Resettable fuse, battery protection circuit and control method thereof

Abstract

The invention relates to the technical field of electronics, and discloses a resettable fuse, a battery protection circuit and a control method thereof, and the method comprises the steps that the resettable fuse comprises two PPTC electrodes, and a polymer matrix material and conductive particles which are filled between the two PPTC electrodes, and the resettable 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, and the heating element is adjacent to or abutted against the polymer matrix material; and when the controllable electrode is in a conducting state, the heating element generates heat for heating the polymer matrix material. When the electrodes of the heating element are conducted, the heating element generates corresponding heat to disconnect the resettable fuse, active controllable protection of the resettable fuse PPTC is achieved, and the device has the remarkable advantages of being complete in control function and reliable in protection.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a resettable fuse, a battery protection circuit and a control method thereof. Background Art

[0002] The resettable fuse, abbreviated as PPTC (Polymer Positive Temperature Coefficient), is a passive protection device with automatic recovery function composed of polymer matrix material and conductive particles, including plug-in PPTC and SMD PPTC. The working principle of PPTC is: when an abnormal overcurrent passes through PPTC, the heat generated causes the polymer matrix material to expand, and the conductive particles wrapped outside the polymer matrix material will separate to cut off the conductive path of PPTC and increase the resistance of the resettable fuse, thereby reducing the abnormal overcurrent and protecting the circuit equipment from damage; when the abnormal overcurrent fault is cleared, the polymer matrix material of the resettable fuse shrinks to its original shape and reconnects the conductive particles, the conductive path of PPTC will be restored, and the resistance of the resettable fuse will return to its original low resistance state; this process can be repeated many times. Compared with traditional fuses that need to be replaced after overcurrent protection, PPTC can recover by itself after being triggered and disconnected, and can be reused. Therefore, it is widely used in consumer electronics, computer peripherals, power tools, electric vehicles, medical equipment and industrial equipment to protect circuits from electrical faults such as overload, short circuit and overvoltage.

[0003] Currently, the protection circuit containing small chip PPTC can only be disconnected passively when the current exceeds the rated specification, and cannot be actively controlled to disconnect when necessary. Therefore, the existing PPTC control function is relatively simple, and it is difficult to achieve active controllable protection of PPTC, and there are defects such as imperfect control function and unreliable protection. Summary of the invention

[0004] In view of this, the present invention provides a resettable fuse, a battery protection circuit and a control method thereof to solve the problems that the existing PPTC has a single control function, is difficult to realize active controllable protection of PPTC, and has imperfect control function and unreliable protection.

[0005] In a first aspect, the present invention provides a resettable fuse, the resettable fuse comprising two PPTC electrodes and a polymer matrix material and conductive particles filled between the two PPTC electrodes, the resettable 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 a power supply circuit of the heating element, wherein the heating element is adjacent to or abuts against the polymer matrix material;

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

[0008] The present invention adds a heating element and a heating element electrode in the resettable fuse, so that the heating element generates heat corresponding to the polymer matrix material when the controllable electrode is in a conducting state, so that the resettable fuse expands and disconnects, thereby achieving the purpose of controllable disconnection of the resettable fuse, making the function of the PPTC more perfect and the protection more reliable.

[0009] In an optional embodiment, one end of the heating element is connected to any PPTC electrode, and the other end is connected to the heating element electrode; the heating element electrode, one end of which is connected to the heating element, and the other end is connected to an external control unit and then connected to another PPTC electrode, is used to control its working state to be in an on state according to an external control instruction of the external control unit, control the heating element to generate corresponding heat, and disconnect the self-resetting fuse to achieve active controllable protection.

[0010] The present invention adds a heating element and a heating element electrode to the resettable fuse, so that the heating element can be connected to an external control unit, and the heating element is controlled to generate appropriate heat as required to expand the resettable fuse and thus disconnect, which not only realizes the active controllable protection of PPTC, but also makes the function of PPTC more perfect and the protection more reliable.

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

[0012] In a second aspect, the present invention provides a battery protection circuit, the battery protection circuit includes a battery and a positive and negative electrode thereof, a battery protection control unit and an output unit, one end of the battery protection control unit is connected to any one of the positive and negative electrodes of the battery, and the other end is connected to the output unit, the battery protection circuit also includes: a resettable fuse and an external control unit, the resettable fuse is a resettable fuse as described in the first aspect or any corresponding embodiment thereof;

[0013] Among them, any PPTC electrode of the resettable fuse is connected to the other electrode of the positive and negative electrodes of the battery, the other PPTC electrode is connected to the output unit, the heating element electrode is connected to one end of the external control unit, and the other end of the external control unit is connected to the battery protection control unit;

[0014] The external control unit generates an external control instruction for controlling the working state of the heating element electrode to be in the on state, controlling the heating element to generate corresponding heat, and disconnecting the resettable fuse to achieve active controllable protection. The battery protection circuit of the present invention can achieve passive and active controllable protection of the resettable fuse by designing the resettable fuse and the external control unit, so that the protection mode of the battery protection circuit is more diverse, the function is more complete, and the protection is more reliable.

[0015] In an optional embodiment, the battery protection control unit includes a first switching device and a first control device, which are connected to each other, wherein the first control device is used to obtain status parameters of a battery in a battery protection circuit, status information of the first switching device and the first control device, generate internal control instructions based on the status parameters and the status information, and control the opening and closing state of the first switching device based on the internal control instructions.

[0016] The present invention realizes basic circuit protection of the battery protection circuit by designing a battery protection control unit of a first switch device and a first control device.

[0017] In an optional embodiment, the external control unit includes a second switching device and a second control device, which are connected to each other, wherein the second control device is used to obtain state parameters of the battery in the battery protection circuit, generate external control instructions based on the state parameters, and control the opening and closing state of the second switching device based on the external control instructions.

[0018] The present invention realizes active controllable protection of the resettable fuse by designing the second switch device and the external control unit of the second control device, thereby realizing more diverse protection for the battery protection circuit, so as to ensure that the function of the battery protection circuit is more complete and the protection is more reliable.

[0019] In a third aspect, the present invention provides a control method for a battery protection circuit, which is applied to the battery protection circuit of the second aspect or any corresponding embodiment thereof, and the control method includes:

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

[0021] The current protection mode of the battery protection circuit and its 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.

[0022] The control method of the battery protection circuit of the present invention obtains first state information of the battery protection control unit and second state information of the external control unit for analysis, determines the current protection mode of the battery protection circuit and its 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, making the control function of the battery protection circuit more complete and the protection more reliable.

[0023] In an optional implementation, obtaining first status information of a battery protection control unit includes:

[0024] Acquire current state parameters of the battery, state information of the first switch device and the first control device;

[0025] Determine 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, an internal control instruction is generated to control the first switch device to be in a closed state;

[0027] When the current state parameter is greater than a preset first parameter threshold, an internal control instruction is generated to control the first switch device to be in an off state;

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

[0029] The present invention determines the first state information by determining the size of the current state parameter of the battery and its preset first parameter threshold value, combined with the abnormal determination of the state information of the first switching device and the first control device, which can ensure the quality of obtaining the first state information, help to improve the control accuracy of the battery protection circuit, and make its control function more complete and the protection more reliable.

[0030] In an optional implementation, obtaining second state information of the external control unit includes:

[0031] Get the current status parameters of the battery;

[0032] 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;

[0033] When the current state parameter is not greater than the preset second parameter threshold, an external control instruction is correspondingly generated to control the second switch device to be in an off state;

[0034] When the current state parameter is greater than a preset second parameter threshold, an external control instruction is correspondingly generated to control the second switch device to a closed state;

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

[0036] The present invention determines the second state information by judging the size of the current state parameter of the battery and its preset second parameter threshold value, which not only ensures the acquisition quality of the second state information, but also realizes the active controllable protection of PPTC, making the control function of the battery protection circuit more perfect and the protection more reliable.

[0037] In an optional implementation manner, determining a current protection mode of the battery protection circuit and its corresponding protection control strategy based on the first state information and the second state information includes:

[0038] respectively determining 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, determining that the current protection mode of the battery protection circuit is an internal protection mode only, and determining the internal control instruction as a protection control strategy;

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

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

[0042] When the first switch device is in the off state and the second switch device is in the off state, the process returns to the step of acquiring the first state information of the battery protection control unit and the second state information of the external control unit.

[0043] The present invention determines the current protection mode of the battery protection circuit and its corresponding protection control strategy 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 improve the control function of the battery protection circuit and further ensure the reliability of protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 is a structural schematic diagram of a resettable fuse according to an embodiment of the present invention;

[0046] Figure 2 is a schematic structural diagram of another resettable fuse according to an embodiment of the present invention;

[0047] Figure 3 This is a normal state diagram of a conventional resettable fuse;

[0048] Figure 4 This is a schematic diagram of the expansion disconnection state of a conventional resettable fuse;

[0049] Figure 5 is a cross-sectional view of a resettable fuse according to an embodiment of the present invention;

[0050] Figure 6 is a bottom view of a resettable fuse according to an embodiment of the present invention;

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

[0052] Figure 8 It is a schematic diagram of the structure of a conventional battery protection circuit;

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

[0054] Fig.10 is a flow chart of a control method of a battery protection circuit according to an embodiment of the present invention;

[0055] Fig.11 is a flow chart of another control method of a battery protection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0057] In this embodiment, a resettable fuse is provided. Figure 1 is a schematic diagram of the structure of a resettable fuse according to an embodiment of the present invention. Figure 1 As shown, the resettable fuse includes: two PPTC electrodes 101 and a polymer matrix material 102 and conductive particles 103 filled between the two PPTC electrodes. The resettable 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 against the polymer matrix material 102; when the controllable electrode of the heating element 104 is in a conducting state, the heating element 104 generates heat for heating the polymer matrix material.

[0058] It should be noted that the conventional resettable fuse is composed of two PPTC electrodes 101 forming a power supply circuit. In this embodiment, when the heating element 104 is added to the conventional resettable fuse, the power supply circuit of the heating element 104 is composed of two PPTC electrodes 101 and the heating element 104. Specifically, by adding the heating element 104 and the heating element electrode 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 on state, so that the resettable fuse expands and disconnects, which can achieve the purpose of controllable disconnection of the resettable fuse, making the function of PPTC more perfect 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 here, and are adaptively adjusted based on actual needs. For example, the electrodes at both ends of the resettable 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 metal conductive particles, which are only used as an exemplary description.

[0060] In this embodiment, the specific shape of the resettable fuse is adaptively adjusted based on the actual material and packaging process, such as a flat-head tubular fuse, a spiral fuse, a plug-in fuse, a chip fuse, etc., which are only used as exemplary illustrations.

[0061] In this embodiment, a resettable fuse is provided. Figure 2 is a schematic diagram of the structure of another resettable fuse according to an embodiment of the present invention. Figure 2 As shown, the heating element 104 of this embodiment is arranged at the bottom of the resettable fuse, one end of which is connected to any PPTC electrode 101, and the other end is connected to the heating element electrode 105. It should be noted that the bottom position of the resettable fuse is relative to the cross section or edge of the corresponding shape of the actual resettable fuse. For example, for a plug-in fuse, except for the pin part, if the shape of the fuse is a rectangle, the bottom position is the bottom edge of the rectangle; if it is a column, the bottom position is the bottom surface of the column. Specifically, the heating element 104 is arranged at the bottom of the resettable fuse, which is convenient for leading out the corresponding heating element electrode when making this type of resettable fuse, and ensures the universality of this type of resettable fuse.

[0062] In this embodiment, the heating element electrode 105 is a controllable electrode, one end of which is connected to the heating element 104, and the other end is connected to the external control unit and then connected to another PPTC electrode 101, and is used to control the heating element 104 to generate corresponding heat according to the external control instruction of the external control unit. The heat can cause the polymer matrix material to expand due to heat, thereby disconnecting the self-resetting fuse to achieve 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 resistor layer, and the heating element electrode is a heating resistor electrode.

[0064] In actual applications, the working principle of the conventional resettable fuse PPTC is as follows: when there is an over-specification current, that is, an abnormal overcurrent passing through the PPTC, the on-resistance of the PPTC itself will generate a large amount of heat to expand the polymer matrix material, and the conductive particles wrapped in the polymer matrix material will be stretched apart due to expansion, thereby cutting off the conductive path of the PPTC and causing the PPTC resistance to rise until it is disconnected, thereby blocking the passage of abnormal current. When the abnormal overcurrent disappears, the PPTC no longer generates heat, the polymer matrix material temperature decreases and shrinks to its original shape, reconnecting the conductive particles, restoring the conductive path, and restoring the PPTC resistance to its original low-resistance normal state. The above process can be repeated many times. Therefore, compared with the one-time use limitation of conventional fuses, the resettable fuse PPTC has the dual functions of overcurrent and overheat protection and automatic recovery.

[0065] In a specific embodiment, Figure 3 This is a normal state diagram of a conventional resettable fuse. Figure 4This is a schematic diagram of the expansion disconnection state of a conventional resettable fuse. Specifically, considering that the PPTC characteristic is that it presents a low resistance under normal current conditions, about a few milliohms to a few ohms; under overcurrent faults, the resistance rises sharply, thereby protecting the back-end circuit. Due to its excellent recoverability, when used for overcurrent protection, after the fault is eliminated, the circuit can automatically return to the on state. Its normal state can be referred to Figure 3 As shown; its expansion disconnection state can be referred to Figure 4 shown.

[0066] Based on the single control function of the existing PPTC, it is difficult to achieve active controllable protection of PPTC, and there are problems such as imperfect control function and unreliable protection. The resettable fuse in the embodiment of the present invention adds a resistor layer with a fixed resistance at the bottom of the PPTC device. The resistor layer can be connected to an external control circuit, and the resistor layer is controlled to generate appropriate heat as required to make the PPTC expand and disconnect, thereby achieving the purpose of controllable disconnection of PPTC; the PPTC with active heating resistor in this embodiment can not only maintain the passive disconnection characteristics of the original PPTC, but also complete the active disconnection of PPTC when it is necessary to control the heating of the resistor layer through an external circuit, so as to achieve passive and active controllable protection of PPTC, making the function of PPTC more perfect and the protection more reliable.

[0067] In a specific embodiment, Figure 5 This is a cross-sectional view of a resettable fuse according to an embodiment of the present invention; the PPTC of this embodiment adds a heating resistor layer at the bottom of the original PPTC, and the resistance value of the heating resistor layer can be customized according to the actual required heat generation. For example, the resistance value of the heating resistor layer can be customized according to the actual PPTC disconnection temperature required heat generation Q = I 2 R is set, and its value is generally set in the range of 0.5 to 1.5Ω. In addition, a controllable electrode, namely the heating resistor electrode, is led out from the bottom of the PPTC to the heating resistor layer. Among them, the other electrode of the heating resistor layer is shared with any of the two PPTC electrodes. Specifically, Figure 6 FIG. 1 is a bottom view of a resettable fuse according to an embodiment of the present invention. Figure 6 It can be seen that the left electrode of the heating resistor layer is fused with the left electrode of the PPTC, i.e., the PPTC electrode 601, to form a common electrode; the right electrode of the heating resistor layer is independently provided with an electrode, i.e., the heating resistor electrode 603; and it is connected to the right electrode of the PPTC, i.e., the PPTC electrode 602.

[0068] The resettable fuse of the embodiment of the present invention is a PPTC with an active heating resistor layer, that is, by adding a heating resistor layer and a heating resistor electrode at the bottom of a conventional PPTC, the heating resistor layer can be connected to an external control unit, and the heating resistor layer is controlled to generate appropriate heat as required to cause the PPTC to expand and disconnect, thereby realizing active controllable protection of the PPTC, making the function of the PPTC more complete and the protection more reliable.

[0069] In this embodiment, a battery protection circuit is provided. Figure 7 is a schematic diagram of the structure of a battery protection circuit according to an embodiment of the present invention. Figure 7 As 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. The battery protection circuit also includes: a resettable fuse 704 and an external control unit 705.

[0070] In this embodiment, one end of the resettable fuse 704 (i.e., any PPTC electrode) 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 (i.e., the other PPTC electrode is connected to the output unit 703, and the heating element electrode is connected to one end of the external control unit 705), and the other end of the external control unit 705 is connected to the battery protection control unit 702.

[0071] In this embodiment, the external control unit 705 generates an external control instruction for controlling the working state of the heating element electrode to be in the on state, controlling the heating element to generate corresponding heat, and disconnecting the self-resetting fuse 704 to achieve active controllable protection.

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

[0073] In this embodiment, the battery protection control unit 702 includes a first switch device 7021 and a first control device 7022, the first switch device 7021 and the first control device 7022 are connected, wherein the first control device 21 is used to obtain the state parameters of the battery 701 in the battery protection circuit, the state information of the first switch device 7021 and the first control device 7022, generate internal control instructions based on the state parameters and the state information, and control the opening and closing state of the first switch device 7021 based on the internal control instructions. Specifically, the battery protection control unit of the first switch 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 corresponding content of the state parameters of the battery 701 in this embodiment is not specifically limited here, and is adaptively adjusted based on actual needs. For example, the state parameters are the voltage, energy, power, etc. of the battery, which is only used as an exemplary description.

[0075] In this embodiment, the external control unit 705 includes a second switch device 7051 and a second control device 7052, and the second switch device 7051 and the second control device 7052 are connected, wherein the second control device 7052 is used to obtain the state parameters of the battery 701 in the battery protection circuit, generate an external control instruction based on the state parameters, and control the on and off state of the second switch device 7051 based on the external control instruction. Specifically, by designing the external control unit of the second switch device and the second control device to realize the active controllable protection of the resettable fuse, more diverse protection of the battery protection circuit is realized, so as to ensure that the function of the battery protection circuit is more perfect and the protection is more reliable.

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

[0077] In practical applications, conventional resettable fuses PPTC are widely used in battery protection circuits. The battery protection circuit based on conventional PPTC, that is, the structural diagram of the conventional battery protection circuit is as follows: Figure 7As shown. Specifically, the PPTC is directly connected in series to the positive or negative path of the lithium battery. If the output end of the circuit is abnormal, that is, there is an abnormal current that exceeds the rated specification of the PPTC; this abnormal current passes through the PPTC. Since the PPTC itself has a certain resistance, the large current exceeding the specification will cause the PPTC's own resistance to heat up and cause the PPTC to disconnect the output, thus playing a protective role. Figure 8 It can be seen that the control IC1 is an IC component of a conventional lithium battery protection circuit. Specifically, the control IC1 determines whether the lithium battery is in a safe operating range by monitoring the state parameters of the two ends of the lithium battery and the state parameters of the output unit (i.e., output -). If it is not in the safe operating range, the control switch device 1 is turned on to disconnect the output of the lithium battery and stop the lithium battery from working.

[0078] Based on the problem that the existing PPTC has a single control function and is difficult to realize active controllable protection of PPTC, the resettable fuse of the embodiment of the present invention is applied to the battery protection circuit, that is, the structural diagram of the battery protection circuit composed of the resettable fuse of the embodiment is as shown in FIG. Fig. 9 As shown. Specifically, the PPTC electrode 902 of this embodiment is connected to the positive electrode of the lithium battery (i.e., "+"); the PPTC electrode 901 is connected to one end of the output circuit (i.e., output +); the right electrode of the heating resistor layer in the PPTC (i.e., the heating resistor electrode 903) is connected to a switch device 2, and one end of the switch device 2 is connected to the negative electrode of the lithium battery (i.e., "-"); the control terminal of the switch device 2 is connected to the control IC2; it controls the on and off state of the switch device 2 based on actual applications, that is, when the switch device 2 is closed, the circuit is closed to form a loop, and the heating resistor layer generates heat due to the large current, and the heat is transferred to the PPTC, causing the PPTC to disconnect. By Fig. 9 It can be seen that when the control IC2 is not involved in the control, the PPTC has all the functions and protection effects of the current conventional PPTC. When the control IC2 is involved in the control, the control IC2 controls the opening and closing of the switch device 2, so that one end of the heating resistor layer in the PPTC is connected to the negative electrode of the lithium battery to form a path so that the resistor in the PPTC heating resistor layer heats up, generates heat, and then expands and disconnects the PPTC, thereby realizing the active control disconnection function of the PPTC.

[0079] It should be noted that the content of the determination of whether the control IC2 participates in the control is not limited here, and is adaptively set based on actual needs. Specifically, since the control IC2 is only responsible for controlling the switch device 2, that is, the control IC2 detects the state parameters of the lithium battery, such as when the voltage is higher than the set value V2, the control switch device 2 is closed, so that the heating resistor layer in the PPTC is connected to the circuit to generate heat. The control IC1 also has the function of controlling the switch device 1 to disconnect when it detects that the voltage of the lithium battery is higher than the set value V1, but in the setting, V2>V1, that is, during charging, the lithium battery voltage continues to rise, and when the voltage reaches V1, the control IC1 will disconnect the switch of the switch device 1, so that the charging circuit is disconnected. After the disconnection, the lithium battery voltage will no longer rise and cannot reach V2. In this case, the control IC2 will not act, that is, the control IC2 has no action. When the control IC1 or switch device 1 fails (i.e. fault state), the switch device 1 is still not disconnected after the battery voltage reaches V1, and the battery continues to be charged until the battery voltage rises to V2, when IC2 controls the switch device 2 to close and connect the heating resistor in the PPTC. The heating resistor generates heat due to the large current, and the heat causes the PPTC temperature to 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, since the current passing through the heating resistor passes through the PPTC, after the PPTC is disconnected, the heating resistor also has no current, that is, the heating resistor is no longer heating, and the PPTC will automatically resume conduction after the PPTC temperature drops.

[0080] In summary, the battery protection circuit of the embodiment of the present invention can realize passive and active controllable protection of the resettable fuse by designing the resettable fuse and the external control unit, so that the protection mode of the battery protection circuit is more diverse, the function is more complete, and the protection is more reliable.

[0081] In an embodiment of the present invention, 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 a 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 this embodiment, a control method for a battery protection circuit is provided. Fig.10 FIG. 1 is a flow chart of a control method of a battery protection circuit according to an embodiment of the present invention. Fig.10 As shown, the process includes the following steps:

[0083] Step S1001, obtaining first state information of a battery protection control unit and second state information of an external control unit.

[0084] It should be noted that the control method of the battery protection circuit of this embodiment is applied to the aforementioned battery protection circuit, see Figure 7 In this embodiment, the specific contents of the first state information and the second state information are not limited here, and are adaptively adjusted based on actual needs. For example, the first state information includes state parameters of the battery, such as voltage, operating state data of the first switch device and the first control device, etc., which is only used as an exemplary description.

[0085] Step S1002: determining a current protection mode of the battery protection circuit and its 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.

[0086] In this embodiment, the specific content of the current protection mode of the battery protection circuit and its 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 the internal protection mode of the conventional battery protection circuit and the external protection mode of the resettable fuse combined with this embodiment, which is only used as an exemplary description.

[0087] The control method of the battery protection circuit of the embodiment of the present invention obtains first state information of the battery protection control unit and second state information of the external control unit for analysis, determines the current protection mode of the battery protection circuit and its 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, making the control function of the battery protection circuit more complete and the protection more reliable.

[0088] In this embodiment, a control method for a battery protection circuit is provided. Fig.11 FIG. 1 is a flow chart of another control method of a battery protection circuit according to an embodiment of the present invention. Fig.11 As shown, the process includes the following steps:

[0089] Step S1101, obtaining first status information of the battery protection control unit and second status information of the external control unit.

[0090] In this embodiment, obtaining the first state information of the battery protection control unit includes:

[0091] Step A1, obtaining current state parameters of the battery, state information of the first switch device and the first control device.

[0092] It should be noted that the specific method for obtaining the current state parameters of the battery, the state information of the first switch device and the first control device in this embodiment is not limited here, and is determined based on conventional data acquisition methods in the art. For example, using a digital multimeter or other electronic testing instrument to read the current state parameters of the battery, such as voltage, is only an exemplary description.

[0093] Step A2, determining whether the current state parameter is greater than a 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 this embodiment are not limited here, and can be 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, an internal control instruction for controlling the first switch device to be in a closed state is generated accordingly.

[0096] In this embodiment, the detection method of whether the state information is abnormal is not limited here, and is adaptively adjusted based on actual needs. For example, the first control device is tested for appearance and function to determine whether it is abnormal; for the first switch device, such as a MOS switch, the MOS switch is placed under a microscope to observe whether it is broken and a multimeter is used to test the resistance of the MOS pin to see whether it is broken to determine whether it is abnormal, which is only an exemplary description.

[0097] Step A4: when the current state parameter is greater than a preset first parameter threshold, an internal control instruction is generated to control the first switch device to be in an off state.

[0098] Step A5: determining the internal control instruction as the first state information of the battery protection control unit.

[0099] In the embodiment of the present invention, the first state information is determined by judging the size of the current state parameter of the battery and its preset first parameter threshold value, combined with the abnormal judgment of the state information of the first switching device and the first control device, which can ensure the quality of obtaining the first state information, help improve the control accuracy of the battery protection circuit, and make its control function more complete and the protection more reliable.

[0100] In this embodiment, obtaining the second state information of the external control unit includes:

[0101] Step B1, obtaining the current state parameters of the battery.

[0102] In this embodiment, the method for obtaining the current battery status parameter is determined by referring to the content of step A1 above, and will not be described in detail here.

[0103] Step B2, determining 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 this embodiment, the specific content and value of the preset second parameter threshold are not limited here, and are adaptively adjusted based on actual needs.

[0105] Step B3: When the current state parameter is not greater than the preset second parameter threshold, an external control instruction is generated to control the second switch device to be in an off state.

[0106] Step B4: when the current state parameter is greater than the preset second parameter threshold, an external control instruction for controlling the second switch device to be in a closed state is generated accordingly.

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

[0108] The embodiment of the present invention determines the second state information by judging the size of the current state parameter of the battery and its preset second parameter threshold value, which not only ensures the quality of obtaining the second state information, but also realizes the active controllable protection of PPTC, making the control function of the battery protection circuit more perfect and the protection more reliable.

[0109] Step S1102: determining a current protection mode of the battery protection circuit and its 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, in the above step S1102, determining the current protection mode of the battery protection circuit and its corresponding protection control strategy based on the first state information and the second state information includes:

[0111] Step S11021, determining 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.

[0112] Step S11022: when the first switch device is in a closed state and the second switch 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 a protection control strategy.

[0113] Step S11023, when the first switch device is in an open state and the second switch 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 a protection control strategy.

[0114] Step S11024, when the first switch device is in a closed state and the second switch device is in a closed state, determining that the current protection mode of the battery protection circuit is an internal and external coexistence protection mode, and determining the internal control instruction and the external control instruction as a protection control strategy.

[0115] Step S11025, when the first switch device is in the off state and the second switch device is in the off state, return to the step of acquiring the first state information of the battery protection control unit and the second state information of the external control unit.

[0116] In the embodiment of the present invention, the current protection mode of the battery protection circuit and its 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 improve the control function of the battery protection circuit and further ensure the reliability of protection.

[0117] In summary, the control method of the battery protection circuit of the embodiment of the present invention is based on the battery protection circuit of PPTC with an active heating resistor, which can not only maintain the passive disconnection characteristics of the original PPTC and realize the basic protection function of the battery protection circuit, but also can control the heating of the heating resistor layer through an external circuit when necessary to make the PPTC actively disconnect, thereby realizing the passive and active controllable protection of the PPTC, making the function of the PPTC more complete and the protection more reliable.

[0118] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A resettable fuse, comprising two PPTC electrodes and a polymer matrix material and conductive particles filled between the two PPTC electrodes, characterized in that: The resettable 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 the power supply circuit of the heating element, wherein the heating element is adjacent to or abuts against the polymer matrix material; When the controllable electrode is in a conducting state, the heating element generates heat for heating the polymer matrix material.

2. The resettable fuse according to claim 1, characterized in that: One end of the heating element is connected to any one of the PPTC electrodes, and the other end is connected to the heating element electrode; the heating element electrode, one end of which is connected to the heating element, and the other end is connected to the external control unit and then connected to another PPTC electrode, is used to control the heating element to generate corresponding heat when its working state is in the on state according to the external control instruction of the external control unit, so that the self-resettable fuse is disconnected to achieve active controllable protection.

3. The resettable fuse according to claim 1, characterized in that: The heating element is a heating resistor layer, and the heating element electrode is a heating resistor electrode.

4. A battery protection circuit, comprising a battery and its positive and negative electrodes, a battery protection control unit and an output unit, wherein one end of the battery protection control unit is connected to any one of the positive and negative electrodes of the battery, and the other end is connected to the output unit, characterized in that: The battery protection circuit further comprises: a resettable fuse and an external control unit, wherein the resettable fuse is a resettable fuse as claimed in any one of claims 1 to 3; Wherein, any PPTC electrode of the resettable fuse is connected to the other electrode of the positive and negative electrodes of the battery, the other PPTC electrode is connected to the output unit, the heating element electrode is connected to one end of the external control unit, and the other end of the external control unit is connected to the battery protection control unit; The external control unit generates an external control instruction for controlling the working state of the heating element electrode to be in the on state, controlling the heating element to generate corresponding heat, and disconnecting the self-resetting fuse to achieve active controllable protection.

5. The battery protection circuit according to claim 4, characterized in that: The battery protection control unit includes a first switching device and a first control device, wherein the first switching device is connected to the first control device, wherein the first control device is used to obtain status parameters of a battery in a battery protection circuit, status information of the first switching device and the first control device, generate internal control instructions based on the status parameters and the status information, and control the opening and closing state of the first switching device based on the internal control instructions.

6. The battery protection circuit according to claim 5, characterized in that: The external control unit includes a second switching device and a second control device, and the second switching device is connected to the second control device, wherein the second control device is used to obtain the state parameters of the battery in the battery protection circuit, generate external control instructions based on the state parameters, and control the opening and closing state of the second switching device based on the external control instructions.

7. A control method for 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: Acquire first state information of the battery protection control unit and second state information of the external control unit; A current protection mode of the battery protection circuit and its corresponding protection control strategy are determined based on the first status information and the second status information, and the battery protection circuit is controlled to execute the protection control strategy.

8. The control method of the battery protection circuit according to claim 7, characterized in that: The obtaining of first status information of the battery protection control unit includes: Acquire current state parameters of the battery, state information of the first switch device and the first control device; 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, an internal control instruction is correspondingly generated to control the first switch device to be in a closed state; When the current state parameter is greater than the preset first parameter threshold, an internal control instruction is correspondingly generated to control the first switch device to be in an off state; The internal control instruction is determined as first state information of the battery protection control unit.

9. The control method of the battery protection circuit according to claim 8, characterized in that: Acquiring second state information of the external control unit, including: Get the current status parameters of the 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, an external control instruction for controlling the second switch device to be in an off state is correspondingly generated; When the current state parameter is greater than the preset second parameter threshold, an external control instruction for controlling the second switch device to be in a closed state is correspondingly generated; The external control command is determined as second state information of the external control unit.

10. The control method of the battery protection circuit according to claim 9, characterized in that: The determining, based on the first state information and the second state information, a current protection mode of the battery protection circuit and a corresponding protection control strategy thereof includes: respectively determining 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; When the first switch device is in a closed state and the second switch device is in an open state, determining that a current protection mode of the battery protection circuit is an internal protection mode only, and determining the internal control instruction as a protection control strategy; When the first switch device is in an open state and the second switch device is in a closed state, determining that a current protection mode of the battery protection circuit is an external protection mode only, and determining the external control instruction as a protection control strategy; When the first switch device is in a closed state and the second switch device is in a closed state, determining that a current protection mode of the battery protection circuit is an internal and external coexistence protection mode, and determining the internal control instruction and the external control instruction as a protection control strategy; When the first switch device is in the off state and the second switch device is in the off state, return to the step of acquiring the first state information of the battery protection control unit and the second state information of the external control unit.

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