Self-resetting fuse, battery protection circuit and control method thereof

Abstract

The application relates to the field of electronic technology and discloses a self-recovery fuse, a battery protection circuit and a control method thereof, which comprises the following steps: the self-recovery fuse comprises two PPTC electrodes, a high-molecular matrix material filled between the two PPTC electrodes and conductive microparticles, and the self-recovery fuse further comprises a heating element and a heating element electrode; the heating element electrode is a controllable electrode and is connected in series in a power supply loop of the heating element, wherein the heating element is adjacent to or abuts against the high-molecular matrix material; the heating element generates heat for heating the high-molecular matrix material when the controllable electrode is in a conduction state. The application makes the heating element generate corresponding heat to disconnect the self-recovery fuse when the heating element electrode is turned on, thereby realizing active controllable protection of the self-recovery fuse PPTC and having the remarkable advantages of perfect control function and reliable protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronics, in particular to a self-recovery fuse, a battery protection circuit and a control method thereof. BACKGROUND

[0002] The self-recovery fuse, in English abbreviation PPTC (Polymer Positive Temperature Coefficient, polymer positive temperature coefficient thermistor), is a passive protection device with automatic recovery function composed of high molecular matrix material and conductive particles, including plug-in PPTC and patch PPTC. The working principle of PPTC is: when there is an abnormal overcurrent passing through PPTC, the heat generated causes the high molecular matrix material to expand, and the conductive particles wrapped outside the high molecular matrix material will separate to cut off the conductive channel of PPTC, so that the resistance of the self-recovery fuse rises, thereby reducing the abnormal overcurrent and protecting the circuit equipment from damage; when the abnormal overcurrent fault is cleared, the high molecular matrix material of the self-recovery fuse shrinks to its original shape to reconnect the conductive particles, and the conductive channel of PPTC will recover, and the resistance of the self-recovery fuse will also return to the original low resistance state; this process can be repeated many times. Compared with the traditional fuse which needs to be replaced after overcurrent protection, PPTC can automatically recover after triggering disconnection and be reused, so it is widely used in consumer electronics, computer peripherals, power tools, electric vehicles, medical devices and industrial equipment, etc. to protect the circuit from the influence of electrical faults such as overload, short circuit and overvoltage.

[0003] Currently, the protection circuit containing small patch PPTC can only be passively disconnected when the current exceeds the rated specification, and cannot actively control its disconnection when needed. Therefore, the existing PPTC control function is relatively simple, it is difficult to achieve active controllable protection of PPTC, and there are defects of imperfect control function and unreliable protection. SUMMARY

[0004] Therefore, the present application provides a self-recovery fuse, a battery protection circuit and a control method thereof to solve the problem of single control function of the existing PPTC, difficulty in achieving active controllable protection of PPTC, and imperfect control function and unreliable protection.

[0005] In a first aspect, the present application provides a self-recovery fuse, the self-recovery fuse comprising two PPTC electrodes and a high molecular matrix material and conductive particles filled between the two PPTC electrodes, the self-recovery fuse further comprising: a heating element and a heating element electrode;

[0006] The heating element electrode is a controllable electrode, which is connected in series in the power supply circuit of the heating element, wherein the heating element is adjacent to or abuts the high molecular matrix material;

[0007] The heating element generates heat for heating the polymer matrix material when the controllable electrode is in the on state.

[0008] The heating element generates heat for heating the polymer matrix material when the controllable electrode is in the on state.

[0009] In an alternative embodiment, one end of the heating element is connected to any PPTC electrode, and the other end is connected to the heating element electrode; one end of the heating element electrode is connected to the heating element, and the other end is connected to the external control unit and then connected to the other PPTC electrode, for controlling the working state of the heating element electrode to be in the on state according to the external control instruction of the external control unit, controlling the heating element to generate corresponding heat to make the self-recovery fuse break to realize active controllable protection.

[0010] The heating element generates heat for heating the polymer matrix material when the controllable electrode is in the on state.

[0011] In an alternative embodiment, the heating element is a heating resistor layer, and the heating element electrode is a heating resistor electrode.

[0012] In a second aspect, the application provides a battery protection circuit, which comprises a battery and its positive and negative electrodes, a battery protection control unit, and an output unit, one end of the battery protection control unit is connected to any electrode of the positive and negative electrodes of the battery, and the other end is connected to the output unit, the battery protection circuit further comprises a self-recovery fuse and an external control unit, the self-recovery fuse is the self-recovery fuse according to the first aspect or any of the alternative embodiments thereof.

[0013] In an alternative embodiment, one end of the heating element is connected to any PPTC electrode, and the other end is connected to the heating element electrode; one end of the heating element electrode is connected to the heating element, and the other end is connected to the external control unit and then connected to the other PPTC electrode, for controlling the working state of the heating element electrode to be in the on state according to the external control instruction of the external control unit, controlling the heating element to generate corresponding heat to make the self-recovery fuse break to realize active controllable protection.

[0014] The external control unit generates an external control instruction for controlling the working state of the heating element electrode to be in the conducting state, controlling the heating element to generate corresponding heat, and disconnecting the self-restoring fuse to realize active controllable protection.

[0015] In an alternative embodiment, the battery protection control unit comprises a first switching device and a first control device, and the first switching device and the first control device are connected, wherein the first control device is configured to acquire state parameters of the battery in the battery protection circuit, state information of the first switching device and the first control device, generate an internal control instruction based on the state parameters and the state information, and control the opening and closing state of the first switching device based on the internal control instruction.

[0016] The battery protection control unit comprising the first switching device and the first control device is designed to realize basic circuit protection of the battery protection circuit.

[0017] In an alternative embodiment, the external control unit comprises a second switching device and a second control device, and the second switching device and the second control device are connected, wherein the second control device is configured to acquire state parameters of the battery in the battery protection circuit, generate an external control instruction based on the state parameters, and control the opening and closing state of the second switching device based on the external control instruction.

[0018] The external control unit comprising the second switching device and the second control device is designed to realize active controllable protection of the self-restoring fuse, and realize more diverse protection of the battery protection circuit, so as to make the function of the battery protection circuit more perfect and the protection more reliable.

[0019] In a third aspect, the application provides a control method of a battery protection circuit, which is applied to the battery protection circuit of the second aspect or any of the alternative embodiments thereof, and the control method comprises:

[0020] acquiring first state information of the battery protection control unit and second state information of the external control unit;

[0021] determining a current protection mode of the battery protection circuit and a corresponding protection control strategy based on the first state information and the second state information, and controlling the battery protection circuit to execute the protection control strategy.

[0022] The control method of the battery protection circuit of the application analyzes the first state information of the battery protection control unit and the second state information of the external control unit, determines the current protection mode of the battery protection circuit and the corresponding protection control strategy and controls the battery protection circuit to execute the corresponding protection control strategy, so as to realize the controllable protection of PPTC and make the control function of the battery protection circuit more perfect and the protection more reliable.

[0023] In an alternative embodiment, the first state information of the battery protection control unit is obtained, comprising:

[0024] The current state parameter of the battery and the state information of the first switching device and the first control device are obtained.

[0025] It is determined whether the current state parameter is greater than a preset first parameter threshold and whether the state information is abnormal.

[0026] When the current state parameter is not greater than the preset first parameter threshold or the state information is abnormal, the internal control instruction for controlling the first switching device to be in a closed state is generated.

[0027] When the current state parameter is greater than the preset first parameter threshold, the internal control instruction for controlling the first switching device to be in an open state is generated.

[0028] The internal control instruction is determined as the first state information of the battery protection control unit.

[0029] The first state information of the battery protection control unit is determined by the size determination of the current state parameter of the battery and the preset first parameter threshold and the abnormality determination of the state information of the first switching device and the first control device, which can guarantee the acquisition quality of the first state information, help to improve the control accuracy of the battery protection circuit and make the control function more perfect and the protection more reliable.

[0030] In an alternative embodiment, the second state information of the external control unit is obtained, comprising:

[0031] The current state parameter of the battery is obtained.

[0032] It is determined whether the current state parameter is greater than a preset second parameter threshold, wherein the preset second parameter threshold is greater than the preset first parameter threshold.

[0033] When the current state parameter is not greater than the preset second parameter threshold, the external control instruction for controlling the second switching device to be in an open state is generated.

[0034] When the current state parameter is greater than the preset second parameter threshold, the external control instruction for controlling the second switching device to be in a closed state is generated.

[0035] The external control instruction is determined as second state information of the external control unit.

[0036] The second state information is determined by judging the size of the current state parameter of the battery and the preset second parameter threshold, which not only guarantees the acquisition quality of the second state information, but also realizes the active controllable protection of the PPTC, so that the control function of the battery protection circuit is more perfect and the protection is more reliable.

[0037] In an optional embodiment, the current protection mode of the battery protection circuit and the corresponding protection control strategy are determined based on the first state information and the second state information, including:

[0038] It is respectively judged whether the first switch device in the internal control instruction is in a closed state and whether the second switch device in the external control instruction is in a closed state;

[0039] When the first switch device is in a closed state and the second switch device is in an open state, it is determined that the current protection mode of the battery protection circuit is only an internal protection mode, and the internal control instruction is determined as the protection control strategy;

[0040] When the first switch device is in an open state and the second switch device is in a closed state, it is determined that the current protection mode of the battery protection circuit is only an external protection mode, and the external control instruction is determined as the protection control strategy;

[0041] When the first switch device is in a closed state and the second switch device is in a closed state, it is determined that the current protection mode of the battery protection circuit is an internal and external coexistence protection mode, and the internal control instruction and the external control instruction are determined as the protection control strategy;

[0042] When the first switch device is in an open state and the second switch device is in an open state, the steps of acquiring the first state information of the battery protection control unit and the second state information of the external control unit are returned.

[0043] The current protection mode of the battery protection circuit and the corresponding protection control strategy are determined by judging whether the first switch device in the internal control instruction is in a closed state and whether the second switch device in the external control instruction is in a closed state, which helps to perfect the control function of the battery protection circuit and further guarantees the reliability of the protection. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to make the technical solutions in the embodiment of the present application or prior art clearer, the accompanying drawings needed in the description of the embodiment or prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 is a structural schematic diagram of a self-resetting fuse according to an embodiment of the present application;

[0046] Figure 2 is a structural schematic diagram of another self-resetting fuse according to an embodiment of the present application;

[0047] Figure 3 is a normal state schematic diagram of a conventional self-resetting fuse;

[0048] Figure 4 is an expanded and disconnected state schematic diagram of a conventional self-resetting fuse;

[0049] Figure 5 is a sectional view of a self-resetting fuse according to an embodiment of the present application;

[0050] Figure 6 is a bottom view of a self-resetting fuse according to an embodiment of the present application;

[0051] Figure 7 is a structural schematic diagram of a battery protection circuit according to an embodiment of the present application;

[0052] Figure 8 is a structural schematic diagram of a conventional battery protection circuit;

[0053] Figure 9 is a structural schematic diagram of another battery protection circuit according to an embodiment of the present application;

[0054] Figure 10 is a flowchart of a control method of a battery protection circuit according to an embodiment of the present application;

[0055] Figure 11 is a flowchart of a control method of another battery protection circuit according to an embodiment of the present application. EMBODIMENT

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] This embodiment provides a self-resetting fuse. Figure 1 This is a schematic diagram of the structure of a self-resetting fuse according to an embodiment of the present invention, as shown below. Figure 1 As shown, the self-resetting fuse includes: two PPTC electrodes 101 and a polymer matrix material 102 and conductive particles 103 filling the space between the two PPTC electrodes. The self-resetting fuse also includes: a heating element 104 and a heating element electrode 105; the heating element electrode 105 is a controllable electrode, which is connected in series in the power supply circuit of the heating element 104, wherein the heating element 104 is adjacent to or abuts the polymer matrix material 102; when the controllable electrode is in the conducting state, the heating element 104 generates heat for heating the polymer matrix material.

[0058] It should be noted that a conventional resettable fuse consists of two PPTC electrodes 101 forming a power supply circuit. In this embodiment, when a heating element 104 is added to a conventional resettable fuse, the power supply circuit for the heating element 104 consists of the two PPTC electrodes 101 and the heating element 104. Specifically, by adding a heating element 104 and heating element electrodes 105 to the resettable fuse, the heating element 104 generates heat corresponding to the polymer matrix material 102 when the controllable electrode is in the conducting state, causing the resettable fuse to expand and thus disconnect. This achieves the purpose of controllable disconnection of the resettable fuse, making the PPTC function more complete and the protection more reliable.

[0059] It should be noted that the specific materials of the PPTC electrode 101, the polymer matrix material 102, and the conductive particles 103 in this embodiment are not limited, and are all adapted based on actual needs. For example, the electrodes at both ends of the self-resetting fuse are made of nickel or "copper + tin" to obtain the PPTC electrode 101; the polymer matrix material 102 is a polymer resin; and the conductive particles 103 are metallic conductive particles, which are only used as examples.

[0060] In this embodiment, the specific shape of the self-resetting fuse is adapted based on the actual materials and packaging process, such as flat-head tubular fuses, spiral fuses, blade fuses, surface mount fuses, etc., which are only used as examples.

[0061] This embodiment provides a self-resetting fuse.Figure 2 is a structural schematic diagram of another self-recovery fuse according to an embodiment of the present application, as Figure 2 shown, the heating element 104 in this embodiment is arranged at the bottom position of the self-recovery fuse, one end of which is connected with any PPTC electrode 101, and the other end is connected with the heating element electrode 105. It should be noted that the bottom position of the self-recovery fuse is relative to the cross section or edge of the actual self-recovery fuse corresponding shape, such as for the plug-in fuse, in addition to the pin part, if the shape of the fuse is rectangular, then the bottom position is the bottom edge of the rectangle; if it is a column, then the bottom position is the bottom surface of the column. Specifically, arranging the heating element 104 at the bottom position of the self-recovery fuse facilitates the production of the corresponding heating element electrode of such self-recovery fuse, and guarantees the universality of such self-recovery fuse.

[0062] In this embodiment, the heating element electrode 105 is a controllable electrode, one end of which is connected with the heating element 104, and the other end is connected with the other PPTC electrode 101 after being connected with the external control unit, for controlling the heating element 104 to generate corresponding heat according to the external control instruction of the external control unit, which can make the high molecular matrix material expand under heat, and then make the self-recovery fuse break to realize active controllable protection.

[0063] It should be noted that the specific types of the heating element 104 and the heating element electrode 105 in this embodiment are not limited here and can be adaptively adjusted based on actual needs. Specifically, the heating element is a heating resistance layer, and the heating element electrode is a heating resistance electrode.

[0064] In actual application, the working principle of the conventional self-recovery fuse PPTC is as follows: when there is an over-specification current, i.e. an abnormal overcurrent, passing through the PPTC, a large amount of heat generated by the on-resistance of the PPTC itself will make the high molecular matrix material expand, and the conductive particles wrapped in the high molecular matrix material will be separated due to the expansion and stretching, thereby cutting off the conductive channel of the PPTC to make the resistance of the PPTC rise until the PPTC is broken, thereby blocking the passage of abnormal current. When the abnormal overcurrent disappears, the PPTC no longer generates heat, the high molecular matrix material temperature decreases and shrinks to the original shape, re-connecting the conductive particles and restoring the conductive channel, so that the resistance of the PPTC returns to the original low-resistance normal state. The above process can be repeated many times. Therefore, compared with the one-time use limit of the conventional fuse, the self-recovery fuse PPTC has the dual functions of overcurrent and overheat protection and automatic recovery.

[0065] In a specific embodiment, Figure 3 is a normal state schematic diagram of a conventional self-recovery fuse, Figure 4is a schematic diagram of the expansion open state of the conventional self-recovery fuse. Specifically, the PPTC characteristic is that it presents a low resistance, about several milliohms to several ohms, under normal current conditions; under overcurrent fault, the resistance sharply increases, thereby protecting the rear-end circuit. Since it has excellent recoverable characteristics, when used for overcurrent protection, the circuit can automatically recover to the on state after the fault is eliminated, and its normal state can refer to Figure 3 ; its expansion open state can refer to Figure 4 .

[0066] Since the existing PPTC control function is single, it is difficult to realize active controllable protection of the PPTC, and there are problems of imperfect control function and unreliable protection. The self-recovery fuse in the embodiment of the present application adds a resistance layer with a fixed resistance value at the bottom of the PPTC device. The resistance layer can be connected to an external control circuit, and the resistance layer generates appropriate heat to make the PPTC expand and thereby open, so as to realize the purpose of controllable opening of the PPTC. In the embodiment, the PPTC with the active heating resistance can not only maintain the passive opening characteristics of the original PPTC, but also complete the active opening of the PPTC when the heating of the resistance layer needs to be controlled by the external circuit. The PPTC can realize passive and active controllable protection, so that the function of the PPTC is more perfect, and the protection is more reliable.

[0067] In a specific embodiment, Figure 5 is a sectional view of the self-recovery fuse according to the embodiment of the present application. In the embodiment, a heating resistance layer is added at the bottom of the original PPTC. The resistance value of the heating resistance layer can be customized to a suitable value according to the actual heat generation requirement. For example, the resistance value of the heating resistance layer can be set according to the heat generation requirement Q = I 2 R of the required PPTC opening temperature, and the value is generally set in the range of 0.5-1.5 Ω. In addition, a controllable electrode, i.e., a heating resistance electrode, is led out from the bottom of the PPTC through the heating resistance layer. The other electrode of the heating resistance layer is shared with any one of the two PPTC electrodes. Specifically, Figure 6 is a bottom view of the self-recovery fuse according to the embodiment of the present application. As can be seen from Figure 6 , the left electrode of the heating resistance layer is fused with the left electrode of the PPTC, i.e., the PPTC electrode 601, and the electrodes are shared; the right electrode of the heating resistance layer is independently provided as an electrode, i.e., the heating resistance electrode 603; and the heating resistance electrode 603 is connected to the right electrode of the PPTC, i.e., the PPTC electrode 602.

[0068] The self-recovery fuse of the embodiment of the present application is a PPTC with a heating resistance layer, that is, by adding a heating resistance layer and a heating resistance electrode at the bottom of a conventional PPTC, the heating resistance layer can be connected to an external control unit, and the heating resistance layer generates appropriate heat to make the PPTC expand and break according to the requirement, so that the PPTC realizes active and controllable protection, and the function of the PPTC is more perfect, and the protection is more reliable.

[0069] In the embodiment, a battery protection circuit is provided, Figure 7 is a structural schematic diagram of the battery protection circuit according to the embodiment of the present application, as Figure 7 shown, the battery protection circuit includes a battery 701 and its positive and negative electrodes (wherein the positive electrode of the battery is represented by "+", and the negative electrode of the battery is represented by "-"), a battery protection control unit 702, and an output unit 703, one end of the battery protection control unit 702 is connected to any one of the positive and negative electrodes of the battery, and the other end is connected to the output unit 703, and the battery protection circuit further includes a self-recovery fuse 704 and an external control unit 705.

[0070] In the embodiment, one end (that is, any PPTC electrode) of the self-recovery fuse 704 is connected to the other electrode of the positive and negative electrodes of the battery, and the other end is respectively connected to the output unit 703 and one end of the external control unit 705 (that is, the other PPTC electrode is connected to the output unit 703, and the heating element electrode and one end of the external control unit 705 are connected), and the other end of the external control unit 705 is connected to the battery protection control unit 702.

[0071] In the embodiment, the external control unit 705 generates an external control instruction, which is used to control the working state of the heating element electrode to be in a conduction state, control the heating element to generate corresponding heat, and make the self-recovery fuse 704 break to realize active and controllable protection.

[0072] Specifically, the battery protection circuit of the embodiment of the present application can realize passive and active controllable protection of the self-recovery fuse by designing the self-recovery fuse and the external control unit, so that the protection mode of the battery protection circuit is more diverse, the function is more perfect, and the protection is more reliable.

[0073] In the embodiment, the battery protection control unit 702 comprises a first switching device 7021 and a first control device 7022 connected together, wherein the first control device 7022 is configured to acquire state parameters of the battery 701 in the battery protection circuit, state information of the first switching device 7021 and the first control device 7022, generate internal control instructions based on the state parameters and the state information, and control the on-off state of the first switching device 7021 based on the internal control instructions. Specifically, the battery protection control unit of the first switching device and the first control device is designed to realize the basic circuit protection of the battery protection circuit.

[0074] It should be noted that the state parameters of the battery 701 in the embodiment are not limited here, and can be adjusted adaptively based on actual needs. For example, the state parameters can be voltage, energy, power, etc. of the battery, which are only exemplary.

[0075] In the embodiment, the external control unit 705 comprises a second switching device 7051 and a second control device 7052 connected together, wherein the second control device 7052 is configured to acquire state parameters of the battery 701 in the battery protection circuit, generate external control instructions based on the state parameters, and control the on-off state of the second switching device 7051 based on the external control instructions. Specifically, the external control unit of the second switching device and the second control device is designed to realize active controllable protection of the self-resetting fuse, and more diverse protection of the battery protection circuit is realized to make the function of the battery protection circuit more perfect and the protection more reliable.

[0076] It should be noted that the specific types of the first switching device 7021, the first control device 7022, the second switching device 7051 and the second control device 7052 are not limited here and can be adjusted adaptively based on actual needs. For example, the first switching device 7021 and the second switching device 7051 are both switching devices, such as MOS switches; the first control device 7022 and the second control device 7052 are both control ICs, which are commonly used components of lithium battery protection boards and are used to control the MOS switch to be turned on under normal conditions, so that the battery cell (i.e. lithium battery) communicates with the external circuit (i.e. output unit or load). When the voltage of the battery cell or the current of the circuit exceeds the specified value, it immediately (within tens of milliseconds) controls the MOS switch to be turned off to protect the safety of the battery cell.

[0077] In practical applications, the conventional self-resetting fuse PPTC is widely used in battery protection circuits. The structure diagram of the battery protection circuit based on the conventional PPTC, i.e. the structure diagram of the conventional battery protection circuit, is as follows: Figure 7As shown. Specifically, the PPTC is directly connected in series on the positive or negative path of the lithium battery. If the output end of the circuit is abnormal, i.e. there is an abnormal current exceeding the rated specification of the PPTC; the abnormal current passes through the PPTC, and since the PPTC itself has a certain resistance, the oversized large current will cause the self-resistance of the PPTC to heat up and cause the PPTC to disconnect the output, thereby playing a protective role. Figure 8 It can be seen that the control IC1 is a conventional IC component of the lithium battery protection circuit. Specifically, the control IC1 determines whether the lithium battery is in a safe working range by monitoring the state parameters of the lithium battery and the state parameters of the output unit (i.e. output-), and if it is not in the safe working range, the control switch device 1 is turned on, i.e. the output of the lithium battery is disconnected, so that the lithium battery stops working.

[0078] Based on the single control function of the existing PPTC, it is difficult to realize the active controllable protection of the PPTC. The self-resetting fuse of the embodiment of the present application is applied in the battery protection circuit, i.e. the structure diagram of the battery protection circuit composed of the self-resetting fuse of the embodiment is as shown in Figure 9 Specifically, the PPTC electrode 902 of the embodiment is connected to the positive electrode (i.e. "+") of the lithium battery; the PPTC electrode 901 is connected to one end of the output circuit (i.e. output+); the right electrode (i.e. the heating resistance electrode 903) of the heating resistance layer in the PPTC is connected to a switch device 2, one end of the switch device 2 is connected to the negative electrode (i.e. "-") of the lithium battery; the control end of the switch device 2 is connected to the control IC2; which controls the opening and closing state of the switch device 2 based on the actual application, i.e. when the switch device 2 is closed, the circuit is closed to form a loop, and the heating resistance layer heats up because of the large current, and the heat is conducted to the PPTC to make the PPTC disconnect. Figure 9 It can be seen that when the control IC2 does not participate in control, the PPTC has all the functions and protection effects of the current conventional PPTC. When the control IC2 participates in control, the control IC2 controls the opening and closing of the switch device 2, so that one end of the heating resistance layer in the PPTC is connected to the negative electrode of the lithium battery to form a path, so that the resistance in the heating resistance layer of the PPTC heats up, generates heat, and further causes the PPTC to expand and disconnect, thereby realizing the active control disconnecting function of the PPTC.

[0079] It should be noted that the determination of whether the control IC 2 participates in the control is not limited here and is adaptively set based on actual needs. Specifically, since the control IC 2 is only responsible for controlling the switching device 2, that is, when the control IC 2 detects that the state parameter of the lithium battery, such as the voltage, is higher than the set value V2, the control IC 2 controls the switching device 2 to be closed, so that the heating resistor layer in the PPTC is connected to the circuit to generate heat. The control IC 1 also has the function of controlling the switching device 1 to be opened when the voltage of the lithium battery is higher than the set value V1, but in the setting, V2>V1, that is, during charging, when the voltage of the lithium battery reaches V1, the control IC 1 will control the switching device 1 to be opened, so that the charging circuit is disconnected, and after being disconnected, the voltage of the lithium battery no longer rises to V2, and in this case, the control IC 2 will not act, that is, the control IC 2 will not act. When the control IC 1 or the switching device 1 fails (that is, in a fault state), the battery voltage reaches V1, and the switching device 1 still does not open, and continues to charge the battery, until the battery voltage rises to V2, and the IC 2 controls the switching device 2 to be closed, connecting the heating resistor in the PPTC, and the heating resistor generates heat due to the large current passing through it, and the heat makes the PPTC temperature rise and disconnect, thereby cutting off the charging current and protecting the lithium battery from being charged to a voltage exceeding the limit. After the PPTC is disconnected, the current passing through the heating resistor is through the PPTC, so after the PPTC is disconnected, the heating resistor also has no current, that is, the heating resistor does not generate heat, and the PPTC will restore the conduction after the temperature of the PPTC decreases.

[0080] In summary, the battery protection circuit of the embodiment of the present application can realize passive and active controllable protection of the self-recovery fuse through the design of the self-recovery fuse and the external control unit, so that the protection mode of the battery protection circuit is more diverse, the function is more perfect, and the protection is more reliable.

[0081] In the embodiment of the present application, a control method embodiment of a battery protection circuit is also provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0082] In the embodiment, a control method of a battery protection circuit is provided, Figure 10 is a flowchart of the control method of the battery protection circuit according to the embodiment of the present application, as Figure 10 shown, the flowchart includes the following steps:

[0083] In step S1001, the first state information of the battery protection control unit and the second state information of the external control unit are obtained.

[0084] It should be noted that the control method of the battery protection circuit in the embodiment is applied to the battery protection circuit described above, and the control method of the battery protection circuit is described in detail with reference to Figure 7 In the embodiment, the specific content of the first state information and the second state information is not limited here and is adaptively adjusted based on actual needs. For example, the first state information includes state parameters of the battery, such as voltage, running state data of the first switching device and the first control device, which are only exemplary.

[0085] In step S1002, the current protection mode of the battery protection circuit and the corresponding protection control strategy are determined based on the first state information and the second state information, and the battery protection circuit is controlled to execute the protection control strategy.

[0086] In the embodiment, the specific content of the current protection mode of the battery protection circuit and the corresponding protection control strategy is not limited here and is adaptively adjusted based on actual needs. For example, the current protection mode of the battery protection circuit includes an internal protection mode of a conventional battery protection circuit and an external protection mode combined with the self-recovery fuse of the embodiment, which are only exemplary.

[0087] The control method of the battery protection circuit in the embodiment of the application analyzes the first state information of the battery protection control unit and the second state information of the external control unit, determines the current protection mode of the battery protection circuit and the corresponding protection control strategy, and controls the battery protection circuit to execute the corresponding protection control strategy, thereby realizing passive and active controllable protection of the PPTC and making the control function of the battery protection circuit more perfect and the protection more reliable.

[0088] In the embodiment, a control method of a battery protection circuit is provided, Figure 11 is a flowchart of another control method of a battery protection circuit according to the embodiment of the application, as shown in the figure, the flowchart includes the following steps: Figure 11

[0089] In step S1101, the first state information of the battery protection control unit and the second state information of the external control unit are obtained.

[0090] In the embodiment, the first state information of the battery protection control unit is obtained, including:

[0091] In step A1, the current state parameters of the battery, the state information of the first switching device and the first control device are obtained.

[0092] ​It should be noted that the specific acquisition manner of the current state parameter of the battery, the state information of the first switching device and the first control device in the embodiment is not limited here, and is determined based on the conventional data acquisition manner in the art. For example, the current state parameter of the battery, such as voltage, is read by using a digital multimeter or other electronic test instrument, which is only illustrative.

[0093] Step A2, respectively, determine whether the current state parameter is greater than the preset first parameter threshold and whether the state information is abnormal.

[0094] It should be noted that the specific content and value of the preset first parameter threshold in the embodiment are not limited here, and are adaptively adjusted based on actual needs.

[0095] Step A3, when the current state parameter is not greater than the preset first parameter threshold or the state information is abnormal, the internal control instruction for controlling the first switching device to be in a closed state is generated correspondingly.

[0096] In the embodiment, the detection manner of whether the state information is abnormal is not limited here, and is adaptively adjusted based on actual needs. For example, the appearance and function of the first control device are tested to determine whether it is abnormal; for the first switching device, such as MOS switch, the MOS switch is placed under a microscope to observe whether it is broken and the resistance value of the MOS pin is tested by using a multimeter to see whether it is broken down to determine whether it is abnormal, which is only illustrative.

[0097] Step A4, when the current state parameter is greater than the preset first parameter threshold, the internal control instruction for controlling the first switching device to be in an open state is generated correspondingly.

[0098] Step A5, the internal control instruction is determined as the first state information of the battery protection control unit.

[0099] In the embodiment of the application, the first state information is determined by determining the size of the current state parameter of the battery and the preset first parameter threshold of the battery, in combination with the abnormality determination of the state information of the first switching device and the first control device, which can guarantee the acquisition quality of the first state information, help to improve the control accuracy of the battery protection circuit, and make the control function more perfect and the protection more reliable.

[0100] In the embodiment, the second state information of the external control unit is acquired, including:

[0101] Step B1, acquiring the current state parameter of the battery.

[0102] The acquisition manner of the current state parameter of the battery in the embodiment is determined with reference to the content of step A1 in the foregoing, which is not repeated here.

[0103] Step B2, judging whether the current state parameter is greater than a preset second parameter threshold, wherein the preset second parameter threshold is greater than the preset first parameter threshold.

[0104] In the embodiment, the specific content and value of the preset second parameter threshold are not limited here and are adaptively adjusted based on actual requirements.

[0105] Step B3, when the current state parameter is not greater than the preset second parameter threshold, generating an external control instruction corresponding to controlling the second switching device to be in an open state.

[0106] Step B4, when the current state parameter is greater than the preset second parameter threshold, generating an external control instruction corresponding to controlling the second switching device to be in a closed state.

[0107] Step B5, determining the external control instruction as the second state information of the external control unit.

[0108] The embodiment of the application determines the second state information by judging the size of the current state parameter of the battery and the preset second parameter threshold of the battery, which not only guarantees the acquisition quality of the second state information, but also realizes the active controllable protection of the PPTC, so that the control function of the battery protection circuit is more perfect and the protection is more reliable.

[0109] Step S1102, determining the current protection mode of the battery protection circuit and the corresponding protection control strategy based on the first state information and the second state information, and controlling the battery protection circuit to execute the protection control strategy.

[0110] Specifically, the determination of the current protection mode of the battery protection circuit and the corresponding protection control strategy based on the first state information and the second state information in the above step S1102 includes:

[0111] Step S11021, respectively judging whether the first switching device in the internal control instruction is in a closed state and whether the second switching device in the external control instruction is in a closed state.

[0112] Step S11022, when the first switching device is in a closed state and the second switching device is in an open state, determining that the current protection mode of the battery protection circuit is an internal protection mode only, and determining the internal control instruction as the protection control strategy.

[0113] Step S11023, when the first switching device is in an open state and the second switching device is in a closed state, determining that the current protection mode of the battery protection circuit is an external protection mode only, and determining the external control instruction as the protection control strategy.

[0114] In step S11024, when the first switch device is in the closed state and the second switch device is in the closed state, it is determined that the current protection mode of the battery protection circuit is the internal-external coexistence protection mode, and the internal control instruction and the external control instruction are determined as the protection control strategy.

[0115] In step S11025, when the first switch device is in the open state and the second switch device is in the open state, the step of obtaining the first state information of the battery protection control unit and the second state information of the external control unit is returned.

[0116] In the embodiment of the present application, the current protection mode of the battery protection circuit and the corresponding protection control strategy are determined by judging whether the first switch device in the internal control instruction is in the closed state and whether the second switch device in the external control instruction is in the closed state, which helps to improve the control function of the battery protection circuit and further guarantees the reliability of protection.

[0117] In conclusion, the control method of the battery protection circuit in the embodiment of the present application, based on the battery protection circuit with the PPTC with active heating resistance, not only can maintain the passive opening characteristics of the original PPTC to realize the basic protection function of the battery protection circuit, but also can make the PPTC actively open by controlling the heating of the heating resistance layer through the external circuit when needed, realizing the passive and active controllable protection of the PPTC, making the function of the PPTC more perfect and the protection more reliable.

[0118] Although the embodiments of the present application are described in combination with the drawings, various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A self-restoring fuse comprising two PPTC electrodes and a polymer matrix material and electrically conductive fine particles filled between the two PPTC electrodes, characterized in that, The self-recovery fuse further comprises a heating element and a heating element electrode; The heating element electrode is a controllable electrode, which is connected in series in a power supply loop of the heating element, wherein the heating element is adjacent to or abuts against the high polymer matrix material; The heating element generates heat for heating the high polymer matrix material when the controllable electrode is in a conducting state.

2. The self-restoring fuse according to claim 1, characterized in that One end of the heating element is connected with any one of the PPTC electrodes, and the other end is connected with the heating element electrode; one end of the heating element electrode is connected with the heating element, and the other end is connected with another PPTC electrode after being connected with an external control unit, for controlling the working state of the heating element electrode to be in a conducting state according to an external control instruction of the external control unit, controlling the heating element to generate corresponding heat, and making the self-recovery fuse break to realize active controllable protection.

3. The self-restoring fuse of claim 1, wherein, The heating element is a heating resistance layer, and the heating element electrode is a heating resistance electrode.

4. A battery protection circuit comprising a battery and its positive and negative electrodes, a battery protection control unit, and an output unit, one end of the battery protection control unit being connected to either of the positive and negative electrodes of the battery and the other end being connected to the output unit, characterized in that, The battery protection circuit further comprises a self-recovery fuse and an external control unit, wherein the self-recovery fuse is the self-recovery fuse according to any one of claims 1 to 3; Any one of the PPTC electrodes of the self-recovery fuse is connected with another electrode of the positive and negative electrodes of the battery, the other PPTC electrode is connected with the output unit, one end of the heating element electrode and the external control unit is connected, and the other end of the external control unit is connected with an electrode opposite to the other electrode of the positive and negative electrodes of the battery; The external control unit generates an external control instruction for controlling the working state of the heating element electrode to be in a conducting state, controlling the heating element to generate corresponding heat, and making the self-recovery fuse break to realize active controllable protection.

5. The battery protection circuit of claim 4, wherein, The battery protection control unit comprises a first switching device and a first control device, and the first switching device and the first control device are connected, wherein the first control device is used for acquiring state parameters of a battery in the battery protection circuit, state information of the first switching device and the first control device, generating an internal control instruction based on the state parameters and the state information, and controlling the opening and closing state of the first switching device based on the internal control instruction.

6. The battery protection circuit of claim 5, wherein, The external control unit comprises a second switching device and a second control device, and the second switching device and the second control device are connected, wherein the second control device is used for acquiring state parameters of a battery in the battery protection circuit, generating an external control instruction based on the state parameters, and controlling the opening and closing state of the second switching device based on the external control instruction.

7. A control method of a battery protection circuit, applied to the battery protection circuit according to any one of claims 4 to 6, characterized in that, The control method comprises: acquiring first state information of the battery protection control unit and second state information of the external control unit; determining a current protection mode of the battery protection circuit and a corresponding protection control strategy based on the first state information and the second state information, and controlling the battery protection circuit to execute the protection control strategy.

8. The control method of the battery protection circuit according to claim 7, characterized by, The acquisition of the first state information of the battery protection control unit comprises: acquiring current state parameters of the battery, state information of the first switching device and the first control device; respectively determine whether the current state parameter is greater than a preset first parameter threshold and whether the state information is abnormal; when the current state parameter is not greater than the preset first parameter threshold or the state information is abnormal, generate an internal control instruction corresponding to controlling the first switching device to be in a closed state; when the current state parameter is greater than the preset first parameter threshold, generate an internal control instruction corresponding to controlling the first switching device to be in an open state; determine the internal control instruction as first state information of a battery protection control unit.

9. The control method of the battery protection circuit according to claim 8, wherein obtain second state information of an external control unit, including: obtain a current state parameter of a battery; determine whether the current state parameter is greater than a preset second parameter threshold, wherein the preset second parameter threshold is greater than the preset first parameter threshold; when the current state parameter is not greater than the preset second parameter threshold, generate an external control instruction corresponding to controlling a second switching device to be in an open state; when the current state parameter is greater than the preset second parameter threshold, generate an external control instruction corresponding to controlling the second switching device to be in a closed state; determine the external control instruction as second state information of the external control unit.

10. The control method of the battery protection circuit according to claim 9, wherein determine a current protection mode of a battery protection circuit and a corresponding protection control strategy based on the first state information and the second state information, including: respectively determine whether the first switching device in the internal control instruction is in a closed state and whether the second switching device in the external control instruction is in a closed state; when the first switching device is in a closed state and the second switching device is in an open state, determine that the current protection mode of the battery protection circuit is an internal protection mode only, and determine the internal control instruction as the protection control strategy; when the first switching device is in an open state and the second switching device is in a closed state, determine that the current protection mode of the battery protection circuit is an external protection mode only, and determine the external control instruction as the protection control strategy; when the first switching device is in a closed state and the second switching device is in a closed state, determine that the current protection mode of the battery protection circuit is an internal and external coexistence protection mode, and determine the internal control instruction and the external control instruction as the protection control strategy; when the first switching device is in an open state and the second switching device is in an open state, return to the step of obtaining the first state information of the battery protection control unit and the second state information of the external control unit.

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