CN110015129B - Battery equalization method, system, vehicle, storage medium and electronic device - Google Patents

Battery equalization method, system, vehicle, storage medium and electronic device Download PDF

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Publication number
CN110015129B
CN110015129B CN201710776101.1A CN201710776101A CN110015129B CN 110015129 B CN110015129 B CN 110015129B CN 201710776101 A CN201710776101 A CN 201710776101A CN 110015129 B CN110015129 B CN 110015129B
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battery
self
equalization
single battery
discharge rate
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CN110015129A (en
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罗红斌
王超
沈晓峰
曾求勇
刘苑红
张祥
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BYD Co Ltd
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BYD Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60LPROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60LPROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B60L58/21Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules having the same nominal voltage
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60LPROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B60L58/22Balancing the charge of battery modules
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014Circuits for equalisation of charge between batteries
    • H02J7/0019Circuits for equalisation of charge between batteries using switched or multiplexed charge circuits
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60LPROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00Control parameters of input or output; Target parameters
    • B60L2240/40Drive Train control parameters
    • B60L2240/54Drive Train control parameters related to batteries
    • B60L2240/547Voltage
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/70Energy storage systems for electromobility, e.g. batteries

Abstract

The present disclosure relates to a battery equalization method, a system, a vehicle, a storage medium, and an electronic device, the method comprising: acquiring the self-discharge rate of a single battery to be balanced in a battery pack; acquiring a reference self-discharge rate required by equalization; determining the target equalization duration of the single battery to be equalized according to the self-discharge rate of the single battery to be equalized and the reference self-discharge rate; and controlling the balance of the single battery to be balanced according to the target balancing duration. The target equalization time length based on the equalization process is calculated according to the difference value between the self-discharge rate and the reference self-discharge rate of the single battery to be equalized, so that the equalization process is more accurate, and the situation that the equalization time length is too long or too short is avoided.

Description

Battery equalization method, system, vehicle, storage medium and electronic device
Technical Field
The present disclosure relates to the field of control technologies, and in particular, to a battery equalization method, a battery equalization system, a vehicle, a storage medium, and an electronic device.
Background
A large-capacity battery that provides power energy for an electric vehicle is often referred to as a power battery. The vehicle power battery is generally formed by connecting a plurality of single batteries in series to form a module. With the use of batteries, the difference between the single batteries is gradually enlarged, the consistency between the single batteries is poor, the capacity of the battery pack is limited due to the short plate effect of the batteries, the capacity of the battery pack cannot be fully exerted, and the whole capacity of the battery pack is reduced. On the other hand, the gradual expansion of the difference between the single batteries may cause overcharge of some single batteries, over-discharge of some single batteries, affect the service life of the batteries, damage the batteries, and generate a large amount of heat to cause combustion or explosion of the batteries.
Therefore, the method has very important significance for effectively and uniformly managing the power batteries of the electric automobile, being beneficial to improving the consistency of the batteries in the battery pack, reducing the capacity loss of the batteries, and prolonging the service life of the batteries and the driving range of the electric automobile.
At present, balancing management is performed on a battery pack, battery information of each single battery in the battery pack is usually acquired in real time, whether the single battery needs balancing or not is determined according to the acquired battery information, and when the single battery needs balancing, the single battery needing balancing is balanced. In the process of balancing the single batteries, if the balancing time of the single batteries is too long, the inconsistency of each single battery in the battery pack where the single batteries are located is increased, and the balancing efficiency is low; if the equalization time of the single battery is too short, the equalization effect cannot be achieved. Therefore, how to accurately determine the balancing time of the single battery needing balancing is a problem to be solved.
Disclosure of Invention
The purpose of the present disclosure is to provide a battery equalization method, system, vehicle, storage medium, and electronic device to optimize a battery equalization process.
In order to achieve the above object, a first aspect of the present disclosure provides a battery equalization method, including:
acquiring the self-discharge rate of a single battery to be balanced in a battery pack;
acquiring a reference self-discharge rate required by equalization;
determining the target equalization duration of the single battery to be equalized according to the self-discharge rate of the single battery to be equalized and the reference self-discharge rate;
and controlling the balance of the single battery to be balanced according to the target balancing duration.
A second aspect of the present disclosure provides a battery equalization system, including:
a balancing module, an acquisition module and a control module,
the acquisition module is used for: acquiring the self-discharge rate of a single battery to be balanced in a battery pack;
the control module is used for: acquiring a reference self-discharge rate required by balancing, and determining a target balancing time length of the single battery to be balanced according to the self-discharge rate of the single battery to be balanced and the reference self-discharge rate;
the equalization module is configured to: and balancing the single batteries to be balanced according to the target balancing duration.
A third aspect of the present disclosure provides a computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the method of the first aspect of the present disclosure.
A fourth aspect of the present disclosure provides an electronic device, comprising:
a computer-readable storage medium according to a third aspect of the disclosure; and
one or more processors to execute the program in the computer-readable storage medium.
A fifth aspect of the present disclosure provides a vehicle including: a battery pack and a battery equalization system according to the second aspect of the present disclosure.
Through the technical scheme, the target equalization time length of the single battery to be equalized is determined according to the self-discharge rate and the reference self-discharge rate of the single battery to be equalized in the battery pack, and then the single battery to be equalized is equalized according to the determined target equalization time length. The target equalization time length based on the equalization process is calculated according to the difference value between the self-discharge rate and the reference self-discharge rate of the single battery to be equalized, so that the equalization process is more accurate, and the situation that the equalization time length is too long or too short is avoided.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
fig. 1 is a schematic diagram of a battery equalization system according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of a battery equalization system in which two single batteries share one equalization module according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a battery equalization system of another embodiment of the present disclosure;
fig. 4 is a schematic diagram of a battery equalization system in which two single batteries share one equalization module according to another embodiment of the present disclosure;
fig. 5 is a schematic flow chart of a battery equalization method according to an embodiment of the present disclosure;
fig. 6 is a schematic diagram of an equalization module according to an embodiment of the present disclosure.
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
Referring to fig. 1, a schematic diagram of a battery equalization system according to an embodiment of the present disclosure is shown. This battery equalizing system includes: the system comprises a control module 101, an acquisition module 102, an equalization module 103 and a battery pack 104.
In one embodiment, each cell corresponds to one acquisition module 102 and one equalization module 103. The acquisition module 102 and the equalization module 103 corresponding to the same single battery are respectively connected with the control module 101 through different control channels. The control module can comprise a control chip, the control chip is respectively connected with the acquisition module and the balance module corresponding to the same single battery through two pins, and the two pins correspond to the two channels one by one.
In this embodiment, the control module 101 controls the acquisition module 102 and the equalization module 103 to conduct in a time-sharing manner according to a unit cycle, and respectively performs acquisition of battery information and equalization of a battery, so that the acquisition of the battery information and the equalization are performed in a time-sharing manner. The influence of the equalizing current on the accuracy of battery information acquisition is avoided when the battery information acquisition and the equalization are simultaneously carried out.
In one embodiment, referring to fig. 1, each of the cells is connected to an acquisition module 102 and an equalization module 103, respectively. If the battery pack includes N single batteries, the number of the acquisition modules 102 is N, and the number of the equalization modules 103 is N, so that the control module 101 is connected to the N acquisition modules and the N equalization modules through 2 × N control channels, respectively.
In other embodiments, different cells may share an equalization module, for example, N cells in a battery pack, the same equalization module may be shared, or one equalization module may be shared for each predetermined number (e.g., 2, 3, or 5, etc.) of cells, and so on. When at least two single batteries in the multiple single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in the at least two single batteries needing to be balanced in the balancing time interval of the unit cycle.
Referring to fig. 2, two single batteries share one balancing module, and when two single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in a balancing period of a unit cycle. The alternate connection may be a connection that alternates according to a certain period. For example, referring to fig. 2, when the parallel switch 150 on the parallel branch 15 corresponding to one of the two single batteries 111 is closed for 2s under the control of the control module 14, the parallel switch 150 on the parallel branch 15 corresponding to the other of the two single batteries 111 is opened for 2s under the control of the control module 14. That is, the parallel switch 150 on the parallel branch 15 corresponding to each of the two single batteries 111 is switched from the closed state to the open state or from the open state to the closed state every two seconds in the equalization period. Therefore, on the basis of time-sharing conduction of the acquisition module and the equalization module, the single batteries sharing the same equalization module are alternately connected with the shared equalization module during the equalization time period, and equalization is realized.
Fig. 3 is a schematic structural diagram of a battery equalization system according to another embodiment of the present disclosure.
This battery equalizing system includes: a control module 301, an acquisition module 302, an equalization module 303, and a battery pack 304. The battery pack 304 includes a plurality of unit cells connected in series. The control module 301 is connected to the acquisition module 302 and the equalization module 303 corresponding to the same cell via a control channel 305. The control module is used for controlling the connection of the control module and the corresponding sampling module when the single battery connected with the control module is determined not to need balancing; or, the control module is further configured to multiplex the channels 305 in time division according to a unit period by the acquisition module and the equalization module when it is determined that the single battery connected to the control module needs equalization.
One unit period includes: an acquisition period and an equalization period. The control module 301 controls the acquisition module 302 to sample the battery information of the single battery in an acquisition time period to obtain the battery information of the single battery. The battery information includes at least one of: voltage, current, temperature, etc. In one embodiment, the battery information may include only the voltage value, and thus, the voltage performance parameter of the unit battery may be obtained. In another embodiment, the battery information may also include a voltage value, a current value, a temperature value, and the like, so as to obtain performance parameters such as SOC, internal resistance, self-discharge rate, and the like of the single battery.
The control module 301 determines the single battery to be balanced, which needs to be balanced, according to the battery information of the single battery acquired by the acquisition module 302. For the single battery to be equalized which needs to be started, the control module 301 controls the equalization module corresponding to the single battery to be equalized, and equalizes the single battery to be equalized in an equalization time period.
Therefore, in the embodiment of the disclosure, the acquisition module and the balancing module share the same control channel, the control module controls the acquisition module and the balancing module, and the control channel is multiplexed in time according to a unit period, so that the influence of balancing current on the accuracy of battery information acquisition is avoided when the battery information acquisition and the balancing are performed simultaneously; on the other hand, compared with the embodiment shown in fig. 1, the requirement for the number of channels of the control module chip is reduced, and the hardware cost can be saved.
In one embodiment, a switch K is disposed in a control channel shared by the acquisition module and the equalization module, and the control module 301 is connected to the switch K and is connected to the acquisition module 302 or the equalization module 303 in a time-sharing manner by controlling the switch K. When the switch K is connected with the acquisition module 302, the control module 301 controls the acquisition module 302 to acquire battery information of the single battery in an acquisition period; when the switch K is connected to the balancing module 303, the control module 301 controls the balancing module 303 to balance the corresponding single battery.
In one embodiment, referring to fig. 1, each cell of the battery is connected to an acquisition module 302 and an equalization module 303, respectively. If the battery pack includes N single batteries, the number of the acquisition modules 302 is N, and the number of the equalization modules 303 is N, so that the control module 301 is connected to the acquisition modules and the equalization modules through N control channels.
In other embodiments, different cells may share an equalization module, for example, N cells in a battery pack, the same equalization module may be shared, or one equalization module may be shared for each predetermined number (e.g., 2, 3, or 5, etc.) of cells, and so on. When at least two single batteries in the multiple single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in the at least two single batteries needing to be balanced in the balancing time interval of the unit cycle.
Referring to fig. 4, an exemplary schematic diagram of two unit cells sharing one balancing module is shown. When two single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected with each single battery in the balancing time interval of the unit cycle. The alternate connection may be a connection that alternates according to a certain period. Therefore, on the basis of time-sharing conduction of the acquisition module and the equalization module, the single batteries sharing the same equalization module are alternately connected with the shared equalization module during the equalization time period, and equalization is realized.
In one embodiment, the collecting module may be a voltage collecting chip for collecting the voltage of the single battery during the collecting period.
Referring to fig. 5, based on the battery balancing system shown in any one of the embodiments of fig. 1, fig. 2, fig. 3, or fig. 4, the battery balancing method according to an embodiment of the present disclosure includes:
in step S51, obtaining the self-discharge rate of the single battery to be equalized in the battery pack;
in step S52, a reference self-discharge rate required for equalization is acquired;
in step S53, determining a target equalization duration of the single battery to be equalized according to the self-discharge rate of the single battery to be equalized and the reference self-discharge rate;
in step S54, balancing of the single battery to be balanced is controlled according to the target balancing duration.
The self-discharge rate of the single battery is used for representing the capacity loss condition and the capacity loss rate of the single battery. In one embodiment, when the battery pack stops working and reaches a stable state (time t 1), detecting and recording the open-circuit voltage value V1 of each single battery of the power battery pack; when the battery pack starts to work again (time t2), detecting and recording the open-circuit voltage value V2 of each single battery of the power battery pack; and calculating the self-discharge rate eta of each single battery according to the open-circuit voltage value of each single battery obtained by the two detections.
In one embodiment, the step S51 includes the following steps:
after the battery pack is powered off, determining a first time when each single battery in the battery pack reaches a stable state and a first open-circuit voltage value corresponding to the single battery at the first time;
when the battery pack is electrified again, determining a second time when the single battery is electrified and a second open-circuit voltage value of the single battery at the second time for each single battery in the battery pack;
and determining the self-discharge rate of the single battery according to the first open-circuit voltage value and the second open-circuit voltage value corresponding to the single battery and the duration between the first moment and the second moment corresponding to the single battery.
After the battery pack is powered off, determining a first moment when each single battery in the battery pack reaches a stable state and a first open-circuit voltage value corresponding to the single battery at the first moment.
Stopping working after the battery pack is powered off, and detecting and recording a first moment t when each single battery in the battery pack reaches a stable state when the battery pack reaches the stable state1And the open circuit voltage value V of the single battery1
When the battery pack is powered on again, for each single battery in the battery pack, determining a second time when the single battery is powered on and a second open-circuit voltage value of the single battery at the second time.
And starting to work again when the battery pack is electrified again, and detecting and recording a second moment t of electrifying the single battery for each single battery in the battery pack2And a second open circuit voltage value V at that time2
And determining the ratio of the voltage difference value to the time length as the self-discharge rate of the single battery according to the first open-circuit voltage value and the second open-circuit voltage value corresponding to the single battery and the time length between the first moment and the second moment corresponding to the single battery.
The calculation method of the self-discharge rate eta comprises the following steps:
(1) finding out corresponding SOC1 and SOC2 according to the detected V1 and V2 based on the OCV-SOC curve of the battery;
(2) calculating the SOC change value delta SOC of the battery according to the SOC1 and the SOC 2;
(3) calculating the battery capacity discharged by the battery from the discharge according to the delta SOC and the full-capacity C of the battery, wherein the delta Q is delta SOC C;
(4) calculating the value of the self-discharge rate eta of the battery: η ═ Δ Q/(t1-t 2). The larger the self-discharge rate, the more the battery loses capacity by self-discharge during standing, and the less its remaining capacity.
In step S52, a reference self-discharge rate is determined.
In one embodiment, the self-discharge rate of any single cell in the battery pack may be used as the reference self-discharge rate, for example, the self-discharge rate of the 2 nd single cell in the battery pack is used as the reference self-discharge rate, or the self-discharge rate of the single cell with the largest self-discharge rate in the battery pack, or the self-discharge rate of the single cell with the smallest self-discharge rate in the battery pack, or the self-discharge rate of the single cell with the self-discharge rate arranged in the middle of the battery pack (for the case that the battery pack includes an odd number of single cells).
In another embodiment, the reference self-discharge rate may also be calculated from the self-discharge rates of the individual cells in the battery pack, for example: the average value of the self-discharge rates of the individual unit cells in the battery pack, or the average value of the self-discharge rates of the two unit cells in the battery pack that have self-discharge rates that are arranged at the middle (for the case where the battery pack includes an even number of unit cells).
Optionally, the target equalization duration of the single battery to be equalized is determined according to the self-discharge rate and the reference self-discharge rate of the single battery to be equalized, and there are, but not limited to, the following determination manners:
according to Δ Q ═ Δ η × t0Determining the electric quantity difference, wherein delta Q is the electric quantity difference, delta eta is the self-discharge rate difference value between the self-discharge rate of the single battery to be equalized and the reference self-discharge rate, and t0The time length from the last time of equalization ending to the current time is obtained;
and determining a target equalization time length according to the t ═ delta Q/I, wherein t is the target equalization time length, and I is the equalization current of the single battery to be equalized.
And the balancing process of the single batteries needing balancing is different according to different reference self-discharge rates. Hereinafter, the self-discharge rates will be described with reference to the case where the self-discharge rates are the minimum value, the maximum value, and the average value among the self-discharge rates of the individual unit cells in the battery pack.
1) In the case that the reference self-discharge rate is the minimum value among the self-discharge rates of the individual single batteries in the battery pack, the determining the self-discharge rate difference between the self-discharge rate of the at least one single battery and the reference self-discharge rate required for the equalization judgment includes: determining the self-discharge rate difference between the self-discharge rates of the following single batteries and a reference self-discharge rate required by the equalization judgment:
the single battery with the maximum self-discharge rate in the battery pack; or
And the other single batteries except the single battery with the self-discharge rate of the minimum value in the battery pack.
Correspondingly, after determining that the single battery needing equalization is the single battery with the self-discharge rate difference value larger than or equal to the equalization starting threshold value in the at least one single battery, the method further comprises the following steps: and controlling the charging of the single battery with the self-discharge rate difference value larger than or equal to the equalizing starting threshold value in the at least one single battery.
Specifically, when the reference self-discharge rate is the minimum value among the self-discharge rates of the individual cells in the battery pack, only the self-discharge rate of the individual cell with the largest self-discharge rate in the battery pack may be subtracted from the reference self-discharge rate, so as to determine whether the individual cell with the largest self-discharge rate in the battery pack is the individual cell requiring equalization. This embodiment can only determine if one cell needs to be balanced.
When the reference self-discharge rate is the minimum value of the self-discharge rates of the single batteries in the battery pack, the self-discharge rates of the single batteries except the single battery with the minimum self-discharge rate in the battery pack can be differentiated from the reference self-discharge rate, so that whether the single batteries except the single battery with the minimum self-discharge rate in the battery pack are the single batteries needing to be balanced or not can be judged. This embodiment is a batch determination method, and can determine whether or not the other cells in the battery pack, except the cell with the smallest self-discharge rate, are the cells that need to be balanced at one time.
In the case that the reference self-discharge rate is the minimum value of the self-discharge rates of the single batteries in the battery pack, the process of balancing the single batteries needing balancing is as follows: no matter the battery pack is in a charging state or a discharging state, active equalization is adopted to charge the single batteries needing equalization.
2) In the case that the reference self-discharge rate is the maximum value of the self-discharge rates of the single batteries in the battery pack, determining the self-discharge rate difference between the self-discharge rate of the at least one single battery and the reference self-discharge rate required by the equalization judgment comprises: determining the self-discharge rate difference between the self-discharge rates of the following single batteries and a reference self-discharge rate required by the equalization judgment:
the single battery with the minimum self-discharge rate in the battery pack; or
And the other single batteries except the single battery with the self-discharge rate of the maximum value in the battery pack.
Correspondingly, after determining that the single battery needing equalization is the single battery with the self-discharge rate difference value larger than or equal to the equalization starting threshold value in the at least one single battery, the method further comprises the following steps: and controlling the discharge of the single battery with the self-discharge rate difference value larger than or equal to the balance starting threshold value in the at least one single battery.
Specifically, when the reference self-discharge rate is the maximum value among the self-discharge rates of the individual cells in the battery pack, only the self-discharge rate of the cell with the minimum self-discharge rate in the battery pack may be subtracted from the reference self-discharge rate, so as to determine whether the cell with the minimum self-discharge rate in the battery pack is the cell requiring equalization. This embodiment can only determine if one cell needs to be balanced.
When the reference self-discharge rate is the maximum value of the self-discharge rates of the single batteries in the battery pack, the self-discharge rates of the other single batteries except the single battery with the maximum self-discharge rate in the battery pack can be differentiated from the reference self-discharge rate, so as to judge whether the other single batteries except the single battery with the maximum self-discharge rate in the battery pack are the single batteries needing to be balanced. This embodiment is a batch determination method, and can determine whether or not the other cells in the battery pack, except the cell with the highest self-discharge rate, are the cells that need to be balanced at one time.
In the case that the reference self-discharge rate is the maximum value of the self-discharge rates of the single batteries in the battery pack, the process of balancing the single batteries needing balancing is as follows: no matter the battery pack is in a charging state or a discharging state, passive equalization is adopted, and the single batteries needing equalization are discharged.
3) In the case that the reference self-discharge rate is an average value of self-discharge rates of the single batteries in the battery pack, determining a self-discharge rate difference between the self-discharge rate of the at least one single battery and a reference self-discharge rate required for equalization judgment includes: and determining the self-discharge rate difference between the self-discharge rate of each single battery in the battery pack and the reference self-discharge rate.
Correspondingly, after determining that the single battery needing equalization is the single battery with the self-discharge rate difference value larger than or equal to the equalization starting threshold value in the at least one single battery, the method further comprises the following steps:
and controlling the single batteries with the self-discharge rates smaller than the average value to discharge, and controlling the single batteries with the self-discharge rates larger than the average value to charge.
Specifically, when the reference self-discharge rate is an average value of the self-discharge rates of the individual batteries in the battery pack, the self-discharge rate of each individual battery in the battery pack may be different from the reference self-discharge rate, so as to determine whether each individual battery in the battery pack is an individual battery that needs to be balanced. The embodiment is a batch judgment mode, and can judge whether each single battery in the battery pack is a single battery needing to be balanced at one time.
In the case that the reference self-discharge rate is an average value of self-discharge rates of the individual cells in the battery pack, the process of equalizing the individual cells requiring equalization is as follows: whether the battery pack is in a charging state or a discharging state, the active equalization is adopted for the single batteries with the self-discharge rate larger than the average value in the single batteries needing equalization, and the single batteries with the self-discharge rate larger than the average value in the single batteries needing equalization are charged; and (4) adopting passive equalization for the single batteries with the self-discharge rate smaller than the average value in the single batteries needing equalization, and discharging the single batteries with the self-discharge rate smaller than the average value in the single batteries needing equalization.
It should be understood that if it is determined that there is no single battery needing to be balanced, whether there is a single battery needing to be balanced is continuously judged according to the self-discharge rate of at least one single battery in the battery pack. When it is determined that no single battery needs to be balanced, the control module does not act, so that the balancing module corresponding to any battery is not started.
Fig. 6 is a schematic diagram of an equalizing module according to an embodiment of the disclosure. And controlling the single batteries to be balanced, wherein the balancing judgment needs to be combined. According to the step of equalization judgment, whether the equalization mode of the single battery to be equalized is passive equalization (namely, the single battery to be equalized is discharged) or active equalization (namely, the single battery to be equalized is charged) is determined, and the corresponding equalization module is conducted.
Referring to fig. 6, for passive equalization, the equalization module includes: and each single battery corresponds to one equalizing module, namely two ends of each single battery are connected with one resistor in parallel.
For the single battery to be balanced which needs to be passively balanced, the control module controls the conduction of a parallel loop between the single battery to be balanced and the corresponding resistor of the single battery to be balanced so as to execute the passive balancing of the single battery. Referring to fig. 6, the control module controls the switch module 812 to be turned on, so as to achieve the conduction of the parallel loop between the single battery to be balanced and the corresponding resistor.
The resistor 811 may be a fixed resistor or a variable resistor. In one embodiment, the resistor 811 may be a positive temperature coefficient thermistor, which may change with the temperature change, so as to adjust the balancing current generated during balancing, thereby automatically adjusting the heat generation amount of the battery balancing system, and finally effectively controlling the temperature of the battery balancing system.
Referring to fig. 6, for active equalization, the equalization module includes a charging branch 94 connected in parallel with each battery cell 95 in the battery pack, the charging branches 94 correspond to the battery cells 95 one by one, and each charging branch 94 is connected to the generator 92, and the generator 92 is mechanically connected to the engine 91 through a gear.
For the single battery to be equalized which needs to be actively equalized, the control module controls the charging branch 94 corresponding to the single battery to be equalized to be conducted. When the engine 91 rotates, the generator 92 is driven to generate electricity, so that the electricity generated by the generator 92 is transmitted to the single battery to be balanced, and the electricity of the single battery to be balanced is increased.
Referring to fig. 6, when the generator 92 is an alternator, the equalizing module further comprises a rectifier 93 connected in series with the generator 92, each charging branch 130 being connected in series with the rectifier 132. After the alternating current generated by the generator 92 is converted into direct current by the rectifier 93, the generator 92 can be used for charging the single battery to be equalized.
Referring to fig. 6, the control module may control the switch 96 corresponding to the single battery to be equalized to be turned on, so that the charging branch corresponding to the single battery to be equalized is turned on, and active equalization of the single battery to be equalized is performed.
In other embodiments, in addition to the charging of the single batteries by the generator shown in fig. 6, the single batteries to be equalized may also be charged by the starting battery in the entire vehicle.
In another embodiment, in addition to the parallel resistor and the single battery to be balanced shown in fig. 6, the single battery to be balanced may be connected in parallel with a starting battery of the whole vehicle, and the electric quantity discharged by the single battery to be balanced is charged into the starting battery, so that the balancing of the single battery to be balanced is realized while energy waste is effectively avoided.
As described above, in the embodiment of the present disclosure, a plurality of single batteries may share one balancing module, and when at least two single batteries among a plurality of single batteries sharing one balancing module need to be balanced, the balancing module is alternately connected to each single battery among the at least two single batteries needing to be balanced, and the balancing module performs balancing respectively.
Correspondingly, the embodiment of the disclosure also provides a vehicle, which comprises the battery equalization system.
Accordingly, the disclosed embodiments also provide a computer readable storage medium, on which computer program instructions are stored, and the program instructions, when executed by a processor, implement the above battery equalization method.
Correspondingly, the embodiment of the present disclosure further provides an electronic device, including: the aforementioned computer-readable storage medium; and one or more processors for executing the program in the computer-readable storage medium.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.

Claims (19)

1. A method of balancing a battery, comprising:
acquiring the self-discharge rate of a single battery to be balanced in a battery pack;
acquiring a reference self-discharge rate required by equalization;
determining the target equalization duration of the single battery to be equalized according to the self-discharge rate of the single battery to be equalized and the reference self-discharge rate;
controlling the balance of the single batteries to be balanced according to the target balancing duration;
the determining the target equalization duration of the single battery to be equalized according to the self-discharge rate of the single battery to be equalized and the reference self-discharge rate comprises the following steps:
according to Δ Q ═ Δ η × t0Determining an electric quantity difference, wherein delta Q is the electric quantity difference, delta eta is a self-discharge rate difference value between the self-discharge rate of the single battery to be equalized and the reference self-discharge rate, and t0The time length from the last time of equalization ending to the current time is obtained;
and determining the target balancing time length according to the t ═ delta Q/I, wherein t is the target balancing time length, and I is the balancing current of the single battery to be balanced.
2. The method according to claim 1, wherein the obtaining of the self-discharge rate of the single battery to be equalized in the battery pack comprises:
after the battery pack is powered off, determining a first time when each single battery in the battery pack reaches a stable state and a first open-circuit voltage value corresponding to the single battery at the first time;
when the battery pack is electrified again, determining a second time when the single battery is electrified and a second open-circuit voltage value of the single battery at the second time for each single battery in the battery pack;
and determining the self-discharge rate of the single battery according to the first open-circuit voltage value and the second open-circuit voltage value corresponding to the single battery and the duration between the first moment and the second moment corresponding to the single battery.
3. The method of claim 1, wherein the obtaining of the reference self-discharge rate required for equalization comprises:
determining the minimum value of the self-discharge rates of the single batteries in the battery pack as the reference self-discharge rate;
the controlling the balancing of the single battery to be balanced according to the target balancing duration comprises the following steps:
and controlling the charging of the single battery to be equalized according to the target equalization duration.
4. The method of claim 1, wherein the obtaining of the reference self-discharge rate required for equalization comprises:
determining the maximum value of the self-discharge rates of the single batteries in the battery pack as the reference self-discharge rate;
the controlling the balancing of the single battery to be balanced according to the target balancing duration comprises the following steps:
and controlling the discharge of the single battery to be balanced according to the target balancing duration.
5. The method of claim 1, wherein the obtaining of the reference self-discharge rate required for equalization comprises:
determining the average value of the self-discharge rates of the single batteries in the battery pack as the reference self-discharge rate;
the controlling the balancing of the single battery to be balanced according to the target balancing duration comprises the following steps:
and controlling the single batteries with the self-discharge rates smaller than the average value to discharge, and controlling the single batteries with the self-discharge rates larger than the average value to charge.
6. The method according to any one of claims 1-5, further comprising:
determining the single batteries to be balanced from the battery pack according to battery parameter information of each single battery in the battery pack, wherein the battery parameter information comprises at least one of a load voltage value, an SOC value, an internal resistance value, a voltage change rate, an electric quantity change rate and a time change rate, the voltage change rate is used for representing the change of the load voltage value of the single battery along with the change unit value of the physical quantity, the electric quantity change rate is the electric quantity required to be charged or discharged for enabling the load voltage value of the single battery to change by the unit value, and the time change rate is the charging duration or the discharging duration required for enabling the load voltage value of the single battery to change by the unit value.
7. A battery equalization system, comprising:
a balancing module, an acquisition module and a control module,
the acquisition module is used for: acquiring the self-discharge rate of a single battery to be balanced in a battery pack;
the control module is used for: acquiring a reference self-discharge rate required by balancing, and determining a target balancing time length of the single battery to be balanced according to the self-discharge rate of the single battery to be balanced and the reference self-discharge rate;
the equalization module is configured to: balancing the single batteries to be balanced according to the target balancing duration;
the control module is used for:
according to Δ Q ═ Δ η × t0Determining an electric quantity difference, wherein delta Q is the electric quantity difference, delta eta is a self-discharge rate difference value between the self-discharge rate of the single battery to be equalized and the reference self-discharge rate, and t0The time length from the last time of equalization ending to the current time is obtained;
and determining the target balancing time length according to the t ═ delta Q/I, wherein t is the target balancing time length, and I is the balancing current of the single battery to be balanced.
8. The battery equalization system of claim 7, wherein the acquisition module is configured to:
after the battery pack is powered off, determining a first time when each single battery in the battery pack reaches a stable state and a first open-circuit voltage value corresponding to the single battery at the first time;
when the battery pack is electrified again, determining a second time when the single battery is electrified and a second open-circuit voltage value of the single battery at the second time for each single battery in the battery pack;
and determining the self-discharge rate of the single battery according to the first open-circuit voltage value and the second open-circuit voltage value corresponding to the single battery and the duration between the first moment and the second moment corresponding to the single battery.
9. The battery equalization system of claim 7, wherein the control module is configured to:
determining the minimum value of the self-discharge rates of the single batteries in the battery pack as the reference self-discharge rate;
the equalization module is configured to:
and charging the single battery to be equalized according to the target equalization duration.
10. The battery equalization system of claim 7, wherein the control module is configured to:
determining the maximum value of the self-discharge rates of the single batteries in the battery pack as the reference self-discharge rate;
the equalization module is configured to:
and discharging the single battery to be balanced according to the target balancing duration.
11. The battery equalization system of claim 7, wherein the control module is configured to:
determining the average value of the self-discharge rates of the single batteries in the battery pack as the reference self-discharge rate;
the equalization module is configured to:
discharging the single batteries with the self-discharge rates smaller than the average value in the single batteries to be equalized, and charging the single batteries with the self-discharge rates larger than the average value in the single batteries to be equalized.
12. The battery equalization system of any of claims 7-11, wherein the control module is configured to:
determining the single batteries to be balanced from the battery pack according to battery parameter information of each single battery in the battery pack, wherein the battery parameter information comprises at least one of a load voltage value, an SOC value, an internal resistance value, a voltage change rate, an electric quantity change rate and a time change rate, the voltage change rate is used for representing the change of the load voltage value of the single battery along with the change unit value of the physical quantity, the electric quantity change rate is the electric quantity required to be charged or discharged for enabling the load voltage value of the single battery to change by the unit value, and the time change rate is the charging duration or the discharging duration required for enabling the load voltage value of the single battery to change by the unit value.
13. The battery equalization system of claim 7, wherein the control module is connected to the acquisition module and the equalization module corresponding to the same cell through a channel,
the control module is used for controlling the control module to be connected with the corresponding sampling module when the single battery connected with the control module is determined not to need balancing; alternatively, the first and second electrodes may be,
the control module is further used for multiplexing the channels in a time-sharing manner by the acquisition module and the balancing module when the single battery connected with the control module needs to be balanced.
14. The battery equalization system of claim 13, wherein the control module comprises a control chip, and the control chip is connected to the acquisition module and the equalization module corresponding to the same cell through one pin and the one channel.
15. The battery equalization system of claim 7, wherein the control module is connected to the acquisition module and the equalization module corresponding to the same cell through two channels.
16. The battery equalization system of claim 15, wherein the control module comprises a control chip, the control chip is connected to the acquisition module and the equalization module corresponding to the same cell through two pins, and the two pins are in one-to-one correspondence with the two channels.
17. A computer-readable storage medium, on which computer program instructions are stored, which program instructions, when executed by a processor, implement the method of any one of claims 1-6.
18. An electronic device, comprising:
the computer-readable storage medium recited in claim 17; and
one or more processors to execute the program in the computer-readable storage medium.
19. A vehicle, characterized in that the vehicle comprises: a battery pack and a battery equalization system as claimed in any of claims 7-16.
CN201710776101.1A 2017-08-31 2017-08-31 Battery equalization method, system, vehicle, storage medium and electronic device Active CN110015129B (en)

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