Energy storage system

Abstract

An energy storage device according to one embodiment of the present invention comprises: a plurality of battery modules connected in series; and a power conversion unit which are connected to the plurality of battery modules and which charge or discharge the plurality of battery modules, wherein each of the plurality of battery modules includes: a first switch connected to a (+) terminal or a (-) terminal of the battery module in series; a second switch for connecting the (+) terminal and the (-) terminal of the battery module; and a diode for connecting the (+) terminal and the (-) terminal of the battery module.

Description

energy storage devices

[0001] The present invention relates to an energy storage device, and more specifically, to an energy storage device capable of individual control of a plurality of battery modules.

[0002] Typically, energy storage devices containing multiple batteries utilize multiple batteries connected in series. If one battery fails, the entire battery is affected. For example, if one battery module becomes unusable, the remaining batteries also become unusable.

[0003] Recently, the use of reused batteries from electric vehicles for energy storage devices has been increasing. However, reused batteries vary in condition, and when connected in series, the system operates based on the battery with the lowest condition, making them inefficient. Connecting batteries in parallel rather than in series and connecting individual DC-DC converters to each battery allows for individual control. However, the application of individual DC-DC converters leads to higher system costs, complex configurations, and lower efficiency.

[0004] The technical problem to be solved by the present invention is to provide an energy storage device capable of individual control of a plurality of battery modules.

[0005] In order to solve the above technical problem, an energy storage device according to one embodiment of the present invention includes a plurality of battery modules connected in series; and a power conversion unit connected to the plurality of battery modules and charging or discharging the plurality of battery modules, wherein each battery module of the plurality of battery modules includes a first switch connected in series with a (+) terminal or a (-) terminal of the battery module; a second switch connecting the (+) terminal and the (-) terminal of the battery module; and a diode connecting the (+) terminal and the (-) terminal of the battery module.

[0006] Additionally, the diode may have a cathode connected to the (+) terminal of the battery module and an anode connected to the (-) terminal of the battery module.

[0007] Additionally, in the charging mode, the battery module being charged among the plurality of battery modules may have the first switch turned on and the second switch turned off.

[0008] Additionally, in the charging mode, among the plurality of battery modules, a battery module that has completed charging may have the first switch turned off and the second switch turned on.

[0009] Additionally, in the discharge mode, the battery module being discharged among the plurality of battery modules may have the first switch turned off and the second switch turned on.

[0010] Additionally, in the discharge mode, the battery module among the plurality of battery modules in which discharge is completed may have the first switch and the second switch turned off.

[0011] Additionally, each of the above battery modules may include a battery management unit that manages the status of the battery module.

[0012] In addition, the power conversion unit includes a control unit that controls the first switch and the second switch, and the control unit can receive information from the battery management unit and control the first switch and the second switch.

[0013] In addition, the power conversion unit may include a first power conversion unit that converts an AC voltage into a first DC voltage; and a second power conversion unit that converts the first DC voltage output from the first power conversion unit into a second DC voltage to charge at least one battery module among the plurality of battery modules or discharge the voltage of the battery module.

[0014] In addition, it includes a balancing unit connected to the plurality of battery modules, and the balancing unit can perform balancing between the plurality of battery modules by charging or discharging at least one battery module among the plurality of battery modules.

[0015] In addition, when the balancing unit operates, a battery module among the plurality of battery modules that is being charged or discharged may have the first switch turned on and the second switch turned off, and a battery module among the plurality of battery modules that is not being charged or discharged may have the first switch turned off and the second switch turned on.

[0016] Additionally, the power conversion unit and the balancing unit may have operating times that do not overlap with each other.

[0017] In addition, the battery module is connected in series or in parallel with another energy storage device, and the voltage discharged from the battery module when the balancing unit operates is applied to the power conversion unit of the other energy storage device to charge multiple battery modules of the other energy storage device.

[0018] In addition, it is connected in series or parallel with another energy storage device, and the power conversion unit can operate independently of the power conversion unit of the other energy storage device.

[0019] According to embodiments of the present invention, individual control of multiple batteries is possible using a simple structure. Furthermore, connecting multiple batteries in series enables efficient control and facilitates balancing between batteries.

[0020] FIG. 1 is a block diagram of an energy storage device according to one embodiment of the present invention.

[0021] Figures 2 to 5 are block diagrams of an energy storage device according to an embodiment of the present invention.

[0022] Figure 6 illustrates an implementation example of an energy storage device according to an embodiment of the present invention.

[0023] FIG. 7 is a block diagram of an energy storage device including a balancing unit according to an embodiment of the present invention.

[0024] FIG. 8 is a drawing for explaining the balancing operation of an energy storage device according to an embodiment of the present invention.

[0025] FIG. 9 is a block diagram of an energy storage device connected to another energy storage device according to an embodiment of the present invention, and FIG. 10 illustrates an implementation example thereof.

[0026] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0027] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0028] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0029] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0030] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0031] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0032] And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

[0033] Additionally, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

[0034] FIG. 1 is a block diagram of an energy storage device according to an embodiment of the present invention. FIGS. 2 to 5 are block diagrams of an energy storage device according to an embodiment of the present invention, FIG. 6 illustrates an implementation example of an energy storage device according to an embodiment of the present invention, FIG. 7 is a block diagram of an energy storage device including a balancing unit according to an embodiment of the present invention, FIG. 8 is a diagram for explaining a balancing operation of an energy storage device according to an embodiment of the present invention, FIG. 9 is a block diagram of an energy storage device connected to another energy storage device according to an embodiment of the present invention, and FIG. 10 illustrates an implementation example thereof.

[0035] An energy storage device (100) according to one embodiment of the present invention includes a plurality of battery modules (110) and a power conversion unit (120), and may include a balancing unit (130).

[0036] A plurality of battery modules (110) may include two or more battery modules, and the plurality of battery modules may be connected in series. The battery module may include an energy storage device and may include a battery management unit (115) that manages the state of the battery, which is an energy storage device. The battery management unit (115) may include a battery management system (BMS). The battery management unit (115) may measure and manage the state of charge (SOC, State of Charge), state of health (SOH, State of Health), etc. of the battery.

[0037] The power conversion unit (120) is connected to a plurality of battery modules (110) and charges or discharges the plurality of battery modules (110). The power conversion unit (120) can convert the voltage of power input from an external power source to charge the plurality of battery modules (110) or convert the voltage of the plurality of battery modules (110) and output it to the outside. The power conversion unit (120) can convert the voltage of power input from a grid or a solar power generation PV module, and can convert the voltage of the plurality of battery modules (110) and supply it to a load.

[0038] The power conversion unit (120) may include a first power conversion unit (122) and a second power conversion unit (123).

[0039] The first power conversion unit (122) can convert an AC voltage into a first DC voltage. Since the plurality of battery modules (110) are charged with a DC voltage, when an AC voltage is input from an external source such as a grid, the first power conversion unit (122) can be included to convert the AC voltage into the first DC voltage. Here, the first power conversion unit (122) can include a DC-AC converter, an AC-DC converter, or an AC-DC bidirectional converter.

[0040] The second power conversion unit (123) can convert the first DC voltage output from the first power conversion unit (122) into a second DC voltage. The second power conversion unit (123) is connected to a plurality of battery modules (110) and can charge at least one battery module among the plurality of battery modules or discharge the voltage of the battery module. The first DC voltage output from the first power conversion unit (122) can be converted into a second DC voltage suitable for charging the battery. In addition, the voltage output from the plurality of battery modules (110) can be converted into a voltage required for the load. Here, the second power conversion unit (123) may include a bidirectional converter as a DC-DC converter.

[0041] As shown in Fig. 5, the first power conversion unit (122) and the second power conversion unit (123) are connected in series, and can be connected to the second power conversion unit (123) and a plurality of battery modules (110).

[0042] A plurality of battery modules (110) connected in series are connected to one power conversion unit (120), and in order to individually control each battery module (111), each battery module (111) of the plurality of battery modules (110) may include a first switch (112), a second switch (113), and a diode (114).

[0043] The state of charge and health of each battery module (110) may vary depending on the state of each battery module. If the battery module with the worst state is operated based on this, battery efficiency may decrease. Therefore, individual control is required when charging and discharging the battery modules. To this end, each battery module (111) may include a first switch (112), a second switch (113), and a diode (114).

[0044] The first switch (112) may be connected in series with the (+) terminal or the (-) terminal of the battery module (111). The first switch (112) may be connected in series with the (+) terminal of the battery module (111), as shown in FIG. 2, or may be connected in series with the (-) terminal of the battery module (111), as shown in FIG. 3. The first switch (112) may include a FET, a transistor, a relay, a physical switch, or the like. The first switch (112) may be connected in series with the (+) terminal or the (-) terminal of the battery module (111), and when the first switch (112) is turned on, the battery module (111) may be connected to the power conversion unit (120) or another battery module, and when the first switch (112) is turned off, the connection with the power conversion unit (120) or another battery module may be disconnected.

[0045] The second switch (113) can connect the (+) terminal and the (-) terminal of the battery module (111). The second switch (113) can include a FET, a transistor, a relay, a physical switch, etc. The second switch (113) can connect or disconnect the (+) terminal and the (-) terminal of the battery module (111). When the second switch (113) is turned on, the (+) terminal and the (-) terminal of the battery module (111) are connected, thereby allowing the battery module (111) to be bypassed. When the second switch (113) is turned off, the direct connection between the (+) terminal and the (-) terminal of the battery module (111) can be disconnected.

[0046] The diode (114) can connect the (+) terminal and the (-) terminal of the battery module (111). At this time, the cathode of the diode (114) can be connected to the (+) terminal of the battery module (111), and the anode can be connected in a direction connected to the (-) terminal of the battery module (111). Through this, current can flow from the (-) terminal of the battery module (111) to the (+) terminal.

[0047] The second switch (113) and diode (114) can be implemented as a MOSFET including a diode.

[0048] The first switch (112), the second switch (113), and the diode (114) may be formed to be connected to the power line side of the battery module (111), as shown in FIG. 6. Alternatively, they may be formed on the substrate of the battery management unit (115). For example, they may be formed on the BMS board.

[0049] The power conversion unit (120) may include a first switch (112) and a second switch (113) and a control unit (121). As shown in FIG. 4, the control unit (121) included in the power conversion unit (120) may receive information from the battery management unit (115) and control the first switch (112) and the second switch (113) to individually control the battery module (111). Alternatively, the control unit may be configured as an external upper controller or a separate module, and the upper controller or the separate control unit may receive information from the battery management unit (115) and control the first switch (112) and the second switch (113) to individually control the battery module (111). In addition, the battery management unit (115) of the battery module (111) may control the first switch (112) and the second switch (113).

[0050] It may include a charging mode for charging a plurality of battery modules (110) and a discharging mode for discharging a plurality of battery modules (110).

[0051] In the charging mode, among the plurality of battery modules (110), the battery module being charged may have its first switch (112) turned on and its second switch (113) turned off. When all battery modules of the plurality of battery modules (110) are charged, the first switch (112) of each battery module may be controlled to be turned on and its second switch (113) to be turned off. Through this, the power conversion unit (120) and each battery module may be connected in series, and the voltage output from the power conversion unit (120) may be applied to each battery module to charge the battery module.

[0052] In the charging mode, among the plurality of battery modules (110), a battery module that has completed charging may have its first switch (112) turned off and its second switch (113) turned on. The charging state or charging speed may be different for each of the plurality of battery modules (110), and the time until charging is completed may be different. Here, the completed charging state may be a state charged at the maximum voltage or a state charged above a preset charging voltage. If a battery module that has completed charging before other battery modules continues to be charged, a fire may occur or the SOH may deteriorate due to overcharging. Therefore, in order to prevent overcharging, charging for the corresponding battery module must be stopped. To this end, the battery module that has completed charging may be individually controlled so that its first switch (112) is turned off and its second switch (113) is turned on. The first switch (112) is turned off to block the voltage from being applied to the corresponding battery module, but the second switch (113) is turned on to bypass the corresponding battery module and allow the voltage to be applied to other battery modules that have not yet been fully charged.

[0053] In the discharge mode, among the plurality of battery modules (110), the first switch (112) of the battery module being discharged may be turned off and the second switch (113) may be turned on. When all battery modules of the plurality of battery modules (110) are discharged, the first switch (112) of each battery module may be turned off and the second switch (113) may be controlled to be turned on. Through this, the power conversion unit (120) and each battery module are connected in series, and the voltage of each battery module may be applied to the power conversion unit (120) to discharge the battery module.

[0054] In the discharge mode, among the plurality of battery modules (110), a battery module whose discharge has been completed may have its first switch (112) and its second switch (113) turned off. The charging state or discharge speed may be different for each of the plurality of battery modules (110), and the time at which discharge is completed may be different. Here, the state in which discharge is completed may be a completely discharged state, or a state in which discharge is below a preset discharge voltage. If a battery module whose discharge is completed before other battery modules continues to discharge, its SOH may deteriorate due to over-discharge. Therefore, in order to prevent over-discharge, the discharge for the corresponding battery module must be stopped. To this end, the battery module whose discharge has been completed may be individually controlled so that its first switch (112) and its second switch (113) are turned off. The first switch (112) and the second switch (113) are turned off to cut off the connection with the corresponding battery module, and a bypass path may be formed through the diode (114). Here, the flow of current in the bypass path formed through the diode (114) during discharge may be opposite to the flow of current in the bypass path formed when the second switch (113) is turned on. That is, by maintaining the path in the direction of discharge through the diode (114), it is possible to allow discharge of other battery modules that have not yet completed discharge.

[0055] The balancing unit (130) may be connected to a plurality of battery modules (110). The balancing unit (130) may charge or discharge at least one battery module among the plurality of battery modules (110) to perform balancing among the plurality of battery modules (110). The balancing unit (130) may be connected in parallel with the power conversion unit (120), as shown in FIG. 7. As shown in FIG. 8, it may be connected in parallel with the second power conversion unit (123). In addition to the charging mode and discharging mode described above, a balancing mode in which the plurality of battery modules (110) perform balancing through the balancing unit (130) may be included.

[0056] The balancing unit (130) can convert the voltage applied from an external power source or the first power conversion unit (122) to charge the battery module (116) that needs to be charged for balancing. Alternatively, the balancing unit (130) can convert the voltage of the battery module (116) that needs to be discharged for balancing and output it to a load or another energy storage device (100). The step-up or step-down ratios of the power conversion unit (120) and the balancing unit (130) may be different from each other. For example, the step-up or step-down ratio of the balancing unit (130) may be smaller than the step-up or step-down ratio of the power conversion unit (120). Alternatively, the step-up or step-down ratio of the balancing unit (130) may be larger than the step-up or step-down ratio of the power conversion unit (120). Additionally, it is natural that the step-up or step-down ratios of the power conversion unit (120) and the balancing unit (130) may be the same.

[0057] When the balancing unit operates, a battery module (116) among the plurality of battery modules (110) that is being charged or discharged may have the first switch (112) turned on and the second switch (113) turned off, and a battery module among the plurality of battery modules (110) that is not being charged or discharged may have the first switch (112) turned off and the second switch (113) turned on.

[0058] In balancing mode, the balancing operation can be performed by discharging a battery module with a higher charge amount than other battery modules or charging a battery module with a higher discharge amount, depending on the charge status, in order to balance between battery modules. Alternatively, it can be performed by discharging some and charging some. At this time, only the battery module (116) to be balanced can be connected to the balancing unit (130) so that charging and discharging can be performed for the battery module (116), and the connection of other battery modules can be disconnected. To this end, the first switch (112) of the battery module (111) can be controlled to be on and the second switch (113) to be off, and the first switch (112) of the other battery modules can be controlled to be off and the second switch (113) to be on. Through this, only the battery module (116) can be connected to the balancing unit (130), and the other battery modules can be bypassed.

[0059] As shown in Fig. 8, balancing can be performed by turning on the first switch (112) and turning off the second switch (113) for the battery module (116) to be balanced, and turning off the first switch (112) and turning on the second switch (113) for the other battery modules to form a balancing path (131) passing through the corresponding battery module (116).

[0060] Alternatively, when a discharge is required for the battery module (116), the first switch (112) for the battery module (116) may be turned on and the second switch (113) may be turned off, and the first switch (112) and the second switch (113) for the other battery modules may be turned off to form a balancing path passing through the diodes (114) of the battery module (116) and the other battery modules. That is, when charging is required for the battery module (116), the first switch (112) for the battery module (116) to be balanced is turned on and the second switch (113) is turned off, and other battery modules turn off the first switch (112) and turn on the second switch (113), thereby forming a balancing path (131) passing through the battery module (116). When discharging is required for the battery module (116), the first switch (112) for the battery module (116) to be balanced is turned on and the second switch (113) is turned off, and other battery modules turn off the first switch (112) and the second switch (113), thereby forming a balancing path passing through the battery module (116).

[0061] The power conversion unit (120) and the balancing unit (130) may have operating times that do not overlap each other. Since the connection relationship of the plurality of battery modules (110) when the power conversion unit (120) charges or discharges the plurality of battery modules (110) and the connection relationship of the plurality of battery modules (110) when the balancing unit (130) performs a balancing operation on a specific battery module (116) are different, the power conversion unit (120) and the balancing unit (130) may not operate simultaneously. That is, when the power conversion unit (120) charges or discharges the plurality of battery modules (110), the balancing unit (130) may not operate. The balancing unit (130) may perform a balancing operation during the time when the power conversion unit (120) does not charge or discharge the plurality of battery modules (110).

[0062] The energy storage device (100) according to an embodiment of the present invention may be connected in series or in parallel with other energy storage devices. As shown in FIG. 9, the other energy storage device may also include a power conversion unit (210) connected to a plurality of battery modules (220) and may include a balancing unit (230). At this time, a plurality of second power conversion units (123, 223) may be connected to one first power conversion unit (122). As shown in FIG. 10, a plurality of DC-DC converters, which are second power conversion units, may be connected in parallel to one DC-AC converter, which is the first power conversion unit (122).

[0063] When the balancing unit (130) operates, the voltage discharged from the battery module (116) can be applied to the power conversion unit (210) of another energy storage device to charge multiple battery modules (220) of the other energy storage device. By using the voltage discharged for balancing, the battery modules of the other energy storage device can be charged, thereby increasing battery efficiency.

[0064] The power conversion unit (110) can operate independently from the power conversion units (210) of other energy storage devices. For example, each power conversion unit can operate individually or simultaneously. They can operate individually depending on the voltage applied from the outside or the voltage required by the load. In an energy storage device where the power conversion unit is not operating, the balancing unit can operate to perform a balancing operation.

[0065] As described above, individual control of battery modules is possible with only two switches and diodes for a plurality of battery modules connected in series, and the disadvantages of complexity of configuration, price competitiveness, and reduced efficiency can be resolved.

[0066] Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from the essential characteristics of the above-described description. Therefore, the disclosed methods should be considered illustrative rather than restrictive. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. Multiple battery modules connected in series; and It includes a power conversion unit that is connected to the plurality of battery modules and charges or discharges the plurality of battery modules, Each battery module of the above plurality of battery modules, A first switch connected in series with the (+) terminal or the (-) terminal of the above battery module; A second switch connecting the (+) terminal and the (-) terminal of the above battery module; and An energy storage device including a diode connecting the (+) terminal and the (-) terminal of the above battery module.

2. In paragraph 1, The above diode, An energy storage device in which the cathode is connected to the (+) terminal of the battery module and the anode is connected to the (-) terminal of the battery module.

3. In paragraph 1, In charging mode, the battery module being charged among the plurality of battery modules is: An energy storage device wherein the first switch is on and the second switch is off.

4. In paragraph 1, In charging mode, an energy storage device in which a battery module among the plurality of battery modules has completed charging, wherein the first switch is off and the second switch is on.

5. In paragraph 1, In the discharge mode, the energy storage device in which the battery module being discharged among the plurality of battery modules is the first switch is off and the second switch is on.

6. In paragraph 1, In discharge mode, an energy storage device in which a battery module among the plurality of battery modules has completed discharging, wherein the first switch and the second switch are turned off.

7. In paragraph 1, It includes a balancing unit connected to the plurality of battery modules, The above balancing part, An energy storage device that performs balancing between the plurality of battery modules by charging or discharging at least one battery module among the plurality of battery modules.

8. In paragraph 7, When the above balancing part operates, Among the plurality of battery modules, the battery module being charged or discharged has the first switch turned on and the second switch turned off, An energy storage device in which the battery module among the plurality of battery modules is not charged or discharged, wherein the first switch is off and the second switch is on.

9. In paragraph 7, The above power conversion unit and the above balancing unit, An energy storage device having non-overlapping operating times.

10. In paragraph 7, Connected in series or parallel with other energy storage devices, An energy storage device in which the voltage discharged from the battery module when the above balancing unit operates is applied to the power conversion unit of the other energy storage device to charge multiple battery modules of the other energy storage device.

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