CN216959400U - Light current switch circuit of lithium battery management system - Google Patents
Light current switch circuit of lithium battery management system Download PDFInfo
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- CN216959400U CN216959400U CN202220576256.7U CN202220576256U CN216959400U CN 216959400 U CN216959400 U CN 216959400U CN 202220576256 U CN202220576256 U CN 202220576256U CN 216959400 U CN216959400 U CN 216959400U
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- resistor
- bms
- pole
- pmos tube
- switch
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 17
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 17
- 239000003990 capacitor Substances 0.000 claims abstract description 4
- 230000015556 catabolic process Effects 0.000 abstract description 2
- 238000002955 isolation Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
A weak current switch circuit of a lithium battery management system comprises: a resistor R28 connected with the positive electrode of the switch is connected with the G pole of the PMOS tube, a resistor R29 and a capacitor C35 are connected in parallel between the G pole and the S pole of the PMOS tube, a 3.3V direct-current power supply is sequentially connected in series with a resistor R8 and a resistor R and then connected with the 44 pin of the BMS processing chip, the joint of the resistor R8 and the resistor R9 is connected with the D pole of the PMOS tube, and the S pole of the PMOS tube is grounded; the cathode of the diode D9 is used for connecting the negative pole of the switch, and the anode of the diode D9 is connected with 3.3V direct current through a fifth resistor. The utility model solves the problem of ground isolation of the conventional common switch circuit; the reverse voltage of the whole vehicle is prevented from being connected to the BMS common ground; preventing over 50MA reverse current from flowing into BMS common ground; damage to a BMS front-end equalization circuit is avoided; the short circuit of the BMS voltage acquisition circuit is avoided; reverse voltage breakdown of the processing chip is avoided; damage to the BMS main power supply circuit is avoided.
Description
Technical Field
The utility model relates to the technical field of switch circuits, in particular to a weak current switch circuit of a lithium battery management system.
Background
As shown in fig. 1, the working process of the lithium battery management system is as follows: when a battery module voltage sampling wire harness is connected with a BMS (lithium battery management system), when the module voltage is larger than a certain value, a BMS front-end chip or a BMS power supply circuit (part of which needs to be enabled by a power management IC) starts to work and provides direct-current working voltage VCC, a BMS processing chip main program starts self-checking to finish starting, after abnormal events do not exist, the state of a weak current switching circuit starts to be judged, when a switch is in an off state, the BMS detects that the switching state is high level, at the moment, a power output MOS (metal oxide semiconductor) tube is in a cut-off state, and the battery output is cut off; when the switch is in a closed state, the BMS detects that the switch state is a low level, the power output MOS tube is in a conducting state at the moment, and the battery can output power.
Fig. 2 is a prior art weak current switch circuit, the components of the weak current switch circuit and the working principle thereof:
1. the conventional weak current switch circuit is generally only provided with a diode D9 at the anode of the switch to prevent the influence of reverse high voltage on the chip U2, and the cathode of the switch is directly grounded;
2. the working principle is as follows: by means of the fact that the 44 pin on the single chip microcomputer is configured to be pulled up, when the external switch is switched off, the 44 pin is at a high level due to the fact that the pull-up voltage exists, the single chip microcomputer judges that the switch is switched off, when the external switch is switched off, the pull-up voltage of the 44 pin is directly conducted to the ground voltage and is 0, namely, the low level state, and the single chip microcomputer judges that the switch is in a closed state.
The weak current switch circuit has the following defects: the circuit has no function of preventing reverse high voltage, and is easy to burn out. How to provide a weak current switch circuit for preventing reverse high voltage of a lithium battery management system is a technical problem to be solved in the field.
SUMMERY OF THE UTILITY MODEL
The present invention is directed to a weak current switch circuit of a lithium battery management system, so as to solve the problems in the background art.
In order to achieve the purpose, the utility model provides the following technical scheme:
a weak current switch circuit of a lithium battery management system comprises: a first resistor R28 used for connecting one end with the positive electrode of the switch, the other end of the first resistor R28 is connected with the G electrode of the PMOS tube, a second resistor R29 and a capacitor C35 are connected in parallel between the G electrode and the S electrode of the PMOS tube, a 3.3V direct-current power supply is connected in series with a third resistor R8 and a fourth resistor R9 in sequence and then connected with the 44 pin of a lithium battery management system processing chip, also called a BMS processing chip U2, the connection point of the third resistor R8 and the fourth resistor R9 is connected with the D electrode of the PMOS tube, and the S electrode of the PMOS tube is grounded; the cathode of the diode D9 is used for connecting the negative pole of the switch, and the anode of the diode D9 is connected with a 3.3V direct current power supply through a fifth resistor.
Compared with the prior art, the utility model has the beneficial effects that: the utility model solves the problem of ground isolation of the conventional common switch circuit; the reverse voltage of the whole vehicle is prevented from being connected to the common ground of a lithium Battery Management System (BMS); preventing over 50MA reverse current from flowing into BMS common ground; damage to a BMS front-end equalization circuit is avoided; the short circuit of the BMS voltage acquisition circuit is avoided; the reverse voltage breakdown of the BMS MCU is avoided; damage to the BMS main power supply circuit is avoided; improving signal fluctuation caused by poor contact of the switch; the problem of over sensitivity of the common-ground reverse high-voltage micro short circuit is avoided (optional); and the safety protection level of the battery management system is improved.
Drawings
Fig. 1 is a schematic structural diagram of a lithium battery management system in the prior art;
FIG. 2 is a prior art switching circuit;
fig. 3 is a schematic circuit diagram of a weak current switch circuit of the lithium battery management system of the present application.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Example (b): as shown in fig. 3, a weak current switch circuit of a lithium battery management system includes: a first resistor R28 used for connecting one end with the positive electrode of the switch, the other end of the first resistor R28 is connected with the G pole of a PMOS tube Q2, a second resistor R29 and a capacitor C35 are connected in parallel between the G pole and the S pole of the PMOS tube, a 3.3V direct-current power supply is sequentially connected in series with a third resistor R8 and a fourth resistor R9 and then connected with the 44 pin of a lithium battery management system processing chip, also called a BMS processing chip U2, the junction of the third resistor R8 and the fourth resistor R9 is connected with the D pole of the PMOS tube, and the S pole of the PMOS tube is grounded; the cathode of the diode D9 is used for connecting the negative pole of the switch, and the anode of the diode D9 is connected with a 3.3V direct current power supply through a fifth resistor.
The working principle of the circuit is as follows: a 3.3V pull-up direct current voltage is provided, when the switch is switched off, the PMOS tube Q2 is switched off, the pin 44 of the BMS processing chip U2 is in a high level state, and the third resistor R8 and the fourth resistor R9 mainly play roles in clamping voltage and limiting current;
p-channel MOS tube (also called PMOS tube) switching circuit analysis: the starting condition of the switch circuit is that the VGS voltage is negative voltage, the absolute value of the voltage is greater than the lowest starting voltage, the minimum starting voltage of a general low-power PMOS tube is about 0.7V, the voltage is 4.2V and VGS = -4.2V under the condition that the battery is fully charged, the PMOS tube is conducted, and the circuit is free of problems. When the voltage is 5V, the voltage of the G pole is 5V, the voltage of the S pole is 5V-diode drop (about 0.5) =4.5V, and the PMOS tube is turned off; when no voltage of 5V exists, the voltage of the G pole is pulled down to be 0V, the voltage of the S pole is the voltage of the battery (the battery is fully charged by 4.2V) -the MOS tube does not conduct the diode drop (0.5V) =3.7, so that the PMOS tube is conducted, the diode drop does not exist, the VGS = -4.2V is formed, and the PMOS tube is conducted to supply power to the load. This problem is also solved by a schottky diode (SS 12), but with a voltage drop of around 0.3V. The PMOS tube is used, is completely conducted, has small internal resistance, is superior to Schottky and has almost no voltage drop. However, the pull-down resistor is a little bit large, the current is not needed for driving the PMOS, only the voltage is reached, the large resistor can be used, the working current is reduced, and the resistor of about 10K-100K is recommended to be used.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.
Claims (1)
1. A weak current switch circuit of a lithium battery management system is characterized by comprising: the power supply circuit comprises a first resistor (R28) used for connecting one end of the first resistor (R28) with the positive electrode of a switch, a second resistor (R29) and a capacitor (C35) are connected between the G electrode and the S electrode of a PMOS tube in parallel, a 3.3V direct-current power supply is sequentially connected with a third resistor (R8) and a fourth resistor (R9) in series and then connected with a 44 pin of a processing chip of a lithium battery management system, the connection point of the third resistor (R8) and the fourth resistor (R9) is connected with the D electrode of the PMOS tube, and the S electrode of the PMOS tube is grounded; the cathode of the diode (D9) is used for connecting the negative pole of the switch, and the anode of the diode (D9) is connected with the 3.3V direct current power supply through a fifth resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220576256.7U CN216959400U (en) | 2022-03-16 | 2022-03-16 | Light current switch circuit of lithium battery management system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220576256.7U CN216959400U (en) | 2022-03-16 | 2022-03-16 | Light current switch circuit of lithium battery management system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216959400U true CN216959400U (en) | 2022-07-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202220576256.7U Active CN216959400U (en) | 2022-03-16 | 2022-03-16 | Light current switch circuit of lithium battery management system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216959400U (en) |
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2022
- 2022-03-16 CN CN202220576256.7U patent/CN216959400U/en active Active
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| GR01 | Patent grant | ||
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Address after: 215300, 1st and 2nd floors, Zone B, Jindu Science and Technology Innovation Industrial Park, No. 55 Lisheng Road, Huaqiao Town, Kunshan City, Suzhou City, Jiangsu Province Patentee after: Suzhou Liansheng New Energy Technology Co.,Ltd. Country or region after: China Address before: 215127 1st floor, building 1, No. 8, CHENGWAN Road, Suzhou Industrial Park, Wuzhong District, Suzhou City, Jiangsu Province Patentee before: Suzhou Liansheng New Energy Technology Co.,Ltd. Country or region before: China |
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