Anti-overvoltage charging detection circuit for blind charging

Abstract

The utility model discloses an anti-overvoltage charging detection circuit for blind charging. The anti-overvoltage charging detection circuit comprises a signal detection circuit, a signal switching circuit and an MCU module. The signal detection circuit detects whether an external charger is connected or not; the MCU module controls the signal switching circuit to be switched on according to a detection result output by the signal detection circuit; the signal switching circuit transmits a to-be-detected signal of an external charger to the signal detection circuit; the signal detection circuit performs matching judgment on a to-be-detected signal of an external charger and the voltage of the lithium battery pack; and the MCU module controls the on-off of the charging and discharging switch MOS tube according to the judgment result of the signal detection circuit, so as to control the charging and discharging of the battery. After the external charger is connected, whether the output of the external charger is matched with the voltage of the lithium battery pack or not is judged through the signal detection circuit, then the judgment result is sent to the MCU module, the MCU module controls whether to open the charging and discharging switch MOS tube or not, and the situation that the output voltage of the external charger is too high and the battery is damaged can be avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery blind charging overvoltage protection, and particularly relates to an overvoltage charging detection circuit for blind charging. Background Art

[0002] Existing lithium battery chargers are generally divided into two types. One is a charger with a standard charging communication protocol, that is, the charging MOS switch is turned on after the battery internal protection board BMS and the charger shake hands successfully. The advantage of this is that the charger will not be mismatched and the battery will not be damaged due to inappropriate voltage; however, the disadvantages are also obvious. That is, the charger is not universal and must use the standard protocol to be applicable. Another disadvantage is that the cost of this charger is relatively high.

[0003] Another widely used charging method is blind charging. That is, after plugging in the mains power, the charger can output the charging voltage. Such a charger can generally charge uniformly as long as the number of battery strings and the materials of the lithium battery packs are the same. This charging method has wide universality and low cost; however, the disadvantages are also obvious. It may mis-use the charger. For example, using a 72V charger to directly charge a 48V battery. In the existing lithium-ion battery system, after the protection board BMS of the battery is made into a finished product, its charging and discharging are in the open state. After connecting to the charger, the battery will pull down the voltage of the charger and clamp the output voltage of the charger (Clamping: The battery pulls down the voltage of the charger, causing the charger to enter the constant current charging mode, while the charger is in the constant voltage state when it is no-load). When connecting to the charger, no matter how high the output voltage of the charger is, it will charge the battery, and the protection board BMS cannot judge how much the output voltage of the charger is and whether it will damage the battery.

[0004] Therefore, it is urgent to propose a new overvoltage charging detection circuit for blind charging to detect overvoltage charging of the equipment for blind charging, so as to prevent the lithium-ion battery from being damaged due to too high voltage of the external charger. Summary of the Utility Model

[0005] In order to solve the above problems existing in the prior art, the utility model provides an overvoltage charging detection circuit for blind charging. The technical problems to be solved by the utility model are realized through the following technical solutions:

[0006] An overvoltage charging detection circuit for blind charging, comprising:

[0007] A signal detection circuit, a signal switching circuit and an MCU module; wherein,

[0008] The signal detection circuit is used to detect whether an external charger is connected and transmit the detection result to the MCU module;

[0009] The MCU module is used to control the conduction of the signal switching circuit according to the detection result;

[0010] The signal switching circuit is used to transmit the signal to be measured of the external charger to the signal detection circuit after conduction;

[0011] The signal detection circuit is further used to match and judge the signal to be measured of the external charger with the voltage of the lithium battery pack, and output the judgment result to the MCU module;

[0012] The MCU module is further used to control the on-off of the charging and discharging switch MOS transistor between the external charger and the lithium battery pack according to the judgment result, so as to realize the control of battery charging and discharging.

[0013] Preferably, the signal switching circuit includes:

[0014] The first NPN transistor Q1, resistor R2, resistor R3, zener diode Z1 and signal relay; wherein,

[0015] The emitter of the first NPN transistor Q1 is grounded, the collector of the first NPN transistor Q1 is connected to the coil current output end of the signal relay, and the base of the first NPN transistor Q1 is connected to the first end of the resistor R2;

[0016] The second end of the resistor R2 is connected to the output end of the MCU module;

[0017] The first end of the resistor R3 is connected to the emitter of the first NPN transistor Q1, and the second end of the resistor R3 is connected to the first end of the resistor R2;

[0018] The anode of the zener diode Z1 is connected to the normally open end of the signal relay, and the cathode of the zener diode Z1 is grounded;

[0019] The coil current input end of the signal relay is connected to VCC, the normally closed end of the signal relay is grounded, and the output end of the signal relay is used as the output end of the signal switching circuit and is connected to the signal detection circuit.

[0020] Preferably, the signal relay includes:

[0021] Normally closed switch NC, normally open switch NO, COM relay and coil; wherein,

[0022] The first end of the normally closed switch NC is connected to the common end of the COM relay, and the second end of the normally closed switch NC is used as the normally closed end of the signal relay;

[0023] The first end of the normally open switch NO is connected to the common end of the COM relay, and the second end of the normally open switch NO serves as the normally open end of the signal relay;

[0024] The first end of the coil serves as the coil current input end of the signal relay, and the second end of the coil serves as the coil current output end of the signal relay;

[0025] The common end of the COM relay serves as the output end of the signal relay.

[0026] Preferably, the signal detection circuit includes:

[0027] The second NPN transistor Q2, the third PNP transistor Q3, the resistor R4, the resistor R5, the resistor R6, the resistor R7, the resistor R8, the third diode D3, and the fourth diode D4; wherein,

[0028] The emitter of the second NPN transistor Q2 is connected to the anode of the third diode D3, the collector of the second NPN transistor Q2 is connected to the cathode of the fourth diode D4, and the base of the second NPN transistor Q2 is connected to the first end of the resistor R4;

[0029] The emitter of the third PNP transistor Q3 is connected to VCC, the collector of the third PNP transistor Q3 is connected to the first end of the resistor R8, and the base of the third PNP transistor Q3 is connected to the second end of the resistor R6;

[0030] The second end of the resistor R4 serves as the input end of the signal detection circuit and is connected to the output end of the signal switching circuit;

[0031] The first end of the resistor R5 is connected to the second end of the resistor R6, and the second end of the resistor R5 is connected to the anode of the fourth diode D4;

[0032] The first end of the resistor R6 is connected to the emitter of the third PNP transistor Q3;

[0033] The first end of the resistor R7 serves as the output end of the signal detection circuit, and the second end of the resistor R7 is connected to the first end of the resistor R8;

[0034] The second end of the resistor R8 is grounded;

[0035] The cathode of the third diode D3 is connected to the PACK- terminal.

[0036] Preferably, the process of the signal detection circuit detecting whether an external charger is connected and transmitting the detection result to the MCU module includes:

[0037] When an external charger is connected, the positive electrode of the external charger is connected to the positive electrode of the battery. The voltage of the external charger is greater than the voltage of the battery. The potential of the GND terminal is higher than the potential of the PACK- terminal. The second NPN transistor Q2 conducts, the third PNP transistor Q3 conducts, and the signal detection circuit outputs a high-level signal as the detection result to the MCU module;

[0038] When the external charger is not connected, the PACK- terminal is floating, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a low-level signal as the detection result to the MCU module.

[0039] Preferably, the process of the signal detection circuit matching and judging the signal to be measured of the external charger with the voltage of the lithium battery pack and outputting the judgment result to the MCU module includes:

[0040] When the sum of the potential of the GND terminal and the voltage of the zener diode Z1 is greater than the potential of the PACK- terminal, the second NPN transistor Q2 conducts, the third PNP transistor Q3 conducts, and the signal detection circuit outputs a signal of rejecting charging as the judgment result to the MCU module;

[0041] When the sum of the potential of the GND terminal and the voltage of the zener diode Z1 is less than or equal to the potential of the PACK- terminal, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a signal of allowing charging as the judgment result to the MCU module.

[0042] Preferably, the process of the MCU module controlling the on / off of the charging and discharging switch MOS transistor between the external charger and the lithium battery pack according to the judgment result to realize the control of battery charging and discharging includes:

[0043] When the judgment result received by the MCU module is a signal of rejecting charging, the MCU module controls the charging and discharging switch MOS transistor to turn off, preventing the external charger from charging the battery;

[0044] When the judgment result received by the MCU module is a signal of allowing charging, the MCU module controls the charging and discharging switch MOS transistor to turn on, allowing the external charger to charge the battery.

[0045] Preferably, the MCU module includes a single-chip microcomputer and a peripheral circuit.

[0046] The beneficial effects of the present utility model:

[0047] In the solution provided by the embodiments of the present utility model, after the external charger is connected, the signal detection circuit first determines whether the output of the external charger matches the voltage of the lithium battery pack, and then sends the determination result to the MCU module. The MCU module controls whether to turn on the charge and discharge switch MOS tube, which can prevent the battery from being damaged due to the too high output voltage of the external charger. Description of the Drawings

[0048] Figure 1 FIG. is a specific circuit schematic diagram of an overvoltage charging detection circuit for blind charging provided by the embodiments of the present utility model.

[0049] Reference Signs:

[0050] 10 - Signal detection circuit; 20 - Signal switching circuit. Detailed Embodiments

[0051] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings of the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0052] In order to achieve the purpose of detecting overvoltage charging for the equipment of blind charging to prevent the lithium-ion battery from being damaged due to the too high voltage of the external charger, the embodiments of the present utility model provide an overvoltage charging detection circuit for blind charging, which may include:

[0053] A signal detection circuit, a signal switching circuit, and an MCU module; wherein,

[0054] The signal detection circuit is used to detect whether the external charger is connected and transmit the detection result to the MCU module;

[0055] The MCU module is used to control the signal switching circuit to conduct according to the detection result;

[0056] The signal switching circuit is used to transmit the signal to be measured of the external charger to the signal detection circuit after conduction;

[0057] The signal detection circuit is further used to match and judge the signal to be measured of the external charger with the voltage of the lithium battery pack, and output the judgment result to the MCU module;

[0058] The MCU module is further used to control the on-off of the charge and discharge switch MOS tube between the external charger and the lithium battery pack according to the judgment result, so as to realize the control of battery charging and discharging.

[0059] In the solution provided by the embodiments of the present utility model, the working process of the overvoltage protection charging detection circuit may include: First, use the signal detection circuit to detect whether an external charger is connected, and transmit the detection result to the MCU module; if it is detected that the external charger is connected, the MCU module controls the signal switching circuit to conduct; the signal switching circuit transmits the signal to be detected of the external charger to the signal detection circuit; the signal detection circuit matches and judges the signal to be detected of the external charger with the voltage of the lithium battery pack, and outputs the judgment result to the MCU module; when the judgment result is that charging is allowed, the MCU module controls the charge and discharge switch MOS transistor between the external charger and the lithium battery pack to conduct, and at this time, the external charger starts to charge the lithium battery pack; when the judgment result is that charging is refused, the MCU module controls the charge and discharge switch MOS transistor between the external charger and the lithium battery pack to turn off, and at this time, the external charger cannot charge the lithium battery pack.

[0060] For ease of understanding, each module of an overvoltage protection charging detection circuit for blind charging will be introduced separately below.

[0061] Signal detection circuit

[0062] The signal detection circuit is as Figure 1 shown in 10 and may include:

[0063] The second NPN transistor Q2, the third PNP transistor Q3, the resistor R4, the resistor R5, the resistor R6, the resistor R7, the resistor R8, the third diode D3, and the fourth diode D4; among them,

[0064] The emitter of the second NPN transistor Q2 is connected to the anode of the third diode D3, the collector of the second NPN transistor Q2 is connected to the cathode of the fourth diode D4, and the base of the second NPN transistor Q2 is connected to the first end of the resistor R4;

[0065] The emitter of the third PNP transistor Q3 is connected to VCC, the collector of the third PNP transistor Q3 is connected to the first end of the resistor R8, and the base of the third PNP transistor Q3 is connected to the second end of the resistor R6;

[0066] The second end of the resistor R4 serves as the input end of the signal detection circuit and is connected to the output end of the signal switching circuit;

[0067] The first end of the resistor R5 is connected to the second end of the resistor R6, and the second end of the resistor R5 is connected to the anode of the fourth diode D4;

[0068] The first end of the resistor R6 is connected to the emitter of the third PNP transistor Q3;

[0069] The first end of the resistor R7 serves as the output end of the signal detection circuit, and the second end of the resistor R7 is connected to the first end of the resistor R8;

[0070] The second terminal of resistor R8 is grounded;

[0071] The cathode of the third diode D3 is connected to the PACK- terminal.

[0072] The signal detection circuit is used to detect whether an external charger is connected and to match and judge the signal to be measured of the external charger with the voltage of the lithium battery pack.

[0073] Specifically, the process by which the signal detection circuit detects whether an external charger is connected and transmits the detection result to the MCU module may include:

[0074] When the external charger is connected, the positive electrode of the external charger is connected to the positive electrode of the battery, the voltage of the external charger is greater than the voltage of the battery, the potential of the GND terminal is higher than the potential of the PACK- terminal, the second NPN transistor Q2 conducts, the third PNP transistor Q3 conducts, and the signal detection circuit outputs a high-level signal as the detection result to the MCU module;

[0075] When the external charger is not connected, the PACK- terminal is floating, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a low-level signal as the detection result to the MCU module.

[0076] Specifically, the process by which the signal detection circuit matches and judges the signal to be measured of the external charger with the voltage of the lithium battery pack and outputs the judgment result to the MCU module may include:

[0077] When the sum of the potential of the GND terminal and the voltage of the zener diode Z1 is greater than the potential of the PACK- terminal, the second NPN transistor Q2 conducts, the third PNP transistor Q3 conducts, and the signal detection circuit outputs a signal for rejecting charging as the judgment result to the MCU module;

[0078] When the sum of the potential of the GND terminal and the voltage of the zener diode Z1 is less than or equal to the potential of the PACK- terminal, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a signal for allowing charging as the judgment result to the MCU module.

[0079] Signal switching circuit

[0080] The signal switching circuit is as Figure 1 shown in 20 and may include:

[0081] The first NPN transistor Q1, resistor R2, resistor R3, zener diode Z1, and signal relay; wherein,

[0082] The emitter of the first NPN transistor Q1 is grounded, the collector of the first NPN transistor Q1 is connected to the coil current output terminal of the signal relay, and the base of the first NPN transistor Q1 is connected to the first end of the resistor R2;

[0083] The second end of the resistor R2 is connected to the output terminal of the MCU module;

[0084] The first end of the resistor R3 is connected to the emitter of the first NPN transistor Q1, and the second end of the resistor R3 is connected to the first end of the resistor R2;

[0085] The anode of the zener diode Z1 is connected to the normally open terminal of the signal relay, and the cathode of the zener diode Z1 is grounded;

[0086] The coil current input terminal of the signal relay is connected to VCC, the normally closed terminal of the signal relay is grounded, and the output terminal of the signal relay is used as the output terminal of the signal switching circuit and is connected to the signal detection circuit.

[0087] Specifically, the signal relay may include:

[0088] A normally closed switch NC, a normally open switch NO, a COM relay, and a coil; among them,

[0089] The first end of the normally closed switch NC is connected to the common terminal of the COM relay, and the second end of the normally closed switch NC is used as the normally closed terminal of the signal relay;

[0090] The first end of the normally open switch NO is connected to the common terminal of the COM relay, and the second end of the normally open switch NO is used as the normally open terminal of the signal relay;

[0091] The first end of the coil is used as the coil current input terminal of the signal relay, and the second end of the coil is used as the coil current output terminal of the signal relay;

[0092] The common terminal of the COM relay is used as the output terminal of the signal relay.

[0093] The signal switching circuit is used to transmit the signal to be measured of the external charger to the signal detection circuit after being turned on according to the control of the MCU module.

[0094] MCU module

[0095] The MCU module includes a single-chip microcomputer and peripheral circuits.

[0096] In the single-chip microcomputer and peripheral circuits, the model of the single-chip microcomputer uses an existing single-chip microcomputer chip on the market, and the peripheral circuits use existing circuit designs. For details, please refer to the prior art and will not be described in detail here.

[0097] Specifically, the process of the MCU module controlling the on / off of the charging and discharging switch MOS transistor between the external charger and the lithium battery pack according to the judgment result to achieve the control of battery charging and discharging includes:

[0098] When the judgment result received by the MCU module is a signal of rejecting charging, the MCU module controls the charging and discharging switch MOS transistor to turn off, preventing the external charger from charging the battery;

[0099] When the judgment result received by the MCU module is a signal of allowing charging, the MCU module controls the charging and discharging switch MOS transistor to turn on, allowing the external charger to charge the battery.

[0100] In the default case of the overvoltage charging detection circuit, the control signal output by the MCU module is at a low level. At this time, the first NPN transistor Q1 is cut off, the signal relay does not act, and the normally closed terminal (NC) of the signal relay is connected to the common terminal (COM) of the signal relay. When the signal detection circuit detects the access of the external charger, the control signal output by the MCU module is at a high level. At this time, the first NPN transistor Q1 is turned on, the coil of the signal relay is energized, the normally open terminal (NO) of the signal relay is connected to the common terminal (COM) of the signal relay, and the signal to be measured of the external charger is transmitted to the signal detection circuit through the voltage stabilizing diode Z1.

[0101] During blind charging, after the external charger is connected to the lithium battery pack, it will carry a voltage, and this voltage is higher than the voltage of the lithium battery pack when it is fully charged. Since the positive electrode of the external charger is connected to the positive electrode of the lithium battery pack, and the voltage of the external charger is greater than the voltage of the lithium battery pack, the potential of the GND terminal is higher than the potential of the PACK- terminal. The second NPN transistor Q2 is turned on, and thus the third PNP transistor Q3 is turned on. The signal detection circuit outputs a detection result of a high level, indicating that the external charger is connected at this time. By default, the PACK- terminal is floating, so the second NPN transistor Q2 is cut off, and at the same time the third PNP transistor Q3 is also cut off. The signal detection circuit outputs a detection result of a low level, indicating that the external charger is not connected at this time.

[0102] After detecting the access of the external charger, when the sum of the potential of the GND terminal and the voltage of the voltage stabilizing diode Z1 is greater than the potential of the PACK- terminal, the second NPN transistor Q2 is turned on, the third PNP transistor Q3 is turned on, and the signal detection circuit outputs a signal of rejecting charging as the judgment result to the MCU module. The MCU module controls the charging and discharging switch MOS transistor to turn off, preventing the external charger from charging the battery;

[0103] When the sum of the potential of the GND terminal and the voltage of the voltage stabilizing diode Z1 is less than or equal to the potential of the PACK- terminal, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a signal allowing charging as a judgment result to the MCU module. The MCU module controls the conduction of the charge and discharge switch MOS transistor, allowing the external charger to charge the battery.

[0104] In the solution provided by the embodiment of the present invention, after the external charger is connected, first, the signal detection circuit determines whether the output of the external charger matches the voltage of the lithium battery pack, and then sends the judgment result to the MCU module. The MCU module controls whether to turn on the charge and discharge switch MOS transistor, which can prevent the output voltage of the external charger from being too high and damaging the battery.

[0105] The above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A circuit for detecting overvoltage charging in blind charging, characterized in that, It includes: A signal detection circuit, a signal switching circuit, and an MCU module; among them, The signal detection circuit is used to detect whether an external charger is connected and transmit the detection result to the MCU module; the input end of the signal detection circuit is electrically connected to the output end of the signal switching circuit, and the output end is electrically connected to the input end of the MCU module; The MCU module is used to control the signal switching circuit to conduct according to the detection result; The signal switching circuit is used to transmit the signal to be measured of the external charger to the signal detection circuit after conduction; The signal detection circuit is further used to match and judge the signal to be measured of the external charger with the voltage of the lithium battery pack and output the judgment result to the MCU module; the signal detection circuit includes: A second NPN transistor Q2, a third PNP transistor Q3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a third diode D3, and a fourth diode D4; among them, The emitter of the second NPN transistor Q2 is connected to the anode of the third diode D3, the collector of the second NPN transistor Q2 is connected to the cathode of the fourth diode D4, and the base of the second NPN transistor Q2 is connected to the first end of the resistor R4; The emitter of the third PNP transistor Q3 is connected to VCC, the collector of the third PNP transistor Q3 is connected to the first end of the resistor R8, and the base of the third PNP transistor Q3 is connected to the second end of the resistor R6; The second end of the resistor R4 is used as the input end of the signal detection circuit and is connected to the output end of the signal switching circuit; The first end of the resistor R5 is connected to the second end of the resistor R6, and the second end of the resistor R5 is connected to the anode of the fourth diode D4; The first end of the resistor R6 is connected to the emitter of the third PNP transistor Q3; The first end of the resistor R7 is used as the output end of the signal detection circuit, and the second end of the resistor R7 is connected to the first end of the resistor R8; The second end of the resistor R8 is grounded; The cathode of the third diode D3 is connected to the PACK- terminal; The MCU module is further used to control the on / off of the charge and discharge switch MOS transistor between the external charger and the lithium battery pack according to the judgment result to realize the control of battery charge and discharge.

2. The overvoltage charging detection circuit for blind charging according to claim 1, wherein, The signal switching circuit includes: A first NPN transistor Q1, a resistor R2, a resistor R3, a zener diode Z1, and a signal relay; among them, The emitter of the first NPN transistor Q1 is grounded, the collector of the first NPN transistor Q1 is connected to the coil current output end of the signal relay, and the base of the first NPN transistor Q1 is connected to the first end of the resistor R2; The second end of the resistor R2 is connected to the output end of the MCU module; The first end of the resistor R3 is connected to the emitter of the first NPN transistor Q1, and the second end of the resistor R3 is connected to the first end of the resistor R2; The anode of the voltage stabilizing diode Z1 is connected to the normally open end of the signal relay, and the cathode of the voltage stabilizing diode Z1 is grounded; The coil current input end of the signal relay is connected to VCC, the normally closed end of the signal relay is grounded, and the output end of the signal relay is used as the output end of the signal switching circuit and is connected to the signal detection circuit.

3. The overvoltage charging detection circuit for blind charging according to claim 2, wherein, The signal relay includes: A normally closed switch NC, a normally open switch NO, a COM relay, and a coil; where The first end of the normally closed switch NC is connected to the common end of the COM relay, and the second end of the normally closed switch NC is used as the normally closed end of the signal relay; The first end of the normally open switch NO is connected to the common end of the COM relay, and the second end of the normally open switch NO is used as the normally open end of the signal relay; The first end of the coil is used as the coil current input end of the signal relay, and the second end of the coil is used as the coil current output end of the signal relay; The common end of the COM relay is used as the output end of the signal relay.

4. The overvoltage charging detection circuit for blind charging according to claim 3, wherein, The process by which the signal detection circuit detects whether an external charger is connected and transmits the detection result to the MCU module includes: When an external charger is connected, the positive electrode of the external charger is connected to the positive electrode of the battery, the voltage of the external charger is greater than the voltage of the battery, the potential of the GND terminal is higher than the potential of the PACK- terminal, the second NPN transistor Q2 conducts, the third PNP transistor Q3 conducts, and the signal detection circuit outputs a high-level signal as the detection result to the MCU module; When the external charger is not connected, the PACK- terminal is floating, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a low-level signal as the detection result to the MCU module.

5. The overvoltage charging detection circuit for blind charging according to claim 4, wherein The process by which the signal detection circuit matches and judges the signal to be measured of the external charger with the voltage of the lithium battery pack and outputs the judgment result to the MCU module includes: When the sum of the potential of the GND terminal and the voltage of the voltage stabilizing diode Z1 is greater than the potential of the PACK- terminal, the second NPN transistor Q2 conducts, the third PNP transistor Q3 conducts, and the signal detection circuit outputs a signal of rejecting charging as the judgment result to the MCU module; When the sum of the potential of the GND terminal and the voltage of the voltage stabilizing diode Z1 is less than or equal to the potential of the PACK- terminal, the second NPN transistor Q2 is cut off, the third PNP transistor Q3 is cut off, and the signal detection circuit outputs a signal of allowing charging as the judgment result to the MCU module.

6. The overvoltage charging detection circuit for blind charging according to claim 1, characterized in that The MCU module includes a single-chip microcomputer and a peripheral circuit.

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