Protection circuit and method thereof

Abstract

The present application relates to a protection circuit and a method thereof. The protection circuit is applied to a lithium battery provided with a charge and discharge circuit, and the protection circuit includes a first pre-discharge circuit and a regulating circuit, wherein the regulating circuit and the discharge control switch of the charge and discharge circuit are connected in parallel, the regulating circuit includes a second switch element and a capacitor component connected in series, the first pre-discharge circuit and the discharge control switch are connected in parallel or in parallel with the capacitor component, and the first pre-discharge circuit includes a first switch element and a first resistor component connected in series. The controller of the charge and discharge circuit controls the conduction or disconnection of the first switch element and / or the second switch element to charge the capacitor component or discharge energy through the first resistor component. Therefore, the problem of damage to the discharge control switch due to excessive short-circuit current can be avoided, and the protection circuit has the technical effect of low cost, easy manufacture and operation.

Description

Technical Field

[0001] The present application relates to the field of protection circuits, and in particular to a protection circuit and a method thereof. Background Art

[0002] With the advancement of technology, the application of lithium batteries is becoming increasingly widespread. When a lithium battery short-circuits, the internal battery pack generates a back electromotive force. As the internal resistance of high-power battery packs decreases, the short-circuit current increases, potentially damaging the battery pack and potentially causing danger. Therefore, for stability and safety considerations, lithium batteries must be equipped with protection mechanisms to avoid these hazards.

[0003] With the increasing use of lithium batteries in high-power products, the short-circuit current generated by high-power lithium batteries when they short-circuit can reach as high as 1,000 to 5,000 amperes. Therefore, the existing technology uses high-power switching elements as discharge control switches. At the moment of a high-power lithium battery short-circuit, the discharge control switch is disconnected to prevent damage to the high-power lithium battery pack. However, due to the high short-circuit current of high-power lithium batteries, the high-power switching elements are still prone to damage and failure due to the excessive short-circuit current. In addition, the existing technology also suffers from the high cost caused by the difficulty in obtaining high-power switching elements.

[0004] In light of this, relevant industry experts have proposed a protection circuit that connects multiple switching elements in parallel to a discharge control switch. When a high-power lithium battery short-circuits, in addition to disconnecting the discharge control switch, the current can also be diverted by the switching elements connected in parallel with the discharge control switch, thereby resolving the issue of the discharge control switch being easily damaged by large short-circuit currents. However, the more switching elements connected in parallel with the discharge control switch, the higher the cost and size of the protection circuit, and the greater the difficulty in controlling the consistency of the switching elements.

[0005] In summary, it can be seen that the existing technology has long had problems such as high manufacturing cost and larger volume of the protection circuit due to the use of multiple switching elements connected in parallel to the discharge control switch, and difficulty in consistent control of the switching elements. Therefore, it is necessary to propose improved technical means to solve this problem. Summary of the Invention

[0006] The embodiments of the present application provide a protection circuit and method thereof, which solve the long-standing problems in the prior art of using multiple switching elements to connect the discharge control switch in parallel, resulting in high production costs and larger volume of the protection circuit, and difficulty in consistent control of the switching elements.

[0007] In order to solve the above technical problems, this application is implemented as follows:

[0008] In one embodiment, a protection circuit is provided for a lithium battery provided with a charge-discharge circuit, the charge-discharge circuit including a discharge control switch, a charge control switch, and a controller. The protection circuit includes: a first pre-discharge circuit and a regulation circuit. The regulation circuit is connected in parallel with the discharge control switch and includes a second switch element and a capacitor component connected in series; the first pre-discharge circuit is connected in parallel with the discharge control switch or in parallel with the capacitor component and includes a first switch element and a first resistor component connected in series. The controller is used to control the conduction or disconnection of the first switch element and / or the second switch element to charge the capacitor component or discharge energy through the first resistor component.

[0009] In another embodiment, a protection method is provided for a lithium battery equipped with a protection circuit and a charge-discharge circuit, wherein the charge-discharge circuit includes a discharge control switch, a charge control switch, and a controller; the protection circuit includes a first pre-discharge circuit and a regulation circuit, the regulation circuit being connected in parallel with the discharge control switch, the regulation circuit including a second switch element and a capacitor assembly connected in series; the first pre-discharge circuit being connected in parallel with the discharge control switch or the capacitor assembly, the first pre-discharge circuit including a first switch element and a first resistor assembly connected in series. The protection method includes the following steps: when a short circuit occurs after the lithium battery is discharged, the controller disconnects the discharge control switch and connects the second switch element, allowing the capacitor assembly to absorb the energy of the back electromotive force generated by the lithium battery via the regulation circuit.

[0010] In one embodiment, when the lithium battery is about to perform a normal discharge operation, the protection method further includes the following steps: before the lithium battery is discharged, the controller turns on the first switching element to allow the lithium battery to pre-discharge through the first resistor component; before the lithium battery is discharged and after the first switching element is turned on, the controller turns on the second switching element to discharge the energy of the capacitor component through the first resistor component; and before the lithium battery is discharged and within a predetermined time after the first switching element is turned on, the controller turns off the first switching element and turns on the discharge control switch to allow the lithium battery to discharge to a load.

[0011] In an embodiment of the present application, the on or off state of the first switching element and / or the second switching element can be controlled by a controller, thereby avoiding the problem of damage to the discharge control switch due to excessive short-circuit current, and the protection circuit has the technical effect of low cost, easy production and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0013] Figure 1 is a schematic diagram of a lithium battery provided with a protection circuit according to the first embodiment of the present application;

[0014] Figure 2A is a schematic diagram of a lithium battery provided with a protection circuit according to a second embodiment of the present application;

[0015] Figure 2B is a schematic diagram of a lithium battery provided with a protection circuit according to a third embodiment of the present application;

[0016] Figure 2C is a schematic diagram of a lithium battery provided with a protection circuit according to a fourth embodiment of the present application;

[0017] Figure 2D is a schematic diagram of a lithium battery provided with a protection circuit according to a fifth embodiment of the present application;

[0018] Figure 3A is a schematic diagram of a lithium battery provided with a protection circuit according to a sixth embodiment of the present application;

[0019] Figure 3B is a schematic diagram of a lithium battery provided with a protection circuit according to a seventh embodiment of the present application;

[0020] Figure 3C is a schematic diagram of a lithium battery provided with a protection circuit according to an eighth embodiment of the present application;

[0021] Figure 4 is a schematic diagram of a lithium battery provided with a protection circuit according to a ninth embodiment of the present application;

[0022] Figure 5 This is a flow chart of a protection method according to an embodiment of the present application;

[0023] Figure 6 yes Figure 1 A flowchart of a protection method for a lithium battery when it is about to undergo normal discharge operation; and

[0024] Figure 7 yes Figure 4 Flowchart of the protection method for a lithium battery during normal discharge operation. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] See also Figure 1 , Figure 1 Schematic diagram of a lithium battery provided with a protection circuit according to the first embodiment of the present application. Figure 1As shown, the protection circuit 100 is applied to a lithium battery provided with a charge and discharge circuit 70, and is configured in a battery load loop formed by a battery cell 50 of the lithium battery and a load 60. The two ends of the battery cell 50 of the lithium battery are a positive terminal B+ and a negative terminal B-, respectively. The charge and discharge circuit 70 includes a discharge control switch 72, a charge control switch 74, and a controller 76. The protection circuit 100 includes: a first pre-discharge circuit 110 and a regulation circuit 120. The charge control switch 74 and the discharge control switch 72 are connected in series, and the regulation circuit 120, the first pre-discharge circuit 110, and the discharge control switch 72 are connected in parallel. The first pre-discharge circuit 110 includes a first switch element 112 and a first resistor component 114 connected in series, and the regulation circuit 120 includes a second switch element 122 and a capacitor component 124 connected in series. The discharge control switch 72 is used to control the discharge path of the lithium battery cell 50; the charge control switch 74 is used to control the charge path of the lithium battery cell 50; and the controller 76 is used to control the conduction or disconnection of the first switch element 112, the second switch element 122, the discharge control switch 72, and the charge control switch 74. The controller 76 controls the conduction or disconnection of the first switch element 112 or the second switch element 122 to charge the capacitor element 124 or discharge energy through the first resistor element 114.

[0027] In one embodiment, the first switch element 112 and the second switch element 122 may be Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) switches, wherein the MOSFET switch may be a switch element that is easily available and has common power. In another embodiment, the first switch element 112 and the second switch element 122 may be Insulated Gate Bipolar Transistor (IGBT).

[0028] In one embodiment, the discharge control switch 72 and the charge control switch 74 can both be N-type MOSFET switches, and the discharge control switch 72 and the charge control switch 74 are placed in series "face to face" (e.g., Figure 1 As shown, the drain of the discharge control switch 72 is connected to the drain of the charge control switch 74); in another embodiment, the discharge control switch 72 and the charge control switch 74 can both be P-type MOSFET switches, and the discharge control switch 72 and the charge control switch 74 are placed in series "back to back" (i.e., the drain of the discharge control switch 72 is connected to the drain of the charge control switch 74).

[0029] See also Figure 2A , Figure 2A Schematic diagram of a lithium battery provided with a protection circuit according to the second embodiment of the present application. Figure 2A In the embodiment, the first resistor component 114 includes a resistor R1, and the capacitor component 124 includes a capacitor C1. Before the lithium battery is discharged, the controller 76 turns on the first switch element 112 to pre-discharge the lithium battery cell 50 through the resistor R1. Then, within a predetermined time after turning on the first switch element 112, the controller 76 turns off the first switch element 112 and turns on the discharge control switch 72 to discharge the lithium battery cell 50 into the load 60. More specifically, if the protection circuit 100 for a lithium battery does not include the first pre-discharge circuit 110, the lithium battery cell 50 will output a large current at the moment it supplies power to the load 60 due to the low impedance of the load 60, including the capacitors, which could easily trigger a short circuit in the lithium battery. To address this issue, the first pre-discharge circuit 110 allows the controller 76 to first turn on the first switch element 112 before the lithium battery cell 50 supplies power to the load 60 (i.e., before turning on the discharge control switch 72). This allows the lithium battery cell 50 to provide a pre-discharge current to the load 60 via the first pre-discharge circuit 110, allowing the voltage of the capacitors in the load 60 to rise to a certain level before discharging. Therefore, the controller 76 can turn on the discharge control switch 72 and then turn off the first switch element 112 within a predetermined time after turning on the first switch element 112, allowing the lithium battery cell 50 to discharge the load 60. This ensures that the lithium battery cell 50 will not short circuit when it supplies power to the load 60. The preset time can be adjusted according to actual needs. The specific method of adjusting the preset time is well known to those with ordinary knowledge in the field to which the invention belongs, so it will not be described in detail here.

[0030] When the controller 76 turns on the first switch element 112 , the resistor R1 can be used as a current limiting resistor to achieve current limiting output of the lithium battery. The larger the resistance value, the smaller the current value of the pre-discharge current.

[0031] In one embodiment, before the lithium battery is discharged, the controller 76 turns on the first switch element 112 to pre-discharge the lithium battery cell 50 through the resistor R1. After turning on the first switch element 112, the controller 76 turns on the second switch element 122 to discharge the energy of the capacitor C1 through the resistor R1. Within a predetermined time after turning on the first switch element 112, the controller 76 turns off the first switch element 112 and turns on the discharge control switch 72 to discharge the lithium battery cell 50 to the load 60. Because the capacitor C1 inevitably selects the shortest discharge path to discharge its stored energy, when the second switch element 122 is turned on, the capacitor C1 discharges its stored energy through the resistor R1.

[0032] In one embodiment, when the lithium battery cell 50 is supplying power to the load 60 (i.e., the lithium battery is discharging), the controller 76 may turn on the discharge control switch 72 and selectively turn off the first switch element 112. If a short circuit occurs in the lithium battery after discharge (e.g., a short circuit occurs in the load 60), the controller 76 may turn off the discharge control switch 72 and turn on the second switch element 122, allowing the capacitor C1 to absorb the back electromotive force energy generated by the lithium battery. In more detail, after the lithium battery cell 50 discharges the load 60, if a short circuit occurs, the current output by the lithium battery cell 50 will suddenly increase. To prevent the discharge control switch 72 from being damaged by the large short-circuit current, the controller 76 can disconnect the discharge control switch 72; then, the controller 76 can turn on the second switch element 122 to reduce the change in current through the capacitor C1 (the capacitor C1 can absorb energy; if the capacitor C1 has previously discharged through the resistor R1, it can absorb more energy at this time); and because the back electromotive force voltage is proportional to the change in current, the back electromotive force voltage generated by the lithium battery also decreases accordingly, thereby protecting the discharge control switch 72 from damage due to the short circuit event. In one embodiment, if a short circuit occurs after the lithium battery is discharged, the controller 76 can selectively disconnect or connect the first switch element 112. When the first switch element 112 is in the on state, the resistor R1 connected in series with the first switch element 112 can ensure that the short-circuit current does not burn the first switch element 112. When the first switch element 112 is in the off state, the first switch element 112 is not damaged by the short-circuit current.

[0033] In one embodiment, the controller 76 may further disconnect the discharge control switch 72 when the lithium battery is powered off, thereby disconnecting the second switch element 122. By disconnecting the second switch element 122 when the lithium battery is powered off, the capacitor C1 may be prevented from aging due to being in a constant charging or discharging state.

[0034] In one embodiment, the protection circuit 100 may further include a short-circuit monitoring circuit 130 connected to two opposite ends of the series-connected charge control switch 74 and discharge control switch 72 (i.e., end point X and end point Y) and a controller 76. The short-circuit monitoring circuit 130 is configured to continuously monitor whether the voltage difference between the two opposite ends of the series-connected charge control switch 74 and discharge control switch 72 (i.e., the voltage difference between end point X and end point Y) is greater than a threshold value; if so, a short-circuit signal is output to the controller 76, causing the controller 76 to control the discharge control switch 72 to be in an off state and the second switch element 122 to be in an on state. The threshold value may be adjusted based on actual needs. In other words, when the short-circuit monitoring circuit 130 determines whether a short-circuit event has occurred by monitoring whether the voltage difference between end point X and end point Y is greater than the threshold value, a short-circuit signal is output to the controller 76, which then activates the protection mechanism (i.e., the controller 76 controls the discharge control switch 72 to be in an off state and controls the second switch element 122 to be in an on state) to prevent damage to the lithium battery.

[0035] See also Figures 2B to 2D , Figure 2B is a schematic diagram of a lithium battery provided with a protection circuit according to the third embodiment of the present application. Figure 2C is a schematic diagram of a lithium battery provided with a protection circuit according to a fourth embodiment of the present application. Figure 2D Schematic diagram of a lithium battery provided with a protection circuit according to the fifth embodiment of the present application. Figures 2B to 2D It can be seen that the capacitor component 124 may not only include a capacitor, but also have different structures. Figure 2B In one embodiment shown, the capacitor component 124 may include a capacitor C2 and a resistor R2 connected in series; Figure 2C In one embodiment shown, the capacitor component 124 may include a capacitor C3 and a resistor R3 connected in parallel; Figure 2D In one embodiment shown, the capacitor component 124 may include a capacitor C4, a capacitor C5, and a resistor R4, wherein the capacitor C5 and the resistor R4 are connected in series, and the capacitor C4 and the series capacitor C5 and the resistor R4 are connected in parallel. It should be understood that Figures 2B to 2D The operating principle of the capacitor element 124 of the embodiment and Figure 2A The operating principle of the capacitor component 124 of the embodiment is the same; when a short circuit event occurs after the lithium battery is discharged, the controller 76 can disconnect the discharge control switch 72 and turn on the second switch element 122 to make the capacitor included in the capacitor component 124 (for example: Figure 2A Capacitor C1, Figure 2B Capacitor C2, Figure 2C Capacitor C3, Figure 2D Capacitors C4 and C5 absorb the energy of the back electromotive force generated by the lithium battery, reduce the change in current, and thus achieve a protective effect, which will not be described in detail here.

[0036] See also Figures 3A to 3C , Figure 3A is a schematic diagram of a lithium battery provided with a protection circuit according to a sixth embodiment of the present application; Figure 3B is a schematic diagram of a lithium battery provided with a protection circuit according to a seventh embodiment of the present application; Figure 3C Schematic diagram of a lithium battery provided with a protection circuit according to the eighth embodiment of the present application. Figures 3A to 3C It can be seen that compared with Figure 1 , the first pre-discharge circuit 110 can be changed to be connected in parallel with the capacitor component 124, and the first resistor component 114 can have a different structure; Figure 3B In the embodiment shown, the first resistor component 114 may include a resistor R5; Figure 3C In one embodiment shown, the first resistor component 114 may include a capacitor C6 and a resistor R6 connected in series. It should be understood that Figures 3A to 3C The operating principle of the first resistance element 114 of the embodiment and Figure 2A The operating principle of the first resistor element 114 of the embodiment is the same; before the lithium battery is discharged, the controller 76 turns on the first switch element 112 to allow the battery cell 50 of the lithium battery to pass through the resistor included in the first resistor element 114 (for example: Figure 2A The resistor R1, Figure 3B The resistor R5, Figure 3C After the controller 76 turns on the first switch element 112, the controller 76 turns on the second switch element 122 to pass the resistor included in the first resistor component 114 (for example: Figure 2A The resistor R1, Figure 3B The resistor R5, Figure 3C The resistor R6) discharges the energy of the capacitor component 124, which will not be described in detail here.

[0037] Also, see Figure 4 , Figure 4 Schematic diagram of a lithium battery provided with a protection circuit according to the ninth embodiment of the present application. Figure 4 In the embodiment, the first pre-discharge circuit 110 and the capacitor component 124 are connected in parallel, and the protection circuit 100 may further include a second pre-discharge circuit 140. The second pre-discharge circuit 140 and the discharge control switch 72 are connected in parallel and include a third switch element 142 and a second resistor component 144 connected in series. The controller 76 may also be used to control the conduction or disconnection of the third switch element 142. The second resistor component 144 may include a resistor (such as Figure 3B The first resistive component 114) or a resistor and a capacitor in series (such as Figure 3CWhen the controller 76 controls the third switch element 142 to be turned on, the controller 76 controls the first switch element 112 to be turned off; or when the controller 76 controls the third switch element 142 to be turned off, the controller 76 controls the first switch element 112 to be turned on (i.e., the actuation of the third switch element 142 is opposite to the actuation of the first switch element 112). In one embodiment, before the lithium battery is discharged, the controller 76 turns on the first switch element 112 and turns off the third switch element 142 to pre-discharge the lithium battery through the first resistor component 114; before the lithium battery is discharged, after the first switch element 112 is turned on and the third switch element 142 is turned off, the controller 76 turns on the second switch element 122 to discharge the energy of the capacitor component 124 through the first resistor component 114; and before the lithium battery is discharged, within a default time after the first switch element 112 is turned on and the third switch element 142 is turned off, the controller 76 turns off the first switch element 112 and turns on the discharge control switch 72 and the third switch element 142 to discharge the lithium battery to the load 60.

[0038] See also Figure 5 , Figure 5 This is a flow chart of a protection method according to an embodiment of the present application. Figure 5 As shown, the protection method is applied to a lithium battery including a charge and discharge circuit 70 and a protection circuit 100, wherein the charge and discharge circuit 70 includes a discharge control switch 72, a charge control switch 74 and a controller 76, and the protection circuit 100 includes: a first pre-discharge circuit 110 and a regulating circuit 120, the charge control switch 74 and the discharge control switch 72 are connected in series, the regulating circuit 120 and the discharge control switch 72 are connected in parallel, the regulating circuit 120 includes a second switch element 122 and a capacitor component 124 connected in series, the first pre-discharge circuit 110 and the discharge control switch 72 are connected in parallel or in parallel with the capacitor component 124 and include a first switch element 112 and a resistor R1 connected in series. The protection method includes the steps of: when a short circuit event occurs after the lithium battery is discharged, the controller 76 disconnects the discharge control switch 72 and turns on the second switch element 122, allowing the capacitor component 124 to absorb the energy of the back electromotive force generated by the lithium battery through the regulating circuit 120 (step 210).

[0039] See also Figure 1 and Figure 6 , Figure 6 yes Figure 1 Flow chart of the protection method for lithium batteries when they are about to undergo normal discharge operation. Figure 1 and Figure 6 As shown, in Figure 1When the lithium battery is about to perform a normal discharge operation, the protection method further includes the following steps: before the lithium battery is discharged, the controller 76 turns on the first switch element 112 to allow the lithium battery to pre-discharge through the first resistor element 114 (step 310); before the lithium battery is discharged and after the first switch element 112 is turned on, the controller 76 turns on the second switch element 122 to discharge the energy of the capacitor element 124 through the first resistor element 114 (step 320); and before the lithium battery is discharged and within a predetermined time after the first switch element 112 is turned on, the controller 76 turns off the first switch element 112 and turns on the discharge control switch 72 to allow the lithium battery to discharge to the load 60 (step 330).

[0040] See also Figure 4 and Figure 7 , Figure 7 yes Figure 4 Flow chart of the protection method for lithium batteries when they are about to undergo normal discharge operation. Figure 4 and Figure 7 As shown, in Figure 4 When the lithium battery is about to perform a normal discharge operation, the protection method further includes the following steps: before the lithium battery is discharged, the controller 76 turns on the first switch element 112 and turns off the third switch element 142 to allow the lithium battery to pre-discharge through the first resistor element 114 (step 410); before the lithium battery is discharged and after the first switch element 112 is turned on and the third switch element 142 is turned off, the controller 76 turns on the second switch element 122 to discharge the energy of the capacitor element 124 through the first resistor element 114 (step 420); and before the lithium battery is discharged and within a predetermined time after the first switch element 112 is turned on and the third switch element 142 is turned off, the controller 76 turns off the first switch element 112 and turns on the discharge control switch 72 and the third switch element 142 to allow the lithium battery to discharge to the load 60 (step 430).

[0041] In one embodiment, the protection method may further include the following steps: when the lithium battery is powered off, the controller 76 disconnects the discharge control switch 72 and the first switch element 112 .

[0042] In one embodiment, the protection circuit 100 may further include a short-circuit monitoring circuit 130, which is connected to two opposite ends of the charge control switch 74 and the discharge control switch 72 connected in series (i.e., end point X and end point Y) and the controller 76, so that the protection method may further include the steps of: the short-circuit monitoring circuit 130 continuously monitoring whether the voltage difference between the two opposite ends of the charge control switch 74 and the discharge control switch 72 connected in series is greater than a threshold; and if so, the short-circuit monitoring circuit 130 outputs a short-circuit signal to the controller 76, so that the controller 76 controls the discharge control switch 72 to be in an off state and controls the second switch element 122 to be in an on state.

[0043] In summary, the present application provides a protection circuit and method thereof, which avoids the problem of damage to the discharge control switch due to excessive short-circuit current by controlling the on or off state of the first switching element and / or the second switching element, and the protection circuit has the technical effect of low cost, easy production and operation. In addition, before the lithium battery is discharged, the first switching element is turned on by the controller or the on or off state of the first switching element and the third switching element is controlled, so that the lithium battery provides a pre-discharge current to the load, ensuring that the lithium battery does not trigger a short-circuit event at the moment of supplying power to the load. In addition, before the lithium battery is discharged, the second switching element is turned on by the controller, so that the capacitor component discharges its stored energy through the first resistor component, ensuring that when a short-circuit event occurs in the future and the second switching element is turned on, the capacitor component can absorb more energy. In addition, when a short-circuit event occurs after the lithium battery is discharged, by disconnecting the discharge control switch and turning on the second switching element, the capacitor component absorbs the energy of the back electromotive force, protecting the discharge control switch from being damaged by the short-circuit event. Furthermore, if a short circuit occurs after the lithium battery is discharged, the first switch element is in the on state, and the first resistor component connected in series with the first switch element can ensure that the short circuit current does not burn the first switch element.

[0044] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0045] The terms "first," "second," and "third" used in this document are used to modify components in the claims and are not used to indicate a priority order, a precedence relationship, or that one component precedes another, or a temporal order in performing method steps. They are only used to distinguish components with the same name.

[0046] It should be understood that when a component is described as being "connected" or "coupled" to another component, it can be directly connected or coupled to the other component, and intervening components may be present. Conversely, when a component is described as being "directly connected" or "directly coupled" to another component, no intervening components are present. In addition, unless otherwise specified in the specification, any term in the singular includes the plural.

[0047] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A protection circuit applied to a lithium battery provided with a charge and discharge circuit, wherein the charge and discharge circuit includes a discharge control switch, a charge control switch and a controller, characterized in that: The protection circuit comprises: a regulating circuit connected in parallel with the discharge control switch and comprising a second switching element and a capacitor component connected in series; and A first pre-discharge circuit is connected in parallel with the discharge control switch or the capacitor component, comprising a first switch element and a first resistor component connected in series; The controller is configured to control the first switch element or the second switch element to be turned on or off, so as to charge the capacitor component or discharge energy through the first resistor component; Wherein, when a short circuit event occurs, the controller turns off the discharge control switch and turns on the second switch element, and the capacitor component absorbs the energy of the back electromotive force generated by the short circuit event; Wherein, before the lithium battery is discharged and after the first switch element is turned on, the controller is used to turn on the second switch element to discharge the energy of the capacitor component through the first resistor component.

2. The protection circuit according to claim 1, wherein: Before the lithium battery is discharged, the controller is used to turn on the first switch element to allow the lithium battery to be pre-discharged through the first resistor component.

3. The protection circuit according to claim 1, wherein: Before the lithium battery is discharged and within a preset time after the first switch element is turned on, the controller turns off the first switch element and turns on the discharge control switch to enable the lithium battery to discharge to a load.

4. The protection circuit according to claim 1, wherein: When the lithium battery is powered off, the controller is used to disconnect the discharge control switch and the first switching element.

5. The protection circuit according to claim 1, wherein: The protection circuit further includes a short circuit monitoring circuit connected to two opposite ends of the charging control switch and the discharging control switch connected in series.

6. The protection circuit according to claim 1, wherein: When the first pre-discharge circuit and the capacitor component are connected in parallel, the protection circuit also includes a second pre-discharge circuit, the second pre-discharge circuit and the discharge control switch are connected in parallel and include a third switching element and a second resistor component connected in series, and the controller is also used to control the conduction or disconnection of the third switching element.

7. The protection circuit according to claim 6, wherein: When the controller controls the third switching element to be turned on, the controller controls the first switching element to be turned off; or when the controller controls the third switching element to be turned off, the controller controls the first switching element to be turned on.

8. A protection method, applied to a lithium battery provided with a protection circuit and a charge-discharge circuit, wherein: The charge-discharge circuit includes a discharge control switch, a charge control switch, and a controller; the protection circuit includes a first pre-discharge circuit and a regulation circuit; the charge control switch and the discharge control switch are connected in series; the regulation circuit and the discharge control switch are connected in parallel; the regulation circuit includes a second switch element and a capacitor component connected in series; the first pre-discharge circuit and the discharge control switch are connected in parallel or in parallel with the capacitor component; the first pre-discharge circuit includes a first switch element and a first resistor component connected in series; and the protection method includes the steps of: The controller controls the first switch element or the second switch element to be turned on or off so as to charge the capacitor component or discharge energy through the first resistor component; When a short circuit event occurs, the controller turns off the discharge control switch and turns on the second switch element, allowing the capacitor component to absorb the energy of the back electromotive force generated by the short circuit event through the regulation circuit; and When the lithium battery is to perform a normal discharge operation, before the lithium battery is discharged and after the first switch element is turned on, the controller turns on the second switch element to discharge the energy of the capacitor element through the first resistor element.

9. The protection method according to claim 8, characterized in that: When the lithium battery is about to perform the normal discharge operation, the protection method further includes the steps of: Before the lithium battery is discharged, the controller turns on the first switch element to allow the lithium battery to be pre-discharged through the first resistor component; as well as Before the lithium battery is discharged and within a preset time after the first switch element is turned on, the controller turns off the first switch element and turns on the discharge control switch to enable the lithium battery to discharge to a load.

10. The protection method according to claim 8, characterized in that: The protection circuit further includes a short-circuit monitoring circuit connected to opposite ends of the charge control switch and the discharge control switch connected in series and the controller. The protection method further includes the steps of: The short circuit monitoring circuit continuously monitors whether the voltage difference between the two opposite ends of the charge control switch and the discharge control switch connected in series is greater than a threshold; and If so, the short-circuit monitoring circuit outputs a short-circuit signal to the controller, so that the controller controls the discharge control switch to be in an off state and controls the second switch element to be in an on state.

11. The protection method according to claim 8, wherein: When the first pre-discharge circuit and the capacitor component are connected in parallel, the protection circuit further includes a second pre-discharge circuit, which is connected in parallel with the discharge control switch and includes a third switch element and a second resistor component connected in series. When the lithium battery is about to perform the normal discharge operation, the protection method further includes the steps of: Before the lithium battery is discharged, the controller turns on the first switch element and turns off the third switch element, so that the lithium battery is pre-discharged through the first resistor component; Before the lithium battery is discharged and after the first switch element is turned on and the third switch element is turned off, the controller turns on the second switch element to discharge the energy of the capacitor component through the first resistor component; as well as Before the lithium battery is discharged and within a default time after the first switch element is turned on and the third switch element is turned off, the controller turns off the first switch element and turns on the discharge control switch and the third switch element to enable the lithium battery to discharge to a load.

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