An adaptive discharge anti-sparking lithium battery pack port protection circuit

Abstract

The application discloses a self-adaptive discharge anti-sparking lithium battery pack port protection circuit, and relates to the technical field of lithium battery pack protection plates.The self-adaptive discharge anti-sparking lithium battery pack port protection circuit comprises an automatic detection load circuit, which is used for monitoring control of no-load shutdown and output after load connection; an output starting and output delay circuit, which is used for delay starting discharge output after receiving a load detection or a starting signal of an in-place switch; a discharge current detection circuit, which is used for real-time monitoring of discharge current and intelligent control of working current maintaining and automatic shutdown without current; an output state feedback circuit, which is used for resetting the automatic detection load circuit after output shutdown, so as to enter the next load connection and be normally started again; an in-place switch detection and delay anti-sparking circuit; and an in-place switch function locking circuit.The self-adaptive discharge anti-sparking lithium battery pack port protection circuit can be self-adaptively compatible with two application scenes with or without an in-place switch, can inhibit the sparking phenomenon in the instant of connection from the source, and meets the safety protection requirements of multiple types of lithium battery packs.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery pack protection board technology, specifically relating to an adaptive discharge anti-sparking lithium battery pack port protection circuit. Background Technology

[0002] Currently, lithium battery packs are widely used in electric vehicles, energy storage equipment and other fields. The safety and reliability of their discharge ports directly affect the product's lifespan and safety. The mainstream lithium battery pack protection schemes on the market are divided into two types: constant output type with or without an on-state switch and control type with an on-state switch. Both use protection ICs in conjunction with charge and discharge MOSFETs to achieve basic overcharge, over-discharge, overcurrent and short circuit protection.

[0003] Among them, the non-in-position switch constant output type generally adopts the design of being turned on upon power-up and having the discharge port always energized. The protection IC continuously drives the discharge MOSFET to conduct within the normal battery voltage range, and the discharge port remains in the output state when no load is connected. When the battery pack is connected to a load, the large-capacity capacitor built into the load-side controller will be charged by a sudden large current, forming a spike inrush current far exceeding the terminal's withstand capability. This can easily cause arcing, burning, or even damage to the discharge port. Conventional overcurrent and short-circuit protection can only perform the cut-off action after the abnormality occurs, and cannot suppress the arcing phenomenon at the moment of connection, resulting in a prominent safety hazard.

[0004] Although lithium battery packs with in-position switches can be controlled by an external switch to enable discharge and disconnect the output when no load is applied to reduce the risk of arcing, they require additional detection interfaces and wiring, have poor versatility, and cannot be compatible with battery pack applications without in-position switches; moreover, there is no delay start mechanism when the switch is closed, so there is still the problem of instantaneous capacitor charging arcing.

[0005] Meanwhile, the two protection schemes are independent of each other and cannot adaptively adapt to both application forms with and without an in-position switch, resulting in high product design, production and adaptation costs. The industry lacks an integrated adaptive protection technology that is simple in structure, stable and reliable, and can suppress arcing at the discharge port from the source, making it difficult to meet the safety protection needs of various types of lithium battery packs. Summary of the Invention

[0006] The purpose of this invention is to provide an adaptive discharge anti-sparking lithium battery pack port protection circuit that is adaptively compatible with both application scenarios with and without an in-position switch. It can suppress instantaneous sparking at the source and meet the safety protection requirements of various types of lithium battery packs, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An adaptive discharge anti-sparking lithium battery pack port protection circuit includes: an automatic load detection circuit for monitoring and control that outputs only after no-load shutdown and load connection.

[0009] The output start and hold output delay circuit starts the discharge output after a delay upon receiving the start signal from the load detection or the position switch;

[0010] The discharge current detection circuit is used to monitor the discharge current in real time and perform intelligent control by maintaining the working current and automatically shutting off when there is no current.

[0011] The output status feedback circuit quickly resets the automatic load detection circuit after the output is turned off, so that it can restart normally when the next load is connected.

[0012] In-position switch detection and delayed anti-sparking circuit: In a battery pack with an in-position switch, the switch closing signal is detected, and the output is started after a delay.

[0013] The in-position switch function lockout circuit is used to immediately lock and disable the automatic load detection function when the in-position switch is detected to be connected.

[0014] The output start and hold output delay circuits are electrically connected to the discharge current detection circuit, the automatic load detection circuit, the in-position switch detection and anti-sparking circuit, and the output feedback circuit, respectively. The output terminal of the output feedback circuit and the output terminal of the in-position switch function lock circuit are both connected to the input terminal of the automatic load detection circuit, and the input terminal of the in-position switch function lock circuit is connected to the output terminal of the in-position switch detection and delay anti-sparking circuit.

[0015] When the battery pack is not connected to a load, there is no output at the discharge port. After the load is connected, the battery pack without an on-state switch is detected by the automatic load detection circuit and starts output. The battery pack with an on-state switch is detected by the on-state switch detection and delay anti-arcing circuit and starts output after a delay, so as to suppress the arcing and burning of the discharge port caused by the large current charging of the load capacitor at the moment the load is connected.

[0016] Preferably, in the automatic load detection circuit, the MOSFET Q21 has a resistor R80, a Zener diode ZD1, a capacitor C38, and a resistor R81 connected in parallel at its gate. One end of the resistor R81 is connected to a Zener diode D17, and one end of the Zener diode D17 is connected to a capacitor C37 for connection to the discharge negative terminal. The other end of the capacitor C38, the Zener diode ZD1, and the resistor R80 is grounded.

[0017] Preferably, the output start-up and output delay holding circuit includes a transistor Q20. A resistor R78 and a capacitor C39 are connected in parallel between the emitter and base of the transistor Q20. A diode D16 and a resistor R77 are connected in series with the collector of the transistor Q20. One end of the resistor R77 is connected to a filter circuit, and the other end of the filter circuit is connected to a hold output delay control circuit. The base of the transistor Q20 is connected to a resistor R79, and one end of the resistor R79 is connected to the source (S) terminal of the MOSFET Q21.

[0018] Preferably, the hold output delay control circuit includes MOSFET Q18 and MOSFET Q19. The source (S) terminal of MOSFET Q18 is connected to a resistor R73. One end of the resistor R73 is connected in parallel with a ground capacitor C34 for connection to the battery pack and a ground resistor R74. The gate (G) terminal of MOSFET Q18 is connected to a resistor R71 and a resistor R72 for connection to VCC. One end of the resistor R71 is connected to the source (S) terminal of MOSFET Q19. The filter circuit is connected between the gate (G) terminal and the drain (D) terminal of MOSFET Q19.

[0019] Preferably, the filter circuit includes a resistor R75, a capacitor C45, a Zener diode ZD2, a capacitor C35, and a capacitor C36 connected in parallel between the gate and drain of the MOSFET Q19. A resistor R76 is connected between the capacitor C35 and the negative terminal of the Zener diode ZD2. One end of the resistor R77 is connected to the connection terminal of the capacitors C36 and C35.

[0020] Preferably, the in-situ switch detection and delay anti-arson circuit includes a MOSFET Q17. The drain (D) of the MOSFET Q17 is connected to the junction of resistor R71 and MOSFET Q19. A resistor R70, a Zener diode ZD3, and a capacitor C31 are connected in parallel to the gate (G) of the MOSFET Q17. A resistor R69 is connected between the junction of resistor R70 and Zener diode ZD3. A resistor R66 is connected between the junction of Zener diode ZD3 and resistor R69. One end of resistor R66 is connected to... There is a diode D14, one end of which is connected to a resistor R65 for connection to the output feedback circuit. A transistor Q16 is connected to the connection between the resistor R65 and the diode D14. Resistors R67 and R68 are connected between the base and collector of the transistor Q16. A switch K1 for connection to the output feedback circuit is also connected to the line connecting the transistor Q16 and the resistor R65. The emitter of the transistor Q16 is connected to the connection between the capacitor C31 and the resistor R66.

[0021] Preferably, the discharge current detection circuit includes an operational amplifier U2. A diode D15 and a resistor R82 are connected in series to pin 1 of the operational amplifier U2. A resistor R84 and a resistor R83 are connected in series between pin 2 and pin 1 of the operational amplifier U2. The other end of the resistor R84 is connected to a resistor R85 to ground. A capacitor C33 to ground and a diode D20 for connection to the output feedback circuit are connected to the connection end of the resistors R83 and R84. A resistor R86 is connected between pin 3 and pin 7 of the operational amplifier U2. A resistor R87 and a capacitor C32 are connected in parallel between pin 6 and pin 7 of the operational amplifier U2. A resistor R88 to ground is connected to pin 6 of the operational amplifier U2. A resistor R89 ​​is connected to pin 5 of the operational amplifier U2. A resistor R30 and a resistor R29 connected to the battery pack are connected in parallel to one end of the resistor R89.

[0022] Preferably, the output status feedback circuit includes an optocoupler U4 connected to the negative discharge terminal. The sensing terminal of the optocoupler U4 is connected to a resistor R94. One end of the resistor R94 is connected to a transistor Q23. A resistor R93 and a capacitor C43 are connected in parallel between the base and emitter of the transistor Q23. A Zener diode ZD4 for connection to an automatic load detection circuit is connected to one of the terminals of the resistor R93 and capacitor C43. A resistor R92 is connected to the other terminal of the resistor R93 and capacitor C43. One end is connected to a MOSFET Q22. A resistor R91 is connected between the gate (G) and source (S) of the MOSFET Q22. A resistor R90 is connected to the gate of the MOSFET Q22. One end of the resistor R90 is connected to a transistor Q27. A diode D21 and a resistor R103 are connected in series with the emitter of the transistor Q27. One end of the resistor R103 is connected to one end of the diode D20. A resistor R104 to ground and a resistor R102 connected to the base of the transistor Q26 are connected to the connection point of the resistor R103 and the diode D20.

[0023] Preferably, the in-situ switch function locking circuit includes MOSFETs Q24, Q25, and Q26. The source (S) terminal of MOSFET Q25 is connected to the battery pack. Resistors R101 and R100 are connected in parallel to the gate (G) terminal of MOSFET Q25. One end of resistor R100 is connected to the gate (G) terminal of MOSFET Q26. A diode D18 and a resistor R95 are connected in series to the drain (D) terminal of MOSFET Q26. One end of resistor R95 is connected to the gate (G) terminal of MOSFET Q24. Resistor R99 is connected between the source (S) and gate (G) terminals of MOSFET Q26. Resistor R98 is connected to the gate (G) terminal of MOSFET Q26. One end of resistor R98 is connected to the drain (D) terminal of MOSFET Q24. Resistor R97 is connected between the gate (G) and source (S) terminals of MOSFET Q24. A resistor R96 and a diode D19 are connected in series to the gate (G) terminal of MOSFET Q24.

[0024] Preferably, when there is no in-position switch, the output is started after a delay of 2-3 seconds after the load is connected to suppress instantaneous arcing of the load capacitor. When there is an in-position switch, the output is started after a delay of 2-3 seconds after the switch is closed, and the automatic load detection circuit is locked to disable it.

[0025] The adaptive discharge anti-sparking lithium battery pack port protection circuit proposed in this invention has the following advantages compared with the prior art:

[0026] 1. This invention achieves adaptive compatibility with and without an in-position switch by coordinating an automatic load detection circuit, an output start and hold output delay circuit, a discharge current detection circuit, an output status feedback circuit, an in-position switch detection and delay anti-arcing circuit, and an in-position switch function lockout circuit. When there is no in-position switch, the discharge port has no output if the battery pack is not connected to a load. After the load is connected, the automatic load detection circuit identifies the load connection and starts discharging after an output start delay, suppressing instantaneous arcing caused by constant output under no-load conditions from the source. When there is an in-position switch, the in-position switch detection and delay anti-arcing circuit identifies the switch closing signal and starts output after a delay. At the same time, the in-position switch function lockout circuit automatically disables the automatic load detection circuit to avoid functional conflicts. This eliminates the need for additional detection interfaces and the problem of capacitor charging arcing at the moment of switch closing. It also eliminates the need for post-event cut-off protection by protection ICs, directly controlling the output timing at the load connection or switch closing stage, completely solving the safety hazard of arcing and burning at the discharge port. At the same time, it achieves compatibility of two application scenarios with a single circuit, reducing product design, production and adaptation costs, and meeting the safety protection needs of multiple types of lithium battery packs.

[0027] 2. When the battery pack of this invention is unloaded, the discharge port has no output, avoiding the risk of electric shock and short circuit caused by unloaded charging, and improving the safety of lithium battery pack use;

[0028] 3. This invention can automatically identify whether there is a switch in position. When there is no switch in position, the load detection function will automatically take effect. When there is a switch in position, the load detection function will be automatically locked. There is no need to manually switch modes, which improves adaptability and ease of use. It suppresses the impact of instantaneous high current from the source, avoids the burning and deformation of discharge terminals, and reduces the instantaneous damage of high current to the battery pack, thus extending the overall service life of the lithium battery pack.

[0029] 4. This invention can work in conjunction with conventional lithium battery front-end protection IC modules without affecting basic protection functions such as overcharge, over-discharge, overcurrent, and short circuit. It only adds dedicated anti-sparking protection, resulting in low upgrade costs and a wide range of compatibility. Attached Figure Description

[0030] Figure 1 This is a circuit structure block diagram of the present invention;

[0031] Figure 2 This is a circuit diagram of the present invention;

[0032] Figure 3 This is a block diagram of the connection structure between the present invention and the battery pack. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides, for example Figure 1-3 The adaptive discharge anti-sparking lithium battery pack port protection circuit shown includes an automatic load detection circuit, an output start and hold output delay circuit, a discharge current detection circuit, an output status feedback circuit, an in-situ switch detection and delay anti-sparking circuit, and an in-situ switch function lockout circuit. The output start and hold output delay circuit is electrically connected to the discharge current detection circuit, the automatic load detection circuit, the in-situ switch detection and anti-sparking circuit, and the output feedback circuit, respectively. The output terminal of the output feedback circuit and the output terminal of the in-situ switch function lockout circuit are both connected to the input terminal of the automatic load detection circuit, and the input terminal of the in-situ switch function lockout circuit is connected to the output terminal of the in-situ switch detection and delay anti-sparking circuit.

[0035] When the battery pack is not connected to a load, there is no output at the discharge port. When a load is connected, the battery pack without an in-position switch is detected by the automatic load detection circuit and starts output. After an output start delay, it starts discharging, suppressing the instantaneous arcing caused by constant output under no-load conditions from the source. The battery pack with an in-position switch is detected by the in-position switch detection and delay anti-arc circuit and starts output after a delay, so as to suppress the arcing and burning of the discharge port caused by the large current charging the load capacitor at the moment of load connection. At the same time, the in-position switch function lock circuit automatically disables the automatic load detection circuit to avoid functional conflicts. It does not require an additional detection interface and can eliminate the problem of capacitor charging arcing at the moment of switch closure. It does not rely on the after-the-fact cut-off protection of the protection IC. It directly controls the output timing at the load connection or switch closure stage, completely solving the safety hazard of arcing and burning of the discharge port. At the same time, it achieves compatibility of two types of application scenarios with a single circuit, reduces product design, production and adaptation costs, and meets the safety protection needs of multiple types of lithium battery packs.

[0036] Specifically, the automatic load detection circuit is used for monitoring and control that only outputs data after no-load shutdown and load connection. The automatic load detection circuit uses a MOSFET Q21. The gate (G) of the MOSFET Q21 is connected in parallel with a resistor R80, a Zener diode ZD1, a capacitor C38, and another resistor R81. One end of the resistor R81 is connected to a Zener diode D17, and one end of the Zener diode D17 is connected to a capacitor C37 for connection to the discharge negative terminal. The other ends of the capacitor C38, Zener diode ZD1, and resistor R80 are grounded. The automatic load detection circuit uses an N-MOSFET Q21 as its core, with the gate connected to a resistor... The circuit consists of resistor R80, resistor R81, Zener diode ZD1, and capacitor C38. The discharge negative terminal P- is connected to the circuit through capacitor C37 and Zener diode D17. When no load is connected, N-MOSFET Q21 is cut off, and the circuit has no detection signal. When a load is connected, the discharge positive and negative terminals form a loop through the load. The instantaneous high voltage at the P- terminal drives N-MOSFET Q21 to conduct through the voltage divider formed by capacitor C37, Zener diode D17, resistor R81, and resistor R80, outputting a load connection trigger signal. This accurately identifies the load connection status. There is no signal output when no load is connected, and the start-up process is quickly triggered after the load is connected, providing the basic signal for the delayed output.

[0037] The output start and hold output delay circuit is used to delay the start of the discharge output after receiving a start signal from the load detection or the in-position switch. The output start and hold output delay circuit includes a transistor Q20. A resistor R78 and a capacitor C39 are connected in parallel between the emitter and base of the transistor Q20. A diode D16 and a resistor R77 are connected in series with the collector of the transistor Q20. One end of the resistor R77 is connected to a filter circuit, and the other end of the filter circuit is connected to a hold output delay control circuit. The base of the transistor Q20 is connected to a resistor R79. One end of the resistor R79 is connected to the source (S) terminal of the MOSFET Q21. When the transistor Q21 is turned on, it pulls down the base voltage of the transistor Q20, and the transistor Q20 is turned on. The battery voltage supplies power to the subsequent circuit through the diode D16 and the resistor R77, triggering the hold output delay control circuit to achieve output start and delay hold. It receives and stably transmits the load detection signal, provides drive for the output delay start, and avoids false start caused by signal interference.

[0038] The output delay control circuit includes MOSFETs Q18 and Q19. A resistor R73 is connected to the source (S) terminal of MOSFET Q18. One end of resistor R73 is connected in parallel with a ground capacitor C34 and a ground resistor R74 for connection to the battery pack. A resistor R71 and a resistor R72 for connection to VCC are connected to the gate (G) terminal of MOSFET Q18. One end of resistor R71 is connected to the source (S) terminal of MOSFET Q19. The filter circuit is connected between the gate (G) and drain (D) terminals of MOSFET Q19. When MOSFET Q19 is turned on, it pulls down the gate (G) voltage of MOSFET Q18, turning on MOSFET Q18. The 5V voltage of VCC2 is delivered to the CTLD terminal via MOSFET Q18 and resistor R73, driving the front-end protection IC module to start the discharge output. The filter circuit stores energy, maintaining the conduction of MOSFET Q19 for a long time, achieving output hold, and stably driving the discharge output. The energy storage element achieves long-term output hold, meeting the continuous operation requirements of the load.

[0039] The filtering circuit includes a resistor R75, a capacitor C45, a Zener diode ZD2, a capacitor C35, and a capacitor C36 connected in parallel between the gate (G) and drain (D) terminals of the MOSFET Q19. A resistor R76 is connected between capacitor C35 and the negative terminal of the Zener diode ZD2. One end of a resistor R77 is connected to the junction of capacitors C36 and C35. The battery voltage charges capacitors C35 and C36 via resistor R77, storing electrical energy. After the transistor Q20 is turned off, the capacitors slowly discharge through resistors R76 and R75, maintaining the gate (G) drive voltage of the MOSFET Q19 until the capacitors are depleted, achieving output delay hold. The delay time can reach 42 minutes, ensuring continuous output during normal load operation without repeated triggering.

[0040] The discharge current detection circuit is used to monitor the discharge current in real time and perform intelligent control with a working current hold and automatic shutdown when no current is available. The discharge current detection circuit includes an operational amplifier U2. A diode D15 and a resistor R82 are connected in series to pin 1 of the operational amplifier U2. Resistors R84 and R83 are connected in series between pins 1 and 2 of the operational amplifier U2. The other end of resistor R84 is connected to a ground resistor R85. A ground capacitor C33 and a diode D20 for connection to the output feedback circuit are connected to the junction of resistors R83 and R84. A resistor R86 is connected between pins 3 and 7 of the operational amplifier U2. A resistor R87 and a capacitor C32 are connected in parallel between pins 6 and 7 of the operational amplifier U2. A ground resistor R88 is connected to pin 6 of the operational amplifier U2. Pin 5 of the operational amplifier U2... A resistor R89 ​​is connected to the top. One end of the resistor R89 ​​is connected in parallel with resistors R30 and R29, which are connected to the battery pack. Operational amplifier U2 is composed of U2A and U2B as shown in the figure. U2B collects the voltage drop across the discharge sampling resistors R29 and R30 through resistors R88 and R89. After being amplified 101 times by resistor R87 and capacitor C32, it is sent to the non-inverting input of U2A. The inverting input of U2A is set to a reference voltage of 0.098V by a voltage divider of resistors R83, R84, and R85. When the discharge current is greater than 0.667A, U2A outputs a high level. The MOSFET Q19 is kept on through diode D15 and resistor R82 to maintain the output. When the current is lower than the threshold, U2A outputs a low level and the output is automatically turned off. The discharge current is monitored in real time. The output is maintained when there is a load current and automatically turned off when there is no current, realizing intelligent energy saving and safety protection.

[0041] The output status feedback circuit is used to quickly reset the automatic load detection circuit after the output is turned off, so that it can restart normally when the next load is connected. The output status feedback circuit includes an optocoupler U4 connected to the negative discharge terminal. The sensing terminal of the optocoupler U4 is connected to a resistor R94. One end of the resistor R94 is connected to a transistor Q23. A resistor R93 and a capacitor C43 are connected in parallel between the base and emitter of the transistor Q23. A Zener diode ZD4 for connection to the automatic load detection circuit is connected to one end of the resistor R93 and capacitor C43. A resistor R92 is connected to the other end of the resistor R93 and capacitor C43. One end of the resistor R92 is connected to a MOSFET Q22. A resistor R91 is connected between the gate and source of the MOSFET Q22. A resistor R90 is connected to the gate (G) terminal of the transistor. One end of the resistor R90 is connected to a transistor Q27. The emitter of the transistor Q27 is connected in series with a diode D21 and a resistor R103. One end of the resistor R103 is connected to one end of the diode D20. A ground resistor R104 and a resistor R102 connected to the base of the transistor Q26 are connected to the connection point of the resistor R103 and the diode D20. When the MOSFET Q18 is off, VCC2A becomes low. The voltage stored in the capacitor C44 drives the transistor Q27 to conduct, which in turn triggers the MOSFET Q22 and the transistor Q23 to conduct. The optocoupler U4 works, releasing the charge of the capacitor C37 in the automatic load detection circuit, resetting the transistor Q21. After the output is turned off, the load detection circuit is quickly reset to ensure normal startup when the load is connected next time, improving the stability of the circuit's cyclic operation.

[0042] The in-position switch detection and delay anti-sparking circuit is used in battery packs with an in-position switch to detect a switch closure signal and delay the output. The in-position switch detection and delay anti-sparking circuit includes a MOSFET Q17. The drain (D) of MOSFET Q17 is connected to the junction of resistor R71 and MOSFET Q19. A resistor R70, a Zener diode ZD3, and a capacitor C31 are connected in parallel to the gate (G) of MOSFET Q17. A resistor R69 is connected between the junction of resistor R70 and Zener diode ZD3. A resistor R66 is connected between the junction of Zener diode ZD3 and resistor R69. One end of resistor R66 is connected to diode D14. One end of diode D14 is connected to resistor R65 for connection to the output feedback circuit. Resistor R65 and diode D14... A transistor Q16 is connected to terminal 4. Resistors R67 and R68 are connected between the base and collector of transistor Q16. A switch K1 for connecting to the output feedback circuit is also connected to the line connecting transistor Q16 and resistor R65. The emitter of transistor Q16 is connected to the terminal of capacitor C31 and resistor R66. After the in-position switch K1 is closed, the positive voltage of the battery charges capacitor C31 through diode D14 and resistor R66. After a delay of about 2.59 seconds, MOSFET Q17 turns on, triggering MOSFET Q18 to turn on the output. When the switch is open, transistor Q16 turns on to quickly release the charge of capacitor C31 and immediately turn off the output. This achieves delayed start-up when the in-position switch is closed, suppresses instantaneous arcing of the switch, and quickly turns off the output after the switch is opened, improving the control response speed.

[0043] The in-position switch function lockout circuit is used to immediately lock and disable the automatic load detection function when an in-position switch is detected. The in-position switch function lockout circuit includes MOSFETs Q24, Q25, and Q26. The source (S) terminal of MOSFET Q25 is connected to the battery pack. Resistors R101 and R100 are connected in parallel to the gate (G) terminal of MOSFET Q25. One end of resistor R100 is connected to the gate (G) terminal of MOSFET Q26. A diode D18 and resistor R95 are connected in series to the drain (D) terminal of MOSFET Q26. One end of resistor R95 is connected to the gate (G) terminal of MOSFET Q24. Resistor R99 connects the source (S) and gate (G) terminals of MOSFET Q26. Resistor R98 is connected to the gate (G) terminal of MOSFET Q26. One end of resistor R98 is connected to the drain (D) of MOSFET Q24. Resistor R97 is connected between the gate (G) and source (S) of MOSFET Q24. Resistor R96 and diode D19 are connected in series with the gate (G) of MOSFET Q24. After MOSFET Q17 is turned on, MOSFET Q24 is driven to turn on via diode D19 and resistor R96, which in turn triggers MOSFETs Q26 and Q25 to turn on. MOSFET Q25 pulls down the gate (G) voltage of MOSFET Q19 to permanently turn it off. At the same time, MOSFET Q26 is self-locked via diode D18 and resistor R95 to maintain a locked state, disabling the automatic load detection circuit. When there is an in-position switch, the load detection function is automatically locked to avoid mutual interference between the two types of detection circuits and ensure the stability of the circuit's operating logic.

[0044] In a preferred embodiment, when there is no in-position switch, the output is started after a 2-3 second delay after the load is connected to suppress instantaneous arcing of the load capacitor. When there is an in-position switch, the output is started after a 2-3 second delay after the switch is closed, and the automatic load detection circuit is locked to disable it. By precisely controlling the output delay and reserving a capacitor charging buffer time, instantaneous arcing is completely suppressed, and the adaptive switching logic is clear and reliable.

[0045] This circuit is compatible with series-connected lithium battery packs, such as... Figure 3As shown, the electrical connections between the lithium battery pack and its positive terminal B+, negative terminal B-, charging / discharging positive terminals B+ / P+ / CH+, discharging negative terminal P-, charging negative terminal CH-, and the front-end protection IC module are as follows: Specifically, the battery positive terminal B+ is directly connected to the charging / discharging positive terminals B+ / P+ / CH+, forming a common positive path for charging and discharging the battery pack, providing a common positive terminal for the load power supply and charger input; on the other hand, the battery positive terminal B+ is connected to the in-position switch detection and delay anti-sparking circuit, the in-position switch function lockout circuit, and the output start and hold output delay circuit. This provides the operating power for the above modules and is also connected to the positive power input terminal of the front-end protection IC module to provide the operating voltage for the front-end protection IC module; the negative terminal B- of the battery serves as the common reference ground for the entire protection circuit and the front-end protection IC module, and is connected to the grounding terminals of all components in the automatic load detection circuit, output start and hold output delay circuit, discharge current detection circuit, output status feedback circuit, in-position switch detection and delay anti-arcing circuit, and in-position switch function lockout circuit, respectively. It is also connected to the negative power supply terminal and system ground terminal of the front-end protection IC module to achieve common ground operation;

[0046] The charging / discharging positive terminals B+ / P+ / CH+ are directly shorted to the battery positive terminal B+, serving as the main positive interface for external charging and discharging of the battery pack. This port is only used for power transmission and is not connected to the detection and control branch of this anti-sparking circuit. The discharging negative terminal P- serves as the core detection and power output port of this circuit. One end is connected to the negative terminal of the load, and the other end is divided into two branches: one is connected to the capacitor C37 of the automatic load detection circuit to realize the load connection status detection; the other branch passes through the sampling resistor R29 and resistor R30 of the discharge current detection circuit and is connected to the corresponding discharge negative terminal sampling terminal of the front-end protection IC module, and is connected in series with the discharge MOS switch controlled by the front-end protection IC module. The other end of the discharge MOS switch is connected to the battery negative terminal B-, forming a complete discharge power loop. The charging negative terminal CH- is independently connected to the charging control terminal and the charging MOS switch of the front-end protection IC module. No component in this adaptive discharge anti-sparking circuit is directly connected to the charging negative terminal CH-. The charging loop and charging control logic are completely implemented independently by the front-end protection IC module. This circuit does not participate in or interfere with the charging process.

[0047] This circuit works in conjunction with the front-end protection IC module through control signals and power circuits: the CTLD pin of the output start and hold output delay circuit in this circuit is directly connected to the discharge enable control pin of the front-end protection IC module, used to output a discharge allow or disable signal to the front-end protection IC module. When CTLD is high, the front-end protection IC module can normally drive the discharge MOS switch to conduct; when CTLD is low, the front-end protection IC module forcibly shuts down the discharge MOS switch. The discharge drive pin of the front-end protection IC module is directly connected to the gate of the discharge MOS switch to implement basic protection functions such as overcharge, over-discharge, overcurrent, and short circuit. The VCC2 and VCC2A pins of this circuit provide auxiliary power to the front-end protection IC module to ensure stable operation. One end of the in-position switch is connected to the positive terminal B+ of the battery, and the other end is connected to the signal input terminal of the in-position switch detection and delay anti-arson circuit of this circuit, used to provide the in-position switch on / off detection signal to this circuit, realizing delayed start and function lock in in-position switch application scenarios.

[0048] In practical operation, for lithium battery packs without a presence switch, after the positive and negative terminals of charging / discharging are connected to the load, the automatic load detection circuit triggers the output start-up delay circuit. After a delay of 2-3 seconds, the CTLD terminal outputs a high level, and the front-end protection IC module drives the discharge MOS switch to conduct, allowing the discharge port to output normally. When the discharge current is greater than 0.667A, the discharge current detection circuit maintains the output. After the load is disconnected, the output turns off, and the output status feedback circuit resets the detection circuit. For lithium battery packs with a presence switch, after the switch is closed, the presence switch detection circuit starts outputting after a delay of 2.59 seconds. At the same time, the function lockout circuit disables the automatic load detection circuit to avoid circuit conflicts. During charging, the charger is connected to the positive and negative terminals of charging / discharging, and the front-end protection IC module independently controls the charging MOS switch. This circuit does not affect the charging process. This implementation method has a simple circuit structure, clear component connections, stable and reliable operation, and can effectively solve the problem of arcing and burning at the discharge port of lithium battery packs. It is adaptively compatible with scenarios with and without a presence switch, fully meeting the safety protection requirements of lithium battery packs.

[0049] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adaptive discharge spark-proof lithium battery pack port protection circuit, characterized in that: include: Automatic load detection circuit, used for monitoring and control that outputs only after no-load shutdown and load connection; The output start and hold output delay circuit starts the discharge output after a delay upon receiving the start signal from the load detection or the position switch; The discharge current detection circuit is used to monitor the discharge current in real time and perform intelligent control by maintaining the working current and automatically shutting off when there is no current. The output status feedback circuit quickly resets the automatic load detection circuit after the output is turned off, so that it can restart normally when the next load is connected. In-position switch detection and delayed anti-sparking circuit: In a battery pack with an in-position switch, the switch closing signal is detected, and the output is started after a delay. The in-position switch function lockout circuit is used to immediately lock and disable the automatic load detection function when the in-position switch is detected to be connected. The output start and hold output delay circuits are electrically connected to the discharge current detection circuit, the automatic load detection circuit, the in-position switch detection and anti-sparking circuit, and the output feedback circuit, respectively. The output terminal of the output feedback circuit and the output terminal of the in-position switch function lock circuit are both connected to the input terminal of the automatic load detection circuit, and the input terminal of the in-position switch function lock circuit is connected to the output terminal of the in-position switch detection and delay anti-sparking circuit. When the battery pack is not connected to a load, there is no output at the discharge port. After the load is connected, the battery pack without an on-state switch is detected by the automatic load detection circuit and starts output. The battery pack with an on-state switch is detected by the on-state switch detection and delay anti-arcing circuit and starts output after a delay, so as to suppress the arcing and burning of the discharge port caused by the large current charging of the load capacitor at the moment the load is connected.

2. The self-adapting discharge anti-sparking lithium battery pack port protection circuit according to claim 1, characterized in that: The automatic load detection circuit uses a MOSFET Q21. The gate of the MOSFET Q21 is connected in parallel with a resistor R80, a Zener diode ZD1, a capacitor C38, and a resistor R81. One end of the resistor R81 is connected to a Zener diode D17. One end of the Zener diode D17 is connected to a capacitor C37 for connection to the discharge negative terminal. The other end of the capacitor C38, the Zener diode ZD1, and the resistor R80 is grounded.

3. The self-adapting discharge anti-sparking lithium battery pack port protection circuit according to claim 2, characterized in that: The output start-up and hold output delay circuit includes a transistor Q20. A resistor R78 and a capacitor C39 are connected in parallel between the emitter and base of the transistor Q20. A diode D16 and a resistor R77 are connected in series with the collector of the transistor Q20. One end of the resistor R77 is connected to a filter circuit, and the other end of the filter circuit is connected to a hold output delay control circuit. The base of the transistor Q20 is connected to a resistor R79, and one end of the resistor R79 is connected to the source (S) terminal of the MOSFET Q21.

4. The self-adapting discharge anti-sparking lithium battery pack port protection circuit according to claim 3, characterized in that: The output delay control circuit includes MOSFETs Q18 and Q19. The source (S) terminal of MOSFET Q18 is connected to a resistor R73. One end of the resistor R73 is connected in parallel with a ground capacitor C34 for connection to the battery pack and a ground resistor R74. The gate (G) terminal of MOSFET Q18 is connected to a resistor R71 and a resistor R72 for connection to VCC. One end of the resistor R71 is connected to the source (S) terminal of MOSFET Q19. The filter circuit is connected between the gate (G) and drain (D) terminals of MOSFET Q19.

5. The self-adapting discharge anti-sparking lithium battery pack port protection circuit according to claim 4, characterized in that: The filter circuit includes a resistor R75, a capacitor C45, a Zener diode ZD2, a capacitor C35, and a capacitor C36 connected in parallel between the gate and drain of the MOSFET Q19. A resistor R76 is connected between the capacitor C35 and the negative terminal of the Zener diode ZD2. One end of the resistor R77 is connected to the connection terminal of the capacitors C36 and C35.

6. The self-adapting discharge anti-sparking lithium battery pack port protection circuit according to claim 4, characterized in that: The in-situ switch detection and time-delay anti-arson circuit includes a MOSFET Q17. The drain (D) of MOSFET Q17 is connected to the junction of resistor R71 and MOSFET Q19. A resistor R70, a Zener diode ZD3, and a capacitor C31 are connected in parallel to the gate (G) of MOSFET Q17. A resistor R69 is connected between the junction of resistor R70 and Zener diode ZD3. A resistor R66 is connected between the junction of Zener diode ZD3 and resistor R69. One end of resistor R66 is connected to two... A diode D14 is connected to a resistor R65 for connection to an output feedback circuit. A transistor Q16 is connected to the connection point of the resistor R65 and the diode D14. Resistors R67 and R68 are connected between the base and collector of the transistor Q16. A switch K1 for connection to the output feedback circuit is also connected to the line connecting the transistor Q16 and the resistor R65. The emitter of the transistor Q16 is connected to the connection point of the capacitor C31 and the resistor R66.

7. The self-adapting discharge anti-sparking lithium battery pack port protection circuit of claim 1, wherein: The discharge current detection circuit includes an operational amplifier U2. A diode D15 and a resistor R82 are connected in series to pin 1 of the operational amplifier U2. A resistor R84 and a resistor R83 are connected in series between pin 2 and pin 1 of the operational amplifier U2. The other end of the resistor R84 is connected to a resistor R85 to ground. A capacitor C33 to ground and a diode D20 for connection to the output feedback circuit are connected to the connection end of the resistors R83 and R84. A resistor R86 is connected between pin 3 and pin 7 of the operational amplifier U2. A resistor R87 and a capacitor C32 are connected in parallel between pin 6 and pin 7 of the operational amplifier U2. A resistor R88 to ground is connected to pin 6 of the operational amplifier U2. A resistor R89 ​​is connected to pin 5 of the operational amplifier U2. A resistor R30 and a resistor R29 connected to the battery pack are connected in parallel to one end of the resistor R89.

8. The adaptive discharge anti-sparking lithium battery pack port protection circuit according to claim 1, characterized in that: The output status feedback circuit includes an optocoupler U4 connected to the negative discharge terminal. A resistor R94 is connected to the sensing terminal of the optocoupler U4. One end of the resistor R94 is connected to a transistor Q23. A resistor R93 and a capacitor C43 are connected in parallel between the base and emitter of the transistor Q23. A Zener diode ZD4 for connection to an automatic load detection circuit is connected to one of the terminals of the resistor R93 and capacitor C43. A resistor R92 is connected to the other terminal of the resistor R93 and capacitor C43. One end of the resistor R92... A MOSFET Q22 is connected. A resistor R91 is connected between the gate (G) and source (S) of the MOSFET Q22. A resistor R90 is connected to the gate of the MOSFET Q22. One end of the resistor R90 is connected to a transistor Q27. A diode D21 and a resistor R103 are connected in series at the emitter of the transistor Q27. One end of the resistor R103 is connected to one end of the diode D20. A resistor R104 to ground and a resistor R102 connected to the base of the transistor Q26 are connected to the junction of the resistor R103 and the diode D20.

9. The self-adapting discharge anti-sparking lithium battery pack port protection circuit of claim 1, wherein: The in-situ switch function locking circuit includes MOSFETs Q24, Q25, and Q26. The source (S) of MOSFET Q25 is connected to the battery pack. Resistors R101 and R100 are connected in parallel to the gate (G) of MOSFET Q25. One end of resistor R100 is connected to the gate (G) of MOSFET Q26. Diode D18 and resistor R95 are connected in series to the drain (D) of MOSFET Q26. One end of resistor R95 is connected to the gate (G) of MOSFET Q24. Resistor R99 connects the source (S) and gate (G) of MOSFET Q26. Resistor R98 is connected to the gate (G) of MOSFET Q26. One end of resistor R98 is connected to the drain (D) of MOSFET Q24. Resistor R97 connects the gate (G) and source (S) of MOSFET Q24. Resistor R96 and diode D19 are connected in series to the gate (G) of MOSFET Q24.

10. The self-adapting discharge anti-sparking lithium battery pack port protection circuit of claim 1, wherein: When there is no in-position switch, the output starts after a 2-3 second delay after the load is connected to suppress instantaneous arcing of the load capacitor. When there is an in-position switch, the output starts after a 2-3 second delay after the switch is closed, and the automatic load detection circuit is locked to disable it.

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