CN111668901B

CN111668901B - Battery protection circuit, battery management system, battery device and control method thereof

Info

Publication number: CN111668901B
Application number: CN202010555943.6A
Authority: CN
Inventors: 秦友强; 焦磊明
Original assignee: Dongguan Poweramp Technology Ltd
Current assignee: Dongguan Poweramp Technology Ltd
Priority date: 2020-06-17
Filing date: 2020-06-17
Publication date: 2023-04-18
Anticipated expiration: 2040-06-17
Also published as: WO2021253848A1; CN111668901A

Abstract

The application provides a battery protection circuit, which is electrically connected between a battery cell unit and an external port to form a power supply loop and comprises a first protection unit, a second protection unit and a sensing switch unit; the first protection unit is electrically connected between the battery cell unit and the second protection unit; the sensing switch unit is arranged at a preset position of the battery cell unit and is electrically connected with the second protection unit; and under the condition that the sensing switch unit is triggered to be switched on and the first protection unit does not cut off the power supply loop, controlling the second protection unit to protect the battery cell unit. The application also provides a battery management system, a battery device and a control method thereof. The application provides battery protection circuit has security height, range of application is wide, advantage such as the cost is lower.

Description

Battery protection circuit, battery management system, battery device and control method thereof

Technical Field

The present disclosure relates to the field of battery technologies, and in particular, to a battery protection circuit, a battery management system having the battery protection circuit, a battery device having the battery protection circuit, and a control method of the battery device.

Background

At present, the lithium ion battery is used as an important energy source by people in a large range, plays an extremely important role in the fields of electronic communication, transportation and the like, and has wide application prospect. The safety of lithium ion batteries is also a non-negligible problem.

Lithium ion batteries are generally safe when used as specified, but can be potentially dangerous in the event of internal or mechanical failure. For example, when the battery is under abusive conditions, such as overcharging, compression, high temperature, or short circuiting. May result in overheating, emission of smoke and even fire and explosion. In the prior art, a lithium ion battery protection chip can monitor the charging and discharging processes and intervene when the process is possibly out of the risk of the safe working range of the battery. However, when the lithium ion battery protection chip fails, the risk early warning cannot be performed on the battery.

Disclosure of Invention

In view of the foregoing, it is desirable to provide a battery protection circuit, a battery management system having the battery protection circuit, a battery device, and a control method thereof, which can protect a cell unit.

One embodiment of the present application provides a battery protection circuit, which is electrically connected between a cell unit and an external port to form a power supply loop, and includes a first protection unit, a second protection unit, and a sensing switch unit; the first protection unit is electrically connected between the battery cell unit and the second protection unit; the sensing switch unit is arranged at a preset position of the battery cell unit and is electrically connected with the second protection unit; and controlling the second protection unit to protect the battery cell unit under the condition that the sensing switch unit is triggered to be switched on and the first protection unit does not cut off the power supply loop.

According to some embodiments of the present application, the second protection unit includes a fuse, a first resistor, and a first switch, a first end of the fuse is connected to the positive electrode of the battery cell unit, a second end of the fuse is connected to a second end of the first switch through the first resistor, and a third end of the fuse is connected to the positive electrode of the external port; the first end of the first switch is electrically connected with the sensing switch unit, the second end of the first switch is grounded, and the third end of the first switch is electrically connected with the second end of the fuse.

According to some embodiments of the present application, the sensing switch unit is a temperature switch, and if the temperature of the battery cell unit detected by the temperature switch exceeds a preset temperature, the temperature switch is triggered to be turned on, so as to trigger the first switch to be turned on to heat the first resistor, and fuse the fuse to protect the battery cell unit.

According to some embodiments of the application, the sensing switch unit is a microswitch, and if the cell unit is extruded due to thermal expansion, the microswitch is triggered to be switched on, so that the first switch is triggered to be switched on to heat the first resistor, and the fuse is fused to protect the cell unit.

According to some embodiments of the present application, the battery protection circuit further includes a third protection unit electrically connected between the cell unit and the second protection unit.

According to some embodiments of the present application, in a case that the sensing switch unit is triggered to be turned on, the first protection unit does not cut off the power supply loop, and the third protection unit does not trigger the second protection unit, the second protection unit is controlled to protect the cell unit.

An embodiment of the present application provides a battery management system, which includes the battery protection circuit as described above.

According to some embodiments of the present application, when the battery management system controls the cell unit to discharge at a preset current, if the sensing switch unit is turned on, the second protection unit is triggered to protect the cell unit.

According to some embodiments of the application, the second protection unit comprises a fuse, and a difference between a rated current of the fuse and the preset current is smaller than or equal to a current threshold.

An embodiment of the present application provides a battery device, the battery device includes a battery cell unit, the battery device further includes the battery protection circuit as described above, and the battery protection circuit is configured to protect the battery cell unit.

An embodiment of the present application provides a control method for a battery device, where the battery device includes a battery cell and a battery protection circuit electrically connected to the battery cell, the battery protection circuit is electrically connected between the battery cell and an external port to form a power supply loop, the battery protection circuit includes a first protection unit, a second protection unit, and a sensing switch unit, and the method includes:

and under the condition that the sensing switch unit is triggered to be switched on and the first protection unit does not cut off the power supply loop, controlling the second protection unit to protect the battery cell unit.

According to some embodiments of the present application, the battery protection circuit further includes a third protection unit electrically connected between the cell unit and the second protection unit, and the method further includes:

and controlling the second protection unit to protect the battery cell unit under the condition that the sensing switch unit is triggered to be switched on, the first protection unit does not cut off the power supply loop, and the third protection unit does not trigger the second protection unit.

According to some embodiments of the application, the battery device comprises a battery management system, the method further comprising:

when the battery management system controls the battery cell unit to discharge at a preset current, if the sensing switch unit is triggered to be switched on, the second protection unit is controlled to protect the battery cell unit.

The battery protection circuit and the battery management system with the same provided by the embodiment of the application set up the sensing switch unit at the preset position of the battery cell unit, and the sensing switch unit is electrically connected with the second protection unit, if the first protection unit does not trigger the second protection unit, and when the sensing switch unit is triggered to be switched on, the second protection unit is controlled to protect the battery cell unit. The battery management system can effectively avoid the electric core unit fire and explosion accidents caused by overcharge, overdischarge or discharge with the current high multiplying power close to the rated current of the fuse under the condition of single-point failure. The battery protection circuit has the advantages of high safety, wide application range, low cost and the like.

Drawings

Fig. 1 is a block diagram of a battery device according to a first preferred embodiment of the present application.

Fig. 2 is a block diagram of a battery device according to a second preferred embodiment of the present application.

Fig. 3 is a circuit diagram of a first embodiment of a battery protection circuit in the battery management system of fig. 1.

Fig. 4 is a circuit diagram of a second embodiment of a battery protection circuit in the battery management system of fig. 1.

Fig. 5 is a flowchart of a control method of a battery device according to a first preferred embodiment of the present application.

Description of the main elements

Battery device 100

Cell unit 200

Battery protection circuit 300

Battery management system 400

External connection port 500

First protection unit 30

Second protection unit 31

Sensing switch unit 32

Third protection unit 33

A first resistor R1

Resistors R0, R1 'to R7'

Fuse 310

First switch Q1

Second switch Q2

Third switch Q3

First protection chips IC1, IC2, IC3

Second protection chip IC1', IC2' and IC3'

Second to seventh resistors R2 to R7

First to twelfth cells B1 to B12

First pins CV0, VSS

Second pins CV1, V1

Third pins CV2, V4

Fourth pins CV3, V5

Charging pin CHG

Discharge pin DSG

Charge enable pin CTRC

Discharge enable pin CTRD

Output pin OUT

The following detailed description will further illustrate the present application in conjunction with the above-described figures.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the term "connected" is to be interpreted broadly, e.g. as a fixed connection, a detachable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; they may be connected directly or indirectly through intervening elements, or may be connected through inter-element communication or may be in the interaction of two elements. To those of ordinary skill in the art, the above terms may be immediately defined in the present invention according to their specific meanings.

The terms "first," "second," and "third," etc. in the description and claims of the present invention and the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "comprises" and any variations thereof, are intended to cover non-exclusive inclusions.

Referring to fig. 1, fig. 1 is a block diagram of a preferred embodiment of a battery device according to the present application. The battery device 100 includes a cell unit 200 and a battery protection circuit 300 electrically connected to the cell unit 200. The battery protection circuit 300 is located in the battery management system 400, and is configured to protect the battery cell unit 200 when the battery management system 400 controls charging and discharging of the battery cell unit 200. The battery protection circuit 300 is electrically connected between the battery cell unit 200 and the external port 500 to form a power supply loop, and the battery protection circuit 300 is configured to control the power supply loop to be turned on or off, so as to protect the battery cell unit 200 when the battery management system 400 controls the battery cell unit 200 to charge and discharge.

The battery protection circuit 300 includes a first protection unit 30, a second protection unit 31, and a sensing switch unit 32.

Specifically, in the embodiment of the present application, the first protection unit 30 is electrically connected between the battery cell unit 200 and the second protection unit 31. The sensing switch unit 32 is disposed at a preset position of the battery cell unit 200, and the sensing switch unit 32 is electrically connected to the second protection unit 31. In a normal use state, the sensing switch unit 32 is in an off state. If the first protection unit 30 does not disconnect the power supply loop and the sensing switch unit 32 is turned on, the second protection unit 31 may be triggered to protect the battery cell unit 200. It is understood that the preset position may be set according to the sensing switch unit 32. For example, when the sensing switch unit 32 is a temperature switch, the preset position is a position where a highest temperature point on the surface of the battery cell unit 200 is located. When the sensing switch unit 32 is a microswitch, the preset position is the position where the surface of the battery cell unit 200 is most easily expanded. It should be noted that the location of the highest temperature point or the most easily expandable point of the cell unit 200 is already determined when the cell unit 200 is shipped from the factory. For example, thermal simulation and test are performed according to the battery system, chemical composition and structure of the cell unit 200, and the location of the highest temperature point or the most easily expandable point of the cell unit 200 under the battery system can be obtained. It is understood that the highest temperature point or the most easily expandable point of the surface of the cell units 200 of different battery systems is not the same. In an embodiment, the first protection unit 30 includes a plurality of first protection chips for protecting each cell in the cell unit 200.

In one embodiment, referring to fig. 3, the second protection unit 31 includes a fuse 310, a first resistor R1, and a first switch Q1. The fuse 310 is a three-terminal fuse. A first end of the fuse 310 is connected to the positive electrode of the battery cell unit 200, a second end of the fuse 310 is connected to a second end of the first switch Q1 through the first resistor R1, and a third end of the fuse 310 is connected to the positive electrode of the external port 500; the first terminal of the first switch Q1 is electrically connected to the sensing switch unit 32, the third terminal of the first switch Q1 is electrically connected to the second terminal of the fuse 310, and the second terminal of the first switch Q1 is grounded. The first switch Q1 may be an N-type field effect transistor. The first end, the second end and the third end of the first switch Q1 respectively correspond to the grid electrode, the source electrode and the drain electrode of the N-type field effect transistor.

In an embodiment, the sensing switch unit 32 is used for sensing the temperature or the expansion amplitude or the pressure when the battery cell unit 200 is pressed. For example, the sensing switch unit 32 is a temperature switch, and can detect the temperature of the preset position of the battery cell unit 200 and compare the detected temperature with the preset temperature. When the detected temperature is higher than the preset temperature, the temperature switch is triggered to be turned on, so that the first switch Q1 is triggered to be turned on to heat the first resistor R1, and the fuse 310 is blown out to protect the battery cell unit 200.

In another embodiment, the sensing switch unit 32 is a micro switch. When the battery cell unit 200 is heated, it expands, and when the battery cell unit 200 is extruded (for example, the casing extrudes the battery cell unit 200), the microswitch is triggered to be turned on, so as to trigger the first switch Q1 to be turned on to heat the first resistor R1, and fuse 310 is blown to protect the battery cell unit 200.

It should be noted that the sensing switch unit 32 may also be replaced by other components with similar temperature switching characteristics or mechanical components. For example, the sensing switch unit 32 may also be a displacement sensing switch for detecting the thermal expansion amplitude of the cell unit 200. When the detected amplitude exceeds a preset amplitude, the displacement sensing switch is triggered to be turned on, so that the first switch Q1 is triggered to be turned on to heat the first resistor R1, and the fuse 310 is blown to protect the battery cell unit 200.

In one embodiment, the positive electrode of the external port 500 may be electrically connected to the positive electrode of a charger (not shown), and the negative electrode of the external port 500 may be electrically connected to the negative electrode of the charger.

In one embodiment, the battery protection circuit 300 further includes a third protection unit 33, as shown in fig. 2. The third protection unit 33 is electrically connected between the cell unit 200 and the second protection unit 31. If the first protection unit 30 does not disconnect the power supply loop, the third protection unit 33 does not trigger the second protection unit 31, and the sensing switch unit 32 is turned on, the second protection unit 31 is triggered to protect the battery cell unit 200. The third protection unit 33 includes a plurality of second protection chips for combining each cell in the dual protection cell unit 200 with the first protection unit 30.

In an embodiment, if the first protection unit 30 fails and the third protection unit 33 is triggered, a driving signal may be output to the second protection unit 31 to trigger the second protection unit 31 to protect the battery cell unit 200. If the first protection unit 30 fails and the third protection unit 33 also fails, the second protection unit 31 may be triggered by the sensing switch unit 32 to protect the battery cell unit 200.

It should be noted that, when the parameter of the battery cell unit 200 is greater than or equal to a first preset parameter, the first protection unit 30 fails to describe that the power supply circuit is not turned off by the first protection unit 30 (for example, the second switch Q2 or the third switch Q3 is turned off). The parameter of the cell unit 200 may be current, voltage, or temperature. It is understood that, when the parameter is temperature, the preset temperature corresponding to the first protection unit 30 is lower than the temperature at which the sensing switch unit 32 is triggered. For example, the first preset temperature corresponding to the first protection unit 30 is 50 degrees celsius, and the temperature at which the sensing switch unit 32 is triggered is the highest temperature (e.g., 70 degrees celsius) that the battery cell unit 200 can bear.

It can be understood that, when the parameter of the battery cell 200 is greater than or equal to a second preset parameter, the third protection unit 33 fails to describe that the first protection unit 30 does not trigger the second protection unit 31. The second preset parameter is greater than the first preset parameter and is smaller than the threshold value of the sensing switch unit 32 when triggered.

For example, when the voltage of the cell unit 200 exceeds a preset voltage and reaches a voltage threshold for triggering the first protection unit 30, the first protection unit 30 may be triggered to protect the cell unit 200.

If the voltage of the battery cell unit 200 exceeds a preset voltage and reaches a voltage threshold value for triggering the first protection unit 30, but the first protection unit 30 fails; determining whether the voltage of the battery cell unit 200 reaches a voltage threshold for triggering the third protection unit 33, and if the voltage of the battery cell unit 200 reaches the voltage threshold for triggering the third protection unit 33, triggering the third protection unit 33 to output a driving signal to the second protection unit 31, so as to control the second protection unit 31 to protect the battery cell unit 200.

If the voltage of the battery cell unit 200 exceeds a preset voltage and reaches a voltage threshold value for triggering the first protection unit 30, but the first protection unit 30 fails; determining whether the voltage of the battery cell unit 200 reaches a voltage threshold for triggering the third protection unit 33, and if the voltage of the battery cell unit 200 reaches the voltage threshold for triggering the third protection unit 33, but the third protection unit 33 fails, outputting a driving signal to the second protection unit 31 after the sensing switch unit 32 is triggered and turned on, so as to control the second protection unit 31 to protect the battery cell unit 200.

Referring to fig. 3, fig. 3 is a circuit diagram of a battery protection circuit 300 according to a first embodiment of the present application.

In the present embodiment, the first protection unit 30 includes three first protection chips, and four cells are connected to each first protection chip. For example, the first protection unit 30 includes a first protection chip IC1, a first protection chip IC2, a first protection chip IC3, a second resistor R2, a third resistor R3 \8230anda seventh resistor R7. The battery cell unit 200 comprises a first battery cell B1, a second battery cell B2 \8230, and a twelfth battery cell B12. In an embodiment, the primary protection chip IC1 is connected to the first cell B1 to the fourth cell B4 to protect the first cell B1 to the fourth cell B4. For example, one end of the second resistor R2 is connected to the positive electrode of the first cell B1, and the other end of the second resistor R2 is connected to the negative electrode of the first cell B1. One end of the second resistor R2 is further connected to the first pin CV0 of the first protection chip IC1, and the other end of the second resistor R2 is further connected to the second pin CV1 of the first protection chip IC 1. One end of a fifth resistor R5 is connected to the positive electrode of the fourth battery cell B4, and the other end of the fifth resistor R5 is connected to the negative electrode of the fourth battery cell B4. One end of the fifth resistor R5 is further connected to the third pin CV3 of the first protection chip IC1, and the other end of the fifth resistor R5 is further connected to the fourth pin CV4 of the first protection chip IC 1.

It should be noted that, by analogy, the first protection chip IC2 is connected to the fifth cell B5 to the eighth cell B8 to protect the fifth cell B5 to the eighth cell B8. The first protection chip IC3 is connected to the ninth cell B9 to the twelfth cell B12 to protect the ninth cell B9 to the twelfth cell B12. A specific connection manner is similar to that of the first protective chip IC1 connecting the first cell B1 to the fourth cell B4, and is not described in detail here. It should be noted that the first protection unit 30 may include N first protection chips, and the number of the first protection chips is not limited in this application.

The first protection unit 30 further includes a second switch Q2, a third switch Q3, and a resistor R0. The resistor R0 is used to collect a current of a power supply loop, that is, a current flowing through the battery cell unit 200. In this embodiment, one end of the resistor R0 is connected to the negative electrode of the first cell B1, and the other end of the resistor R0 is connected to the second switch Q2. One end of the resistor R0 is further connected with the SRP pin of the first protection chip IC1, and the other end of the resistor R0 is further connected with the SRN pin of the first protection chip IC 1. The first protection chip IC1 may detect the voltage of the resistor R0, so as to calculate the current flowing through the battery cell unit 200 according to the voltage and the resistance of the resistor R0.

A first end of the second switch Q2 is connected to a discharge pin DSG of the first protection chip IC1, a second end of the second switch Q2 is connected to the resistor R0, and a third end of the second switch Q2 is connected to a second end of the third switch Q3; a first end of the third switch Q3 is connected to the charging pin CHG of the first protection chip IC1, a third end of the third switch Q3 is connected to a third end of the second switch Q2, and a second end of the third switch Q3 is connected to a negative electrode of the external port 500.

The second switch Q2 and the third switch Q3 may be N-type field effect transistors. The first end, the second end and the third end of the second switch Q2 and the third switch Q3 respectively correspond to the grid electrode, the source electrode and the drain electrode of the N-type field effect transistor.

In the present embodiment, the first protection chip IC1, the first protection chip IC2 and the first protection chip IC3 are cascaded, so that the second switch Q2 and the third switch Q3 can be controlled to control the on and off of the power supply circuit. Specifically, the charging pin CHG of the first protection chip IC3 is connected to the charging enable pin CTRC of the first protection chip IC2, and the discharging pin DSG of the first protection chip IC3 is connected to the discharging enable pin CTRD of the first protection chip IC 2; a charging pin CHG of the first protection chip IC2 is connected with a charging enable pin CTRC of the first protection chip IC1, and a discharging pin DSG of the first protection chip IC2 is connected with a discharging enable pin CTRD of the first protection chip IC 1; a charging pin CHG of the first protection chip IC1 is connected to the third switch Q3, and a discharging pin DSG of the first protection chip IC1 is connected to the second switch Q2. When any one of the first protection chip IC1 to the first protection chip IC3 detects that the battery cell 200 is overcharged or overdischarged, the charge enable pin CTRC or the discharge enable pin CTRD enables the charge pin CHG or the discharge pin DSG to output a driving signal, so as to control the second switch Q2 or the third switch Q3 to be turned off, thereby achieving the purpose of protecting the battery cell 200.

In a normal use state, the sensing switch unit 32 is in an open state, the second end of the fuse 310 in the second protection unit 31 is connected to the second end of the first switch Q1, and the power supply loop works normally. If the first protection unit 30 in the power supply loop fails, the first protection unit 30 does not control the second switch Q2 or the third switch Q3 to be turned off, so as to disconnect the power supply loop. The battery cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the battery cell temperature rises to a threshold value, or the battery cell expands when heated, or the battery cell extrudes when heated), and triggers the sensing switch unit 32 to turn on. Therefore, the first switch Q1 is triggered to be switched on to heat the first resistor, the fuse is fused, the power supply loop is disconnected, continuous charging or discharging is avoided, and the battery cell unit 200 is prevented from being ignited or exploded.

In one embodiment, when the battery management system 400 controls the cell unit 200 to discharge at a predetermined current (e.g., 3C-6C current is continuously discharged), the fuse 310 cannot be blown. That is, the battery management system 400 controls the cell unit 200 to perform continuous discharge at a current near the rated current of the fuse 310. The cell unit 200 is caused to be abnormal due to continuous high-rate discharge (for example, the cell temperature rises to a temperature threshold value that can be borne by the sensing switch unit, or the amplitude of the thermal expansion of the cell exceeds an amplitude threshold value, or the pressure of the thermal extrusion of the cell is greater than a pressure threshold value), and the sensing switch unit 32 is triggered to be switched on. Therefore, the first switch Q1 is triggered to be turned on to heat the first resistor R1, so as to fuse the fuse 310, and dangerous accidents such as fire and explosion caused by continuous discharge of the battery cell unit 200 are avoided. In one embodiment, the difference between the rated current of the fuse 310 and the preset current is less than or equal to a current threshold.

Referring to fig. 4, fig. 4 is a circuit diagram of a battery protection circuit 300 according to a second embodiment of the present invention.

The battery protection circuit 300 of the present embodiment differs from the battery protection circuit 300 of the first embodiment in that:

in one embodiment, the battery protection circuit 300 further includes a third protection unit 33. The third protection unit 33 is electrically connected between the battery cell unit 200 and the second protection unit 31. The third protection unit 33 includes a plurality of second protection chips for doubly protecting each cell in the cell unit 200 in combination with the first protection unit 30.

For example, it is explained that the third protection unit 33 includes three second protection chips, and each of the second protection chips is connected to four battery cells. The third protection unit 33 includes a second protection cell IC1', a second protection cell IC2', a second protection cell IC3', a resistor R1', a resistor R2 '\ 8230, and a resistor R7'. In an embodiment, the second protection chip IC1' is connected to the first to fourth battery cells B1 to B4 to perform secondary protection on the first to fourth battery cells B1 to B4. For example, a first pin VSS of the second protection chip IC1' is connected to the negative electrode of the first battery cell B1, and a second pin V1 of the second protection chip IC1' is connected to the positive electrode of the first battery cell B1 through a resistor R1 '; and a third pin V4 and a fourth pin V5 of the second protection chip IC1 'are connected and then connected with the anode of the fourth battery cell B4 through a resistor R2'.

It should be noted that, by analogy, the second protection chip IC2' is connected to the fifth cell B5 to the eighth cell B8, so as to protect the fifth cell B5 to the eighth cell B8. The second protection chip IC3' is connected to the ninth cell B9 to the twelfth cell B12 to protect the ninth cell B9 to the twelfth cell B12. The specific connection manner is similar to the connection manner of the second protection chip IC1' to the first cell B1 to the fourth cell B4, and is not described in detail here. It should be noted that the third protection unit 33 may include N second protection chips, and the number of the second protection chips is not limited in this application.

In this embodiment, the output pin OUT of the second protection chip IC1', the output pin OUT of the second protection chip IC2' and the output pin OUT of the second protection chip IC3' are connected to the first end (for example, F1-C) of the first switch Q1. When the first protection unit 30 (i.e., the first protection chips IC1 to IC 3) fails, the battery cell unit 200 may be overcharged or overdischarged, and the third protection unit 33 may output a driving signal to the first switch Q1 to drive the first switch Q1 to be turned on, so as to heat the first resistor R1 to fuse the fuse 310, thereby preventing accidents such as ignition and explosion caused by continuous charging or discharging of the battery cell unit 200.

In a normal use state, the sensing switch unit 32 is in an off state, and the power supply circuit works normally. And in the case where both the first protection unit 30 and the third protection unit 33 fail. That is, the first protection unit 30 does not control the second switch Q2 or the third switch Q3 to be turned off to disconnect the power supply loop, and the third protection unit 33 does not trigger the second protection unit 31. The battery cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the battery cell temperature rises to a temperature threshold value that can be borne by the sensing switch unit, or the amplitude of thermal expansion of the battery cell exceeds an amplitude threshold value, or the pressure of thermal extrusion of the battery cell is greater than a pressure threshold value), and the sensing switch unit 32 is triggered to be switched on, so that the first switch Q1 is triggered to be switched on to heat the first resistor R1, the fuse 310 is fused to protect the battery cell unit 200, and accidents such as fire and explosion are avoided.

Similarly, when the battery management system 400 controls the cell unit 200 to discharge at a predetermined current, for example, a 3C-6C current is continuously discharged, the fuse cannot be blown. That is, the battery management system 400 continuously discharges at a current close to the rated current of the fuse 310, and the difference between the rated current of the fuse 310 and the preset current is less than or equal to the current threshold. The cell unit 200 is caused to be abnormal due to continuous high-rate discharge (for example, the cell temperature rises to a temperature threshold value that can be borne by the sensing switch unit, or the amplitude of the thermal expansion of the cell exceeds an amplitude threshold value, or the pressure of the thermal extrusion of the cell is greater than a pressure threshold value), and the sensing switch unit 32 is triggered to be switched on. Thereby triggering the first switch Q1 to be turned on to heat the first resistor R1, fusing the fuse 310, and avoiding dangerous accidents such as fire and explosion caused by continuous discharge of the battery cell unit 200.

As shown in fig. 5, fig. 5 is a flowchart of a control method of a battery device according to an embodiment of the present application. The control method of the battery device may include the steps of:

step S1: and under the condition that the sensing switch unit is triggered to be switched on and the first protection unit does not cut off the power supply loop, controlling the second protection unit to protect the battery cell unit.

In the present embodiment, the battery device 100 includes a battery cell unit 200 and a battery protection circuit 300 electrically connected to the battery cell unit 200, the battery protection circuit 300 is electrically connected between the battery cell unit 200 and an external port 500 to form a power supply loop, and the battery protection circuit 300 includes a first protection unit 30, a second protection unit 31 and a sensing switch unit 32.

In a normal use state, the sensing switch unit 32 is in an open state, the second end of the fuse 310 in the second protection unit 31 is connected to the second end of the first switch Q1, and the power supply loop works normally. If the first protection unit 30 in the power supply loop fails, the first protection unit 30 does not control the second switch Q2 or the third switch Q3 to be turned off so as to turn off the power supply loop. The battery cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the battery cell temperature rises to a threshold value, or the battery cell is heated to expand, or the battery cell is heated to extrude), and the sensing switch unit 32 is triggered to be switched on, so as to control the second protection unit to protect the battery cell unit. Namely, the first switch Q1 in the second protection unit is triggered to be turned on to heat the first resistor, fuse the fuse, disconnect the power supply loop, avoid continuous charging or discharging, and prevent the battery cell unit 200 from being ignited or exploded.

Step S2: under the condition that the sensing switch unit 32 is triggered to be turned on, the first protection unit 30 does not cut off the power supply loop, and the third protection unit 33 does not trigger the second protection unit 31, the second protection unit 31 is controlled to protect the battery cell unit.

In an embodiment, the method further comprises: when the battery management system 400 controls the cell unit 200 to discharge at a preset current, if the sensing switch unit 32 is turned on, the second protection unit 31 is triggered to protect the cell unit.

In the battery protection circuit 300 and the battery management system 400 having the battery protection circuit 300 provided in the above embodiments, the sensing switch unit 32 is disposed at the preset position of the battery cell unit 200, and the sensing switch unit 32 is electrically connected to the second protection unit 31, if the first protection unit 30 does not trigger the second protection unit 31, and the sensing switch unit 32 is triggered to be turned on, the second protection unit 31 is controlled to protect the battery cell unit 200. The battery management system 400 can effectively avoid the occurrence of the fire and explosion accidents of the battery cell unit 200 caused by overcharge, overdischarge or discharge with a current high magnification close to the rated current of the fuse 310 under the condition of single-point failure. The battery protection circuit 300 provided by the application has the advantages of high safety, wide application range, low cost and the like.

It should be understood by those skilled in the art that the above embodiments are only for illustrating the present application and are not used as limitations of the present application, and that suitable modifications and changes of the above embodiments are within the scope of the claims of the present application as long as they are within the spirit and scope of the present application.

Claims

1. A battery protection circuit is characterized in that the battery protection circuit is electrically connected between a cell unit and an external port to form a power supply loop, and comprises a first protection unit, a second protection unit and a sensing switch unit;

the first protection unit is electrically connected between the battery cell unit and the second protection unit;

the sensing switch unit is arranged at a preset position of the battery cell unit and is electrically connected with the second protection unit;

the preset position is set according to different types of the sensing switch units, and the sensing switch units arranged at the preset position are configured to be triggered to be conducted; and

2. The battery protection circuit of claim 1, wherein the second protection unit comprises a fuse, a first resistor and a first switch, a first end of the fuse is configured to be electrically connected to the positive electrode of the cell unit, a second end of the fuse is electrically connected to a second end of the first switch through the first resistor, and a third end of the fuse is electrically connected to the positive electrode of the external port; the first end of the first switch is electrically connected with the sensing switch unit, the second end of the first switch is grounded, and the third end of the first switch is electrically connected with the second end of the fuse.

3. The battery protection circuit of claim 2, wherein the sensing switch unit is a temperature switch, and if the temperature switch detects that the temperature of the cell unit exceeds a preset temperature, the temperature switch is triggered to be turned on, so as to trigger the first switch to be turned on to heat the first resistor, and the fuse is blown to protect the cell unit.

4. The battery protection circuit of claim 2, wherein the sensing switch unit is a micro switch, and if the cell unit is squeezed due to thermal expansion, the micro switch is triggered to be turned on, so as to trigger the first switch to be turned on to heat the first resistor, and the fuse is blown to protect the cell unit.

5. The battery protection circuit of claim 1, further comprising a third protection unit electrically connected between the cell unit and the second protection unit.

6. The battery protection circuit of claim 5, wherein the second protection unit is controlled to protect the cell unit in a case where the sensing switch unit is triggered to be turned on, the first protection unit does not turn off the power supply loop, and the third protection unit does not trigger the second protection unit.

7. A battery management system, characterized in that it comprises a battery protection circuit according to any one of claims 1 to 6.

8. The battery management system of claim 7, wherein when the battery management system controls the cell unit to discharge at a preset current, if the sensing switch unit is turned on, the second protection unit is triggered to protect the cell unit.

9. The battery management system of claim 8, wherein the second protection unit comprises a fuse having a rated current that differs from the preset current by less than or equal to a current threshold.

10. A battery device including a cell unit, wherein the battery device further includes the battery protection circuit according to any one of claims 1 to 6, and the battery protection circuit is configured to protect the cell unit.

11. A control method of a battery device, the battery device including a cell unit and a battery protection circuit electrically connected to the cell unit, wherein the battery protection circuit is electrically connected between the cell unit and an external port to form a power supply loop, the battery protection circuit includes a first protection unit, a second protection unit and a sensing switch unit, the sensing switch unit is disposed at a preset position of the cell unit, the preset position is set according to different types of the sensing switch unit, and the sensing switch unit disposed at the preset position is triggered to be turned on, the method including:

12. The method for controlling the battery device according to claim 11, wherein the battery protection circuit further includes a third protection unit electrically connected between the cell unit and the second protection unit, and the method further includes:

13. The method for controlling a battery device according to claim 11, the battery device including a battery management system, the method further comprising:

14. The control method of the battery device according to claim 13, wherein the second protection unit includes a fuse whose rated current differs from the preset current by less than or equal to a current threshold value.