CN111751755A - Insulation monitoring circuit of lithium battery pack and monitoring method thereof - Google Patents
Insulation monitoring circuit of lithium battery pack and monitoring method thereof Download PDFInfo
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- CN111751755A CN111751755A CN202010612872.9A CN202010612872A CN111751755A CN 111751755 A CN111751755 A CN 111751755A CN 202010612872 A CN202010612872 A CN 202010612872A CN 111751755 A CN111751755 A CN 111751755A
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- 238000009413 insulation Methods 0.000 title claims abstract description 70
- 238000012544 monitoring process Methods 0.000 title claims abstract description 31
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 13
- 238000000034 method Methods 0.000 title claims abstract description 9
- 238000005070 sampling Methods 0.000 claims abstract description 18
- 238000001514 detection method Methods 0.000 claims abstract description 15
- 238000010586 diagram Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/025—Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Secondary Cells (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
An insulation monitoring circuit of a lithium battery pack and a monitoring method thereof comprise a battery cluster, a voltage detection module, a sampling operational amplifier circuit, a digital processing module, a fault alarm module, a double-pole single-throw switch, equivalent insulation resistance and a plurality of resistors; the positive electrode and the negative electrode of the battery cluster are respectively connected with two resistors; the battery cluster is connected with equivalent insulation resistance, the equivalent insulation resistance is divided into two paths, one path is grounded, and the other path and the negative electrode of the battery cluster are respectively connected with a voltage detection module, a sampling operational amplifier circuit, a digital processing module and a fault alarm module in sequence; double-pole single-throw switches are arranged between the two resistors on the positive side of the battery cluster and the equivalent insulation resistance and between the two resistors on the negative side of the battery cluster and the equivalent insulation resistance. The invention has low cost and simple realization.
Description
Technical Field
The invention belongs to the technical field of battery insulation monitoring, and particularly relates to an insulation monitoring circuit of a lithium battery pack and a monitoring method thereof.
Background
A Battery Management System (BMS) is a link between a Battery and a user, and a primary object is a secondary Battery. The secondary battery has some disadvantages such as a small amount of stored energy, a short life, a problem of series-parallel use, safety in use, difficulty in estimating the amount of electricity of the battery, etc. The performance of the battery is complex and the characteristics of different types of batteries vary widely. A Battery Management System (BMS) is mainly to improve the utilization rate of a battery, prevent overcharge and overdischarge of the battery, extend the life span of the battery, and monitor the state of the battery.
The current battery management system does not have an insulation monitoring function generally, can not detect the change of the insulation condition of the battery pack in real time and dynamically, and is not beneficial to the safe use of the battery box.
Disclosure of Invention
The invention aims to provide an insulation monitoring circuit of a lithium battery pack and a monitoring method thereof, so as to solve the problems.
In order to achieve the purpose, the invention adopts the following technical scheme:
an insulation monitoring circuit of a lithium battery pack comprises a battery cluster, a voltage detection module, a sampling operational amplifier circuit, a digital processing module, a fault alarm module, a double-pole single-throw switch, equivalent insulation impedance and a plurality of resistors; the positive electrode and the negative electrode of the battery cluster are respectively connected with two resistors; the battery cluster is connected with equivalent insulation resistance, the equivalent insulation resistance is divided into two paths, one path is grounded, and the other path and the negative electrode of the battery cluster are respectively connected with a voltage detection module, a sampling operational amplifier circuit, a digital processing module and a fault alarm module in sequence; double-pole single-throw switches are arranged between the two resistors on the positive side of the battery cluster and the equivalent insulation resistance and between the two resistors on the negative side of the battery cluster and the equivalent insulation resistance.
Furthermore, the battery cluster consists of a plurality of batteries which are connected in series to form a battery string, and the plurality of batteries are connected in series to form the battery cluster; the insulation resistance of each battery to the case is RsnpnAnd finally, adding the equivalent insulation resistance Ri to the insulation resistance of all the batteries.
Further, the resistors are a resistor R1, a resistor R2, a resistor R3 and a resistor R4; the two resistors on the positive side of the battery cluster are a resistor R1 and a resistor R3, and the two resistors on the negative side of the battery cluster are a resistor R2 and a resistor R4; the resistance values of R3 and R4 are much smaller than those of R1 and R2.
Further, R1 and R3 are switched through S1, and R2 and R4 are switched through S2.
Further, a monitoring method of an insulation monitoring circuit of a lithium battery pack comprises the following steps:
step 2, resetting S1, switching back to R1, switching S2, connecting to R4, taking the voltage sampling value of the battery cathode as UE2 through Earth, and obtaining a formula II according to a node current equation:
step 3, listing the equivalent insulation resistance of the whole battery box body to obtain a formula III:
step 4, solving the equations with the first, second and third formulas to obtain a formula four as follows:
step 5, comparing the result of the formula IV with a protection threshold value set in a program so as to judge whether the battery box body has insulation fault;
step 6: after the processor processes the monitoring signals, if insulation monitoring faults exist, the processor transmits the insulation monitoring fault signals to the host computer so as to remind relevant workers to check.
Compared with the prior art, the invention has the following technical effects:
according to the invention, through the change-over switch and the matching of sampling feedback signals, the insulation detection of the battery box body can be effectively and reliably realized through the calculation of an internal formula of the processor;
according to the invention, through the cyclic processing of the processor, the insulation detection of the battery box body can be effectively realized in real time;
the invention mainly comprises S1, S2 and two groups of resistors, and has low cost and simple realization.
Drawings
FIG. 1 is an equivalent diagram of the insulation resistance detection of the battery according to the present invention.
FIG. 2 is a schematic diagram of an equivalent switch mode for detecting insulation resistance of a battery according to the present invention.
Fig. 3 is a schematic diagram of the insulation resistance detection switch mode of the battery according to the present invention.
FIG. 4 is a flow chart of the insulation monitoring software of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
referring to fig. 1 to 4, an insulation monitoring circuit of a lithium battery pack includes a battery cluster, a voltage detection module, a sampling operational amplifier circuit, a digital processing module, a fault alarm module, a double-pole single-throw switch, an equivalent insulation resistance and a plurality of resistors; the positive electrode and the negative electrode of the battery cluster are respectively connected with two resistors; the battery cluster is connected with equivalent insulation resistance, the equivalent insulation resistance is divided into two paths, one path is grounded, and the other path and the negative electrode of the battery cluster are respectively connected with a voltage detection module, a sampling operational amplifier circuit, a digital processing module and a fault alarm module in sequence; double-pole single-throw switches are arranged between the two resistors on the positive side of the battery cluster and the equivalent insulation resistance and between the two resistors on the negative side of the battery cluster and the equivalent insulation resistance.
The battery cluster consists of a plurality of batteries which are connected in series to form a battery string, and the plurality of batteries are connected in series and in parallel to form the battery cluster; the insulation resistance of each battery to the case is RsnpnAnd finally, adding the equivalent insulation resistance Ri to the insulation resistance of all the batteries.
The resistors are a resistor R1, a resistor R2, a resistor R3 and a resistor R4; the two resistors on the positive side of the battery cluster are a resistor R1 and a resistor R3, and the two resistors on the negative side of the battery cluster are a resistor R2 and a resistor R4; the resistance values of R3 and R4 are much smaller than those of R1 and R2.
And R1 and R3 are switched through S1, and R2 and R4 are switched through S2.
Fig. 1 is an equivalent schematic diagram of a battery box unit and its insulation monitoring circuit, assuming that the insulation resistance of each battery to the casing is Rs × b, and the final equivalent insulation resistance value Ri is the insulation sum of all batteries. In the circuit design, the resistance values of R3 and R4 are much smaller than the resistance values of R1 and R2. Wherein R1, R3 are switched through S1, R2, R4 are switched through S2, S1, S2 are double-pole single-throw switches.
A first switching mode:
the initial state of S1 is connected to R1, the initial state of S2 is connected to R2, after the processor starts the insulation detection function, S1 is firstly switched from R1 to R3, S2 is kept connected to R2, as shown in FIG. 2, the voltage sampling value of Earth to the negative pole of the battery is UE1, the voltage sampling value of the positive pole to the negative pole of the battery is UBAT +, and the following equations can be listed according to the node current:
and a second switching mode:
then S1 is reset, and then goes back to R1, S2 and S2, and then goes back to R4, as shown in fig. 3, at this time, Earth samples the voltage of the battery cathode to be UE2, and at this time, the following equations can be listed according to the node current:
calculating the insulation equivalent impedance:
wherein the equivalent insulation resistance of the whole battery pack is:
Rs1p1+Rs1p2+......+Rs1pn+Rs1p1+Rs1p2+......+Rs2pn+Rs2p1+Rs2p2+......+Rsnpn＝Ri(formula three)
Solving the equations with the first, second and third equations can obtain a fourth equation as follows:
software flow chart:
as shown in fig. 4, which is a software flow chart of insulation monitoring, after insulation monitoring is started, S1 and S2 maintain an initial state, then S1 is switched, S2 maintains an original state, state maintaining time is T1, during this time, the processor samples UE1 and a voltage sampling value UBAT + of a battery anode and a battery cathode, and then S1 resets, S2 is switched, and T1 is also maintained, at this time, the processor samples UE2, and finally S2 is reset, so that S1 and S2 both recover the original state, the processor calculates a final equivalent resistance by calling a formula, when the calculated resistance value is greater than a set protection threshold value, the processor passes the detection, determines that the insulation impedance is normal, and when the calculated resistance value is less than the set protection threshold value, the processor fails the detection, determines that the insulation impedance is not normal, and reports a system error report.
Claims (5)
1. An insulation monitoring circuit of a lithium battery pack is characterized by comprising a battery cluster, a voltage detection module, a sampling operational amplifier circuit, a digital processing module, a fault alarm module, a double-pole single-throw switch, equivalent insulation resistance and a plurality of resistors; the positive electrode and the negative electrode of the battery cluster are respectively connected with two resistors; the battery cluster is connected with equivalent insulation resistance, the equivalent insulation resistance is divided into two paths, one path is grounded, and the other path and the negative electrode of the battery cluster are respectively connected with a voltage detection module, a sampling operational amplifier circuit, a digital processing module and a fault alarm module in sequence; double-pole single-throw switches are arranged between the two resistors on the positive side of the battery cluster and the equivalent insulation resistance and between the two resistors on the negative side of the battery cluster and the equivalent insulation resistance.
2. The insulation monitoring circuit of a lithium battery pack as claimed in claim 1, wherein the battery cluster is composed of a plurality of batteries, the plurality of batteries are connected in series to form a battery string, and the plurality of battery strings are connected in parallel to form the battery cluster; the insulation resistance of each battery to the case is RsnpnAnd finally, adding the equivalent insulation resistance Ri to the insulation resistance of all the batteries.
3. The insulation monitoring circuit of a lithium battery pack as claimed in claim 1, wherein the plurality of resistors are a resistor R1, a resistor R2, a resistor R3 and a resistor R4; the two resistors on the positive side of the battery cluster are a resistor R1 and a resistor R3, and the two resistors on the negative side of the battery cluster are a resistor R2 and a resistor R4; the resistance values of R3 and R4 are much smaller than those of R1 and R2.
4. The insulation monitoring circuit of the lithium battery pack as claimed in claim 3, wherein R1 and R3 are switched through S1, and R2 and R4 are switched through S2.
5. A monitoring method of an insulation monitoring circuit of a lithium battery pack, which is based on any one of claims 1 to 4, and comprises the following steps:
step 1, the processor starts a self-checking function, S1 is switched from R1 to R3, S2 is kept connected to R2, the voltage sampling value of the battery cathode through Earth is UE1, the voltage sampling value of the battery anode is UBAT +, and a formula I is obtained according to a node current equation:
step 2, resetting S1, switching back to R1, switching S2, connecting to R4, taking the voltage sampling value of the battery cathode as UE2 through Earth, and obtaining a formula II according to a node current equation:
step 3, listing the equivalent insulation resistance of the whole battery box body to obtain a formula III:
step 4, solving the equations with the first, second and third formulas to obtain a formula four as follows:
step 5, comparing the result of the formula IV with a protection threshold value set in a program so as to judge whether the battery box body has insulation fault;
step 6: after the processor processes the monitoring signals, if insulation monitoring faults exist, the processor transmits the insulation monitoring fault signals to the host computer so as to remind relevant workers to check.
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| CN202010612872.9A CN111751755A (en) | 2020-06-30 | 2020-06-30 | Insulation monitoring circuit of lithium battery pack and monitoring method thereof |
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| CN202010612872.9A CN111751755A (en) | 2020-06-30 | 2020-06-30 | Insulation monitoring circuit of lithium battery pack and monitoring method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112540275A (en) * | 2020-12-28 | 2021-03-23 | 上海瑞浦青创新能源有限公司 | Insulation monitoring system and method for energy storage unit |
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- 2020-06-30 CN CN202010612872.9A patent/CN111751755A/en active Pending
Patent Citations (9)
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| CN103033729A (en) * | 2012-11-26 | 2013-04-10 | 浙江高泰昊能科技有限公司 | Insulation detection circuit and detection method used for battery box |
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| EP3617719A1 (en) * | 2018-08-31 | 2020-03-04 | Contemporary Amperex Technology Co., Limited | Insulation detection method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112540275A (en) * | 2020-12-28 | 2021-03-23 | 上海瑞浦青创新能源有限公司 | Insulation monitoring system and method for energy storage unit |
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Effective date of registration: 20221216 Address after: Room 501, Zone B, Financial Investment Integrated Circuit Industrial Park, No. 5, Guanshan Road, Xinwu District, Wuxi City, Jiangsu Province, 214029 Applicant after: Jiangsu Ping'an New Energy Technology Co.,Ltd. Address before: Room 2963, 14C, No. 309, Tanggu Road, Hongkou District, Shanghai, 200080 Applicant before: Shanghai Pingan New Energy Technology Co.,Ltd. |
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Application publication date: 20201009 |
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