CN111668901A - Battery protection circuit, battery management system, battery device and control method thereof - Google Patents

Abstract

The present application provides a battery protection circuit. The battery protection circuit is electrically connected between a battery cell unit and an external port to form a power supply circuit. The battery protection circuit includes a first protection unit, a second protection unit and a sensing switch unit. ; the first protection unit is electrically connected between the cell unit and the second protection unit; the sensing switch unit is arranged at a preset position of the cell unit, and the sensing switch unit is connected to the second protection unit The two protection units are electrically connected; when the sensing switch unit is triggered and turned on, and the first protection unit does not cut off the power supply circuit, the second protection unit is controlled to protect the battery cell unit. The present application also provides a battery management system, a battery device and a control method thereof. The battery protection circuit provided in the present application has the advantages of high safety, wide application range, low cost, and the like.

Description

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

technical field

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

Background technique

At present, lithium-ion batteries have been widely used as an important energy source. Whether in the field of electronic communication or transportation, they have played an extremely important role and have broad application prospects. The safety of lithium-ion batteries is also an issue that cannot be ignored.

Lithium-ion batteries are generally safe when used according to specifications, but can become potentially dangerous in the event of an internal or mechanical failure. For example, when the battery is under abusive conditions such as overcharge, crush, high temperature or short circuit. May cause overheating, fumes or even fire and explosion. In the prior art, lithium-ion battery protection chips can monitor the charging and discharging process and intervene when there is a risk that the process may exceed the safe operating range of the battery. However, when the lithium-ion battery protection chip fails, there is no risk warning for the battery.

SUMMARY OF THE INVENTION

In view of the above, it is necessary 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 battery cells.

An embodiment of the present application provides a battery protection circuit, the battery protection circuit is electrically connected between a battery cell unit and an external port to form a power supply circuit, the battery protection circuit includes a first protection unit, a second protection unit, and a sensing switch unit; the first protection unit is electrically connected between the cell unit and the second protection unit; the sensing switch unit is set at a preset position of the cell unit, and the sensing switch unit is electrically connected to the second protection unit; and when the sensing switch unit is triggered and turned on, and the first protection unit does not cut off the power supply circuit, the second protection unit is controlled to protect the the cell unit.

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, and a second end of the fuse passes through The first resistor is connected to the second end of the first switch, the third end of the fuse is connected to the positive pole of the external port; the first end of the first switch is electrically connected to the sensing switch unit , the second end of the first switch is grounded, and the third end of the first switch is electrically connected to 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 switch detects that the temperature of the cell unit exceeds a preset temperature, the temperature switch is triggered to be turned on, thereby triggering the first The switch is turned on to heat the first resistor, and the fuse is blown to protect the cell unit.

According to some embodiments of the present application, the sensing switch unit is a micro switch. If the cell unit is thermally expanded and squeezed, the micro switch is triggered to conduct, thereby triggering the first switch to conduct To heat the first resistor, the fuse is blown to protect the cell unit.

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

According to some embodiments of the present application, when the sensing switch unit is triggered to be turned on, the first protection unit does not turn off the power supply circuit, and the third protection unit does not trigger the second protection unit , controlling the second protection unit to protect the battery cell unit.

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

According to some embodiments of the present application, when the battery management system controls the battery 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 battery cell core unit.

According to some embodiments of the present application, the second protection unit includes a fuse, and a difference between the rated current of the fuse and the preset current is less 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, and the battery device further includes the above-mentioned battery protection circuit, where the battery protection circuit is used to protect the battery cell unit.

An embodiment of the present application provides a control method for a battery device, the battery device includes a battery cell unit and a battery protection circuit electrically connected to the battery cell unit, the battery protection circuit is electrically connected to the battery 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, and the method includes:

When the sensing switch unit is triggered and turned on, and the first protection unit does not cut off the power supply circuit, the second protection unit is controlled to protect the battery cell unit.

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

When the sensing switch unit is triggered to be turned on, the first protection unit does not cut off the power supply circuit, and the third protection unit does not trigger the second protection unit, the second protection unit is controlled The unit protects the cell unit.

According to some embodiments of the present application, the battery device includes a battery management system, and the method further includes:

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 turned on, the second protection unit is controlled to protect the battery cell unit.

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

In the battery protection circuit and the battery management system with the battery protection circuit provided by the embodiments of the present application, a sensing switch unit is provided at a preset position of the battery cell unit, and the sensing switch unit is connected to the second The protection unit is electrically connected, and if the first protection unit does not trigger the second protection unit and the sensing switch unit is triggered and turned on, the second protection unit is controlled to protect the battery cell unit. The present application can effectively avoid the fire and explosion accident of the battery cell unit caused by overcharging, overdischarging or discharging at a high rate of current close to the rated current of the fuse in the case of a single point failure of the battery management system. The battery protection circuit provided by the present application has the advantages of high safety, wide application range, low cost, and the like.

Description of 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 the battery protection circuit in the battery management system of FIG. 1 .

FIG. 4 is a circuit diagram of a second embodiment of the 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 the first preferred embodiment of the present application.

Description of main component symbols

battery unit 100

Cell unit 200

battery protection circuit 300

Battery Management System 400

External port 500

first protection unit 30

second protection unit 31

Sensing switch unit 32

third protection unit 33

The first resistor R1

Resistors R0, R1'～R7'

Fuse 310

The first switch Q1

Second switch Q2

The third switch Q3

The first protection chip IC1, IC2, IC3

The second protection chip IC1', IC2', IC3'

The second resistor to the seventh resistor R2～R7

The first cell to the twelfth cell B1～B12

The first pin CV0, VSS

The second pin CV1, V1

The third pin CV2, V4

The fourth pin CV3, V5

Charge pin CHG

Discharge pin DSG

Charge Enable Pin CTRC

Discharge Enable Pin CTRD

output pin OUT

The following specific embodiments will further illustrate the present application in conjunction with the above drawings.

Detailed ways

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only Embodiments are part of the present invention, but not all embodiments.

In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified and limited, the term "connection" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection ; It can be a mechanical connection, an electrical connection or mutual communication; it can be a direct connection or an indirect connection through the intermediate connection, and it can be the internal communication between the two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be immediately understood according to specific situations.

The terms "first", "second" and "third" in the description and claims of the present invention and the above drawings are used to distinguish different objects, rather than to describe a specific order. Furthermore, the term "comprising" and any variations thereof are intended to cover non-exclusive inclusion.

Please refer to FIG. 1 , which is a block diagram of a preferred embodiment of a battery device according to the present application. 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 located in the battery management system 400 and is used 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 is electrically connected between the battery cell unit 200 and the external port 500 to form a power supply loop. The system 400 protects the battery cell unit 200 when the battery cell unit 200 is controlled to be charged and discharged.

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 circuit and the sensing switch unit 32 is turned on, the second protection unit 31 can be triggered to protect the battery cell unit 200 . It can be understood that, the preset position can be set according to the difference of the sensing switch unit 32 . For example, when the sensing switch unit 32 is a temperature switch, the preset position is the position of the highest temperature point on the surface of the cell unit 200 . When the sensing switch unit 32 is a micro switch, the preset position is the most easily expanded position on the surface of the cell unit 200 . It should be noted that, the position of the highest temperature point or the most likely expansion point of the battery cell unit 200 has been determined when the battery cell unit 200 is shipped from the factory. For example, by performing thermal simulation and testing according to the battery system, chemical composition and structure of the battery cell 200 , the position of the highest temperature point or the easiest expansion point of the battery cell 200 in the battery system can be obtained. It can be understood that the locations of the highest point of the surface temperature or the point of the easiest expansion of the surface of the cell unit 200 of different battery systems are not the same. In one 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, as shown in 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. The first end of the fuse 310 is connected to the positive pole of the cell unit 200, the second end of the fuse 310 is connected to the second end of the first switch Q1 through the first resistor R1, and the fuse The third terminal of 310 is connected to the positive pole of the external port 500 ; the first terminal of the first switch Q1 is electrically connected to the sensing switch unit 32 , and the third terminal of the first switch Q1 is electrically connected to the fuse 310 The second terminal of the first switch Q1 is electrically connected, 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 correspond to the gate electrode, the source electrode and the drain electrode of the N-type field effect transistor, respectively.

In one embodiment, the sensing switch unit 32 is used to sense the temperature or the expansion amplitude of the cell unit 200 or the pressure when being squeezed. For example, the sensing switch unit 32 is a temperature switch, which can detect the temperature of the predetermined position of the cell unit 200 and compare the detected temperature with the predetermined temperature. When the detected temperature is greater than the preset temperature, the temperature switch is triggered to conduct, thereby triggering the first switch Q1 to conduct to heat the first resistor R1, and to blow the fuse 310 to protect all The cell unit 200 is described.

In another embodiment, the sensing switch unit 32 is a micro switch. When the battery cell unit 200 is heated, it will expand, and when the battery cell unit 200 is squeezed after expansion (for example, the casing squeezes the battery cell unit 200 ), the microswitch is triggered to turn on, Thus, the first switch Q1 is turned on to heat the first resistor R1 , and the fuse 310 is blown to protect the cell unit 200 .

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

In one embodiment, the positive electrode of the external port 500 can be electrically connected to the positive electrode of a charger (not shown in the figure), and the negative electrode of the external port 500 can 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 battery cell unit 200 and the second protection unit 31 . If the first protection unit 30 does not disconnect the power supply circuit, and the third protection unit 33 does not trigger the second protection unit 31, and the sensing switch unit 32 is turned on, trigger the The second protection unit 31 protects the battery cell unit 200 . The third protection unit 33 includes a plurality of second protection chips for combining with the first protection unit 30 to double protect each cell in the cell unit 200 .

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

It should be noted that the failure of the first protection unit 30 describes that when the parameter of the cell unit 200 is greater than or equal to the first preset parameter, the first protection unit 30 does not cut off the power supply circuit (eg cut off The second switch Q2 or the third switch Q3). The parameter of the cell unit 200 may be current, voltage or temperature. It can be understood that when the parameter is temperature, the preset temperature corresponding to the first protection unit 30 will be lower than the temperature when 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 when the sensing switch unit 32 is triggered is the highest temperature (eg, 70 degrees Celsius) that the battery cell unit 200 can withstand. .

It can be understood that the failure of the third protection unit 33 describes that when the parameter of the cell unit 200 is greater than or equal to the second preset parameter, the first protection unit 30 does not trigger the second protection unit 31 . The second preset parameter is larger than the first preset parameter and smaller than the threshold when the sensing switch unit 32 is 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 cell unit 200 exceeds the preset voltage and reaches the voltage threshold for triggering the first protection unit 30, but the first protection unit 30 fails; confirm whether the voltage of the cell unit 200 reaches the triggering value The voltage threshold of the third protection unit 33, if the voltage of the cell unit 200 reaches the voltage threshold that triggers the third protection unit 33, the third protection unit 33 can be triggered to output a drive signal to the third protection unit 33. Two protection units 31 to control the second protection unit 31 to protect the battery cell unit 200 .

If the voltage of the cell unit 200 exceeds the preset voltage and reaches the voltage threshold for triggering the first protection unit 30, but the first protection unit 30 fails; confirm whether the voltage of the cell unit 200 reaches the triggering value The voltage threshold of the third protection unit 33, if the voltage of the cell unit 200 reaches the voltage threshold that triggers the third protection unit 33, but the third protection unit 33 fails, the sensing switch unit After 32 is triggered and turned on, a driving signal is output to the second protection unit 31 to control the second protection unit 31 to protect the battery cell unit 200 .

Please refer to FIG. 3 , which is a circuit diagram of a first embodiment of a battery protection circuit 300 according to the present application.

In this embodiment, the first protection unit 30 includes three first protection chips for description, and each first protection chip is connected to four battery cells. 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 . . . a seventh resistor R7 . The cell unit 200 includes a first cell B1 , a second cell B2 , and a twelfth cell B12 . In one 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 battery cell B1, and the other end of the second resistor R2 is connected to the negative electrode of the first battery cell B1. One end of the second resistor R2 is also connected to the first pin CV0 of the first protection chip IC1, and the other end of the second resistor R2 is also connected to the second pin CV1 of the first protection chip IC1 . One end of the 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 also connected to the third pin CV3 of the first protection chip IC1, and the other end of the fifth resistor R5 is also connected to the fourth pin CV4 of the first protection chip IC1.

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. The specific connection manner is similar to the connection manner in which the first protection chip IC1 connects the first battery cell B1 to the fourth battery cell B4, and will not be described in detail here. It should be noted that the first protection unit 30 may include N first protection chips, and the present application does not limit the number of the first protection chips.

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 the current of the power supply circuit, that is, the current flowing through the cell unit 200 . In this embodiment, one end of the resistor R0 is connected to the negative electrode of the first battery cell B1, and the other end of the resistor R0 is connected to the second switch Q2. One end of the resistor R0 is also connected to the SRP pin of the first protection chip IC1, and the other end of the resistor R0 is also connected to the SRN pin of the first protection chip IC1. The first protection chip IC1 can detect the voltage of the resistor R0, so as to obtain the current flowing through the cell unit 200 according to the voltage and the resistance value of the resistor R0.

The first end of the second switch Q2 is connected to the discharge pin DSG of the first protection chip IC1, the second end of the second switch Q2 is connected to the resistor R0, and the second end of the second switch Q2 is connected to the resistor R0. The three terminals are connected to the second terminal of the third switch Q3; the first terminal of the third switch Q3 is connected to the charging pin CHG of the first protection chip IC1, and the third terminal of the third switch Q3 It is connected to the third end of the second switch Q2 , and the second end of the third switch Q3 is connected to the 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 correspond to the gate electrode, the source electrode and the drain electrode of the N-type field effect transistor, respectively.

In this embodiment, the first protection chip IC1, the first protection chip IC2, and the first protection chip IC3 are cascaded, so that the conduction and the power supply loop can be controlled by controlling the second switch Q2 and the third switch Q3. deadline. 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 of the first protection chip IC2. can be connected to pin CTRD; the charging pin CHG of the first protection chip IC2 is connected to the charging enable pin CTRC of the first protection chip IC1, and the discharge pin DSG of the first protection chip IC2 is connected to the first protection chip IC1 The discharge enable pin CTRD is connected; the charging pin CHG of the first protection chip IC1 is connected to the third switch Q3, and the discharge 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 cell unit 200 is overcharged or overdischarged, the charging enable pin CTRC or the discharge enable pin CTRD can be used to enable The charging pin CHG or the discharging pin DSG can output a driving signal to control the second switch Q2 or the third switch Q3 to be turned off, so as to achieve the purpose of protecting the cell unit 200 .

In a normal use state, the sensing switch unit 32 is in an off 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 circuit works normally. If the first protection unit 30 in the power supply circuit 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 circuit. When the cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the cell temperature rises to a threshold value or the cell is thermally expanded or the cell is thermally squeezed), the sensing switch unit 32 is triggered to be turned on. Thus, the first switch Q1 is triggered to be turned on to heat the first resistor, fuse the fuse, and disconnect the power supply circuit, so as to avoid continuous charging or discharging, and prevent the cell unit 200 from catching fire or exploding.

In one embodiment, when the battery management system 400 controls the battery cell 200 to discharge at a preset current (eg, 3C-6C current continues to discharge), the fuse 310 cannot be blown. That is, the battery management system 400 controls the battery cell 200 to discharge continuously at a current close to the rated current of the fuse 310 . The battery cell 200 is abnormal due to continuous high-rate discharge (for example, the temperature of the battery cell rises to a temperature threshold that the sensing switch unit can withstand, or the thermal expansion of the battery cell exceeds the threshold value, or the pressure of the thermal extrusion of the battery cell is greater than pressure threshold), triggering the sensing switch unit 32 to be turned on. Thus, the first switch Q1 is triggered to be turned on to heat the first resistor R1, and the fuse 310 is blown to prevent the battery cell 200 from continuing to discharge and causing dangerous accidents such as fire and explosion. 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.

Please refer to FIG. 4 , which is a circuit diagram of a second embodiment of the battery protection circuit 300 of the present application.

The difference between the battery protection circuit 300 of this embodiment and the battery protection circuit 300 of the first embodiment is 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 combining with the first protection unit 30 to double protect each cell in the cell unit 200 .

For example, it is described 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'... a resistor R7'. In one embodiment, the second protection chip IC1 ′ is connected to the first cell B1 to the fourth cell B4 to perform secondary protection for the first cell B1 to the fourth cell B4 . For example, the first pin VSS of the second protection chip IC1' is connected to the negative electrode of the first battery cell B1, and the second pin V1 of the second protection chip IC1' is connected to the second protection chip IC1' through a resistor R1'. The positive electrode of a battery cell B1 is connected; the third pin V4 and the fourth pin V5 of the second protection chip IC1 ′ are connected to the positive electrode of the fourth battery cell B4 through the 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 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 ′ connecting the first battery cells B1 to the fourth battery cells B4 , which will not be described in detail here. It should be noted that the third protection unit 33 may include N second protection chips, and the present application does not limit the number of the second protection chips.

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 protection chip IC3'. The first terminal of switch Q1 (eg F1-C) is connected. When the first protection unit 30 (ie, the first protection chips IC1 to IC3 ) fails, the cell unit 200 may be overcharged or overdischarged, and the third protection unit 33 may output a driving signal to the The first switch Q1 is used to drive the first switch Q1 to conduct, thereby heating the first resistor R1 to fuse the fuse 310 to prevent the battery cell 200 from continuing to be charged or discharged to cause accidents such as fire and explosion. .

In a normal use state, the sensing switch unit 32 is in an off state, and the power supply circuit works normally. And when both the first protection unit 30 and the third protection unit 33 fail. That is, when 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 circuit, and the third protection unit 33 does not trigger the second protection unit 31 . The cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the temperature of the cell rises to a temperature threshold that the sensing switch unit can withstand, or the thermal expansion of the cell exceeds the magnitude threshold or the power The pressure of the core being heated and squeezed is greater than the pressure threshold), the sensing switch unit 32 is triggered to conduct, thereby triggering the conduction of the first switch Q1 to heat the first resistor R1, and the fuse 310 is blown to protect the The battery cell unit 200 can avoid accidents such as fire and explosion.

Likewise, when the battery management system 400 controls the battery cell unit 200 to discharge at a preset current, for example, the current of 3C-6C continues to discharge, 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 battery cell 200 is abnormal due to continuous high-rate discharge (for example, the temperature of the battery cell rises to a temperature threshold that the sensing switch unit can withstand, or the thermal expansion of the battery cell exceeds the threshold value, or the pressure of the thermal extrusion of the battery cell is greater than pressure threshold), triggering the sensing switch unit 32 to be turned on. Thus, the first switch Q1 is triggered to be turned on to heat the first resistor R1, and the fuse 310 is blown to prevent the battery cell 200 from continuing to discharge and causing dangerous accidents such as fire and explosion.

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 following steps:

Step S1 : when the sensing switch unit is triggered to be turned on and the first protection unit does not cut off the power supply circuit, control the second protection unit to protect the battery cell unit.

In this 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 , and the battery protection circuit 300 is electrically connected to the battery cell unit 200 and the external port 500 . A power supply loop is formed therebetween. 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 off 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 circuit works normally. If the first protection unit 30 in the power supply circuit 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 cut off the power supply circuit. When the cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the cell temperature rises to a threshold value or the cell is thermally expanded or the cell is thermally squeezed), the sensing switch unit 32 is triggered to be turned on to The second protection unit is controlled to protect the battery cell unit. That is, the first switch Q1 in the second protection unit is triggered to be turned on to heat the first resistor, fuse the fuse, and disconnect the power supply circuit, so as to avoid continuous charging or discharging, and prevent the cell unit 200 from catching fire. Or explode.

Step S2 : when the sensing switch unit 32 is turned on, the first protection unit 30 does not cut off the power supply circuit, and the third protection unit 33 does not trigger the second protection unit 31 , control the second protection unit 31 to protect the battery cell unit.

In a normal use state, the sensing switch unit 32 is in an off state, and the power supply circuit works normally. And when both the first protection unit 30 and the third protection unit 33 fail. That is, when 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 circuit, and the third protection unit 33 does not trigger the second protection unit 31 . The cell unit 200 is abnormal due to overvoltage or undervoltage (for example, the temperature of the cell rises to a temperature threshold that the sensing switch unit can withstand, or the thermal expansion of the cell exceeds the magnitude threshold or the power The pressure of the core being heated and squeezed is greater than the pressure threshold), the sensing switch unit 32 is triggered to conduct, thereby triggering the conduction of the first switch Q1 to heat the first resistor R1, and the fuse 310 is blown to protect the The battery cell unit 200 can avoid accidents such as fire and explosion.

In one embodiment, the method further includes: 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, triggering the first battery Two protection units 31 protect the battery cells.

In one embodiment, when the battery management system 400 controls the battery cell 200 to discharge at a preset current (eg, 3C-6C current continues to discharge), the fuse 310 cannot be blown. That is, the battery management system 400 controls the battery cell 200 to discharge continuously at a current close to the rated current of the fuse 310 . The battery cell 200 is abnormal due to continuous high-rate discharge (for example, the temperature of the battery cell rises to a temperature threshold that the sensing switch unit can withstand, or the thermal expansion of the battery cell exceeds the threshold value, or the pressure of the thermal extrusion of the battery cell is greater than pressure threshold), triggering the sensing switch unit 32 to be turned on. Thus, the first switch Q1 is triggered to be turned on to heat the first resistor R1, and the fuse 310 is blown to prevent the battery cell 200 from continuing to discharge and causing dangerous accidents such as fire and explosion. 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.

In the battery protection circuit 300 and the battery management system 400 provided with the battery protection circuit 300 provided by the above-mentioned embodiments, the sensing switch unit 32 is arranged at the preset position of the battery cell unit 200 , and the sensing switch unit 32 It is electrically connected to the second protection unit 31, and if the first protection unit 30 does not trigger the second protection unit 31 and the sensing switch unit 32 is triggered and turned on, the second protection unit 32 is controlled. The unit 31 protects the cell unit 200 . The present application can effectively avoid the fire and explosion accident of the battery cell 200 caused by overcharging, overdischarging or discharging at a high rate close to the rated current of the fuse 310 in the case of a single point failure of the battery management system 400 . The battery protection circuit 300 provided by the present application has the advantages of high safety, wide application range, and low cost.

Those of ordinary skill in the art should realize that the above embodiments are only used to illustrate the present application, rather than being used to limit the present application, as long as the above embodiments are appropriate within the scope of the essential spirit of the present application Variations and variations are within the scope of the claims of this application.

Claims (14)

1. A battery protection circuit, characterized in that, the battery protection circuit is electrically connected between a battery cell unit and an external port to form a power supply circuit, and the battery protection circuit includes a first protection unit, a second protection unit and a sensor. test switch unit; the first protection unit is electrically connected between the battery cell unit and the second protection unit; the sensing switch unit is disposed at a preset position of the battery cell unit, and the sensing switch unit is electrically connected to the second protection unit; and When the sensing switch unit is triggered and turned on, and the first protection unit does not cut off the power supply circuit, the second protection unit is controlled to protect the battery cell unit. 2 . The battery protection circuit according to claim 1 , wherein the second protection unit comprises a fuse, a first resistor and a first switch, and the first end of the fuse is used for connecting with the battery cell unit. 3 . The positive pole is electrically connected, the second end of the fuse is electrically connected to the second end of the first switch through the first resistor, and the third end of the fuse is electrically connected to the positive pole of the external port; The first end of the first switch is electrically connected to the sensing switch unit, the second end of the first switch is grounded, and the third end of the first switch is electrically connected to the second end of the fuse connect. 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 battery cell unit exceeds a preset temperature, triggering the The temperature switch is turned on, thereby triggering the first switch to be turned on to heat the first resistor and blow the fuse to protect the battery cell unit. 4 . The battery protection circuit according to claim 2 , wherein the sensing switch unit is a micro switch, and if the battery cell unit is squeezed due to thermal expansion, the micro switch is triggered to be turned on, 5 . Thus, the first switch is triggered to be turned on to heat the first resistor, and the fuse is blown to protect the cell unit. 5 . The battery protection circuit according to claim 1 , wherein the battery protection circuit further comprises a third protection unit, and the third protection unit is electrically connected to the battery cell unit and the second protection unit. 6 . between. 6 . The battery protection circuit of claim 5 , wherein when the sensing switch unit is triggered and turned on, the first protection unit does not turn off the power supply circuit and the third protection unit is not triggered. 7 . In the case of the second protection unit, the second protection unit is controlled to protect the battery cell unit. 7 . A battery management system, characterized in that, the battery management system comprises the battery protection circuit according to any one of claims 1 to 6 . 8 . The battery management system according to claim 7 , wherein when the battery management system controls the battery cell unit to discharge at a preset current, if the sensing switch unit is turned on, all The second protection unit protects the battery cell unit. 9 . The battery management system of claim 8 , wherein the second protection unit comprises a fuse, and a difference between the rated current of the fuse and the preset current is less than or equal to a current threshold. 10 . 10. A battery device comprising a battery cell, characterized in that the battery device further comprises the battery protection circuit according to any one of claims 1 to 6, the battery protection circuit being used to protect the battery cell. 11. A control method for a battery device, the battery device comprising a battery cell unit and a battery protection circuit electrically connected to the battery cell unit, wherein the battery protection circuit is electrically connected to the battery 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, and the method includes: When the sensing switch unit is triggered and turned on, and the first protection unit does not cut off the power supply circuit, the second protection unit is controlled to protect the battery cell unit. 12 . The control method of a battery device according to claim 11 , wherein the battery protection circuit further comprises a third protection unit, and the third protection unit is electrically connected to the battery cell unit and the second protection unit. 13 . Between the protection units, the method further includes: When the sensing switch unit is triggered to be turned on, the first protection unit does not cut off the power supply circuit, and the third protection unit does not trigger the second protection unit, the second protection unit is controlled The unit protects the cell unit. 13. The control method of a battery device according to claim 11, wherein the battery device comprises a battery management system, wherein the method further comprises: 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 turned on, the second protection unit is controlled to protect the battery cell unit. 14 . The method for controlling a battery device according to claim 13 , wherein the second protection unit comprises a fuse, and a difference between the rated current of the fuse and the preset current is less than or equal to a current threshold. 15 .

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