A fiber grating temperature sampling system for power batteries

Abstract

The present invention discloses a power battery fiber Bragg grating temperature sampling system, including a main controller module and a slave control module. A fiber Bragg grating sensor is arranged on the power battery, and the fiber Bragg grating sensor is connected to each single cell on the power battery at the same time; the slave control module includes a front-end sampling module, a fiber Bragg grating demodulation module and a communication interaction module; the communication interaction module includes a communication module and an MCU module; the front-end sampling module collects the voltage and first temperature data of the single cell; the fiber Bragg grating demodulator module includes a scanning light source and a demodulator, the MCU module receives and processes the data from the front-end sampling module and the fiber Bragg grating demodulator module, and the MCU module exchanges information with the main controller module through the communication module. In the present invention, the fiber Bragg grating demodulation module and the fiber Bragg grating sensor are used to detect the temperature of each single cell in the power battery, which can effectively meet the temperature detection requirements of the existing power battery system for a single cell.

Description

Technical Field

[0001] The invention relates to the technical field of battery management, in particular to a fiber grating temperature sampling system for a power battery. Background Art

[0002] With the advancement of science and technology and the increasing demand for clean energy, lithium-ion batteries, as efficient and environmentally friendly energy storage devices, are becoming an important part of the future energy field. Driven by the development of the electric vehicle market and renewable energy, lithium-ion battery technology continues to evolve. At present, new energy lithium-ion power batteries have been fully developed in many fields such as new energy vehicles, energy storage, and aviation EVTOL. However, due to their high energy density and chemical properties, if lithium-ion batteries are abused or have quality problems, individual cells will fail, resulting in increased temperature rise differences. In more serious cases, thermal runaway of single cells will lead to serious safety accidents and property losses.

[0003] For new energy power batteries, BMS (power battery management system) is the brain of the power battery, responsible for monitoring the temperature, voltage and other information of the entire battery system, and timely cutting off the power output to protect the power battery before safety events such as overheating occur. The current power battery management system is mainly divided into two large modules, one is BCU (power battery master controller), which is responsible for receiving temperature and voltage information from CMU (slave control unit), calculating and diagnosing the power battery status, and making decisions on whether to protect when the underlying sampling data is abnormal. The CMU module (slave control unit) is responsible for monitoring the temperature and voltage information of the power battery cells.

[0004] In the current mainstream CMU (control unit) architecture, the unit for sampling temperature and voltage data is the IC-AFE front-end sampling chip. Due to resource and function limitations, this chip only supports very limited GPIO interfaces, that is, it only supports 8-10 NTC battery temperature sampling. For example, mainstream chips such as LTC681X / MC3377X / TI 79616 only support a relatively limited number of battery cell NTC temperature sampling. Most of the current EV new energy vehicles or EVTOL (electric vertical take-off and landing aircraft) power batteries have more than 200 strings of single cells. The traditional CMU architecture solution has difficulty in fully monitoring the temperature of all single cells on the power battery, and therefore cannot meet the higher safety and performance requirements of the power battery system. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and provide a power battery fiber Bragg grating temperature sampling system.

[0006] The object of the present invention is achieved through the following technical solutions: a power battery fiber Bragg grating temperature sampling system, comprising a main controller module and a slave control module, a fiber Bragg grating sensor is arranged on the power battery, and the fiber Bragg grating sensor is simultaneously connected to each single cell on the power battery;

[0007] The slave control module includes a front-end sampling module, a fiber Bragg grating demodulation module and a communication interaction module; the communication interaction module includes a communication module and an MCU module;

[0008] The front-end sampling module collects the voltage and first temperature data of the single cell; the fiber Bragg grating demodulator module includes a scanning light source and a demodulator, the scanning light source inputs incident laser to the fiber Bragg grating sensor, the demodulator receives the reflected laser signal reflected by the fiber Bragg grating sensor, and the computing unit in the demodulator calculates the reflected laser signal and obtains the second temperature data of each single cell;

[0009] The MCU module receives and processes data from the front-end sampling module and the fiber grating demodulator module, and the MCU module exchanges information with the main controller module through the communication module.

[0010] Preferably, the communication module is a CAN module.

[0011] Preferably, the wavelength of the incident laser is 1528nm-1568nm, and the step of the incident laser is 8pm.

[0012] Preferably, the main controller module is connected to the wake-up module; when it is detected that the first temperature data value of the single cell exceeds the temperature threshold, the power battery fiber Bragg grating temperature sampling system is awakened from the sleep state through the wake-up module.

[0013] Preferably, the main controller module is connected to a high-voltage voltage acquisition module, and when the voltage acquired by the high-voltage voltage acquisition module is higher than a voltage threshold, the main controller module issues an alarm.

[0014] Preferably, the front-end sampling module uses an AFE chip to collect the voltage and first temperature data of the single cell.

[0015] Preferably, a clamping and fixing mechanism is provided on the single cell battery, and the clamping and fixing mechanism includes an elastic pressing plate and a thermal sensing pressing plate, one end of the elastic pressing plate is a fixed end, which is fixedly connected to the shell of the single cell battery, and the other end of the elastic pressing plate is a movable end; one end of the thermal sensing pressing plate is fixed to the shell of the single cell battery through a heat-conducting connecting bracket, and the other end of the thermal sensing pressing plate is a free end; the free end on the thermal sensing pressing plate is in contact with the movable end on the elastic pressing plate, and the free end on the thermal sensing pressing plate is located on the outside of the movable end on the elastic pressing plate; the fiber grating sensor is sandwiched between the elastic pressing plate and the shell of the single cell battery; the thermal sensing pressing plate is composed of a first material layer and a second material layer, and the second material layer is located on the side of the first material layer away from the second material layer; the thermal expansion coefficient of the second material layer is greater than the thermal expansion coefficient of the first material layer.

[0016] Preferably, a positioning block is provided on one side of the elastic pressing sheet close to the single cell housing, and a positioning groove for positioning the light grating sensor is provided on the positioning block.

[0017] Preferably, a thermally conductive silicone pad is provided on the outer shell of the single cell, and the fiber grating sensor is located between the elastic pressing sheet and the thermally conductive silicone pad.

[0018] Preferably, the elastic pressing sheet is made of spring steel.

[0019] The beneficial effects of the present invention are:

[0020] 1. In the present invention, the temperature of each single cell in the power battery is detected by a fiber optic Bragg grating demodulation module and a fiber optic Bragg grating sensor. The fiber optic Bragg grating demodulation module uses the fiber optic temperature measurement technology, and the fiber optic Bragg grating sensor is arranged so that the temperature measurement range can cover all single cells, thereby effectively meeting the temperature detection requirements of the existing power battery system for a single cell, greatly improving the coverage of the temperature detection of the single cell, and effectively avoiding the problem that the temperature sampling points of the current traditional architecture cannot completely cover the number of cells, ensuring that all single cells can be effectively detected once thermal runaway or thermal events occur, thereby ensuring the safe use of the power battery.

[0021] 2. The front-end sampling module can serve as a redundant backup for the fiber Bragg grating demodulation module. If the fiber Bragg grating demodulation module fails, the backup front-end sampling module can continuously collect basic temperature data of the power battery to ensure continuous monitoring of the power battery temperature.

[0022] 3. In the present invention, the fiber Bragg grating demodulation module and the front-end sampling module are designed to be compatible, backing up each other in the temperature detection function, and having the ability to monitor the temperature of all single cells; and this compatible system design reduces the cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the fiber Bragg grating temperature sampling system for power batteries of the present invention.

[0024] Figure 2 This is a schematic diagram of the fiber Bragg grating sensor connected to a single cell.

[0025] Figure 3 It is a structural schematic diagram of the clamping and fixing mechanism.

[0026] In the figure: 1. Single cell, 2. Pressing and fixing mechanism, 2-1. Elastic pressing sheet, 2-2. Thermal conductive silicone pad, 2-3. Positioning block, 2-4. Thermal conductive connecting bracket, 2-5. Thermal sensing pressing sheet, 2-5a. First material layer, 2-5b. Second material layer, 3. Fiber Bragg grating sensor. DETAILED DESCRIPTION

[0027] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0028] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0029] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0030] like Figures 1 to 3As shown, a power battery fiber Bragg grating temperature sampling system includes a main controller module (BCU) and a slave control module. A fiber Bragg grating sensor 3 is arranged on the power battery, and the fiber Bragg grating sensor 3 is connected to each single battery cell 1 on the power battery at the same time; the slave control module includes a front-end sampling module, a fiber Bragg grating demodulation module and a communication interaction module; the communication interaction module includes a communication module and an MCU module; the front-end sampling module collects the voltage and first temperature data of the single battery cell 1; the fiber Bragg grating demodulator module includes a scanning light source and a demodulator, the scanning light source inputs an incident laser to the fiber Bragg grating sensor 3, the demodulator receives a reflected laser signal reflected by the fiber Bragg grating sensor 3, and the operation unit in the demodulator performs a solution according to the reflected laser signal and obtains the second temperature data of each single battery cell 1; the MCU module receives and processes the data from the front-end sampling module and the fiber Bragg grating demodulator module, and the MCU module exchanges information with the main controller module (BCU) through the communication module.

[0031] In the present invention, the control unit (CMU) includes a front-end sampling module, a fiber Bragg grating demodulation module and a communication interaction module, wherein the front-end sampling module is mainly responsible for collecting the voltage and temperature of the single cell 1. The fiber Bragg grating demodulation module detects the temperature of each single cell in the power battery through the fiber Bragg grating sensor 3. The fiber Bragg grating demodulation module uses the fiber temperature measurement technology and the fiber Bragg grating sensor 3 to enable the temperature measurement range to cover all single cells 1, thereby effectively meeting the temperature detection requirements of the existing power battery system for a single cell, greatly improving the coverage of the temperature detection of the single cell 1, and effectively avoiding the problem that the temperature sampling points of the current traditional architecture cannot completely cover the number of cells, ensuring that all single cells can be effectively detected once thermal runaway or thermal events occur, and ensuring the safety of the power battery. The traditional power battery management system control scheme generally does not exceed the maximum monitoring of 60 temperature sampling points, and usually 3-4 single cells share a temperature sensor or thermistor (NTC), which will cause the thermal runaway or thermal events of the remote single cells to be unable to be effectively detected, which is easy to cause safety accidents.

[0032] The front-end sampling module in the present invention mainly adopts the traditional front-end sampling chip architecture. The front-end sampling module includes several AFE chips to collect the temperature of the power battery, and each AFE chip supports 8-10 temperature collection points. A temperature sensor or thermistor (NTC) is provided at the temperature collection point of the single cell, so as to realize the temperature collection of the single cell. Usually, 3-4 single cells share one temperature sensor or thermistor (NTC). This mode is mature in technology and can perform relatively basic temperature detection on the power battery. In terms of temperature detection of single cells, the front-end sampling module can be used as a redundant backup of the fiber Bragg grating demodulation module. If the fiber Bragg grating demodulation module fails, the backup front-end sampling module can continuously collect the basic temperature data of the power battery to ensure continuous monitoring of the power battery temperature.

[0033] In the present invention, the fiber Bragg grating demodulation module and the front-end sampling module are designed to be compatible, backing up each other in the temperature detection function, and having the ability to monitor the temperature of all single cells; and this compatible system design reduces the cost of the system.

[0034] Among them, the demodulator can support a maximum of 126 channels, each channel can be compatible with at least 8 temperature detection points, so the demodulator can support a total of 1008 battery cell temperature detection points, which can effectively meet the temperature detection needs of power batteries for EV new energy vehicles or EVTOL (electric vertical take-off and landing aircraft) on the market.

[0035] In this embodiment, the computing unit in the demodulator adopts a SOC chip.

[0036] In this embodiment, the communication module is a CAN module. The communication module can also use RS485, RS232, Ethernet, SPI, IIC and other communication topologies.

[0037] The wavelength of the incident laser generated by the scanning light source is 1528nm-1568nm, and the step of the incident laser is 8pm. The scanning frequency of the scanning light source is set to 5Khz. The incident laser is transmitted to the deployed fiber grating sensor through a splitter. The fiber grating sensor is based on the temperature sensitivity of the Bragg wavelength. When the temperature changes, the refractive index and grating period of the optical fiber are affected, which leads to the movement of the Bragg wavelength; by monitoring the change of the Bragg wavelength, the temperature can be accurately measured.

[0038] Furthermore, the main controller module is connected to the wake-up module; when it is detected that the first temperature data value of the single cell 1 exceeds the temperature threshold, the power battery fiber Bragg grating temperature sampling system is awakened from the sleep state through the wake-up module. After the power battery fiber Bragg grating temperature sampling system completes a complete power battery status check, if there is no emergency at present, the power battery fiber Bragg grating temperature sampling system will enter the sleep mode. In the sleep mode, unnecessary circuits and sensors will be turned off, the power supply to the wake-up module will be retained, and the monitoring of the temperature of the single cell will be maintained; when it is detected that the temperature value of the single cell exceeds the temperature threshold, the wake-up module will switch the power battery fiber Bragg grating temperature sampling system from the sleep state to the working state.

[0039] The main controller module is connected to the high-voltage voltage acquisition module. When the voltage acquired by the high-voltage voltage acquisition module is higher than the voltage threshold, the main controller module issues an alarm.

[0040] When the power battery supplies power to an external load, the positive electrode of the power battery is connected to the external load through a positive cable, and the negative electrode of the power battery is connected to the external load through a negative cable. The positive cable is provided with a fuse module and a relay module, and the negative cable is provided with a current sensor module. The current sensor module detects the power supply current, and the current sensor module is connected to the main controller module (BCU) to feed back the current current to the main controller module.

[0041] like Figures 2 to 3 As shown, in order to realize the installation of the fiber grating sensor 3, a clamping and fixing mechanism 2 is provided on the single cell 1, and the clamping and fixing mechanism 2 includes an elastic pressing sheet 2-1 and a thermal sensing pressing sheet 2-5. One end of the elastic pressing sheet 2-1 is a fixed end, which is fixedly connected to the shell of the single cell 1, and the other end of the elastic pressing sheet 2-1 is a movable end; one end of the thermal sensing pressing sheet 2-5 is fixed to the shell of the single cell 1 through a heat-conducting connecting bracket 2-4, and the other end of the thermal sensing pressing sheet 2-5 is a free end; the free end on the thermal sensing pressing sheet 2-5 is fixed to the shell of the single cell 1 through a heat-conducting connecting bracket 2-4, and the other end of the thermal sensing pressing sheet 2-5 is a free end; The active ends on the elastic pressing sheet 2-1 are in contact, and the free end on the thermal sensing pressing sheet 2-5 is located on the outside of the active end on the elastic pressing sheet 2-1; the fiber grating sensor 3 is clamped between the elastic pressing sheet 2-1 and the outer shell of the single battery cell 1; the thermal sensing pressing sheet 2-5 is composed of a first material layer 2-5a and a second material layer 2-5b, and the second material layer 2-5b is located on the side of the first material layer 2-5a away from the second material layer 2-5b; the thermal expansion coefficient of the second material layer 2-5b is greater than the thermal expansion coefficient of the first material layer 2-5a.

[0042] The fiber grating sensor 3 will pass through each single cell 1, and the contact position between the fiber grating sensor 3 and the single cell 1 is the temperature detection point. In the present invention, when the fiber grating sensor 3 is arranged, the fiber grating sensor 3 is pressed and fixed by the pressing and fixing mechanism 2, so that the fiber grating sensor 3 contacts the outer shell of the single cell 1 and obtains the temperature of the outer shell. The elastic pressing sheet 2-1 and the heat-sensing pressing sheet 2-5 both have a certain elasticity.

[0043] An opening is formed between the movable end of the elastic pressing sheet 2-1 and the battery cell shell. During installation, the fiber grating sensor 3 is passed between the movable end on the elastic pressing sheet 2-1 and the free end on the heat-sensing pressing sheet 2-5, and the installation point on the fiber grating sensor 3 is located between the elastic pressing sheet 2-1 and the shell. The fiber grating sensor 3 is pressed against the shell by the elastic pressing sheet 2-1, and the fiber grating sensor 3 is tightly attached to the shell by the elastic force of the elastic pressing sheet 2-1, thereby completing the connection between the fiber grating sensor 3 and the single battery cell 1. This installation method is relatively simple. Compared with the traditional method of bonding by tape or glue, this installation method of the present invention has good stability and is firmly installed, and there is no problem of aging and falling off of glue or tape.

[0044] When the single battery cell 1 is in operation, the battery will generate heat, and the heat will be transferred to the heat-sensing pressing plate 2-5 to increase the temperature of the heat-sensing pressing plate 2-5. When the temperature of the heat-sensing pressing plate 2-5 rises, since the thermal expansion coefficient of the second material layer 2-5b is greater than the thermal expansion coefficient of the first material layer 2-5a, the thermal expansion amount of the second material layer 2-5b is greater than the thermal expansion amount of the first material layer 2-5a during the temperature rise process, so that the free end of the heat-sensing pressing plate 2-5 bends and moves toward the shell. The movement of the free end will drive the active end of the elastic pressing plate 2-1 to move toward the shell, thereby increasing the clamping force of the elastic pressing plate 2-1 on the fiber grating sensor 3, thereby ensuring that the fiber grating sensor 3 can be firmly attached to the shell during the temperature measurement process, thereby ensuring the effectiveness of the temperature measurement. On the contrary, when the power battery is in a non-working state, the fiber grating sensor 3 is also in a non-working state, the power battery temperature is low (consistent with room temperature), and the thermal sensing pressing plate 2-5 will return to its initial state, thereby reducing the pressing force of the elastic pressing plate 2-1 on the fiber grating sensor 3, so that the fiber grating sensor 3 is protected from excessive pressing force when in a non-working state, thereby reducing the probability of damage to the fiber grating sensor 3 due to excessive pressure for a long time.

[0045] In this embodiment, the first material layer 2-5a and the second material layer 2-5b are both made of metal materials. The elastic pressing sheet 2-1 is made of spring steel.

[0046] A positioning block 2-3 is provided on one side of the elastic pressing sheet 2-1 close to the shell of the single cell 1, and a positioning groove for positioning the optical fiber grating sensor is provided on the positioning block 2-3. One side of the optical fiber grating sensor 3 is embedded in the positioning groove on the positioning block 2-3, thereby realizing the positioning of the optical fiber grating sensor 3 and preventing the position of the optical fiber grating sensor 3 from slipping.

[0047] Furthermore, a thermally conductive silicone pad 2 - 2 is provided on the outer shell of the single battery cell 1 , and the fiber grating sensor 3 is located between the elastic pressing sheet 2 - 1 and the thermally conductive silicone pad 2 - 2 .

[0048] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A power battery fiber Bragg grating temperature sampling system, characterized in that: It includes a main controller module and a slave control module. A fiber grating sensor is arranged on the power battery, and the fiber grating sensor is connected to each single cell on the power battery at the same time; The slave control module includes a front-end sampling module, a fiber Bragg grating demodulation module and a communication interaction module; the communication interaction module includes a communication module and an MCU module; The front-end sampling module collects the voltage and first temperature data of the single cell; the fiber Bragg grating demodulator module includes a scanning light source and a demodulator, the scanning light source inputs incident laser to the fiber Bragg grating sensor, the demodulator receives the reflected laser signal reflected by the fiber Bragg grating sensor, and the computing unit in the demodulator performs calculation according to the reflected laser signal and obtains the second temperature data of each single cell; The MCU module receives and processes data from the front-end sampling module and the fiber Bragg grating demodulator module, and the MCU module exchanges information with the main controller module through the communication module; The single cell is provided with a clamping and fixing mechanism, which includes an elastic pressing sheet and a heat-sensing pressing sheet, one end of the elastic pressing sheet is a fixed end, which is fixedly connected to the shell of the single cell, and the other end of the elastic pressing sheet is a movable end; One end of the thermal sensing pressing sheet is fixed to the shell of the single cell through a heat-conducting connecting bracket, and the other end of the thermal sensing pressing sheet is a free end; the free end on the thermal sensing pressing sheet contacts the movable end on the elastic pressing sheet, and the free end on the thermal sensing pressing sheet is located outside the movable end on the elastic pressing sheet; the fiber grating sensor is sandwiched between the elastic pressing sheet and the shell of the single cell; The heat induction pressing sheet is composed of a first material layer and a second material layer, wherein the second material layer is located on a side of the first material layer away from the second material layer; The thermal expansion coefficient of the second material layer is greater than the thermal expansion coefficient of the first material layer.

2. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: The communication module is a CAN module.

3. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: The wavelength of the incident laser is 1528nm-1568nm, and the step of the incident laser is 8pm.

4. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: The main controller module is connected to the wake-up module; when it is detected that the first temperature data value of the single cell exceeds the temperature threshold, the power battery fiber Bragg grating temperature sampling system is awakened from the dormant state through the wake-up module.

5. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: The main controller module is connected to the high-voltage voltage acquisition module. When the voltage acquired by the high-voltage voltage acquisition module is higher than the voltage threshold, the main controller module issues an alarm.

6. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: The front-end sampling module uses an AFE chip to collect voltage and first temperature data of a single cell.

7. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: A positioning block is provided on one side of the elastic pressing sheet close to the single cell shell, and a positioning groove for positioning the light grating sensor is provided on the positioning block.

8. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: A heat-conducting silicone pad is arranged on the shell of the single cell, and the fiber grating sensor is located between the elastic pressing sheet and the heat-conducting silicone pad.

9. A power battery fiber Bragg grating temperature sampling system according to claim 1, characterized in that: The elastic pressing sheet is made of spring steel.

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