CN106786922B - Passive equalization circuit and method of battery management system - Google Patents
Passive equalization circuit and method of battery management system Download PDFInfo
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- CN106786922B CN106786922B CN201611241791.2A CN201611241791A CN106786922B CN 106786922 B CN106786922 B CN 106786922B CN 201611241791 A CN201611241791 A CN 201611241791A CN 106786922 B CN106786922 B CN 106786922B
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- equalization
- equalizing
- control circuit
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
- H02J7/0019—Circuits for equalisation of charge between batteries using switched or multiplexed charge circuits
Abstract
The invention discloses a passive equalization circuit and a passive equalization method of a battery management system. The passive equalization circuit comprises a plurality of batteries connected in series, an equalization loop and an acquisition control circuit which are connected with each battery in series, and is characterized by further comprising: matching a resistor; the matching resistor is used for performing differential impedance matching when the acquisition control circuit acquires voltage; one end of the acquisition control circuit is connected with the first end of each equalization loop, the other end of the acquisition control circuit is connected with the second end of each equalization loop through the matching resistor, the acquisition control circuit is used for controlling the connection or disconnection of each equalization loop, voltage acquisition is carried out, and whether the equalization loops fail or not is identified according to the acquired voltage. The invention not only can realize the passive equalization of the battery, but also can judge whether the equalization switch is invalid or not through the acquisition control circuit, and can avoid the damage caused by the over-discharge of the battery and ensure the safety of the battery pack by finding out the failure of the equalization switch in time while improving the consistency of the battery.
Description
Technical Field
The invention relates to the technical field of battery management systems of electric automobiles, in particular to a passive equalization circuit and a passive equalization method of a battery management system.
Background
In recent years, more and more products adopt lithium ion batteries as main power supplies, mainly because the lithium ion batteries have the advantages of small volume, high energy density, no memory effect, long cycle life, low self-discharge rate and the like; however, the lithium ion battery has high requirements for charging and discharging, and when overcharge, overdischarge, overcurrent, short circuit and the like occur, the pressure and heat of the lithium ion battery are greatly increased, and sparks, combustion and even explosion are easily generated, so that the lithium ion battery is additionally provided with an overcharge and discharge protection circuit without any exception. With the current manufacturing level and process of batteries, the consistency of the batteries cannot be guaranteed. If these batteries are assembled into a module, parameters of the batteries in the module are greatly different due to individual capacity differences generated during the use of the batteries and voltage differences generated by self-discharge rates. In response to this problem, a Battery Management System (BMS) must be equipped with a balancing function to ensure safety and stability. In view of the development of the new energy industry of the electric automobile at present, the passive equalization function is considered to be a reliable method for effectively improving the consistency of the batteries.
The traditional passive equalization circuit adopted by most BMSs in the current industry is shown in FIG. 1, each battery cell B1 is connected in series with an equalization resistor R1 and an equalization switch K1 to form an equalization loop, and the equalization switches are closed to discharge the battery cells. If the equalization switch fails (such as the equalization switch breaks down and is short-circuited), the battery is in an uncontrollable continuous discharge state. This not only does not play the purpose of protection battery, improvement battery uniformity, can cause bigger damage to the battery on the contrary, finally leads to whole battery module life-span, capacity and security performance to reduce.
Disclosure of Invention
The invention aims to provide a passive equalization circuit and a passive equalization method of a battery management system, which can perform passive equalization on a single battery and are convenient for judging whether an equalization switch of the single battery fails or not.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the present invention provides a passive equalization circuit of a battery management system, including a plurality of batteries connected in series, an equalization loop and an acquisition control circuit connected in series with each battery, further including: matching a resistor;
the matching resistor is used for performing differential impedance matching when the acquisition control circuit acquires voltage;
one end of the acquisition control circuit is connected with the first end of each equalization loop, the other end of the acquisition control circuit is connected with the second end of each equalization loop through the matching resistor, the acquisition control circuit is used for controlling the connection or disconnection of each equalization loop, voltage acquisition is carried out, and whether the equalization loops fail or not is identified according to the acquired voltage.
Wherein the equalization loop comprises:
the equalizing resistor and the equalizing switch are used for being connected with each battery in series to form a loop after the equalizing switch is closed, and discharging the batteries;
and two ends of the acquisition control circuit are respectively connected with two ends of the equalization switch.
And the resistance value of the equalizing resistor is equal to that of the matching resistor.
Wherein, the acquisition control circuit is specifically configured to:
and after all the equalizing switches are controlled to be switched off, if the voltage at two ends of any equalizing switch is detected to be 0V, determining that the equalizing switches are invalid.
Wherein, the acquisition control circuit is specifically configured to:
in an initial normal working state, controlling all the equalizing switches to be switched off, and detecting the voltage at two ends of each equalizing switch as a first voltage;
and in a switch detection state, controlling all the equalizing switches to be switched off, detecting the voltage at two ends of each equalizing switch as a second voltage, and if any one of the second voltages is equal to the sum of the first voltage of the battery connected in series with the equalizing switches and the first voltage of the adjacent battery, failing to the equalizing switches corresponding to the adjacent batteries.
In another aspect, the present invention provides a passive equalization method for a battery management system, which is implemented by using the above passive equalization circuit, and includes:
the acquisition control circuit controls the connection or disconnection of the equalization loops, acquires voltage and identifies whether the equalization loops are invalid or not according to the acquired voltage.
The acquisition control circuit controls the connection or disconnection of the equalization loops, acquires voltage, and identifies whether the equalization loops fail according to the acquired voltage, wherein the acquisition control circuit comprises:
the acquisition control circuit controls all the equalizing switches to be switched off;
and if the acquisition control circuit detects that the voltage at two ends of any one of the equalization switches is 0V, determining that the equalization switch fails.
Or, the acquisition control circuit controls the on or off of each equalization loop, performs voltage acquisition, and identifies whether the equalization loop fails according to the acquired voltage includes:
in an initial normal working state, the acquisition control circuit controls all the equalizing switches to be switched off, and detects voltages at two ends of each equalizing switch as first voltages;
in a switch detection state, the acquisition control circuit controls all the equalizing switches to be switched off, and detects voltages at two ends of each equalizing switch as second voltages;
and if the acquisition control circuit detects that any one second voltage is equal to the sum of the first voltage of the battery connected with the equalization switch in series and the first voltage of the adjacent battery, determining that the equalization switch corresponding to the adjacent battery is invalid.
The invention has the beneficial effects that:
the passive equalization circuit provided by the invention can realize passive equalization of the battery by changing the connection mode of the acquisition control circuit and the equalization loop, and can judge whether the equalization switch is invalid or not through the acquisition control circuit, thereby improving the consistency of the battery and ensuring the safety of the battery pack.
Drawings
Fig. 1 is a prior art passive equalization circuit.
Fig. 2 is a passive equalization circuit of a battery management system according to an embodiment of the present invention.
Fig. 3 is a flowchart of a passive balancing method of a battery management system according to a second embodiment of the present invention.
Fig. 4 is a flowchart of a passive balancing method of a battery management system according to a third embodiment of the present invention.
Detailed Description
In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.
Example one
Fig. 2 is a passive equalization circuit of the battery management system provided by the present invention. As shown in fig. 2, the present embodiment provides a passive equalization circuit of a battery management system, which not only can implement passive equalization of batteries, but also can determine whether an equalization switch fails through an acquisition control circuit, where the passive equalization circuit includes a plurality of batteries 13 connected in series, an equalization loop 12 connected in series with each battery, and an acquisition control circuit 11, and further includes: and matching the resistance.
The matching resistor is used for performing differential impedance matching when the acquisition control circuit acquires voltage. Differential impedance matching can effectively eliminate various reflection noises.
One end of the acquisition control circuit 11 is connected to a first end of each equalization loop 12, and the other end is connected to a second end of each equalization loop 12 through the matching resistor, and is used for controlling the conduction or the disconnection of each equalization loop 12, performing voltage acquisition, and identifying whether the equalization loop 12 fails according to the acquired voltage.
As shown in fig. 2, the matching resistance of the battery B1 is R0, and the balancing resistance is R1; the matching resistance of the battery B2 is R1, and the equalizing resistance is R2; the matching resistance of the battery B3 is R2, and the balancing resistance is R3.
Wherein the equalization loop 12 comprises:
and the equalizing resistor and the equalizing switch are used for being connected with each battery in series to form a loop after the equalizing switch is closed, and discharging the batteries. The equalizing resistance of the battery B1 is R1, and the equalizing switch is S1; the equalizing resistance of the battery B2 is R2, and the equalizing switch is S2; the equalizing resistance of the battery B3 is R3, and the equalizing switch is S3.
During voltage acquisition, the matching resistor and the balancing resistor form differential impedance matching, and during passive balancing, the balancing resistor and the balancing switch discharge the corresponding battery.
And two ends of the acquisition control circuit 11 are respectively connected with two ends of the equalization switch.
And the resistance value of the equalizing resistor is equal to that of the matching resistor.
Wherein, the acquisition control circuit is specifically configured to:
and after all the equalizing switches are controlled to be switched off, if the voltage at two ends of any equalizing switch is detected to be 0V, determining that the equalizing switches are invalid.
For example, after all the equalization switches are controlled to be turned off, if the voltage across the equalization switch S1 is detected to be 0V, it is determined that the equalization switch S1 is disabled.
Or, the acquisition control circuit is specifically configured to:
in an initial normal working state, controlling all the equalizing switches to be switched off, and detecting the voltage at two ends of each equalizing switch as a first voltage; and in a switch detection state, controlling all the equalizing switches to be switched off, detecting the voltage at two ends of each equalizing switch as a second voltage, and if any one of the second voltages is equal to the sum of the first voltage of the battery connected in series with the equalizing switches and the first voltage of the adjacent battery, failing to the equalizing switches corresponding to the adjacent batteries.
For example, in an initial normal operating state, all the equalization switches are controlled to be turned off, the voltage across each equalization switch is detected, the voltage across the equalization switch S1 is U1, and the voltage across the equalization switch S2 is U2, which serve as a first voltage; in a switch detection state, controlling all the equalizing switches to be switched off, and detecting the voltage at two ends of each equalizing switch as a second voltage; if the second voltage collected across the equalization switch S2 is equal to the first voltage U2 of the battery B2 connected in series with the equalization switch S2 plus the first voltage U1 of the adjacent battery B1, the equalization switch S1 corresponding to the adjacent battery B1 fails.
The passive equalization circuit provided by the embodiment can realize passive equalization of the battery by changing the connection mode of the acquisition control circuit and the equalization loop, and can judge whether the equalization switch fails or not through the acquisition control circuit, so that the battery consistency is improved, meanwhile, the failure of the equalization switch can be timely found, the damage caused by over-discharge of the battery can be avoided, and the safety of the battery pack is ensured.
Example two
The present embodiment provides a passive equalization method for a battery management system, which is executed by using the passive equalization circuit of the foregoing embodiment, and is used for determining whether an equalization switch fails.
The passive equalization method comprises the following steps:
and S21, the acquisition control circuit controls the connection or disconnection of the equalization loops and acquires voltage.
The acquisition control circuit controls all the equalizing switches to be switched off and performs voltage acquisition.
And S22, identifying whether the equalizing loop is failed according to the collected voltage.
And if the acquisition control circuit detects that the voltage at two ends of any one equalizing switch is 0V, determining that the equalizing switch fails.
The embodiment controls the on-off of the equalization switches through the acquisition control circuit, acquires the voltages at the two ends of each equalization switch to judge whether the equalization switches fail, can timely find out that the equalization switches fail while improving the consistency of the batteries, avoids damage caused by over-discharge of the batteries, and ensures the safety of the battery pack.
EXAMPLE III
The present embodiment provides a passive equalization method for a battery management system, which is executed by using the passive equalization circuit of the foregoing embodiment, and is used for determining whether an equalization switch fails.
The passive equalization method comprises the following steps:
and S31, in the initial normal working state, the acquisition control circuit controls all the equalizing switches to be switched off, and detects the voltage at two ends of each equalizing switch as a first voltage.
And S32, in the switch detection state, the acquisition control circuit controls all the equalization switches to be switched off, and detects the voltage at two ends of each equalization switch as a second voltage.
And S33, judging whether any one second voltage detected by the acquisition control circuit is equal to the first voltage of the battery connected with the equalizing switch in series plus the first voltage of the adjacent battery, if so, executing the step S34, otherwise, not executing any operation.
And S34, determining that the equalization switch corresponding to the adjacent battery is failed.
The embodiment controls the on-off of the equalization switches through the acquisition control circuit, acquires the voltages at the two ends of each equalization switch to judge whether the equalization switches fail, can timely find out that the equalization switches fail while improving the consistency of the batteries, avoids damage caused by over-discharge of the batteries, and ensures the safety of the battery pack.
The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.
Claims (5)
1. The utility model provides a passive equalizer circuit of battery management system, includes the battery of a plurality of series connections, with the equalizer circuit and the acquisition control circuit of every battery series connection which characterized in that still includes: matching a resistor;
the matching resistor is used for performing differential impedance matching when the acquisition control circuit acquires voltage;
the equalizing loop comprises equalizing resistors and equalizing switches, and is used for being connected with each battery in series to form a loop after the equalizing switches are closed so as to discharge the batteries; the resistance value of the equalizing resistor is equal to that of the matching resistor;
the two ends of the acquisition control circuit are respectively connected with the two ends of the equalization switch, and the acquisition control circuit specifically comprises: one end of the acquisition control circuit is connected between the equalizing resistors and the equalizing switches of the equalizing loops, and the other end of the acquisition control circuit is connected with the other end of the equalizing switches of the equalizing loops through the matching resistors and is used for controlling all the equalizing switches to be switched off in an initial normal working state and detecting voltages at two ends of each equalizing switch to serve as first voltages; and in a switch detection state, controlling all the equalizing switches to be switched off, detecting the voltage at two ends of each equalizing switch as a second voltage, and if any one of the second voltages is equal to the sum of the first voltage of the battery connected in series with the equalizing switches and the first voltage of the adjacent battery, failing to the equalizing switches corresponding to the adjacent batteries.
2. The circuit of claim 1, wherein the acquisition control circuit is specifically configured to:
and after all the equalizing switches are controlled to be switched off, if the voltage at two ends of any equalizing switch is detected to be 0V, determining that the equalizing switches are invalid.
3. A passive equalization method for a battery management system, performed using the passive equalization circuit of claim 1, comprising:
the acquisition control circuit controls the connection or disconnection of the equalization loops, acquires voltage and identifies whether the equalization loops are invalid or not according to the acquired voltage.
4. The method of claim 3, wherein the acquisition control circuit controls the on or off of each equalization loop and performs voltage acquisition, and the identifying whether the equalization loop fails according to the acquired voltage comprises:
the acquisition control circuit controls all the equalizing switches to be switched off;
and if the acquisition control circuit detects that the voltage at two ends of any one of the equalization switches is 0V, determining that the equalization switch fails.
5. The method of claim 3, wherein the acquisition control circuit controls the on or off of each equalization loop and performs voltage acquisition, and the identifying whether the equalization loop fails according to the acquired voltage comprises:
in an initial normal working state, the acquisition control circuit controls all the equalizing switches to be switched off, and detects voltages at two ends of each equalizing switch as first voltages;
in a switch detection state, the acquisition control circuit controls all the equalizing switches to be switched off, and detects voltages at two ends of each equalizing switch as second voltages;
and if the acquisition control circuit detects that any one second voltage is equal to the sum of the first voltage of the battery connected with the equalization switch in series and the first voltage of the adjacent battery, determining that the equalization switch corresponding to the adjacent battery is invalid.
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| CN201611241791.2A CN106786922B (en) | 2016-12-29 | 2016-12-29 | Passive equalization circuit and method of battery management system |
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| CN110015130B (en) * | 2017-08-31 | 2021-01-19 | 比亚迪股份有限公司 | Battery equalization system, vehicle, battery equalization method, and storage medium |
| CN108226790B (en) * | 2017-11-30 | 2020-09-01 | 宁德时代新能源科技股份有限公司 | Equalization circuit state detection device and method, battery pack and battery management system |
| CN108263239B (en) * | 2018-02-08 | 2020-03-10 | 北京新能源汽车股份有限公司 | Passive equalization circuit, fault diagnosis method and automobile |
| CN110712562A (en) * | 2019-10-12 | 2020-01-21 | 深圳中科新能源汽车技术有限公司 | Method for improving sampling precision and equalization efficiency during battery equalization |
| CN111564882B (en) * | 2020-05-27 | 2023-06-16 | 国网江西省电力有限公司电力科学研究院 | Gradient utilization power battery equalization method |
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| CN202794479U (en) * | 2012-08-31 | 2013-03-13 | 惠州市亿能电子有限公司 | Failure on-line detection circuit of passive equalization circuit |
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| CN202794479U (en) * | 2012-08-31 | 2013-03-13 | 惠州市亿能电子有限公司 | Failure on-line detection circuit of passive equalization circuit |
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