CN113824182A - Passive equalization method and passive equalization system with self-variable period - Google Patents
Passive equalization method and passive equalization system with self-variable period Download PDFInfo
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- CN113824182A CN113824182A CN202111083903.7A CN202111083903A CN113824182A CN 113824182 A CN113824182 A CN 113824182A CN 202111083903 A CN202111083903 A CN 202111083903A CN 113824182 A CN113824182 A CN 113824182A
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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
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4207—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells for several batteries or cells simultaneously or sequentially
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
- H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
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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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
- H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
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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
Abstract
The invention discloses a self-changing period passive equalization method and a system, when a battery pack is in a discharge state and discharge current is smaller than a current threshold, passive equalization is carried out in a first equalization period; when the battery pack is in a charging state, and the maximum single battery voltage is smaller than a fourth voltage threshold, performing passive equalization in a second equalization period, otherwise, performing passive equalization in a first equalization period; when the battery pack is in a standing state, performing passive equalization in a third equalization period; the equalizing speed of the third equalizing period is greater than that of the second equalizing period, and the equalizing speed of the second equalizing period is greater than that of the first equalizing period. The invention realizes the equalization at the adaptive equalization speed according to different states of the battery pack, and improves the passive equalization effect and the equalization efficiency of the battery pack. And no matter what state the battery pack is, the balance can be started, so that the pressure difference between the single batteries in the standing state is reduced, and the problem that the battery pack cannot be charged due to overlarge pressure difference is solved.
Description
Technical Field
The invention relates to the technical field of battery pack equalization, in particular to a self-variable period passive equalization method and a passive equalization system.
Background
In order to meet the voltage and capacity requirements, in practical applications, the single batteries are usually connected in series to form a large battery pack. When the single batteries in the battery pack are charged and discharged, the situation that a certain single battery reaches a charge-discharge cutoff condition before other single batteries in the charge-discharge process can occur because various electrical and physicochemical indexes of each single battery cannot be guaranteed to be completely consistent.
In order to reduce the difference of each single battery in the battery pack, a passive equalization mode can be adopted. In the prior art, equalization is often performed when the voltage of a single battery at the charging end of a battery pack is high, equalization is stopped after charging is finished, equalization time is short, equalization capacity is small, equalization speed is slow, and the battery pack is not fully equalized. Moreover, if the battery pack is not charged all the time, the voltage difference between the battery cells of the battery pack cannot be eliminated, and an excessive voltage difference may in turn result in the battery pack not being charged.
Chinese patent CN202011224568.3 discloses a method, an apparatus, a device and a storage medium for controlling adaptive equalization of a battery pack, which aims at the application scenario of intermittent charging, i.e. floating charging, of a backup power supply, and realizes adaptive control of passive equalization of the battery pack through at least two charging processes and a complex equalization algorithm, thereby enabling the battery pack to achieve a long-term floating charging state. However, the method is not suitable for application scenarios without floating charge, such as application scenarios of charging batteries of electric automobiles and electric bicycles, and the like, and the application range is limited.
Therefore, it is desirable to provide a new passive equalization method and equalization system to solve the above-mentioned problems in the prior art.
Disclosure of Invention
The invention aims to provide a self-variable period passive equalization method to improve the passive equalization effect of a battery pack.
Another objective of the present invention is to provide a self-varying period passive equalization system to improve the passive equalization effect of the battery pack.
To achieve one of the above objects, the present invention provides a self-varying period passive equalization method, including:
acquiring the voltage of each single battery in the battery pack in real time, and sequencing the voltage of the single batteries;
calculating a difference value between the maximum single battery voltage and the minimum single battery voltage, if the difference value is greater than or equal to a preset first voltage threshold, further judging whether a single battery with a voltage greater than a preset second voltage threshold and less than a preset third voltage threshold exists, if so, selecting equalization channels corresponding to a plurality of single batteries in the single batteries with the voltage greater than the second voltage threshold and less than the third voltage threshold according to the voltage of the single batteries;
acquiring the state of a battery pack, if the battery pack is in a discharging state, judging whether the discharging current of the battery pack is smaller than a preset current threshold, and if so, enabling the selected equalization channel to perform passive equalization in a first equalization period; if the battery pack is in a charging state, judging whether the maximum single battery voltage of the battery pack is smaller than a preset fourth voltage threshold, if so, enabling the selected equalization channel to perform passive equalization in a second equalization period, wherein the equalization speed of the second equalization period is larger than that of the first equalization period, and if not, enabling the selected equalization channel to perform passive equalization in the first equalization period; and if the battery pack is in a standing state, passively equalizing the selected equalization channel in a third equalization period, wherein the equalization speed of the third equalization period is greater than that of the second equalization period.
Preferably, the "selecting, according to the voltage of the single battery, the equalization channels corresponding to the plurality of single batteries in the single batteries which are greater than the second voltage threshold and smaller than the third voltage threshold" is: and selecting the equalization channels corresponding to the single batteries with the maximum voltage in the single batteries which are larger than the second voltage threshold and smaller than the third voltage threshold so as to simultaneously start the equalization channels for passive equalization.
Preferably, the "acquiring the state of the battery pack" is: acquiring the current value and the current direction of the battery pack, and if the current value is continuously zero, determining that the battery pack is in a standing state; and if the current value is continuously larger than zero, judging that the battery pack is in a discharging state or a charging state according to the current direction.
In order to achieve the second purpose, the invention provides a self-changing period passive equalization system, which comprises a passive equalization unit, an analog front end unit, a communication unit, a charge and discharge signal acquisition unit and a control unit, wherein the passive equalization unit is electrically connected with the analog front end unit, the communication unit is electrically connected with the analog front end unit and the control unit, and the charge and discharge signal acquisition unit is electrically connected with the control unit. The passive equalization unit comprises a plurality of equalization channels, and each equalization channel corresponds to a single battery. The simulation front end unit is used for collecting the voltage and the charging and discharging current of the single battery of the battery pack and sending the voltage and the charging and discharging current to the control unit through the communication unit. The charge and discharge signal acquisition unit is used for acquiring the state information of the battery pack. The control unit is configured to: and if the difference value is larger than or equal to a preset first voltage threshold value, further judging whether a single battery with the voltage larger than a preset second voltage threshold value and smaller than a preset third voltage threshold value exists, and if so, selecting equalization channels corresponding to a plurality of single batteries in the single batteries larger than the second voltage threshold value and smaller than the third voltage threshold value according to the voltage of the single batteries. Then, receiving state information of the battery pack, if the battery pack is in a discharging state, judging whether the discharging current of the battery pack is smaller than a preset current threshold, if so, sending a control instruction to the analog front-end unit to control the selected equalization channel to perform passive equalization in a first equalization period; if the battery pack is in a charging state, judging whether the maximum single battery voltage of the battery pack is smaller than a preset fourth voltage threshold, if so, controlling the selected equalization channel to perform passive equalization in a second equalization period, wherein the equalization speed of the second equalization period is larger than that of the first equalization period, and if not, controlling the selected equalization channel to perform passive equalization in the first equalization period; and if the battery pack is in a standing state, controlling the selected equalization channel to perform passive equalization in a third equalization period, wherein the equalization speed of the third equalization period is greater than that of the second equalization period.
Preferably, the "selecting, according to the voltage of the single battery, the equalization channels corresponding to the plurality of single batteries in the single batteries which are greater than the second voltage threshold and smaller than the third voltage threshold" is to select the equalization channels corresponding to the plurality of single batteries with the maximum voltage in the single batteries which are greater than the second voltage threshold and smaller than the third voltage threshold, and the control unit controls the plurality of equalization channels to be simultaneously turned on for passive equalization.
Preferably, the "acquiring the state of the battery pack" is: acquiring the current value and the current direction of the battery pack, and if the current value is continuously zero, determining that the battery pack is in a standing state; and if the current value is continuously larger than zero, judging that the battery pack is in a discharging state or a charging state according to the current direction.
Preferably, the passive equalization system further includes an external communication unit, and the external communication unit is electrically connected to the control unit and is configured to output the operating state information of the passive equalization system and receive parameter configuration.
Compared with the prior art, the method and the device have the advantages that the passive equalization period is automatically changed according to different states of the battery pack by identifying the state of the battery pack, the equalization is carried out at the adaptive passive equalization speed according to the different states of the battery pack, and the passive equalization effect and the equalization efficiency of the battery pack are improved. The passive equalization method can start passive equalization no matter the battery pack is in a charging state, a discharging state or a standing state, reduces the voltage difference value between the single batteries of the battery pack in the standing state, solves the problem that the battery pack cannot be charged due to overlarge voltage difference value, enlarges the usability, and ensures that the battery pack keeps good consistency in the whole life service cycle.
Drawings
Fig. 1 is a flowchart of a self-varying period passive equalization method according to an embodiment of the present invention.
Fig. 2 is a schematic diagram illustrating the principle of passively equalizing the self-varying period according to an embodiment of the present invention.
Fig. 3 is a block diagram of the structure of the self-varying period passive equalization system according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of a partial structure of a self-varying period passive equalization system according to an embodiment of the present invention.
Detailed Description
In order to explain the contents, structural features, objects and effects of the present invention in detail, the technical solutions 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, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, the self-varying period passive equalization method provided in the embodiment shown in fig. 1 includes the steps of:
and S1, acquiring the voltage of each single battery in the battery pack in real time, and sequencing the voltage of the single batteries.
S2, calculating a difference between the maximum cell voltage and the minimum cell voltage, and if the difference is greater than or equal to a preset first voltage threshold V1 (usually taking a value of 30mV to 100mV, in this embodiment, the first voltage threshold V1 is 30mV), it indicates that passive equalization needs to be started to reduce the voltage difference between the cells, and therefore, the process proceeds to step S3. If the difference is smaller than the first voltage threshold V1, it indicates that passive equalization is not needed, and at this time, if the current state is in a passive equalization state, the passive equalization is stopped; if the passive equalization is not started, the method returns to step S1 to continue polling the cell voltages.
S3, determining whether there is a cell with a voltage greater than a preset second voltage threshold V2 (3V in this embodiment) and less than a preset third voltage threshold V3 (4V in this embodiment), if yes, selecting equalization channels corresponding to a plurality of cells greater than the second voltage threshold V2 and less than the third voltage threshold V3 according to the cell voltage sorting result, and proceeding to step S4. If the voltage of the single battery is not larger than the second voltage threshold V2 and smaller than the third voltage threshold V3, the passive equalization is not allowed to be performed, and at the moment, if the single battery is currently in a passive equalization state, the passive equalization is stopped; if the passive equalization is not started, the method returns to step S1 to continue polling the cell voltages. By setting the voltage greater than the second voltage threshold V2 and less than the third voltage threshold V3, the equalization switch of the equalization channel is ensured to be switched on and off safely and reliably.
S4, obtaining a state of the battery pack, and if the battery pack is in a discharging state, further determining whether a discharging current of the battery pack is smaller than a preset current threshold I (5A in this embodiment) to avoid misdetermination caused by a voltage transient response being fast and a voltage acquisition speed being delayed during a rapid large current change process. And if the discharge current of the battery pack is smaller than the current threshold I, the voltage change is more smooth, so that the selected equalization channel performs passive equalization in a first equalization period. If the discharge current of the battery pack is not less than the current threshold I, passive equalization is not suitable. Stopping passive equalization if the current state is in a passive equalization state; if the battery pack is not in the state of starting passive equalization currently, the method returns to the step S1 to continue polling the voltages of the single batteries. If the battery pack is in a charging state, it is further determined whether the maximum cell voltage of the battery pack is less than a preset fourth voltage threshold V4 (3.6V in this embodiment). If yes, the selected equalization channel is enabled to perform passive equalization in a second equalization period, the equalization speed of the second equalization period is larger than that of the first equalization period, and if not, the selected equalization channel is enabled to perform passive equalization in the first equalization period. Therefore, the equalizing speed is guaranteed and the battery is prevented from being overcharged, and generally, the fourth voltage threshold V4+50mV is an overcharge protection value. If the battery pack is in a standing state, the current is zero when the battery pack stands, the voltage change is the most stable, and the maximum equalization speed can be selected for passive equalization, so that the selected equalization channel is passively equalized in a third equalization period, and the equalization speed of the third equalization period is greater than the equalization speeds of the second equalization period and the first equalization period.
In this embodiment, in step S3, the equalization channels corresponding to the multiple cells with the largest voltage among the cells larger than the second voltage threshold V2 and smaller than the third voltage threshold V3 are selected, for example, in a battery pack composed of 20 strings of lithium iron phosphate cells, the voltages of 6 cells meet the requirement that the voltages of the cells are larger than the second voltage threshold V2 and smaller than the third voltage threshold V3, in this embodiment, the equalization channels corresponding to the 4 cells with the largest voltage among the 6 cells are selected, and in step S4, the 4 equalization channels are simultaneously turned on for passive equalization. Therefore, the passive equalization effect and the equalization efficiency which are better can be achieved, and the over-high temperature of the battery pack caused by the fact that too many single batteries are subjected to passive equalization simultaneously can be avoided. Of course, in other embodiments, the equalization channels corresponding to all the cells meeting the condition of being greater than the second voltage threshold V2 and less than the third voltage threshold V3 may be simultaneously turned on for passive equalization.
It is understood that the set second voltage threshold V2, third voltage threshold V3, and fourth voltage threshold V4 are necessarily greater than the minimum cell voltage. The specific values of the first voltage threshold V1, the second voltage threshold V2, the third voltage threshold V3 and the fourth voltage threshold V4 are flexibly set according to specific situations, and are not limited to a specific value.
In this embodiment, in step S4, "acquiring the state of the battery pack" is: acquiring the current value and the current direction of the battery pack, and if the current value is continuously zero, determining that the battery pack is in a standing state; if the current value is continuously larger than zero, the current direction is continuously positive, and the battery pack is judged to be in a discharge state; if the current value is continuously larger than zero, the current direction is continuously negative, and the battery pack is determined to be in a charging state. Of course, the state of the battery pack may also be obtained in other manners, for example, in an embodiment, the state is determined to be in a discharging state by obtaining a discharging key signal and an auxiliary source signal of the power supply, and if the key signal is obtained; if the auxiliary source signal is acquired, judging that the battery pack is in a charging state; and if the key signal and the auxiliary source signal are not acquired, determining that the battery pack is in a static state.
Referring next to fig. 2, fig. 2 illustrates a schematic diagram of a passive equalization autochange period. As shown in fig. 2, the total equalization period is set to T, which is composed of two major portions, T1 and T2. The time for stopping equalizing the scanning voltage and current (equalizing stopping time) is T1, the time for recovering equalizing and reading the voltage information and current information of the single battery (equalizing time) is T2, and T2 is more than or equal to T1. The size of T1 is usually determined by the hardware design circuit, such as the scan speed of the analog front-end chip, and T1 is varied from 10mS to 50 mS. T2 may be dynamically adjusted according to the response requirements of the passive equalization system. Taking this embodiment as an example, since the current changes violently in the discharging process, the voltage change speed is fast, and the response speed for acquisition is fast, the total equalization period T is required to be small, and thus the T2 is also required to be small. In the constant-current charging stage of the charging state, the voltage variation value fluctuation is small, and the requirement on the response speed of acquisition is not high, so that the time of T2 can be properly prolonged, the passive equalization time is prolonged, and the equalization speed is accelerated. The rest state may further extend the time of T2 compared to the charge state, thereby maximizing the passive equalization speed.
For example, let the power difference Q between the battery cells be 200mAh, and the maximum passive equalization current IB be 100 mA. The passive equalization in the discharged state takes a first equalization period, the stop equalization time T1 takes 30mS, the equalization time T2 takes 30mS, the total equalization period (first equalization period) T takes 60mS, the equalization time T1 takes (Q/(IB T2/T) takes (200mAh/(100mA 30mS/60mS) 4 h.) when the passive equalization in the charged state takes a second equalization period, the stop equalization time T1 takes 30mS, the equalization time T2 takes 120mS, the total equalization period (second equalization period) T150 mS, the equalization time T1 takes (Q/(IB T2/T) takes (200 h/(100mA 120mS/150mS) 2.5 h.) when the passive equalization in the charged state takes a second equalization period, the stop equalization time T5636 takes a third equalization period, the stop equalization time T1 takes a third equalization period, the stop equalization time T3560 mS) takes a third equalization period, the stop equalization time T3560 mS (200 h, the total equalization time T3560 mS) takes a third equalization period, the third equalization period (3560 mS) takes a third equalization period, the equalization time T1 is (Q/(IB × T2/T) ≦ 2.23h, (200mAh/(100mA × 270mS/300mS) ≦ 2.23 h), that is, the third equalization period > the second equalization period > the first equalization period, and the equalization speed is, that is, the third equalization period > the second equalization period > the first equalization period.
Referring to fig. 3, as shown in fig. 3, the self-varying period passive equalization system 100 includes a passive equalization unit 10, an analog front end unit 20, a communication unit 30, a charge and discharge signal acquisition unit 40, and a control unit 50, wherein the passive equalization unit 10 is electrically connected to the analog front end unit 20, the communication unit 30 is electrically connected to the analog front end unit 20 and the control unit 50, and the charge and discharge signal acquisition unit 40 is electrically connected to the control unit 50. The passive equalization unit 10 includes a plurality of equalization channels, and each equalization channel corresponds to a single battery. The analog front end unit 20 is configured to collect cell voltages and charging/discharging currents of the battery pack and send the collected voltages and charging/discharging currents to the control unit 50 through the communication unit 30. The charge and discharge signal acquisition unit 40 is used to acquire the state information of the battery pack. The control unit 50 is configured to: sorting the voltages of the single batteries, calculating a difference value between the maximum voltage of the single batteries and the minimum voltage of the single batteries, if the difference value is greater than or equal to a preset first voltage threshold value V1, further judging whether the single batteries with the voltages greater than a preset second voltage threshold value V2 and less than a preset third voltage threshold value V3 exist, and if yes, selecting equalization channels corresponding to a plurality of single batteries in the single batteries greater than the second voltage threshold value V2 and less than the third voltage threshold value V3 according to the voltages of the single batteries. Then, receiving state information of the battery pack, if the battery pack is in a discharging state, judging whether the discharging current of the battery pack is smaller than a preset current threshold I, if so, sending a control instruction to the analog front end unit 20 to control the selected equalization channel to perform passive equalization in a first equalization period; if the battery pack is in a charging state, judging whether the maximum single battery voltage of the battery pack is smaller than a preset fourth voltage threshold value V4, if so, controlling the selected equalization channel to perform passive equalization in a second equalization period, wherein the equalization speed of the second equalization period is larger than that of the first equalization period, and if not, controlling the selected equalization channel to perform passive equalization in the first equalization period; and if the battery pack is in a standing state, controlling the selected equalization channel to perform passive equalization in a third equalization period, wherein the equalization speed of the third equalization period is greater than that of the second equalization period.
Further, the passive equalization system 100 further includes an external communication unit 60, and the external communication unit 60 is electrically connected to the control unit 50, and is configured to output the operating status information of the passive equalization system 100 and receive the parameter configuration. Specifically, the parameter configuration may be fixed in the control unit 50, and the external communication unit 60 is configured to modify the configuration, so as to modify the appropriate parameters according to different battery types. Meanwhile, the working state information of the passive equalization system 100 is output through the external communication unit 60, so that the working state of the passive equalization system 100 is conveniently acquired.
The communication unit 30 is a digital isolation communication unit. The external communication unit 60 is a CAN communication unit or an RS485 communication unit. Specific values of each voltage threshold and current threshold, selection of an equalization channel, a specific acquisition mode of a state of the battery pack, a principle of a passive equalization self-changing period, and the like are described in the description of the passive equalization method, and are not described herein again.
Referring next to fig. 4, fig. 4 shows the passive equalizing unit 10, some of the constituent elements of the analog front-end unit 20, and two of the battery cells B1, B2 of the battery pack. As shown in fig. 4, one of the equalizing channels of the passive equalizing unit 10 includes an equalizing switch Q1, an equalizing resistor Rbal, and some auxiliary components, such as a resistor Rn, a resistor Rbn, a capacitor Cn, a zener diode Dbase, and the like, where the equalizing resistor Rbal is electrically connected to a single battery B1. When passive equalization is required, the analog front-end unit 20 controls the conduction of the equalization switch Q1 to enable the corresponding equalization resistor Rbal to consume the electric energy of the corresponding single battery B1, thereby realizing equalization; when passive equalization is not required, the analog front end unit 20 controls the equalization switch Q1 to be turned off to stop passive equalization.
In conclusion, the passive equalization method and the battery pack can automatically change the passive equalization period according to different states of the battery pack by identifying the state of the battery pack, realize equalization at an adaptive passive equalization speed according to different states of the battery pack, and improve the passive equalization effect and the equalization efficiency of the battery pack. The passive equalization method can start passive equalization no matter the battery pack is in a charging state, a discharging state or a standing state, reduces the voltage difference value between the single batteries of the battery pack in the standing state, solves the problem that the battery pack cannot be charged due to overlarge voltage difference value, enlarges the usability, and ensures that the battery pack keeps good consistency in the whole life service cycle.
The above disclosure is only a preferred embodiment of the present invention, and should not be taken as limiting the scope of the invention, so that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Claims (7)
1. A method for passive equalization with self-varying period, comprising:
acquiring the voltage of each single battery in the battery pack in real time, and sequencing the voltage of the single batteries;
calculating a difference value between the maximum single battery voltage and the minimum single battery voltage, if the difference value is greater than or equal to a preset first voltage threshold, further judging whether a single battery with a voltage greater than a preset second voltage threshold and less than a preset third voltage threshold exists, if so, selecting equalization channels corresponding to a plurality of single batteries in the single batteries with the voltage greater than the second voltage threshold and less than the third voltage threshold according to the voltage of the single batteries;
acquiring the state of a battery pack, if the battery pack is in a discharging state, judging whether the discharging current of the battery pack is smaller than a preset current threshold, and if so, enabling the selected equalization channel to perform passive equalization in a first equalization period; if the battery pack is in a charging state, judging whether the maximum single battery voltage of the battery pack is smaller than a preset fourth voltage threshold, if so, enabling the selected equalization channel to perform passive equalization in a second equalization period, wherein the equalization speed of the second equalization period is larger than that of the first equalization period, and if not, enabling the selected equalization channel to perform passive equalization in the first equalization period; and if the battery pack is in a standing state, passively equalizing the selected equalization channel in a third equalization period, wherein the equalization speed of the third equalization period is greater than that of the second equalization period.
2. The passive equalization method according to claim 1, wherein the selecting equalization channels corresponding to a plurality of the single batteries which are larger than the second voltage threshold and smaller than the third voltage threshold according to the voltage of the single batteries is: and selecting the equalization channels corresponding to the single batteries with the maximum voltage in the single batteries which are larger than the second voltage threshold and smaller than the third voltage threshold so as to simultaneously start the equalization channels for passive equalization.
3. The passive equalization method according to claim 1, wherein said "acquiring the state of the battery pack" is: acquiring the current value and the current direction of the battery pack, and if the current value is continuously zero, determining that the battery pack is in a standing state; and if the current value is continuously larger than zero, judging that the battery pack is in a discharging state or a charging state according to the current direction.
4. The utility model provides a from passive balanced system of variable cycle, its characterized in that, includes passive balanced unit, simulation front end unit, communication unit, charge-discharge signal acquisition unit and the control unit, passive balanced unit is connected with simulation front end unit electricity, communication unit with simulation front end unit, the control unit electricity are connected, charge-discharge signal acquisition unit with the control unit electricity is connected, passive balanced unit is including a plurality of balanced passageways, each balanced passageway corresponds a battery cell, simulation front end unit is used for gathering the battery cell voltage of group battery, charge-discharge current and passes through communication unit sends to the control unit, charge-discharge signal acquisition unit is used for acquireing the state information of group battery, the control unit is configured to: sorting the voltages of the single batteries in size, calculating a difference value between the maximum voltage of the single batteries and the minimum voltage of the single batteries, if the difference value is greater than or equal to a preset first voltage threshold, further judging whether the single batteries with the voltages greater than a preset second voltage threshold and less than a preset third voltage threshold exist, if so, selecting equalization channels corresponding to a plurality of single batteries in the single batteries with the voltages greater than the second voltage threshold and less than the third voltage threshold according to the voltages of the single batteries; receiving state information of a battery pack, if the battery pack is in a discharging state, judging whether the discharging current of the battery pack is smaller than a preset current threshold value, if so, sending a control instruction to the analog front-end unit to control a selected equalization channel to perform passive equalization in a first equalization period; if the battery pack is in a charging state, judging whether the maximum single battery voltage of the battery pack is smaller than a preset fourth voltage threshold, if so, controlling the selected equalization channel to perform passive equalization in a second equalization period, wherein the equalization speed of the second equalization period is larger than that of the first equalization period, and if not, controlling the selected equalization channel to perform passive equalization in the first equalization period; and if the battery pack is in a standing state, controlling the selected equalization channel to perform passive equalization in a third equalization period, wherein the equalization speed of the third equalization period is greater than that of the second equalization period.
5. The passive equalization system according to claim 4, wherein the selecting equalization channels corresponding to a plurality of single batteries that are larger than the second voltage threshold and smaller than the third voltage threshold according to the voltage of the single batteries is selecting equalization channels corresponding to a plurality of single batteries that have the highest voltage among the single batteries that are larger than the second voltage threshold and smaller than the third voltage threshold, and the control unit controls the plurality of equalization channels to be simultaneously turned on for passive equalization.
6. The passive equalization system of claim 4, wherein the "obtaining the state of the battery pack" is: acquiring the current value and the current direction of the battery pack, and if the current value is continuously zero, determining that the battery pack is in a standing state; and if the current value is continuously larger than zero, judging that the battery pack is in a discharging state or a charging state according to the current direction.
7. The passive equalization system of claim 4, further comprising an external communication unit electrically connected to the control unit for outputting operational status information of the passive equalization system and receiving parameter configurations.
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| WO2023230937A1 (en) * | 2022-05-31 | 2023-12-07 | 北京小米移动软件有限公司 | Battery balancing circuit and battery balancing method |
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| CN112491109A (en) * | 2020-11-05 | 2021-03-12 | 上海航天电源技术有限责任公司 | Adaptive equalization control method, device and equipment for battery pack and storage medium |
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| CN102111005A (en) * | 2011-03-08 | 2011-06-29 | 上海大学 | Equalization management system and method for nondestructive lithium battery |
| CN103066650A (en) * | 2012-12-18 | 2013-04-24 | 上海电机学院 | Pitch control system backup battery on-line monitoring and voltage sharing system and method |
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