Load detection circuit of battery management system protection board

Abstract

The utility model discloses a load detection circuit of a battery management system protection board. The load detection circuit comprises a battery pack, the battery management system protection board and a load detection circuit, the battery pack is connected with the load and the battery management system protection board to form a battery management system protection unit; the load detection circuit is connected with the load and the battery management system protection board to form a load detection unit; the battery management system protection board comprises an AFE chip, and when the battery management system protection unit triggers overcurrent or short-circuit protection, the load detection unit is conducted with the AFE chip for load detection; according to the load detection unit, the CHG pin of the AFE chip can be switched on through the load detection circuit when the circuit is in a discharge over-current protection state or a short-circuit protection state, so that the load detection function of the AFE chip is realized.

Description

Technical Field

[0001] The present application belongs to the technical field of battery management system protection, and specifically refers to a load detection circuit of a battery management system protection board. Background Art

[0002] The battery management system BMS is the link between the battery and the user. Its main purpose is to improve the utilization rate of the battery, prevent the battery from overcharging and over-discharging, extend the battery life, monitor the battery status, etc. At present, the BMS protection board of lithium batteries basically uses AFE chips to monitor various parameters of the battery and trigger protection actions. When there is a discharge overcurrent or short circuit in the circuit, the corresponding protection is triggered, and the BMS protection board of the lithium battery will turn off the discharge MOS tube. The AFE chip is designed with a CHG pin, which can be used for both charging MOS control and load detection. If this function is applied, the need to remove the load from the fault of discharge overcurrent or short circuit protection can be achieved.

[0003] However, due to the consideration of the driving capability of the AFE chip driving pin and the protection of the AFE chip, a MOS driving circuit will be added in the post-AFE chip stage. Due to the peripheral or internal structure of the driving circuit, the high level cannot be passed in reverse, resulting in that even if the load is connected, the high level cannot be transmitted to the CHG pin through the driving circuit, thereby causing the load detection function of the AFE chip to fail. Utility Model Content

[0004] In order to overcome the deficiencies of the prior art, the present application provides a load detection circuit for a battery management system protection board, which can enable the AFE chip to perform load detection during discharge overcurrent or short circuit protection.

[0005] The utility model provides a load detection circuit of a battery management system protection board, comprising: a battery pack, a battery management system protection board and a load detection circuit; the battery pack is connected to a load and the battery management system protection board to form a battery management system protection unit, and the load detection circuit is connected to a load and the battery management system protection board to form a load detection unit; the battery management system protection board comprises an AFE chip, and when the battery management system protection unit triggers overcurrent or short circuit protection, the load detection unit is connected to the AFE chip to perform load detection.

[0006] Further, the battery management system protection board further includes a charge and discharge MOS transistor and a drive circuit; one end of the charge and discharge MOS transistor is connected to the output terminal P- of the load, and the other end of the charge and discharge MOS transistor is connected to the negative electrode B- of the battery pack; the other end of the charge and discharge MOS transistor is also connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the CHG pin of the AFE chip, and the AFE chip is grounded.

[0007] Further, the drive circuit is any one of a triode drive circuit, a MOS transistor drive circuit, and a drive chip drive circuit.

[0008] Further, the output terminal P- of the load is connected to the input end of the load detection circuit, and the output end of the load detection circuit is connected to the CHG pin of the AFE chip to form a load detection unit.

[0009] Further, the load detection circuit includes a first current limiting resistor R5, a first optocoupler OP1, a first diode D4, a first capacitor C2, a second current limiting resistor R3, a second optocoupler OP2, and a second diode D3;

[0010] One end of the first current limiting resistor R5 is connected to the IO terminal of the MCU and one end of the first capacitor C2, the other end of the first capacitor C2 is grounded, the other end of the first current limiting resistor R5 is connected to the first optocoupler OP1, and the first optocoupler OP1 is connected to the first diode D4 and grounded; one end of the second current limiting resistor R3 is connected to the output terminal P- of the load, the other end of the second current limiting resistor R3 is connected to the second optocoupler OP2, the second optocoupler OP2 is connected to the first optocoupler OP1 and the second diode D3, and the second diode D3 is connected to the CHG pin of the AFE chip.

[0011] Further, when the battery management system protection board is in the shutdown state, or there is no discharge overcurrent protection state, or there is no short circuit protection state, the IO terminal of the MCU is set to be floating or pulled down, the input end of the first optocoupler OP1 cannot conduct forward, and the load detection unit is not connected to the AFE chip.

[0012] Further, when the battery management system protection board is in the discharge overcurrent protection state or the short circuit protection state, the charge and discharge MOS transistor is turned off, the IO terminal of the MCU is set to output a high level, the input end of the first optocoupler OP1 conducts, and the output end of the first optocoupler OP1 conducts to form a load detection pre-action loop.

[0013] Further, when the protection board of the battery management system is in the over-discharge current protection state or the short-circuit protection state and the load is not removed, the output terminal P- of the load outputs a high level, and forms a loop with the second current-limiting resistor R3, the input terminal of the second optocoupler OP2, the output terminal of the first optocoupler OP1, and the first diode D4; the output terminal of the second optocoupler OP2 conducts, and conducts the second diode D3, and forms a load detection loop with the CHG pin of the AFE chip.

[0014] Further, the charge and discharge MOS transistors are DMOS transistors and CMOS transistors.

[0015] The beneficial effects of the present invention are as follows:

[0016] The present invention provides a load detection circuit for a protection board of a battery management system. A load detection unit is formed by directly arranging a load detection circuit between the load of the circuit and the CHG pin of the AFE chip. When the circuit is in the over-discharge current protection state or the short-circuit protection state, the load detection unit can conduct the CHG pin of the AFE chip through the load detection circuit, realizing the load detection function of the AFE chip, solving the problem of reverse cut-off of the drive circuit, and enabling the load detection of the AFE chip to be applied. Description of the Drawings

[0017] The following, in conjunction with the drawings, through a detailed description of the specific embodiments of the present application, will make the technical solutions and other beneficial effects of the present application obvious.

[0018] Figure 1 It is a schematic structural diagram of a load detection circuit for a protection board of a battery management system provided in this embodiment.

[0019] Figure 2 It is a schematic structural diagram of a triode drive circuit provided in this embodiment.

[0020] Figure 3 It is a schematic structural diagram of a MOS transistor drive circuit provided in this embodiment.

[0021] Figure 4 It is a schematic structural diagram of a drive chip drive circuit provided in this embodiment.

[0022] Figure 5 It is a schematic structural diagram of the load detection circuit provided in this embodiment.

[0023] Figure 6 It is a schematic structural diagram of the AFE chip provided in this embodiment. Detailed Embodiments

[0024] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0025] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0026] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0027] The current battery management system protection boards all use AFE chips to monitor various battery parameters and trigger protection actions. When the discharge overcurrent or short circuit triggers the corresponding protection, the discharge MOS tube will be turned off. In addition, the AFE chip is designed with a CHG pin, which can be used for both charging MOS control and load detection. If this function is applied, the need to remove the load to relieve the fault of discharge overcurrent or short circuit protection can be achieved. However, due to the driving capability of the AFE chip drive pin and for the protection of the AFE chip, a MOS tube drive circuit will be added to the post-AFE chip stage, but the drive circuit has a reverse cutoff, resulting in the inability to pass the high level with load to CHG. As a result, the AFE chip cannot perform load detection.

[0028] This embodiment provides a load detection circuit for a battery management system protection board, such as Figure 1 As shown, it includes: a battery pack, a battery management system protection board and a load detection circuit; the battery pack is connected to the load and the battery management system protection board to form a battery management system protection unit, and the load detection circuit is connected to the load and the battery management system protection board to form a load detection unit; the battery management system protection board includes an AFE chip, and when the battery management system protection unit triggers overcurrent or short circuit protection, the load detection unit is connected to the AFE chip to perform load detection.

[0029] Specifically, Figure 1 As shown, the battery management system protection board also includes a charge-discharge MOS tube and a drive circuit; one end of the charge-discharge MOS tube is connected to the output end P- of the load, and the other end of the charge-discharge MOS tube is connected to the negative electrode B- of the battery pack; the other end of the charge-discharge MOS tube is also connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the CHG pin of the AFE chip, and the AFE chip is grounded. Among them, the charge-discharge MOS tube is a DMOS tube and a CMOS tube.

[0030] When the circuit is working properly, the battery pack, the load, and the charge and discharge MOS transistor can form a working circuit; and the battery pack, the load, and the battery management system protection board form a circuit. In the design of the battery management system protection board, a drive circuit is used for the charge and discharge MOS transistor to enhance the driving ability of the circuit. When an overcurrent discharge or short circuit occurs in the circuit, the battery management system protection board will trigger overcurrent discharge or short circuit protection, and the battery management system protection board will turn off the charge and discharge MOS transistor. At this time, the instantaneous drop of the current in the circuit will cause the power line cable to be inductive and form an induced voltage. The greater the current, the greater the induced voltage. If this voltage enters the CHG pin of the AFE chip without protection, the AFE chip will be damaged. Therefore, in the design of the drive circuit, anti-reverse peak and anti-reverse diode design are considered. Therefore, in this embodiment, the drive circuit is any one of a triode drive circuit, a MOS transistor drive circuit, and a drive chip drive circuit.

[0031] Figure 2 The structural schematic diagram of the triode drive circuit provided by this embodiment is as Figure 2 shown. The triode drive circuit includes a triode Q8, a diode D7, and a diode DS5. Among them, the base of the triode Q8 is connected to the CHG pin of the AFE chip, and the emitter and collector of the triode Q8 are respectively connected to the diode D7 and the diode DS5; the diode D7 and the diode DS5 are respectively connected to the charge and discharge MOS transistor.

[0032] Figure 3 The structural schematic diagram of the MOS transistor drive circuit provided by this embodiment is as Figure 3 shown. The MOS transistor drive circuit includes a MOS transistor NM1, a diode D8, and a diode DS6. Among them, the gate of the MOS transistor NM1 is connected to the CHG pin of the AFE chip, and the source and drain of the MOS transistor NM1 are respectively connected to the diode D8 and the diode DS6; the diode D8 and the diode DS6 are respectively connected to the charge and discharge MOS transistor.

[0033] Figure 4 The structural schematic diagram of the drive chip drive circuit provided by this embodiment is as Figure 4 shown. The drive chip drive circuit includes a drive chip U4. The 1st pin of the drive chip U4 is connected to VCC, the 2nd pin of the drive chip U4 is connected to the output terminal P- of the load, the 3rd pin of the drive chip U4 is connected to the CHG pin of the AFE chip, the 4th pin of the drive chip U4 is connected to the output terminal P- of the load, and the 5th pin of the drive chip U4 is connected to the charge and discharge MOS transistor.

[0034] Due to the reverse cut-off situation of the driving circuit, when there is an over-current discharge phenomenon or a short-circuit phenomenon in the circuit, the high level with load cannot conduct to the CHG pin of the AFE chip. Therefore, in this embodiment, a load detection circuit is added. As Figure 1 shown, the output end P- of the load is connected to the input end of the load detection circuit, and the output end of the load detection circuit is connected to the CHG pin of the AFE chip to form a load detection unit.

[0035] Figure 5 is a schematic structural diagram of the load detection circuit provided in this embodiment. As Figure 5 shown, the load detection circuit includes a first current-limiting resistor R5, a first optocoupler OP1, a first diode D4, a first capacitor C2, a second current-limiting resistor R3, a second optocoupler OP2, and a second diode D3.

[0036] Specifically, one end of the first current-limiting resistor R5 is connected to the IO end of the MCU and one end of the first capacitor C2, the other end of the first capacitor C2 is grounded, the other end of the first current-limiting resistor R5 is connected to the first optocoupler OP1, and the first optocoupler OP1 is connected to the first diode D4 and grounded. Among them, the first current-limiting resistor R5 is connected to the input end light-emitting diode of the first optocoupler OP1, the output end of the first optocoupler OP1 is connected to the positive pole of the first diode D4, and the negative pole of the first diode D4 is grounded.

[0037] One end of the second current-limiting resistor R3 is connected to the output end P- of the load, the other end of the second current-limiting resistor R3 is connected to the second optocoupler OP2, the second optocoupler OP2 is connected to the first optocoupler OP1 and the second diode D3, and the second diode D3 is connected to the CHG pin of the AFE chip. Among them, the input end light-emitting diode of the second optocoupler OP2 is connected to the second current-limiting resistor R3 and the output end of the first optocoupler OP1, the output end of the second optocoupler OP2 is connected to VCC and the positive pole of the second diode D3, and the negative pole of the second diode D3 is connected to the CHG pin of the AFE chip.

[0038] Figure 6 is a schematic structural diagram of the AFE chip provided in this embodiment. As Figure 6 shown, the CHG pin of the AFE chip BQ1 is connected to a third current-limiting resistor R4, the other end of the third current-limiting resistor R4 is connected to the source of the MOS transistor PM1, the gate of the MOS transistor PM1 is grounded, and the drain of the MOS transistor PM1 is connected to the load detection circuit.

[0039] In this embodiment, when the battery management system protection board is in the shutdown state, or there is no discharge overcurrent protection state or no short-circuit protection state, the IO port of the MCU can be set to floating or pulled down, and the input end of the first optocoupler OP1 cannot conduct forward. Therefore, the output end of the first optocoupler OP1 also does not conduct, thus preventing a loop from being formed between the output end P- of the load and the ground end GND. The load detection unit is not connected to the AFE chip, preventing the problem that the battery pack continuously discharges through the load detection circuit.

[0040] When the battery management system protection board is in the discharge overcurrent protection state or the short-circuit protection state, the charge and discharge MOS transistor is turned off. When the battery management system protection board is in the discharge overcurrent protection state or the short-circuit protection state, the IO port of the MCU is set to output a high level, and through the first current-limiting resistor R5, the high level makes the light-emitting diode at the input end of the first optocoupler OP1 conduct forward. At the same time, the output end of the first optocoupler OP1 conducts to form a pre-action loop for load detection. At this time, the function of the first diode D4 is to prevent current backflow and protect the output end of the first optocoupler OP1. At the same time, the function of the pre-action loop for load detection is to prevent the problem that the battery pack continuously discharges through the load detection circuit when the load is not removed.

[0041] When the battery management system protection board triggers the discharge overcurrent protection state or the short-circuit protection state and the load is not removed, the level of the output terminal P- of the load will be much higher than the level of the ground GND. At this time, the positive pole of the battery pack passes through the load, through the second current-limiting resistor R3, the input light-emitting diode of the second optocoupler OP2, the output terminal of the first optocoupler OP1, and the first diode D4 to reach the negative pole of the battery and form a complete loop. The output terminal of the second optocoupler OP2 conducts, and the second diode D3 is conducted, forming a load detection loop with the CHG pin of the AFE chip. Because the input light-emitting diode of the second optocoupler OP2 is forward-conducted, the output terminal of the second optocoupler OP2 conducts, and the high level of VCC passes through the input terminal of the second optocoupler OP2, the second diode D3, the MOS transistor PM1, and the third current-limiting resistor R4 to reach the CHG pin of the AFE chip BQ1. Since the CHG pin of the AFE chip BQ1 is preset to the load detection function, at this time, when the CHG pin of the AFE chip BQ1 detects a high level, it is considered that there is a load. And, in this loop, the function of the second diode D3 is to prevent level backflow. When the CHG pin of the AFE chip BQ1 does not serve as the load detection function, the CHG pin outputs a high level as a driving signal. At this time, the level signal fluctuation of this driving signal may be higher than the VECO of the second optocoupler OP2. Therefore, the second diode D3 is used to prevent the high level from flowing back to the second optocoupler OP2.

[0042] After the battery management system protection board triggers the discharge overcurrent protection state or the short-circuit protection state, if the load is removed, at this time, there is no high level at the output terminal P- of the load. Therefore, the input light-emitting diode of the second optocoupler OP2 is cut off, and the output terminal of the second optocoupler OP2 does not conduct. At this time, the CHG pin of the AFE chip BQ1 cannot detect a high level and it is considered that the load does not exist and has been removed.

[0043] The present invention provides a load detection circuit for a battery management system protection board, which directly sets up a load detection circuit between the load in the circuit and the CHG pin of the AFE chip to form a load detection unit. The load detection unit can realize that when the circuit appears in the discharge overcurrent protection state or the short-circuit protection state, the CHG pin of the AFE chip is conducted through the load detection circuit, realizing the load detection function of the AFE chip, solving the problem of reverse cut-off of the drive circuit, and enabling the load detection of the AFE chip to be applied.

[0044] Although the preferred embodiments of the embodiments of the present utility model have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present utility model. Finally, it should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.

[0045] The above has introduced in detail a load detection circuit of a battery management system protection board provided by the embodiments of the present application. Specific examples are used in this text to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A load detection circuit for a protection board of a battery management system, characterized in that, Including: a battery pack, a battery management system protection board, and a load detection circuit; The battery pack is connected to a load and the battery management system protection board to form a battery management system protection unit, and the load detection circuit is connected to the load and the battery management system protection board to form a load detection unit; the battery management system protection board includes an AFE chip. When the battery management system protection unit triggers overcurrent or short-circuit protection, the load detection unit is conducted with the AFE chip to perform load detection.

2. The load detection circuit of the battery management system protection board according to claim 1, characterized in that, The battery management system protection board further includes a charge and discharge MOS tube and a drive circuit; one end of the charge and discharge MOS tube is connected to the output end P- of the load, and the other end of the charge and discharge MOS tube is connected to the negative electrode B- of the battery pack; the other end of the charge and discharge MOS tube is also connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the CHG pin of the AFE chip, and the AFE chip is grounded.

3. The load detection circuit of the battery management system protection board according to claim 2, characterized in that, The drive circuit is any one of a triode drive circuit, a MOS tube drive circuit, and a drive chip drive circuit.

4. The load detection circuit of the battery management system protection board according to claim 2, wherein The output end P- of the load is connected to the input end of the load detection circuit, and the output end of the load detection circuit is connected to the CHG pin of the AFE chip to form a load detection unit.

5. The load detection circuit of the battery management system protection board according to claim 4, characterized in that The load detection circuit includes a first current-limiting resistor R5, a first optocoupler OP1, a first diode D4, a first capacitor C2, a second current-limiting resistor R3, a second optocoupler OP2, and a second diode D3; One end of the first current-limiting resistor R5 is connected to the IO end of the MCU and one end of the first capacitor C2, the other end of the first capacitor C2 is grounded, the other end of the first current-limiting resistor R5 is connected to the first optocoupler OP1, and the first optocoupler OP1 is connected to the first diode D4 and grounded; one end of the second current-limiting resistor R3 is connected to the output end P- of the load, the other end of the second current-limiting resistor R3 is connected to the second optocoupler OP2, the second optocoupler OP2 is connected to the first optocoupler OP1 and the second diode D3, and the second diode D3 is connected to the CHG pin of the AFE chip.

6. The load detection circuit of the battery management system protection board according to claim 5, characterized in that When the battery management system protection board is in the shutdown state, or there is no discharge overcurrent protection state, or there is no short-circuit protection state, the IO end of the MCU is set to be floating or pulled down, the input end of the first optocoupler OP1 cannot be forward-conducted, and the load detection unit is not connected to the AFE chip.

7. The load detection circuit of the battery management system protection board according to claim 5, wherein When the battery management system protection board is in the discharge overcurrent protection state or the short-circuit protection state, the charge and discharge MOS tube is turned off, the IO end of the MCU is set to output a high level, the input end of the first optocoupler OP1 is conducted, and the output end of the first optocoupler OP1 is conducted to form a load detection pre-action loop.

8. The load detection circuit of the battery management system protection board according to claim 5, wherein When the protection board of the battery management system is in the over-discharge over-current protection state or the short-circuit protection state and the load is not removed, the output terminal P- of the load outputs a high level, and forms a loop with the second current-limiting resistor R3, the input terminal of the second optocoupler OP2, the output terminal of the first optocoupler OP1, and the first diode D4; the output terminal of the second optocoupler OP2 conducts, and conducts the second diode D3, and forms a load detection loop with the CHG pin of the AFE chip.

9. The load detection circuit of the battery management system protection board according to claim 2, characterized in that, The charge and discharge MOS transistors are DMOS transistors and CMOS transistors.

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