Short-circuit protection system of battery pack

Abstract

The utility model discloses a short-circuit protection system of a battery pack, and belongs to the technical field of short-circuit protection of battery packs. The first end of the battery cell is connected with the positive electrode end of the battery pack; the first end of the shunt is connected with the second end of the battery cell; the input end of the switching circuit is connected with the second end of the shunt; the fuse is connected between the output end of the switching circuit and the negative electrode end of the battery pack; the acquisition part is connected between the battery cell and the control part, and the acquisition part is also connected with the first end and the second end of the shunt; and the driving circuit is connected between the switching circuit and the acquisition part. The technical scheme has the beneficial effects that through double short-circuit protection measures of the field-effect tube and the fuse, the field-effect tube performs short-circuit protection prior to the fuse, so that safety protection can be performed under the condition that the fuse is not triggered to fuse, the safety level of the battery pack is improved, and the after-sales maintenance cost and time are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of short - circuit protection of battery packs, in particular to a short - circuit protection system for a battery pack. Background Art

[0002] Regarding the short - circuit fault safety protection problem of new - energy battery packs, generally, a fuse of a certain specification needs to be connected in series in the high - voltage circuit for passive protection. For a battery pack without an MSD (Manual Service Device), after the short - circuit protection takes effect, the battery pack needs to be disassembled and repaired, and the failed fuse needs to be replaced.

[0003] In the prior art, the mainstream short - circuit protection of battery packs is to place a fuse in the high - voltage circuit of the battery pack. When a short - circuit occurs, the fuse melts to play a protective role, and the fuse is integrated with the MSD. However, due to cost limitations, the fuse of the battery pack of low - speed vehicles is placed inside the battery pack. After a short - circuit occurs and the fuse melts, the problem of disassembling the battery pack for repair will be faced, with long after - sales maintenance time and high cost. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a short - circuit protection system for a battery pack to solve the above - mentioned technical problems;

[0005] A short - circuit protection system for a battery pack includes:

[0006] A battery cell, the first end of the battery cell is connected to the positive terminal of the battery pack;

[0007] A shunt, the first end of the shunt is connected to the second end of the battery cell;

[0008] A switching circuit, the input end of the switching circuit is connected to the second end of the shunt;

[0009] A fuse, connected between the output end of the switching circuit and the negative terminal of the battery pack;

[0010] An acquisition unit, connected between the battery cell and the control unit, and the acquisition unit is also connected to the first end and the second end of the shunt;

[0011] A drive circuit, connected between the switching circuit and the acquisition unit.

[0012] Preferably, the switching circuit includes:

[0013] A charging switch tube, the drain of the charging switch tube is connected to the second end of the shunt, and the gate of the charging switch tube is connected to the drive circuit;

[0014] A discharge switch tube, the drain of the discharge switch tube is connected to the source of the charging switch tube, the source of the discharge switch tube is connected to the fuse, and the gate of the discharge switch tube is connected to the drive circuit;

[0015] A pre-charging switch tube, the drain of the pre-charging switch tube is connected to the source of the charging switch tube, and the gate of the pre-charging switch tube is connected to the drive circuit;

[0016] A pre-charge resistor, the first end of the pre-charge resistor is connected to the source of the pre-charging switch tube, and the second end of the pre-charge resistor is connected to the fuse.

[0017] Preferably, the charging switch tube, the discharge switch tube, and the pre-charging switch tube are all field effect transistors.

[0018] Preferably, the control unit is a single-chip microcomputer, the shunt is a precision resistor, and the acquisition unit is an analog front end.

[0019] Preferably, the turn-off times of the charging switch tube, the discharge switch tube, and the pre-charging switch tube are in the order of microseconds.

[0020] Preferably, the fusing time of the fuse is in the order of milliseconds.

[0021] Preferably, when the battery pack is short-circuited, the switch circuit is turned off or both the switch circuit and the fuse are disconnected.

[0022] Preferably, when the battery pack is short-circuited, the turn-off action of the switch circuit takes precedence over the fusing action of the fuse.

[0023] Preferably, when the battery pack is short-circuited, the current value between the drain and the source of the switch circuit is greater than a set threshold.

[0024] Preferably, it further includes a conversion unit for automatically recovering from the protection mode to the working mode, and the conversion unit is connected to the acquisition unit.

[0025] The beneficial effects of the present invention are: through the double short-circuit protection measures of the field effect transistor and the fuse, the field effect transistor takes precedence over the fuse for short-circuit protection, and safety protection can be carried out without triggering the fusing of the fuse, improving the safety level of the battery pack and reducing the after-sales maintenance cost and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the short-circuit protection system of the battery pack of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0028] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0029] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but it is not limited to the present invention.

[0030] A short-circuit protection system for a battery pack, as Figure 1 shown, includes,

[0031] Cell A, the first end of Cell A is connected to the positive terminal P+ of the battery pack;

[0032] Shunt resistor R1, the first end of shunt resistor R1 is connected to the second end of Cell A;

[0033] Switch circuit Q, the input terminal of switch circuit Q is connected to the second end of shunt resistor R1;

[0034] Fuse F, connected between the output terminal of switch circuit Q and the negative terminal P- of the battery pack;

[0035] Acquisition unit S, connected between Cell A and control unit C, and acquisition unit S is also connected to the first end and the second end of shunt resistor R1;

[0036] Driver circuit D, connected between switch circuit Q and acquisition unit S.

[0037] Specifically, the present invention provides a short-circuit protection system for a battery pack, which uses the switch circuit Q of the BMS (Battery Management System) in series with the fuse F to achieve double short-circuit protection, improve the safety level of the battery pack, and can perform safety protection without triggering the fuse F to blow, reducing after-sales maintenance costs and time.

[0038] More specifically, the acquisition unit S acquires the high-voltage loop current value through the shunt resistor R1. If a short circuit occurs externally, the current in the high-voltage loop will rise instantaneously. At this time, the acquisition unit S detects abnormal current, and when the current exceeds the set threshold, the acquisition unit S will turn off the drive of the switch circuit Q. Thus, the main circuit can be quickly cut off to avoid damage to electrical components caused by external short circuits. The response speed of the switch circuit Q to cut off is much faster than that of the fuse F. While achieving double protection, it can also reduce after-sales maintenance costs.

[0039] In a preferred embodiment, the switching circuit Q includes,

[0040] A charging switch transistor Q1, the drain of the charging switch transistor Q1 is connected to the second end of the shunt resistor R1, and the gate of the charging switch transistor Q1 is connected to the driving circuit D;

[0041] A discharging switch transistor Q2, the drain of the discharging switch transistor Q2 is connected to the source of the charging switch transistor Q1, the source of the discharging switch transistor Q2 is connected to the fuse F, and the gate of the discharging switch transistor Q2 is connected to the driving circuit D;

[0042] A pre-charging switch transistor Q3, the drain of the pre-charging switch transistor Q3 is connected to the source of the charging switch transistor Q1, and the gate of the pre-charging switch transistor Q3 is connected to the driving circuit D;

[0043] A pre-charging resistor R2, the first end of the pre-charging resistor R2 is connected to the source of the pre-charging switch transistor Q3, and the second end of the pre-charging resistor R2 is connected to the fuse F.

[0044] In a preferred embodiment, the charging switch transistor Q1, the discharging switch transistor Q2, and the pre-charging switch transistor Q3 are all field effect transistors.

[0045] Specifically, the field effect transistor has a low on-resistance and fast switching characteristics, which can effectively reduce power loss. The use of the charging switch transistor Q1, the discharging switch transistor Q2, and the pre-charging switch transistor Q3 can achieve efficient energy conversion during the charging and discharging processes, improving the energy utilization rate of the system.

[0046] Further specifically, the field effect transistor has high stability and strong reliability, and can operate normally under different working environments and current conditions. It helps to improve the stability of the entire battery management system, reducing the failure rate and maintenance cost.

[0047] In a preferred embodiment, the control unit C is a single-chip microcomputer, the shunt resistor R1 is a precision resistor, and the acquisition unit S is an analog front end.

[0048] Specifically, as a single-chip microcomputer, the control unit C monitors and evaluates the state of the battery in real time based on the data obtained through the acquisition circuit S, and controls the operation of the switching circuit Q according to the preset algorithms and logic. The presence of the control unit C enables the battery management system to intelligently manage the charging and discharging processes of the battery, optimizing the service life and safety of the battery.

[0049] Further specifically, the precision resistor can accurately shunt the current in the circuit, ensuring a high accuracy of the collected current value.

[0050] More specifically, the analog front end (AFE) serves as the acquisition unit S, which can receive and process the current information obtained by precision resistor shunting, monitor whether the current value exceeds the set threshold, and thus feed back to the control system in real time. The AFE collects the high-voltage loop current value through a precision resistor (shunt resistor R1). If a short circuit occurs externally, the current in the high-voltage loop will instantaneously rise to a very high level. At this time, the AFE detects abnormal current and the current exceeds the set threshold, and the AFE will turn off the drives of the charging MOS (field effect transistor) and the discharging MOS. Thus, the main circuit can be quickly cut off to avoid damage to electrical components caused by external short circuits. The reaction speed of MOS cut-off is much faster than that of the fuse F. While achieving dual protection, it can also reduce after-sales maintenance costs.

[0051] In a preferred embodiment, the turn-off times of the charging switch transistor Q1, the discharging switch transistor Q2, and the pre-charging switch transistor Q3 are in the microsecond range.

[0052] Specifically, the turn-off time in the microsecond range means that the switch transistor can switch from the on state to the off state in an extremely short time. This enables the circuit to quickly adjust and control the flow of current, effectively managing the battery charging and discharging process.

[0053] More specifically, in the BMS, the turn-off times of the charging switch transistor Q1, the discharging switch transistor Q2, and the pre-charging switch transistor Q3 in the microsecond range can prevent damage to the battery caused by overcurrent, over-discharge, or other abnormal conditions. By quickly cutting off the current, battery overload or over-discharge is avoided, extending the battery life and improving safety.

[0054] Even more specifically, the fast-response switch transistors contribute to optimizing the efficiency and control of battery charging and discharging, ensuring that the battery can operate in the best state during the charging and discharging processes, while reducing energy loss and heat loss. It enhances the precise current control ability of the battery management system, thereby improving the stability and reliability of the entire system.

[0055] In a preferred embodiment, the fusing time of the fuse F is in the millisecond range.

[0056] Specifically, the fuse F can quickly fuse and cut off the circuit when detecting an overload current or a fault current. The fusing time in the millisecond range can quickly respond to the situation where the current exceeds the rated value, thereby preventing components or equipment in the circuit from being damaged due to overcurrent.

[0057] More specifically, the fast fusing time of the fuse F effectively protects various components in electronic devices and circuits, such as power supplies, motors, electronic devices, etc., from the impact of overcurrent or short circuits, avoiding the risk of equipment damage or fire.

[0058] More specifically, timely fusing can prevent large currents from passing through equipment and circuits, reducing the likelihood of equipment damage. This not only reduces the equipment repair cost but also decreases the downtime and production losses caused by circuit problems.

[0059] In a preferred embodiment, when the battery pack is short-circuited, the switching circuit Q turns off or both the switching circuit Q and the fuse F are disconnected.

[0060] When the battery pack is short-circuited, the turn-off action of the switching circuit Q takes precedence over the fusing action of the fuse F.

[0061] When the battery pack is short-circuited, the current value between the drain and source of the switching circuit Q is greater than the set threshold.

[0062] Specifically, when the battery pack undergoes a short circuit, the current between the drain and source of the MOSFET (i.e., the field-effect transistor) in the BMS detection circuit will increase rapidly and exceed the rated value. When the current reaches a certain value, the BMS protects the MOSFET by turning off the drive circuit D and cuts off the main circuit to achieve short-circuit safety protection. The turn-off time of the MOSFET is at the microsecond level, which can effectively reduce the possible damage during the short circuit and ensure the safety and reliability of the battery pack and surrounding electronic devices.

[0063] More specifically, generally, the fusing time of the fuse F is at the millisecond level. When a short-circuit fault occurs in the system, the MOSFET electronic components of the BMS will take precedence over the fuse F for short-circuit protection actions to avoid the fuse F from fusing.

[0064] In a preferred embodiment, it further includes a conversion unit for automatically recovering from the protection mode to the working mode, and the conversion unit is connected to the acquisition unit S.

[0065] Specifically, after the system short-circuit protection function is triggered, the conversion unit of the BMS can be restored to the normal working mode through self-recovery, achieving zero-cost conversion.

[0066] Specifically, the present utility model collects the real-time pack current value through a shunt, and the AFE acquisition chip judges the current in real time. The AFE chip can configure the current threshold. Once the AFE recognizes that the total loop current suddenly increases and exceeds the threshold, the AFE will disconnect the MOS control by itself and cut off the loop. This judgment is entirely made by the AFE acquisition and judgment, without passing through the MCU (microcontroller), and the short-circuit acquisition to action time is at the microsecond level.

[0067] In summary, the present application provides a short-circuit protection system for a battery pack, which adopts dual short-circuit protection measures, can improve the safety level of the battery pack, has low after-sales cost, and can be restored to the normal working mode at zero cost through self-recovery after successful short-circuit protection.

[0068] The above are only the preferred embodiments of the present utility model, and do not limit the implementation manners and protection scope of the present utility model accordingly. For those skilled in the art, it should be realized that all the solutions obtained by equivalent substitution and obvious changes made by using the description and illustrations of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A short circuit protection system for a battery pack, characterized in that: include, A battery cell (A), wherein a first end of the battery cell (A) is connected to a positive terminal (P+) of a battery pack; A shunt (R1), wherein a first end of the shunt (R1) is connected to a second end of the battery cell (A); a switch circuit (Q), wherein an input end of the switch circuit (Q) is connected to the second end of the shunt (R1); A fuse (F) connected between the output end of the switch circuit (Q) and the negative terminal (P-) of the battery pack; A collecting unit (S) is connected between the battery cell (A) and the control unit (C), and the collecting unit (S) is also connected to the first end and the second end of the shunt (R1); The driving circuit (D) is connected between the switch circuit (Q) and the collecting unit (S).

2. The short circuit protection system of the battery pack according to claim 1, characterized in that: The switch circuit (Q) comprises, a charging switch tube (Q1), wherein a drain of the charging switch tube (Q1) is connected to the second end of the shunt (R1), and a gate of the charging switch tube (Q1) is connected to the driving circuit (D); a discharge switch tube (Q2), wherein the drain of the discharge switch tube (Q2) is connected to the source of the charge switch tube (Q1), the source of the discharge switch tube (Q2) is connected to the fuse (F), and the gate of the discharge switch tube (Q2) is connected to the drive circuit (D); A pre-charging switch tube (Q3), wherein the drain of the pre-charging switch tube (Q3) is connected to the source of the charging switch tube (Q1), and the gate of the pre-charging switch tube (Q3) is connected to the driving circuit (D); A pre-charging resistor (R2), wherein a first end of the pre-charging resistor (R2) is connected to a source of the pre-charging switch tube (Q3), and a second end of the pre-charging resistor (R2) is connected to the fuse (F).

3. The short circuit protection system of the battery pack according to claim 2, characterized in that: The charging switch tube (Q1), the discharging switch tube (Q2) and the pre-charging switch tube (Q3) are all field effect tubes.

4. The short circuit protection system for a battery pack according to claim 1, characterized in that: The control unit (C) is a single chip microcomputer, the shunt (R1) is a precision resistor, and the acquisition unit (S) is an analog front end.

5. The short circuit protection system of the battery pack according to claim 2, characterized in that: The turn-off time of the charging switch tube (Q1), the discharging switch tube (Q2) and the pre-charging switch tube (Q3) is in the microsecond level.

6. The short circuit protection system for a battery pack according to claim 1, characterized in that: The fuse (F) has a melting time of milliseconds.

7. The short circuit protection system for a battery pack according to claim 1, characterized in that: When the battery pack is short-circuited, the switch circuit (Q) is turned off or both the switch circuit (Q) and the fuse (F) are disconnected.

8. The short circuit protection system for a battery pack according to claim 1, characterized in that: When the battery pack is short-circuited, the shut-down action of the switch circuit (Q) takes precedence over the blowing action of the fuse (F).

9. The short circuit protection system of the battery pack according to claim 1, characterized in that: When the battery pack is short-circuited, the current value between the drain and the source of the switch circuit (Q) is greater than a set threshold.

10. The short circuit protection system of the battery pack according to claim 1, characterized in that: It also includes a conversion unit for automatically restoring from the protection mode to the working mode, and the conversion unit is connected to the acquisition unit (S).

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