Temperature detection circuit, battery management system and battery pack

Abstract

The embodiment of the utility model relates to the technical field of energy storage, in particular to a temperature detection circuit, a battery management system and a battery pack, the temperature detection circuit is applied to temperature detection of the battery pack, and the temperature detection circuit comprises a detection unit, a partial pressure adjusting unit and a control unit; the detection unit is arranged in the battery pack and is configured to adjust an output signal based on the detected temperature; the partial pressure adjusting unit is connected with the control unit and the detection unit and is configured to adjust the partial pressure ratio between the partial pressure adjusting unit and the detection unit based on regulation and control of the control unit; the control unit is also connected with the detection unit, and is configured to obtain the detection temperature based on the output signal and the partial pressure ratio. The temperature detection circuit provided by the embodiment of the utility model is used for improving the detection accuracy of the temperature detection circuit in a full temperature interval.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a temperature detection circuit, a battery management system, and a battery pack. Background Art

[0002] In a battery management system, for safety reasons, it is necessary to monitor the global temperature of the battery cells in the battery pack to prevent temperature consistency problems in the battery cells caused by high-rate charging and discharging, which may cause thermal runaway of the system and spontaneous combustion of the battery cells.

[0003] The current mainstream temperature acquisition solution is to use a negative temperature coefficient (NTC) resistor and a fixed resistor to divide the voltage and acquire the temperature. The voltage is acquired by the changing resistance to identify the temperature.

[0004] However, as a nonlinear resistor, the impedance change of NTC resistor in the low and high temperature ranges is not obvious. The voltage collected by the voltage divider circuit changes proportionally, resulting in a smaller resistance value change range when the temperature is high or low, and the temperature corresponding to the collected voltage value will have a large deviation. Utility Model Content

[0005] The present application provides a temperature detection circuit, a battery management system, and a battery pack to improve the accuracy of the temperature detection circuit in detecting the entire temperature range.

[0006] To solve the above problems, in a first aspect, the present application provides a temperature detection circuit, which is applied to detect the temperature of a battery pack and is characterized by comprising: a detection unit, a voltage division adjustment unit and a control unit;

[0007] The detection unit is disposed inside the battery pack and is configured to adjust an output signal based on the detected temperature;

[0008] The voltage division regulating unit is connected to the control unit and the detection unit, and is configured to adjust the voltage division ratio between the control unit and the detection unit based on the control of the control unit;

[0009] The control unit is further connected to the detection unit and is configured to obtain the detected temperature based on the output signal and the partial pressure ratio.

[0010] Furthermore, in the temperature detection circuit provided in the present application, the detection unit includes a plurality of detection sites, and the output signal includes a plurality of sub-output signals;

[0011] The plurality of detection sites correspond one-to-one to the plurality of sub-output signals; and the plurality of detection sites are arranged at different positions of the battery cells in the battery pack.

[0012] Furthermore, in the temperature detection circuit provided in the present application, the voltage division adjustment unit includes a voltage division main branch and at least one voltage division slave branch;

[0013] Wherein, one end of the voltage division main branch and the voltage division slave branch is connected to a power supply, and the other end is connected to the detection unit;

[0014] The main voltage-dividing branch includes a main voltage-dividing resistor;

[0015] Each of the voltage-dividing branches includes a voltage-dividing secondary resistor and a control switch connected in series, and the control switch is regulated based on the control unit.

[0016] Furthermore, in the temperature detection circuit provided in the present application, the resistance values of the voltage-dividing primary resistor and the voltage-dividing secondary resistor in each of the voltage-dividing secondary branches are different.

[0017] Furthermore, in the temperature detection circuit provided in the present application, the detection unit includes a first potential output terminal and a second potential output terminal, the first potential output terminal is connected to the control unit through a first wire, and the second potential output terminal is connected to the control unit through a second wire, and the control unit obtains the output signal based on the voltage difference between the first potential output terminal and the second potential output terminal.

[0018] Furthermore, in the temperature detection circuit provided in the present application, the circuit further includes:

[0019] a filter resistor, a first end of which is connected to the first potential output end, and a second end of which is connected to the detection unit;

[0020] a first capacitor, a first electrode plate connected to the first end of the filter resistor, and a second electrode plate connected to the second potential output end;

[0021] The second capacitor has a first electrode plate connected to the second end of the filter resistor, and a second electrode plate connected to the second potential output end.

[0022] Furthermore, in the temperature detection circuit provided in the present application, the second potential output terminal is grounded.

[0023] Furthermore, in the temperature detection circuit provided in the present application, the detection unit is provided based on a temperature sensor.

[0024] In a second aspect, the present application also provides a battery management system, comprising the temperature detection circuit provided in the first aspect above, the temperature detection circuit being used to obtain the temperature of the battery pack.

[0025] In a third aspect, the present application also provides a battery pack, comprising the temperature detection circuit provided in the first aspect above, or comprising the battery management system provided in the second aspect above.

[0026] The temperature detection circuit provided in the embodiment of the present application adjusts the temperature ratio of the voltage divider adjustment unit according to different temperature ranges, so that the resistance change of the detection unit can be easily identified as the temperature changes in the entire temperature range, thereby improving the accuracy of the detection unit in temperature detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 A schematic diagram of the structure of a temperature detection circuit provided in an embodiment of the present application;

[0029] Figure 2 This is a schematic diagram of the specific structure of the temperature detection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0032] It should also be understood that the terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should be further understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0034] In addition, in this application, unless otherwise clearly specified or limited in the embodiments, the terms "installed", "connected", "connected" and "fixed" appearing in the embodiments should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integrated connection. It can also be a mechanical connection, an electrical connection, etc.; of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements, or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood based on the specific implementation.

[0035] In related technologies, temperature acquisition solutions employ negative temperature coefficient (NTC) devices arranged in the battery pack's cell area, based on the number of cells. Using the varying NTC impedance, a voltage divider circuit is designed to collect voltage and identify temperature. Specifically, a pull-up resistor is used to create a voltage divider with the NTC. As the temperature changes, the NTC resistance changes accordingly, capturing the real-time resistance value and converting it into temperature.

[0036] However, as a nonlinear resistor, the impedance change of NTC resistor in the low temperature range and high temperature range is not obvious, while the voltage acquisition is proportional. As a result, when the temperature is high (for example, greater than 80°C) or low (for example, below -20°C), the resistance value change range is small, and the temperature corresponding to the collected voltage value will have a large deviation, and the accuracy is poor in the high and low temperature range.

[0037] In order to facilitate those skilled in the art to better understand the technical solution provided by the embodiment of the present application, the temperature detection circuit provided by the embodiment of the present application is introduced below with reference to the accompanying drawings.

[0038] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the temperature detection circuit provided in this embodiment. Figure 1 As shown, the temperature detection circuit 100 provided in this embodiment is used to detect the temperature of a battery pack, and includes: a detection unit 101 , a voltage division adjustment unit 102 and a control unit 103 .

[0039] Detection unit 101 is disposed within the battery pack and is configured to adjust an output signal based on the detected temperature. Specifically, detection unit 101 is based on a temperature sensor; the temperature sensor is based on a negative temperature coefficient (NTC) device or a positive temperature coefficient device. The temperature sensor uses a varying impedance to divide the voltage with voltage divider adjustment unit 102 to obtain an output signal that varies with temperature.

[0040] It should be noted that the subsequent description of this embodiment uses the detection unit 101 composed of a negative temperature coefficient (NTC) device as an example for illustration, which does not constitute a limitation of this embodiment; in other embodiments, the detection unit composed of a positive temperature coefficient device can be used as a corresponding replacement.

[0041] The voltage-dividing regulating unit 102 is connected to the control unit 103 and the detection unit 101. The voltage-dividing regulating unit 102 is configured to adjust the voltage-dividing ratio between the voltage-dividing regulating unit 102 and the detection unit 101 based on the control of the control unit 103. Specifically, the voltage-dividing regulating unit 102 is adjusted based on the control unit 103 to change its own resistance value, thereby changing the voltage-dividing ratio between the voltage-dividing regulating unit 102 and the detection unit 101.

[0042] Assume that the resistance of the voltage divider adjustment unit 102 is R01, and the resistance of the detection unit 101 is R02, the voltage divider adjustment unit 102 and the detection unit 101 form a loop between the power supply voltage Vdd and the ground GND, and the detection unit 101 and the voltage divider adjustment unit 102 divide the power supply voltage Vdd; in the general temperature range, the resistance R02 of the detection unit 101 changes greatly with temperature, and the change in resistance of R02 at this time can cause a large change in voltage divider; based on the foregoing, it can be seen that when the temperature is high or low, the resistance R02 of the detection unit 101 changes less with temperature, and the change in resistance of R02 at this time cannot cause a large change in voltage divider; in this case, by reducing the resistance R01 of the voltage divider adjustment unit 102, the voltage divider ratio of the detection unit 101 is increased, thereby expanding the voltage divider change caused by the resistance R02 of the detection unit 101 changing with temperature, so as to improve the accuracy of temperature detection.

[0043] The control unit 103 is further connected to the detection unit 101 , and the control unit 103 is configured to obtain the detection temperature based on the output signal and the voltage division ratio.

[0044] Specifically, since the temperature detection circuit 100 provided in this embodiment involves changes in the voltage division ratio, the same temperature causes the detection unit 101 to have the same resistance value, but the output signal of the same resistance value of the detection unit 101 under different voltage division ratios is different; therefore, the control unit 103 needs to obtain the detection temperature based on the voltage division ratio and the output signal.

[0045] In one example, the control unit 103 stores the correspondence between the output signal and the detection temperature under different partial pressure ratios, obtains the partial pressure ratio and the corresponding correspondence, and then obtains the detection temperature based on the output signal by looking up the table.

[0046] Based on the above description, the temperature detection circuit 100 provided in this embodiment adjusts the temperature ratio of the voltage divider adjustment unit 102 according to different temperature ranges, so that in the entire temperature range, as the temperature changes, the resistance change of the detection unit 101 is easy to identify, thereby improving the accuracy of temperature detection by the detection unit 101.

[0047] In some embodiments, the detection unit 101 includes multiple detection sites, and the output signal includes multiple sub-output signals. The multiple detection sites correspond one-to-one to the multiple sub-output signals, and the multiple detection sites are arranged at different positions of the battery cells in the battery pack. This enables temperature detection at different positions of the battery cells, thereby obtaining the temperatures at different positions of the battery cells, so that the temperature consistency at each position in the battery pack can be maintained based on the obtained battery cell temperatures.

[0048] refer to Figure 2 , Figure 2 This is a schematic diagram of the specific structure of the temperature detection circuit provided in this embodiment. In one example, the detection unit 101 is disposed inside the battery pack to serve as an internal temperature sensor; the voltage divider adjustment unit 102 and the control unit 103 are disposed outside the battery pack to serve as an external temperature acquisition circuit to obtain the battery pack temperature.

[0049] In some embodiments, the voltage divider adjustment unit 102 includes a voltage divider main branch and at least one voltage divider slave branch; wherein, one end of the voltage divider main branch and the voltage divider slave branch is connected to a power supply to obtain a power supply voltage Vdd, and the other end is connected to the detection unit 101; the voltage divider main branch includes a voltage divider main resistor R1, and each voltage divider slave branch includes a voltage divider secondary resistor R3 and a control switch S1 in series, and the control switch S1 is regulated based on the control unit 103.

[0050] For the voltage divider regulating unit 102, in the general temperature range, the detection unit 101 is voltage-divided through the voltage divider main branch. At this time, the resistance of the voltage divider regulating unit 102 is R1; in the high temperature or low temperature range, the control switch S1 is regulated based on the control signal of the control unit 103, the control switch S1 is closed, and the voltage divider is connected from the branch. At this time, the voltage divider secondary resistor R3 and the voltage divider main resistor R1 are connected in parallel to divide the detection unit 101. At this time, the resistance of the voltage divider regulating unit 102 is R1*R2 / (R1+R2), thereby reducing the resistance of the voltage divider regulating unit 102 to adjust the voltage divider ratio of the voltage divider regulating unit 102.

[0051] In some embodiments, the control switch S1 can be formed based on a controllable transistor, which includes at least any one of the following: a thyristor, a metal-oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), a silicon carbide transistor, and a gallium nitride transistor.

[0052] It should be noted that the description of the voltage divider adjustment unit 102 in this embodiment using a voltage divider slave branch as an example does not constitute a limitation of this embodiment; those skilled in the art can set multiple voltage divider slave branches based on the same principle to adjust the resistance adjustment amount of the voltage divider adjustment unit 102, thereby adjusting the change in the voltage divider ratio of the voltage divider adjustment unit 102 to further improve the detection accuracy of the temperature detection circuit 100.

[0053] In addition, this embodiment reduces the number of control switches S1 by setting up a main voltage divider branch and a slave voltage divider branch, using the main voltage divider branch as a reference voltage divider resistor, and adjusting the resistance of the reference voltage divider resistor in parallel by the slave voltage divider branch, thereby saving the setting cost of the temperature detection circuit 100.

[0054] In some embodiments, the resistance values of the voltage divider main resistor and the voltage divider secondary resistors in each voltage divider branch are different, so as to adjust the resistance variation of the voltage divider adjustment unit 102 and further improve the detection accuracy of the temperature detection circuit 100.

[0055] Continue to refer Figure 2 , the detection unit 101 includes a first potential output terminal and a second potential output terminal, the first potential output terminal is connected to the control unit 103 through a first wire, and the second potential output terminal is connected to the control unit 103 through a second wire, that is, Figure 2 The middle sampling point is a voltage sampling point of the control unit 103 and is used to connect the control unit 103 . The control unit 103 obtains an output signal based on a voltage difference between the first potential output terminal and the second potential output terminal.

[0056] In some embodiments, the second potential output terminal or the second wire can be grounded to ensure that the potential of the second potential output terminal remains at 0. At this time, the control unit 103 can obtain the output signal only through the sampling point corresponding to the first conductive wire, so as to reduce the sampling ports of the control unit 103, thereby simplifying the circuit wiring of the temperature detection circuit 100.

[0057] In some embodiments, the control unit 103 may be an independent control CPU corresponding to the temperature detection circuit 100, or may be an MCU corresponding to the battery management system. This embodiment does not limit the specific implementation of the control unit 103. Specifically, the control unit 103 obtains the output signal of the sampling point through the analog-to-digital conversion function and obtains the real-time temperature value through the output signal. When it is recognized that the real-time temperature value is higher or lower than a specific temperature point, the control unit 103 turns on / off the corresponding control switch through the control signal to change the voltage division ratio of the voltage division adjustment unit 102. The control unit 103 then continues to obtain the output signal of the sampling point through the analog-to-digital conversion function, and obtains the real-time temperature value through the output signal and the corresponding voltage division ratio.

[0058] In some embodiments, the temperature detection circuit 100 also includes: a filter resistor R2, a first end of which is connected to the first potential output end, and a second end of which is connected to the detection unit 101; a first capacitor C1, a first electrode plate of which is connected to the first end of the filter resistor R2, and a second electrode plate of which is connected to the second potential output end; a second capacitor C2, a first electrode plate of which is connected to the second end of the filter resistor R2, and a second electrode plate of which is connected to the second potential output end.

[0059] For the first capacitor C1 and the second capacitor C2, one of them is used as an electrostatic protection capacitor and the other is used as a filter capacitor. By setting the electrostatic protection capacitor, the filter capacitor and the filter resistor R2, the detection error of the detection unit 101 can be effectively reduced, which is beneficial to improving the accuracy of the detection circuit.

[0060] It should be noted that the temperature detection circuit 100 provided in this embodiment does not constitute a limitation on the number of first capacitors C1, second capacitors C2, and filter resistors R2. In addition, in some embodiments, if the second potential output terminal and / or the second drop line are not grounded but connected to the control unit 103, a corresponding filter resistor R2 is also required on the second wire.

[0061] To sum up, the temperature detection circuit provided in this embodiment changes the resistance of the pull-up resistor by controlling the switch to connect the voltage divider resistor in parallel when the temperature is high or low, thereby increasing the voltage divider ratio of the detection unit to achieve adjustment with different temperature ranges by changing the temperature ratio of the voltage divider adjustment unit, so that in the entire temperature range, as the temperature changes, the resistance change of the detection unit is easy to identify, thereby improving the accuracy of the detection unit in temperature detection.

[0062] Another embodiment of the present application also provides a battery management system, including the temperature detection circuit 100 mentioned in the above embodiment, which is used to obtain the temperature of the battery pack to improve the accuracy of the temperature detection circuit in detection across the entire temperature range.

[0063] The Battery Management System (BMS) is used to manage secondary batteries to improve battery utilization, prevent overcharging and over-discharging, extend battery life, and monitor battery status.

[0064] Specifically, during the battery charging and discharging process, the battery management system collects the terminal voltage and temperature of each battery in the battery pack, the charge and discharge current, and the total battery pack voltage in real time to prevent overcharging or overdischarging of the batteries. Temperature collection is implemented using the temperature detection circuit 100 provided in the above-mentioned embodiment to improve temperature collection accuracy. The battery management system also provides timely battery status information, identifying problematic batteries, maintaining the reliability and efficiency of the entire battery pack, and enabling the implementation of a remaining charge estimation model.

[0065] In some embodiments, the present application also provides a battery pack, which includes the battery management system mentioned in the above embodiments, or the temperature detection circuit mentioned in the above embodiments.

[0066] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A temperature detection circuit, used for detecting the temperature of a battery pack, characterized in that: include: Detection unit, voltage division adjustment unit and control unit; The detection unit is disposed inside the battery pack and is configured to adjust an output signal based on the detected temperature; The voltage division regulating unit is connected to the control unit and the detection unit, and is configured to adjust the voltage division ratio between the control unit and the detection unit based on the control of the control unit; The control unit is further connected to the detection unit and is configured to obtain the detected temperature based on the output signal and the partial pressure ratio.

2. The temperature detection circuit according to claim 1, wherein: The detection unit includes a plurality of detection sites, and the output signal includes a plurality of sub-output signals; The plurality of detection sites correspond one-to-one to the plurality of sub-output signals; and the plurality of detection sites are arranged at different positions of the battery cells in the battery pack.

3. The temperature detection circuit according to claim 1, wherein: The voltage division regulating unit includes a voltage division main branch and at least one voltage division slave branch; Wherein, one end of the voltage division main branch and the voltage division slave branch is connected to a power supply, and the other end is connected to the detection unit; The main voltage-dividing branch includes a main voltage-dividing resistor; Each of the voltage-dividing branches includes a voltage-dividing secondary resistor and a control switch connected in series, and the control switch is regulated based on the control unit.

4. The temperature detection circuit according to claim 3, wherein: The resistance values of the voltage-dividing primary resistor and the voltage-dividing secondary resistor in each of the voltage-dividing secondary branches are different.

5. The temperature detection circuit according to claim 1, wherein: The detection unit includes a first potential output terminal and a second potential output terminal, the first potential output terminal is connected to the control unit through a first wire, and the second potential output terminal is connected to the control unit through a second wire, and the control unit obtains the output signal based on the voltage difference between the first potential output terminal and the second potential output terminal.

6. The temperature detection circuit according to claim 5, characterized in that: The circuit further comprises: a filter resistor, a first end of which is connected to the first potential output end, and a second end of which is connected to the detection unit; The first capacitor has a first electrode plate connected to the first end of the filter resistor, and the second electrode plate connected to the a second potential output terminal; The second capacitor has a first electrode plate connected to the second end of the filter resistor, and a second electrode plate connected to the second potential output end.

7. The temperature detection circuit according to claim 6, characterized in that: The second potential output terminal is grounded.

8. The temperature detection circuit according to any one of claims 1 to 7, characterized in that: The detection unit is provided based on a temperature sensor.

9. A battery management system, characterized in that: The temperature detection circuit comprises the temperature detection circuit according to any one of claims 1 to 8.

10. A battery pack, characterized in that: The temperature detection circuit comprises the temperature detection circuit according to any one of claims 1 to 8, or the battery management system according to claim 9.

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