Short-circuit protection circuit and method and battery management system

Abstract

The invention discloses a short-circuit protection circuit and method and a battery management system, and relates to the technical field of circuit protection. The short-circuit protection circuit comprises a current detection circuit, a protection circuit and a control circuit. Wherein the current detection circuit detects the charging current / discharging current of the battery and outputs a corresponding current detection signal. The protection circuit controls the charging and discharging circuit to be switched off when detecting that the loop between the charging and discharging circuit and the battery is short-circuited according to the current detection signal, and controls the charging and discharging circuit to be switched on when detecting that the loop between the charging and discharging circuit and the battery is normal. And the control circuit controls the charging and discharging circuit to be kept switched off when determining that a loop between the charging and discharging circuit and the battery is short-circuited and effective according to the current detection signal. Therefore, the circuit can be immediately turned off to perform short-circuit protection when overcurrent occurs in the circuit, and the circuit is maintained to be turned off to perform short-circuit protection when an overcurrent event is determined to be effective.

Description

Technical Field

[0001] This application relates to the technical field of circuit protection, and particularly to a short - circuit protection circuit, method, and battery management system. Background Art

[0002] In the backup power supply system of communication base stations, lithium batteries, as a new, clean, and renewable secondary energy source, play a crucial role. To ensure the safety of the battery and extend its service life, the battery management system (BMS) must have intelligent management and protection functions, especially for short - circuit protection. When a short - circuit occurs, the current may instantaneously reach several thousand amperes. If the BMS cannot cut off the current in a timely and effective manner, it may lead to cell damage, BMS failure, and even dangerous safety hazards. Therefore, the speed and accuracy of the short - circuit protection function are crucial for ensuring the normal operation of the system and personnel safety.

[0003] In one protection scheme, the BMS amplifies the short - circuit signal through an operational amplifier chip, and then the MCU makes a judgment and controls the protection. However, the MCU may be performing other tasks and cannot respond to the short - circuit signal within 50 microseconds, resulting in a rapid increase in the short - circuit current, damaging the MOS transistor and the battery. In another scheme, the priority of the short - circuit interrupt function is set to the highest and the delay processing is removed, but this method is easily interfered by slight fluctuations, resulting in false short - circuit alarms and affecting the normal charging and discharging of the battery.

[0004] The above content is only used to assist in understanding the technical solution of this application, and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of this application is to provide a short - circuit protection circuit, aiming to solve the problems of slow response speed or easy generation of short - circuit false alarms in existing short - circuit protection schemes.

[0006] To achieve the above purpose, the short - circuit protection circuit proposed in this application is applied to a battery management system, and the battery management system includes a charge - discharge circuit for controlling the charging / discharging of the battery; the short - circuit protection circuit includes:

[0007] A current detection circuit, the detection end of the current detection circuit is connected to one end of the battery, and the current detection circuit is used to detect the charging current / discharging current of the battery and output a corresponding current detection signal;

[0008] A protection circuit, the control end of the protection circuit is connected to the first controlled end of the charge and discharge circuit, and the signal input end of the protection circuit is connected to the first output end of the current detection circuit; the protection circuit is used to control the charge and discharge circuit to turn off when it detects a short circuit in the loop between the charge and discharge circuit and the battery according to the current detection signal, and control the charge and discharge circuit to turn on when it detects that the loop between the charge and discharge circuit and the battery is normal;

[0009] A control circuit, the signal input end of the control circuit is connected to the second output end of the current detection circuit, and the first control end of the control circuit is connected to the second controlled end of the charge and discharge circuit; the control circuit is used to control the charge and discharge circuit to remain off when it determines that the loop between the charge and discharge circuit and the battery is short-circuited and valid according to the current detection signal.

[0010] In one embodiment, the protection circuit is specifically used for:

[0011] When it is determined according to the current detection signal that the current in the loop between the charge and discharge circuit and the battery is greater than a first preset threshold, controlling the charge and discharge circuit to turn off; and when the current detection signal determines that the current in the loop between the charge and discharge circuit and the battery is less than a second preset threshold, controlling the charge and discharge circuit to turn on; the first preset threshold is greater than the second preset threshold.

[0012] In one embodiment, the control circuit is specifically used for:

[0013] When the number of times that the voltage value of the current detection signal exceeds a third preset threshold within a preset time period is detected to reach a preset number of times, it is determined that the on / off frequency of the charge and discharge circuit reaches a preset frequency, and the charge and discharge circuit is controlled to remain off.

[0014] In one embodiment, the protection circuit includes a relay and a first switching tube; the first end of the first switching tube is connected to the negative electrode of the battery, the second end of the first switching tube is connected to the first contact of the relay, the controlled end of the first switching tube is connected to the signal input end of the protection circuit, and the second contact of the relay is connected to the drive signal end of the charge and discharge circuit.

[0015] In one embodiment, the short-circuit protection circuit further includes:

[0016] An enable circuit, the signal input end of the enable circuit is connected to the second control end of the control circuit, and the enable end of the enable circuit is connected to the controlled end of the protection circuit; the enable circuit is used to control the protection circuit to work / stop working according to the enable signal output by the control circuit.

[0017] In one embodiment, the enabling circuit includes a second switching transistor, a first voltage stabilizing diode, a first diode, and a second diode;

[0018] The controlled terminal of the second switching transistor is connected to the signal input terminal of the enabling circuit. The first terminal of the second switching transistor and the positive electrode of the first voltage stabilizing diode are grounded. The second terminal of the second switching transistor, the negative electrode of the first voltage stabilizing diode, the positive electrode of the first diode are connected to the first enabling terminal of the protection circuit. The negative electrode of the first diode and the negative electrode of the second diode are connected to the second enabling terminal of the protection circuit. The positive electrode of the second diode is connected to the power supply terminal of the enabling circuit.

[0019] In one embodiment, the short - circuit protection circuit further includes:

[0020] A signal amplification circuit, the input terminal of the signal amplification circuit is connected to the signal output terminal of the current detection circuit. The first output terminal of the signal amplification circuit is connected to the signal input terminal of the protection circuit. The second output terminal of the signal amplification circuit is connected to the signal input terminal of the control circuit. The signal amplification circuit is used to amplify the current detection signal and then output it.

[0021] The present application also proposes a short - circuit protection method applied to a battery management system. The battery management system includes a charge - discharge circuit for controlling the charging / discharging of a battery. The short - circuit protection method includes:

[0022] Detect the charging current / discharging current of the battery and output a corresponding current detection signal;

[0023] When it is detected according to the current detection signal that there is a short - circuit in the loop between the charge - discharge circuit and the battery, control the charge - discharge circuit to turn off. When it is detected that the loop between the charge - discharge circuit and the battery is normal, control the charge - discharge circuit to turn on;

[0024] When it is determined according to the current detection signal that there is a short - circuit in the loop between the charge - discharge circuit and the battery and it is effective, control the charge - discharge circuit to remain off.

[0025] In one embodiment, the step of when it is detected according to the current detection signal that there is a short - circuit in the loop between the charge - discharge circuit and the battery, control the charge - discharge circuit to turn off. When it is detected that the loop between the charge - discharge circuit and the battery is normal, control the charge - discharge circuit to turn on includes:

[0026] When it is determined according to the current detection signal that the current in the loop between the charge and discharge circuit and the battery is greater than a first preset threshold, control the charge and discharge circuit to turn off; and when it is determined according to the current detection signal that the current in the loop between the charge and discharge circuit and the battery is less than a second preset threshold, control the charge and discharge circuit to turn on; the first preset threshold is greater than the second preset threshold.

[0027] In one embodiment, the step of controlling the charge and discharge circuit to remain off when it is determined according to the current detection signal that the loop between the charge and discharge circuit and the battery is short-circuited and valid includes:

[0028] When the number of times that the voltage value of the current detection signal exceeds a third preset threshold within a preset time period is detected to reach a preset number of times, it is determined that the on / off frequency of the charge and discharge circuit reaches a preset frequency, and the charge and discharge circuit is controlled to remain off.

[0029] The present application also provides a battery management system, which includes a charge and discharge circuit for controlling the charging / discharging of the battery and the short-circuit protection circuit as described above.

[0030] The technical solution of the present application adopts a short-circuit protection circuit, which is applied to a battery management system. The battery management system includes a charge and discharge circuit for controlling the charging / discharging of the battery. The short-circuit protection circuit includes a current detection circuit, a protection circuit and a control circuit. Among them, the current detection circuit detects the charging current / discharging current of the battery and outputs a corresponding current detection signal. When the protection circuit detects a short circuit in the loop between the charge and discharge circuit and the battery according to the current detection signal, it controls the charge and discharge circuit to turn off, and when it detects that the loop between the charge and discharge circuit and the battery is normal, it controls the charge and discharge circuit to turn on. When the control circuit determines according to the current detection signal that the loop between the charge and discharge circuit and the battery is short-circuited and valid, it controls the charge and discharge circuit to remain off. Compared with the prior art, when the protection circuit detects a short circuit in the loop between the charge and discharge circuit and the battery, it quickly controls the charge and discharge circuit to turn off, realizing an immediate response to short-circuit protection. When the protection circuit detects that the loop between the charge and discharge circuit and the battery is normal, it quickly controls the charge and discharge circuit to turn on, avoiding false short-circuit events caused by interference, and the battery can resume normal charging and discharging in time. When the control circuit determines according to the current detection signal that the loop between the charge and discharge circuit and the battery is short-circuited and valid, at this time, the possibility of false short-circuit events is excluded, and the charge and discharge circuit is officially controlled to remain off. In this way, the present application can simultaneously achieve fast response and avoid false triggering of short circuits, and can provide safe and reliable short-circuit protection measures. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0032] Figure 1 Schematic structural diagram of an embodiment of the short - circuit protection circuit provided by the present application;

[0033] Figure 2 Schematic structural diagram of another embodiment of the short - circuit protection circuit provided by the present application;

[0034] Figure 3 Electronic circuit diagram of the protection circuit and the enable circuit of an embodiment of the short - circuit protection circuit provided by the present application;

[0035] Figure 4 Electronic circuit diagram of the signal amplification circuit of an embodiment of the short - circuit protection circuit provided by the present application;

[0036] Figure 5 Electronic circuit diagram of the current detection circuit of an embodiment of the short - circuit protection circuit provided by the present application;

[0037] Figure 6 Schematic flowchart of an embodiment of the short - circuit protection method provided by the present application.

[0038] Description of the reference numerals in the drawings:

[0039]

[0040] The realization of the purpose of the present application, functional features and advantages will be further described in conjunction with the embodiments and with reference to the drawings. Detailed implementation manners

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0042] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0043] In addition, the descriptions involving "first", "second", etc. in this application are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0044] As an important part of the backup power supply for communication base stations, the safety and reliability of lithium batteries are crucial. The battery management system (BMS) plays the role of a "battery nanny" or "battery steward", preventing problems such as overcharging, over-discharging, and short circuits of the battery by intelligently managing and maintaining each battery cell, thereby extending the service life of the battery. Especially for the 48V / 100AH specification batteries used in communication base stations, the current may soar to 2000 amperes instantaneously in case of a short circuit. Therefore, the BMS must have a rapid and reliable short-circuit protection function to ensure the normal operation of the system and the safety of operators.

[0045] The common BMS short-circuit protection scheme on the market currently is: when a short circuit occurs, the current flows through a shunt resistor to generate a differential pressure signal, which is amplified by an operational amplifier and then connected to the MCU (microcontroller unit). If a voltage of 3.3V is detected, it indicates that a short circuit has occurred. The MCU enters the corresponding interrupt function and issues an instruction to control the MOS tube to close after software delay filtering to confirm that the short-circuit state still exists, achieving the protection effect. However, this method has significant drawbacks. When the MCU is handling other important tasks, it may not be able to respond to the short-circuit event in time, resulting in exceeding the 50-microsecond safety time limit, causing damage to the MOS tube and even affecting the battery safety.

[0046] To solve the above problems, another strategy is to set the priority of the short-circuit interrupt to the highest and immediately respond to the short-circuit signal without any delay or filtering. Once a valid short-circuit signal is detected, an instruction is immediately sent to close the MOS tube and report the short-circuit event. Although this method can respond to short circuits more quickly, it is also prone to false alarms of short circuits due to minor interference, bringing inconvenience to the normal use of users. In an existing short-circuit protection scheme, the BMS amplifies the short-circuit signal through an operational amplifier chip, and then the MCU makes a judgment and controls the protection. However, the MCU may be performing other tasks and cannot respond to the short-circuit signal within 50 microseconds, resulting in a rapid increase in the short-circuit current, damaging the MOS tube and the battery.

[0047] This application proposes a short-circuit protection circuit.

[0048] Please refer to Figure 1 , in an embodiment of the present application, the short - circuit protection circuit includes:

[0049] A current detection circuit 01, the detection end of the current detection circuit 01 is connected to one end of the battery. The current detection circuit 01 is used to detect the charging current / discharging current of the battery and output a corresponding current detection signal;

[0050] A protection circuit 02, the control end of the protection circuit 02 is connected to the first controlled end of the charge - discharge circuit 06, and the signal input end of the protection circuit 02 is connected to the first output end of the current detection circuit 01. The protection circuit 02 is used to control the charge - discharge circuit 06 to turn off when it detects a loop short - circuit between the charge - discharge circuit 06 and the battery according to the current detection signal, and control the charge - discharge circuit 06 to turn on when it detects that the loop between the charge - discharge circuit 06 and the battery is normal;

[0051] A control circuit 03, the signal input end of the control circuit 03 is connected to the second output end of the current detection circuit 01, and the first control end of the control circuit 03 is connected to the second controlled end of the charge - discharge circuit 06. The control circuit 03 is used to control the charge - discharge circuit 06 to maintain the off state when it determines that the loop between the charge - discharge circuit 06 and the battery is short - circuited and effective according to the current detection signal.

[0052] It should be noted that the current detection circuit 01 may include a shunt resistor and an operational amplifier. The shunt resistor is used to detect the charging or discharging current flowing through the battery. When current passes through, a voltage difference is generated across the shunt resistor. The operational amplifier can amplify the tiny voltage difference on the shunt resistor to a level suitable for processing by the control circuit 03.

[0053] The protection circuit 02 may include a switching transistor and a relay K. The switching transistor can quickly respond when detecting an abnormal current (such as a large current in a short - circuit situation), control the action of the relay K, so as to pull down the drive signal for driving the charge - discharge circuit 06, and then turn off the loop between the charge - discharge circuit 06 and the battery, thereby realizing the protection of the battery.

[0054] The control circuit 03 may include an MCU (Microcontroller Unit), which is used to receive and analyze the current detection signal, execute corresponding algorithmic logic to judge whether the loop is normal, and trigger the protection action only when the short - circuit is effective, and control the charge - discharge circuit 06 to maintain the off state.

[0055] It should be noted that the charge and discharge circuit 06 may include a MOS transistor drive circuit and a MOS transistor charge and discharge circuit. When the BMS operates normally, the control circuit 03 issues an instruction to the MOS transistor drive circuit, causing the charge and discharge MOS transistors of the MOS transistor charge and discharge circuit to close normally, and the BMS can perform normal charge and discharge operations. When a short circuit occurs, the short-circuit current flows through the current detection circuit 01. The current detection circuit 01 samples the current and outputs a corresponding current detection signal to the protection circuit 02 and the control circuit 03. If this current detection signal meets the action threshold condition of the protection circuit 02, the protection circuit 02 will first control the MOS transistor charge and discharge circuit to turn off. After the disconnection, the current becomes 0, so the short-circuit current and the current detection signal become 0, and the protection circuit 02 will control the MOS transistor charge and discharge circuit to return to the normal state. At this time, there is again a short-circuit current flowing through, and it will again pass through the current detection circuit 01, generating a current detection signal to control the actions of the protection circuit 02 and the MOS transistor charge and discharge circuit. According to the above principle, the current detection signal will be emitted in a pulsed manner, and the MOS transistor charge and discharge circuit will continuously repeat turning on and off. At this time, the MOS transistors of the MOS transistor charge and discharge circuit operate in the linear region and have a relatively large internal resistance, suppressing the increase in current. Therefore, even in a short-circuit state, the current is very small and will not damage the MOS transistors. At the same time, after receiving this current detection signal, the control circuit 03 filters out interference signals through a specific filtering algorithm to determine whether this signal is a real and effective short-circuit signal. If it is a real and effective short-circuit signal, the control circuit 03 issues an instruction to the MOS transistor drive circuit to turn off the MOS transistor charge and discharge circuit. In this way, the short-circuit protection is successfully executed. Among them, the protection circuit 02 plays a key role, that is, as long as an effective short-circuit signal is given to the protection circuit 02, it will immediately give priority to controlling the MOS transistor charge and discharge circuit to turn off until the control circuit 03 determines that this short-circuit signal is effective, and then it issues an instruction to the MOS transistor drive circuit to officially turn off the MOS transistor charge and discharge circuit, finally realizing the normal execution of the short-circuit protection function.

[0056] In this application, the current detection circuit 01 detects the charging current / discharging current of the battery and outputs a corresponding current detection signal. When the protection circuit 02 detects a short circuit in the loop between the charge-discharge circuit 06 and the battery based on the current detection signal, it controls the charge-discharge circuit 06 to turn off. When it detects that the loop between the charge-discharge circuit 06 and the battery is normal, it controls the charge-discharge circuit 06 to turn on. When the control circuit 03 determines that the loop between the charge-discharge circuit 06 and the battery is short-circuited and valid based on the current detection signal, it controls the charge-discharge circuit 06 to remain off. Compared with the prior art, when the protection circuit 02 detects a short circuit in the loop between the charge-discharge circuit 06 and the battery, it quickly controls the charge-discharge circuit 06 to turn off, achieving an immediate response to short-circuit protection. When the protection circuit 02 detects that the loop between the charge-discharge circuit 06 and the battery is normal, it quickly controls the charge-discharge circuit 06 to turn on, avoiding false short-circuit events caused by interference, and the battery can resume normal charging and discharging in a timely manner. When the control circuit 03 determines that the loop between the charge-discharge circuit 06 and the battery is short-circuited and valid based on the current detection signal, the possibility of false short-circuit events is excluded at this time, and the charge-discharge circuit 06 is officially controlled to remain off. In this way, this application can achieve both fast response and avoid false triggering of short circuits, and can provide a safe and reliable short-circuit protection measure.

[0057] In an embodiment of this application, the protection circuit 02 is specifically configured to:

[0058] When it is determined based on the current detection signal that the current in the loop between the charge-discharge circuit 06 and the battery is greater than a first preset threshold, control the charge-discharge circuit 06 to turn off; and when the current detection signal determines that the current in the loop between the charge-discharge circuit 06 and the battery is less than a second preset threshold, control the charge-discharge circuit 06 to turn on; the first preset threshold is greater than the second preset threshold.

[0059] The control circuit 03 is specifically configured to:

[0060] When the number of times the voltage value of the current detection signal exceeds a third preset threshold within a preset time period is detected to reach a preset number of times, it is determined that the on / off frequency of the charge-discharge circuit 06 reaches a preset frequency, and the charge-discharge circuit 06 is controlled to remain off.

[0061] In this embodiment, when the current detection signal indicates that the loop current value exceeds the first preset threshold (indicating an overcurrent phenomenon), the protection circuit 02 will immediately respond and control the charge and discharge circuit 06 to turn off. At this time, since the circuit is cut off, the loop current value measured by the current detection signal will quickly drop to zero. After the protection circuit 02 controls the charge and discharge circuit 06 to turn off, the current quickly drops until it is lower than the second preset threshold, then the protection circuit 02 controls the charge and discharge circuit 06 to turn on again and resume normal operation. Based on this, when an overcurrent phenomenon occurs, a pulsed waveform loop current will be generated between the charge and discharge circuit 06 and the battery, and the current detection circuit 01 also outputs a corresponding pulsed waveform current detection signal.

[0062] It should be noted that the phenomenon that the voltage value of each current detection signal exceeds the third preset threshold can be defined as a "short - circuit pulse". Under a "short - circuit pulse", the charge and discharge circuit 06 has a turn - off action, and the loop current value quickly drops to zero until it is lower than the second preset threshold, and the charge and discharge circuit 06 has a turn - on action. If the short - circuit event is a false - alarm short - circuit event such as circuit interference, the overcurrent time will not exceed the preset time period, and the on / off frequency of the charge and discharge circuit 06 caused within the preset time period is less and does not reach the preset frequency. If the short - circuit event is a valid short - circuit event and the overcurrent time is long, exceeding the preset time period, the on / off frequency of the charge and discharge circuit 06 caused within the preset time period is more and reaches the preset frequency. Thus, the control circuit 03 can determine whether the short - circuit event is valid by continuously monitoring the current detection signal. For example, within a set time period (such as 3 seconds), if the number of "short - circuit pulses" detected within the preset time period reaches the preset number (such as 40), the control circuit 03 determines that the current short - circuit event is valid. At this time, it controls the charge and discharge circuit 06 to remain off to prevent overcurrent from damaging the battery and other circuits of the battery management system.

[0063] Please refer to Figure 3 , in an embodiment of the present application, the protection circuit 02 includes a relay K and a first switching tube Q1; the first end of the first switching tube Q1 is connected to the negative electrode of the battery, the second end of the first switching tube Q1 is connected to the first contact (contact 3) of the relay K, the controlled end of the first switching tube Q1 is connected to the signal input end of the protection circuit 02, and the second contact (contact 4) of the relay K is connected to the drive signal end (DSG end) of the charge and discharge circuit 06.

[0064] It should be noted that the protection circuit 02 may further include a first resistor R1, a second resistor R2, a fourth resistor R4, and a light-emitting diode DL. One end of the first resistor R1 is connected to the signal input terminal of the protection circuit 02, and the other end of the first resistor R1, one end of the second resistor R2 are connected to the controlled terminal of the first switching transistor Q1. The other end of the second resistor R2, one end of the third resistor R3 are connected to the first end of the first switching transistor Q1. The other end of the third resistor R3, the second end of the first switching transistor Q1 are connected to the first contact (contact 3) of the relay K. One end of the fourth resistor R4 is connected to the contact 1 of the relay K, the other end of the fourth resistor R4 is connected to the positive electrode of the light-emitting diode DL, and the negative electrode of the light-emitting diode DL is connected to the contact 8 of the relay K. In this embodiment, the first switching transistor Q1 may be an NMOS transistor.

[0065] It should be noted that when the protection circuit 02 is operating, the contact 3 of the relay K is conductively connected to the contact 4 of the relay K. If the voltage value of the input current detection signal is greater than the first preset threshold, the first switching transistor Q1 is turned on, and the protection circuit 02 pulls the drive signal DSG of the charge and discharge circuit 06 to the BAT- voltage to control the MOS transistor of the charge and discharge circuit 06 to turn off. If the voltage value of the input current detection signal is less than the second preset threshold, the first switching transistor Q1 is turned off, and the drive signal of the charge and discharge circuit 06 is in a normal state. At this time, the battery can be normally charged and discharged.

[0066] Please refer to Figure 2 , in an embodiment of the present application, the short-circuit protection circuit further includes:

[0067] An enable circuit 04, the signal input terminal of the enable circuit 04 is connected to the second control terminal of the control circuit 03, and the enable terminal of the enable circuit 04 is connected to the controlled terminal of the protection circuit 02; the enable circuit 04 is used to control the operation / stop operation of the protection circuit 02 according to the enable signal output by the control circuit 03.

[0068] In this embodiment, during maintenance or troubleshooting, the protection circuit 02 can be deactivated by sending an instruction through the control circuit 03, which helps technicians to more easily identify the problem without being interfered by the protection mechanism.

[0069] Please refer to Figure 3 , in an embodiment of the present application, the enable circuit 04 includes a second switching transistor Q2, a first voltage regulator diode DW1, a first diode D1, and a second diode D2;

[0070] The controlled terminal of the second switching transistor Q2 is connected to the signal input terminal of the enabling circuit 04. The first terminal of the second switching transistor Q2 and the positive electrode of the first voltage stabilizing diode DW1 are grounded. The second terminal of the second switching transistor Q2, the negative electrode of the first voltage stabilizing diode DW1, and the positive electrode of the first diode D1 are connected to the first enabling terminal of the protection circuit 02. The negative electrode of the first diode D1 and the negative electrode of the second diode D2 are connected to the second enabling terminal of the protection circuit 02. The positive electrode of the second diode D2 is connected to the power supply terminal of the enabling circuit 04.

[0071] It should be noted that the enabling circuit 04 may further include a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. One end of the fifth resistor R5 is connected to the signal input terminal of the enabling circuit 04. The other end of the fifth resistor R5 is connected to one end of the seventh resistor R7. The other end of the seventh resistor R7 and one end of the sixth resistor R6 are connected to the controlled terminal of the second switching transistor Q2. The other end of the sixth resistor R6 is grounded. In this embodiment, the second switching transistor Q2 may be an NMOS transistor.

[0072] When the control circuit 03 inputs a high level, the second switching transistor Q2 conducts, and then the coil of the relay K has a 12V voltage, causing the relay K to be attracted, and its contacts 3 and 4 are conductively connected. At this time, the protection circuit 02 is in a working state. Among them, the first diode D1 can play an isolation role to protect the protection circuit 02 from the influence of transient reverse pulses. The second diode D2 can prevent reverse connection damage and prevent the reverse current from damaging the relay K when the power supply is accidentally reversely connected. The first voltage stabilizing diode DW1 can protect the second switching transistor Q2 from overvoltage. When the control circuit 03 inputs a low level, the second switching transistor Q2 turns off, and then the coil of the relay K loses the 12V voltage, causing the relay K to release its attraction, and its contacts 3 and 4 are connected. At this time, the protection circuit 02 is in a stopped working state.

[0073] Please refer to Figure 2 , in an embodiment of the present application, the short-circuit protection circuit further includes:

[0074] A signal amplification circuit 05. The input terminal of the signal amplification circuit 05 is connected to the signal output terminal of the current detection circuit 01. The first output terminal of the signal amplification circuit 05 is connected to the signal input terminal of the protection circuit 02. The second output terminal of the signal amplification circuit 05 is connected to the signal input terminal of the control circuit 03. The signal amplification circuit 05 is used to amplify the current detection signal and then output it.

[0075] Please refer to Figure 4, the signal amplification circuit 05 may include an eighth resistor R8 to a twelfth resistor R12, a first capacitor C1 to a fifth capacitor C5, a second zener diode DW2, and an amplifier U1. In this embodiment, the current detection signal is input to the non-inverting input terminal of the amplifier U1 through the D_A terminal, the BAT- signal is input to the inverting input terminal of the amplifier U1 through BAT-, and after being amplified by the amplifier U1, the current detection signal outputs a first current detection signal to the INTER_LOCK terminal of the signal amplification circuit 05 and outputs a second current detection signal to the SCD_DET terminal of the signal amplification circuit 05. Thus, in this embodiment, by setting the capacitance value of the first capacitor C1 and the resistance value of the eighth resistor R8, the amplification factor of the amplifier U1 can be adjusted, and by setting the resistance value of the ninth resistor R9, the voltage values of the output INTER_LOCK signal and SCD_DET signal can be adjusted and output to the protection circuit 02 and the control circuit 03 respectively, which can meet the output requirements of different current detection signals.

[0076] In an embodiment of the present application, in combination with Figures 2 to 5 , the technical principle of the embodiment of the present application is elaborated as follows:

[0077] Under normal operation, the control circuit 03 sends instructions to the charge and discharge circuit 06 to control the normal opening and operation of the charge and discharge circuit 06. The control circuit 03 sends instructions to make the SCC_CONTROL signal high level, controls the second switching transistor Q2 of the enable circuit 04 to turn on, and the coil of the relay K has 12V voltage, causing the relay K to be attracted, and the contacts 3 and 4 of the relay K to conduct; (the DSG signal of the contact 4 of the relay K is the drive signal for controlling the charge and discharge circuit 06). The short-circuit current flows through the thirteenth resistor R13 to the seventeenth resistor R17 of the current detection circuit 01, generates a current detection signal, and amplifies this signal 12 times through the amplifier U1 to generate the first current detection signal INTER_LOCK and the second current detection signal SCD_DET. The SCD_DET signal is sent to the control circuit 03, and the INTER_LOCK signal is sent to the protection circuit 02. The INTER_LOCK signal is sent to the first switching transistor Q1 (the turn-on threshold voltage of this MOS transistor is 1V), the first switching transistor Q1 conducts, pulls the contact 3 of the relay K to the BAT- voltage, that is, pulls the drive signal DSG of the charge and discharge circuit 06 down to BAT-, and makes the charge and discharge circuit 06 disconnect. After successful disconnection, the short-circuit current becomes 0, then the INTER_LOCK signal and the SCD_DET signal are also 0, the first switching transistor Q1 disconnects, the drive signal DSG returns to normal, the charge and discharge circuit 06 returns to normal, and then the short-circuit current flows through the current detection circuit 01 again, generating the corresponding INTER_LOCK signal and SCD_DET signal. The above steps repeat, the charge and discharge circuit 06 repeats opening and closing, and the current detection signal generates a pulsed waveform. At this time, the pulsed SCD_DET signal is also sent to the control circuit 03, and the control circuit 03 performs filtering and calculation processing on this pulsed signal. If the number of pulses of the SCD_DET signal reaches 40 within 3 seconds, it is considered that this signal is a real and effective short-circuit signal (the interference signal will not exist continuously within 3 seconds), then the control circuit 03 sends instructions to the charge and discharge circuit 06 again to control the charge and discharge circuit 06 to turn off. At the same time, the control circuit 03 reports the short-circuit protection event externally.

[0078] Based on the above principle, in this embodiment, a reliable short-circuit protection circuit can be built with simple resistors, capacitors, diodes, switching transistors, and relays, which has the characteristics of fast response speed, accurate detection, low implementation cost, and easy control. In the usage scenario of using lithium batteries of communication base stations as backup power supplies, it ensures the safety of on-site maintenance operators and the stable operation of communication base stations.

[0079] Please refer to Figure 6 , this application also proposes a short-circuit protection method, which is applied to a battery management system. The battery management system includes a charge and discharge circuit for controlling the charging / discharging of the battery; the short-circuit protection method includes steps S10 to S30:

[0080] Step S10, detect the charging current / discharging current of the battery, and output a corresponding current detection signal;

[0081] Step S20, when it is detected according to the current detection signal that there is a short circuit in the loop between the charge-discharge circuit and the battery, control the charge-discharge circuit to turn off; when it is detected that the loop between the charge-discharge circuit and the battery is normal, control the charge-discharge circuit to turn on;

[0082] Step S30, when it is determined according to the current detection signal that there is a short circuit in the loop between the charge-discharge circuit and the battery and it is effective, control the charge-discharge circuit to remain off.

[0083] In an embodiment of the present application, the step of controlling the charge-discharge circuit to turn off when it is detected according to the current detection signal that there is a short circuit in the loop between the charge-discharge circuit and the battery, and controlling the charge-discharge circuit to turn on when it is detected that the loop between the charge-discharge circuit and the battery is normal includes step S21:

[0084] Step S21, when it is determined according to the current detection signal that the current in the loop between the charge-discharge circuit and the battery is greater than a first preset threshold, control the charge-discharge circuit to turn off; and when the current detection signal determines that the current in the loop between the charge-discharge circuit and the battery is less than a second preset threshold, control the charge-discharge circuit to turn on; the first preset threshold is greater than the second preset threshold.

[0085] In an embodiment of the present application, the step of controlling the charge-discharge circuit to remain off when it is determined according to the current detection signal that there is a short circuit in the loop between the charge-discharge circuit and the battery and it is effective includes step S31:

[0086] Step S31, when the number of times that the voltage value of the current detection signal exceeds a third preset threshold within a preset time period is detected to reach a preset number of times, determine that the on / off frequency of the charge-discharge circuit reaches a preset frequency, and control the charge-discharge circuit to remain off.

[0087] The short-circuit protection method provided by the present application can solve the problems of slow response speed or easy occurrence of short-circuit false alarm events in the existing short-circuit protection solutions. Compared with the prior art, the beneficial effects of the embodiments of the short-circuit protection method provided by the present application are the same as those of the short-circuit protection circuit provided by the above embodiments, and will not be elaborated here.

[0088] The present application also provides a battery management system, which includes a charge / discharge circuit for controlling the charging / discharging of the battery and a short-circuit protection circuit. The specific structure of the short-circuit protection circuit refers to the above embodiments. Since the present battery management system adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0089] The above description is only an exemplary embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made under the technical concept of the present application by using the content of the specification and drawings of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A short - circuit protection circuit, applied to a battery management system, characterized in that, The battery management system includes a charge and discharge circuit for controlling the charging / discharging of the battery; The short - circuit protection circuit includes: A current detection circuit, the detection end of the current detection circuit is connected to one end of the battery, and the current detection circuit is used to detect the charging current / discharging current of the battery and output a corresponding current detection signal; A protection circuit, the control end of the protection circuit is connected to the first controlled end of the charge and discharge circuit, and the signal input end of the protection circuit is connected to the first output end of the current detection circuit; the protection circuit is used to control the charge and discharge circuit to turn off when detecting a loop short - circuit between the charge and discharge circuit and the battery according to the current detection signal, and control the charge and discharge circuit to turn on when detecting that the loop between the charge and discharge circuit and the battery is normal; A control circuit, the signal input end of the control circuit is connected to the second output end of the current detection circuit, and the first control end of the control circuit is connected to the second controlled end of the charge and discharge circuit; the control circuit is used to control the charge and discharge circuit to remain off when determining that the loop between the charge and discharge circuit and the battery is short - circuited and effective according to the current detection signal.

2. The short-circuit protection circuit according to claim 1, characterized in that, The protection circuit is specifically used for: When determining that the current of the loop between the charge and discharge circuit and the battery is greater than a first preset threshold according to the current detection signal, controlling the charge and discharge circuit to turn off; and when the current detection signal determines that the current of the loop between the charge and discharge circuit and the battery is less than a second preset threshold, controlling the charge and discharge circuit to turn on; the first preset threshold is greater than the second preset threshold.

3. The short-circuit protection circuit according to claim 1, wherein The control circuit is specifically used for: When the number of times that the voltage value of the current detection signal exceeds a third preset threshold within a preset time period is equal to a preset number of times, determining that the on / off frequency of the charge and discharge circuit reaches a preset frequency and controlling the charge and discharge circuit to remain off.

4. The short-circuit protection circuit according to claim 1, characterized in that, The protection circuit includes a relay and a first switching tube; the first end of the first switching tube is connected to the negative electrode of the battery, the second end of the first switching tube is connected to the first contact of the relay, the controlled end of the first switching tube is connected to the signal input end of the protection circuit, and the second contact of the relay is connected to the drive signal end of the charge and discharge circuit.

5. The short-circuit protection circuit according to claim 1, characterized in that, It further includes: An enable circuit, the signal input end of the enable circuit is connected to the second control end of the control circuit, and the enable end of the enable circuit is connected to the controlled end of the protection circuit; the enable circuit is used to control the protection circuit to work / stop working according to the enable signal output by the control circuit.

6. The short-circuit protection circuit according to claim 5, characterized in that, The enable circuit includes a second switching tube, a first voltage - stabilizing tube, a first diode and a second diode; The controlled terminal of the second switching transistor is connected to the signal input terminal of the enabling circuit. The first terminal of the second switching transistor and the positive electrode of the first voltage stabilizing diode are grounded. The second terminal of the second switching transistor, the negative electrode of the first voltage stabilizing diode, and the positive electrode of the first diode are connected to the first enabling terminal of the protection circuit. The negative electrode of the first diode and the negative electrode of the second diode are connected to the second enabling terminal of the protection circuit. The positive electrode of the second diode is connected to the power supply terminal of the enabling circuit.

7. The short-circuit protection circuit according to claim 1, wherein It further includes: A signal amplification circuit, the input terminal of the signal amplification circuit is connected to the signal output terminal of the current detection circuit, the first output terminal of the signal amplification circuit is connected to the signal input terminal of the protection circuit, and the second output terminal of the signal amplification circuit is connected to the signal input terminal of the control circuit; the signal amplification circuit is used to amplify the current detection signal and then output it.

8. A short-circuit protection method, applied to a battery management system, characterized in that, The battery management system includes a charge and discharge circuit for controlling the charging / discharging of the battery; the short-circuit protection method includes: Detecting the charging current / discharging current of the battery and outputting a corresponding current detection signal; When it is detected that the loop between the charge and discharge circuit and the battery is short-circuited according to the current detection signal, controlling the charge and discharge circuit to turn off, and when it is detected that the loop between the charge and discharge circuit and the battery is normal, controlling the charge and discharge circuit to turn on; When it is determined according to the current detection signal that the loop between the charge and discharge circuit and the battery is short-circuited and effective, controlling the charge and discharge circuit to remain off.

9. The short-circuit protection method according to claim 8, characterized in that The step of controlling the charge and discharge circuit to remain off when it is determined according to the current detection signal that the loop between the charge and discharge circuit and the battery is short-circuited and effective includes: When the number of times the voltage value of the current detection signal exceeds a third preset threshold within a preset time period is detected to reach a preset number of times, it is determined that the on / off frequency of the charge and discharge circuit reaches a preset frequency, and the charge and discharge circuit is controlled to remain off.

10. A battery management system, characterized in that, It includes a charge and discharge circuit for controlling the charging / discharging of the battery and the short-circuit protection circuit according to any one of claims 1 to 7.

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