Energy Storage System

Abstract

To provide a power storage system to effectively charge each of different types of battery packs connected in parallel.SOLUTION: A power storage system includes: a power conversion device to which power is supplied from an external system; and a controller that controls an operation of the power conversion device. First and second battery packs different from each other in type are connected to the power conversion device in parallel. The controller stores a first charge profile for the first battery pack and a second charge profile for the second battery pack. The controller charges the first battery pack by operating the power conversion device based on the first charge profile. The controller charges the second battery pack by operating the power conversion device based on the second charge profile.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electricity storage system. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2014-103804 (Patent Document 1) discloses a battery system in which a plurality of assembled batteries are connected in parallel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-103804 A [Patent Document 2] JP 2013-169051 A [Patent Document 3] JP 2012-85487 A [Patent Document 4] JP 2011-188700 A [Patent Document 5] JP 2010-142040 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a system such as that disclosed in Patent Document 1, the multiple assembled batteries may be of different types. In such a case, it is desirable to efficiently charge the assembled batteries.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to efficiently charge each assembled battery in a power storage system in which different types of assembled batteries are connected in parallel. [Means for solving the problem]

[0006] According to an aspect of the present disclosure, a power storage system includes a power conversion device to which power is supplied from an external system, and a control device that controls operation of the power conversion device. A first and a second assembled battery of different types are connected in parallel to the power conversion device. The control device stores a first charging profile for the first assembled battery and a second charging profile for the second assembled battery. The control device charges the first assembled battery by operating the power conversion device based on the first charging profile. The control device charges the second assembled battery by operating the power conversion device based on the second charging profile.

[0007] According to the above configuration, the first assembled battery is charged using the first charging profile for the first assembled battery, and the second assembled battery is charged using the second charging profile for the second assembled battery. Therefore, in a power storage system in which different types of assembled batteries are connected in parallel, each assembled battery can be efficiently charged.

[0008] Preferably, the power conversion device has a first terminal and a second terminal. One of the first and second assembled batteries is connected to the first terminal. The other of the first and second assembled batteries is connected to the second terminal. The control device acquires identification information for identifying the types of the assembled batteries connected to the first terminal and the second terminal, respectively. The control device selects, from the first and second charging profiles, a charging profile used to charge the assembled battery connected to the first terminal and a charging profile used to charge the assembled battery connected to the second terminal, based on the identification information. The control device operates the power conversion device based on each selected charging profile, thereby charging the assembled battery connected to the first terminal and the assembled battery connected to the second terminal.

[0009] According to the above configuration, the control device can identify the type of the battery pack connected to the first terminal and the second terminal, making it possible to charge each battery pack based on an appropriate charging profile.

[0010] Preferably, the first assembled battery is a ternary lithium ion battery, and the second assembled battery is an iron phosphate lithium ion battery.

[0011] According to the above configuration, in a power storage system in which a ternary battery and an LFP battery are connected in parallel, each assembled battery can be efficiently charged. Effect of the Invention

[0012] According to the above disclosure, in a power storage system in which different types of assembled batteries are connected in parallel, it becomes possible to efficiently charge each assembled battery. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram for explaining configurations of a power storage system and an external system. [Diagram 2] FIG. 4 is a block diagram for explaining a charging process in a battery unit. [Diagram 3] FIG. 4 is a flow chart illustrating a flow of processing executed in the power storage system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the same members are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0015] Fig. 1 is a diagram for explaining the configuration of a power storage system and an external system. As shown in Fig. 1, a power storage system 1 is connected to an external system 900 via a power line. The power storage system 1 can be supplied with power from the external system 900 and can be discharged to the external system 900.

[0016] The power storage system 1 includes a plurality of battery units 10A, 10B, ... and a host controller 20. In the following, any one of the plurality of battery units 10A, 10B, ... will also be referred to as a "battery unit 10".

[0017] The battery unit 10A includes a PCU (Power Control Unit) 11, a ternary lithium ion battery (hereinafter referred to as a "ternary battery") 12A, two iron phosphate lithium ion batteries (hereinafter referred to as "LFP batteries") 12B, and an ECU (Electronic Control Unit) 13. The PCU 11 is a power conversion device including an inverter, a DC / DC converter, etc. In the battery unit 10A, one ternary battery 12A and two LFP batteries 12B are connected in parallel to the PCU 11.

[0018] Specifically, the PCU 11 has three terminals 111, 112, and 113 for external connection. Of the three terminals, the terminals 111 and 112 are connected to the LFP battery 12B, and the terminal 113 is connected to the ternary battery 12A.

[0019] The battery unit 10B includes a PCU 11, two ternary batteries 12A, one LFP battery 12B, and an ECU 13. In the battery unit 10B, the two ternary batteries 12A and one LFP battery 12B are connected in parallel to the PCU 11. The ternary battery 12A is connected to terminals 111 and 113, and the LFP battery 12B is connected to terminal 112. The combination of batteries connected to the PCU 11 in the battery unit 10B is different from that in the battery unit 10A.

[0020] Each of the ternary battery 12A and the LFP battery 12B is an example of an assembled battery (also referred to as a "battery pack") in which a plurality of the same type of unit cells are packed together. The battery unit 10 includes three assembled batteries connected in parallel to the PCU 11. The power storage system 1 may include a battery unit 10 including only three ternary batteries 12A, or a battery unit 10 including only three LFP batteries 12B.

[0021] In this example, a PCU and an ECU that were installed in a vehicle are repurposed as the PCU 11 and the ECU 13, respectively. Similarly, a battery pack that was installed in a vehicle is repurposed as the ternary battery 12A and the LFP battery 12B. In this manner, the energy storage system 1 is constructed using unnecessary vehicle parts. In detail, the three-phase AC motor connected to the vehicle's PCU is removed, and three battery packs (one each for the U layer, V layer, and W layer) are connected. Note that terminals 111, 112, and 113 are terminals for the U layer, the V layer, and the W layer, respectively.

[0022] The external system 900 includes a PCS (Power Conditioning System) 910, a solar power generation device 920, a load 930, and a power system 940. The battery units 10 (more specifically, the PCUs 11) are connected to the PCS 910 in parallel with each other.

[0023] The PCS 910 is a power conversion device capable of both AC / DC conversion (conversion from alternating current to direct current) and DC / AC conversion (conversion from direct current to alternating current). The PCS 910 receives direct current power from, for example, a solar power generation device 920. The PCS 910 supplies alternating current power to a load 930. The load 930 includes electrical appliances used in the home (for example, air conditioners and lighting fixtures). The PCS 910 exchanges alternating current power with a power grid 940.

[0024] Each ECU 13 includes a processor and a memory (see FIG. 2), and controls the battery unit 10. Each ECU 13 is connected to a host controller 20 so as to be able to communicate with the host controller 20.

[0025] The upper controller 20 includes a processor and a memory (neither of which are shown), and sends commands to each ECU 13. The upper controller 20 is communicatively connected to a server (not shown) via a network NW.

[0026] In the power storage system 1, each battery unit 10 is charged by the external system 900 at least during the night hours, and discharges to the external system 900 at least during the daytime hours. In detail, each battery unit 10 has three assembled batteries that are supplied with power from the external system 900 at least during the night hours, and discharges to the external system 900 at least during the daytime hours.

[0027] However, the battery characteristics of the ternary battery 12A and the LFP battery 12B are different from each other. For example, the SOC-OCV characteristic, which is one of the battery characteristics, is different from each other between the ternary battery 12A and the LFP battery 12B. The OCV (V) of the ternary battery 12A is greater than the OCV (V) of the LFP battery 12B over the entire range of SOC (%). Note that SOC (State Of Charge) represents the charging state (charging rate) of the battery. OCV (Open Circuit Voltage) represents the open circuit voltage (open circuit voltage) of the battery.

[0028] Due to such differences in battery characteristics, charging ternary battery 12A and LFP battery 12B with a charging profile according to the type of battery is more efficient than charging ternary battery 12A and LFP battery 12B with the same charging profile. Therefore, in power storage system 1, ternary battery 12A and LFP battery 12B are charged using different charging profiles.

[0029] 2 is a block diagram for explaining the charging process in the battery unit 10 A. As shown in FIG.

[0030] The battery unit 10A acquires a charging profile P1 for a ternary battery, a charging profile P2 for an LFP battery, and identification information DA indicating the battery type in the battery unit 10A from the upper controller 20. The charging profiles P1, P2, and the identification information DA are stored in the memory 132.

[0031] A program R is pre-installed in the memory 132. The program R may be configured to be transmitted from the upper controller 20 to the ECU 13. Note that the charging profiles P1, P2 and the identification information DA may be pre-stored in the memory 132 without going through the upper controller 20.

[0032] The charging profiles P1 and P2 are data (files) in which various settings for charging are written. The charging profile P1 is configured to be suitable for charging a ternary battery. The charging profile P2 is configured to be suitable for charging an LFP battery.

[0033] In this example, the charging profile P1 is a profile for performing constant current constant voltage charging (CCCV: Constant Current Constant Voltage) that manages voltage and current. The relationship between voltage and current is specified in the charging profile P1. In detail, in the case of charging from a discharged state, the battery pack is charged in a constant current state since the voltage is low at first, and then the charging amount gradually increases and when the cell voltage reaches a predetermined voltage, the charging is switched to constant voltage charging. In the charging profile P1, after switching to constant voltage charging, the amount of current is reduced so that the predetermined voltage is not exceeded. Note that full charge is determined from the charging time and the reduction state of the charging current.

[0034] In this example, the charging profile P2 is a profile that manages the voltage. More specifically, the charging profile P2 is a profile that manages the charging capacity in addition to the voltage.

[0035] The program R is configured to execute charging control in accordance with the charging profiles P1 and P2. The program R is executed by the processor 131 to generate a control command based on the charging profiles P1 and P2, and to send the control command to the PCU 11.

[0036] The processor 131 refers to the identification information DA and sends a control command according to the type of battery pack to each battery pack in the battery unit 10A. More specifically, the identification information DA is information for identifying the type of battery pack connected to each of the three terminals 111-113 of the battery unit 10A. In this example, the identification information DA indicates that an LFP battery 12B is connected to the first terminal indicating terminal 111 and the second terminal indicating terminal 112, and that a ternary battery 12A is connected to the third terminal indicating terminal 113.

[0037] The processor 131 determines the type of the assembled battery connected to each of the three terminals 111 to 113 based on the identification information DA. As a result, the processor 131 selects, from among the charging profile P1 and the charging profile P2, a charging profile for the assembled battery connected to the terminal 111 (in this example, charging profile P2), a charging profile for the assembled battery connected to the terminal 112 (in this example, charging profile P2), and a charging profile for the assembled battery connected to the terminal 113 (in this example, charging profile P1).

[0038] The ECU 13 of the battery unit 10A operates the PCU 11 based on the selected charging profile to charge one ternary battery 12A and two LFP batteries 12B. In particular, as described above, the ECU 13 operates the PCU 11 based on the charging profile P2 to charge the LFP battery 12B connected to terminal 111 (first terminal) and the LFP battery 12B connected to terminal 112 (second terminal). The ECU 13 operates the PCU 11 based on the charging profile P1 to charge the ternary battery 12A connected to terminal 113 (third terminal).

[0039] The same processing as that of battery unit 10A is executed in battery unit 10B. In this case, upper controller 20 sends identification information DB to battery unit 10B instead of identification information DA. The identification information DB indicates that a ternary battery 12A is connected to each of a first terminal indicating terminal 111 and a third terminal indicating terminal 113, and that an LFP battery 12B is connected to a second terminal indicating terminal 112.

[0040] The ECU 13 of the battery unit 10B operates the PCU 11 based on the identification information DB to charge the two ternary batteries 12A and one LFP battery 12B (see FIG. 1). In more detail, the ECU 13 of the battery unit 10B operates the PCU 11 based on the charging profile P1 to charge the ternary battery 12A connected to terminal 111 and the ternary battery 12A connected to terminal 113. The ECU 13 of the battery unit 10B operates the PCU 11 based on the charging profile P2 to charge the LFP battery 12B connected to terminal 112.

[0041] For example, when the type of the battery pack connected to any of the terminals 111-113 of the battery unit 10A is changed due to replacement of the battery pack in the battery unit 10A, the upper controller 20 acquires new identification information DA' via the network NW. Note that the identification information DA' is generated, for example, by a user inputting data to a server device (not shown).

[0042] The upper controller 20 sends the identification information DA' to the ECU 13 of the battery unit 10A together with a command to update the identification information. The ECU 13 of the battery unit 10A updates the identification information DA with the identification information DA'. The ECU 13 of the battery unit 10A then determines what type of assembled battery is connected to each of the terminals 111-113 based on the identification information DA', and charges each assembled battery with the charging profiles P1, P2 corresponding to the type.

[0043] Fig. 3 is a flow diagram illustrating the flow of processing executed in the power storage system 1. In detail, Fig. 3 is a flow diagram illustrating the flow of processing executed in the battery unit 10A. Similar processing is also executed in the battery units 10 other than the battery unit 10A.

[0044] 3, in step S1, the ECU 13 of the battery unit 10A determines, based on the identification information DA, the type of battery pack connected to each of the three terminals 111-113. Specifically, the ECU 13 determines, for each of the three terminals 111-113, whether the battery pack connected to each of the three terminals 111-113 is a ternary battery 12A or an LFP battery 12B.

[0045] In step S2, the ECU 13 determines whether or not the charging start time has arrived. In more detail, the ECU 13 has a clock (not shown) and determines whether or not the charging start time has arrived based on the clock. An example of the charging start time is 6:00 p.m.

[0046] When the ECU 13 determines that the charging start time has arrived (YES in step S2), in step S3, it starts charging one ternary battery 12A by operating the PCU 11 based on charging profile P1, and starts charging two LFP batteries 12B by operating the PCU 11 based on charging profile P2.

[0047] In step S4, the ECU 13 determines whether each of the three battery packs is fully charged. If the ECU 13 determines that each of the three battery packs is fully charged (YES in step S4), the series of processes ends. If the ECU 13 determines that each of the three battery packs is not fully charged (NO in step S4), the ECU 13 continues charging each of the three battery packs until each of the three battery packs is fully charged.

[0048] <Summary> The electricity storage system 1 can be summarized as follows.

[0049] (1) The power storage system 1 includes a PCU 11 to which power is supplied from an external system 900, and an ECU 13 that controls the operation of the PCU 11. A ternary battery and an LFP battery, which are different types of battery, are connected in parallel to the PCU 11. The ECU 13 stores a charging profile P1 for the ternary battery and a charging profile P2 for the LFP battery. The ECU 13 operates the PCU 11 based on the charging profile P1 to charge the ternary battery 12A. The ECU 13 operates the PCU 11 based on the charging profile P2 to charge the LFP battery 12B.

[0050] According to the above configuration, the ternary battery 12A is charged using the charging profile P1 for the ternary battery, and the LFP battery 12B is charged using the charging profile P2 for the LFP battery. Therefore, in the power storage system 1 in which different types of assembled batteries (ternary battery 12A and LFP battery 12B) are connected in parallel, each assembled battery can be efficiently charged. For example, compared to a configuration in which the ternary battery 12A and the LFP battery 12B are charged using the same charging profile, according to the above configuration, the ternary battery 12A and the LFP battery 12B can be efficiently charged.

[0051] (2) PCU 11 has at least terminal 111 and terminal 112. One of ternary battery 12A and LFP battery 12B is connected to terminal 111, and the other of ternary battery 12A and LFP battery 12B is connected to terminal 112. ECU 13 acquires identification information that identifies the type of battery pack connected to each of terminals 111 and 112.

[0052] Based on the identification information, the ECU 13 selects, from the charging profile P1 and the charging profile P2, a charging profile to be used for charging the assembled battery connected to the terminal 111 and a charging profile to be used for charging the assembled battery connected to the terminal 112. The ECU 13 charges the assembled battery connected to the terminal 111 and the assembled battery connected to the terminal 112 by operating the PCU 11 based on each selected charging profile.

[0053] According to the above configuration, the ECU 13 can identify the type of the battery pack connected to the terminals 111 and 112, and therefore it becomes possible to charge each battery pack based on an appropriate charging profile.

[0054] <Modification> (1) In the above, a ternary battery and an LFP battery are used as examples of different types of assembled batteries, but the present invention is not limited to this. The above-described charging process can be performed on two or more types of assembled batteries with a charging profile suitable for each assembled battery.

[0055] (2) Although the above description has been given of an example in which three assembled batteries are connected to the power conversion device (PCU 11 in this example), the present invention is not limited to this example. For example, two or four or more assembled batteries may be connected to the power conversion device.

[0056] <Additional Notes> (1) A method for controlling charging in a power storage system in which power is stored by an external system, comprising the steps of: the power storage system includes a power conversion device to which power is supplied from an external system, and first and second assembled batteries of different types are connected in parallel to the power conversion device; The charging control method includes: A control device of the power storage system operates the power conversion device based on a charging profile for the first assembled battery, thereby charging the first assembled battery; and a step of the control device charging the second assembled battery by operating the power conversion device based on a charging profile for the second assembled battery.

[0057] (2) A program R that causes the processor 131 to execute each step of the charging control method described above.

[0058] (3) A non-transitory computer-readable storage medium storing the program R.

[0059] (4) A non-transitory computer-readable storage medium further storing the first and second profiles described above.

[0060] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the scope of the claims, and it is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. [Explanation of symbols]

[0061] 1 Energy storage system, 10A, 10B battery unit, 12A ternary battery, 12B LFP battery, 20 Upper controller, 111, 112, 113 terminal, 131 processor, 132 memory, 900 External system, 910 PCS, 920 Solar power generation device, 930 Load, 940 Power system.

Claims

1. a power conversion device to which power is supplied from an external system; A control device for controlling an operation of the power conversion device, The power conversion device includes first and second assembled batteries of different types connected in parallel to each other, The control device includes: a first charging profile for the first assembled battery and a second charging profile for the second assembled battery; Charging the first assembled battery by operating the power conversion device based on the first charging profile; Charging the second assembled battery by operating the power conversion device based on the second charging profile; the first assembled battery is a ternary lithium ion battery, the second assembled battery is an iron phosphate lithium ion battery, the first charging profile is a profile for performing constant-current constant-voltage charging that manages a voltage and a current, and defines a relationship between the voltage and the current; The second charging profile is a profile of a method for managing voltage and charging capacity.

2. The power conversion device has a first terminal and a second terminal, one of the first and second assembled batteries is connected to the first terminal, and the other of the first and second assembled batteries is connected to the second terminal; The control device includes: acquiring identification information for identifying a type of a battery pack connected to each of the first terminal and the second terminal; selecting, from the first and second charging profiles, a charging profile to be used for charging the assembled battery connected to the first terminal and a charging profile to be used for charging the assembled battery connected to the second terminal, based on the identification information; 2. The power storage system according to claim 1, wherein the power conversion device is operated based on each of the selected charging profiles to charge the assembled battery connected to the first terminal and the assembled battery connected to the second terminal.

3. The control device when one of the first and second assembled batteries is replaced with a third assembled battery of the same type as the other assembled battery, the identification information after the replacement is further acquired; reselecting each of the charging profiles based on the identification information acquired after the replacement; 3. The power storage system according to claim 2, wherein the power conversion device is operated based on each of the reselected charging profiles, thereby charging the assembled battery connected to the first terminal and the assembled battery connected to the second terminal.

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