CN110015186B - 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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CN110015186B
CN110015186B CN201710775043.0A CN201710775043A CN110015186B CN 110015186 B CN110015186 B CN 110015186B CN 201710775043 A CN201710775043 A CN 201710775043A CN 110015186 B CN110015186 B CN 110015186B
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equalization
battery
self
single battery
discharge rate
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CN110015186A (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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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION 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
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION 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
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION 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
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18—Methods 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
    • B60L58/22—Balancing the charge of battery modules
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/54—Drive Train control parameters related to batteries
    • B60L2240/547—Voltage
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy 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 each single battery in the battery pack; acquiring a reference self-discharge rate required by equalization; determining a target equalization duration of a single battery to be equalized according to a self-discharge rate of the single battery to be equalized in the battery pack, the reference self-discharge rate and a preset equalization duty ratio, wherein the equalization duty ratio is a ratio of an equalization time period in a unit cycle to the unit cycle, and the unit cycle comprises the equalization time period and a sampling time period; and controlling the balance of the single battery to be balanced in the balancing time period of the unit cycle according to the target balancing duration.

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 differences between the single batteries may result in some single batteries being overcharged, some single batteries being overdischarged, which may affect the battery life and damage the batteries, and may also generate a large amount of heat to cause the batteries to burn or explode.
Therefore, the method has the advantages of effectively and uniformly managing the power batteries of the electric automobile, being beneficial to improving the consistency of the batteries in the power battery pack, reducing the capacity loss of the batteries, prolonging the service life of the batteries and the driving range of the electric automobile, and having very important significance.
At present, when a battery pack is subjected to equalization management, battery information of each single battery in the battery pack is usually acquired in real time, whether the single battery needs to be equalized or not is determined according to the acquired battery information, and when the single battery needs to be equalized, the equalization duration of the single battery is further determined according to the battery information. However, in such a manner, equalization may be performed while acquiring battery information, and fluctuation of the battery information may be caused in the equalization process, which may cause inaccuracy of the acquired battery information, and further cause inaccuracy of the calculated equalization duration and poor equalization effect when a single battery needs equalization.
Disclosure of Invention
The method can separately perform sampling and equalization in a unit period, ensures the accuracy of acquired battery information, calculates the equalization duration accurately, and improves the equalization effect of a battery pack.
In order to achieve the above object, in a first aspect, the present disclosure provides a battery equalization method, including:
acquiring the self-discharge rate of each single battery in the battery pack;
acquiring a reference self-discharge rate required by equalization;
determining a target equalization duration of a single battery to be equalized according to a self-discharge rate of the single battery to be equalized in the battery pack, the reference self-discharge rate and a preset equalization duty ratio, wherein the equalization duty ratio is a ratio of an equalization time period to a unit cycle in the unit cycle, and the unit cycle comprises the equalization time period and a sampling time period;
and controlling the balance of the single battery to be balanced in the balancing time period of the unit cycle according to the target balancing duration.
In a second aspect, the present disclosure provides a battery equalization system, the system comprising: the device comprises a balancing module, an acquisition module and a control module;
the acquisition module is used for acquiring battery information of a battery pack, and the battery information is used for determining the self-discharge rate of each single battery in the battery pack;
the control module is used for acquiring the self-discharge rate of each single battery in the battery pack; acquiring a reference self-discharge rate required by equalization; determining a target equalization duration of a single battery to be equalized according to a self-discharge rate of the single battery to be equalized in the battery pack, the reference self-discharge rate and a preset equalization duty ratio, wherein the equalization duty ratio is a ratio of an equalization time period in a unit cycle to the unit cycle, and the unit cycle comprises the equalization time period and a sampling time period; controlling the balance of the single battery to be balanced in the balancing time period of the unit cycle according to the target balancing duration;
the balancing module is used for balancing the single batteries to be balanced.
In a third aspect, the present disclosure provides a vehicle comprising the battery equalization system of the second aspect.
In a fourth aspect, 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 described above.
In a fifth aspect, the present disclosure provides an electronic device comprising:
the computer-readable storage medium of the fourth aspect; and one or more processors to execute the program in the computer-readable storage medium.
Through the technical scheme, the acquisition and the balance of the battery information are carried out in time in a unit period, so that the influence of the balance current on the accuracy of the battery information acquisition is avoided when the acquisition and the balance of the battery information are carried out simultaneously; on the other hand, the proportion of the equalization time period to the adopted time period in the unit time length can be reflected through the equalization duty ratio, so that the target equalization time length calculated under the condition of considering the equalization duty ratio can better equalize the single batteries needing equalization, and meanwhile, a novel method for determining the target equalization time length is provided.
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: a control module 101, an acquisition module 102 and a balancing module 103. The battery equalization system can be used to equalize the battery pack 104.
In one embodiment, each single battery 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 carried out simultaneously.
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 single battery 111 of the two single batteries is switched from the closed state to the open state or from the open state to the closed state every two seconds within 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, and an equalization module 303, which can be used to equalize a battery pack 304. The battery pack 304 includes a plurality of unit cells connected in series. The control module 301 is connected with the acquisition module 302 and the equalization module 303 corresponding to the same single battery through a control channel 305, and the control module 301 is used for controlling the control module 301 to be connected with the corresponding sampling module 302 when determining that the single battery connected with the control module 301 does not need to be equalized; or, the control module 301 is further configured to multiplex the channels 305 in a time-sharing manner according to a unit period by the acquisition module 302 and the equalization module 303 when it is determined that the single battery connected to the control module 301 needs to be equalized.
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 (State of Charge), 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 same control channel is shared between the acquisition module and the balancing module, the control module controls the acquisition module and the balancing module, and the control channel is multiplexed in a time-sharing manner 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. 3, 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 single cells may share an equalization module, for example, N single cells in a battery pack, the same equalization module may be shared, or one equalization module may be shared for each predetermined number (for example, 2, 3, or 5, etc.) of single cells, and the like. 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 connections may be connections that alternate according to a certain periodicity. 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, the self-discharge rate of each unit cell in the battery pack is acquired.
In step S52, a reference self-discharge rate required for equalization is acquired.
In step S53, a target equalization duration of the single battery to be equalized is determined according to a self-discharge rate of the single battery to be equalized in the battery pack, a reference self-discharge rate, and a preset equalization duty ratio, where the equalization duty ratio is a ratio of an equalization period to a unit cycle in a unit cycle, and the unit cycle includes the equalization period and a sampling period.
In step S54, the balancing of the unit cells to be balanced is controlled in the balancing period of the unit cycle in accordance with the target balancing duration.
In the sampling period of the unit cycle, the control module controls the acquisition module to acquire the battery information of each single battery in the battery pack respectively, and the self-discharge rate of each single battery can be obtained through the battery information. Wherein, the battery information may for example comprise at least one of the following information: voltage, current, and temperature. At this point, the equalization module stops operating.
And in the balancing time period of the unit cycle, the control module controls the balancing module to balance the module to be balanced in the battery pack. At this point, the sampling module stops operating.
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 (at the time t 1), detecting and recording an open-circuit voltage value V1 of each single battery of the power battery pack; when the battery pack starts to work again (at the moment of t 2), 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 each single battery in the battery pack is electrified and a second open-circuit voltage value of each single battery at the second time;
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 aiming at each monomer in the battery pack when the battery pack reaches a stable stateA battery for detecting and recording a first time t when the single battery reaches a stable state 1 And the open circuit voltage value V of the single battery 1 。
When the battery pack is electrified again, determining a second time when each single battery in the battery pack is electrified and a second open-circuit voltage value of each single battery at the second time.
And restarting the battery pack to start working when the battery pack is electrified again, and detecting and recording a second moment t when each single battery in the battery pack is electrified 2 And a second open circuit voltage value V at that time 2 。
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.
In one embodiment, the self-discharge rate value η of the unit cell may be determined according to the following method:
(1) Based on an Open Circuit Voltage (OCV) curve of the battery, finding out corresponding SOC1 and SOC2 according to the detected V1 and V2;
(2) Calculating the SOC change value delta SOC of the battery according to the SOC1 and the SOC2;
(3) Calculating the battery capacity discharged by the battery from discharging according to the delta SOC and the full-capacity C of the battery, wherein delta Q = delta SOC C;
(4) Calculating the value of the self-discharge rate eta of the battery: η = Δ Q/(t 1-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.
The reference self-discharge rate may be obtained according to the self-discharge rate of each unit cell, and in one embodiment, the self-discharge rate of any unit cell in the battery pack may be used as the reference self-discharge rate, for example, the self-discharge rate of the 2 nd unit cell in the battery pack is used as the reference self-discharge rate, or the self-discharge rate of the unit cell with the largest self-discharge rate in the battery pack, or the self-discharge rate of the unit cell with the smallest self-discharge rate in the battery pack, or the self-discharge rate of the unit 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 unit 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 single battery to be equalized may be a single battery to be equalized, which is determined by some performance parameters of the battery in the battery pack, and the performance parameters used for determining the single battery to be equalized may include, for example, a voltage value, an SOC, an internal resistance, a self-discharge rate, a voltage change rate, an electric quantity change rate, a time change rate, and the like.
Referring to table 1 below, table 1 exemplifies a manner for determining a single battery to be equalized from a battery pack when parameters of the single battery to be equalized are respectively a voltage value, an SOC, an internal resistance, a self-discharge rate, a voltage change rate, an electric quantity change rate, or a time change rate, and a manner for subsequently equalizing the corresponding single battery to be equalized after determining the single battery to be equalized.
The voltage change rate of the unit cells may be a voltage change amount at which a unit change of a specified physical quantity of the unit cells occurs. For example, in the present disclosure, to charge or discharge a preset amount of electricity to or from a unit cell, a voltage variation amount (dv/dq) of the unit cell; or, a preset time period for charging or discharging the single battery, and a voltage variation (dv/dt) of the single battery will be described as an example.
The rate of change in the amount of charge of the unit cells may be an amount of change in the amount of charge when a unit of a specified physical quantity of the unit cells is changed. For example, the present disclosure will be described by taking as an example the amount of electricity (dq/dv) charged to increase the voltage of the cell by one unit voltage from the initial voltage, or the amount of electricity (dq/dv) decreased by decreasing the voltage of the cell by one unit voltage from the initial voltage.
The time change rate of the unit cells may be a time change amount at which a unit change of a specified physical quantity of the unit cells occurs. For example, the present disclosure will be described taking as an example a charging time (dt/dv) required for the voltage of the unit cell to rise by one unit voltage from the initial voltage, or a discharging time (dt/dv) required for the voltage of the unit cell to fall by one unit voltage from the initial voltage.
TABLE 1
Figure BDA0001395750530000101
Figure BDA0001395750530000111
Figure BDA0001395750530000121
Figure BDA0001395750530000131
In the embodiment of the present disclosure, the equalization duty ratio is a ratio of an equalization period to the unit period in the unit period, and may be used to represent a ratio of the equalization period to the sampling period in the unit period. The preset equalization duty cycle may be a preset equalization duty cycle, an equalization duty cycle that is not changed during equalization, such as a setting of 50%, and so on.
Optionally, after determining the single battery needing to be balanced, the target balancing time length of the single battery needing to be balanced may be determined, and then the single battery needing to be balanced is balanced according to the determined target balancing time length. The target equalization duration is determined according to the self-discharge rate of the single batteries needing equalization, the reference self-discharge rate and the preset equalization duty ratio.
Optionally, the target equalization duration of the single battery to be equalized is determined according to the self-discharge rate of the single battery to be equalized, a reference self-discharge rate and a preset equalization duty ratio, and there are two determination methods without limitation:
the first determination method:
first, Δ Q = Δ η × t 0 Determining the electric quantity difference, wherein delta Q is the electric quantity difference, delta eta is the difference value between the self-discharge rate of the single battery to be equalized and the reference self-discharge rate, and t 0 The time length from the last time of equalization ending to the current time is obtained;
next, a target equalization duration is determined according to t = Δ Q/(I × τ), where t is the target equalization duration, I is the set equalization current, and τ is the equalization duty cycle.
The second mode is as follows:
and determining the target equalization time length of the single battery to be equalized according to the self-discharge rate difference value and the equalization duty ratio between the self-discharge rate and the reference self-discharge rate of the single battery to be equalized and the corresponding relation among the preset self-discharge rate difference value, the equalization duty ratio and the target equalization time length.
The preset self-discharge rate difference, the equalization duty cycle and the equalization duration may be obtained through multiple equalization tests or experiences, for example, recorded in a table, and then the measured self-discharge rate difference and the corresponding target equalization duration value under the preset equalization duty cycle may be searched in the table.
After the target equalization duration is obtained, the equalization single batteries can be equalized according to the target equalization duration in the equalization time period of the unit cycle.
Equalization process
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 in the balancing time period of the unit cycle, wherein the balancing needs to be carried out in combination with the balancing judgment. And in the step of judging the equalization, determining whether the equalization mode of the single battery to be equalized is passive equalization (namely, discharging the single battery to be equalized) or active equalization (namely, charging the single battery to be equalized), and conducting the corresponding equalization module.
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, in the balancing time period of the unit cycle, 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 thermistor with a positive temperature coefficient, which may change with the temperature, 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 in a balancing period of a unit cycle, and balancing is performed separately.
Correspondingly, the embodiment of the disclosure also provides a vehicle, which comprises the battery equalization system.
Accordingly, embodiments of the present disclosure further provide a computer-readable storage medium, on which computer program instructions are stored, and when the computer program instructions are executed by a processor, the computer program instructions implement the above battery balancing 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.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims (15)

1. A method of cell balancing, the method comprising:
acquiring the self-discharge rate of each single battery in the battery pack;
acquiring a reference self-discharge rate required by equalization;
determining a target equalization duration of a single battery to be equalized according to a self-discharge rate of the single battery to be equalized in the battery pack, the reference self-discharge rate and a preset equalization duty ratio, wherein the equalization duty ratio is a ratio of an equalization time period to a unit cycle in the unit cycle, and the unit cycle comprises the equalization time period and a sampling time period;
controlling the balance of the single battery to be balanced in the balancing time period of the unit cycle 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 in the battery pack, the reference self-discharge rate and the preset equalization duty ratio comprises the following steps:
as Δ Q = Δ η × t 0 Determining an electric quantity difference, wherein delta Q is the electric quantity difference, delta eta is the difference value between the self-discharge rate of the single battery to be equalized and the reference self-discharge rate, t 0 The time length from the last time of equalization ending to the current time is obtained;
and determining the target equalization time length according to t = delta Q/(I multiplied by tau), wherein t is the target equalization time length, I is the set equalization current, and tau is the equalization duty ratio.
2. The method of claim 1, wherein the reference self-discharge rate is a minimum value among self-discharge rates of the respective unit cells, a maximum value among self-discharge rates of the respective unit cells, or an average value among self-discharge rates of the respective unit cells.
3. The method according to claim 2, wherein the controlling the balancing of the unit cells to be balanced in the balancing period of the unit cycle comprises:
if the reference self-discharge rate is the minimum value of the self-discharge rates of the single batteries, controlling the single batteries to be equalized to be charged in the equalization time period of the unit cycle; or the like, or, alternatively,
if the reference self-discharge rate is the maximum value of the self-discharge rates of the single batteries, controlling the single batteries to be balanced to discharge in the balancing time period of the unit period; or the like, or, alternatively,
if the reference self-discharge rate is the average value of the self-discharge rates of the single batteries: when the self-discharge rate of the single battery to be equalized is greater than the reference self-discharge rate, controlling the single battery to be equalized to be charged in the equalization time period of the unit cycle; and when the self-discharge rate of the single battery to be balanced is smaller than the reference self-discharge rate, controlling the single battery to be balanced to discharge in the balancing time period of the unit period.
4. The method of claim 1, wherein obtaining the self-discharge rate of each cell 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 each single battery in the battery pack is electrified and a second open-circuit voltage value of each single battery at the second time;
and determining the self-discharge rate value 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.
5. The method according to any one of claims 1-4, further comprising:
and 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 voltage value, an internal resistance value, an SOC value, a voltage change rate, an electric quantity change rate and a time change rate.
6. A battery equalization system, comprising: a balancing module, an acquisition module and a control module,
the acquisition module is used for acquiring battery information of a battery pack, and the battery information is used for determining the self-discharge rate of each single battery in the battery pack;
the control module is used for acquiring the self-discharge rate of each single battery in the battery pack; acquiring a reference self-discharge rate required by equalization; determining a target equalization duration of a single battery to be equalized according to a self-discharge rate of the single battery to be equalized in the battery pack, the reference self-discharge rate and a preset equalization duty ratio, wherein the equalization duty ratio is a ratio of an equalization time period to a unit cycle in the unit cycle, and the unit cycle comprises the equalization time period and a sampling time period; controlling the balance of the single battery to be balanced in the balancing time period of the unit cycle according to the target balancing duration;
the balancing module is used for balancing the single batteries to be balanced;
the control module is used for:
at Δ Q = Δ η × t 0 Determining an electric quantity difference, wherein delta Q is the electric quantity difference, delta eta is the difference value between the self-discharge rate of the single battery to be equalized and the reference self-discharge rate, t 0 The time length from the last time of equalization ending to the current time is obtained;
and determining the target equalization time length according to t = delta Q/(I multiplied by tau), wherein t is the target equalization time length, I is the set equalization current, and tau is the equalization duty ratio.
7. The battery equalization system of claim 6, wherein the control module is configured to:
after the battery pack is powered off, determining a first time when the single battery to be balanced 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 moment when the single battery to be balanced is electrified and a second open-circuit voltage value of the single battery at the second moment;
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 to be balanced and the duration between the first moment and the second moment corresponding to the single battery to be balanced.
8. The battery equalization system of any of claims 6-7, wherein the control module is configured to:
and determining the single batteries to be balanced from the battery pack according to the battery parameter information of each single battery in the battery pack, wherein the battery parameter information comprises at least one of a voltage value, an internal resistance value, an SOC value, a voltage change rate, an electric quantity change rate and a time change rate.
9. The battery equalization system of claim 6, wherein the control module is connected with the acquisition module and the equalization module corresponding to the same single battery through a channel, and the control module is configured to control the control module to be connected with the corresponding sampling module when it is determined that the single battery connected with the control module does not need equalization; 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.
10. The battery equalization system of claim 9, wherein the control module comprises a control chip, and the control chip is connected with the acquisition module and the equalization module corresponding to the same cell through one pin and the one channel.
11. The battery equalization system of claim 6, wherein the control module is connected to the acquisition module and the equalization module corresponding to the same cell through two channels.
12. The battery equalization system of claim 11, 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.
13. A vehicle, characterized in that the vehicle comprises: a battery pack and a battery equalization system as claimed in any of claims 6-12.
14. A computer-readable storage medium, on which computer program instructions are stored, characterized in that the program instructions, when executed by a processor, implement the method of any of claims 1-5.
15. An electronic device, comprising:
the computer-readable storage medium recited in claim 14; and
one or more processors to execute the program in the computer-readable storage medium.
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