CN107579552A - Battery pack balancing control method and device - Google Patents

Abstract

The present invention relates to battery pack balancing control technology field, and in particular to a kind of single battery group balance control method, a kind of energy-storage system battery pack balancing control method and a kind of energy-storage system cell balance control unit.The balance control method comprises the following steps：Obtain each SOC of the battery core and average SOC of the battery pack in N number of battery core；The battery core for the average SOC that control SOC is more than battery pack is discharged N number of battery core of battery pack.The self discharge inside single battery group of the battery pack balancing control method of the present invention is balanced, is not lost externally, while above-mentioned self discharge equilibrium has overvoltage and under-voltage protection function, and damage or the lost of life of battery will not be caused because of overcharge or overdischarge.

Description

Battery pack balancing control method and device

technical field

The invention relates to the technical field of battery group balance control, in particular to a single battery group balance control method, a battery group balance control method for an energy storage system, and a battery group balance control device for an energy storage system.

Background technique

In the prior art, there are many battery balancing control methods, such as passive balancing method (energy splitting method), active balancing method (dynamic balancing method), internal balancing method (natural balancing method), and the like.

Among them, the passive equalization method adopts the method of parallel connection of single batteries to shunt energy-consuming electrons, and through the method of discharge equalization, the voltage of all batteries in the PACK tends to be consistent during the charging process. The passive equalization method has the following disadvantages: the excess energy is consumed to the resistance to generate heat, the efficiency is 0, and the energy is wasted; the equalization current is very small, usually less than 100mA; since the discharge resistance cannot be selected too small, when the charging ends, according to the characteristics of the battery Usually, the voltage of the small-capacity battery is the highest. During static equalization, it is precisely the power of the small-capacity battery that is discharged, which increases the mutual difference between the batteries; the SOC estimation accuracy is also very low.

The active equalization method actively equalizes the individual capacity of the battery during use and the voltage difference generated by the self-discharge rate; during the charging, discharging or placement of the battery pack, the battery cells can be adjusted within the battery pack. The differences are actively balanced to eliminate various inconsistencies caused by the batteries themselves and during use. The active equalization method has the following disadvantages: complex technology, high cost, and difficult implementation; frequent switching of the equalization circuit will cause great damage to the battery and affect the life of the battery.

The internal balance method uses the BMS to adjust the charging current and control the topology algorithm of the charging voltage in the process of charging the series batteries, so that the charging capacity of each single battery in the battery pack is basically the same. The internal balance method has the following disadvantages: if the charge of the battery is very different, it will take a long time to balance.

At present, neither the passive equalization technology nor the active equalization technology can solve the problem well. The reason is that the current commonly used charge and discharge control process uses a fixed voltage as the termination condition for charge and discharge, while the effective voltage range of the battery is constantly changing with the conditions such as temperature, charge and discharge current, and cycle time during the working process. Therefore, using a fixed voltage to control charge and discharge can easily cause overcharge or overdischarge of the battery. The temperature change will cause the aging of the internal materials of the lithium battery, causing the battery to deteriorate prematurely.

In view of this, to overcome the above defects in the prior art and to provide a new battery pack balancing control method has become a technical problem to be solved urgently in this field.

Contents of the invention

The object of the present invention is to address the above-mentioned defects of the prior art, and provide a method for balancing control of a single battery group, a method for controlling balance of a battery group in an energy storage system, and a device for balancing control of a battery group in an energy storage system.

The purpose of the present invention can be achieved through the following technical measures:

In a first aspect, the present invention provides a method for balancing control of a battery pack, wherein the battery pack includes N cells, and the method for balancing control includes the following steps:

S11. Obtain the SOC of each of the N cells and the average SOC of the battery pack;

S12, controlling the cells whose SOC is greater than the average SOC of the battery pack to discharge the N cells of the battery pack.

Preferably, in step S12, the discharged power of the cells whose SOC is greater than the average SOC of the battery pack is collected, and then the collected discharged power is charged to the N cells of the battery pack.

In a second aspect, the present invention provides a battery pack balance control method for an energy storage system. The energy storage system includes a plurality of battery packs, and each battery pack includes N cells. The balance control method includes the following steps:

S1, performing balanced control on each battery group of the energy storage system according to the single battery group balancing control method described in claim 1 or 2;

S2. Obtain the SOC of each battery pack in the plurality of battery packs and the average SOC of the energy storage system;

S3, controlling the battery pack whose SOC is greater than the average SOC of the energy storage system to discharge the battery pack whose SOC is smaller than the average SOC of the energy storage system.

Preferably, in step S3, the battery packs whose SOC is greater than the average SOC of the energy storage system are discharged to the power supply circuit of the energy storage system, and the battery packs whose SOC is smaller than the average SOC of the energy storage system are charged from the power supply circuit of the energy storage system.

Preferably, in step S3, it is judged whether the current energy storage system is in a power supply interruption state; if yes, the battery pack whose SOC is greater than the average SOC of the energy storage system and the battery pack whose SOC is smaller than the average SOC of the energy storage system are respectively controlled with different duty ratios. The battery pack of the SOC discharges to the power supply circuit.

In a third aspect, the present invention provides a battery pack balancing control device for an energy storage system. The energy storage system includes a plurality of battery packs, and each battery pack includes N cells. The balancing control device includes:

The battery pack equalization control component corresponding to each of the plurality of battery packs includes: a detection module for obtaining the SOC of each of the N battery cells and the average SOC of the battery pack, and for A balance module that controls the cells whose SOC is greater than the average SOC of the battery pack to discharge the N cells of the battery pack;

A charging and discharging assembly connected to each of the plurality of battery packs is used to charge and discharge the connected battery packs, and the charging and discharging assembly includes a switch module for connecting or disconnecting the power supply circuit of the energy storage system;

a detection component for obtaining the SOC of each battery pack in the plurality of battery packs and the average SOC of the energy storage system; and

A control component connected to multiple charging and discharging components, used to control the battery pack whose SOC is greater than the average SOC of the energy storage system to discharge to the power supply circuit of the energy storage system, and the battery pack whose SOC is smaller than the average SOC of the energy storage system to discharge from the energy storage system The power supply circuit charging.

Preferably, the equalization module includes:

A charging and discharging unit connected to each of the N battery cells, used to charge and discharge the connected battery cells;

an electricity storage unit connected to a plurality of charging and discharging units for storing electricity; and

A control unit connected to all the N batteries, used to control the batteries whose SOC is greater than the average SOC of the battery pack to discharge the power storage unit, and the power storage unit to charge the N batteries of the battery pack Charge.

Preferably, the battery pack balancing control device further includes a voltage monitoring module connected to the power supply circuit, configured to detect the voltage of the power supply circuit and judge whether the current energy storage system is in a power supply interruption state according to the detected voltage.

Preferably, the control component includes a PWM control module, which is used to control the battery pack whose SOC is greater than the average SOC of the energy storage system and the battery pack whose SOC is smaller than the average The connection between the battery pack of the SOC and the power supply circuit is disconnected.

Preferably, the control component is a single-chip microcomputer.

The battery pack equalization control method of the present invention achieves self-discharge balance inside the single battery pack without external loss, and at the same time, the above-mentioned self-discharge balance has overvoltage and undervoltage protection functions, and will not cause damage to the battery or shorten the life of the battery due to overcharging or overdischarging . Furthermore, the method and device for balancing control of battery packs in the energy storage system of the present invention perform charging and discharging balancing through the power supply circuit of the system, and supply power while the system is balancing. Furthermore, the method and device for balancing control of battery packs in an energy storage system of the present invention assist in power supply when the system is in a power supply interruption state, so as to achieve uninterrupted power supply of the system and prolong the service life of the system.

Description of drawings

FIG. 1 is a flow chart of a method for balancing a battery pack in an embodiment of the present invention.

Fig. 2 is a flow chart of a method for balancing control of battery packs in an energy storage system according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a method for balancing control of battery packs in an energy storage system according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of the auxiliary power supply of the energy storage system battery group equalization control method according to the embodiment of the present invention.

Fig. 5 is a structural block diagram of an energy storage system battery pack balance control device according to an embodiment of the present invention.

Fig. 6 is a structural block diagram of a battery pack balancing control component in a battery pack balancing control device for an energy storage system according to an embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

In the following text, many aspects of the invention will be better understood with reference to the accompanying drawings. Components in the figures are not necessarily drawn to scale. Instead, emphasis is placed on clearly illustrating the components of the invention. Furthermore, like reference numerals indicate corresponding parts throughout the several views of the drawings.

As used herein, the word "exemplary" or "illustrative" means serving as an example, instance, or illustration. Any implementation described herein as "exemplary" or "illustrative" is not necessarily to be construed as preferred or advantageous over other implementations. All of the embodiments described below are exemplary embodiments provided to enable those skilled in the art to make and use examples of the disclosure and are not intended to limit the scope of the disclosure, which is defined by Claims limited. In other embodiments, well-known features and methods are described in detail so as not to obscure the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the drawings and described in the following description are simple exemplary embodiments of the inventive concepts defined in the appended claims. Therefore, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be two The internal communication of each element may be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms according to specific situations.

The "energy storage system" in this specification is one that stores generated electricity in various related systems including power stations, substations, and transmission lines and then selectively and efficiently uses the stored electricity as needed to improve energy efficiency The function of the system is to realize all-round monitoring and energy dispatching management of the working status of the energy storage power station. The energy storage system includes multiple battery packs, and each battery pack includes multiple battery cells connected in series or in parallel.

The full name of "SOC" in this manual is State of Charge, the state of charge, also called the remaining capacity, which represents the ratio of the remaining capacity of the battery after it has been used for a period of time or left unused for a long time to the capacity of the fully charged state, and the commonly used percentage express. Its value ranges from 0 to 1. When SOC=0, it means that the battery is completely discharged, and when SOC=1, it means that the battery is fully charged.

"Battery pack" in this manual has the same meaning as "battery pack" (PACK), including multiple cells connected in series and parallel.

Fig. 1 shows a kind of single-battery pack equalization control method, described battery pack comprises N cells, and this equalization control method comprises the following steps:

S11. Obtain the SOC of each of the N cells and the average SOC of the battery pack;

S12, controlling the cells whose SOC is greater than the average SOC of the battery pack to discharge the N cells of the battery pack.

In step S12 , the discharged electricity of the batteries whose SOC is greater than the average SOC of the battery pack is collected, and then the collected discharged electricity is charged to the N batteries of the battery pack.

Specifically, it is first necessary to calculate the SOC of each cell in the PACK. When the SOC of each cell is inconsistent, all cells higher than the average value can be discharged at the same time. By closing the switch of the corresponding cell position, the cell is discharged, the power is put on the entire PACK, and each cell on the PACK is charged. For example, there are N cells on each PACK, then each The energy obtained by a cell is 1/N of the energy released by a discharged cell. Repeating the cycle, you can put all the battery power higher than the average value of the SOC into all the battery cells lower than the average value, so that the power of each battery cell tends to be consistent around the average value. In this way, the purpose of power balance in the PACK is achieved.

Fig. 2 shows a battery pack balance control method for an energy storage system, the energy storage system includes a plurality of battery packs, each battery pack includes N cells, the balance control method includes the following steps:

S1, perform balanced control on each battery group of the energy storage system according to the above-mentioned single battery group balance control method;

S2. Obtain the SOC of each battery pack in the plurality of battery packs and the average SOC of the energy storage system;

S3, controlling the battery pack whose SOC is greater than the average SOC of the energy storage system to discharge the battery pack whose SOC is smaller than the average SOC of the energy storage system.

Further, in order to achieve power supply while the system is balancing, in step S3, the battery pack whose SOC is greater than the average SOC of the energy storage system discharges to the power supply circuit of the energy storage system, and the battery pack whose SOC is smaller than the average SOC of the energy storage system Charge from the power supply loop of the energy storage system.

Furthermore, in order to realize the auxiliary power supply function, in step S3, it is judged whether the current energy storage system is in an intermittent power supply state; The battery pack whose SOC is smaller than the average SOC of the energy storage system discharges to the power supply loop.

Specifically, when the SOCs in the PACKs are consistent, it is necessary to determine whether an equalization operation needs to be performed between the PACKs in the same system. First, it is necessary to obtain the SOC of each PACK in the system. When the SOC of one or more PACKs in the system is inconsistent with the average value of the system, the system needs to perform an equalization operation among the PACKs. By closing the switch between the corresponding PACK and the power supply loop, the PACK higher than the average value actively releases power to the power supply loop, and the PACK lower than the average value obtains power from the power supply loop, and the cycle goes on and on, so that all the PACKs tend to be close to the average value . To achieve the goal of consistent system SOC, please refer to Figure 3.

When the external power supply of the system is interrupted, through the low voltage judgment, the CPU can obtain the signal of the external power supply interruption. The output power can be used to supply power for the system. This process can also be carried out when the SOC between PACKs is unbalanced, and the battery pack whose SOC is greater than the average SOC of the energy storage system and the battery pack whose SOC is smaller than the average SOC of the energy storage system are controlled to the power supply circuit with different duty cycles. After discharging, the output power of the PACK with a large SOC value is relatively more than that of the PACK with a small SOC value. After a period of time, the SOC between the PACK and the PACK can reach the same level, as shown in Figure 4.

Correspondingly, an embodiment of the present invention provides a battery pack balancing control device for an energy storage system, as shown in FIG. 5 , the energy storage system includes multiple battery packs, for example, 12 battery packs C1- C12, each battery pack includes N batteries, and the balance control device includes: a single battery pack balance control component 10, charging and discharging components B1-B12, a detection component 20, a control component 30 and a voltage monitoring module 40, wherein the single battery The number of group balance control components 10 is 12, and the 12 single battery group balance control components 10 are set corresponding to the plurality of battery groups C1-C12, which perform balance control on a single battery group according to the control method shown in Figure 1 10. For its specific structure, please refer to FIG. 6 . The single battery pack balance control component 10 includes: a detection module 101 and a balance module 102. The detection module 101 is used to obtain the SOC of each battery cell in the N cells and the The average SOC of the battery pack, the balancing module 102 is used to control the cells whose SOC is greater than the average SOC of the battery pack to discharge the N cells of the battery pack; further, the balancing module 102 includes a charging and discharging unit 1021 and an electric power storage unit 1022 And the control unit 1023, wherein the charging and discharging unit 1021 is connected to the N battery cells respectively, and the number of the charging and discharging unit 1021 is N, which are set in one-to-one correspondence with the battery cells, and are used to charge and discharge the connected battery cells The power storage unit 1022 is connected to a plurality of charging and discharging units 1021 for storing electric power; the control unit 1023 is connected to the N cells for controlling the cells whose SOC is greater than the average SOC of the battery pack to store the power The unit 1022 discharges, and the power storage unit 1022 charges the N cells of the battery pack.

Please continue to refer to FIG. 5, the charging and discharging components B1-B12 are respectively connected to the plurality of battery packs C1-C12, and are used to charge and discharge the connected battery packs C1-C12, and the charging and discharging components B1-B12 respectively include The switch modules T1-T12 are used to connect or disconnect the power supply circuit of the energy storage system. The detection component 20 is used to obtain the SOC of each battery pack in the plurality of battery packs C1-C12 and the average SOC of the energy storage system. The control component 30 is connected to multiple charging and discharging components B1-B12, and is used to control the battery pack whose SOC is greater than the average SOC of the energy storage system to discharge to the power supply circuit of the energy storage system, and the battery pack whose SOC is smaller than the average SOC of the energy storage system to discharge from The power supply circuit of the energy storage system is charged. The voltage monitoring module 40 is connected with the power supply circuit, and is used for detecting the voltage of the power supply circuit and judging whether the current energy storage system is in a power supply interruption state according to the detected voltage; the control component 30 controls when the current energy storage system is in a power supply interruption state The battery packs C1-C12 discharge the power supply circuit. The control component 30 includes a PWM control module 301, which is used to control the battery pack whose SOC is greater than the average SOC of the energy storage system and the battery whose SOC is smaller than the average SOC of the energy storage system with different duty ratios when the energy storage system is in a power supply interruption state. At this time, the control unit 30 controls each of the battery packs C1-C12 to discharge to the power supply circuit, realizing the control of battery packs and SOCs whose SOC is greater than the average SOC of the energy storage system with different duty ratios. The battery pack with an SOC smaller than the average SOC of the energy storage system is discharged to the power supply circuit. For example, the connection between the battery pack with an SOC greater than the average SOC of the energy storage system and the power supply circuit is controlled with the first duty cycle, and the connection with the power supply circuit is controlled with the second duty cycle. Controlling the connection of the battery pack whose SOC is smaller than the average SOC of the energy storage system and the power supply circuit is on or off. In this embodiment, the control component 30 may be a single-chip microcomputer, and the single-chip microcomputer is an IC chip integrated with a CPU, a memory, an input and output interface, and the like.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. a kind of single battery group balance control method, the battery pack includes N number of battery core, it is characterised in that the Balance route side Method comprises the following steps：

S11, obtain each SOC of the battery core and average SOC of the battery pack in N number of battery core；

S12, the battery core for the average SOC that control SOC is more than battery pack are discharged N number of battery core of battery pack.

2. battery pack balancing control method according to claim 1, it is characterised in that in step s 12, it is big to collect SOC Collected discharge electricity amount is charged to N number of battery core of battery pack again in the discharge electricity amount of the average SOC of battery pack battery core.

3. a kind of energy-storage system battery pack balancing control method, the energy-storage system includes multiple battery packs, each battery pack bag Include N number of battery core, it is characterised in that the balance control method comprises the following steps：

S1, each battery pack of energy-storage system is carried out according to the single battery group balance control method described in claim 1 or 2 equal Weighing apparatus control；

S2, obtain the average SOC of the SOC of each battery pack and the energy-storage system in the multiple battery pack；

S3, control SOC are more than the average SOC of energy-storage system battery pack to battery packs of the SOC less than the average SOC of energy-storage system Discharged.

4. energy-storage system battery pack balancing control method according to claim 3, it is characterised in that in step s3, SOC Battery pack more than the average SOC of energy-storage system is discharged to the current supply circuit of energy-storage system, and SOC is less than being averaged for energy-storage system SOC battery pack charges from the current supply circuit of energy-storage system.

5. energy-storage system battery pack balancing control method according to claim 1, it is characterised in that in step s3, sentence Whether the current energy-storage system that breaks is in power supply interruption state；If it is, energy storage is more than with different Duty ratio control SOC respectively The battery pack that the average SOC of system battery pack and SOC is less than the average SOC of energy-storage system is discharged to current supply circuit.

6. a kind of energy-storage system cell balance control unit, the energy-storage system includes multiple battery packs, each battery pack bag Include N number of battery core, it is characterised in that the equalising control device includes：

The single battery group Balance route component being each correspondingly arranged with the multiple battery pack, including：For obtaining N number of electricity The SOC of each battery core and the average SOC detection modules of the battery pack and for controlling SOC to be more than the flat of battery pack in core The balance module that equal SOC battery core is discharged N number of battery core of battery pack；

The charge and discharge electrical component being each connected with the multiple battery pack, it is described for carrying out discharge and recharge to the battery pack connected Charge and discharge electrical component includes the switch module for being used to be switched on or switched off the current supply circuit of energy-storage system；

Detection components, for obtaining each SOC of battery pack and being averaged for the energy-storage system in the multiple battery pack SOC；And

The control assembly being all connected with multiple charge and discharge electrical components, for controlling SOC more than the average SOC of energy-storage system battery pack Current supply circuit electric discharge, SOC to energy-storage system are less than the average SOC of energy-storage system battery pack from the current supply circuit of energy-storage system Charging.

7. energy-storage system cell balance control unit according to claim 6, it is characterised in that the balance module bag Include：

The charge/discharge unit being each connected with N number of battery core, for carrying out discharge and recharge to the battery core connected；

The electricity storage element being connected with multiple charge/discharge units, for storing electricity；And

The control unit being all connected with N number of battery core, for controlling SOC more than the average SOC of battery pack battery core to described Electricity memory cell is discharged and the electricity memory cell is charged to N number of battery core of battery pack.

8. energy-storage system cell balance control unit according to claim 6, it is characterised in that the battery pack balancing Control device also includes the voltage monitoring module being connected with the current supply circuit, for detecting the voltage and root of the current supply circuit Judge current energy-storage system whether in power supply interruption state according to detected voltage.

9. energy-storage system cell balance control unit according to claim 8, it is characterised in that the control assembly bag PWM control modules are included, for being more than storage respectively with different Duty ratio control SOC when energy-storage system is in power supply interruption state The average SOC of energy system battery pack and SOC is less than the average SOC battery pack of energy-storage system and the connection of current supply circuit is led to It is disconnected.

10. energy-storage system cell balance control unit according to claim 6, it is characterised in that the control assembly For single-chip microcomputer.