Battery protection circuit and battery device

Abstract

The utility model discloses a battery protection circuit and a battery device, the battery protection circuit comprises a second protection module, the second protection module comprises a double-end fuse, a switch unit and a control unit, a first end of the double-end fuse is configured to be connected with a positive electrode of a battery, and a second end of the double-end fuse is configured to be connected with a negative electrode of the battery; the second end of the double-end fuse is configured to be connected with the first end of a charger or a load and the input end of the switch unit, the output end of the switch unit is configured to be connected with the negative electrode of the battery and the second end of the charger or the load, and the control end of the switch unit is connected with the control unit. When the switch unit is in an off state, the acquisition end of the control unit is connected with the anode and cathode of the battery to acquire battery voltage; the control unit controls the switch unit to be closed when the collected battery voltage exceeds the set voltage. The second protection module adopts the double-end fuse, the switch unit and the control unit to replace a three-end fuse, the manufacturing cost is lower, and the size is smaller.

Description

TECHNICAL FIELD

[0001] The present technology relates to the field of battery protection, in particular to a battery protection circuit and a battery device. BACKGROUND

[0002] The existing lithium battery protection circuit includes a battery, a charger or a load, a primary protection module and a secondary protection module. The primary protection module and the secondary protection module are both used to protect the lithium battery. In the case that the primary protection module cannot work to protect the lithium battery, the secondary protection module is started to protect the battery, so as to prevent the lithium battery system from catching fire or exploding. The existing secondary protection module mostly uses a three-terminal fuse. However, there is a lack of three-terminal fuses with large current on the market at present. The three-terminal fuse has high cost and small working current. In production, the operation of employees is easy to burn out due to slight negligence, and the operation efficiency and yield are low. At the same time, the three-terminal fuse with slightly large current (more than 30A) has a large volume, which occupies a large space of the PCB, and is not conducive to the miniaturization of the circuit board. On the contrary, there are many two-terminal fuses with large current, and the volume of the two-terminal fuse with 30-60A is not large, and the cost is less than half of that of the three-terminal fuse. CONTENT OF THE UTILITY MODEL

[0003] The present application aims to provide a battery protection circuit and a battery device, which can solve the problems of high cost and large volume of the three-terminal fuse in the background technology.

[0004] To achieve the above-mentioned purpose, the present application provides a battery protection circuit, which comprises a second protection module, the second protection module comprises a two-terminal fuse, a switching unit and a control unit, a first end of the two-terminal fuse is configured to be connected to a positive electrode of a battery, a second end of the two-terminal fuse is configured to be connected to a first end of a charger or a load and an input end of the switching unit, an output end of the switching unit is configured to be connected to a negative electrode of the battery and a second end of the charger or the load, a control end of the switching unit is connected to the control unit, when the battery protection circuit is in normal working current, the switching unit is in an open state, and a collection end of the control unit is connected to the positive electrode and the negative electrode of the battery to collect a battery voltage; when the collected battery voltage exceeds a set voltage, the control unit controls the switching unit to be closed.

[0005] The second protection module of the application is in the normal working current of the battery protection circuit, the switch unit is in the open state, the acquisition end of the control unit is connected to the positive and negative poles of the battery to collect the battery voltage; when the collected battery voltage exceeds the set voltage, the control unit controls the switch unit to close, promotes the increase of the current flowing through the double-end fuse, so that the double-end fuse is burned off faster, thereby protecting the circuit and realizing the overvoltage protection of the battery during charging. In addition, when the current of the double-end fuse exceeds the burning current of the double-end fuse, the double-end fuse will be burned off, realizing the overcurrent protection of the battery. The second protection module of the application adopts a double-end fuse, a switch unit and a control unit to replace a three-terminal fuse, which is lower in cost and smaller in size.

[0006] Optionally, the second protection module further comprises a thermistor, two ends of the thermistor being connected to another acquisition end of the control unit;

[0007] The thermistor is used to detect the temperature of the double-end fuse, and when the resistance value signal of the thermistor is greater than a preset resistance value, the control unit controls the switch unit to close.

[0008] Optionally, the thermistor is a negative temperature coefficient thermistor.

[0009] Optionally, the thermistor is fixedly attached to the double-end fuse.

[0010] Optionally, the thermistor is fixedly attached to the double-end fuse by thermal conductive glue.

[0011] Optionally, the thermistor is a negative temperature coefficient thermistor, and the preset resistance value is greater than the resistance value of the thermistor when the double-end fuse is burned off; or,

[0012] The thermistor is a positive temperature coefficient thermistor, and the preset resistance value is less than the resistance value of the thermistor when the double-end fuse is burned off.

[0013] Optionally, the switch unit comprises a first resistor and a first switch tube, a first end of the first resistor being connected to a second end of the double-end fuse, a second end of the first resistor being connected to an input end of the first switch tube, an output end of the first switch tube being connected to a negative pole of the battery, and a control end of the first switch tube being connected to the control unit; when the collected battery voltage exceeds the set voltage, the control unit controls the first switch tube to close.

[0014] Optionally, the maximum working current of the switch unit is 1.2 to 1.5 times the burning current of the double-end fuse.

[0015] Optionally, a first protection module configured to be connected in series between the battery and the charger or the load is further included, a first end of the first protection module is connected to a second end of the charger or the load, and a second end of the first protection module is connected to the negative electrode of the battery.

[0016] To achieve the above object, the application further provides a battery device comprising the battery protection circuit. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A circuit diagram of the battery protection circuit of the embodiment of the application.

[0018] Figure 2 A circuit diagram of the existing battery protection circuit. DETAILED DESCRIPTION

[0019] To illustrate the technical content, structural features, achieved objects and effects of the application, the following will be described in detail in combination with the embodiments and the accompanying drawings.

[0020] Please refer to Figure 2 The existing battery protection circuit comprises a first protection module B1 and a second protection module B2. The first protection module B1 and the second protection module B2 are used to protect the battery V1. In the case that the first protection module B1 cannot work to protect the battery V1, the system will start the second protection module B2 to protect the circuit. The second protection module B2 comprises a three-terminal fuse S1, a second protection chip A1 and a switch tube P1. The first end of the three-terminal fuse S1 is connected to the positive electrode of the battery V1, the second end of the three-terminal fuse S1 is connected to the first end of the charger D1 or the load D1, and the third end of the three-terminal fuse S1 is connected to the first end of the switch tube P1. The second end of the switch tube P1 is connected to the negative electrode of the battery V1, the third end of the switch tube P1 is connected to the second protection chip A1, and the switch tube P1 controls whether the first end and the second end thereof are conductive according to the signal received by the third end thereof. The collection end of the second protection chip A1 is connected to the positive electrode and the negative electrode of the battery V1 respectively, for collecting the voltage between the two ends of the battery V1. The two ends of the first protection module B1 are connected to the second end of the charger D1 or the load D1 and the negative electrode of the battery V1 respectively.

[0021] Specifically, the three-terminal fuse S1 includes a first two-terminal fuse S11, a second two-terminal fuse S12 and a heater S13. The first end of the first two-terminal fuse S11 is connected to the positive pole of the battery V1, the second end of the first two-terminal fuse S11 is connected to the first end of the second two-terminal fuse S12 and the first end of the heater S13, the second end of the second two-terminal fuse S12 is connected to the first end of the charger D1 or the load D1, and the second end of the heater S13 is connected to the first end of the switch tube P1. When the current flowing through the secondary protection module B2 is too large, the first two-terminal fuse S11 and / or the second two-terminal fuse S12 will be fused, and after the battery V1 is overcharged, the secondary protection chip A1 detects that the total voltage of the circuit is too high, thereby controlling the switch tube P1 to be closed, and the heater S13 starts to heat to make the first two-terminal fuse S11 and / or the second two-terminal fuse S12 be fused, so as to achieve the purpose of protecting the battery V1. However, because the circuit composed of the first two-terminal fuse S11, the second two-terminal fuse S12 and the heater S13 occupies a large volume and has a small working current, in production, the operation of the employees is easy to burn the three-terminal fuse S1 if not careful, and therefore the existing three-terminal fuse S1 has low operation efficiency and yield.

[0022] For this purpose, please refer to Figure 1 The battery protection circuit 100 disclosed in the present application includes a second protection module M2, the second protection module M2 includes a two-terminal fuse S2, a switch unit K1 and a control unit C1, the first end of the two-terminal fuse S2 is configured to be connected to the positive pole of the battery V1, the second end of the two-terminal fuse S2 is configured to be connected to the first end of the charger D1 or the load D1 and the input end of the switch unit K1, the output end of the switch unit K1 is configured to be connected to the negative pole of the battery V1 and the second end of the charger D1 or the load D1, the control end of the switch unit K1 is connected to the control unit C1, when the battery protection circuit 100 is in a normal working current, the switch unit K1 is in an open state, and the collection end of the control unit C1 is connected to the positive pole and the negative pole of the battery V1 to collect the voltage of the battery V1; when the collected voltage of the battery V1 exceeds a set voltage, the control unit C1 controls the switch unit K1 to be closed.

[0023] When the battery protection circuit 100 is in normal working current, the switch unit K1 is in an open state, and the collection end of the control unit C1 is connected to the positive and negative poles of the battery V1 to collect the voltage of the battery V1; when the collected voltage of the battery V1 exceeds the set voltage, the control unit C1 controls the switch unit K1 to be closed (the total resistance in parallel is smaller than the resistance value of the switch unit K1 and the resistance value of the charger D1 or the load D1), so as to promote the increase of the current flowing through the double-end fuse S2, so that the double-end fuse S2 is burned off faster, and the overvoltage protection of the battery V1 during charging is realized. In addition, when the current of the double-end fuse S2 exceeds the burning current of the double-end fuse S2, the double-end fuse S2 will be burned off, and the overcurrent protection of the battery V1 is realized. The second protection module M2 of the application can replace the three-terminal fuse with the double-end fuse S2, the switch unit K1 and the control unit C1, which is lower in cost and smaller in size.

[0024] Please refer to Figure 2 The existing battery protection circuit does not have the function of actively monitoring the temperature of the three-terminal fuse S1, and cannot actively pull off the three-terminal fuse S1 to achieve the purpose of protecting the battery V1 by precisely controlling the temperature of the three-terminal fuse S1. However, in actual work, the current through the fuse may have approached the burning current of the fuse, but at this time, the fuse will not be burned off because the current has not reached the burning current value. However, if the current is high for a long time, the heat of the fuse will accumulate, and the system will be in a state of high temperature, and the circuit is also easy to be damaged, at this time, the fuse should be actively pulled off.

[0025] For this purpose, please refer to Figure 1 In some embodiments, the second protection module M2 further comprises a thermistor N1, and the two ends of the thermistor N1 are respectively connected to another collection end of the control unit C1, which is used to collect the resistance value signal of the thermistor N1. The thermistor N1 is used to detect the temperature of the double-end fuse S2, and the control unit C1 controls the switch unit K1 to be closed when receiving the resistance value signal of the thermistor N1 greater than the preset resistance value. Compared with the existing battery protection circuit, the battery protection circuit 100 of the application can actively monitor the temperature of the double-end fuse S2, and actively pull off the double-end fuse S2 by precisely controlling the temperature of the double-end fuse S2 to achieve the purpose of protecting the battery V1.

[0026] Specifically, the thermistor N1 is a negative temperature coefficient thermistor N1 (the higher the temperature, the smaller the resistance).

[0027] Specifically, the thermistor N1 is fixed on the double-end fuse S2.

[0028] Optionally, the thermistor N1 is fixed on the double-end fuse S2 by a heat-conducting adhesive.

[0029] Specifically, the thermistor N1 is a negative temperature coefficient thermistor N1, and a preset resistance value is greater than a resistance value of the thermistor N1 when the double-end fuse S2 is burned out; or, the thermistor N1 is a positive temperature coefficient thermistor (the higher the temperature, the greater the resistance), and a preset resistance value is less than a resistance value of the thermistor N1 when the double-end fuse S2 is burned out.

[0030] In some embodiments, the switch unit K1 includes a first resistor R1 and a first switch tube Q1, a first end of the first resistor R1 is connected to a second end of the double-end fuse S2, a second end of the first resistor R1 is connected to an input end of the first switch tube Q1, an output end of the first switch tube Q1 is connected to a negative electrode of the battery V1, and a control end of the first switch tube Q1 is connected to the control unit C1; the control unit C1 controls the first switch tube Q1 to be closed when a collected battery V1 voltage exceeds a set voltage.

[0031] Specifically, a maximum working current of the switch unit K1 is 1.2 to 1.5 times of a burning current of the double-end fuse S2. It can be understood that, in order to ensure that the battery V1 can work normally, when designing the battery V1 system, selecting a suitable resistance value for the resistor in advance can limit the maximum working current flowing through the first switch tube Q1 so that the first switch tube Q1 will not be damaged, and can also ensure that the double-end fuse S2 will be burned out after the first switch tube Q1 is connected.

[0032] Optionally, the first switch tube Q1 is a metal-oxide semiconductor field effect transistor (MOSFET) tube, but is not limited thereto, and can also be an IGBT module, which is a technical means known to those skilled in the art and will not be described here.

[0033] In some embodiments, the battery protection circuit 100 further includes a first protection module M1 configured to be connected in series between the battery V1 and the charger D1 or the load D1, a first end of the first protection module M1 is connected to a second end of the charger D1 or the load D1, and a second end of the first protection module M1 is connected to a negative electrode of the battery V1.

[0034] Optionally, the second protection module M2 is a secondary protection circuit, and the first protection module M1 is a primary protection circuit. In a normal case, the battery V1 is protected by the first protection module M1, but when the first protection module M1 fails, the second protection module M2 works instead of the first protection module M1. Of course, it is not limited thereto, for example, the second protection module M2 and the first protection module M1 can simultaneously protect the battery V1, and the second protection module M2 does not have to work until the first protection module M1 fails.

[0035] Specifically, the first protection module M1 includes a battery protection chip A2, a second switch Q2 and a third switch Q3. Wherein, the battery V1, the second switch Q2, the third switch Q3 and the charger D1 or the load D1 are configured to be connected in series, the first end of the second switch Q2 is configured to be connected to the negative electrode of the battery V1, the second end of the second switch Q2 is connected to the first end of the third switch Q3, and the second end of the third switch Q3 is configured to be connected to the second end of the charger D1 or the load D1. The battery protection chip A2 is connected to the third end of the second switch Q2 and the third end of the third switch Q3 to control the opening and closing of the second switch Q2 and the third switch Q3.

[0036] Optionally, the second switch Q2 and the third switch Q3 are MOSFET tubes, of course, not limited to this, but also can be IGBT modules and the like, which are well known to those skilled in the art, and will not be repeated here.

[0037] In some embodiments, the control unit C1 is a single-chip microcomputer (MCU). Of course, it is not limited to this, but also can be an FPGA chip and the like.

[0038] The application also discloses a battery device comprising the battery protection circuit 100 as described above.

[0039] Optionally, the battery V1 is a lithium battery.

[0040] The above disclosure is only a preferred example of the application, which cannot limit the scope of the application, so the equivalent changes made according to the claims of the application are all within the scope of the application.

Claims

1. A battery protection circuit, characterized by, The second protection module comprises a double-end fuse, a switch unit and a control unit, a first end of the double-end fuse is configured to be connected to a positive pole of a battery, a second end of the double-end fuse is configured to be connected to a first end of a charger or a load and an input end of the switch unit, an output end of the switch unit is configured to be connected to a negative pole of the battery and a second end of the charger or the load, a control end of the switch unit is connected to the control unit, the switch unit is in an open state when the battery protection circuit is in a normal working current, and the control unit is connected to the positive pole and the negative pole of the battery to collect a battery voltage; the control unit controls the switch unit to be closed when the collected battery voltage exceeds a set voltage.

2. The battery protection circuit of claim 1, wherein, The second protection module further comprises a thermistor, two ends of the thermistor are respectively connected to another collecting end of the control unit. The thermistor is used to detect a temperature of the double-end fuse, and the control unit controls the switch unit to be closed when a resistance value signal of the thermistor is greater than a preset resistance value.

3. The battery protection circuit of claim 2, wherein, The thermistor is a negative temperature coefficient thermistor.

4. The battery protection circuit of claim 2 or 3, wherein the first and second comparators are configured to compare the voltage at the first node to a first threshold voltage and a second threshold voltage, respectively. The thermistor is fixed on the double-end fuse in a pasting manner.

5. The battery protection circuit of claim 4, wherein, The thermistor is fixed on the double-end fuse in a pasting manner through a heat-conducting adhesive.

6. The battery protection circuit of claim 2, wherein The thermistor is a negative temperature coefficient thermistor, and the preset resistance value is greater than a resistance value of the thermistor when the double-end fuse is burnt out; or The thermistor is a positive temperature coefficient thermistor, and the preset resistance value is less than the resistance value of the thermistor when the double-end fuse is burnt out.

7. The battery protection circuit of claim 1, wherein, The switch unit comprises a first resistor and a first switch tube, a first end of the first resistor is connected to the second end of the double-end fuse, a second end of the first resistor is connected to an input end of the first switch tube, an output end of the first switch tube is connected to the negative pole of the battery, and a control end of the first switch tube is connected to the control unit; the control unit controls the first switch tube to be closed when the collected battery voltage exceeds the set voltage.

8. The battery protection circuit of claim 7, wherein, A maximum working current of the switch unit is 1.2 to 1.5 times of a burnt-out current of the double-end fuse.

9. The battery protection circuit of claim 1, wherein, A first protection module configured to be connected in series between the battery and the charger or the load is further included, a first end of the first protection module is connected to the second end of the charger or the load, and a second end of the first protection module is connected to the negative pole of the battery.

10. A battery device characterized by comprising: The battery protection circuit comprises the battery protection circuit according to any one of claims 1 to 9.

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