Charging secondary temperature protection circuit and battery management system

Abstract

The utility model discloses a charging secondary temperature protection circuit and a battery management system, and the circuit comprises a low-temperature protection voltage comparator, a first voltage dividing module, a temperature sensor, a high-temperature protection voltage comparator, and a second voltage dividing module. The second input end is connected with the output end of a temperature sensor, the output end of the temperature sensor is connected with a divider resistor in series, and the output end of the low-temperature protection voltage comparator is used for sending a low-temperature protection signal to the control end of a charging switch tube of the battery management system; the first input end of the high-temperature protection voltage comparator is connected with the voltage division output end of the second voltage division module, the second input end of the high-temperature protection voltage comparator is connected with the output end of the temperature sensor, and the output end of the high-temperature protection voltage comparator is used for sending a high-temperature protection signal to the control end of a charging switch tube of the battery management system; and the low-temperature protection voltage comparator and the high-temperature protection voltage comparator are integrated double-voltage comparators.

Description

Technical Field

[0001] The utility model relates to the field of battery protection, in particular to a charging secondary temperature protection circuit and a battery management system. Background Art

[0002] In existing technology, battery management systems typically include a primary protection chip and a secondary temperature protection module. If the primary protection chip fails (i.e., if the control signal output or temperature information sampling is abnormal), the lithium-ion battery's temperature protection function will fail, posing a risk to the battery. Therefore, a secondary charging temperature protection circuit is needed to improve the reliability of the battery management system.

[0003] Since the secondary temperature protection module primarily utilizes a dedicated temperature control switch, controlling both high and low temperatures in the battery charging circuit requires a temperature control switch (temperature control module) with both high and low temperature ranges. The operating principle of the temperature control switch is based on the changes in a temperature sensing element. When the device temperature exceeds the set value, the thermistor inside the temperature control switch changes, triggering the switch to cut off power and protect the device. However, the shortcomings of existing secondary temperature protection modules include their large size, low accuracy, high cost, and difficulty adjusting temperature control parameters. Utility Model Content

[0004] The embodiments of the present invention provide a charging secondary temperature protection circuit and a battery management system to solve the problems of large size and high cost of traditional secondary temperature protection modules.

[0005] In one embodiment, a secondary charging temperature protection circuit is provided, the secondary charging temperature protection circuit comprising:

[0006] A low-temperature protection voltage comparator, a first voltage divider module, a temperature sensor, a high-temperature protection voltage comparator, and a second voltage divider module, wherein the first input of the low-temperature protection voltage comparator is connected to the voltage divider output of the first voltage divider module, the second input of the low-temperature protection voltage comparator is connected to the output of the temperature sensor, the output of the temperature sensor is connected in series with a voltage divider resistor, and the temperature sensor is used to detect the temperature of the battery; the output of the low-temperature protection voltage comparator is used to send a low-temperature protection signal to the control terminal of the charging switch tube of the battery management system;

[0007] The first input end of the high-temperature protection voltage comparator is connected to the voltage divider output end of the second voltage divider module, the second input end of the high-temperature protection voltage comparator is connected to the output end of the temperature sensor, and the output end of the high-temperature protection voltage comparator is used to send a high-temperature protection signal to the control end of the charging switch tube of the battery management system; the low-temperature protection voltage comparator and the high-temperature protection voltage comparator are integrated dual voltage comparators.

[0008] In one embodiment, the second input terminal of the low-temperature protection voltage comparator is connected to the output terminal of the low-temperature protection voltage comparator via a first feedback resistor and a first diode.

[0009] In one embodiment, the first input terminal of the high temperature protection voltage comparator is connected to the output terminal of the high temperature protection voltage comparator via a second feedback resistor.

[0010] In one embodiment, the output end of the low temperature protection voltage comparator is connected to the control end of the charging switch tube through a second diode and a current limiting resistor.

[0011] In one embodiment, the output terminal of the high temperature protection voltage comparator is connected to the control terminal of the charging switch tube through a third diode and a current limiting resistor.

[0012] In one embodiment, the temperature sensor is a strip-line thermistor sensor, and the strip-line thermistor sensor is attached to the surface of the battery cell.

[0013] In one embodiment, the first voltage divider module includes a first voltage divider resistor and a second voltage divider resistor, the first voltage divider resistor and the second voltage divider resistor are connected in series, and the series end of the first voltage divider resistor and the second voltage divider resistor serves as the voltage divider output end of the first voltage divider module.

[0014] In one embodiment, the second voltage divider module includes a third voltage divider resistor and a fourth voltage divider resistor, the third voltage divider resistor and the fourth voltage divider resistor are connected in series, and the series end of the third voltage divider resistor and the fourth voltage divider resistor serves as the voltage divider output end of the second voltage divider module.

[0015] In one embodiment, a first voltage-stabilizing capacitor is connected in parallel to both ends of the second voltage-dividing resistor, and a second voltage-stabilizing capacitor is connected in parallel to both ends of the fourth voltage-dividing resistor.

[0016] In one embodiment, a battery management system is provided, in which the charging secondary temperature protection circuit is provided.

[0017] The above-mentioned charging secondary temperature protection circuit and battery management system, by setting the low-temperature protection voltage comparator and the high-temperature protection voltage comparator into an integrated dual voltage comparator, is used to detect and compare whether the battery temperature is higher than, lower than, or between a preset temperature range, thereby realizing secondary temperature protection of the battery. The circuit is small in size and low in cost. It replaces the traditional charging secondary temperature protection implemented by using a temperature-controlled switch, so that the circuit components can be placed on the protection circuit module (PCM) of the battery management system, without occupying other battery space, and has high precision and low price. The temperature control parameters can be achieved by adjusting the voltage divider resistor, which is flexible and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 This is a circuit diagram of a secondary charging temperature protection circuit in an embodiment of the present invention.

[0020] Explanation of symbols:

[0021] 10. First voltage divider module; 20. Second voltage divider module. DETAILED DESCRIPTION

[0022] The following will be combined with the 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 embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] It should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0024] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part.

[0025] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the drawings is flipped, then the elements or features described as "under" or "beneath" or "beneath" the other elements will be oriented as "over" the other elements or features. Thus, the exemplary terms "under" and "under" may include both the upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0026] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0027] In order to fully understand the present invention, the following description will provide detailed structures and steps to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0028] In one embodiment, if Figure 1 As shown, a secondary charging temperature protection circuit is provided, and the secondary charging temperature protection circuit includes:

[0029] A low-temperature protection voltage comparator U1A, a first voltage divider module 10, a temperature sensor NTC1, a high-temperature protection voltage comparator U1B, and a second voltage divider module 20, wherein the first input end of the low-temperature protection voltage comparator U1A is connected to the voltage divider output end of the first voltage divider module 10, and the second input end of the low-temperature protection voltage comparator U1A is connected to the output end of the temperature sensor NTC1. The output end of the temperature sensor NTC1 is connected in series with a voltage divider resistor. The temperature sensor NTC1 is used to detect the temperature of the battery; the output end of the low-temperature protection voltage comparator U1A is used to send a low-temperature protection signal to the control end of the charging switch tube Q2 of the battery management system;

[0030] The first input of the high-temperature protection voltage comparator U1B is connected to the voltage-dividing output of the second voltage-dividing module 20. The second input of the high-temperature protection voltage comparator U1B is connected to the output of the temperature sensor NTC1. The output of the high-temperature protection voltage comparator U1B is used to send a high-temperature protection signal to the control terminal of the charging switch Q2 of the battery management system. The low-temperature protection voltage comparator U1A and the high-temperature protection voltage comparator U1B are integrated dual voltage comparators. Optionally, the model of the dual voltage comparator can be LM393.

[0031] Among them, the voltage dividing value of the first voltage dividing module 10 is adjusted so that the voltage dividing value of the first voltage dividing module 10 is equal to the low temperature protection voltage value collected by the temperature sensor NTC1; similarly, the voltage dividing value of the second voltage dividing module 20 is adjusted so that the voltage dividing value of the second voltage dividing module 20 is equal to the high temperature protection voltage value collected by the temperature sensor NTC1.

[0032] The working principle of the above charging secondary temperature protection circuit is as follows:

[0033] When the battery temperature detected by temperature sensor NTC1 is within a preset temperature range, because the voltage-dividing value of the voltage-dividing resistor and temperature sensor NTC1 is less than the voltage-dividing value of the first voltage-dividing module 10, the output terminal of low-temperature protection voltage comparator U1A outputs a low-level signal, which is used to send an invalid low-temperature protection signal to the control terminal of the battery management system's charging switch Q2, thereby controlling the charging switch Q2 to be non-conductive. Similarly, because the voltage-dividing value of the voltage-dividing resistor and temperature sensor NTC1 is greater than the voltage-dividing value of the second voltage-dividing module 20, the output terminal of high-temperature protection voltage comparator U1B outputs a low-level signal, which is used to send an invalid high-temperature protection signal to the control terminal of the battery management system's charging switch Q2, thereby controlling the charging switch Q2 to be non-conductive.

[0034] When the battery temperature detected by the temperature sensor NTC1 is lower than the preset temperature range, since the voltage divider value of the voltage divider resistor and the temperature sensor NTC1 is higher than the voltage divider value of the first voltage divider module 10, the output end of the low temperature protection voltage comparator U1A outputs a high-level signal, which is used to send an effective low temperature protection signal to the control end of the charging switch tube Q2 of the battery management system to control the charging switch tube Q2 to turn on.

[0035] Alternatively, when the battery temperature detected by the temperature sensor NTC1 is greater than a preset temperature range, since the voltage divider value of the voltage divider resistor and the temperature sensor NTC1 is less than the voltage divider value of the second voltage divider module 20, the output end of the high-temperature protection voltage comparator U1B outputs a high-level signal, which is used to send an effective high-temperature protection signal to the control end of the charging switch tube Q2 of the battery management system to control the charging switch tube Q2 to turn on.

[0036] The charging secondary temperature protection circuit of this embodiment configures the low-temperature protection voltage comparator U1A and the high-temperature protection voltage comparator U1B into an integrated dual voltage comparator for detecting and comparing whether the battery temperature is higher, lower, or between a preset temperature range. The low-side charging switch tube (NMOS tube) in the battery management system is used to implement the charging secondary temperature protection circuit of the battery management system, replacing the traditional charging secondary temperature protection implemented by using a temperature-controlled switch. This allows the circuit components to be placed on the protection circuit module (PCM) of the battery management system, without occupying space on other batteries. The circuit has high precision and low price, and the temperature control parameters can be achieved by adjusting the voltage divider resistor, making it flexible and convenient.

[0037] In one embodiment, the second input terminal of the low-temperature protection voltage comparator U1A is connected to the output terminal of the low-temperature protection voltage comparator U1A via a first feedback resistor and a first diode.

[0038] Among them, by adding a first feedback resistor and a first diode between the second input terminal and the output terminal of the low-temperature protection voltage comparator U1A, positive feedback is introduced into the low-temperature protection voltage comparator U1A, and the temperature action hysteresis is increased (generally leaving a hysteresis of 3~7℃), avoiding oscillation of the comparator output near the action temperature, and increasing the stability of temperature protection.

[0039] In one embodiment, the first input terminal of the high temperature protection voltage comparator U1B is connected to the output terminal of the high temperature protection voltage comparator U1B via a second feedback resistor.

[0040] Among them, by adding a second feedback resistor between the first input terminal and the output terminal of the high-temperature protection voltage comparator U1B, positive feedback is introduced into the high-temperature protection voltage comparator U1B, and the temperature action hysteresis is increased (generally leaving a hysteresis of 3~7℃), avoiding oscillation of the comparator output near the action temperature, and increasing the stability of the temperature protection.

[0041] In one embodiment, the output end of the low temperature protection voltage comparator U1A is connected to the control end of the charging switch tube Q2 through a second diode and a current limiting resistor.

[0042] Among them, the anode of the second diode is connected to the output end of the low-temperature protection voltage comparator U1A, and the cathode of the second diode is connected to the control end of the charging switch tube Q2 through the current limiting resistor. The second diode plays a role in limiting the flow direction of the current, and the current limiting resistor plays a role in limiting the amplitude of the current.

[0043] In one embodiment, the output end of the high temperature protection voltage comparator U1B is connected to the control end of the charging switch tube Q2 via a third diode and a current limiting resistor.

[0044] Among them, the anode of the third diode is connected to the output end of the high-temperature protection voltage comparator U1B, and the cathode of the third diode is connected to the control end of the charging switch tube Q2 through the current limiting resistor. The third diode plays a role in limiting the flow direction of the current, and the current limiting resistor plays a role in limiting the amplitude of the current.

[0045] In one embodiment, the temperature sensor NTC1 is a strip-wire thermistor sensor, which is attached to the surface of the battery cell to sense the temperature of the battery cell.

[0046] In one embodiment, the first voltage divider module 10 includes a first voltage divider resistor R2 and a second voltage divider resistor R3, the first voltage divider resistor R2 and the second voltage divider resistor R3 are connected in series, and the series end of the first voltage divider resistor R2 and the second voltage divider resistor R3 serves as the voltage divider output end of the first voltage divider module 10.

[0047] One end of the first voltage-dividing resistor R2 is connected to the power supply +5V, the other end of the first voltage-dividing resistor R2 is connected to one end of the second voltage-dividing resistor R3, and the other end of the second voltage-dividing resistor R3 is connected to the ground.

[0048] In one embodiment, the second voltage-dividing module 20 includes a third voltage-dividing resistor R5 and a fourth voltage-dividing resistor R6, the third voltage-dividing resistor R5 and the fourth voltage-dividing resistor R6 are connected in series, and the series connection end of the third voltage-dividing resistor R5 and the fourth voltage-dividing resistor R6 serves as the voltage-dividing output end of the second voltage-dividing module 20.

[0049] One end of the third voltage-dividing resistor R5 is connected to the power supply +5V, the other end of the third voltage-dividing resistor R5 is connected to one end of the fourth voltage-dividing resistor R6, and the other end of the fourth voltage-dividing resistor R6 is connected to the ground.

[0050] In this embodiment, the two voltage comparators, the temperature sensor NTC1, and the resistors R4, R2, R3, R5, and R6 act as window comparators for the low-temperature protection portion. When the cell temperature detected by the temperature sensor NTC1 is between 0°C and 45°C, the low-temperature protection voltage comparator U1A outputs a low level because the voltage divider between the resistor R4 and the temperature sensor NTC1 is smaller than the voltage divider between the resistor R2 and the resistor R3. Similarly, the high-temperature protection voltage comparator U1B also outputs a low level because the voltage divider between the resistor R4 and the temperature sensor NTC1 is larger than the voltage divider between the resistor R5 and the resistor R6. Consequently, the driving voltage of the charging switch Q2 is low, and the charging switch Q2 is not conducting. The charging switch Q2 connected to the resistor R13 is conducting normally, and the flow of the charging current is not affected.

[0051] However, when the battery cell temperature detected by the temperature sensor NTC1 is lower than 0°C, the low-temperature protection voltage comparator U1A outputs a high level because the voltage divider value of the resistor R4 and the temperature sensor NTC1 is greater than the voltage divider value of the resistor R2 and the resistor R3; or when the battery cell temperature detected by the temperature sensor NTC1 is higher than 45°C, the high-temperature protection voltage comparator U1B outputs a high level because the voltage divider value of the resistor R4 and the temperature sensor NTC1 is less than the voltage divider value of the resistor R5 and the resistor R6; when either the low-temperature protection voltage comparator U1A or the high-temperature protection voltage comparator U1B outputs a high level, the driving voltage of the charging switch tube Q2 is high, the charging switch tube Q2 is turned on, and the driving voltage of the charging switch tube Q2 connected to the resistor R13 is pulled down, cutting off the charging current, thereby playing a protective role in terminating charging due to high temperature (higher than 45°C) or low temperature (lower than 0°C).

[0052] In this embodiment, the low and high temperature protection values ​​can be conveniently adjusted by adjusting the resistance values ​​of the voltage divider resistors R2, R3 and the voltage divider resistors R5, R6. Compared with the traditional method of using a temperature control switch, which can only change the corresponding model of the temperature control switch to change the protection temperature, the use of a comparator method is much more flexible and convenient in changing the protection temperature.

[0053] In one embodiment, a first voltage-stabilizing capacitor is connected in parallel across the two ends of the second voltage-dividing resistor R3 , and a second voltage-stabilizing capacitor is connected in parallel across the two ends of the fourth voltage-dividing resistor R6 , to achieve voltage stabilization.

[0054] In one embodiment, a battery management system is provided, in which the charging secondary temperature protection circuit is provided.

[0055] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A charging secondary temperature protection circuit, characterized in that: The charging secondary temperature protection circuit includes: A low-temperature protection voltage comparator, a first voltage divider module, a temperature sensor, a high-temperature protection voltage comparator, and a second voltage divider module, wherein the first input of the low-temperature protection voltage comparator is connected to the voltage divider output of the first voltage divider module, the second input of the low-temperature protection voltage comparator is connected to the output of the temperature sensor, the output of the temperature sensor is connected in series with a voltage divider resistor, and the temperature sensor is used to detect the temperature of the battery; the output of the low-temperature protection voltage comparator is used to send a low-temperature protection signal to the control terminal of the charging switch tube of the battery management system; The first input end of the high-temperature protection voltage comparator is connected to the voltage divider output end of the second voltage divider module, the second input end of the high-temperature protection voltage comparator is connected to the output end of the temperature sensor, and the output end of the high-temperature protection voltage comparator is used to send a high-temperature protection signal to the control end of the charging switch tube of the battery management system; the low-temperature protection voltage comparator and the high-temperature protection voltage comparator are integrated dual voltage comparators.

2. The charging secondary temperature protection circuit according to claim 1, characterized in that: The second input end of the low temperature protection voltage comparator is connected to the output end of the low temperature protection voltage comparator through a first feedback resistor and a first diode.

3. The charging secondary temperature protection circuit according to claim 2, characterized in that: The first input terminal of the high temperature protection voltage comparator is connected to the output terminal of the high temperature protection voltage comparator through a second feedback resistor.

4. The charging secondary temperature protection circuit according to claim 1 or 2, characterized in that: The output end of the low temperature protection voltage comparator is connected to the control end of the charging switch tube through a second diode and a current limiting resistor.

5. The charging secondary temperature protection circuit according to claim 1 or 3, characterized in that: The output end of the high temperature protection voltage comparator is connected to the control end of the charging switch tube through a third diode and a current limiting resistor.

6. The charging secondary temperature protection circuit according to claim 1, characterized in that: The temperature sensor is a strip-wire thermistor sensor, which is attached to the surface of the battery cell.

7. The charging secondary temperature protection circuit according to claim 1, characterized in that: The first voltage divider module includes a first voltage divider resistor and a second voltage divider resistor, the first voltage divider resistor and the second voltage divider resistor are connected in series, and the series end of the first voltage divider resistor and the second voltage divider resistor serves as the voltage divider output end of the first voltage divider module.

8. The charging secondary temperature protection circuit according to claim 7, characterized in that: The second voltage divider module includes a third voltage divider resistor and a fourth voltage divider resistor, the third voltage divider resistor and the fourth voltage divider resistor are connected in series, and the series connection end of the third voltage divider resistor and the fourth voltage divider resistor serves as the voltage divider output end of the second voltage divider module.

9. The charging secondary temperature protection circuit according to claim 8, characterized in that: A first voltage-stabilizing capacitor is connected in parallel to both ends of the second voltage-dividing resistor, and a second voltage-stabilizing capacitor is connected in parallel to both ends of the fourth voltage-dividing resistor.

10. A battery management system, characterized in that: The battery management system is provided with a charging secondary temperature protection circuit according to any one of claims 1 to 9.

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