Unipolar battery equalization method and device for energy storage system

Abstract

The embodiment of the invention discloses a unipolar battery equalization method and device for an energy storage system. The unipolar battery equalization method comprises the steps of calculating a state-of-charge value of each single battery according to a sampling value of an electrical basic physical quantity; calculating a difference value between the state-of-charge value of each single battery and an average state-of-charge value of a battery pack to which the single battery belongs; determining the single batteries of which the difference values exceed a preset equalization threshold value as unbalanced batteries; and switching on a selection switch corresponding to the unbalanced battery so as to enable the unbalanced battery to be connected with a primary side port of the multi-port converter, and setting the working state of the multi-port converter as the balanced electric quantity of the unbalanced battery. By adopting the embodiment of the invention, energy storage elements required in a multi-pole framework can be reduced, the integration level is higher, the system is simpler, the reliability of the system can be improved, and the hardware cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage battery balancing control, and in particular to a monopolar battery balancing method and related devices for an energy storage system. Background Art

[0002] With the continuous advancement of science and technology, battery technology has achieved remarkable development in many fields. Common types of batteries such as lithium-ion batteries and lead-acid batteries have achieved different degrees of improvement in energy density, charge and discharge efficiency, cycle life, etc. These batteries are widely used in the construction of energy storage systems, and are connected in series and parallel to form battery packs to meet the diverse requirements of energy storage systems for voltage, power and energy storage capacity in different application scenarios. However, in the actual application of battery packs, the performance differences between battery cells often lead to imbalance in the system. There are many factors that affect battery imbalance, including battery manufacturing differences, aging effects, and changes in working environment temperature. These factors not only lead to differences in the charge and discharge states of single cells, but may also cause a decline in the overall performance of the battery pack, and even affect the safety and service life of the system. Therefore, in view of the performance imbalance problem existing in the battery pack, it is particularly important to use effective battery balancing technology to manage and optimize the battery pack.

[0003] Traditional battery balancing methods have certain limitations, especially when achieving simultaneous charging and balancing of multiple batteries, a multi-pole structure is often required, such as the patent with publication number "CN117791814A" and name "Energy Storage Battery Balancing Circuit and Method, Energy Storage Battery Balancer". Although this multi-pole architecture can achieve battery balancing, it also brings many problems, including a large number of energy storage components required, low integration, complex system, poor reliability and high cost. These shortcomings limit the widespread application of traditional balancing methods in large-scale battery systems. Summary of the invention

[0004] The embodiments of the present application provide a unipolar battery balancing method and related devices for an energy storage system, which are beneficial to reducing the energy storage elements required in a multipolar architecture, have a higher degree of integration and a simpler system, and can improve system reliability and reduce hardware costs.

[0005] In a first aspect, an embodiment of the present application provides a unipolar battery balancing method for an energy storage system, wherein the energy storage system comprises m battery packs connected in series, each of the battery packs comprises n single cells connected in series, the positive and negative electrodes of each single cell are respectively connected to the positive and negative electrodes of a primary port of a multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the first single cell of the first battery pack, and the negative electrode of the secondary port of the multi-port converter is connected to the nth single cell of the mth battery pack, wherein m and n are both integers greater than 0; the method comprises: Calculating the state of charge value of each of the single cells according to the sampled values ​​of the electrical basic physical quantities; Calculating the difference between the state of charge value of each of the single cells and the average state of charge value of the battery pack to which the single cell belongs; Determine the single battery whose difference exceeds the preset balancing threshold as an unbalanced battery; The selection switch corresponding to the unbalanced battery is turned on to connect the unbalanced battery to the primary port of the multi-port converter, and the working state of the multi-port converter is set to balance the power of the unbalanced battery.

[0006] Exemplarily, setting the working state of the multi-port converter to the unbalanced battery balanced power includes: If the difference is greater than 0, setting the working state of the multi-port converter to a discharge state in which the unbalanced battery is discharged; If the difference is less than 0, the working state of the multi-port converter is set to a charging state to charge the unbalanced battery.

[0007] Exemplarily, the step of turning on the selection switch corresponding to the unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter includes: If the battery pack includes one or more unbalanced batteries that are not directly connected in series, turning on two selection switches corresponding to each unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter; If the battery pack includes a plurality of unbalanced batteries directly connected in series, the selection switch corresponding to the positive electrode of the first unbalanced battery and the selection switch corresponding to the negative electrode of the last unbalanced battery are turned on so that the unbalanced battery is connected to the primary port of the multi-port converter, and the first and last unbalanced batteries are respectively the first and last of the plurality of unbalanced batteries directly connected in series.

[0008] Exemplarily, the calculating the state of charge value of each of the single cells according to the sampled value of the electrical basic physical quantity includes: If the electrical basic physical quantity is voltage, the state of charge value of each of the single cells is calculated according to one of the voltage method, the open circuit voltage method, and the cumulative power integration method and the sampled value of the voltage; or, If the basic electrical physical quantities are current and voltage, the state of charge value of each of the single cells is calculated according to the Kalman filter method and the sampled values ​​of the current and the voltage.

[0009] A second aspect of an embodiment of the present application provides a unipolar battery balancing device for an energy storage system, wherein the energy storage system comprises m battery packs connected in series, each of the battery packs comprises n single cells connected in series, the positive and negative electrodes of each single cell are respectively connected to the positive and negative electrodes of a primary port of a multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the first single cell of the first battery pack, and the negative electrode of the secondary port of the multi-port converter is connected to the nth single cell of the mth battery pack, wherein m and n are both integers greater than 0; the device comprises: A state of charge calculation unit, used to calculate the state of charge value of each of the single cells according to the sampled values ​​of the electrical basic physical quantities; A charge difference calculation unit, used for calculating the difference between the state of charge value of each of the single cells and the average state of charge value of the battery pack to which the single cell belongs; An unbalanced battery determination unit, configured to determine a single battery whose difference exceeds a preset equalization threshold as an unbalanced battery; The power balancing unit is used to turn on the selection switch corresponding to the unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter, and to set the working state of the multi-port converter to balance the power of the unbalanced battery.

[0010] A third aspect of the embodiments of the present application provides a unipolar battery balancing system for an energy storage system, wherein the unipolar battery balancing system includes an energy storage system, a switch array, a multi-port converter, and a controller; The energy storage system comprises m battery packs connected in series, each of the battery packs comprises n single cells connected in series, the positive and negative electrodes of each single cell are respectively connected to the positive and negative electrodes of a primary port of the multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the positive electrode of the first single cell of the first battery pack, and the negative electrode of the secondary port of the multi-port converter is connected to the negative electrode of the nth single cell of the mth battery pack, wherein m and n are both integers greater than 0; the switch array is composed of 2mn selection switches; The controller calculates the state of charge value of each single cell by sampling the value of the basic electrical physical quantity; calculates the difference between the state of charge value of each single cell and the average state of charge value of the battery group to which the single cell belongs; determines the single cell whose difference exceeds a preset balancing threshold as an unbalanced cell; turns on the selection switch corresponding to the unbalanced cell so that the unbalanced cell is connected to the primary port of the multi-port converter, and sets the working state of the multi-port converter to the balanced power of the unbalanced cell.

[0011] Exemplarily, if the electrical basic physical quantity is voltage, the unipolar battery balancing system further includes a voltage monitoring circuit, and the controller obtains the voltage sampling value through the voltage monitoring circuit; or, If the electrical basic physical quantity is current, the monopolar battery balancing system further includes a current monitoring circuit, and the controller obtains the current sampling value through the current monitoring circuit; or, If the electrical basic physical quantities are current and voltage, the monopolar battery balancing system further includes a current monitoring circuit and a voltage monitoring circuit, and the controller obtains the current sampling value through the current monitoring circuit and obtains the voltage sampling value through the voltage monitoring circuit.

[0012] Exemplarily, the multi-port converter includes at least one of the following: a full-bridge topology multi-port converter, an LLC resonant multi-port converter, a CLLC resonant multi-port converter, a flyback multi-port converter, and a forward multi-port converter.

[0013] A fourth aspect of the embodiments of the present application provides an electronic device, including: a processor and a memory; The processor is connected to the memory, wherein the memory is used to store a computer program, and the processor is used to call the computer program to execute the method in the first aspect of the embodiment of the present application.

[0014] A fifth aspect of an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. The computer program includes program instructions. When the program instructions are executed by a processor, the method in the first aspect of the embodiment of the present application is executed.

[0015] In the present application, the positive and negative electrodes of each single cell of the energy storage system are respectively connected to the positive and negative electrodes of a primary port of the multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the first single cell of the first battery group, and the negative electrode of the secondary port is connected to the nth single cell of the mth battery group, so that the position of the unbalanced battery can be judged by the charge state of the battery, and the corresponding selection switch is turned on so that the primary side of the multi-port converter can be connected, and then the working state of the multi-port converter is set to unbalanced battery equalization, thereby achieving unipolar battery power balancing; relative to the multi-pole architecture disclosed in the patent with publication number "CN117791814A" and name "Energy Storage Battery Equalization Circuit and Method, Energy Storage Battery Equalizer", n single cells require n / 2 inductors and n-1 capacitors, and the present application greatly reduces energy storage elements such as inductors and capacitors. Therefore, the present application has a higher degree of integration and a simpler system, which can improve the reliability of the system and reduce hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of a monopolar battery balancing system for an energy storage system provided by an embodiment of the present application is shown; Figure 2 A schematic diagram of a flow chart of a monopolar battery balancing method for an energy storage system provided by an embodiment of the present application is shown; Figure 3 A schematic diagram of equalization of a single overcharged battery provided by an embodiment of the present application is shown; Figure 4 A schematic diagram of equalization of a single undercharged battery provided by an embodiment of the present application is shown; Figure 5 A schematic diagram of equalization of multiple overcharged batteries provided by an embodiment of the present application is shown; Figure 6 A schematic diagram of equalization of multiple undercharged batteries provided by an embodiment of the present application is shown; Figure 7 A schematic diagram of the structure of a monopolar battery balancing device for an energy storage system provided by an embodiment of the present application is shown; Figure 8 A schematic diagram of the structure of a computer device provided in one embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] Please refer to Figure 1 , which shows a schematic diagram of a monopolar battery balancing system for an energy storage system provided by an embodiment of the present application. The monopolar battery balancing system for an energy storage system may include: an energy storage system 10, a switch array 20, a multi-port converter 30 and a controller 40.

[0020] The energy storage system 10 includes m battery packs connected in series, each battery pack includes n single batteries connected in series. , where i ranges from 1 to m and j ranges from 1 to n. For example, the battery pack Including n single cells , battery pack Including n single cells ,···,battery pack Including n single cells , m and n are both integers greater than 0.

[0021] Each single battery The positive terminal is connected through a selector switch A primary port of the multi-port converter 30 The positive connection of each single battery The negative pole is connected through a selector switch A primary port of the multi-port converter 30 The negative electrode of each battery pack is connected. Each battery pack may share a primary port or may not share a primary port, which is not limited here. Figure 1 Figure 2 shows the case where each battery pack can share one primary port. Figure 1 As shown, The positive electrode passes With the multi-port converter 30 The positive connection of The negative electrode passes With the multi-port converter 30 The negative connection of The positive electrode passes With the multi-port converter 30 The positive connection of The negative electrode passes With the multi-port converter 30 The negative connection of The positive electrode passes With the multi-port converter 30 The positive connection of The negative electrode passes With the multi-port converter 30 Negative connection of battery pack Share one primary port , the rest of the reference Figure 1 And this example. I won't list them one by one here.

[0022] The secondary port of the multi-port converter 30 The positive terminal of the first battery pack The first single cell The positive electrode of the multi-port converter 30 is connected to the secondary port The negative electrode of the mth battery pack The nth single cell negative connection.

[0023] The switch array 20 consists of 2mn selection switches ( , ··· , , ··· ,······, , ··· , , ··· , , ··· ,······, , ··· )composition.

[0024] The controller 40 is a device for controlling and managing the operation of a system or device. It can receive input signals, process them according to preset rules and algorithms, and output control signals to adjust the working state of the system or device. In the present application, the controller 40 calculates the state of charge value of each single cell by sampling the value of the basic electrical physical quantity; calculates the difference between the state of charge value of each single cell and the average state of charge value of the battery group to which the single cell belongs; determines the single cell whose difference exceeds the preset balancing threshold as an unbalanced cell; turns on the selection switch corresponding to the unbalanced cell so that the unbalanced cell is connected to the primary port of the multi-port converter 30. , and setting the working state of the multi-port converter 30 to unbalanced battery balancing power.

[0025] Exemplarily, if the basic electrical physical quantity is voltage, the unipolar battery balancing system further includes a voltage monitoring circuit 60, and the controller 40 obtains a voltage sampling value through the voltage monitoring circuit 60; or, If the basic electrical physical quantity is current, the unipolar battery balancing system further includes a current monitoring circuit 70, and the controller obtains a current sampling value through the current monitoring circuit 70; or, If the basic electrical physical quantities are current and voltage, the unipolar battery balancing system further includes a current monitoring circuit 70 and a voltage monitoring circuit 60 . The controller obtains a current sampling value through the current monitoring circuit 70 , and obtains a voltage sampling value through the voltage monitoring circuit 60 .

[0026] Furthermore, the voltage monitoring circuit 60 and the current monitoring circuit 70 can communicate with the controller 40 through a network, and the voltage monitoring circuit 60 and the current monitoring circuit 70 can be directly or indirectly connected to the controller 40 through wired or wireless communication, so that the voltage value sampled by the voltage monitoring circuit 60 and / or the current value sampled by the current monitoring circuit 70 are transmitted to the controller 40, and the present application does not impose any restrictions here.

[0027] Furthermore, the unipolar battery balancing system also includes a drive circuit 50 connected to the controller 40. The controller 40 can realize the closing or opening of 2mn selection switches through the drive signal generated by the drive circuit 50. The controller 40 can also realize the setting of the working state of the multi-port converter 30 through the drive signal generated by the drive circuit 50.

[0028] Exemplarily, the multi-port converter may include at least one of the following: a full-bridge topology multi-port converter, an LLC resonant multi-port converter, a CLLC resonant multi-port converter, a flyback multi-port converter, and a forward multi-port converter.

[0029] Exemplarily, the selection switch may be a mechanical switch, a relay switch, an electronic switch, a switch tube or other types of switches. In one embodiment of the present application, the selection switch of the present application is a relay switch. Thus, compared with the switch tube in the prior art, the cost of the relay switch of the present application is lower.

[0030] It can be seen that in the unipolar battery balancing system for the energy storage system provided in the present application, the positive and negative electrodes of each single cell of the energy storage system are respectively connected to the positive and negative electrodes of a primary port of the multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the first single cell of the first battery group, and the negative electrode of the secondary port is connected to the nth single cell of the mth battery group, so that the position of the unbalanced battery can be judged by the charge state of the battery, and the corresponding selection switch is turned on so that the primary side of the multi-port converter can be connected, and then the working state of the multi-port converter is set to the unbalanced battery balancing power, thereby realizing the unipolar battery power balancing; relative to the multi-polar architecture disclosed in the patent with the publication number of "CN117791814A" and the name of "Energy Storage Battery Balancing Circuit and Method, Energy Storage Battery Balancer", n single cells require n / 2 inductors and n-1 capacitors, and the energy storage elements such as inductors and capacitors are greatly reduced in the present application. Therefore, the present application has a higher degree of integration and a simpler system, which can improve the reliability of the system and reduce the hardware cost.

[0031] Please refer to Figure 2 , which shows a schematic flow chart of a monopolar battery balancing method for an energy storage system provided by an embodiment of the present application. The method can be applied to Figure 1 The unipolar battery balancing system for energy storage system shown in FIG. The execution subject of each step can be Figure 1 The controller 40 shown. The method may include the following steps: Step 201: Calculate the state of charge value of each single battery according to the sampled values ​​of the basic electrical physical quantities.

[0032] Among them, the state of charge (SOC) is used to reflect the remaining power of the battery, usually expressed as a percentage.

[0033] Specifically, the step of calculating the state of charge value of each single battery according to the sampled value of the basic electrical physical quantity includes: If the basic electrical physical quantity is voltage, the state of charge value of each single battery is calculated according to one of the voltage method, open circuit voltage method, cumulative power integration method and the voltage sampling value; or, If the basic electrical physical quantities are current and voltage, the state of charge value of each single battery is calculated based on the Kalman filter method and the sampled values ​​of current and voltage.

[0034] Among them, for the voltage method, the SOC is determined according to the following formula: SOC=(current voltage sampling value-minimum voltage value) / (maximum voltage value-minimum voltage value), and the maximum voltage value and the minimum voltage value are set according to the actual situation of the battery.

[0035] Among them, for the open circuit voltage method, the SOC is calculated based on the relationship between the battery open circuit voltage and the SOC. The relationship between the battery open circuit voltage and the SOC is a special function, which needs to be determined according to the type of battery.

[0036] Among them, for the cumulative power integration method, first obtain the sampled actual battery voltage value and the battery rated voltage value, then calculate the battery current power according to the actual battery voltage value, calculate the battery rated power according to the battery rated voltage value, and determine the SOC according to the ratio of the battery current power to the battery rated power.

[0037] Among them, the Kalman filter method is a method for calculating SOC based on battery current, voltage and other information. It uses state estimation and Kalman filter technology. The specific implementation process is relatively complicated and requires the use of mathematical models and computer algorithms.

[0038] Step 202: Calculate the difference between the state of charge value of each single cell and the average state of charge value of the battery group to which the single cell belongs.

[0039] The average state of charge value of a battery pack can be determined by summing the state of charge values ​​of all the cells included in the battery pack and then dividing by the number of cells included in the battery pack. Any single cell in the battery pack belongs to the battery pack The average state of charge value of the battery pack is also The average state of charge value of the battery pack The average state of charge value can be obtained by The state of charge values ​​are summed and then divided by n.

[0040] Step 203: Determine the single cells whose difference exceeds the preset balancing threshold as unbalanced cells.

[0041] The preset equalization threshold is predetermined, for example, the preset equalization threshold may be ±1%, ±2%, ±5% of the average state of charge value of the battery pack, or other values, which are not limited here. For example, if the average state of charge value of the battery pack is 80%, if the preset equalization threshold is ±1%, then the single cells below 79.2% or above 80.8% are determined to be unbalanced cells; if the preset equalization threshold is ±2%, then the single cells below 78.4% or above 81.6% are determined to be unbalanced cells.

[0042] Step 204: Turn on the selection switch corresponding to the unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter, and set the working state of the multi-port converter to balance the power of the unbalanced battery.

[0043] Each single cell Corresponding to two selector switches and , which can be to turn on the corresponding selection switch , or it can be to turn on the corresponding selection switch , or it can turn on the corresponding selection switch and , no limitation is made here.

[0044] The working state of the multi-port converter can be a discharge state or a charge state. If the difference is greater than 0, the working state of the multi-port converter is set to the discharge state as unbalanced battery discharge; if the difference is less than 0, the working state of the multi-port converter is set to the charge state as unbalanced battery charge.

[0045] It can be seen that in the unipolar battery balancing method for energy storage systems provided in the present application, the unbalanced battery in the battery pack is judged by comparing the charge state value of the single cell with the average charge state value of the group to which it belongs, so as to turn on the corresponding selection switch to connect to the multi-port converter to form a loop, and then set the working state of the multi-port converter to charge or discharge it to balance its charge, thereby achieving the balance of charge inside the battery pack, which is beneficial to improving the overall performance of the battery pack and improving the safety and service life of the system.

[0046] Furthermore, after the single cells in each battery pack are all charged equally, the method further includes: determining a state of charge value for each battery pack; Calculate the difference between the state of charge value of each battery group and the average state of charge value of the m battery groups; Determine a battery pack whose difference exceeds a preset balancing threshold as an unbalanced battery pack; The selection switch corresponding to the unbalanced battery group is turned on to connect the unbalanced battery group to the primary port of the multi-port converter, and the working state of the multi-port converter is set to balance the power of the unbalanced battery group.

[0047] The power balancing method of the unbalanced battery pack refers to the power balancing method of the unbalanced battery mentioned above, which will not be described in detail here. It can be seen that the embodiment of the present application can not only achieve power balancing of the single cells inside the battery pack, but also achieve power balancing of the battery pack, thereby improving the integration and reliability of the system.

[0048] In one embodiment of the present application, if the battery pack includes one or more unbalanced batteries that are not directly connected in series, and the difference between the state of charge value of the unbalanced battery and the average state of charge value of the battery pack to which it belongs is greater than 0, then the two selection switches corresponding to each unbalanced battery are turned on so that the unbalanced battery is connected to the primary port of the multi-port converter, and the working state of the multi-port converter is set to the discharge state for the unbalanced battery discharge.

[0049] If the battery pack includes one or more unbalanced batteries that are not directly connected in series, and the difference between the state of charge value of the unbalanced battery and the average state of charge value of the battery pack to which it belongs is less than 0, then the two selection switches corresponding to each unbalanced battery are turned on so that the unbalanced battery is connected to the primary port of the multi-port converter, and the working state of the multi-port converter is set to the charging state for charging the unbalanced battery.

[0050] Battery Pack There is an unbalanced battery and battery pack There is an unbalanced battery For example. If SOC and If the difference in the average SOC is greater than 0, it means that the battery is unbalanced. For overcharged batteries, discharge is required, so the working state of the multi-port converter should be set to discharge state. SOC and If the difference in the average SOC is less than 0, it means that the battery is unbalanced. For undercharged batteries, they need to be charged, so the working state of the multi-port converter should be set to charging state. The judgment of whether it is an overcharged battery or an undercharged battery can also be based on its The positive or negative value of the difference in the average SOC is determined, and then if it is overcharged, the working state of the multi-port converter is set to the discharging state, and if it is undercharged, the working state of the multi-port converter is set to the charging state.

[0051] like Figure 3 and Figure 4 As shown, Figure 3 A schematic diagram of equalization of a single overcharged battery provided by an embodiment of the present application is shown. Figure 4 A schematic diagram of equalization of a single under-charged battery provided by an embodiment of the present application is shown. Figure 3 , close the selector switch and , and , Connect to the primary side of the multiport converter , Connect to the primary side of the multiport converter , setting the multi-port converter in discharge mode, the energy is released to the secondary side and fed back to the long series battery pack. Figure 4 In the same way, close the selector switch and , and , Connect to the primary side of the multiport converter , Connect to the primary side of the multiport converter , set the multi-port converter to charging mode, and the battery pack is connected to the secondary side of the multi-port converter. and Charging is performed to increase its SOC value to the required level.

[0052] It should be noted that Figure 3 and Figure 4 Shows the battery pack The above only includes the overcharge and undercharge equalization of one unbalanced battery. For the case of multiple unbalanced batteries that are not directly connected in series, you can also refer to Figure 3 and Figure 4 , such as battery packs Including unbalanced batteries , , , you need to close the selector switch and , and , and , the rest of the situation is the same.

[0053] It can be seen that in the embodiment of the present application, different battery groups corresponding to each port of the multi-port converter can be balanced at the same time, which greatly improves the balancing speed and shortens the balancing time.

[0054] In one embodiment of the present application, if the battery pack includes a plurality of unbalanced batteries directly connected in series and the difference between the state of charge value of the unbalanced battery and the average state of charge value of the battery pack to which it belongs is greater than 0, the selection switch corresponding to the positive electrode of the first unbalanced battery and the selection switch corresponding to the negative electrode of the last unbalanced battery are turned on so that the unbalanced battery is connected to the primary port of the multi-port converter, and the working state of the multi-port converter is set to the discharge state for the unbalanced battery discharge.

[0055] If the battery pack includes a plurality of unbalanced batteries directly connected in series and the difference between the state of charge value of the unbalanced battery and the average state of charge value of the battery pack to which it belongs is less than 0, the selection switch corresponding to the positive electrode of the first unbalanced battery and the selection switch corresponding to the negative electrode of the last unbalanced battery are turned on so that the unbalanced battery is connected to the primary port of the multi-port converter, and the working state of the multi-port converter is set to the charging state for charging the unbalanced battery.

[0056] The first and the last unbalanced battery are respectively the first and the last of a plurality of unbalanced batteries directly connected in series.

[0057] Battery Pack There is an unbalanced battery and , battery pack There is an unbalanced battery and For example. If and SOC and If the difference in the average SOC is greater than 0, it means that the battery is unbalanced. and For overcharged batteries, discharge is required, so the working state of the multi-port converter should be set to discharge state. and SOC and If the difference in the average SOC is less than 0, it means that the battery is unbalanced. and For undercharged batteries, they need to be charged, so the working state of the multi-port converter should be set to charging state. and The judgment of whether it is an overcharged battery or an undercharged battery can also be based on its The positive or negative value of the difference in the average SOC is determined, and then if it is overcharged, the working state of the multi-port converter is set to the discharging state, and if it is undercharged, the working state of the multi-port converter is set to the charging state.

[0058] like Figure 5 and Figure 6 As shown, Figure 5 A schematic diagram of equalization of multiple overcharged batteries provided by an embodiment of the present application is shown. Figure 6 A schematic diagram of equalization of multiple undercharged batteries provided by an embodiment of the present application is shown. Figure 5 , close the selector switch and , and , and Connect to the primary side of the multiport converter , and Connect to the primary side of the multiport converter , setting the multi-port converter in discharge mode, the energy is released to the secondary side and fed back to the long series battery pack. Figure 6 In the same way, close the selector switch and , and , and Connect to the primary side of the multiport converter , and Connect to the primary side of the multiport converter , set the multi-port converter to charging mode, and the battery pack is connected to the secondary side of the multi-port converter. and , and Charging is performed to increase its SOC value to the required level.

[0059] It should be noted that Figures 3 to 6 The multi-port converter in the full-bridge topology is taken as an example, and can also be based on Figure 1 In the embodiment, other types of multi-port converters are used; similarly, the equalization method of overcharging or undercharging of a single or multiple unbalanced battery packs can also be referred to. Figures 3 to 6 , I will not give examples one by one here.

[0060] It can be seen that in the embodiment of the present application, based on the previous embodiment, not only can the simultaneous balancing of unbalanced batteries in different battery groups be achieved, but also the simultaneous balancing of different unbalanced batteries in the same battery group can be achieved, which further improves the balancing speed and shortens the balancing time.

[0061] Figure 7 The structure diagram of a monopolar battery balancing device for an energy storage system provided by an embodiment of the present application is shown. The device can be applied to Figure 1 The single-pole battery balancing system for energy storage system shown in the figure includes: A state of charge calculation unit 701, configured to calculate the state of charge value of each of the single cells according to the sampled values ​​of the electrical basic physical quantities; A charge difference calculation unit 702, used for calculating the difference between the state of charge value of each single cell and the average state of charge value of the battery group to which the single cell belongs; An unbalanced battery determination unit 703, configured to determine a single battery whose difference exceeds a preset balancing threshold as an unbalanced battery; The power balancing unit 704 is used to turn on the selection switch corresponding to the unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter, and to set the working state of the multi-port converter to balance the power of the unbalanced battery.

[0062] Figure 8 A schematic diagram of the structure of a computer device provided in one embodiment of the present application is shown, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the functions of the computer system of the monopolar battery balancing method for the energy storage system in any of the above-mentioned embodiments are implemented.

[0063] The present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a computer, the computer performs the functions of the computer system of the monopolar battery balancing method for an energy storage system in any of the above-mentioned embodiments.

[0064] The embodiments of the present application also provide a computer program product including instructions, which, when executed by a computer, enables the computer to perform the functions of the computer system of the monopolar battery balancing method for an energy storage system in any of the above embodiments.

[0065] It should be understood that the specific examples in this application are only intended to help those skilled in the art to better understand the embodiments of the present application, rather than to limit the scope of the present invention.

[0066] It can be understood that in the various implementations of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present application.

[0067] It can be understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited to this.

[0068] Unless otherwise stated, all technical and scientific terms used in the embodiments of the present application have the same meaning as those generally understood by those skilled in the art of the technical field of the present application. The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the scope of the present application. The term "and / or" used in the present application includes any and all combinations of one or more related listed items. The singular forms of "a kind of", "above" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0069] It can be understood that the controller 40 of the embodiment of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method implementation can be completed by the hardware integrated logic circuit in the processor or the instruction in the form of software. The above processor can be a general processor, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiment of the present application can be implemented or executed. The general processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to perform, or the hardware and software modules in the decoding processor are combined to perform. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0070] It is understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (programmable ROM, PROM), an erasable programmable read-only memory (erasable PROM, EPROM), an electrically erasable programmable read-only memory (EEPROM) or a flash memory. The volatile memory may be a random access memory (RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0071] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0072] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method implementation methods and will not be repeated here.

[0073] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device implementation described above is only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0074] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0075] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0076] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of each implementation method of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0077] The above are only specific embodiments of the present application, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A monopolar battery balancing method for an energy storage system, characterized in that: The energy storage system comprises m battery packs connected in series, each of the battery packs comprises n single cells connected in series, the positive and negative electrodes of each single cell are respectively connected to the positive and negative electrodes of a primary port of a multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the first single cell of the first battery pack, and the negative electrode of the secondary port of the multi-port converter is connected to the nth single cell of the mth battery pack, wherein m and n are both integers greater than 0; the method comprises: Calculating the state of charge value of each of the single cells according to the sampled values ​​of the electrical basic physical quantities; Calculating the difference between the state of charge value of each of the single cells and the average state of charge value of the battery pack to which the single cell belongs; Determine the single battery whose difference exceeds the preset balancing threshold as an unbalanced battery; The selection switch corresponding to the unbalanced battery is turned on to connect the unbalanced battery to the primary port of the multi-port converter, and the working state of the multi-port converter is set to balance the power of the unbalanced battery.

2. The method according to claim 1, characterized in that The step of setting the working state of the multi-port converter to the unbalanced battery balanced power comprises: If the difference is greater than 0, setting the working state of the multi-port converter to a discharge state in which the unbalanced battery is discharged; If the difference is less than 0, the working state of the multi-port converter is set to a charging state to charge the unbalanced battery.

3. The method according to claim 2, characterized in that The step of turning on the selection switch corresponding to the unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter includes: If the battery pack includes one or more unbalanced batteries that are not directly connected in series, turning on two selection switches corresponding to each unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter; If the battery pack includes a plurality of unbalanced batteries directly connected in series, the selection switch corresponding to the positive electrode of the first unbalanced battery and the selection switch corresponding to the negative electrode of the last unbalanced battery are turned on so that the unbalanced battery is connected to the primary port of the multi-port converter, and the first and last unbalanced batteries are respectively the first and last of the plurality of unbalanced batteries directly connected in series.

4. The method according to any one of claims 1 to 3, characterized in that: The step of calculating the state of charge value of each of the single cells according to the sampled value of the basic electrical physical quantity comprises: If the electrical basic physical quantity is voltage, the state of charge value of each of the single cells is calculated according to one of the voltage method, the open circuit voltage method, and the cumulative power integration method and the sampled value of the voltage; or, If the basic electrical physical quantities are current and voltage, the state of charge value of each of the single cells is calculated according to the Kalman filter method and the sampled values ​​of the current and the voltage.

5. A monopolar battery balancing device for an energy storage system, characterized in that: The energy storage system comprises m battery packs connected in series, each of which comprises n single cells connected in series, the positive and negative electrodes of each single cell are respectively connected to the positive and negative electrodes of a primary port of a multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the first single cell of the first battery pack, and the negative electrode of the secondary port of the multi-port converter is connected to the nth single cell of the mth battery pack, wherein m and n are both integers greater than 0; the device comprises: A state of charge calculation unit, used to calculate the state of charge value of each of the single cells according to the sampled values ​​of the electrical basic physical quantities; A charge difference calculation unit, used for calculating the difference between the state of charge value of each of the single cells and the average state of charge value of the battery pack to which the single cell belongs; An unbalanced battery determination unit, configured to determine a single battery whose difference exceeds a preset equalization threshold as an unbalanced battery; The power balancing unit is used to turn on the selection switch corresponding to the unbalanced battery so that the unbalanced battery is connected to the primary port of the multi-port converter, and to set the working state of the multi-port converter to balance the power of the unbalanced battery.

6. A monopolar battery balancing system for an energy storage system, characterized in that: The monopolar battery balancing system includes an energy storage system, a switch array, a multi-port converter and a controller; The energy storage system comprises m battery packs connected in series, each of the battery packs comprises n single cells connected in series, the positive and negative electrodes of each single cell are respectively connected to the positive and negative electrodes of a primary port of the multi-port converter through a selection switch, the positive electrode of the secondary port of the multi-port converter is connected to the positive electrode of the first single cell of the first battery pack, and the negative electrode of the secondary port of the multi-port converter is connected to the negative electrode of the nth single cell of the mth battery pack, wherein m and n are both integers greater than 0; the switch array is composed of 2mn selection switches; The controller calculates the state of charge value of each of the single cells through the sampling value of the electrical basic physical quantity; Calculating the difference between the state of charge value of each of the single cells and the average state of charge value of the battery pack to which the single cell belongs; The single cell whose difference exceeds the preset balancing threshold is determined as an unbalanced cell; the selection switch corresponding to the unbalanced cell is turned on so that the unbalanced cell is connected to the primary port of the multi-port converter, and the working state of the multi-port converter is set to the balanced power of the unbalanced cell.

7. The monopolar battery equalization system according to claim 6, characterized in that: If the electrical basic physical quantity is voltage, the monopolar battery balancing system further includes a voltage monitoring circuit, and the controller obtains the voltage sampling value through the voltage monitoring circuit; or, If the electrical basic physical quantity is current, the monopolar battery balancing system further includes a current monitoring circuit, and the controller obtains the current sampling value through the current monitoring circuit; or, If the electrical basic physical quantities are current and voltage, the monopolar battery balancing system further includes a current monitoring circuit and a voltage monitoring circuit, and the controller obtains the current sampling value through the current monitoring circuit and obtains the voltage sampling value through the voltage monitoring circuit.

8. The monopolar battery equalization system according to claim 6 or 7, characterized in that: The multi-port converter includes at least one of the following: a full-bridge topology multi-port converter, an LLC resonant multi-port converter, a CLLC resonant multi-port converter, a flyback multi-port converter, and a forward multi-port converter.

9. An electronic device, characterized in that: include: Processor and memory; The processor is connected to a memory, wherein the memory is used to store a computer program, and the processor is used to call the computer program to execute the method according to any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, wherein the computer program includes program instructions, and when the program instructions are executed by a processor, the method according to any one of claims 1 to 4 is executed.

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