Battery protection system

Abstract

The invention provides a battery protection system. The battery protection circuit comprises a battery, a charging power switch, a discharging power switch, a load / charging positive electrode end, a load negative electrode end P-connected with a negative electrode of the battery through the discharging power switch, a charging negative electrode end CH-connected with the negative electrode of the battery through the charging power switch, and a battery protection circuit connected between the positive electrode and the negative electrode of the battery. The battery protection circuit comprises a charging control end, a discharging control end and a charger detection end connected with the charging negative electrode end CH-, whether the charging negative electrode end CH-is connected with a charger or not is detected according to the voltage of the charger detection end, and when it is detected that the charger is connected, the charging negative electrode end CH-is connected with the charger. And the discharge power switch is controlled to be switched off through the discharge control end. Therefore, after the charger is connected, the battery stops discharging to the load, and the charger does not supply power to the load, so that the battery is effectively charged while the overload risk of the charger is eliminated.

Description

[Technical field]

[0001] The present invention relates to the field of circuit design, and in particular to a battery protection system. [Background technology]

[0002] The battery protection system needs to realize the discharge and charge functions with protection at the same time. Figure 1 FIG. 1 is a circuit diagram of a battery protection system in the prior art. Figure 1 As shown, P+ / CH+ is the load / charging positive terminal, which can be connected to the positive pole of the load power supply or the positive pole of the charger output; CH- is the charging negative terminal, which can be connected to the negative pole of the charger output; P- is the load negative terminal, which is not drawn in the figure, and can be connected to the node MID_NODE or CH-. The battery can be a single cell or a plurality of cascaded cells.

[0003] The battery protection circuit is used to detect the charger or load status through the detection terminal VM, and RVM is a current limiting protection resistor. The battery protection circuit can be a battery protection chip. The battery protection circuit controls the NMOS charging power switch MNC through the charging control terminal CO, and controls the NMOS discharge power switch MND through the discharge control terminal DO. VCC is the power pin of the battery protection circuit, and VSS is the ground pin of the battery protection circuit. If the battery includes multiple cells connected in series, the battery protection circuit will have more pins for detecting the voltage of each cell. RS is a current detection resistor. If there is no current detection resistor RS, the on-resistance of the discharge power switch MND or the sum of the on-resistances of the charging power switches MND and MNC is equivalent to the current detection resistor.

[0004] Under the existing technology, if a charger is connected between the positive charging terminal CH+ and the negative charging terminal CH-, and at the same time, a load is connected between the positive load terminal P+ and the negative load terminal P-, the charger will supply power to the load directly or through the charging power switch MNC; if the current required by the load exceeds the limit of the charger at this time, the battery will not be effectively charged, and there will be a risk of charger overload.

[0005] Therefore, it is necessary to propose an improved technical solution to overcome the above problems. [Summary of the invention]

[0006] The present invention provides a battery protection system which can solve one of the above problems.

[0007] According to one aspect of the present invention, the present invention provides a battery protection system, comprising: a battery, a charging power switch, a discharging power switch; a load / charging positive terminal connected to the positive electrode of the battery; a load negative terminal P-, connected to the negative electrode of the battery through the discharging power switch; a charging negative terminal CH- independent of the load negative terminal P-, connected to the negative electrode of the battery through the charging power switch; a battery protection circuit connected between the positive and negative electrodes of the battery, comprising a charging control terminal connected to the control end of the charging power switch, a discharging control terminal connected to the control end of the discharging power switch, and a charger detection terminal connected to the charging negative terminal CH-, the charger detection terminal being used to obtain a voltage of the charging negative terminal CH-, detecting whether the charging negative terminal CH- is connected to a charger according to the voltage of the charger detection terminal, and when it is detected that the charging negative terminal CH- is connected to a charger, the discharging power switch is controlled to be cut off through the discharging control terminal.

[0008] In a further embodiment, the battery protection system further includes: a resistor RCH connected between the load / charging positive terminal and the charging negative terminal CH-; a first unidirectional conduction module connected between the charging negative terminal CH- and the negative electrode of the battery and connected in series with the charging power switch, the first unidirectional conduction module unidirectionally conducts from the negative electrode of the battery to the charging negative terminal CH-, the first unidirectional conduction module prevents current from flowing from the charging negative terminal CH- to the negative electrode of the battery, when the charging negative terminal CH- is not connected to a charger, the voltage of the charging negative terminal CH- will be pulled up by the load / charging positive terminal through the resistor RCH, and when the charging negative terminal CH- is connected to the charger, the voltage of the charging negative terminal CH- will be pulled down by the charger.

[0009] In a further embodiment, the battery protection system further includes: a current detection resistor RS connected between the negative electrode of the battery and a node A, wherein the discharge power switch is connected between the node A and the negative terminal P- of the load, the charging power switch and the first unidirectional conduction module are connected in series between the node A and the negative charging terminal CH-, the battery protection circuit further includes a current detection terminal VS, the current detection terminal VS is connected to the node A or the node B between the node A and the first unidirectional conduction module, the battery protection circuit determines whether the charging is overcurrent or the discharging is overcurrent based on the voltage of the current detection terminal VS, when the charging is overcurrent, the battery protection circuit controls the charging power switch to be turned off through the charging output terminal, when the discharging is overcurrent, the battery protection circuit controls the discharging power switch to be turned off through the discharging output terminal, when charging protection is not required, the battery protection circuit controls the charging power switch to be turned on through the charging output terminal, and when discharging protection is not required, the battery protection circuit controls the discharging power switch to be turned on through the discharging output terminal.

[0010] The battery protection system also includes: an auxiliary charging power switch connected between the negative electrode of the battery and the negative terminal P- of the load and connected in series with the discharge power switch; a second unidirectional conduction module connected between the charging control terminal and the control terminal of the auxiliary charging power switch and unidirectionally conducting from the charging control terminal to the control terminal of the auxiliary charging power switch; a resistor R4 connected between the control terminal of the auxiliary charging power switch and the negative terminal P- of the load; a third unidirectional conduction module connected between the charging control terminal and the control terminal of the charging power switch and unidirectionally conducting from the charging control terminal to the control terminal of the charging power switch; and a resistor R2 connected between the control terminal of the charging power switch and the negative charging terminal CH-.

[0011] Compared with the prior art, the present invention uses an independent load negative terminal P- and charging negative terminal CH- to isolate the charger from the load. After the charger is connected, the battery stops discharging the load, and the charger does not supply power to the load, thereby eliminating the risk of charger overload and achieving effective charging of the battery.

Brief Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0013] Figure 1 A circuit diagram of a battery protection system in the prior art;

[0014] Figure 2 is a circuit diagram of a battery protection system in a first embodiment of the present invention;

[0015] Figure 3 is a circuit diagram of a battery protection system in a second embodiment of the present invention;

[0016] Figure 4 is a circuit diagram of a battery protection system in a third embodiment of the present invention;

[0017] Figure 5 is a circuit diagram of a battery protection system in a fourth embodiment of the present invention; and

[0018] Figure 6 FIG. 4 is a circuit diagram of a battery protection system in a fifth embodiment of the present invention. [Specific implementation method]

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0021] The present invention provides a battery protection system. When the battery protection system is physically connected to a load, after the charger is connected, the battery stops discharging to the load and the charger does not supply power to the load, thereby eliminating the risk of charger overload and achieving effective charging of the battery.

[0022] Figure 2 FIG. 1 is a circuit diagram of a battery protection system in a first embodiment of the present invention. Figure 3 FIG. 4 is a circuit diagram of a battery protection system in a second embodiment of the present invention. Figure 4 is a circuit diagram of a battery protection system in a third embodiment of the present invention; Figure 5 FIG. 4 is a circuit diagram of a battery protection system in a fourth embodiment of the present invention.

[0023] like Figure 2-5As shown, the battery protection system 200 includes: a battery Battery, a charging power switch MNC, a discharging power switch MND; a load / charging positive terminal P+ / CH+ connected to the positive electrode of the battery; a load negative terminal P- connected to the negative electrode B- of the battery through the discharging power switch MND; a charging negative terminal CH- independent of the load negative terminal P-; and a battery protection circuit 210 connected between the positive and negative electrodes of the battery. The charging negative terminal CH- is connected to the negative electrode B- of the battery through the charging power switch MNC. Power is supplied to the load through the load / charging positive electrode P+ / CH+ and the load negative terminal P-, and the charger is connected through the load / charging positive electrode P+ / CH+ and the charging negative terminal CH-. The battery protection circuit 210 includes a charging control terminal CO connected to the control terminal of the charging power switch MNC, a discharging control terminal DO connected to the control terminal of the discharging power switch MND, and a charger detection terminal CHN connected to the charging negative terminal CH-. The charger detection terminal CHN is used to obtain the voltage of the negative charging terminal CH-. The battery protection circuit 210 detects whether the negative charging terminal CH- is connected to the charger according to the voltage of the charger detection terminal CHN. When it is detected that the negative charging terminal CH- is connected to the charger, the discharge power switch MND is controlled to be turned off through the discharge control terminal DO. In this way, after the charger is connected, the battery stops discharging to the load, and the charger does not supply power to the load, thereby eliminating the risk of charger overload and realizing effective charging of the battery.

[0024] The battery may be a single cell or a plurality of cascaded cells.

[0025] like Figure 2-5 As shown, the battery protection system 200 also includes: a resistor RCH connected between the load / charging positive terminal P+ / CH+ and the charging negative terminal CH-; a first unidirectional conduction module 220 connected between the charging negative terminal CH- and the negative electrode B- of the battery and connected in series with the charging power switch MNC. The first unidirectional conduction module 220 conducts unidirectionally from the negative electrode B- of the battery to the charging negative terminal CH-. When the charging negative terminal CH- is not connected to a charger, the voltage of the charging negative terminal CH- will be pulled up by the load / charging positive terminal P+ / CH+ through the resistor RCH, and the first unidirectional conduction module 220 prevents current from flowing from the charging negative terminal CH- to the negative electrode B- of the battery. When the charging negative terminal CH- is connected to the charger, the voltage of the charging negative terminal CH- will be pulled down by the charger. In this way, by detecting the voltage of the charger detection terminal CHN, it is possible to detect whether the charging negative terminal CH- is connected to a charger.

[0026] More specifically, when the voltage difference between the voltage at the charger detection terminal CHN and the voltage at the load / charging positive terminal P+ / CH+ is less than a predetermined voltage threshold, the battery protection circuit 210 considers that the charging negative terminal CH- is not connected to the charger, and when the voltage difference between the voltage at the charger detection terminal CHN and the voltage at the load / charging positive terminal P+ / CH+ is greater than the predetermined voltage threshold, the charging negative terminal CH- is considered to be connected to the charger. For example, the predetermined voltage threshold is between 0.5V0 and 4.5V, which can be determined as needed. In another embodiment, the battery protection circuit 210 can also directly compare the voltage at the charger detection terminal CHN with another predetermined voltage threshold, and when the voltage at the charger detection terminal CHN is higher than another predetermined voltage threshold, it is considered that the charger is not connected, and when the voltage at the charger detection terminal CHN is lower than another predetermined voltage threshold, it is considered that the charger is connected.

[0027] In one example, the first unidirectional conduction module 220 is a diode D1, an anode of the diode D1 is connected to the negative electrode B- of the battery, and a cathode of the diode D1 is connected to the negative charging terminal CH-.

[0028] like Figure 2-5 As shown, the battery protection system 200 further includes: a current detection resistor RS and a current detection terminal VS connected between the negative electrode B- of the battery and the node A, wherein the discharge power switch MND is connected between the node A and the load negative terminal P-, and the charging power switch MNC and the first unidirectional conduction module 220 are connected in series between the node A and the charging negative terminal CH-. The current detection terminal VS is connected to the node A or the node B between the node A and the first unidirectional conduction module 220.

[0029] The battery protection circuit 210 determines whether there is a charging overcurrent or a discharging overcurrent based on the voltage of the current detection terminal VS. When the charging overcurrent occurs, the battery protection circuit 210 controls the charging power switch MNC to be turned off through the charging output terminal CO. When the discharging overcurrent occurs, the battery protection circuit 210 controls the discharging power switch MND to be turned off through the discharging output terminal DO. When charging protection is not required, the battery protection circuit 210 controls the charging power switch MNC to be turned on through the charging output terminal CO, and when discharging protection is not required, the battery protection circuit 210 controls the discharging power switch MND to be turned on through the discharging output terminal DO.

[0030] The charging power switch may be an NMOS transistor MNC, the source of which is connected to the negative charging terminal CH-, the drain of which is connected to the negative electrode of the battery, and the gate of which is the control terminal of the charging power switch. The discharging power switch may be an NMOS transistor MND, the source of which is connected to the negative electrode of the battery, the drain of which is connected to the negative load terminal P-, and the gate of which is the control terminal of the discharging power switch.

[0031] Specifically, when the charging control terminal CO is at a high level, the charging power switch MNC is turned on to allow charging, and when the charging control terminal CO is at a low level, the charging power switch MNC is turned off to prohibit charging. In order to ensure that the charging power switch MNC can be turned off, the low level of the charging control terminal CO is the voltage of the negative charging terminal CH- when the charger is connected, and this voltage is the voltage obtained by the battery protection circuit 210 through the charger detection terminal CHN. The high level of the charging control terminal can turn on the charging power switch.

[0032] Specifically, when the discharge control terminal DO is at a high level, the discharge power switch MND is turned on to allow discharge, and when the discharge control terminal DO is at a low level, the discharge power switch MND is turned on to prohibit discharge. The low level of the discharge control terminal DO is the negative electrode B-voltage of the battery, and the high level of the discharge control terminal DO is the level that can turn on the discharge power switch MND.

[0033] like Figure 2-5 As shown, the battery protection system 200 also includes: an auxiliary current detection resistor RSC connected in series between the first unidirectional conduction module 210 and the node A, and the current detection terminal VS is connected to the node B between the auxiliary current detection resistor RSC and the first unidirectional conduction module 220.

[0034] When the battery is discharging, the discharge current flows through the discharge power switch MND and the current detection resistor RS, and the voltage of the current detection terminal VS can reflect the voltage drop formed by the discharge current flowing through the current detection resistor RS, thereby realizing discharge overcurrent protection and short circuit protection based on the voltage of the current detection terminal VS. When the discharge is overcurrent or short-circuited, the battery protection circuit 210 controls the discharge power switch MND to be turned off through the discharge output terminal DO.

[0035] When the battery is charged, the charging current flows through the current detection resistor RS and the auxiliary current detection resistor RSC, and the voltage of the current detection terminal VS can reflect the total voltage drop formed by the charging current flowing through the current detection resistor RS and the auxiliary current detection resistor RSC, thereby realizing charging overcurrent protection. The auxiliary current detection resistor RS provides the possibility for flexibly adjusting the charging overcurrent threshold. In other embodiments, the auxiliary current detection resistor RSC may not be set, and the charging current detection voltage drop is calculated as RSC=0. At this time, the current detection terminal VS can be connected to the node A, or to the node B between the node A and the first unidirectional conduction module 220.

[0036] like Figure 2-5 As shown, the battery protection circuit further includes a detection terminal VM, a current limiting resistor RCHN connected between the charger detection terminal CHN and the charging negative terminal CH-, a current limiting resistor RVM connected between the detection terminal VM and the load negative terminal P-, and a current limiting resistor RVS connected between the current detection terminal VS and the node B. The detection terminal VM is used to obtain the voltage of the load negative terminal P-. In some embodiments, the current limiting resistor RVS may not be set, such as Figure 3-5 Similarly, in some embodiments, depending on the specific application, the current limiting resistor RCHN and the current limiting resistor RVM may not be provided.

[0037] Figure 2-Figure 5 The differences among the various embodiments are that: the connection position of the current detection terminal VS is different; the positions of the auxiliary current detection resistor RSC, the charging power switch MNC and the first unidirectional conduction module 220 connected in series between the node A and the negative charging terminal CH- are changed. Figure 2 and Figure 3 Between the middle node A and the negative charging terminal CH- are the auxiliary current detection resistor RSC, the charging power switch MNC and the first unidirectional conduction module 220. Figure 4 The charging power switch MNC, the auxiliary current detection resistor RSC and the first unidirectional conduction module 220 are arranged between the middle node A and the negative charging terminal CH− in sequence. Figure 5 Between the middle node A and the negative charging terminal CH- are the auxiliary current detection resistor RSC, the first unidirectional conduction module 220 and the charging power switch MNC. However, no matter how it changes, the current detection terminal VS is connected to the node between the auxiliary current detection resistor RSC and the first unidirectional conduction module 220 (referred to as node B). As described above, when the auxiliary current detection resistor RSC is not provided, the current detection terminal VS is connected to the node A or the node between the node A and the first unidirectional conduction module 220 (referred to as node B).

[0038] Figure 6 FIG. 4 is a circuit diagram of a battery protection system in a fifth embodiment of the present invention. Figure 6 The circuit structure and Figure 2 The similarities between the circuit structures of the battery protection systems in the present invention will not be repeated here. The following mainly introduces the differences between the two.

[0039] like Figure 6 As shown, the battery protection system 200 includes: an auxiliary charging power switch MNC1 connected between the negative electrode B- of the battery and the negative electrode P- of the load and connected in series with the discharge power switch MND; a second unidirectional conduction module 230 connected between the charging control terminal CO and the control terminal of the auxiliary charging power switch MNC1 and unidirectionally conducting from the charging control terminal CO to the control terminal of the auxiliary charging power switch MNC1; a resistor R4 connected between the control terminal of the auxiliary charging power switch MNC1 and the negative electrode P- of the load; a third unidirectional conduction module 240 connected between the charging control terminal CO and the control terminal of the charging power switch MNC and unidirectionally conducting from the charging control terminal CO to the control terminal of the charging power switch MNC; and a resistor R2 connected between the control terminal of the charging power switch MNC and the negative charging terminal CH-.

[0040] More specifically, the auxiliary charging power switch MNC1 is connected between the node A and the load negative terminal P-.

[0041] When charging is allowed, the charging control terminal CO is pulled up to a high level, so that the auxiliary charging power switch MNC1 and the charging power switch MNC are turned on to allow charging.

[0042] When charging needs to be prohibited, the charging control terminal CO is not pulled up to a high level. At this time, if the load negative terminal P- is connected to a charger, the control terminal of the auxiliary charging power switch MNC1 is pulled down by the load negative terminal P-, so that the auxiliary charging power switch MNC1 is disconnected to prohibit charging from the load negative terminal P-. If the charging negative terminal CH- is connected to a charger, the control terminal of the charging power switch MNC is pulled down by the charging negative terminal CH-, so that the charging power switch is disconnected to prohibit charging from the charging negative terminal CH-. In this way, not only charging from the charging negative terminal CH- can be prohibited, but also charging from the load negative terminal P- can be prohibited, further improving the battery protection safety.

[0043] like Figure 6As shown, the battery protection system 200 further includes: a resistor R3 connected between the second unidirectional conduction module 230 and the control end of the auxiliary charging power switch MNC1; and a resistor R1 connected between the third unidirectional conduction module 240 and the control end of the charging power switch MNC1. In some embodiments, the resistor R3 and the resistor R1 may not be provided.

[0044] In another embodiment, one of the resistors R2 may also be connected to the positive electrode C of the first unidirectional conduction module 220 instead of being connected to the negative charging terminal CH-. Of course, in this connection mode, the resistor R2 is still connected to the negative charging terminal CH- through the first unidirectional conduction module 220.

[0045] exist Figure 6 In the embodiment, the second unidirectional conduction module 230 is a diode D2, and the third unidirectional conduction module 240 is a diode D3, wherein the anode of the diode D2 is connected to the charging control terminal CO, the cathode of the diode D2 is connected to the control terminal of the auxiliary charging power switch MNC1 through a resistor R3, and the cathode of the diode D3 is connected to the control terminal of the charging power switch MNC through a resistor R1. In other embodiments, the anode of the diode D2 can be connected to the cathode of the diode D3, or the anode of the diode D3 can be connected to the cathode of the diode D2, as long as the second unidirectional conduction module 230 and the third unidirectional conduction module 240 can ensure that the control terminal of the auxiliary charging power switch MNC1 and the control terminal of the charging power switch MNC are bidirectionally cut off. In this way, the diodes D2 and D3 can prevent the different potentials of P- and CH- from interfering with each other and causing the failure of the charging protection when charging is prohibited.

[0046] The present invention uses an independent load negative terminal P- and charging negative terminal CH- to isolate the charger from the load. When the battery protection system remains physically connected to the load, after the charger is connected, the battery stops discharging to the load, and the charger does not supply power to the load, thereby eliminating the risk of charger overload and achieving effective charging of the battery.

[0047] In the present invention, words such as "connect", "connected", "connect", "connected", "coupled", etc., which indicate electrical connection, indicate direct or indirect electrical connection unless otherwise specified. The direct electrical connection indicates a direct connection between two or more objects without any intervening objects, and the indirect electrical connection indicates a connection between two or more objects with one or more objects (such as electrical components or electrical units such as resistors, capacitors, inductors, switches, filters, etc.) intervening.

[0048] It should be noted that any changes made by those skilled in the art to the specific embodiments of the present invention do not deviate from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the above specific embodiments.

Claims

1. A battery protection system, characterized in that: It includes: Battery, charging power switch, discharging power switch; A load / charging positive terminal connected to the positive electrode of the battery; A load negative terminal P-, which is connected to the negative electrode of the battery through the discharge power switch; A negative charging terminal CH-, which is independent of the negative load terminal P- and is connected to the negative electrode of the battery through the charging power switch; A battery protection circuit connected between the positive and negative electrodes of the battery comprises a charging control terminal connected to the control terminal of the charging power switch, a discharging control terminal connected to the control terminal of the discharging power switch, and a charger detection terminal connected to the charging negative terminal CH-, wherein the charger detection terminal is used to obtain the voltage of the charging negative terminal CH-, detect whether the charging negative terminal CH- is connected to a charger according to the voltage of the charger detection terminal, and control the discharging power switch to be cut off through the discharging control terminal when it is detected that the charging negative terminal CH- is connected to a charger.

2. The battery protection system according to claim 1, characterized in that: It also includes: A resistor RCH connected between the load / charging positive terminal and the charging negative terminal CH-; A first unidirectional conduction module connected between the negative charging terminal CH- and the negative electrode of the battery and connected in series with the charging power switch, wherein the first unidirectional conduction module conducts unidirectionally from the negative electrode of the battery to the negative charging terminal CH-, and the first unidirectional conduction module prevents current from flowing from the negative charging terminal CH- to the negative electrode of the battery, When the negative charging terminal CH- is not connected to a charger, the voltage of the negative charging terminal CH- will be pulled up by the load / positive charging terminal through the resistor RCH. When the negative charging terminal CH- is connected to the charger, the voltage of the negative charging terminal CH- will be pulled down by the charger.

3. The battery protection system according to claim 2, characterized in that: When the voltage difference between the voltage at the charger detection terminal and the voltage at the load / charging positive terminal is less than a predetermined voltage threshold, the battery protection circuit considers that the charging negative terminal CH- is not connected to the charger; when the voltage difference between the voltage at the charger detection terminal and the voltage at the load / charging positive terminal is greater than the predetermined voltage threshold, the charging negative terminal CH- is considered to be connected to the charger; or, The battery protection circuit directly compares the voltage of the charger detection terminal with another predetermined voltage threshold. When the voltage of the charger detection terminal is higher than the other predetermined voltage threshold, it is considered that the charger is not connected. When the voltage of the charger detection terminal is lower than the other predetermined voltage threshold, it is considered that the charger is connected.

4. The battery protection system according to claim 2, characterized in that: It also includes: A current detection resistor RS is connected between the negative electrode of the battery and the node A, wherein the discharge power switch is connected between the node A and the load negative terminal P-, and the charging power switch and the first unidirectional conduction module are connected in series between the node A and the charging negative terminal CH-, The battery protection circuit further includes a current detection terminal VS, wherein the current detection terminal VS is connected to the node A or a node B between the node A and the first unidirectional conduction module. The battery protection circuit determines whether charging overcurrent or discharging overcurrent occurs based on the voltage of the current detection terminal VS. When charging overcurrent occurs, the battery protection circuit controls the charging power switch to be turned off through the charging output terminal. When discharging overcurrent occurs, the battery protection circuit controls the discharging power switch to be turned off through the discharging output terminal. When charging protection is not required, the battery protection circuit controls the charging power switch to be turned on through the charging output end, and when discharging protection is not required, the battery protection circuit controls the discharging power switch to be turned on through the discharging output end.

5. The battery protection system according to claim 4, characterized in that: It also includes: An auxiliary current detection resistor is connected in series between the first unidirectional conduction module and the node A, wherein the current detection terminal VS is connected to a node B between the auxiliary current detection resistor and the first unidirectional conduction module.

6. The battery protection system according to claim 5, characterized in that: The battery protection circuit further includes a detection terminal VM, which is connected to the load negative terminal P- and is used to obtain the voltage of the load negative terminal P-. It also includes: A current limiting resistor RCHN connected between the charger detection terminal and the negative charging terminal CH-; A current limiting resistor RVM connected between the detection terminal VM and the load negative terminal P-; A current limiting resistor RVS is connected between the current detection terminal VS and the node B.

7. The battery protection system according to claim 1, characterized in that: When the charging control terminal is at a high level, the charging power switch is turned on to allow charging, and when the charging control terminal is at a low level, the charging power switch is turned off to prohibit charging. The low level of the charging control terminal is the voltage of the negative charging terminal CH- when the charger is connected, and the high level of the charging control terminal can turn on the charging power switch. When the discharge control terminal is at a high level, the discharge power switch is turned on to allow discharge, and when the discharge control terminal is at a low level, the discharge power switch is turned on to prohibit discharge. The low level of the discharge control terminal is the negative electrode voltage of the battery, and the high level of the discharge control terminal is the level that can turn on the discharge power switch.

8. The battery protection system according to claim 1, characterized in that: The charging power switch is an NMOS transistor MNC, the source of the NMOS transistor MNC is connected to the negative charging terminal CH-, the drain of the NMOS transistor MNC is connected to the negative electrode of the battery, and the gate of the NMOS transistor MNC is the control terminal of the charging power switch; The discharge power switch is an NMOS transistor MND, a source of the NMOS transistor MND is connected to the negative electrode of the battery, a drain of the NMOS transistor MND is connected to the negative electrode of the load P-, and a gate of the NMOS transistor MND serves as a control terminal of the discharge power switch.

9. The battery protection system according to any one of claims 1 to 8, characterized in that: It includes: an auxiliary charging power switch connected between the negative electrode of the battery and the negative terminal P- of the load and connected in series with the discharge power switch; A second unidirectional conduction module connected between the charging control terminal and the control terminal of the auxiliary charging power switch and unidirectionally conducting from the charging control terminal to the control terminal of the auxiliary charging power switch; A resistor R4 connected between the control terminal of the auxiliary charging power switch and the negative terminal P- of the load; a third unidirectional conduction module connected between the charging control terminal and the control terminal of the charging power switch and unidirectionally conducting from the charging control terminal to the control terminal of the charging power switch; A resistor R2 is connected between the control terminal of the charging power switch and the negative charging terminal CH-.

10. The battery protection system according to claim 9, characterized in that: The second unidirectional conduction module and the third unidirectional conduction module bidirectionally cut off the control end of the auxiliary charging power switch and the control end of the charging power switch.

11. The battery protection system according to claim 9, characterized in that: When charging is allowed, the charging control terminal is pulled up to a high level, so that the auxiliary charging power switch and the charging power switch are turned on. When the charging prohibition protection of the battery protection circuit is triggered, the charging control terminal is not pulled up to a high level. If the charger is connected to the load negative terminal P-, the control terminal of the auxiliary charging power switch is pulled down by the load negative terminal P-, thereby disconnecting the auxiliary charging power switch. If the charger is connected to the charging negative terminal CH-, the control terminal of the charging power switch is pulled down by the charging negative terminal CH-, thereby disconnecting the charging power switch.

12. The battery protection system according to claim 9, characterized in that: It also includes: A resistor R3 connected between the second unidirectional conduction module and the control end of the auxiliary charging power switch; A resistor R1 is connected between the third unidirectional conduction module and the control end of the charging power switch.

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