capable of implementing a spatial resolution of several centimeters to several millimeters, and can measure the physical quantities of optical fibers located inside a cell with a relatively simple configuration compared to other distributed optical fiber sensors.

FIG. 8 is an exemplary diagram of a case where Brillouin optical correlation analysis (BOCDA) is used in a complex physical quantity measuring device according to one embodiment of the present invention.

The BOCDA system is a system that uses two light sources with a difference in Brillouin frequency as a pump and a probe, respectively, and injects them from opposite directions into a battery pack (30) to measure the gain due to Brillouin scattering inside an optical fiber.

The BOCDA system uses the principle that the pulse waves of the pump and probe light modulated in the form of sinusoids generate points (sensing points) at which the frequency difference is constant for every half wavelength of the sine wave. As the frequency of the sine wave changes, the location of the sensing point moves as a distributed optical fiber sensor (500). Like the OFDR system, it is possible to implement a spatial resolution of several centimeters to millimeters, and by re-implementing the Brillouin gain spectrum, it is possible to measure physical quantities such as temperature and strain with high accuracy.

FIG. 9 is a block diagram of a composite physical quantity measuring device using an optical fiber sensor for lithium ion battery state analysis according to one embodiment of the present invention.

Referring to Fig. 9, a composite physical quantity measuring device (50) including an optical fiber sensor (700) of the present invention and a composite physical quantity measuring unit (800) is applied to a battery management system (BMS) (1). The optical fiber sensor (700) of the present invention can be integrated with a BMS with a simple structure.

The thermal runaway phenomenon of a secondary battery is a phenomenon in which the temperature of the cell rapidly increases due to a short circuit between the positive and negative electrodes caused by mechanical defects, overcharge, overdischarge, or the separator melting due to excessive heat energy.

If one cell in a battery pack experiences thermal runaway, the temperature of the physically adjacent cells will rise, causing a chain reaction of thermal runaway reactions. Thermal runaway causes the temperature to rapidly rise to hundreds of degrees Celsius, a temperature at which the battery cannot function properly, and additionally releases harmful gases, causing financial and human damage, so the reaction of the problematic cell must be blocked at the beginning.

Since the internal temperature of the cell rises rapidly compared to the temperature measured outside the cell when a thermal runaway phenomenon occurs, it is necessary to insert a sensor inside the cell for early diagnosis.

Therefore, the introduction of a distributed optical fiber sensor according to the present invention enables diagnosis after observation of a thermal runaway precursor phenomenon that may occur at a non-specific location within a cell by constant monitoring of all cells in a battery pack and measurement of the distribution of cell physical quantities.

As the energy density of lithium-ion batteries, which are being applied in various fields, increases, there is increasing interest in battery performance degradation and safety. In rapid charging and discharging situations, the temperature rise of the battery can lead to thermal runaway phenomenon that not only reduces performance but also damages the entire system.

Thermal runaway of batteries not only causes physical hazards such as fire or explosion, but also chemical hazards such as the release of toxic gases. In order to diagnose the above phenomenon early, a sensor system that can be inserted into the battery is required, and FBG or distributed optical fiber sensors can be embedded in the cell with a small volume of about 100 μm without affecting the performance of the cell.

In addition, unlike existing BMS, it does not require multiple controllers, so it can be operated space- and power-efficiently. Since it can predict battery aging that may occur during driving and rapid charging/discharging of electric vehicles with a single system, and estimate the location and occurrence time of cells showing signs of thermal runaway, it can prevent fires and explosions caused by thermal runaway in advance, so the optical fiber sensor can be used as an efficient and powerful BMS along with existing BMS.

Although the present invention has been described above with reference to embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

The present invention can extend the application of optical fiber sensors from the cell level to the module and pack level. In automotive and grid-scale battery systems, large battery cells form modules and packs, so monitoring of various parameters such as temperature and negative voltage is also possible in these systems. Therefore, advanced optical fiber sensing such as the present invention can be applied to BMS to improve battery safety, reliability, performance, and lifespan.

100: Bragg grating sensor
300, 610, 630, 400, 500: Measurement Fiber Optic
200, 700: Fiber Optic Sensor
800: Complex physical quantity measurement unit
50: Complex physical quantity measuring device
1: BMS
10: Battery Cell
11, 12: positive, negative
17: Adhesive
110: Tapered optical fiber
111: Core
112: Cladding
13: Electrolyte
15: Membrane
810: OFDR System
830: BOCDA System
30: Battery Pack

Claims (12)

A distributed optical fiber sensor in which a Bragg grating (FBG) sensor or a measuring optical fiber is formed in a loop shape and is attached to the outside or built into the inside of a lithium-ion battery cell; and
A composite physical quantity measuring device using an optical fiber sensor for lithium-ion battery state analysis, comprising: a composite physical quantity measuring unit for measuring temperature and strain of a lithium-ion battery cell based on reflected or scattered optical waves by providing optical waves having a preset frequency to one end of a Bragg grating sensor or both ends of a distributed optical fiber sensor;
In the first paragraph,
A composite physical quantity measuring device using an optical fiber sensor for lithium-ion battery condition analysis, wherein one end of a Bragg grating sensor and both ends of a distributed optical fiber sensor are separated from each other to opposite ends where electrodes are formed in a lithium-ion battery cell.
In the first paragraph,
A Bragg grating sensor is a composite physical quantity measuring device that uses an optical fiber sensor for lithium-ion battery state analysis, having a diameter of 20 μm or more and 80 μm or less.
In the third paragraph,
A Bragg grating sensor is a composite physical quantity measuring device that uses an optical fiber sensor for lithium-ion battery condition analysis, using a tapered optical fiber that has been stretched and reduced in diameter.
In the third paragraph,
A Bragg grating sensor is a composite physical quantity measurement device that uses an optical fiber sensor for lithium-ion battery condition analysis, using an optical fiber whose diameter has been reduced by etching the cladding.
In the first paragraph,
When using a Bragg grating sensor,
A complex physical quantity measuring device using an optical fiber sensor for lithium-ion battery state analysis, wherein the complex physical quantity measuring unit includes a Fabry-Perot resonator and one or more interrogators.
In the first paragraph,
A distributed optical fiber sensor is a composite physical quantity measuring device using an optical fiber sensor for lithium-ion battery state analysis, comprising two measuring optical fibers having different Brillouin frequency coefficients for temperature and strain.
In the first paragraph,
A distributed optical fiber sensor is a composite physical quantity measuring device that uses an optical fiber sensor for lithium-ion battery state analysis, including a LEAF (Large Effective Area Fiber) having multiple Brillouin spectral peaks.
In the first paragraph,
A distributed optical fiber sensor is a composite physical quantity measuring device that uses an optical fiber sensor for lithium-ion battery state analysis, including a DBPF (Double Brillouin Peak Fiber) having two Brillouin spectral peaks.
In the first paragraph,
A distributed optical fiber sensor is a composite physical quantity measuring device that uses an optical fiber sensor for lithium-ion battery state analysis, including a multi-core optical fiber having a plurality of cores.
In the first paragraph,
When using distributed fiber optic sensors,
The complex physical quantity measurement unit is a complex physical quantity measurement device that uses an optical fiber sensor for lithium-ion battery state analysis using optical frequency domain reflectometry (OFDR) or Brillouin optical correlation domain analysis (BOCDA).
In the first paragraph,
A complex physical quantity measuring device that uses an optical fiber sensor to analyze the state of a lithium-ion battery, applied to a battery management system (BMS).