CN114448000A - Protection circuit and method thereof - Google Patents
Protection circuit and method thereof Download PDFInfo
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- CN114448000A CN114448000A CN202011216144.2A CN202011216144A CN114448000A CN 114448000 A CN114448000 A CN 114448000A CN 202011216144 A CN202011216144 A CN 202011216144A CN 114448000 A CN114448000 A CN 114448000A
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- Prior art keywords
- circuit
- discharge
- lithium battery
- control switch
- switching element
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00304—Overcurrent protection
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
- H01M10/4257—Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
- H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2200/00—Safety devices for primary or secondary batteries
- H01M2200/30—Preventing polarity reversal
Abstract
The application relates to a protection circuit and a method thereof. The protection circuit is applied to the lithium cell that is provided with charge and discharge circuit, and the protection circuit includes first pre-discharge circuit and regulating circuit, and wherein, regulating circuit and charge and discharge circuit's the control switch that discharges connect in parallel, and regulating circuit includes second switch element and the electric capacity subassembly of establishing ties, and first pre-discharge circuit connects in parallel or connects in parallel with the electric capacity subassembly with the control switch that discharges, and first pre-discharge circuit includes first switch element and the first resistance subassembly of establishing ties. The controller of the charging and discharging circuit controls the first switch element and/or the second switch element to be switched on or switched off so as to charge the capacitor assembly or discharge energy through the first resistor assembly. Therefore, the problem that the discharge control switch is damaged due to overlarge short-circuit current can be avoided, and the protection circuit has the technical effects of low cost and easiness in manufacturing and operating.
Description
Technical Field
The present disclosure relates to the field of protection circuits, and more particularly, to a protection circuit and a method thereof.
Background
With the development of science and technology, the application of lithium batteries is increasingly widespread. When the lithium battery is short-circuited, the battery pack in the lithium battery generates back electromotive force, and under the condition that the internal resistance of the high-power battery pack is smaller and smaller, the short-circuit current is larger and larger, so that the battery pack is damaged and danger occurs, therefore, on the basis of stability and safety considerations, a protection mechanism is required to be added to the lithium battery to avoid the danger.
With the increasing application of lithium batteries in high-power products, and the short-circuit current generated when the high-power lithium battery is short-circuited can reach 1000 to 5000 amperes, therefore, in the prior art, a high-power switching element is used as a discharge control switch, and at the moment when the high-power lithium battery is short-circuited, the battery pack of the high-power lithium battery is prevented from being damaged by disconnecting the discharge control switch; however, since the short-circuit current of the high-power lithium battery is large, there is a problem that the high-power switching element is still easily damaged and fails due to the excessive short-circuit current. In addition, the prior art also has the problem of high cost caused by the difficulty in obtaining high-power switching elements.
In view of the above, the related art proposes a protection circuit in which a plurality of switching devices are connected in parallel to a discharge control switch, so that at the instant of short circuit of a high power lithium battery, the discharge control switch is turned off, and current can be shunted by the switching devices connected in parallel to the discharge control switch, thereby solving the problem that the discharge control switch is easily damaged due to a large short-circuit current. However, the larger the number of switching elements connected in parallel with the discharge control switch, the higher the cost and the larger the size of the protection circuit, and the greater the difficulty in controlling the consistency of the switching elements.
In summary, it is known that in the prior art, there have been problems that the manufacturing cost of the protection circuit is high, the size is large and the consistency control of the switching elements is difficult due to the fact that a plurality of switching elements are connected in parallel to the discharge control switch, and therefore, an improved technical means is needed to solve the problems.
Disclosure of Invention
The embodiment of the application provides a protection circuit and a method thereof, and solves the problems that in the prior art, the manufacturing cost of the protection circuit is high, the size is larger and the consistency control of switching elements is difficult because a plurality of switching elements are connected in parallel with a discharge control switch for a long time.
In order to solve the technical problem, the present application is implemented as follows:
in one embodiment, a protection circuit is provided and applied to a lithium battery provided with a charging and discharging circuit, wherein the charging and discharging circuit comprises a discharging control switch, a charging control switch and a controller. The protection circuit includes: a first pre-discharge circuit and a regulation circuit. The regulating circuit is connected with the discharge control switch in parallel and comprises a second switching element and a capacitor component which are connected in series; the first pre-discharge circuit is connected in parallel with the discharge control switch or the capacitor component, and comprises a first switch element and a first resistor component which are connected in series. The controller is used for controlling the first switching element and/or the second switching element to be switched on or switched off so as to charge the capacitor assembly or discharge energy through the first resistor assembly.
In another embodiment, a protection method is provided, which is applied to a lithium battery provided with a protection circuit and a charge and discharge circuit, wherein the charge and discharge circuit comprises a discharge control switch, a charge control switch and a controller, the protection circuit comprises a first pre-discharge circuit and an adjusting circuit, the adjusting circuit and the discharge control switch are connected in parallel, and the adjusting circuit comprises a second switch element and a capacitor assembly which are connected in series; the first pre-discharge circuit is connected with the discharge control switch in parallel or connected with the capacitor assembly in parallel, and comprises a first switch element and a first resistor assembly which are connected in series. The protection method comprises the following steps: when the lithium battery generates a short-circuit event after discharging, the controller disconnects the discharge control switch and switches on the second switch element, and the capacitor assembly absorbs the energy of the counter electromotive force generated by the lithium battery through the regulating circuit.
In one embodiment, when the lithium battery is going to perform a normal discharge operation, the protection method further includes the steps of: before the lithium battery discharges, the controller conducts the first switch element so that the lithium battery is pre-discharged through the first resistance assembly; before the lithium battery discharges and after the first switch element is conducted, the controller conducts the second switch element so as to discharge the energy of the capacitor assembly through the first resistance assembly; and before the lithium battery discharges and within a default time after the first switch element is switched on, the controller switches off the first switch element and switches on the discharge control switch so as to enable the lithium battery to discharge to the load.
In the embodiment of the present application, the controller can control the on or off state of the first switch element and/or the second switch element, so as to avoid the problem of the discharge control switch being damaged due to the excessive short-circuit current, and the protection circuit has the technical effects of low cost and easy manufacturing and operation.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic diagram of a lithium battery provided with a protection circuit according to a first embodiment of the present application;
fig. 2A is a schematic diagram of a lithium battery provided with a protection circuit according to a second embodiment of the present application;
fig. 2B is a schematic diagram of a lithium battery provided with a protection circuit according to a third embodiment of the present application;
fig. 2C is a schematic view of a lithium battery provided with a protection circuit according to a fourth embodiment of the present application;
fig. 2D is a schematic diagram of a lithium battery provided with a protection circuit according to a fifth embodiment of the present application;
fig. 3A is a schematic view of a lithium battery provided with a protection circuit according to a sixth embodiment of the present application;
fig. 3B is a schematic view of a lithium battery provided with a protection circuit according to a seventh embodiment of the present application;
fig. 3C is a schematic view of a lithium battery provided with a protection circuit according to an eighth embodiment of the present application;
fig. 4 is a schematic view of a lithium battery provided with a protection circuit according to a ninth embodiment of the present application;
FIG. 5 is a flow chart of a method of guarding according to an embodiment of the present application;
FIG. 6 is a flow chart of a protection method for the lithium battery of FIG. 1 to perform a normal discharge operation; and
fig. 7 is a flowchart illustrating a protection method of the lithium battery of fig. 4 when the lithium battery is to perform a normal discharge operation.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 is a schematic diagram of a lithium battery provided with a protection circuit according to a first embodiment of the present application. As shown in fig. 1, the protection circuit 100 is applied to a lithium battery provided with a charge and discharge circuit 70, and is configured on a battery load loop formed by a battery cell 50 and a load 60 of the lithium battery, wherein two ends of the battery cell 50 of the lithium battery are a positive terminal B + and a negative terminal B ", respectively, and 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 charging control switch 74 and the discharging control switch 72 are connected in series, the adjusting circuit 120, the first pre-discharging circuit 110 and the discharging control switch 72 are connected in parallel, the first pre-discharging circuit 110 includes a first switching element 112 and a first resistor component 114 which are connected in series, and the adjusting circuit 120 includes a second switching element 122 and a capacitor component 124 which are connected in series. The discharge control switch 72 is used to control a discharge path for discharging the battery cell 50 of the lithium battery; the charge control switch 74 is used to control a charging path for charging the battery cell 50 of the lithium battery; the controller 76 is used to control the turning on or off of the first switching element 112, the second switching element 122, the discharging control switch 72, and the charging control switch 74. The controller 76 controls the first switch element 112 or the second switch element 122 to be turned on or off, so as to charge the capacitor element 124 or discharge energy through the first resistor element 114.
In one embodiment, the first switch element 112 and the second switch element 122 can be Metal-Oxide-Semiconductor Field-Effect-Transistor (MOSFET) switches, wherein the MOSFET switches can be readily available switching elements with common power; in another embodiment, the first switching element 112 and the second switching element 122 may be Insulated Gate Bipolar Transistors (IGBTs).
In one embodiment, the discharge control switch 72 and the charge control switch 74 may be N-type MOSFET switches, and the discharge control switch 72 and the charge control switch 74 are placed in a "face-to-face" series connection (as shown in fig. 1, 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 may 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).
Referring to fig. 2A, fig. 2A is a schematic diagram of a lithium battery with a protection circuit according to a second embodiment of the present application. In FIG. 2A, first resistive element 114 includes a resistor R1 and capacitive element 124 includes a capacitor C1. Before the lithium battery is discharged, the controller 76 turns on the first switching element 112 to pre-discharge the battery cell 50 of the lithium battery through the resistor R1; next, within a default time after the first switching element 112 is turned on, the controller 76 turns off the first switching element 112 and turns on the discharge control switch 72, so that the battery cell 50 of the lithium battery discharges to the load 60. More specifically, if the protection circuit 100 applied to the lithium battery does not include the first pre-discharge circuit 110, when the battery cell 50 of the lithium battery supplies power to the load 60, a large current is output due to the fact that the load 60 includes a capacitor and has no impedance value, and a short circuit of the lithium battery is easily triggered, in order to solve the above problem, by providing the first pre-discharge circuit 110, the controller 76 may lead the first switch element 112 before the battery cell 50 of the lithium battery supplies power to the load 60 (i.e., before the discharge control switch 72 is turned on), so that the battery cell 50 of the lithium battery can supply a pre-discharge current to the load 60 through the first pre-discharge circuit 110 and discharge after the voltage of the capacitor included in the load 60 rises to a certain level in advance, and therefore, the controller 76 may turn on the discharge control switch 72 and turn off the first switch element 112 within a default time after the first switch element 112 is turned on, so that the battery cell 50 of the lithium battery discharges to the load 60. Thus, it is ensured that the short circuit of the lithium battery is not triggered at the moment when the load 60 is supplied with power from the battery cell 50 of the lithium battery. The preset time can be adjusted according to actual requirements, and it is well known to those skilled in the art that how to adjust the preset time is not described in detail herein.
When the controller 76 turns on the first switching element 112, the resistor R1 may be used as a current limiting resistor for realizing a current limiting output of the lithium battery, and the larger the resistance value of the current limiting resistor, the smaller the current value of the pre-discharge current.
In one embodiment, before the lithium battery is discharged, the controller 76 turns on the first switching element 112 to pre-discharge the battery cell 50 of the lithium battery through the resistor R1; after turning on the first switching element 112, the controller 76 turns on the second switching element 122 to discharge the energy of the capacitor C1 through the resistor R1; within a default time after turning on the first switching element 112, the controller 76 turns off the first switching element 112 and turns on the discharge control switch 72 to discharge the battery cell 50 of the lithium battery to the load 60. Since the capacitor C1 necessarily selects the shortest discharge path to discharge its stored energy, the capacitor C1 discharges its stored energy through the resistor R1 when the second switching element 122 is turned on.
In one embodiment, when the battery cell 50 of the lithium battery supplies power to the load 60 (i.e., the lithium battery discharges), the controller 76 may turn on the discharge control switch 72 and selectively turn off the first switching element 112. When a short circuit event occurs after the lithium battery is discharged (e.g., the load 60 is short circuited), the controller 76 may turn off the discharge control switch 72 and turn on the second switching element 122, so that the capacitor C1 absorbs the energy of the back electromotive force generated by the lithium battery. In more detail, after the battery cell 50 of the lithium battery discharges the load 60, if a short-circuit event occurs, the current output by the battery cell 50 of the lithium battery may suddenly increase, and in order to prevent the discharge control switch 72 from being damaged due to a large short-circuit current, the controller 76 may turn off the discharge control switch 72; then, the controller 76 may turn on the second switch element 122 to reduce the current variation through the capacitor C1 (the capacitor C1 may absorb energy; if the capacitor C1 previously discharged through the resistor R1, more energy may be absorbed); since the back electromotive voltage and the current variation are in direct proportion, the back electromotive voltage generated by the lithium battery is also reduced, thereby protecting the discharge control switch 72 from being damaged by a short-circuit event. In one embodiment, if a short-circuit event occurs after the lithium battery is discharged, the controller 76 may selectively turn off or on the first switch element 112; when the first switching element 112 is in the conducting state, the resistor R1 connected in series with the first switching element 112 can ensure that the short-circuit current does not burn the first switching 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.
In one embodiment, the controller 76 may also turn off the discharge control switch 72 and thus the second switching element 122 when the lithium battery is powered down. By turning off the second switch element 122 when the lithium battery is powered down, the aging problem of the capacitor C1 caused by the fact that the capacitor C1 is always in a charging or discharging state can be avoided.
In one embodiment, the protection circuit 100 may further include a short circuit monitoring circuit 130 connecting the two opposite terminals (i.e., terminal X and terminal Y) of the series connection of the charge control switch 74 and the discharge control switch 72 and the controller 76. The short-circuit monitoring circuit 130 is configured to continuously monitor whether a voltage difference between opposite terminals of the series-connected charge control switch 74 and the discharge control switch 72 (i.e., a voltage difference between the terminal X and the terminal Y) is greater than a threshold value; if so, a short-circuit signal is output 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 switching element 122 to be in an on state. Wherein, the threshold value can be adjusted according to the actual requirement. In other words, when the short-circuit monitoring circuit 130 determines whether a short-circuit event occurs through whether the voltage difference between the monitoring terminal X and the monitoring terminal Y is greater than the threshold, if so, the short-circuit signal is output to the controller 76, and the controller 76 starts the protection mechanism (i.e., the controller 76 controls the discharge control switch 72 to be in the off state and the second switch element 122 to be in the on state), so as to prevent damage to the lithium battery.
Referring to fig. 2B to 2D, fig. 2B is a schematic diagram of a lithium battery with a protection circuit according to a third embodiment of the present application, fig. 2C is a schematic diagram of a lithium battery with a protection circuit according to a fourth embodiment of the present application, and fig. 2D is a schematic diagram of a lithium battery with a protection circuit according to a fifth embodiment of the present application. As can be seen from fig. 2B to 2D, the capacitor assembly 124 may have different structures besides one capacitor. In one embodiment, shown in FIG. 2B, the capacitive element 124 may include a capacitor C2 and a resistor R2 connected in series; in one embodiment shown in FIG. 2C, the capacitive element 124 may include a capacitor C3 and a resistor R3 connected in parallel; in one embodiment shown in fig. 2D, the capacitor assembly 124 may include a capacitor C4, a capacitor C5, and a resistor R4, wherein the capacitor C5 is connected in series with the resistor R4, and the capacitor C4 is connected in parallel with the capacitor C5 and the resistor R4. It should be understood that the principle of operation of the capacitive component 124 of the embodiment of fig. 2B-2D is the same as the principle of operation of the capacitive component 124 of the embodiment of fig. 2A; when a short-circuit event occurs after the lithium battery is discharged, the controller 76 may turn off the discharge control switch 72 and turn on the second switch element 122, so that the capacitors (e.g., the capacitor C1 of fig. 2A, the capacitor C2 of fig. 2B, the capacitor C3 of fig. 2C, and the capacitor C4 and the capacitor C5 of fig. 2D) included in the capacitor assembly 124 absorb energy of the back electromotive force generated by the lithium battery, and reduce the amount of current variation, thereby achieving the protection effect, which is not described herein again.
Referring to fig. 3A to 3C, fig. 3A is a schematic diagram of a lithium battery with a protection circuit according to a sixth embodiment of the present application; fig. 3B is a schematic view of a lithium battery provided with a protection circuit according to a seventh embodiment of the present application; fig. 3C is a schematic diagram of a lithium battery provided with a protection circuit according to an eighth embodiment of the present application. As shown in fig. 3A to 3C, compared to fig. 1, the first pre-discharge circuit 110 may be changed to be connected in parallel with the capacitor element 124, and the first resistor element 114 may have a different structure; in one embodiment, shown in FIG. 3B, the first resistive element 114 may include a resistor R5; in one embodiment, shown in FIG. 3C, the first resistive element 114 may include a capacitor C6 and a resistor R6 connected in series. It should be understood that the principle of operation of the first resistive element 114 of the embodiment of fig. 3A to 3C is the same as the principle of operation of the first resistive element 114 of the embodiment of fig. 2A; before the lithium battery is discharged, the controller 76 turns on the first switching element 112 to pre-discharge the battery cell 50 of the lithium battery through the resistor (e.g., the resistor R1 of fig. 2A, the resistor R5 of fig. 3B, and the resistor R6 of fig. 3C) included in the first resistor assembly 114; after the controller 76 turns on the first switch element 112, the controller 76 turns on the second switch element 122 to discharge the energy of the capacitor element 124 through the resistor (e.g., the resistor R1 in fig. 2A, the resistor R5 in fig. 3B, and the resistor R6 in fig. 3C) included in the first resistor element 114, which is not described herein again.
In addition, referring to fig. 4, fig. 4 is a schematic diagram of a lithium battery provided with a protection circuit according to a ninth embodiment of the present application. In fig. 4, the first pre-discharge circuit 110 is connected in parallel with the capacitor assembly 124, the protection circuit 100 may further include a second pre-discharge circuit 140, the second pre-discharge circuit 140 is connected in parallel with the discharge control switch 72 and includes a third switching element 142 and a second resistor assembly 144 connected in series, and the controller 76 may be further configured to control the third switching element 142 to be turned on or off. The second resistor element 144 may include a resistor (e.g., the first resistor element 114 of fig. 3B) or a resistor and a capacitor (e.g., the first resistor element 114 of fig. 3C) connected in series. Wherein, when the controller 76 controls to turn on the third switching element 142, the controller 76 controls to turn off the first switching element 112; or when the controller 76 controls to turn off the third switch element 142, the controller 76 controls to turn on the first switch element 112 (i.e., the actuation of the third switch element 142 and the actuation of the first switch element 112 are reversed). In one embodiment, before the lithium battery is discharged, the controller 76 turns on the first switching element 112 and turns off the third switching element 142, so that the lithium battery is pre-discharged through the first resistor assembly 114; before the lithium battery discharges and after the first switching element 112 is turned on and the third switching element 142 is turned off, the controller 76 turns on the second switching element 122 to discharge the energy of the capacitor assembly 124 through the first resistor assembly 114; and before the lithium battery is discharged and within a default time after the first switching element 112 is turned on and the third switching element 142 is turned off, the controller 76 turns off the first switching element 112 and turns on the discharge control switch 72 and the third switching element 142 to discharge the lithium battery to the load 60.
Referring to fig. 5, fig. 5 is a flowchart illustrating a protection method according to an embodiment of the present application. As shown in fig. 5, the protection method is applied to a lithium battery including a charging and discharging circuit 70 and a protection circuit 100, wherein the charging and discharging circuit 70 includes a discharging control switch 72, a charging control switch 74 and a controller 76, and the protection circuit 100 includes: the first pre-discharge circuit 110 and the adjusting circuit 120, the charge control switch 74 and the discharge control switch 72 are connected in series, the adjusting circuit 120 and the discharge control switch 72 are connected in parallel, the adjusting circuit 120 comprises a second switching element 122 and a capacitor assembly 124 which are connected in series, the first pre-discharge circuit 110 and the discharge control switch 72 are connected in parallel or connected in parallel with the capacitor assembly 124 and comprise a first switching element 112 and a resistor R1 which are connected in series. The protection method comprises the following steps: when a short circuit event occurs after the lithium battery is discharged, the controller 76 turns off the discharge control switch 72 and turns on the second switching element 122, so that the capacitor assembly 124 absorbs the energy of the back electromotive force generated by the lithium battery via the regulating circuit 120 (step 210).
Referring to fig. 1 and 6, fig. 6 is a flowchart illustrating a protection method of the lithium battery of fig. 1 when the lithium battery is to perform a normal discharge operation. As shown in fig. 1 and fig. 6, when the lithium battery of fig. 1 is going to perform a normal discharge operation, the protection method further includes the steps of: before the lithium battery is discharged, the controller 76 turns on the first switching element 112 to pre-discharge the lithium battery through the first resistance component 114 (step 310); before the lithium battery discharges and after the first switching element 112 is turned on, the controller 76 turns on the second switching element 122 to discharge the energy of the capacitor assembly 124 through the first resistor assembly 114 (step 320); and before the lithium battery is discharged and within a default time after the first switching element 112 is turned on, the controller 76 turns off the first switching element 112 and turns on the discharge control switch 72 to discharge the lithium battery to the load 60 (step 330).
Referring to fig. 4 and 7, fig. 7 is a flowchart illustrating a protection method of the lithium battery of fig. 4 when the lithium battery is to perform a normal discharge operation. As shown in fig. 4 and 7, when the lithium battery of fig. 4 is going to perform a normal discharge operation, the protection method further includes the steps of: before the lithium battery is discharged, the controller 76 turns on the first switching element 112 and turns off the third switching element 142, so that the lithium battery is pre-discharged through the first resistance component 114 (step 410); before discharging the lithium battery, after turning on the first switching element 112 and turning off the third switching element 142, the controller 76 turns on the second switching element 122 to discharge the energy of the capacitor assembly 124 through the first resistor assembly 114 (step 420); and within a default time before the lithium battery is discharged and after the first switching element 112 is turned on and the third switching element 142 is turned off, the controller 76 turns off the first switching element 112 and turns on the discharge control switch 72 and the third switching element 142 to discharge the lithium battery to the load 60 (step 430).
In an embodiment, the protection method may further include the steps of: when the lithium battery is powered down, the controller 76 turns off the discharge control switch 72 and the first switching element 112.
In one embodiment, the guarding circuit 100 may further include a short circuit monitoring circuit 130 connecting the two opposite terminals (i.e., the terminal X and the terminal Y) of the charge control switch 74 and the discharge control switch 72 connected in series and the controller 76, such that the guarding method may further include the steps of: the short circuit monitoring circuit 130 continuously monitors whether the voltage difference between the opposite ends of the series of charge control switch 74 and discharge control switch 72 is greater than a threshold value; 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 the off state and controls the second switching element 122 to be in the on state.
In summary, the present application provides a protection circuit and a method thereof, which avoid the problem of damage of a discharge control switch due to an excessive short-circuit current by controlling the on or off state of a first switch element and/or a second switch element, and the protection circuit has the technical effects of low cost and easy manufacture and operation. In addition, before the lithium battery discharges, the first switch element is conducted through the controller or the conducting or disconnecting state of the first switch element and the third switch element is controlled, so that the lithium battery provides pre-discharge current for the load, and the short-circuit event cannot be triggered at the moment when the lithium battery supplies power to the load. In addition, before the lithium battery discharges, the second switch element is conducted through the controller, so that the capacitor assembly discharges the energy stored in the capacitor assembly through the first resistor assembly, and the capacitor assembly can absorb more energy when a short-circuit event occurs in the future and the second switch element is conducted. In addition, when a short-circuit event occurs after the lithium battery is discharged, the capacitor assembly absorbs the energy of the back electromotive force by turning off the discharge control switch and turning on the second switching element, so that the discharge control switch is protected from being damaged by the short-circuit event. Furthermore, if the lithium battery is in a short-circuit event after discharging, the first switch element is in a conducting state, and the first resistor component connected in series with the first switch element can ensure that the first switch element is not burnt by short-circuit current.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The use of words such as "first," "second," "third," etc. herein is used to modify a claimed element and is not intended to imply a priority order, precedence relationship, or order between elements or steps of a method or process.
It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is described as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. In addition, any reference to singular is intended to include the plural unless the specification specifically states otherwise.
While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (13)
1. The utility model provides a protection circuit, is applied to the lithium cell that is provided with charge-discharge circuit, charge-discharge circuit includes discharge control switch, charge control switch and controller, its characterized in that, protection circuit includes:
the regulating circuit is connected with the discharge control switch in parallel and comprises a second switching element and a capacitor assembly which are connected in series; and
the first pre-discharge circuit is connected with the discharge control switch in parallel or connected with the capacitor assembly in parallel and comprises a first switch element and a first resistor assembly which are connected in series;
the controller is configured to control turning on or off the first switching element or the second switching element to charge the capacitor assembly or discharge energy through the first resistor assembly.
2. The protection circuit of claim 1, wherein the controller is configured to turn on the first switching element to pre-discharge the lithium battery through the first resistive component before the lithium battery is discharged.
3. The protection circuit of claim 2, wherein the controller is configured to turn on the second switching element to discharge the energy of the capacitive component through the first resistive component before the lithium battery is discharged and after the first switching element is turned on.
4. The protection circuit of claim 2, wherein the controller turns off the first switching element and turns on the discharge control switch to discharge the lithium battery to the load before the lithium battery is discharged and within a default time after the first switching element is turned on.
5. The protection circuit of claim 1, wherein the controller is configured to open the discharge control switch and turn on the second switching element to enable the capacitor assembly to absorb energy of back electromotive force generated by the lithium battery in the event of a short circuit after the lithium battery is discharged.
6. The protection circuit of claim 1, wherein the controller is configured to open the discharge control switch and the first switching element when the lithium battery is powered down.
7. The protection circuit of claim 1, further comprising a short circuit monitoring circuit connecting opposite ends of the charge control switch and the discharge control switch in series.
8. The protection circuit of claim 1, wherein when the first pre-discharge circuit is in parallel with the capacitive component, the protection circuit further comprises a second pre-discharge circuit in parallel with the discharge control switch and comprising a third switching element and a second resistive component in series, the controller further being configured to control turning on or off the third switching element.
9. The protection circuit of claim 8, wherein when the controller controls turning on the third switching element, the controller controls turning off the first switching element; or when the controller controls to turn off the third switching element, the controller controls to turn on the first switching element.
10. A protection method is applied to a lithium battery provided with a protection circuit and a charge-discharge circuit, wherein the charge-discharge circuit comprises a discharge control switch, a charge control switch and a controller, the protection circuit comprises a first pre-discharge circuit and an adjusting circuit, the charge control switch and the discharge control switch are connected in series, the adjusting circuit is connected in parallel with the discharge control switch, the adjusting circuit comprises a second switch element and a capacitor component which are connected in series, the first pre-discharge circuit is connected in parallel with the discharge control switch or connected in parallel with the capacitor component, the first pre-discharge circuit comprises a first switch element and a first resistor component which are connected in series, and the protection method is characterized by comprising the following steps:
when a short-circuit event occurs after the lithium battery discharges, the controller disconnects the discharge control switch, switches on the second switch element, and allows the capacitor assembly to absorb the energy of the back electromotive force generated by the lithium battery through the regulating circuit.
11. The method of claim 10, wherein the method further comprises, when the lithium battery is to perform a normal discharge operation, the steps of:
before the lithium battery discharges, the controller turns on the first switching element so that the lithium battery is pre-discharged through the first resistance component;
before the lithium battery discharges and after the first switch element is switched on, the controller switches on the second switch element so as to discharge the energy of the capacitor assembly through the first resistor assembly; and
before the lithium battery discharges and within a default time after the first switch element is turned on, the controller turns off the first switch element and turns on the discharge control switch, so that the lithium battery discharges to a load.
12. The protection method according to claim 10, wherein the protection circuit further includes a short-circuit monitoring circuit connecting opposite terminals of the charge control switch and the discharge control switch connected in series and the controller, the protection method further comprising the steps of:
the short circuit monitoring circuit continuously monitors whether the voltage difference between the two opposite end points of the charging control switch and the discharging control switch which are connected in series is larger than a threshold value; 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 a disconnected state and controls the second switch element to be in a connected state.
13. The protection method of claim 10, wherein when the first pre-discharge circuit and the capacitive component are connected in parallel, the protection circuit further comprises a second pre-discharge circuit connected in parallel with the discharge control switch and comprising a third switching element and a second resistive component connected in series; when the lithium battery is to perform normal discharge operation, the protection method further comprises the following steps:
before the lithium battery discharges, the controller turns on the first switching element and turns off the third switching element, so that the lithium battery is pre-discharged through the first resistance component;
before the lithium battery discharges and after the first switching element is turned on and the third switching element is turned off, the controller turns on the second switching element to discharge the energy of the capacitor assembly through the first resistance assembly; and
before the lithium battery discharges and within a default time after the first switching element is turned on and the third switching element is turned off, the controller turns off the first switching element and turns on the discharge control switch and the third switching element, so that the lithium battery discharges to a load.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011216144.2A CN114448000A (en) | 2020-11-04 | 2020-11-04 | Protection circuit and method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011216144.2A CN114448000A (en) | 2020-11-04 | 2020-11-04 | Protection circuit and method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114448000A true CN114448000A (en) | 2022-05-06 |
Family
ID=81361292
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011216144.2A Pending CN114448000A (en) | 2020-11-04 | 2020-11-04 | Protection circuit and method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114448000A (en) |
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2020
- 2020-11-04 CN CN202011216144.2A patent/CN114448000A/en active Pending
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