CN221380592U - A from outage protection circuit for lithium battery BMS - Google Patents

A from outage protection circuit for lithium battery BMS Download PDF

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Publication number
CN221380592U
CN221380592U CN202323341044.4U CN202323341044U CN221380592U CN 221380592 U CN221380592 U CN 221380592U CN 202323341044 U CN202323341044 U CN 202323341044U CN 221380592 U CN221380592 U CN 221380592U
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resistor
mos tube
diode
bms
circuit
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朱广耀
席培栋
高佳鑫
吴昱增
熊一凡
原苡晗
裴浩洋
李会萍
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Henan University
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Henan University
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Abstract

The utility model discloses a self-outage protection circuit for a lithium battery BMS, which comprises an optical coupler, a power supply, a switch, a first MOS tube, a second MOS tube, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a capacitor, a first diode, a second diode and a third diode; the input end of the optocoupler is connected with a fault trigger protection pin of the BMS, and the output end of the optocoupler is connected with the grid electrode of the first MOS tube through a third diode; and the drain electrode of the second MOS tube is connected with a power input circuit of the BMS. According to the utility model, the battery is powered off by the self electrical characteristics when the BMS system fails and triggers protection, so that tiny current discharge of the lithium battery caused by the self power consumption of the BMS is avoided, overdischarge of the battery is caused under the condition of long-time unmanned intervention, the operability of the battery is improved, the service life of the battery is prolonged, and potential safety hazards of the battery caused by overdischarge are avoided.

Description

A from outage protection circuit for lithium battery BMS
Technical Field
The utility model relates to the technical field of lithium batteries, in particular to a self-power-off protection circuit for a lithium battery BMS.
Background
At present, the lithium ion storage battery has the characteristics of excellent charge and discharge characteristics, light weight, no maintenance, long service life and the like, and is widely applied to various flat-bed transport vehicles, electric forklifts and unmanned transport vehicles (Automated Guided Vehicle, AGVs) as a vehicle-mounted power battery pack, but the over-discharge condition of the battery pack often occurs due to improper human management and maintenance in the practical application process.
For example: when an AGV vehicle works, the AGV vehicle is not charged in time to trigger low-voltage protection (the Battery capacity is basically below 5% when the AGV vehicle triggers protection), although a Battery management system (Battery MANAGEMENT SYSTEM, BMS) can actively disconnect a load loop to avoid continuously discharging a Battery pack, a BMS circuit is always connected with the Battery pack through a switch in a closed mode, and as the power supply of the BMS circuit is continuously maintained by a Battery, once the AGV vehicle is not interfered by a person for a long time (generally 3-7 days according to different Battery capacities), the Battery cell voltage can be directly pulled down to an overdischarge state, and even if the AGV vehicle wants to be charged, the Battery cell voltage is too low, a charging control circuit cannot be started, so that the AGV vehicle cannot be charged. Therefore, even if a method is needed to directly charge the battery cell, most chargers do not work due to the fact that abnormal voltage is detected; even if the battery is charged and recovered by a method, the lithium precipitation reaction of the battery core can occur due to over-discharge, so that the internal resistance of the battery is increased, the service life is seriously damaged, and even the fire explosion accident is caused in extreme cases.
Disclosure of utility model
The utility model aims to provide a self-outage protection circuit for a lithium battery BMS, which can disconnect the BMS circuit from a battery when the BMS triggers protection so as to avoid continuous discharge loss of a lithium battery pack, and therefore the battery pack is not overdischarged even if the battery pack is placed for a long time.
The utility model adopts the technical scheme that:
The self-outage protection circuit for the lithium battery BMS comprises an optical coupler K1, a power supply, a switch S1, a first MOS tube V5, a second MOS tube V8, a first resistor R75, a second resistor R76, a third resistor R77, a fourth resistor R78, a fifth resistor R89, a capacitor C71, a first diode VD28, a second diode VD29 and a third diode VD32;
The input end of the optical coupler K1 is connected with a fault triggering protection pin of the BMS, the output end of the optical coupler K1 is connected with a grid electrode of a first MOS tube V5 through a third diode VD32, the grid electrode of the first MOS tube V5 is simultaneously connected with one ends of a third resistor R77 and a fourth resistor R78, the third resistor R77 and the fourth resistor R78 form a voltage dividing circuit, the other end of the fourth resistor R78 is grounded, the other end of the third resistor R77 is sequentially grounded through a capacitor C71 and the first resistor R75, the other end of the third resistor R77 is connected with a negative electrode of a first diode VD28, and the positive electrode of the first diode VD28 is grounded; the common connection end of the capacitor C71 and the first resistor R75 is connected with the positive electrode of the power supply through the switch S1 and is also connected with the source electrode of the second MOS tube V8; the drain electrode of the first MOS tube V5 is connected with the grid electrode of the second MOS tube V8 through a fifth resistor R89, the grid electrode of the second MOS tube V8 is respectively connected with one end of a second resistor R76 and the anode of a second diode VD29, and one end of the second resistor R76 and the cathode of the second diode VD29 are simultaneously connected with the source electrode of the second MOS tube V8; the drain electrode of the second MOS tube V8 is connected with a power input circuit of the BMS.
And the RC circuit is formed by the first resistor R75 and the capacitor C71, wherein the value of the first resistor R75 is 10MΩ, and the value of the capacitor C71 is 0.1uF.
The first MOS tube V5 adopts an N-channel small-signal MOSFET 2N7000 or VN10KN to control the on-off of the second MOS tube V8.
The second MOS tube V8 adopts a P-channel high-current MOSFET IRF9640PBF for switching on or switching off the working power supply of the BMS main loop.
The device also comprises a sixth resistor R12 and a seventh resistor R13, wherein the sixth resistor R12 is connected in series between a fault triggering protection pin of the BMS and the input end of the optical coupler K1, and is used as a current limiting resistor to prevent the K1 from receiving excessive current impact and improve the circuit stability; one end of the seventh resistor R13 is connected with the output end of the optical coupler K1, the other end of the seventh resistor R13 is grounded, the resistor is used as a pull-down resistor, and the pin is clamped to be at a low level when no output exists at the output end of the K1.
The power supply is a 24V battery pack, and the second diode VD29 adopts an 8.2V voltage stabilizing diode.
According to the utility model, the power supply input end of the lithium battery pack BMS is connected in series for use, after the circuit is adopted, even if a power switch of a battery is not normally turned off due to improper daily management, the power consumption of the circuit is lower than the normal self-consumption of a battery core by over 10M because the first resistor and the voltage dividing resistor are arranged between the positive electrode and the negative electrode of the power supply of the circuit input end, and the voltage breaking of the circuit at the back can be realized.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic circuit diagram of the present utility model.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the utility model comprises an optocoupler K1, a power supply, a switch S1, a first MOS transistor V5, a second MOS transistor V8, a first resistor R75, a second resistor R76, a third resistor R77, a fourth resistor R78, a fifth resistor R89, a capacitor C71, a first diode VD28, a second diode VD29, and a third diode VD32;
The input end of the optical coupler K1 is connected with a fault triggering protection pin of the BMS, the output end of the optical coupler K1 is connected with a grid electrode of a first MOS tube V5 through a third diode VD32, the grid electrode of the first MOS tube V5 is simultaneously connected with one ends of a third resistor R77 and a fourth resistor R78, the third resistor R77 and the fourth resistor R78 form a voltage dividing circuit, the other end of the fourth resistor R78 is grounded, the other end of the third resistor R77 is sequentially grounded through a capacitor C71 and the first resistor R75, the other end of the third resistor R77 is connected with a negative electrode of a first diode VD28, and the positive electrode of the first diode VD28 is grounded; the common connection end of the capacitor C71 and the first resistor R75 is connected with the positive electrode of the power supply through the switch S1 and is also connected with the source electrode of the second MOS tube V8; the drain electrode of the first MOS tube V5 is connected with the grid electrode of the second MOS tube V8 through a fifth resistor R89, the grid electrode of the second MOS tube V8 is respectively connected with one end of a second resistor R76 and the anode of a second diode VD29, and one end of the second resistor R76 and the cathode of the second diode VD29 are simultaneously connected with the source electrode of the second MOS tube V8; the drain electrode of the second MOS tube V8 is connected with a power input circuit of the BMS;
The device also comprises a sixth resistor R12 and a seventh resistor R13, wherein the sixth resistor R12 is connected in series between a fault triggering protection pin of the BMS and the input end of the optical coupler K1, and is used as a current limiting resistor to prevent the K1 from receiving excessive current impact and improve the circuit stability; one end of the seventh resistor R13 is connected with the output end of the optical coupler K1, the other end of the seventh resistor R13 is grounded, the resistor is used as a pull-down resistor, and the pin is clamped to be at a low level when no output exists at the output end of the K1.
In practical use, the RC circuit is composed of the first resistor R75 and the capacitor C71, the value of the first resistor R75 is 10MΩ, and the value of the capacitor C71 is 0.1uF. The first MOS tube V5 adopts an N-channel small-signal MOSFET 2N7000 or VN10KN to control the on-off of the second MOS tube V8. The second MOS tube V8 adopts a P-channel high-current MOSFET IRF9640PBF for switching on or switching off the working power supply of the BMS main loop. The power supply is a 24V battery pack, the second diode VD29 adopts an 8.2V voltage-stabilizing diode, the protection of an AGV charging module of the BSM with the model of the singlechip of C8051F041 can be met, and a trigger protection pin of the singlechip D1 is connected with a 55 pin as shown in the figure.
Specifically, in a 24V battery system: s1 is closed, by utilizing the characteristic of capacitive isolation direct current, the first capacitor C71 is instantly conducted to add battery cell voltage +24V to the 1 pin of the N-channel first MOS tube V5, the first MOS tube V5 works for 2-3 pins to be conducted, the second diode VD29 clamps the 1 pin of the P-channel second MOS tube V8 to 8.2V, the second MOS tube V8 works to trigger the 2-3 pins to be closed, current is led to a subsequent circuit, and voltage of each stage required by the BMS circuit and the singlechip C8051F041 (D1) is provided through an inductor L1, a power supply conversion circuit and the like. In fig. 1, the circuit connected with other pins on the singlechip D1 and the BMS circuit connected with the V8 output pin in the subsequent step are omitted.
After the singlechip D1 works, the corresponding 55 pins are pulled to a high level, and the optocoupler AQY EH (K1) is triggered to continuously provide maintenance working voltage for the first MOS tube V5, so that the first MOS tube V5 always keeps a conducting working state. At this time, the post-stage BMS circuit starts to operate after the required voltage is obtained.
When the BMS system fails and needs to be triggered for protection, the pin of the D1 singlechip 55 is changed from high level to low level. Because pin 1 of the optocoupler K1 is low, pin 3 of the optocoupler K1 is pulled down immediately, and at this time, the capacitor C71 is in an open circuit state for direct current, so pin 1 of the first MOS transistor V5 stops working due to the low level, and the second MOS transistor V8 also stops working, even if the switch S1 is still in a closed state, but the input of the power supply of the later-stage BMS circuit is in a no-input voltage state, at this time, because the first resistor R75 is 10M ohms, which means that only 2.4uA of power is consumed on the resistor, and the capacitor C71 is in an open circuit state in the direct current state, so that the whole circuit is in a complete power-off state and will not consume power of the battery cells. The first diode VD28 can accelerate the discharge of the capacitor C71, so as not to affect the next start-up of the BMS system.
When restarting is needed, the whole BMS circuit can work normally only by opening the switch S1 and closing the switch.
In summary, the device is divided into three stages in actual operation:
In the first stage, the BMS circuit is powered on. After the switch S1 is closed, the current instantaneously passes through the capacitor C71, so that the first MOS transistor V5 is turned on, and the pin 1 of the second MOS transistor V8 is clamped to the turn-on voltage by the second diode VD 29. At this time, pins 2 and 3 of the second MOS tube V8 are conducted, and current can enter the BMS circuit and the singlechip D1 to provide required voltages for the BMS development board and the MCU.
The second stage is a work maintenance stage. When the singlechip D1 or the MCU runs a program after being started, the voltage of a corresponding control pin is pulled high, and the pin continuously supplies power to the first MOS tube V5 by triggering the optocoupler, so that the BMS circuit can continuously work.
The third phase is an important power-off protection phase. When the system fails, the MCU pulls down the voltage of the corresponding pin when detecting that power-off protection is needed, at the moment, the optocoupler K1 does not output, and the pins 2 and 3 of the first MOS tube V5 are disconnected, so that each circuit component of the subsequent BMS stops working because of circuit disconnection.
The utility model is applied to the power input end of the lithium battery pack BMS, has simple circuit and high reliability, has small change to the original circuit, can be used as long as the circuit is connected in series to the BMS power input end, and even if the battery power is not normally turned off due to improper daily management after the circuit is adopted, the power consumption is lower than the normal self-consumption of the battery core by almost negligible due to the extremely high resistance of more than 10M adopted between the positive electrode and the negative electrode of the power source of the circuit input end.
In the description of the present invention, it should be noted that, for the azimuth words such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the azimuth and positional relationships are based on the azimuth or positional relationships shown in the drawings, it is merely for convenience of describing the present invention and simplifying the description, and it is not to be construed as limiting the specific scope of protection of the present invention that the device or element referred to must have a specific azimuth configuration and operation.
It should be noted that the terms "comprises" and "comprising," along with any variations thereof, in the description and claims of the present application are intended to cover a non-exclusive inclusion, such as a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus.
Note that the above is only a preferred embodiment of the present invention and uses technical principles. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the present invention has been described in connection with the above embodiments, it is to be understood that the invention is not limited to the specific embodiments disclosed and that many other and equally effective embodiments may be devised without departing from the spirit of the invention, and the scope thereof is determined by the scope of the appended claims.

Claims (6)

1. A from outage protection circuit for lithium battery BMS, its characterized in that: the circuit comprises an optical coupler K1, a power supply, a switch S1, a first MOS tube V5, a second MOS tube V8, a first resistor R75, a second resistor R76, a third resistor R77, a fourth resistor R78, a fifth resistor R89, a capacitor C71, a first diode VD28, a second diode VD29 and a third diode VD32;
The input end of the optical coupler K1 is connected with a fault triggering protection pin of the BMS, the output end of the optical coupler K1 is connected with a grid electrode of a first MOS tube V5 through a third diode VD32, the grid electrode of the first MOS tube V5 is simultaneously connected with one ends of a third resistor R77 and a fourth resistor R78, the third resistor R77 and the fourth resistor R78 form a voltage dividing circuit, the other end of the fourth resistor R78 is grounded, the other end of the third resistor R77 is sequentially grounded through a capacitor C71 and the first resistor R75, the other end of the third resistor R77 is connected with a negative electrode of a first diode VD28, and the positive electrode of the first diode VD28 is grounded; the common connection end of the capacitor C71 and the first resistor R75 is connected with the positive electrode of the power supply through the switch S1 and is also connected with the source electrode of the second MOS tube V8; the drain electrode of the first MOS tube V5 is connected with the grid electrode of the second MOS tube V8 through a fifth resistor R89, the grid electrode of the second MOS tube V8 is respectively connected with one end of a second resistor R76 and the anode of a second diode VD29, and one end of the second resistor R76 and the cathode of the second diode VD29 are simultaneously connected with the source electrode of the second MOS tube V8; the drain electrode of the second MOS tube V8 is connected with a power input circuit of the BMS.
2. The self-power-off protection circuit for a lithium battery BMS according to claim 1, wherein: and the RC circuit is formed by the first resistor R75 and the capacitor C71, wherein the value of the first resistor R75 is 10MΩ, and the value of the capacitor C71 is 0.1uF.
3. The self-power-off protection circuit for a lithium battery BMS according to claim 1, wherein: the first MOS tube V5 adopts an N-channel small-signal MOSFET 2N7000 or VN10KN to control the on-off of the second MOS tube V8.
4. The self-power-off protection circuit for a lithium battery BMS according to claim 1, wherein: the second MOS tube V8 adopts a P-channel high-current MOSFET IRF9640PBF for switching on or switching off the working power supply of the BMS main loop.
5. The self-power-off protection circuit for a lithium battery BMS according to claim 1, wherein: the device also comprises a sixth resistor R12 and a seventh resistor R13, wherein the sixth resistor R12 is connected in series between a fault triggering protection pin of the BMS and the input end of the optical coupler K1, and is used as a current limiting resistor to prevent the K1 from receiving excessive current impact and improve the circuit stability; one end of the seventh resistor R13 is connected with the output end of the optical coupler K1, the other end of the seventh resistor R13 is grounded, the resistor is used as a pull-down resistor, and the pin is clamped to be at a low level when no output exists at the output end of the K1.
6. The self-power-off protection circuit for a lithium battery BMS according to claim 1, wherein: the power supply is a 24V battery pack, and the second diode VD29 adopts an 8.2V voltage stabilizing diode.
CN202323341044.4U 2023-12-08 2023-12-08 A from outage protection circuit for lithium battery BMS Active CN221380592U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202323341044.4U CN221380592U (en) 2023-12-08 2023-12-08 A from outage protection circuit for lithium battery BMS

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202323341044.4U CN221380592U (en) 2023-12-08 2023-12-08 A from outage protection circuit for lithium battery BMS

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CN221380592U true CN221380592U (en) 2024-07-19

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