Method for detecting internal core temperature of power battery
Technical Field
The invention is mainly applied to the field of power battery manufacturing and application. The technical field is particularly a detection method for the internal core temperature of a power battery.
Background
By combining the electric automobile 2025 planning and the guidance suggestion of energy storage industry development, various energy storage products such as power batteries enter a high-speed development period, the safety performance of the power batteries becomes one of important restriction factors for power battery application along with the continuous improvement of the energy density of the power batteries, and the internal core temperature data of the power batteries can be used as important prejudgment data of the safety performance of the power batteries in the charging and discharging processes; in order to improve the safety performance of the power battery and prevent thermal runaway and internal short circuit of the power battery, it is necessary to measure internal core data of the power battery in real time during the application process.
The existing power battery temperature measurement has many defects as follows:
1. most power batteries are not designed for measuring the internal core temperature, only the surface temperature of the power battery can be tested, the highest temperature of the internal core is difficult to accurately obtain, the temperature change of the internal core cannot be measured in time, and the potential safety hazard cannot be pre-warned in time;
2. in the production and winding process of some power batteries, a temperature measuring probe is fixed at a preset position in the battery and is connected to a test system through a lead, and the mode has the influences of influencing the winding shape of the power battery, causing the influences of deformation in a certain area, uneven current distribution, large polarization and the like, and simultaneously having the risk of internal short circuit;
3. the core temperature measuring mode in the power battery mostly measures the temperature through a plurality of temperature probe sampling points, the temperature measurement has the problems of narrow radiation range or excessive sampling points which influence winding and the like, and the measurement of the core temperature is seriously restricted;
4. the core temperature in the power battery adopts a temperature probe measurement mode, a lead is required to lead out an electrical signal measured by the temperature probe, and the lead has the possibility of corrosion and damage, so that the electrical signal of the probe affects the safety of the battery;
5. the core temperature in the power battery adopts a temperature probe measuring mode, the single-point temperature in the battery can be measured at every time, the temperature distribution data in the battery can not be acquired in real time, the accurate maximum core temperature in the battery can not be acquired in real time, and the temperature in the battery can not be protected in time when abnormal, so that the use safety of the battery is influenced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for detecting the internal core temperature of a power battery, which can effectively solve the problems in the background art.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a detection method of the core temperature in a power battery comprises a terminal PC, a wavelength demodulator, a battery with a built-in fiber grating sensor array, an optical fiber line and a communication line, wherein the communication line is used for receiving wavelength coding temperature sensing data of different test points in the battery, which are transmitted by the wavelength demodulator, and calculating and displaying the distribution condition of the temperature data in the battery on terminal PC acquisition software;
the wavelength demodulator comprises a broadband light source emitter, a 3dB coupler, an F-P filter, a photoelectric detection signal amplifier and a data acquisition card, wherein an internal broadband light source emitter emits a light source to a battery with a built-in fiber grating sensor array through a 3dB coupler through an optical fiber, fiber gratings with different central wavelengths (lambda b1, lambda b2, … and lambda bn) correspond to temperature measurement points in the battery, the temperature changes of the points to be measured are respectively sensed, reflected light carrying temperature information is transmitted to the wavelength demodulator through the optical fiber, and the wavelength demodulator converts temperature sensing signals with wavelength codes into digital signals and is connected with a terminal PC through the internal data acquisition card;
the battery with the built-in fiber grating sensor array comprises a battery case and a battery upper cover clamped above the battery case, wherein a plurality of circles of core packages are wound in the battery case, a plurality of fiber grating sensors are arrayed on the core packages, each fiber grating sensor consists of an optical fiber line and a plurality of fiber gratings with different wavelengths which are connected in series on the optical fiber line, the internal temperature of the battery is measured by adopting the fiber gratings, the wavelength movement of each fiber grating in each temperature test point in the battery within a temperature measurement range cannot be superposed with each other by utilizing wavelength division multiplexing and time division multiplexing, and the accurate measurement of the internal temperature data distribution condition of the battery is realized by pre-embedding the designed fiber grating sensor array in the battery.
By way of further illustration, the terminal PC is connected to the wavelength demodulator through a communication line, and the battery of the built-in fiber grating sensor array is connected to the wavelength regulator through a fiber optic line.
By way of further illustration, the fiber optic line is responsible for transmitting the emitted light from the wavelength demodulator to the battery of the built-in fiber grating sensor array and transmitting the reflected light carrying the temperature information from the battery of the built-in fiber grating sensor array to the wavelength demodulator, and the communication line is responsible for transmitting the wavelength temperature encoded digital signal demodulated by the wavelength demodulator to the terminal PC.
As a further elaboration, the broadband light source emitter, the 3dB coupler, the F-P filter, the photoelectric detection signal amplifier and the data acquisition card are sequentially connected.
Compared with the prior art, the invention has the beneficial effects that:
the embodiment provides a method for detecting the internal core temperature of a power battery,
1. the method has the advantages that the reliable measurement of the core temperature inside the power battery is realized;
2. the problems that the core temperature sampling method in the power battery affects the winding of the battery core, and the deformation and the uneven current distribution of the power battery are reduced due to the fact that the fiber bragg grating has the physical characteristics of small size, flexibility, easiness in winding and the like and is thin relative to the winding of the battery are solved;
3. the complexity of a temperature measurement system is reduced, the fiber bragg grating array can be laid in a winding layer in the battery according to a designed shape, the measurement area of the core temperature in the power battery is increased, and the maximum value of the core in the power battery is accurately measured;
4. the problem that the battery safety is influenced by a temperature probe measuring mode is solved, the adopted fiber bragg grating belongs to a passive device, has the characteristics of corrosion resistance, electromagnetic interference resistance and the like, core temperature distribution data in the battery are accurately measured through the change of the reflection wavelength of an optical signal in the fiber bragg grating, the influence of an electric signal on the battery is not needed to be worried about, and the influence on the electrochemical reaction of the power battery is synchronously reduced;
5. the fiber bragg grating is adopted to measure the internal temperature of the battery, real-time acquisition can be realized, the acquisition time can be less than 10MS, and the rapid detection of the temperature change of the power battery is realized; and the temperature inside the battery can be measured in a networking way by utilizing wavelength division multiplexing and time division multiplexing, and the temperature distribution conditions of different measuring points inside the battery can be obtained.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic diagram of the internal structure of the wavelength demodulator according to the present invention;
FIG. 3 is a schematic side view of a fiber grating sensor array according to the present invention;
FIG. 4 is a cross-sectional view of the internal structure of the fiber grating array inside the battery according to the present invention;
FIG. 5 is a top view of a battery cover of the present invention;
FIG. 6 is a schematic diagram of the fiber grating temperature measurement principle of the present invention;
fig. 7 is a flow chart of the operation of the present invention.
Reference numbers in the figures: 1. a terminal PC; 2. a communication line; 3. a wavelength demodulator; 4. an optical fiber line; 5. a battery; 6. a fiber grating sensor array; 7. an upper cover of the battery; 8. a core package; 9. a battery case.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1-7, the present embodiment provides a method for detecting the internal core temperature of a power battery, the method includes a terminal PC 1, a wavelength demodulator 3, a battery 5 with a built-in fiber grating sensor array 6, an optical fiber 4, and a communication line 2, the terminal PC 1 is connected to the wavelength demodulator 3 through the communication line 2, the battery 5 with the built-in fiber grating sensor array 6 is connected to the wavelength adjuster through the optical fiber 4, the optical fiber 4 is responsible for transmitting emitted light from the wavelength demodulator 3 to the battery 5 with the built-in fiber grating sensor array 6, and transmitting reflected light carrying temperature information from the battery 5 with the built-in fiber grating sensor array 6 to the wavelength demodulator 3, the communication line 2 is responsible for transmitting wavelength temperature encoded digital signals demodulated by the wavelength demodulator 3 to the terminal PC 1, receiving wavelength coding temperature sensing data of different test points in the battery 5 transmitted by the wavelength demodulator 3 through the communication line 2, and calculating and displaying the distribution condition of temperature data in the battery 5 on the terminal PC 1 acquisition software;
the wavelength demodulator 3 comprises a broadband light source emitter, a 3dB coupler, an F-P filter, a photoelectric detection signal amplifier and a data acquisition card, the broadband light source emitter, the 3dB coupler, the F-P filter, the photoelectric detection signal amplifier and the data acquisition card are sequentially connected, the internal broadband light source emitter emits light sources to a battery 5 with a built-in fiber grating sensor array 6 through a fiber line 4 through the 3dB coupler, fiber gratings with different central wavelengths (lambda b1, lambda b2, … and lambda bn) correspond to temperature measurement points in the battery 5 and respectively sense the temperature change of the points to be measured, reflected light carrying temperature information is transmitted to the wavelength demodulator 3 through the fiber line 4, and the wavelength demodulator 3 converts temperature sensing signals with wavelength codes into digital signals and is connected with the terminal PC 1 through the internal data acquisition card;
the battery 5 with the built-in fiber grating sensor array 6 comprises a battery case 9 and a battery upper cover 7 clamped above the battery case 9, a plurality of circles of core packages 8 are wound in the battery case 9, a plurality of fiber grating sensors are arrayed on the core packages 8 and consist of fiber lines 4 and a plurality of fiber gratings with different wavelengths which are connected in series on the fiber lines 4, the internal temperature of the battery 5 is measured by adopting the fiber gratings, the wavelength movement of each fiber grating in each temperature test point in the battery 5 in the temperature measurement range cannot be superposed with each other by utilizing wavelength division multiplexing and time division multiplexing, and the accurate measurement of the distribution condition of the internal temperature data of the battery 5 is realized by pre-embedding the designed fiber grating sensor array 6 in the battery 5.
The fiber bragg grating belongs to a passive device, has the characteristics of corrosion resistance, electromagnetic interference resistance and the like, accurately measures the core temperature distribution data in the battery 5 through the change of the reflection wavelength of an optical signal in the fiber bragg grating, does not worry about the influence of an electric signal on the battery 5, and synchronously reduces the influence on the electrochemical reaction of the power battery 5;
in addition, the fiber bragg grating is a grating with a certain spatial phase formed in the fiber core of the optical fiber by using the photosensitive characteristic of the fiber material through processes such as ultraviolet exposure and the like, the period and the refractive index of the grating can be changed due to the temperature acting on the grating, the wavelength of reflected light can be changed, the change of the temperature of each measuring point in the battery 5 can be measured by detecting the change of the wavelength of the reflected light, and fig. 6 is a schematic diagram of the temperature measurement principle of the fiber bragg grating;
according to the coupled mode theory of the fiber grating, the wavelength of the reflected light center wave reflected by the fiber grating
Effective refractive index of grating
And grating period
Satisfies the following relation:
the relation between the temperature and the wavelength change of the fiber grating obtained by taking the derivative of the temperature in the formula (1) is as follows:
in the formula:
the coefficient of thermal expansion of the optical fiber mainly causes the periodic variation of the grating grid;
is the thermo-optic coefficient of the fiber, mainly causing the change of the refractive index of the fiber;
representing the elasto-optic effect caused by thermal expansion;
representing the waveguide effect due to the change in the core diameter of the optical fiber due to thermal expansion,
in order to change the amount of wavelength change,
is the temperature variation.
The specific working principle is as follows: the method for detecting the core temperature inside a power battery provided by this embodiment includes powering on and starting a terminal PC 1 and a wavelength demodulator 3, where the wavelength demodulator 3 transmits a preset broadband light source signal to the inside of a battery 5 through an optical fiber line 4, the battery 5 with an array of built-in fiber grating sensors reflects reflected light with different wavelengths and reflected light with different wavelengths to the wavelength demodulator 3 through the optical fiber line 4 according to temperature variation conditions of different temperature test points inside the battery 5, the wavelength demodulator 3 filters and encodes the reflected light signals with different wavelengths carrying the temperature signals of the different temperature test points inside the battery 5, converts the wavelength-encoded temperature sensing signal into a digital signal, a data acquisition card built in the wavelength demodulator 3 transmits wavelength encoded data to the terminal PC 1 through a communication line 2, and the terminal PC 1 transmits the acquired wavelength encoded data according to the acquired wavelength encoded data, according to the relation between the wavelength change of the reflected light and the temperature change of the formula (2), the distribution condition of the internal temperature data of the battery 5 is calculated and displayed, and the internal core temperature data of the battery 5 is calculated and obtained.
In summary, the present embodiment provides a method for detecting the core temperature inside a power battery,
1. the method has the advantages that the core temperature inside the power battery 5 can be reliably measured to obtain the highest temperature inside the power battery 5;
2. the problems that the core temperature sampling method in the power battery 5 affects the winding of the battery core, and the problems that the power battery 5 deforms and current distribution is uneven are reduced due to the fact that the fiber bragg grating has the physical characteristics of small size, flexibility, easiness in winding and the like and is thin relative to the winding of the battery 5;
3. the complexity of a temperature measurement system is reduced, the fiber bragg grating array can be laid in a winding layer inside the battery 5 according to a designed shape, the measurement area of the core temperature inside the power battery 5 is increased, and the maximum value of the core inside the power battery 5 is accurately measured;
4. the problem that the safety of the battery 5 is influenced by a temperature probe measuring mode is solved, the adopted fiber bragg grating belongs to a passive device, has the characteristics of corrosion resistance, electromagnetic interference resistance and the like, core temperature distribution data in the battery 5 are accurately measured through the change of the reflection wavelength of an optical signal in the fiber bragg grating, the influence of an electric signal on the battery 5 is not needed to be worried about, and the influence on the electrochemical reaction of the power battery 5 is synchronously reduced;
5. the fiber bragg grating is adopted to measure the internal temperature of the battery 5, real-time acquisition can be realized, the acquisition time can be less than 10MS, and the rapid detection of the temperature change of the power battery 5 is realized; and the temperature inside the battery 5 can be measured in a networking way by utilizing wavelength division multiplexing and time division multiplexing, and the temperature distribution conditions of different measuring points inside the battery 5 can be obtained.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.