Lithium battery temperature acquisition device based on thermocouple

Abstract

The invention provides a thermocouple-based lithium battery temperature acquisition device in the technical field of lithium battery temperature detection. The thermocouple-based lithium battery temperature acquisition device comprises an RS485 communication module, a single chip microcomputer, a plurality of sampling modules and a plurality of thermocouples, one end of the single-chip microcomputer is connected with the RS485 communication module, and the other end of the single-chip microcomputer is connected with each sampling module; each thermocouple is connected with a sampling module; the RS485 communication module comprises an RS485 communication chip U2, a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a capacitor C10, a diode clamping circuit D3 and a wiring terminal J4. The lithium battery temperature acquisition system has the advantage that the lithium battery temperature acquisition precision and reliability are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery temperature detection, and in particular to a lithium battery temperature acquisition device based on a thermocouple. Background Art

[0002] The performance of lithium batteries is affected by many parameters, among which temperature is the most important one. Whether in the power supply system of electric vehicles or in the battery testing process, attention to temperature is essential, because temperature directly affects the internal resistance, charge and discharge characteristics, safety and service life of lithium batteries. The performance of lithium batteries is limited in low temperature environments, and their average discharge voltage and discharge capacity will both decrease. Excessive temperature will lead to uneven aging of lithium batteries and increased safety risks.

[0003] Real-time temperature acquisition, over-temperature alarm, and temperature control over a long distance through the network are the inevitable trends in the development of modern temperature measurement technology. In the lithium battery formation process, it is very important to acquire the temperature of the battery cell and the environment. By acquiring the temperature, it is possible to prevent temperature anomalies, quickly make dangerous judgments, improve production safety, and ensure the production quality of lithium batteries.

[0004] Thermocouples are a common type of temperature sensor, and are widely used due to their relatively low price, wide temperature range, long-term stability, and suitability for contact measurement. A thermocouple is a section of two wires made of different conductors (usually alloys) welded together at one end. Whenever a conductor experiences a temperature gradient from one end to the other, an electromotive force is generated. This electromotive force rises due to the diffusion of free electrons in the conductor at different rates (depending on the temperature). The diffusion rate of electrons with higher energy at the hot end of the conductor is faster than the diffusion rate of electrons with lower energy at the cold end. The net effect is that there is a buildup of charge at one end of the conductor and an electromotive force is generated between the hot and cold ends.

[0005] The traditional temperature measurement method of thermocouples is to connect the two ports of the thermocouple to a thermometer or a digital multimeter, and then read the temperature value. The traditional method does not require additional equipment and is easy to measure. However, due to the characteristics of the thermocouple itself, it is easily affected by the surrounding environment, and the measured data sometimes has large errors, which in turn affects the accuracy of lithium battery temperature acquisition; during the lithium battery formation process, it is necessary to connect several measurement channels at the same time for temperature acquisition, which is prone to wiring errors, resulting in measurement channel acquisition errors, and the reliability of lithium battery temperature acquisition cannot be guaranteed, which in turn affects the safety and quality of lithium battery formation.

[0006] Therefore, how to provide a lithium battery temperature acquisition device based on thermocouples to improve the accuracy and reliability of lithium battery temperature acquisition has become a technical problem that needs to be solved urgently. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a lithium battery temperature acquisition device based on a thermocouple to improve the accuracy and reliability of lithium battery temperature acquisition.

[0008] The present invention is implemented as follows: A lithium battery temperature acquisition device based on thermocouples includes an RS485 communication module, a single-chip microcomputer, a plurality of sampling modules and a plurality of thermocouples;

[0009] One end of the single chip microcomputer is connected to the RS485 communication module, and the other end is connected to each sampling module; each of the thermocouples is connected to a sampling module respectively;

[0010] The RS485 communication module includes an RS485 communication chip U2, a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a capacitor C10, a diode clamp circuit D3 and a wiring terminal J4;

[0011] Pin 1 of the RS485 communication chip U2 is connected to one end of a resistor R35, pins 2 and 3 are connected to one end of a resistor R37, pin 4 is connected to one end of a resistor R40, pin 6 is connected to one end of a resistor R39 and a resistor R41, pin 7 is connected to one end of a resistor R34 and a resistor R38, and pin 8 is connected to one end of a capacitor C10;

[0012] The other end of the resistor R35 is connected to the single chip microcomputer; the other end of the resistor R37 is connected to the resistor R33 and the single chip microcomputer; the other end of the resistor R40 is connected to the resistor R42 and the single chip microcomputer;

[0013] One end of the diode clamp circuit D3 is connected to the other end of the resistor R38 and the pin 1 of the connection terminal J4, and the other end is connected to the other end of the resistor R39 and the pin 2 of the connection terminal J4.

[0014] Further, the sampling module includes an analog-to-digital conversion chip U5, a digital isolation chip U4, a resistor R50, a resistor R53, a resistor R54, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R62, a resistor R63, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28, a capacitor C29, a capacitor C30, a capacitor C31, a capacitor C33, a capacitor C34, a capacitor C35, a capacitor C36, a clamping diode D6, a diode D4 and an inductor L2;

[0015] One end of the resistor R57 is connected to the resistor R53 and the positive electrode of the thermocouple, and the other end is connected to the capacitor C30, one end of the capacitor C31 and the pin 4 of the analog-to-digital conversion chip U5; one end of the resistor R62 is connected to the resistor R63 and the negative electrode of the thermocouple, and the other end is connected to the capacitor C36, the other end of the capacitor C31 and the pin 5 of the analog-to-digital conversion chip U5; after the capacitor C33 is connected in parallel with the clamping diode D6, one end is connected to the pin 8 of the analog-to-digital conversion chip U5, and the other end is connected to the pins 6 and 7 of the analog-to-digital conversion chip U5;

[0016] One end of the resistor R50 is connected to pin 10 of the analog-to-digital conversion chip U5, and the other end is connected to pin 14 of the digital isolation chip U4; one end of the resistor R59 is connected to pin 9 of the analog-to-digital conversion chip U5, and the other end is connected to pin 11 of the digital isolation chip U4; one end of the resistor R54 is connected to pin 1 of the analog-to-digital conversion chip U5, and the other end is connected to pin 13 of the digital isolation chip U4; one end of the resistor R58 is connected to pin 2 of the analog-to-digital conversion chip U5, and the other end is connected to pin 12 of the digital isolation chip U4;

[0017] After the capacitor C25 and the capacitor C27 are connected in parallel, one end of the capacitor C25 is connected to one end of the inductor L2 and the pin 16 of the digital isolation chip U4, and the other end is connected to one end of the resistor R60; one end of the capacitor C26 is connected to the other end of the resistor R60, and the other end is connected to the other end of the inductor L2;

[0018] After the capacitor C28 and the capacitor C29 are connected in parallel, one end is connected to pin 1 of the digital isolation chip U4 and the single-chip microcomputer, and the other end is grounded; after the capacitor C34 and the capacitor C35 are connected in parallel, one end is connected to pin 7 of the digital isolation chip U4, and the other end is grounded; the input end of the diode D4 is connected to the single-chip microcomputer, and the output end is connected to pin 6 of the digital isolation chip U4; pins 2, 3, 4, and 5 of the digital isolation chip U4 are all connected to the single-chip microcomputer.

[0019] Furthermore, the number of the sampling modules is 16.

[0020] Furthermore, the number of the thermocouples is 16.

[0021] Furthermore, the model of the RS485 communication chip U2 is TPT75176.

[0022] Furthermore, the model of the single chip microcomputer is STM32F429.

[0023] Furthermore, the model of the analog-to-digital conversion chip U5 is ADS1118.

[0024] Furthermore, the model of the digital isolation chip U4 is NSIP8841W1.

[0025] The advantages of the present invention are:

[0026] By setting up an RS485 communication module, a single-chip microcomputer, a sampling module and a thermocouple; one end of the single-chip microcomputer is connected to the RS485 communication module, and the other end is connected to each sampling module; each thermocouple is connected to a sampling module respectively; since the resistor R53, resistor R57, resistor R62, resistor R63, capacitor C30, capacitor C31 and capacitor C36 of the sampling module constitute a first-order filter to filter the temperature signal input by the thermocouple, the interference is isolated by the digital isolation chip U4 of the sampling module, and the cold end of the thermocouple is compensated in combination with the temperature sensor provided by the analog-to-digital conversion chip U5 of the sampling module, thereby greatly improving the accuracy of lithium battery temperature acquisition; by setting the model of the analog-to-digital conversion chip U5 to ADS1118, it supports 16-channel temperature signal acquisition, and each channel has an open circuit detection function, which eliminates the hidden dangers caused by line sequence errors, thereby greatly improving the reliability of lithium battery temperature acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0028] Figure 1 The present invention is a circuit principle block diagram of a lithium battery temperature acquisition device based on a thermocouple.

[0029] Figure 2 It is a circuit diagram of the RS485 communication module of the present invention.

[0030] Figure 3 Schematic diagram of the sampling module of the present invention. DETAILED DESCRIPTION

[0031] The technical solution in the embodiment of the present application has the following overall idea: the resistor R53, resistor R57, resistor R62, resistor R63, capacitor C30, capacitor C31 and capacitor C36 of the sampling module form a first-order filter to filter the temperature signal, and the interference is isolated by the digital isolation chip U4. The temperature sensor provided by the analog-to-digital conversion chip U5 is combined to compensate the cold end of the thermocouple to improve the accuracy of lithium battery temperature acquisition; by setting the model of the analog-to-digital conversion chip U5 to ADS1118, 16-channel temperature signal acquisition is supported, and each channel has an open circuit detection function, which eliminates the hidden dangers caused by line sequence errors and improves the reliability of lithium battery temperature acquisition.

[0032] Please refer to Figures 1 to 3As shown, a preferred embodiment of a lithium battery temperature acquisition device based on a thermocouple of the present invention comprises an RS485 communication module, a single-chip microcomputer, a plurality of sampling modules and a plurality of thermocouples; the RS485 communication module is used to communicate with a host computer; the single-chip microcomputer is used to control the operation of the lithium battery temperature acquisition device; the sampling module is used to collect and perform analog-to-digital conversion on the temperature signal of the thermocouple; the thermocouple is used to sense the temperature of the lithium battery;

[0033] One end of the single chip microcomputer is connected to the RS485 communication module, and the other end is connected to each sampling module; each of the thermocouples is connected to a sampling module respectively;

[0034] The RS485 communication module includes an RS485 communication chip U2, a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a capacitor C10, a diode clamp circuit D3 and a wiring terminal J4;

[0035] Pin 1 of the RS485 communication chip U2 is connected to one end of a resistor R35, pins 2 and 3 are connected to one end of a resistor R37, pin 4 is connected to one end of a resistor R40, pin 6 is connected to one end of a resistor R39 and a resistor R41, pin 7 is connected to one end of a resistor R34 and a resistor R38, and pin 8 is connected to one end of a capacitor C10;

[0036] The other end of the resistor R35 is connected to the single chip microcomputer; the other end of the resistor R37 is connected to the resistor R33 and the single chip microcomputer; the other end of the resistor R40 is connected to the resistor R42 and the single chip microcomputer;

[0037] One end of the diode clamp circuit D3 is connected to the other end of the resistor R38 and the pin 1 of the connection terminal J4, and the other end is connected to the other end of the resistor R39 and the pin 2 of the connection terminal J4.

[0038] The sampling module includes an analog-to-digital conversion chip U5, a digital isolation chip U4, a resistor R50, a resistor R53, a resistor R54, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R62, a resistor R63, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28, a capacitor C29, a capacitor C30, a capacitor C31, a capacitor C33, a capacitor C34, a capacitor C35, a capacitor C36, a clamping diode D6, a diode D4 and an inductor L2; the analog-to-digital conversion chip U5 is spaced a certain distance from the digital isolation chip U4 to prevent the digital isolation chip U4 from heating up and affecting the sampling accuracy of the temperature sensor inside the analog-to-digital conversion chip U5;

[0039] One end of the resistor R57 is connected to the resistor R53 and the positive electrode of the thermocouple, and the other end is connected to the capacitor C30, one end of the capacitor C31 and the pin 4 of the analog-to-digital conversion chip U5; one end of the resistor R62 is connected to the resistor R63 and the negative electrode of the thermocouple, and the other end is connected to the capacitor C36, the other end of the capacitor C31 and the pin 5 of the analog-to-digital conversion chip U5; after the capacitor C33 is connected in parallel with the clamping diode D6, one end is connected to the pin 8 of the analog-to-digital conversion chip U5, and the other end is connected to the pins 6 and 7 of the analog-to-digital conversion chip U5;

[0040] One end of the resistor R50 is connected to pin 10 of the analog-to-digital conversion chip U5, and the other end is connected to pin 14 of the digital isolation chip U4; one end of the resistor R59 is connected to pin 9 of the analog-to-digital conversion chip U5, and the other end is connected to pin 11 of the digital isolation chip U4; one end of the resistor R54 is connected to pin 1 of the analog-to-digital conversion chip U5, and the other end is connected to pin 13 of the digital isolation chip U4; one end of the resistor R58 is connected to pin 2 of the analog-to-digital conversion chip U5, and the other end is connected to pin 12 of the digital isolation chip U4;

[0041] After the capacitor C25 and the capacitor C27 are connected in parallel, one end of the capacitor C25 is connected to one end of the inductor L2 and the pin 16 of the digital isolation chip U4, and the other end is connected to one end of the resistor R60; one end of the capacitor C26 is connected to the other end of the resistor R60, and the other end is connected to the other end of the inductor L2;

[0042] After the capacitor C28 and the capacitor C29 are connected in parallel, one end is connected to pin 1 of the digital isolation chip U4 and the single-chip microcomputer, and the other end is grounded; after the capacitor C34 and the capacitor C35 are connected in parallel, one end is connected to pin 7 of the digital isolation chip U4, and the other end is grounded; the input end of the diode D4 is connected to the single-chip microcomputer, and the output end is connected to pin 6 of the digital isolation chip U4; pins 2, 3, 4, and 5 of the digital isolation chip U4 are all connected to the single-chip microcomputer.

[0043] The thermocouple is connected to T+ and T- of the sampling module. T+ and T- pull up 20MΩ resistors to 3.3V and pull down 20MΩ resistors to ground respectively. When T+ and T- inputs are disconnected, 3.3V is introduced into the input of the analog-to-digital conversion chip U5. The analog-to-digital conversion chip U5 samples the full bias and can identify the input disconnection. When the input signal is normally connected, the bias current generated by the 20MΩ bias resistor and 3.3V can be ignored. There is a first-order filter between the input signal and the input of the analog-to-digital conversion chip U5, which can reduce common-mode and differential-mode noise components, and also provides filtering, biasing, and overvoltage protection, and places the thermocouple in the middle of the power supply and ground. When the appropriate value is selected, the reliability of the input can be greatly improved, protecting it from electrostatic discharge (ESD) and long-term overvoltage conditions.

[0044] The number of the sampling modules is 16.

[0045] The number of the thermocouples is 16.

[0046] The RS485 communication chip U2 is of model TPT75176, which has ±15kV ESD protection, provides a differential output voltage of at least 2.1V under 5V power supply conditions, has a larger output voltage and a higher data rate, and provides a wide temperature range in industrial and extended industrial (-40°C to +125°C); if the host computer wants to obtain the temperature, it needs to send a command to the microcontroller through the RS485 communication module. After receiving the command, the microcontroller uploads the temperature collected by the 16-channel acquisition module to the host computer.

[0047] The model of the single chip microcomputer is STM32F429, which is a high-performance microcontroller based on the Cortex-M4 core, with a main frequency of up to 180MHz, supporting hardware DSP instruction set and floating point unit FPU. The internal 12-bit ADC is an analog-to-digital converter using successive approximation method, which can convert analog signals from 16 external channels.

[0048] The model of the analog-to-digital conversion chip U5 is ADS1118.

[0049] The model of the digital isolation chip U4 is NS IP8841W1.

[0050] Working principle of the present invention:

[0051] The thermocouple is contacted with a lithium battery and connected to an acquisition module in a two-wire form. The acquisition module uses a first-order filter to filter the temperature signal input by the thermocouple, and then transmits the filtered temperature signal to the analog-to-digital conversion chip U5. After the analog-to-digital conversion chip U5 performs analog-to-digital conversion on the temperature signal, it is output to the single-chip microcomputer through the digital isolation chip U4. The single-chip microcomputer converts the temperature signal into a temperature value based on a graduation table of different types of thermocouples and stores it in RAM. The host computer obtains the temperature value through the RS485 communication module.

[0052] In summary, the advantages of the present invention are:

[0053] By setting up an RS485 communication module, a single-chip microcomputer, a sampling module and a thermocouple; one end of the single-chip microcomputer is connected to the RS485 communication module, and the other end is connected to each sampling module; each thermocouple is connected to a sampling module respectively; since the resistor R53, resistor R57, resistor R62, resistor R63, capacitor C30, capacitor C31 and capacitor C36 of the sampling module constitute a first-order filter to filter the temperature signal input by the thermocouple, the interference is isolated by the digital isolation chip U4 of the sampling module, and the cold end of the thermocouple is compensated in combination with the temperature sensor provided by the analog-to-digital conversion chip U5 of the sampling module, thereby greatly improving the accuracy of lithium battery temperature acquisition; by setting the model of the analog-to-digital conversion chip U5 to ADS1118, it supports 16-channel temperature signal acquisition, and each channel has an open circuit detection function, which eliminates the hidden dangers caused by line sequence errors, thereby greatly improving the reliability of lithium battery temperature acquisition.

[0054] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A lithium battery temperature acquisition device based on thermocouple, characterized in that: It includes an RS485 communication module, a single chip microcomputer, a plurality of sampling modules and a plurality of thermocouples; One end of the single chip microcomputer is connected to the RS485 communication module, and the other end is connected to each sampling module; each of the thermocouples is connected to a sampling module respectively; The RS485 communication module includes an RS485 communication chip U2, a resistor R33, a resistor R34, a resistor R35, a resistor R37, a resistor R38, a resistor R39, a resistor R40, a resistor R41, a resistor R42, a capacitor C10, a diode clamp circuit D3 and a wiring terminal J4; Pin 1 of the RS485 communication chip U2 is connected to one end of a resistor R35, pins 2 and 3 are connected to one end of a resistor R37, pin 4 is connected to one end of a resistor R40, pin 6 is connected to one end of a resistor R39 and a resistor R41, pin 7 is connected to one end of a resistor R34 and a resistor R38, and pin 8 is connected to one end of a capacitor C10; The other end of the resistor R35 is connected to the single chip microcomputer; The other end of the resistor R37 is connected to the resistor R33 and the single chip microcomputer; the other end of the resistor R40 is connected to the resistor R42 and the single chip microcomputer; One end of the diode clamp circuit D3 is connected to the other end of the resistor R38 and the pin 1 of the connection terminal J4, and the other end is connected to the other end of the resistor R39 and the pin 2 of the connection terminal J4.

2. A lithium battery temperature acquisition device based on a thermocouple as claimed in claim 1, characterized in that: The sampling module includes an analog-to-digital conversion chip U5, a digital isolation chip U4, a resistor R50, a resistor R53, a resistor R54, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R62, a resistor R63, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28, a capacitor C29, a capacitor C30, a capacitor C31, a capacitor C33, a capacitor C34, a capacitor C35, a capacitor C36, a clamping diode D6, a diode D4 and an inductor L2; One end of the resistor R57 is connected to the resistor R53 and the positive electrode of the thermocouple, and the other end is connected to the capacitor C30, one end of the capacitor C31 and the pin 4 of the analog-to-digital conversion chip U5; one end of the resistor R62 is connected to the resistor R63 and the negative electrode of the thermocouple, and the other end is connected to the capacitor C36, the other end of the capacitor C31 and the pin 5 of the analog-to-digital conversion chip U5; after the capacitor C33 is connected in parallel with the clamping diode D6, one end is connected to the pin 8 of the analog-to-digital conversion chip U5, and the other end is connected to the pins 6 and 7 of the analog-to-digital conversion chip U5; One end of the resistor R50 is connected to pin 10 of the analog-to-digital conversion chip U5, and the other end is connected to pin 14 of the digital isolation chip U4; one end of the resistor R59 is connected to pin 9 of the analog-to-digital conversion chip U5, and the other end is connected to pin 11 of the digital isolation chip U4; one end of the resistor R54 is connected to pin 1 of the analog-to-digital conversion chip U5, and the other end is connected to pin 13 of the digital isolation chip U4; one end of the resistor R58 is connected to pin 2 of the analog-to-digital conversion chip U5, and the other end is connected to pin 12 of the digital isolation chip U4; After the capacitor C25 and the capacitor C27 are connected in parallel, one end of the capacitor C25 is connected to one end of the inductor L2 and the pin 16 of the digital isolation chip U4, and the other end is connected to one end of the resistor R60; one end of the capacitor C26 is connected to the other end of the resistor R60, and the other end is connected to the other end of the inductor L2; After the capacitor C28 and the capacitor C29 are connected in parallel, one end is connected to pin 1 of the digital isolation chip U4 and the single-chip microcomputer, and the other end is grounded; after the capacitor C34 and the capacitor C35 are connected in parallel, one end is connected to pin 7 of the digital isolation chip U4, and the other end is grounded; the input end of the diode D4 is connected to the single-chip microcomputer, and the output end is connected to pin 6 of the digital isolation chip U4; pins 2, 3, 4, and 5 of the digital isolation chip U4 are all connected to the single-chip microcomputer.

3. A lithium battery temperature acquisition device based on thermocouple as claimed in claim 1, characterized in that: The number of the sampling modules is 16.

4. A lithium battery temperature acquisition device based on a thermocouple as claimed in claim 1, characterized in that: The number of the thermocouples is 16.

5. A lithium battery temperature acquisition device based on thermocouple as claimed in claim 1, characterized in that: The model of the RS485 communication chip U2 is TPT75176.

6. A lithium battery temperature acquisition device based on thermocouple according to claim 1, characterized in that: The model of the single chip microcomputer is STM32F429.

7. A lithium battery temperature acquisition device based on a thermocouple as claimed in claim 2, characterized in that: The model of the analog-to-digital conversion chip U5 is ADS1118.

8. A lithium battery temperature acquisition device based on a thermocouple as claimed in claim 2, characterized in that: The model of the digital isolation chip U4 is NSIP8841W1.

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