Battery pack

Abstract

A battery pack includes a first battery rack, a first power conversion circuit, a second battery rack, and a battery controller. The first battery rack is connected between a first set of terminals and a second set of terminals of the battery pack. The first power conversion circuit includes a first terminal, a second terminal, a third terminal, and a fourth terminal connected to the second group of terminals. And the first power conversion circuit is configured to bidirectionally convert a first conversion voltage between the first terminal and the second terminal into a second conversion voltage between the third terminal and the fourth terminal. The second battery rack is connected between the first group of terminals and a third terminal of the first power conversion circuit. The battery controller is configured to control the first power conversion circuit to adjust a level of the second conversion voltage.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0035361 filed in the Korean Intellectual Property Office on March 13, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] One or more embodiments relate to a battery pack, and more particularly, to a battery pack in which a plurality of battery racks are connected in parallel to each other using a power conversion circuit. Background Art

[0004] Unlike non-rechargeable primary batteries, secondary batteries are rechargeable. Small secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large secondary batteries are widely used in hybrid vehicles, electric vehicles, and energy storage systems. Typically, large batteries consist of battery cells, battery modules, battery racks, and battery packs.

[0005] This information regarding the related art is merely for facilitating understanding of the background of the present disclosure and therefore may contain information that does not constitute related art. Summary of the Invention

[0006] One or more embodiments include a battery pack in which multiple battery racks may be connected in parallel with each other using low-capacity power conversion circuitry.

[0007] However, the present disclosure is not limited thereto and will be apparently understood by those skilled in the art through the following description.

[0008] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0009] According to one or more embodiments, a battery pack includes a first battery rack, a first power conversion circuit, a second battery rack, and a battery controller. The first battery rack is connected between a first set of terminals and a second set of terminals of the battery pack. The first power conversion circuit includes a first terminal, a second terminal, a third terminal, and a fourth terminal connected to the second set of terminals. The first power conversion circuit is configured to bidirectionally convert a first conversion voltage between the first terminal and the second terminal into a second conversion voltage between the third terminal and the fourth terminal. The second battery rack is connected between the first set of terminals and the third terminal of the first power conversion circuit. The battery controller is configured to control the first power conversion circuit to adjust the level of the second conversion voltage.

[0010] In some embodiments, the second battery rack may be connected between the first terminal and the second terminal of the first power conversion circuit. The first terminal of the first power conversion circuit may be connected to the first group of terminals. The second terminal and the third terminal of the first power conversion circuit may be connected to each other.

[0011] In other embodiments, the first power conversion circuit may further include a first switch between the first terminal and a first intermediate node of the first power conversion circuit, a second switch between the first intermediate node and the fourth terminal, and an inductor between the first intermediate node and a second intermediate node of the first power conversion circuit, the second intermediate node being commonly connected to the second terminal and the third terminal of the first power conversion circuit.

[0012] In other embodiments, the first power conversion circuit may further include an additive polarity transformer, the additive polarity transformer including a primary coil connected between the first terminal and the second terminal and a secondary coil connected between the third terminal and the fourth terminal, a first switch connected in series to the primary coil between the first terminal and the second terminal, and a second switch connected in series to the secondary coil between the third terminal and the fourth terminal.

[0013] In other embodiments, the first battery rack may be connected between a first terminal and a second terminal of the first power conversion circuit. The first terminal of the first power conversion circuit may be connected to the first group of terminals. The second terminal and the fourth terminal of the first power conversion circuit may be commonly connected to the second group of terminals.

[0014] In other embodiments, the first power conversion circuit may further include a first switch between the first terminal and a first intermediate node of the first power conversion circuit, an inductor between the first intermediate node and the third terminal, and a second switch between the first intermediate node and a second intermediate node commonly connected to the second terminal and the fourth terminal.

[0015] In other embodiments, the battery pack may further include a battery module and a second power conversion circuit. The battery module may be connected between the first terminal and the second terminal of the first power conversion circuit. The second power conversion circuit may include a fifth terminal connected to the first set of terminals, a sixth terminal connected to the second set of terminals, a seventh terminal, and an eighth terminal. The second power conversion circuit may be configured to bidirectionally convert a first battery voltage of the first battery rack connected between the fifth and sixth terminals to a third battery voltage of the battery module connected between the seventh and eighth terminals.

[0016] In other embodiments, the first power conversion circuit may further include a first switch between the first terminal and a first intermediate node, a second switch between the first intermediate node and the fourth terminal, and an inductor between the first intermediate node and a second intermediate node commonly connected to the second terminal and the third terminal.

[0017] In other embodiments, the second power conversion circuit may further include an additive polarity transformer, the additive polarity transformer including a primary coil connected between the fifth terminal and the sixth terminal and a secondary coil connected between the seventh terminal and the eighth terminal, a third switch connected in series to the primary coil between the fifth terminal and the sixth terminal, and a fourth switch connected in series to the secondary coil between the seventh terminal and the eighth terminal.

[0018] In other embodiments, the first power conversion circuit may further include an inductor between the first terminal and a first intermediate node, a first switch between the first intermediate node and the third terminal, and a second switch between the first intermediate node and a second intermediate node commonly connected to the second terminal and the fourth terminal.

[0019] In other embodiments, the second power conversion circuit may further include an additive polarity transformer, a third switch, and a diode, the additive polarity transformer including a primary coil connected between the fifth terminal and the sixth terminal and a secondary coil connected between the seventh terminal and the eighth terminal, the third switch being connected in series to the primary coil between the fifth terminal and the sixth terminal, and the diode being connected in series to the secondary coil between the seventh terminal and the eighth terminal with a reverse bias.

[0020] In other embodiments, the battery controller may be further configured to detect a third state of charge of the battery module and control the second power conversion circuit based on the third state of charge.

[0021] In other embodiments, the battery controller may be further configured to detect a first state of charge of the first battery rack and a second state of charge of the second battery rack, and adjust a level of the second conversion voltage based on a difference between the first state of charge and the second state of charge.

[0022] In other embodiments, the battery controller may be further configured to: if the second state of charge is less than the first state of charge in the charging mode, reduce the level of the second conversion voltage to increase the charging current of the second battery rack. The battery controller may be further configured to: if the second state of charge is less than the first state of charge in the discharging mode, reduce the level of the second conversion voltage to reduce the discharging current of the second battery rack.

[0023] In other embodiments, the battery controller may also be configured to detect a first battery current capacity of the first battery rack and a second battery current capacity of the second battery rack, detect a first battery current flowing through the first battery rack and a second battery current flowing through the second battery rack, and adjust a level of the second conversion voltage so that a ratio of the second battery current to the first battery current may be equal to a ratio of the second battery current capacity to the first battery current capacity.

[0024] According to one or more embodiments, a battery pack includes a first battery rack, a first power conversion circuit, a second battery rack, and a battery controller. The first battery rack is connected between a first group of terminals and a second group of terminals and has a first battery voltage. The first power conversion circuit includes a first terminal, a second terminal, a third terminal, a fourth terminal, and a capacitor arranged between the third terminal and the fourth terminal. The first power conversion circuit is configured to bidirectionally convert a first conversion voltage between the first terminal and the second terminal into a second conversion voltage between both ends of the capacitor. The second battery rack is connected between the first group of terminals and the third terminal of the first power conversion circuit and has a second battery voltage. The battery controller is configured to control the first power conversion circuit to adjust the level of the second conversion voltage of the first power conversion circuit. The second battery rack and the capacitor of the first power conversion circuit are connected in series with each other between the first group of terminals and the second group of terminals.

[0025] In some embodiments, the second battery rack may be connected between the first terminal and the second terminal of the first power conversion circuit.

[0026] In other embodiments, the first battery rack may be connected between the first terminal and the second terminal of the first power conversion circuit.

[0027] In other embodiments, the battery pack may further include a battery module and a second power conversion circuit. The battery module may be connected between the first terminal and the second terminal of the first power conversion circuit and may have a third battery voltage. The second power conversion circuit may include a fifth terminal connected to the first set of terminals, a sixth terminal connected to the second set of terminals, a seventh terminal connected to the first terminal, and an eighth terminal connected to the second terminal. The second power conversion circuit may be configured to bidirectionally convert the first battery voltage between the fifth terminal and the sixth terminal into a third battery voltage between the seventh terminal and the eighth terminal.

[0028] In other embodiments, the battery controller may also be configured to detect a first battery current flowing through the first battery rack and a second battery current flowing through the second battery rack, and adjust the level of the second conversion voltage based on a ratio of the second battery current to the first battery current and a ratio of the second battery capacity of the second battery rack to the first battery capacity of the first battery rack. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0030] Figure 1 is a block diagram illustrating a battery pack according to an embodiment of the present disclosure;

[0031] Figure 2 It shows Figure 1 A circuit diagram of an example of a battery pack shown in ;

[0032] Figure 3 It shows Figure 1 A circuit diagram of another example of a battery pack shown in ;

[0033] Figure 4 is a block diagram illustrating a battery pack according to other embodiments of the present disclosure;

[0034] Figure 5 It shows Figure 4 A circuit diagram of an example of a battery pack shown in ;

[0035] Figure 6 is a block diagram illustrating a battery pack according to other embodiments of the present disclosure;

[0036] Figure 7 It shows Figure 6 A circuit diagram of an example of a battery pack shown in ; and

[0037] Figure 8 It shows Figure 6 A circuit diagram of another example of a battery pack is shown in FIG. DETAILED DESCRIPTION

[0038] Reference will now be made in detail to an embodiment, examples of which are illustrated in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout. In this respect, the present embodiment may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the following description will only describe the embodiments with reference to the accompanying drawings to explain various aspects of this description. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of...", if following a list of elements, modify the entire list of elements without modifying the individual elements in the list.

[0039] Hereinafter, embodiments of the present disclosure will be described. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but are interpreted based on the meaning and concepts corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms for the best interpretation. For example, the embodiments and the accompanying drawings presented herein are merely preferred examples for illustrative purposes only and are not intended to limit the scope of the present disclosure, and it should be understood that other equivalents and modifications may be made thereto without departing from the spirit and scope of the present disclosure.

[0040] The meanings of “comprise,” “include,” “comprising,” and / or “including” specify a shape, number, step, operation, component, element, and / or a combination thereof, but do not exclude other shapes, numbers, steps, operations, components, elements, and / or a combination thereof. In the description of the embodiments, phrases such as “can,” “may,” or “will be” may be used to indicate one or more embodiments.

[0041] To help understand the present disclosure, the accompanying drawings may not be drawn to scale and some dimensions of elements may be exaggerated. For example, in different embodiments, the same reference numerals may be assigned to the same elements.

[0042] A statement that two objects are “the same” may mean that the two objects are “substantially the same.” The expression “substantially the same” may include variations that are considered minor in the relevant industry, such as a deviation of 5% or less. A statement that a parameter is uniform over a certain range may mean that the parameter is uniform from an average perspective.

[0043] It will be understood that although terms such as "first" and "second" are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from other elements. Unless otherwise specified, a first element may be referred to as a second element, and vice versa.

[0044] Throughout the specification, unless otherwise specified, the number of each element may be one or more.

[0045] If an element is referred to as being “on (or below)” or “on” another element, it can be directly on the upper surface (lower surface) of the other element while being in contact with the other element, or can be above (under) the other element with an intervening element therebetween.

[0046] For example, "connected," "coupled," or "accessed" between elements may refer to direct connection, coupling, or access, or may refer to indirect connection, coupling, or access with other elements intervening or involving other elements. For example, if a part or element is referred to as being electrically coupled to another part or element, the part or element may be directly connected to the other part or element, or may be connected to the other part or element with intervening parts or elements intervening.

[0047] In this specification, unless otherwise specified, the expression "A and / or B" indicates A, B, or A and B. For example, the expression "and / or" may include any and all combinations of one or more of the associated items. Unless otherwise specified, a range of "C to D" indicates a range greater than or equal to C and less than or equal to D.

[0048] As described herein, unlike primary batteries, secondary batteries are rechargeable. A battery cell is the basic unit of a secondary battery, and each battery cell includes: an electrode assembly formed by a positive electrode, a separator, and a negative electrode; electrode terminals, each connected to a corresponding one of the positive electrode and the negative electrode; and a housing that houses the electrode assembly and the electrolyte. Each battery module is an assembly in which a predetermined number of battery cells are combined with each other and placed in a frame to increase the battery output power and protect the battery cells from external shock, heat, and vibration. Each battery rack is used to connect multiple battery modules to each other, and each battery rack is ultimately provided by adding a battery management system to the multiple battery modules for thermal management and electrical control. Such a battery management system may include a microcontroller unit (MCU), an analog front end (AFE), protection devices, and sensors. Each battery pack may include a battery rack connected in parallel to each other and a controller configured to communicate with the battery management system of the battery rack for managing and controlling the overall operation of the battery pack.

[0049] After a battery pack has been used for an extended period of time, an old battery rack of the battery pack may be replaced with a new one, a new battery rack may be added to the battery pack, some battery modules may be replaced with new ones, or new battery modules may be added to the battery pack. In this case, the new battery rack and the existing old battery rack may be connected in parallel, which may lead to impedance imbalance issues. For example, if the old battery rack is completely discharged, even though the new battery rack retains energy, the energy stored in the battery modules of the new battery rack may not be usable.

[0050] To address this issue, the old battery racks are connected in parallel to a power conversion circuit and used together with the new battery racks. However, this requires a power conversion circuit with a capacity large enough to handle the battery racks, and this can lead to various problems, such as increased financial burden, power consumption due to power conversion efficiency, heat generation, and space constraints.

[0051] Figure 1 is a block diagram illustrating a battery pack 100 according to an embodiment of the present disclosure.

[0052] refer to Figure 1 The battery pack 100 may include a first group of terminals 101, a second group of terminals 102, a first battery rack 110, a second battery rack 120, a power conversion circuit 130, and a battery controller 140. The first battery rack 110 may be connected between the first group of terminals 101 and the second group of terminals 102. The power conversion circuit 130 may have a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The fourth terminal P4 of the power conversion circuit 130 may be connected to the second group of terminals 102. The power conversion circuit 130 may bidirectionally convert a first conversion voltage V2 between the first terminal P1 and the second terminal P2 into a second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The second battery rack 120 may be connected between the first group of terminals 101 and the third terminal P3 of the power conversion circuit 130. The battery controller 140 may control the power conversion circuit 130 to adjust the level of the second conversion voltage V3.

[0053] The first and second group terminals 101, 102 may be connected to a charging device configured to charge the battery pack 100 or to an electrical load to receive power from the battery pack 100. The voltage between the first and second group terminals 101, 102 may be referred to as a pack voltage, and it may be assumed that the first group terminals 101 have a higher potential than the second group terminals 102.

[0054] The first battery rack 110 may include a plurality of first battery modules connected in series. For example, the first battery rack 110 may include twelve or sixteen first battery modules connected in series. For example, each of the first battery modules may have a battery capacity of 7.6 kWh and a module voltage of approximately 68.2 V to approximately 91.3 V, depending on its state of charge. The voltage between the positive and negative terminals of the first battery rack 110 may be referred to as a first battery voltage V1 or a first rack voltage V1.

[0055] Each of the first battery modules may include a plurality of first battery cells. For example, each of the first battery modules may include twenty-two first battery cells, each of which has a cell capacity of 94 Ah and is connected in series with one another. The first battery cells may be portions for storing power and may be rechargeable secondary battery cells. For example, the first battery cells may each include at least one member selected from the group consisting of a lithium-ion battery cell, a lithium polymer battery cell, a nickel-cadmium battery cell, a nickel-metal hydride (Ni-MH) battery cell, a nickel-zinc (Ni-Zn) battery cell, and a lead-acid battery cell.

[0056] Each of the first battery modules may include a first module management unit configured to manage the first battery cells. The first battery rack 110 may further include a first rack management unit communicatively connected to the first module management units of the first battery modules.

[0057] The number of first battery modules in the first battery rack 110 and the connection relationship between the first battery modules do not limit the scope of the present disclosure. The number of first battery cells in each first battery module and the connection relationship between the first battery cells do not limit the scope of the present disclosure.

[0058] The second battery rack 120 may include a plurality of second battery modules connected in series. For example, the second battery rack 120 may include four, six, or eight second battery modules connected in series. For example, each of the second battery modules may have a battery capacity of 24.3 kWh and a module voltage of approximately 68.2 V to approximately 91.3 V, depending on its state of charge. The voltage between the positive and negative terminals of the second battery rack 120 may be referred to as a second battery voltage V2 or a second rack voltage V2.

[0059] Each of the second battery modules may include a plurality of second battery cells. For example, each of the second battery modules may include forty-four battery cells, each battery cell having a battery capacity of 150 Ah and connected in series and in parallel with each other. For example, two battery string sets each including twenty-two second battery cells connected in series with each other may be connected in parallel to form a second battery module. The second battery cell may be a portion for storing electricity and may be a rechargeable secondary battery cell. For example, the second battery cell may be a lithium-ion battery cell, a lithium polymer battery cell, a nickel-cadmium battery cell, a Ni-MH battery cell, a Ni-Zn battery cell, or a lead-acid battery cell.

[0060] Each of the second battery modules may include a second module management unit configured to manage the second battery cells. The second battery rack 120 may further include a second rack management unit communicatively connected to the second module management unit.

[0061] The number of second battery modules of the second battery rack 120 , the connection relationship between the second battery modules, the number of second battery cells in each of the second battery modules, and the connection relationship between the second battery cells do not limit the scope of the present disclosure.

[0062] The first battery rack 110 and the second battery rack 120 may have different configurations. The first battery rack 110 and the second battery rack 120 may have different numbers of battery modules and different connection relationships between the battery modules. For example, the first battery rack 110 may include twelve battery modules, and the second battery rack 120 may include four battery modules. The first battery rack 110 and the second battery rack 120 may include battery modules with different numbers of battery cells and different connection relationships between the battery cells. For example, each battery module of the first battery rack 110 may include a battery cell with a cell capacity of 94 Ah, and each battery module of the second battery rack 120 may include a battery cell with a cell capacity of 150 Ah. Even if the first battery rack 110 and the second battery rack 120 include the same battery cells, the battery cells may have different states of health. For example, the first battery rack 110 may include new first battery cells, and the second battery rack 120 may include aged second battery cells.

[0063] The first battery rack 110 may be connected between the first set of terminals 101 and the second set of terminals 102. The positive terminal of the first battery rack 110 may be substantially directly connected to the first set of terminals 101, and the negative terminal of the first battery rack 110 may be substantially directly connected to the second set of terminals 102. A contactor or circuit breaker may be provided between the positive terminal of the first battery rack 110 and the first set of terminals 101, and / or a contactor or circuit breaker may be provided between the negative terminal of the first battery rack 110 and the second set of terminals 102.

[0064] The battery pack 100 may further include a first current sensor 111 configured to detect a first battery current i1 flowing through the first battery rack 110. The battery pack 100 may further include a second current sensor 121 configured to detect a second battery current i2 flowing through the second battery rack 120. The battery controller 140 may detect the first battery current i1 flowing through the first battery rack 110 by using the first current sensor 111, and may detect the second battery current i2 flowing through the second battery rack 120 by using the second current sensor 121.

[0065] In another example, the first current sensor 111 may be included in the first battery rack 110. The first rack management unit of the first battery rack 110 may detect the first battery current i1 flowing through the first battery rack 110 by using the first current sensor 111 and may provide the magnitude of the first battery current i1 to the battery controller 140.

[0066] The second current sensor 121 may be included in the second battery rack 120. The second rack management unit of the second battery rack 120 may detect the second battery current i2 of the second battery rack 120 and may provide the magnitude of the second battery current i2 to the battery controller 140. The first rack management unit of the first battery rack 110, the second rack management unit of the second battery rack 120, and the battery controller 140 may exchange data through communication.

[0067] In another example, the total pack current flowing in the battery pack 100 can be detected by the first group of terminals 101 and the second group of terminals 102. A main current sensor can be provided in a high current path between the first group of terminals 101 and the second group of terminals 102. The battery controller 140 can also use the main current sensor to detect the pack current. In another example, the first group of terminals 101 and the second group of terminals 102 can be connected to an integrated controller such as a power conversion device, and the integrated controller can detect the pack current of the battery pack 100 and provide the magnitude of the pack current to the battery controller 140. The battery controller 140 can calculate or predict the magnitude of the first battery current i1 based on the result of subtracting the magnitude of the second battery current i2 from the magnitude of the pack current.

[0068] The power conversion circuit 130 may be a bidirectional DC / DC converter including first to fourth terminals P1, P2, P3, and P4. The power conversion circuit 130 may convert a first conversion voltage V2 (i.e., the second battery voltage V2) between the first terminal P1 and the second terminal P2 into a second conversion voltage V3, and may output the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The power conversion circuit 130 may convert the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V2, and may output the first conversion voltage V2 between the first terminal P1 and the second terminal P2.

[0069] The first terminal P1 and the second terminal P2 may be connected to the second battery rack 120 and may receive a second battery voltage V2 of the second battery rack 120. The first converted voltage V2 between the first terminal P1 and the second terminal P2 may be substantially the same as the second battery voltage V2 of the second battery rack 120. The first terminal P1 may be connected to the first group of terminals 101, and the fourth terminal P4 may be connected to the second group of terminals 102. The second terminal P2 and the third terminal P3 may be connected to each other.

[0070] For example, Figure 1As shown, the third terminal P3 and the fourth terminal P4 of the second battery rack 120 and the power conversion circuit 130 can be connected in series with each other between the first group of terminals 101 and the second group of terminals 102, and the first battery voltage V1 of the first battery rack 110 can be substantially the same as the sum of the second battery voltage V2 and the second conversion voltage V3 of the second battery rack 120.

[0071] The power conversion circuit 130 may be controlled by a battery controller 140. The battery controller 140 may adjust the level of the second conversion voltage V3 based on the second battery current i2. For example, the battery controller 140 may adjust the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 is equal to a set ratio value. For example, the set ratio value may be set based on the ratio of the first battery current capacity of the first battery rack 110 to the second battery current capacity of the second battery rack 120.

[0072] As the first battery rack 110 and the second battery rack 120 age, the battery capacity of the first battery rack 110 and the battery capacity of the second battery rack 120 may decrease, and therefore, the battery controller 140 may periodically monitor the first battery current capacity of the first battery rack 110 and the second battery current capacity of the second battery rack 120. The battery controller 140 may update or reset the ratio setting value based on the ratio of the first battery current capacity of the first battery rack 110 and the second battery current capacity of the second battery rack 120. For example, the term "battery current capacity" may refer to the total amount of current that can be discharged when the state of charge decreases from 100% to 0%, and may be expressed in Ah. In this specification, the cell capacity is expressed in Ah, and the battery capacity is expressed in Wh.

[0073] The battery controller 140 can control the power conversion circuit 130 so that the ratio of the first battery current i1 and the second battery current i2 can be equal to the ratio of the first battery current capacity and the second battery current capacity, and thus, the first state of charge SOC1 of the first battery rack 110 and the second state of charge SOC2 of the second battery rack 120 can increase or decrease in response to each other.

[0074] For example, if the first battery rack 110 includes twelve first battery modules, each having a battery capacity of 7.6 kWh, the first battery rack 110 can have a first battery capacity of approximately 91.3 kWh. For example, if the second battery rack 120 includes six second battery modules, each having a battery capacity of 24.3 kWh, the second battery rack 120 can have a second battery capacity of approximately 145.7 kWh. The first battery voltage V1 of the first battery rack 110 including twelve first battery modules can be approximately twice the second battery voltage V2 of the second battery rack 120 including six second battery modules.

[0075] The ratio of the first battery current capacity of the first battery rack 110 to the second battery current capacity of the second battery rack 120 may be approximately 91.3 / 2:145.7. In some embodiments, the battery controller 140 may set the ratio setting value to 1:3.2 and may adjust the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 may be 1:3.2.

[0076] For example, if the ratio of the first battery current i1 to the second battery current i2 is, for example, 1:3.0 when the battery pack 100 is charged, the battery controller 140 may reduce the level of the second conversion voltage V3 to increase the second battery current i2. The battery controller 140 may reduce the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 may increase to a ratio setting value.

[0077] If the ratio of the first battery current i1 to the second battery current i2 is, for example, 1:3.0 when the battery pack 100 is discharged, the battery controller 140 may increase the level of the second conversion voltage V3 to increase the second battery current i2. The battery controller 140 may increase the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 may increase to a ratio setting value.

[0078] In other embodiments, the battery controller 140 may monitor the first state of charge (SOC1) of the first battery rack 110 and the second state of charge (SOC2) of the second battery rack 120. For example, the battery controller 140 may monitor the first state of charge (SOC1) based on the first battery current i1 and the second state of charge (SOC2) based on the second battery current i2 using a coulomb counting method. In another example, the battery controller 140 may estimate the first state of charge (SOC1) based on the open-circuit voltage of the first battery rack 110 and estimate the second state of charge (SOC2) based on the open-circuit voltage of the second battery rack 120. In another example, the battery controller 140 may receive information about the first state of charge (SOC1) from a first rack management unit of the first battery rack 110 and receive information about the second state of charge (SOC2) from a second rack management unit of the second battery rack 120.

[0079] The battery controller 140 may adjust the level of the second conversion voltage V3 based on the first and second states of charge SOC1 and SOC2. For example, the battery controller 140 may adjust the level of the second conversion voltage V3 so that the first and second states of charge SOC1 and SOC2 may be equal to each other.

[0080] For example, if the first state of charge (SOC1) is greater than the second state of charge (SOC2) when the battery pack 100 is charged, the battery controller 140 may increase the second battery current i2 for charging the second battery rack 120, and thus the second state of charge (SOC2) may increase faster than the first state of charge (SOC1). To this end, the battery controller 140 may reduce the level of the second conversion voltage V3.

[0081] For example, if the first state of charge (SOC1) is greater than the second state of charge (SOC2) when the battery pack 100 is discharged, the battery controller 140 may reduce the second battery current i2 flowing out of the second battery rack 120, and thus the second state of charge (SOC2) may decrease more slowly than the first state of charge (SOC1). To this end, the battery controller 140 may reduce the level of the second conversion voltage V3.

[0082] In the related art, a first battery rack is connected to a second battery rack of a different type using a power conversion circuit. This power conversion circuit is configured to convert the second rack voltage of the second battery rack to the first rack voltage of the first battery rack. This power conversion circuit must convert all power output from the second battery rack and therefore has a power conversion capacity sufficient to cover the entire second battery rack. This not only increases the size and manufacturing cost of the power conversion circuit, but also requires a separate heat sink to handle the heat generated during the power conversion process.

[0083] In the present disclosure, the power conversion circuit 130 and the second battery rack 120 are connected in series with each other, and therefore, the power conversion circuit 130 can convert only the power required to maintain the second conversion voltage V3. For example, the power conversion circuit 130 can have a smaller power conversion capacity than the power conversion circuit of the related art. For example, the size and manufacturing cost of the power conversion circuit 130 can be reduced, and a separate heat dissipation unit can be omitted because heat generation during the power conversion process is reduced. For example, the power conversion circuit 130 can not emit a large amount of heat, and therefore, the total area occupied by the battery pack 100 can be reduced by placing the power conversion circuit 130 near the first battery rack 110 and the second battery rack 120.

[0084] Figure 2 It shows Figure 1 An example circuit diagram of a battery pack 100 is shown in FIG.

[0085] refer to Figure 2 , the battery pack 100a may include a first battery rack 110 connected between a first terminal group 101 and a second terminal group 102 and having a first battery voltage V1, a second battery rack 120 having a second battery voltage V2, and a power conversion circuit 130a. Figure 21. However, the battery pack 100a may further include a battery controller 140 configured to control the power conversion circuit 130a (see FIG. Figure 1 The battery pack 100a may further include a first current sensor 211 configured to detect a first battery current i1 of the first battery rack 110 (see Figure 4 ) and / or a second current sensor 221 configured to detect a second battery current i2 of the second battery rack 120 (see Figure 4 ).

[0086] The power conversion circuit 130a may be a bidirectional DC / DC converter having a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The first terminal P1 may be commonly connected to the first terminal group 101 and the positive terminal of the second battery rack 120, the second terminal P2 and the third terminal P3 may be commonly connected to the negative terminal of the second battery rack 120, and the fourth terminal P4 may be connected to the second terminal group 102.

[0087] The power conversion circuit 130a may include a first switch Q1 between a first terminal P1 and a first intermediate node N1, a second switch Q2 between the first intermediate node N1 and a fourth terminal P4, and an inductor L between the first intermediate node N1 and a second intermediate node N2. The second intermediate node N2 may be commonly connected to the second terminal P2 and the third terminal P3.

[0088] The first switch Q1 may include a first diode D1, and the second switch Q2 may include a second diode D2. For example, the first switch Q1 and the second switch Q2 may each be an insulated gate bipolar transistor (IGBT) and may include a first diode D1 and a second diode D2 of a body diode type, respectively. In another example, the first switch Q1 and the second switch Q2 may each be a bipolar junction transistor (BJT), a field effect transistor (FET), or a metal oxide semiconductor FET (MOSFET).

[0089] The power conversion circuit 130a may further include a first capacitor C1 between the first terminal P1 and the second terminal P2. The power conversion circuit 130a may further include a second capacitor C2 between the third terminal P3 and the fourth terminal P4. The first capacitor C1 may be omitted.

[0090] The power conversion circuit 130a can convert the first conversion voltage V2 between the first terminal P1 and the second terminal P2 into a second conversion voltage V3, and output the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The power conversion circuit 130a can convert the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V1, and output the first conversion voltage V1 between the first terminal P1 and the second terminal P2.

[0091] For example, if the first switch Q1 is turned on, current can flow from the first terminal P1 to the second terminal P2 through the first switch Q1 and the inductor L, and energy can be accumulated in the inductor L. If the first switch Q1 is turned off, the energy accumulated in the inductor L can be moved to the second capacitor C2 through the second diode D2. Therefore, the first conversion voltage V2 between the first terminal P1 and the second terminal P2 can be converted into a second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The level of the second conversion voltage V3 can be adjusted according to the duty cycle of the first switch Q1. The battery controller 140 can adjust the level of the second conversion voltage V3 by controlling the duty cycle of the first switch Q1.

[0092] If the second switch Q2 is turned on, current can flow from the third terminal P3 to the fourth terminal P4 through the inductor L and the second switch Q2, and the energy stored in the second capacitor C2 can be accumulated in the inductor L. If the second switch Q2 is turned off, the energy accumulated in the inductor L can be moved to the first capacitor C1 and the second battery rack 120 through the first diode D1. Therefore, the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 can be converted into the first conversion voltage V2 between the first terminal P1 and the second terminal P2. The level of the first conversion voltage V2 and the level of the second conversion voltage V3 can be adjusted according to the duty cycle of the second switch Q2. The battery controller 140 can adjust the level of the second conversion voltage V3 by controlling the duty cycle of the second switch Q2.

[0093] For example, the first battery rack 110 may include twelve first battery modules connected in series, and each of the first battery modules may include twenty-two first battery cells connected in series. Each of the first battery cells may have a cell capacity of 94 Ah. The battery capacity of the first battery rack 110 may be 91.3 kWh. Depending on the state of charge of the first battery rack 110, the first battery voltage V1 of the first battery rack 110 may range from approximately 818.4 V to approximately 1095.6 V, for example.

[0094] The second battery rack 120 may include four second battery modules connected in series, and each of the second battery modules may include 44 second battery cells connected in series and in parallel. Each of the second battery cells may have a cell capacity of 150 Ah. The battery capacity of the second battery rack 120 may be 97.7 kWh. Depending on the state of charge of the second battery rack 120, the second battery voltage V2 of the second battery rack 120 may be, for example, approximately 272.8 V to approximately 365.2 V.

[0095] Depending on the first battery voltage V1 and the second battery voltage V2, the second conversion voltage V3 of the power conversion circuit 130a may be approximately 545.6V to approximately 730.4V. The power conversion circuit 130a may output the second conversion voltage V3 by increasing the first conversion voltage V2 by approximately 2 times. The step-up ratio of the power conversion circuit 130a may be approximately 2. The step-down ratio of the power conversion circuit 130a may be adjusted by the battery controller 140 based on the first battery current i1 and the second battery current i2. For example, the power conversion circuit 130a may have a power conversion capacity of approximately 50kW.

[0096] Figure 3 It shows Figure 1 A circuit diagram of another example of a battery pack 100 is shown in FIG.

[0097] refer to Figure 3 , the battery pack 100b may include a first battery rack 110 connected between a first terminal group 101 and a second terminal group 102 and having a first battery voltage V1, a second battery rack 120 having a second battery voltage V2, and a power conversion circuit 130b. Figure 3 1. The battery pack 100b may further include a battery controller 140 (see FIG. 1 ) configured to control the power conversion circuit 130b. Figure 1 ), the first current sensor 111 (reference Figure 1 ) and the second current sensor 121 (reference Figure 1 ) is selected from the group consisting of at least one component.

[0098] The power conversion circuit 130b may be a bidirectional DC / DC converter having a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The power conversion circuit 130b may be a flyback converter. The first terminal P1 may be commonly connected to the first set of terminals 101 and the positive terminal of the second battery rack 120, the second terminal P2 may be commonly connected to the negative terminal of the second battery rack 120 and the third terminal P3, and the fourth terminal P4 may be connected to the second set of terminals 102.

[0099] The power conversion circuit 130b may include an additive polarity transformer TR, and the additive polarity transformer TR may include a primary coil L1 connected between a first terminal P1 and a second terminal P2, and a secondary coil L2 connected between a third terminal P3 and a fourth terminal P4. The ratio of the number of turns of the primary coil L1 to the number of turns of the secondary coil L2 may be set according to the target voltage conversion ratio of the power conversion circuit 130b.

[0100] The power conversion circuit 130b may include a first switch Q1 connected in series to the primary coil L1 between a first terminal P1 and a second terminal P2, and a second switch Q2 connected in series to the secondary coil L2 between a third terminal P3 and a fourth terminal P4. The first switch Q1 may include a first diode D1, and the second switch Q2 may include a second diode D2. For example, the first switch Q1 and the second switch Q2 may each be an IGBT and may include a first diode D1 and a second diode D2 of a body diode type, respectively. In another example, the first switch Q1 and the second switch Q2 may each be a BJT, a FET, or a MOSFET.

[0101] The power conversion circuit 130b may further include a second capacitor C2 between the third terminal P3 and the fourth terminal P4. The power conversion circuit 130b may further include a first capacitor C1 between the first terminal P1 and the second terminal P2. The first capacitor C1 may be omitted.

[0102] The power conversion circuit 130b can convert the first conversion voltage V2 between the first terminal P1 and the second terminal P2 into a second conversion voltage V3, and output the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. For example, the battery controller 140 can adjust the level of the second conversion voltage V3 by controlling the duty cycle of the first switch Q1.

[0103] The power conversion circuit 130b may convert the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V2, and output the first conversion voltage V2 between the first terminal P1 and the second terminal P2. For example, the battery controller 140 may adjust the levels of the first conversion voltage V2 and the second conversion voltage V3 by controlling the duty cycle of the second switch Q2.

[0104] For example, the first battery rack 110 may include twelve first battery modules connected in series, and each of the first battery modules may include twenty-two first battery cells connected in series. Each of the first battery cells may have a cell capacity of 94 Ah. The battery capacity of the first battery rack 110 may be 91.3 kWh. Depending on the state of charge of the first battery rack 110, the first battery voltage V1 of the first battery rack 110 may range from approximately 818.4 V to approximately 1095.6 V, for example.

[0105] The second battery rack 120 may include six second battery modules connected in series, and each of the second battery modules may include forty-four second battery cells connected in series and in parallel. Each of the second battery cells may have a cell capacity of 150 Ah. The battery capacity of the second battery rack 120 may be 145.7 kWh. Depending on the state of charge of the second battery rack 120, the second battery voltage V2 of the second battery rack 120 may be, for example, approximately 409.2 V to approximately 547.8 V.

[0106] Depending on the first battery voltage V1 and the second battery voltage V2, the second converted voltage V3 of the power conversion circuit 130b may be approximately 409.2V to approximately 547.8V. The power conversion circuit 130b may output the second converted voltage V3 such that the magnitude of the first converted voltage V2 and the magnitude of the second converted voltage V3 are approximately 1:1. As described above, the voltage conversion ratio of the power conversion circuit 130b may be controlled by the battery controller 140 based on the first battery current i1 of the first battery rack 110 and the second battery current i2 of the second battery rack 120. For example, the power conversion circuit 130b may have a power conversion capacity of approximately 69kW.

[0107] Figure 4 is a block diagram illustrating a battery pack 200 according to other embodiments of the present disclosure.

[0108] refer to Figure 4 The battery pack 200 may include a first group of terminals 201 , a second group of terminals 202 , a first battery rack 210 having a first battery voltage V1 , a second battery rack 220 having a second battery voltage V2 , a power conversion circuit 230 , and a battery controller 240 .

[0109] The power conversion circuit 230 may include a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The first terminal P1 may be connected to the first terminal group 201, and the second terminal P2 and the fourth terminal P4 may be connected to the second terminal group 202. The power conversion circuit 230 may bidirectionally convert a first conversion voltage V1 between the first terminal P1 and the second terminal P2 into a second conversion voltage V3 between the third terminal P3 and the fourth terminal P4.

[0110] The first battery rack 210 may be connected between the first terminal group 201 and the second terminal group 202. The first battery rack 210 may be connected between the first terminal P1 and the second terminal P2 of the power conversion circuit 230. The second battery pack 220 may be connected between the first terminal group 201 and the third terminal P3 of the power conversion circuit 230. The battery controller 240 may control the power conversion circuit 230 to adjust the level of the second conversion voltage V3.

[0111] The first battery rack 210 may include a plurality of first battery modules connected in series. Each of the first battery modules in the first battery rack 210 may include a plurality of first battery cells. The second battery rack 220 may include a plurality of second battery modules connected in series. Each of the second battery modules in the second battery rack 220 may include a plurality of second battery cells. The first battery rack 210 and the second battery rack 220 may have different configurations.

[0112] The positive terminal and the negative terminal of the first battery rack 210 can be directly connected to the first terminal group 201 and the second terminal group 202, respectively. The first battery rack 210 can be connected between the first terminal group 201 and the second terminal group 202 through a contactor or a circuit breaker.

[0113] The battery pack 200 may further include a first current sensor 211 and a second current sensor 221. The battery controller 240 may detect a first battery current i1 flowing through the first battery rack 210 using the first current sensor 211 and a second battery current i2 flowing through the second battery rack 220 using the second current sensor 221.

[0114] The power conversion circuit 230 may be a bidirectional DC / DC converter including a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The power conversion circuit 230 may convert a first conversion voltage V1 between the first terminal P1 and the second terminal P2 into a second conversion voltage V3, and output the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The power conversion circuit 230 may convert the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V1, and output the first conversion voltage V1 between the first terminal P1 and the second terminal P2.

[0115] The first terminal P1 and the second terminal P2 may be connected to the first battery rack 210 and may receive the first battery voltage V1 of the first battery rack 210. The first converted voltage V1 between the first terminal P1 and the second terminal P2 may be substantially the same as the first battery voltage V1 of the first battery rack 210. The first terminal P1 may be connected to the first group of terminals 201, and the second terminal P2 and the fourth terminal P4 may be connected to the second group of terminals 202. The third terminal P3 may be connected to the negative terminal of the second battery rack 220. For example, Figure 4 As shown, the third terminal P3 and the fourth terminal P4 of the second battery rack 220 and the power conversion circuit 230 can be connected in series with each other between the first group of terminals 201 and the second group of terminals 202, and the first battery voltage V1 of the first battery rack 210 can be substantially equal to the sum of the second battery voltage V2 and the second conversion voltage V3 of the second battery rack 220.

[0116] The power conversion circuit 230 may be controlled by a battery controller 240. The battery controller 240 may adjust the level of the second conversion voltage V3 based on the second battery current i2. For example, the battery controller 240 may adjust the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 is equal to a preset ratio setting value. For example, the ratio setting value may be determined based on the ratio of the first battery current capacity of the first battery rack 210 to the second battery current capacity of the second battery rack 220.

[0117] The battery controller 240 can control the power conversion circuit 230 so that the ratio of the first battery current i1 and the second battery current i2 can be equal to the ratio of the first battery current capacity of the first battery rack 210 and the second battery current capacity of the second battery rack 220, and therefore, the first state of charge SOC1 of the first battery rack 210 and the second state of charge SOC2 of the second battery rack 220 can increase or decrease in response to each other.

[0118] For example, if the ratio of the first battery current capacity of the first battery rack 210 and the second battery current capacity of the second battery rack 220 is 1:3.2, the battery controller 240 can set the ratio setting value to 1:3.2 and can adjust the level of the second conversion voltage V3 so that the ratio of the first battery current i1 and the second battery current i2 can be 1:3.2.

[0119] For example, if the ratio of the first battery current i1 to the second battery current i2 is, for example, 1:3.4 when the battery pack 200 is charged, the battery controller 240 may increase the level of the second conversion voltage V3 to reduce the second battery current i2. The battery controller 240 may increase the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 may be reduced to a ratio setting value.

[0120] If the ratio of the first battery current i1 to the second battery current i2 is, for example, 1:3.4 when the battery pack 200 is discharged, the battery controller 240 may reduce the level of the second conversion voltage V3 to reduce the second battery current i2. The battery controller 240 may reduce the level of the second conversion voltage V3 so that the ratio of the first battery current i1 to the second battery current i2 can be reduced to a ratio setting value.

[0121] In other embodiments, the battery controller 240 may monitor the first state of charge SOC1 of the first battery rack 210 and the second state of charge SOC2 of the second battery rack 220. The battery controller 240 may adjust the level of the second conversion voltage V3 based on the first state of charge SOC1 and the second state of charge SOC2.

[0122] For example, the battery controller 240 may adjust the level of the second conversion voltage V3 so that the first state of charge (SOC1) and the second state of charge (SOC2) are equal to each other. For example, if the first state of charge (SOC1) is less than the second state of charge (SOC2) when the battery pack 200 is being charged, the battery controller 240 may reduce the second battery current i2 of the second battery rack 220 so that the second state of charge (SOC2) increases more slowly than the first state of charge (SOC1). To this end, the battery controller 240 may increase the level of the second conversion voltage V3.

[0123] For example, assuming that the first state of charge SOC1 is less than the second state of charge SOC2 when the battery pack 200 is discharged, the battery controller 240 can increase the second battery current i2 so that the second state of charge SOC2 can decrease faster than the first state of charge SOC1. To this end, the battery controller 240 can increase the level of the second conversion voltage V3.

[0124] In the present disclosure, the power conversion circuit 230 and the second battery rack 220 are connected in series with each other, and therefore, the power conversion circuit 230 can convert only the power required to maintain the second conversion voltage V3. For example, the power conversion circuit 230 can have a smaller power conversion capacity than the power conversion circuit of the related art. For example, the size and manufacturing cost of the power conversion circuit 230 can be reduced, and a separate heat dissipation unit can be omitted because heat generation during the power conversion process is reduced. For example, the power conversion circuit 230 can not emit a large amount of heat, and therefore, the total area occupied by the battery pack 200 can be reduced by placing the power conversion circuit 230 near the first battery rack 210 and the second battery rack 220.

[0125] Figure 5 It shows Figure 4 An example circuit diagram of a battery pack is shown in FIG.

[0126] refer to Figure 5 , the battery pack 200a may include a first battery rack 210 connected between a first terminal group 201 and a second terminal group 202 and having a first battery voltage V1, a second battery rack 220 having a second battery voltage V2, and a power conversion circuit 230a. Figure 5 2. However, the battery pack 200a may further include a battery controller 240 configured to control the power conversion circuit 230a (see FIG. Figure 4 The battery pack 200a may further include a first current sensor 211 configured to detect a first battery current i1 of the first battery rack 210 (see Figure 4 ) and / or a second current sensor 221 configured to detect a second battery current i2 of the second battery rack 220 (see Figure 4 ).

[0127] The power conversion circuit 230a may be a DC / DC converter having a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The power conversion circuit 230a may be a step-down converter. The first terminal P1 may be commonly connected to the first set of terminals 201 and the positive terminal of the first battery rack 210, the second terminal P2 and the fourth terminal P4 may be commonly connected to the second set of terminals 202, and the third terminal P3 may be connected to the negative terminal of the second battery rack 220.

[0128] The power conversion circuit 230a may include a first switch Q1 between a first terminal P1 and a first intermediate node N1, an inductor L between the first intermediate node N1 and a third terminal P3, and a second switch Q2 between the first intermediate node N1 and a second intermediate node N2. The second intermediate node N2 may be commonly connected to the second terminal P2 and the fourth terminal P4.

[0129] The first switch Q1 may include a first diode D1, and the second switch Q2 may include a second diode D2. For example, the first switch Q1 and the second switch Q2 may each be an IGBT and may include a first diode D1 and a second diode D2 of a body diode type, respectively. In another example, the first switch Q1 and the second switch Q2 may each be a BJT, a FET, or a MOSFET.

[0130] The power conversion circuit 230a may further include a second capacitor C2 between the third terminal P3 and the fourth terminal P4. The power conversion circuit 230a may further include a first capacitor C1 between the first terminal P1 and the second terminal P2. In some embodiments, the first capacitor C1 may be omitted.

[0131] The power conversion circuit 230a can convert a first conversion voltage V1 between the first terminal P1 and the second terminal P2 into a second conversion voltage V3, and output the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The power conversion circuit 230a can convert the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V1, and output the first conversion voltage V1 between the first terminal P1 and the second terminal P2.

[0132] For example, if the first switch Q1 is turned on and the second switch Q2 is turned off, current can flow from the first terminal P1 to the third terminal P3 through the first switch Q1 and the inductor L, and energy stored in the first capacitor C1 can be accumulated in the inductor L. If the first switch Q1 is turned off and the second switch Q2 is turned on, the energy accumulated in the inductor L can be moved to the second capacitor C2. Therefore, the first conversion voltage V1 between the first terminal P1 and the second terminal P2 can be converted to a second conversion voltage V3 between the third terminal P3 and the fourth terminal P4. The level of the second conversion voltage V3 can be adjusted according to the duty cycle of the first switch Q1 and the duty cycle of the second switch Q2. The battery controller 240 can adjust the level of the second conversion voltage V3 by controlling the duty cycle of the first switch Q1 and the duty cycle of the second switch Q2.

[0133] If the second switch Q2 is turned on and the first switch Q1 is turned off, the second capacitor C2, the inductor L, and the second switch Q2 can form a closed circuit, and current can flow from the first intermediate node N1 to the second intermediate node N2 through the inductor L, so that the energy stored in the second capacitor C2 can be accumulated in the inductor L. If the second switch Q2 is turned off, the energy accumulated in the inductor L can be moved to the first capacitor C1 through the first diode D1. Therefore, the second conversion voltage V3 between the third terminal P3 and the fourth terminal P4 can be converted into the first conversion voltage V1 between the first terminal P1 and the second terminal P2. The first conversion voltage V1 is the same as the first battery voltage V1 of the first battery rack 210, and therefore, the level of the second conversion voltage V3 can be adjusted according to the duty cycle of the second switch Q2. The battery controller 240 can adjust the level of the second conversion voltage V3 by controlling the duty cycle of the second switch Q2.

[0134] For example, the first battery rack 210 may include twelve first battery modules connected in series, and each of the first battery modules may include twenty-two first battery cells connected in series. Each of the first battery cells may have a cell capacity of 94 Ah. The battery capacity of the first battery rack 210 may be 91.3 kWh. Depending on the state of charge of the first battery rack 210, the first battery voltage V1 of the first battery rack 210 may range from approximately 818.4 V to approximately 1095.6 V, for example.

[0135] The second battery rack 220 may include four second battery modules connected in series, and each of the second battery modules may include 44 second battery cells connected in series and in parallel. Each of the second battery cells may have a cell capacity of 150 Ah. The battery capacity of the second battery rack 220 may be 97.7 kWh. Depending on the state of charge of the second battery rack 220, the second battery voltage V2 of the second battery rack 220 may be, for example, approximately 272.8 V to approximately 365.2 V.

[0136] Depending on the first battery voltage V1 and the second battery voltage V2, the second conversion voltage V3 of the power conversion circuit 230a may be approximately 545.6V to approximately 730.4V. The power conversion circuit 230a may output the second conversion voltage V3 by reducing the first conversion voltage V1 by approximately 2 / 3. The step-down ratio of the power conversion circuit 230a may be approximately 0.67, and the step-down ratio of the power conversion circuit 230a may be adjusted by the battery controller 240 based on the first battery current i1 and the second battery current i2. For example, the power conversion circuit 230a may have a capacity of approximately 110kW.

[0137] Figure 6 is a block diagram illustrating a battery pack 300 according to other embodiments of the present disclosure.

[0138] refer to Figure 6 The battery pack 300 may include a first set of terminals 301, a second set of terminals 302, a first battery rack 310 having a first battery voltage V1, a second battery rack 320 having a second battery voltage V2, a first power conversion circuit 330, and a battery controller 360. The battery pack 300 may also include a battery module 340 having a third battery voltage V3 and a second power conversion circuit 350.

[0139] The first power conversion circuit 330 may include a first terminal P1, a second terminal P2, a third terminal P3, and a fourth terminal P4. The first terminal P1 may be connected to the positive terminal of the battery module 340, the second terminal P2 may be connected to the negative terminal of the battery module 340, the third terminal P3 may be connected to the second battery rack 320, and the fourth terminal P4 may be connected to the second set of terminals 302. The first power conversion circuit 330 may bidirectionally convert a first converted voltage V3 between the first terminal P1 and the second terminal P2 into a second converted voltage V4 between the third terminal P3 and the fourth terminal P4.

[0140] The second power conversion circuit 350 may include a fifth terminal P5, a sixth terminal P6, a seventh terminal P7, and an eighth terminal P8. The fifth terminal P5 may be connected to the positive terminal of the first battery rack 310 and the first group of terminals 301, the sixth terminal P6 may be connected to the negative terminal of the first battery rack 310 and the second group of terminals 302, the seventh terminal P7 may be connected to the positive terminal of the battery module 340 and the first terminal P1 of the first power conversion circuit 330, and the eighth terminal P8 may be connected to the negative terminal of the battery module 340 and the second terminal P2 of the first power conversion circuit 330.

[0141] The second power conversion circuit 350 can bidirectionally convert the first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6 into a third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8 .

[0142] The first battery rack 310 may be connected between the first terminal group 301 and the second terminal group 302. The first battery rack 310 may be connected between the fifth terminal P5 and the sixth terminal P6 of the second power conversion circuit 350. The second battery rack 320 may be connected between the first terminal group 301 and the third terminal P3 of the first power conversion circuit 330. The battery modules 340 may be commonly connected between the first terminal P1 and the second terminal P2 of the first power conversion circuit 330 and between the seventh terminal P7 and the eighth terminal P8 of the second power conversion circuit 350.

[0143] The battery controller 360 may control the first power conversion circuit 330 to adjust the level of the second conversion voltage V4 and the second power conversion circuit 350 to maintain the state of charge of the battery module 340 within a predetermined range.

[0144] The first battery rack 310 may include a plurality of first battery modules connected in series. Each of the first battery modules in the first battery rack 310 may include a plurality of first battery cells. The second battery rack 320 may include a plurality of second battery modules connected in series. Each of the second battery modules in the second battery rack 320 may include a plurality of second battery cells. The first battery rack 310 and the second battery rack 320 may have different configurations.

[0145] The positive and negative terminals of the first battery rack 310 may be substantially directly connected to the first and second sets of terminals 301 and 302, respectively. The first battery rack 310 may be connected between the first and second sets of terminals 301 and 302 via a contactor or a circuit breaker.

[0146] The battery pack 300 may further include a first current sensor 311 and a second current sensor 321. The battery controller 360 may detect a first battery current i1 flowing through the first battery rack 310 using the first current sensor 311, and may detect a second battery current i2 flowing through the second battery rack 320 using the second current sensor 321. The battery pack 300 may further include a current sensor (not shown) configured to detect a third battery current flowing through the battery module 340.

[0147] The first power conversion circuit 330 may be a bidirectional DC / DC converter. The first power conversion circuit 330 may convert a first conversion voltage V3 between the first terminal P1 and the second terminal P2 into a second conversion voltage V4, and output the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4. The first power conversion circuit 330 may convert the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V3, and output the first conversion voltage V3 between the first terminal P1 and the second terminal P2.

[0148] The first terminal P1 and the second terminal P2 may be connected to the positive terminal and the negative terminal of the battery module 340, respectively, and may receive the third battery voltage V3 of the battery module 340. The first conversion voltage V3 between the first terminal P1 and the second terminal P2 may be substantially the same as the third battery voltage V3 of the battery module 340. The third terminal P3 may be connected to the negative terminal of the second battery rack 320, and the fourth terminal P4 may be connected to the second group of terminals 302. For example, Figure 6 As shown, the third terminal P3 and the fourth terminal P4 of the second battery rack 320 and the first power conversion circuit 330 can be connected in series with each other between the first group of terminals 301 and the second group of terminals 302, and the first battery voltage V1 of the first battery rack 310 can be basically the same as the sum of the second battery voltage V2 and the second conversion voltage V4 of the second battery rack 320.

[0149] The second power conversion circuit 350 may be a bidirectional DC / DC converter. The second power conversion circuit 350 may convert a first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6 into a third battery voltage V3, and output the third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8. The second power conversion circuit 350 may convert the third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8 into a first battery voltage V1, and output the first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6.

[0150] The fifth terminal P5 and the sixth terminal P6 may be connected to the positive terminal and the negative terminal of the first battery rack 310, respectively, and may receive the first battery voltage V1 of the first battery rack 310. The seventh terminal P7 and the eighth terminal P8 may be connected to the positive terminal and the negative terminal of the battery module 340, respectively, and may receive the third battery voltage V3 of the battery module 340.

[0151] The first power conversion circuit 330 and the second power conversion circuit 350 can be controlled by a battery controller 360. The battery controller 360 can adjust the level of the second conversion voltage V4 based on the second battery current i2. For example, the battery controller 360 can adjust the level of the second conversion voltage V4 so that the ratio of the first battery current i1 to the second battery current i2 is equal to a ratio setting value. For example, the ratio setting value can be set based on the ratio of the first battery current capacity of the first battery rack 310 to the second battery current capacity of the second battery rack 320.

[0152] The first power conversion circuit 330 can be controlled to adjust the ratio of the first battery current i1 and the second battery current i2 to be the same as the ratio of the first battery current capacity of the first battery rack 310 and the second battery current capacity of the second battery rack 320, and thus, the first state of charge SOC1 of the first battery rack 310 and the second state of charge SOC2 of the second battery rack 320 can increase or decrease in response to each other.

[0153] In other embodiments, the battery controller 360 may monitor the first state of charge SOC1 of the first battery rack 310 and the second state of charge SOC2 of the second battery rack 320. The battery controller 360 may adjust the level of the second conversion voltage V4 so that the first state of charge SOC1 and the second state of charge SOC2 may be equal to each other.

[0154] The battery controller 360 can detect the third state of charge (SOC3) of the battery module 340. For example, the battery controller 360 can estimate the third state of charge (SOC3) based on the open circuit voltage of the battery module 340. The battery controller 360 can control the second power conversion circuit 350 based on the third state of charge (SOC3). For example, the battery controller 360 can manage the third state of charge (SOC3) of the battery module 340 so that the third state of charge (SOC3) does not exceed a preset range.

[0155] For example, the third state of charge (SOC3) may be maintained within a range of approximately 20% to approximately 80%. If the third state of charge (SOC3) is less than a reference value, the second power conversion circuit 350 may be controlled to charge the battery module 340 using the energy stored in the first battery rack 310. For example, if the third state of charge (SOC3) is greater than a reference value, the second power conversion circuit 350 may be controlled to charge the first battery rack 310 using the energy stored in the battery module 340.

[0156] In some embodiments, the battery controller 360 can control the first power conversion circuit 330 so that the first state of charge (SOC1) of the first battery rack 310 and the second state of charge (SOC2) of the second battery rack 320 are equal. It is understood that the power consumed during the power conversion process of the first power conversion circuit 330 is supplied from the battery module 340. It is understood that the energy used by the battery module 340 to operate the first power conversion circuit 330 is supplied from the first battery rack 310 via the second power conversion circuit 350.

[0157] In the present disclosure, the first power conversion circuit 330 and the second battery rack 320 are connected in series with each other, and therefore, the first power conversion circuit 330 can convert only the power required to maintain the second conversion voltage V4. For example, the first power conversion circuit 330 can have a smaller power conversion capacity than the power conversion circuit of the related art. For example, the size and manufacturing cost of the first power conversion circuit 330 can be reduced, and a separate heat dissipation unit can be omitted because heat generation during the power conversion process is reduced. For example, the first power conversion circuit 330 can not emit a large amount of heat, and therefore, the total area occupied by the battery pack 300 can be reduced by placing the first power conversion circuit 330 near the first battery rack 310 and the second battery rack 320.

[0158] Figure 7 It shows Figure 6 An example circuit diagram of a battery pack 300 is shown in FIG.

[0159] refer to Figure 7 , the battery pack 300a may include a first battery rack 310 connected between a first group of terminals 301 and a second group of terminals 302 and having a first battery voltage V1, a second battery rack 320 having a second battery voltage V2, a first power conversion circuit 330a having first to fourth terminals P1, P2, P3, and P4, a battery module 340 having a third battery voltage V3, and a second power conversion circuit 350a having fifth to eighth terminals P5, P6, P7, and P8. Although Figure 7 3. However, the battery pack 300a may further include a battery controller 360 (see FIG. Figure 6), the battery controller 360 is configured to control the first power conversion circuit 330a and the second power conversion circuit 350a. The battery pack 300a may further include a first current sensor 311 (refer to Figure 6 ) and the second current sensor 321 (reference Figure 6 ).

[0160] The first power conversion circuit 330a may be a DC / DC converter. The first terminal P1 and the second terminal P2 may be connected to the positive terminal and the negative terminal of the battery module 340, respectively. The third terminal P3 may be connected to the negative terminal of the second battery rack 320. The fourth terminal P4 may be connected to the second group of terminals 302.

[0161] The second power conversion circuit 350a may be an isolated DC / DC converter. The fifth terminal P5 and the sixth terminal P6 may be connected to the positive terminal and the negative terminal of the first battery rack 310, respectively. The seventh terminal P7 and the eighth terminal P8 may be connected to the positive terminal and the negative terminal of the battery module 340, respectively.

[0162] The first power conversion circuit 330a may include a first switch Q1 between the first terminal P1 and the first intermediate node N1, a second switch Q2 between the first intermediate node N1 and the fourth terminal P4, and an inductor L between the first intermediate node N1 and the second intermediate node N2. The second intermediate node N2 may be commonly connected to the second terminal P2 and the third terminal P3.

[0163] The first switch Q1 may include a first diode D1, and the second switch Q2 may include a second diode D2. For example, the first switch Q1 and the second switch Q2 may each be an IGBT and may include a first diode D1 and a second diode D2 of a body diode type, respectively. In another example, the first switch Q1 and the second switch Q2 may each be a BJT, a FET, or a MOSFET.

[0164] The first power conversion circuit 330a may further include a second capacitor C2 between the third terminal P3 and the fourth terminal P4. The first power conversion circuit 330a may further include a first capacitor C1 between the first terminal P1 and the second terminal P2. In some embodiments, the first capacitor C1 may be omitted.

[0165] The first power conversion circuit 330a can convert the first conversion voltage V3 between the first terminal P1 and the second terminal P2 into a second conversion voltage V4, and output the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4. The first power conversion circuit 330a can convert the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V3, and output the first conversion voltage V3 between the first terminal P1 and the second terminal P2.

[0166] For example, if the first switch Q1 is turned on, current can flow from the first terminal P1 to the second terminal P2 through the first switch Q1 and the inductor L, and energy stored in the first capacitor C1 and the battery module 340 can be accumulated in the inductor L. If the first switch Q1 is turned off, the energy accumulated in the inductor L can be moved to the second capacitor C2 through the second diode D2. Therefore, the first conversion voltage V3 between the first terminal P1 and the second terminal P2 can be converted into a second conversion voltage V4 between the third terminal P3 and the fourth terminal P4. The level of the second conversion voltage V4 can be adjusted according to the duty cycle of the first switch Q1. The battery controller 360 can adjust the level of the second conversion voltage V4 by controlling the duty cycle of the first switch Q1.

[0167] If the second switch Q2 is turned on, current can flow from the third terminal P3 to the fourth terminal P4 through the inductor L and the second switch Q2, and energy in the second capacitor C2 can be accumulated in the inductor L. If the second switch Q2 is turned off, the energy accumulated in the inductor L can be moved to the first capacitor C1 and the battery module 340 through the first diode D1. Therefore, the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4 can be converted into the first conversion voltage V3 between the first terminal P1 and the second terminal P2. The level of the first conversion voltage V3 and the level of the second conversion voltage V4 can be adjusted according to the duty cycle of the second switch Q2. The battery controller 360 can adjust the level of the second conversion voltage V4 by controlling the duty cycle of the second switch Q2.

[0168] The second power conversion circuit 350a may be a flyback converter. The second power conversion circuit 350a may include an additive polarity transformer TR, which may include a primary coil L1 connected between a fifth terminal P5 and a sixth terminal P6, and a secondary coil L2 connected between a seventh terminal P7 and an eighth terminal P8. The ratio of the number of turns of the primary coil L1 to the number of turns of the secondary coil L2 may be set according to the target voltage conversion ratio of the second power conversion circuit 350a.

[0169] The second power conversion circuit 350a may include a third switch Q3 connected in series to the primary coil L1 between the fifth terminal P5 and the sixth terminal P6, and a fourth switch Q4 connected in series to the secondary coil L2 between the seventh terminal P7 and the eighth terminal P8. The third switch Q3 may include a third diode D3, and the fourth switch Q4 may include a fourth diode D4. For example, the third switch Q3 and the fourth switch Q4 may each be a FET and may include a body-diode-type third diode D3 and a body-diode-type fourth diode D4, respectively. In another example, the third switch Q3 and the fourth switch Q4 may each be a BJT, an IGBT, or a MOSFET.

[0170] The second power conversion circuit 350a may further include a third capacitor C3 between the fifth terminal P5 and the sixth terminal P6. The second power conversion circuit 350a may further include a fourth capacitor C4 between the seventh terminal P7 and the eighth terminal P8. The third capacitor C3 and / or the fourth capacitor C4 may be omitted.

[0171] The second power conversion circuit 350a can convert the first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6 into a third battery voltage V3, and output the third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8. For example, the battery controller 360 can adjust the level of the third battery voltage V3 by controlling the duty cycle of the first switch Q1.

[0172] The second power conversion circuit 350a can convert the third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8 into the first battery voltage V1, and output the first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6. For example, the battery controller 360 can adjust the levels of the first battery voltage V1 and the third battery voltage V3 by controlling the duty cycle of the second switch Q2.

[0173] For example, the first battery rack 310 may include twelve first battery modules connected in series, and each of the first battery modules may include twenty-two first battery cells connected in series. Each of the first battery cells may have a cell capacity of 94 Ah. The battery capacity of the first battery rack 310 may be 91.3 kWh. Depending on the state of charge of the first battery rack 310, the first battery voltage V1 of the first battery rack 310 may range from approximately 818.4 V to approximately 1095.6 V, for example.

[0174] The second battery rack 320 may include eleven second battery modules connected in series, and each of the second battery modules may include forty-four second battery cells connected in series and in parallel. Each of the second battery cells may have a cell capacity of 150 Ah. The battery capacity of the second battery rack 320 may be 267.2 kWh. Depending on the state of charge of the second battery rack 320, the second battery voltage V2 of the second battery rack 320 may range from approximately 750.2 V to approximately 1004.3 V, for example.

[0175] Battery module 340 may include forty-four third battery cells connected in series and in parallel. Each of the third battery cells may have a cell capacity of 150 Ah. The battery capacity of battery module 340 may be 24.3 kWh. The third battery voltage V3 of battery module 340 may be, for example, approximately 68.2 V to approximately 91.3 V, depending on the state of charge of battery module 340. The third battery cells and the second battery cells may be of the same type. Battery module 340 may include multiple battery modules connected in series and / or in parallel.

[0176] Depending on the first battery voltage V1 and the second battery voltage V2, the second conversion voltage V4 of the first power conversion circuit 330a may be approximately 68.2V to approximately 91.3V. The first power conversion circuit 330a may output the second conversion voltage V4 such that the ratio of the first conversion voltage V3 to the second conversion voltage V4 is 1:1. The step-up ratio of the first power conversion circuit 330a may be approximately 1:1 and may be controlled by the battery controller 360 based on the first battery current i1 and the second battery current i2. For example, the first power conversion circuit 330a may have a power conversion capacity of approximately 15kW.

[0177] The second power conversion circuit 350a can convert the first battery voltage V1 into a third battery voltage V3. The step-down ratio of the first power conversion circuit 330a can be approximately 12:1, and the step-down ratio of the second power conversion circuit 350a can be adjusted by the battery controller 360 according to the third state of charge of the battery module 340. For example, the second power conversion circuit 350a can have a power conversion capacity of approximately 550W.

[0178] Figure 8 It shows Figure 6 A circuit diagram of another example of a battery pack 300 is shown in FIG.

[0179] refer to Figure 8 , the battery pack 300b may include a first battery rack 310 connected between a first group of terminals 301 and a second group of terminals 302 and having a first battery voltage V1, a second battery rack 320 having a second battery voltage V2, a first power conversion circuit 330b having first to fourth terminals P1, P2, P3, and P4, a battery module 340 having a third battery voltage V3, and a second power conversion circuit 350b having fifth to eighth terminals P5, P6, P7, and P8. Although Figure 8 3. However, the battery pack 300b may further include a battery controller 360 (see FIG. Figure 6 ), the battery controller 360 is configured to control the first power conversion circuit 330b and the second power conversion circuit 350b. The battery pack 300b may further include a first current sensor 311 (reference Figure 6 ) and the second current sensor 321 (reference Figure 6 ).

[0180] The first power conversion circuit 330b may be a DC / DC converter. The first terminal P1 and the second terminal P2 may be connected to the positive terminal and the negative terminal of the battery module 340, respectively. The third terminal P3 may be connected to the negative terminal of the second battery rack 320. The fourth terminal P4 may be connected to the second group of terminals 302.

[0181] The second power conversion circuit 350b may be an isolated DC / DC converter. The second power conversion circuit 350b may be a flyback converter. The fifth terminal P5 and the sixth terminal P6 may be connected to the positive and negative terminals of the first battery rack 310, respectively, and the seventh terminal P7 and the eighth terminal P8 may be connected to the positive and negative terminals of the battery module 340, respectively.

[0182] The first power conversion circuit 330b may include an inductor L between a first terminal P1 and a first intermediate node N1, a first switch Q1 between the first intermediate node N1 and a third terminal P3, and a second switch Q2 between the first intermediate node N1 and a second intermediate node N2. The second intermediate node N2 may be commonly connected to the second terminal P2 and the fourth terminal P4.

[0183] The first switch Q1 may include a first diode D1, and the second switch Q2 may include a second diode D2. For example, the first switch Q1 and the second switch Q2 may each be an IGBT and may include a first diode D1 and a second diode D2 of a body diode type, respectively. In another example, the first switch Q1 and the second switch Q2 may each be a BJT, a FET, or a MOSFET.

[0184] The first power conversion circuit 330b may further include a second capacitor C2 between the third terminal P3 and the fourth terminal P4. The first power conversion circuit 330b may further include a first capacitor C1 between the first terminal P1 and the second terminal P2. In some embodiments, the first capacitor C1 may be omitted.

[0185] The first power conversion circuit 330b can convert the first conversion voltage V3 between the first terminal P1 and the second terminal P2 into a second conversion voltage V4, and output the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4. The first power conversion circuit 330b can convert the second conversion voltage V4 between the third terminal P3 and the fourth terminal P4 into a first conversion voltage V3, and output the first conversion voltage V3 between the first terminal P1 and the second terminal P2.

[0186] For example, if the second switch Q2 is turned on, current can flow from the first terminal P1 to the second terminal P2 through the inductor L and the second switch Q2, and energy stored in the first capacitor C1 and the battery module 340 can be accumulated in the inductor L. If the second switch Q2 is turned off, the energy accumulated in the inductor L can be moved to the second capacitor C2 through the first diode D1. Therefore, the first conversion voltage V3 between the first terminal P1 and the second terminal P2 can be converted into a second conversion voltage V4 between the third terminal P3 and the fourth terminal P4. The level of the second conversion voltage V4 can be adjusted according to the duty cycle of the second switch Q2. The battery controller 360 can adjust the level of the second conversion voltage V4 by controlling the duty cycle of the second switch Q2.

[0187] The second power conversion circuit 350b may include an additive polarity transformer TR, and the additive polarity transformer TR may include a primary coil L1 connected between the fifth terminal P5 and the sixth terminal P6, and a secondary coil L2 connected between the seventh terminal P7 and the eighth terminal P8. The ratio of the number of turns of the primary coil L1 to the number of turns of the secondary coil L2 may be set according to the target voltage conversion ratio of the second power conversion circuit 350b.

[0188] The second power conversion circuit 350b may include a third switch Q3 connected in series to the primary coil L1 between the fifth terminal P5 and the sixth terminal P6, and a fourth diode D4 connected in series to the secondary coil L2 between the seventh terminal P7 and the eighth terminal P8. The third switch Q3 may include a third diode D3. For example, the third switch Q3 may be a FET and may include a body diode type third diode D3. In another example, the third switch Q3 may be another type of transistor.

[0189] The second power conversion circuit 350b may further include a third capacitor C3 between the fifth terminal P5 and the sixth terminal P6. The second power conversion circuit 350b may further include a fourth capacitor C4 between the seventh terminal P7 and the eighth terminal P8. In some embodiments, the third capacitor C3 and / or the fourth capacitor C4 may be omitted.

[0190] The second power conversion circuit 350b can convert the first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6 into a third battery voltage V3, and output the third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8. For example, the battery controller 360 can adjust the level of the third battery voltage V3 by controlling the duty cycle of the first switch Q1.

[0191] The second power conversion circuit 350b can convert the third battery voltage V3 between the seventh terminal P7 and the eighth terminal P8 into the first battery voltage V1, and output the first battery voltage V1 between the fifth terminal P5 and the sixth terminal P6. For example, the battery controller 360 can adjust the levels of the first battery voltage V1 and the third battery voltage V3 by controlling the duty cycle of the second switch Q2.

[0192] For example, the first battery rack 310 may include twelve first battery modules connected in series, and each of the first battery modules may include twenty-two first battery cells connected in series. Each of the first battery cells may have a cell capacity of 94 Ah. The battery capacity of the first battery rack 310 may be 91.3 kWh. Depending on the state of charge of the first battery rack 310, the first battery voltage V1 of the first battery rack 310 may range from approximately 818.4 V to approximately 1095.6 V, for example.

[0193] The second battery rack 320 may include ten second battery modules connected in series, and each of the second battery modules may include forty-four second battery cells connected in series and in parallel. Each of the second battery cells may have a cell capacity of 150 Ah. The battery capacity of the second battery rack 320 may be 242.9 kWh. Depending on the state of charge of the second battery rack 320, the second battery voltage V2 of the second battery rack 320 may be, for example, approximately 683 V to approximately 913 V.

[0194] Battery module 340 may include forty-four third battery cells connected in series and in parallel. Each of the third battery cells may have a cell capacity of 150 Ah. The battery capacity of battery module 340 may be 24.3 kWh. The third battery voltage V3 of battery module 340 may be, for example, approximately 68.2 V to approximately 91.3 V, depending on the state of charge of battery module 340. The third battery cells and the second battery cells may be of the same type. Battery module 340 may include multiple battery modules connected in series and / or in parallel.

[0195] Depending on the first battery voltage V1 and the second battery voltage V2, the second conversion voltage V4 of the first power conversion circuit 330b may be approximately 136.4V to approximately 182.6V. The first power conversion circuit 330b may output the second conversion voltage V4 such that the ratio of the first conversion voltage V3 to the second conversion voltage V4 is 1:2. The step-up ratio of the first power conversion circuit 330b may be approximately 1:2 and may be controlled by the battery controller 360 based on the first battery current i1 and the second battery current i2. For example, the first power conversion circuit 330b may have a power conversion capacity of approximately 14kW.

[0196] The second power conversion circuit 350b can convert the first battery voltage V1 into a third battery voltage V3. The step-down ratio of the first power conversion circuit 330b can be approximately 12:1, and the step-down ratio of the second power conversion circuit 350b can be adjusted by the battery controller 360 according to the third state of charge of the battery module 340. For example, the second power conversion circuit 350b can have a power conversion capacity of approximately 550W.

[0197] The embodiments described herein with reference to the accompanying drawings are for illustrative purposes only and do not limit the scope of the present disclosure in any way. To simplify the description, conventional electronic configurations, control systems, software, and other functional aspects of the system may be omitted. In addition, the line connections or connecting members between the elements depicted in the drawings represent functional connections and / or physical or circuit connections by way of example, and in actual applications, they may be replaced or embodied as various additional functional connections, physical connections, or circuit connections.

[0198] In the description of the embodiment (especially, in the claims), the element mentioned with the definite article or indicative qualifier can be interpreted as one or more elements, even if it has a singular form. For example, unless otherwise defined, the scope defined herein is intended to include any embodiment in which the value in the scope is applied alone, and can be considered to be identical with the individual values ​​of the scope in the specific embodiment. The operation constituting the method of the present disclosure can be performed in an appropriate order, unless explicitly described or described in contrast with respect to the order. The present disclosure may not necessarily be limited to the order of the operation given in the description.

[0199] Unless limited by the appended claims, the examples or exemplary terms (such as, etc.) used herein are only used to describe the embodiments in detail and are not intended to limit the present disclosure. For example, it will be readily understood by those skilled in the art that many changes, combinations, and modifications may be made according to design conditions and factors within the scope of the appended claims and their equivalents.

[0200] The embodiments described herein are merely examples, and even if specific terms are used herein, these specific terms should be considered only in a general and descriptive sense, and not for the purpose of limitation. It will be apparent to those skilled in the art when submitting this application that, unless otherwise specifically stated, the features and / or elements described with respect to a particular embodiment may be used alone or in combination with the features and / or elements described with respect to other embodiments. Therefore, the scope of the present disclosure may not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0201] According to the present disclosure, a battery pack can be provided in which a plurality of battery racks are connected in parallel using a low-capacity power conversion circuit. The low-capacity power conversion circuit can be inexpensive and can generate a relatively small amount of heat during power conversion operation. The heat generated by the low-capacity power conversion circuit can be reduced, and thus the heat can have a small impact on the battery cells, and thus the low-capacity power conversion circuit and the battery cells can be arranged in the same space.

[0202] The capacity and output voltage range of the battery rack connected in series to the low-capacity power conversion circuit can be freely adjusted, thereby increasing the usability of the battery pack. For example, the number of battery modules contained in each of the battery racks can be unlimited.

[0203] However, the effects of the present disclosure are not limited thereto, and other effects of the present disclosure will be apparently understood by those skilled in the art through the above description.

[0204] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

1. A battery pack comprising: a first battery rack connected between the first set of terminals and the second set of terminals of the battery pack; The first power conversion circuit includes: First terminal; Second terminal; a third terminal; and a fourth terminal connected to the second set of terminals, wherein the first power conversion circuit is configured to bidirectionally convert a first converted voltage between the first terminal and the second terminal into a second converted voltage between the third terminal and the fourth terminal; a second battery rack connected between the first set of terminals and the third terminal of the first power conversion circuit; and A battery controller is configured to control the first power conversion circuit to adjust a level of the second conversion voltage.

2. The battery pack according to claim 1, wherein: The second battery rack is connected between the first terminal and the second terminal of the first power conversion circuit; the first terminal of the first power conversion circuit being connected to the first set of terminals; as well as The second terminal and the third terminal of the first power conversion circuit are connected to each other.

3. The battery pack according to claim 2, wherein: The first power conversion circuit further includes: a first switch between the first terminal of the first power conversion circuit and a first intermediate node; a second switch between the first intermediate node and the fourth terminal; and An inductor is provided between the first intermediate node and a second intermediate node of the first power conversion circuit, the second intermediate node being commonly connected to the second terminal and the third terminal of the first power conversion circuit.

4. The battery pack according to claim 2, wherein: The first power conversion circuit further includes: an adding polarity transformer comprising a primary coil connected between the first terminal and the second terminal and a secondary coil connected between the third terminal and the fourth terminal; a first switch connected in series to the primary coil between the first terminal and the second terminal; and A second switch is connected in series to the secondary coil between the third terminal and the fourth terminal.

5. The battery pack according to claim 1, wherein The first battery rack is connected between the first terminal and the second terminal of the first power conversion circuit; the first terminal of the first power conversion circuit being connected to the first set of terminals; as well as The second terminal and the fourth terminal of the first power conversion circuit are commonly connected to the second group of terminals.

6. The battery pack according to claim 5, wherein: The first power conversion circuit further includes: a first switch between the first terminal of the first power conversion circuit and a first intermediate node; an inductor between the first intermediate node and the third terminal; and A second switch is provided between the first intermediate node and a second intermediate node, wherein the second intermediate node is commonly connected to the second terminal and the fourth terminal.

7. The battery pack according to claim 1, further comprising: a battery module connected between the first terminal and the second terminal of the first power conversion circuit; as well as A second power conversion circuit includes a fifth terminal connected to the first group of terminals, a sixth terminal connected to the second group of terminals, a seventh terminal and an eighth terminal, and the second power conversion circuit is configured to bidirectionally convert the first battery voltage of the first battery rack connected between the fifth terminal and the sixth terminal into a third battery voltage of the battery module connected between the seventh terminal and the eighth terminal.

8. The battery pack according to claim 7, wherein: The first power conversion circuit further includes: a first switch between the first terminal and a first intermediate node; a second switch between the first intermediate node and the fourth terminal; and An inductor is provided between the first intermediate node and a second intermediate node, wherein the second intermediate node is commonly connected to the second terminal and the third terminal.

9. The battery pack according to claim 7, wherein: The second power conversion circuit further includes: an adding polarity transformer comprising a primary coil connected between the fifth terminal and the sixth terminal and a secondary coil connected between the seventh terminal and the eighth terminal; a third switch connected in series to the primary coil between the fifth terminal and the sixth terminal; and A fourth switch is connected in series to the secondary coil between the seventh terminal and the eighth terminal.

10. The battery pack according to claim 7, wherein: The first power conversion circuit further includes: an inductor between the first terminal and a first intermediate node; a first switch between the first intermediate node and the third terminal; and A second switch is provided between the first intermediate node and a second intermediate node, wherein the second intermediate node is commonly connected to the second terminal and the fourth terminal.

11. The battery pack according to claim 7, wherein: The second power conversion circuit further includes: an adding polarity transformer comprising a primary coil connected between the fifth terminal and the sixth terminal and a secondary coil connected between the seventh terminal and the eighth terminal; a third switch connected in series to the primary coil between the fifth terminal and the sixth terminal; and A diode is connected in series to the secondary winding between the seventh terminal and the eighth terminal in a reverse biased manner.

12. The battery pack according to claim 7, wherein: The battery controller is further configured to detect a third state of charge of the battery module and control the second power conversion circuit based on the third state of charge.

13. The battery pack according to claim 1, wherein The battery controller is further configured to detect a first state of charge of the first battery rack and a second state of charge of the second battery rack, and adjust the level of the second converted voltage based on a difference between the first state of charge and the second state of charge.

14. The battery pack according to claim 13, wherein: The battery controller is further configured to: if the second state of charge is less than the first state of charge in a charging mode, reduce a level of the second converted voltage to increase a charging current of the second battery rack; and The battery controller is further configured to reduce the level of the second converted voltage to reduce a discharge current of the second battery rack if the second state of charge is less than the first state of charge in a discharge mode.

15. The battery pack according to claim 1, wherein The battery controller is further configured to: detecting a first battery current capacity of the first battery rack and a second battery current capacity of the second battery rack; detecting a first battery current flowing through the first battery rack and a second battery current flowing through the second battery rack; as well as The level of the second conversion voltage is adjusted so that a ratio of the second battery current to the first battery current is equal to a ratio of the second battery current capacity to the first battery current capacity.

16. A battery pack comprising: a first battery rack connected between the first set of terminals and the second set of terminals and having a first battery voltage; The first power conversion circuit includes: First terminal; Second terminal; The third terminal; a fourth terminal; and a capacitor disposed between the third terminal and the fourth terminal, wherein the first power conversion circuit is configured to bidirectionally convert a first conversion voltage between the first terminal and the second terminal into a second conversion voltage between both ends of the capacitor; a second battery rack connected between the first group of terminals and the third terminal of the first power conversion circuit and having a second battery voltage; and a battery controller configured to control the first power conversion circuit to adjust a level of the second conversion voltage of the first power conversion circuit, The second battery rack and the capacitor of the first power conversion circuit are connected in series with each other between the first group of terminals and the second group of terminals.

17. The battery pack according to claim 16, wherein: The second battery rack is connected between the first terminal and the second terminal of the first power conversion circuit.

18. The battery pack according to claim 16, wherein: The first battery rack is connected between the first terminal and the second terminal of the first power conversion circuit.

19. The battery pack according to claim 16, further comprising: a battery module connected between the first terminal and the second terminal of the first power conversion circuit and having a third battery voltage; as well as a second power conversion circuit including a fifth terminal connected to the first group of terminals, a sixth terminal connected to the second group of terminals, a seventh terminal connected to the first terminal, and an eighth terminal connected to the second terminal, the second power conversion circuit being configured to bidirectionally convert the first battery voltage between the fifth terminal and the sixth terminal into the third battery voltage between the seventh terminal and the eighth terminal.

20. The battery pack according to claim 16, wherein The battery controller is further configured to detect a first battery current flowing through the first battery rack and a second battery current flowing through the second battery rack, and to adjust a level of the second conversion voltage based on a ratio of the second battery current to the first battery current and a ratio of a second battery capacity of the second battery rack to a first battery capacity of the first battery rack.

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