JP2015008040A - Secondary battery device, and module connection discrimination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a battery management unit to automatically detect parallel and serial connection states of a battery module.SOLUTION: A secondary battery device comprises: a plurality of battery modules; and a battery management unit determining individual battery modules by identifiers allocated to the plurality of battery modules, and performing communication with the individual battery modules. Here, a dummy module has an adjacent identifier to an identifier of the most downstream battery module to which a power connection system is connected in series, among the plurality of battery modules, and can perform communication with the battery management unit.

Description

  Embodiments described herein relate generally to a secondary battery device and a module connection determination method.

  In a system using a secondary battery device, a plurality of battery modules (also referred to simply as modules) containing a plurality of secondary batteries are connected in parallel, used in series, or used in parallel. Used in combination with a series connection.

  One battery module has a housing having a certain size and a plurality of (for example, two) rooms in parallel in which a plurality of secondary batteries can be accommodated in series. When a plurality of batteries are accommodated in each room, for example, the batteries are connected in series.

  In the battery module, a cell control unit (also referred to as a cell monitoring unit (CMU)) capable of mutual communication with an external battery management unit (BMU) is provided.

  The cell control unit includes a voltage detector that detects the battery voltage, a temperature detector that detects the temperature, a current detector that detects the current of the battery module, a cell equalization circuit for equalizing the cell voltage, and a remaining battery capacity. (SOC) It has a calculation part, an open circuit voltage (COV) measurement part etc. which measure the battery voltage before and behind charging / discharging. Furthermore, a communication controller for transmitting measured battery voltage information and SOC information to an external battery management unit (BMU) and receiving an operation command from the outside is included.

  The battery management unit (BMU) can receive information from a plurality of battery modules and give instructions to each battery module. For example, transmission of information, implementation / stop of charge / discharge, and the like. For example, a control area network (CAN) is used for this communication standard.

JP 2008-193757 A

  As described above, when the battery management unit manages a plurality of battery modules, it is necessary to recognize that each battery module is connected. For this reason, as a recognition method, module IDs are assigned to a plurality of battery modules, and mutual communication is performed using the module IDs.

  However, the battery management unit cannot grasp how many of the plurality of modules are connected in parallel and how many are connected in series only by the module ID information. However, in order to calculate the remaining battery capacity (SOC) in order to protect the module from overvoltage and overcurrent, it is necessary to know how many battery modules are connected in parallel and how many are connected in series. There is a need to. This is because battery modules connected in series need to monitor overvoltage and overcurrent independently for each battery module, and in order to calculate the remaining battery capacity, measure the battery voltage individually for each battery module. Because it is necessary to do.

  Therefore, information on how many of the plurality of battery modules are connected in parallel and how many are connected in series is stored in advance in a memory in the battery management unit as a parameter. That is, the module IDs connected in parallel and the module IDs connected in series are described in the table.

  However, when the battery module is replaced, or when the system is changed and the number of modules connected in series or parallel changes, parameters are created and input to the battery management unit each time. There is a need. Such an input process has the possibility of causing an erroneous input, and the operation becomes complicated.

  Therefore, an object of the present embodiment is to provide a secondary battery device and a module connection determination method in which the battery management unit can automatically detect the parallel connection and series connection state of the battery modules.

  According to the embodiment, a plurality of battery modules, a battery management unit that determines individual battery modules with identifiers assigned to the plurality of battery modules and communicates with the individual battery modules via a communication system or the like. A dummy module arranged subsequent to the last battery module connected in series on the communication system in order to notify the battery management unit of a break in the serial connection state of the plurality of battery modules.

It is a structure explanatory view which is an example of embodiment and shows a communication system. It is a composition explanatory view showing an electric power connection system which is an example of an embodiment. It is a block diagram which shows an example of the component inside a battery module. It is explanatory drawing which shows an example of the data transmission frame utilized with a communication system in one Embodiment. It is explanatory drawing which shows the example of the identifier in a some battery module in one Embodiment. It is explanatory drawing which shows the example of the data transmission frame and dummy data of a dummy module in one Embodiment. It is explanatory drawing which shows an example of the battery voltage data and dummy data transmitted from the some battery module of FIG. 1A. It is a figure which shows the example of the connection form of the some battery module in other embodiment. It is a figure which shows the example of the connection form of the some battery module in other embodiment. It is a flowchart which shows an example of the module connection form determination processing operation in a battery management unit.

  Hereinafter, embodiments will be described with reference to the drawings. First, FIG. 1A shows a communication path 400 of the embodiment, and FIG. 1B shows a power system 410.

  FIG. 1A shows battery modules 1, 2, 3, 4, 5, and 6 stored in the storage box 100. Here, a plurality of secondary batteries (hereinafter abbreviated as cells) are accommodated in the battery modules 1, 2, 4, and 5. In order for the battery management unit (BMU) 300 to recognize the connection form of the battery modules, the dummy modules 3 and 6 are arranged.

  The battery module 1 will be described as a representative. The battery module 1 includes, for example, a case 111 having a certain size and a plurality of (for example, two) rooms in parallel in which a plurality of cells C1 to C12 can be accommodated in series.

  When a plurality of cells C1-C12 are accommodated in each room, for example, the cells C1-C12 are connected in series. This example is an example, and there are various types of battery modules, and the cell connection mode and the number of cells stored may be adjusted according to the requirements (capacity, output voltage, etc.) of the system used.

  Further, in the battery module 11, a cell control unit (also referred to as a cell monitoring unit (CMU)) 120 capable of mutual communication with an external battery management unit (BMU) 300 is provided.

  Although the configuration of the battery module 1 is shown, the other battery modules 2, 4, and 5 have the same configuration. Furthermore, in this apparatus, dummy modules 3 and 6 are provided. The dummy modules 3 and 6 are used for the battery management unit 300 to determine the connection form of the power system of the battery modules 1, 2, 4, and 5. FIG. 1A shows a communication path 400 through which the battery management unit (BMU) 300 and the cell control unit in each module 1-6 communicate with each other.

  FIG. 1B shows a power connection system 410 of the battery modules 11-14. The battery management unit 300 includes a processor that collects data from each module and sends commands to each battery module. Moreover, the terminal board for charging / discharging each battery module shall also be included. In addition, the charge / discharge system (electric power system) to each battery module may be separately provided.

  In this example, the battery modules 1 and 2 are connected in series, the battery modules 4 and 5 are connected in series, and the series circuit of the battery modules 1 and 2 and the series circuit of the battery modules 4 and 5 are connected in parallel. Whether the battery modules are connected in series or in parallel can be arbitrarily selected by selecting or switching a terminal and a switch attached to the housing 100 or performing wiring.

  Here, the dummy modules 3 and 6 are respectively arranged subsequent to the end of series connection of a plurality of battery modules. Alternatively, the dummy modules 3 and 6 are each arranged immediately downstream of the series connection of a plurality of battery modules. That is, a dummy module is used to identify the end of series connection of battery modules.

  A method for determining the presence of the dummy joule will be described later. This dummy module does not have a real cell, and has dummy data as battery data in a memory provided on the substrate, and the size is extremely small compared to the battery module. Therefore, the dummy module can be manufactured at low cost. In FIG. 1B, for ease of understanding, the size is the same as that of the battery module, but the size of the dummy module may be small.

  As shown in FIGS. 1A and 1B, the dummy modules 3 and 6 are connected to the battery management unit (BMU) in the communication system, but are not connected in the power connection system.

  FIG. 2 is a block diagram illustrating an example of components inside the battery module 1. The plus side of the cells C1-C12 connected in series is connected to the terminal board in the battery management unit 200 as a power connection system via the plus terminal 101. This plus terminal can be connected to a plus terminal of a load (not shown), for example. Further, when a regenerative current flows from the load, it can serve as a charging side terminal.

  The minus side of the series-connected cells C1 to C12 is connected to the minus terminal 102 via the current detector 134. The negative terminal 102 is connected to a negative terminal (also referred to as ground) of the load.

  The voltage detector 131 can be connected to the terminals of the cells C1 to C12 through a switch. Based on the control of a timing control circuit (not shown), the voltage detector 131 measures the voltage of each cell. Further, the temperature detector 132 measures the temperature of a part or the whole of the cells C1 to C12. The measured cell voltage and temperature are collected by the microprocessor (MPU) 135, and the remaining battery capacity (SOC) is estimated, whether or not the voltage equalization process between cells is necessary, and the like are determined.

  The microprocessor 135 can transmit the collected cell voltage to the battery management unit 300 via the communication controller 136 together with a module identifier (module ID). For example, a control area network (CAN) is used as a general method used in this case. The microprocessor 135 can also transmit the remaining battery capacity (SOC) to the battery management unit 300 via the communication controller 136.

  The battery management unit 300 can transmit a charge / discharge control command and / or an equalization processing command to the battery module 111 based on information such as cell voltage and SOC. The battery management unit 300 can receive cell voltage data, SOC, and the like from other modules, and can control the operation state of the entire system.

  2, the battery module 1 is shown as a representative, but the other battery modules 2, 3,... Are also connected to the battery management unit 300 through a communication system.

  FIG. 3 shows an example of a format when, for example, cell voltage measurement data of the battery module 1 is transmitted to the BMU 300. In this communication standard, one frame is composed of, for example, a CANID and an 8-byte data area. Therefore, if 2 bytes are used to express the cell voltage of one cell, 24 bytes are required to transmit the measurement data of 12 cells. Therefore, since one frame is 8 bytes, three frames (first, second, and third frames) with each frame CANID are required to transmit measurement data of 12 cells.

  Cell voltage 1-cell voltage 4 is assigned to the first frame, cell voltage 5-cell voltage 8 is assigned to the second frame, and cell voltage 9-cell voltage 12 is assigned to the third frame.

  The cell voltage takes a value of around 0 to 3 V, and can be expressed in hexadecimal by 0x0000 (0000 mV) to 0x0BB8 (3000 mV), and requires 2 bytes of information. Therefore, 2 bytes are allocated as a voltage region in one cell as described above.

  FIG. 4 shows an example of the total number of frames (12 frames) necessary for transmitting the cell voltage data of the four battery modules 1, 2, 4, 5 shown in FIG. 1A to the BMU 300. Each frame is identified by a CANID assigned to each module. On the other hand, the dummy module information is as follows.

  FIG. 5 shows an example of the cell voltage in each frame of the dummy modules 3 and 6. The frame structure for the dummy modules 3 and 6 is the same as the frame structure for the other battery modules. However, the cell voltage data for the dummy modules 3 and 6 is set to a value that a real cell can never take, that is, a value that can reliably identify a dummy module. For example, if it is 0xCCCC (52428 mV), a real cell is a value that cannot be taken.

  If the cell monitoring unit (CMU) cannot acquire cell voltage information and the numerical value indicating the presence of an abnormality is set using a value that cannot be taken by a real cell, the dummy module It is preferable that the numerical value indicating that the value is different from the numerical value indicating that the abnormality exists. This makes it possible to distinguish and detect “the presence of a dummy module” and “when there is an abnormality”.

  FIG. 6 shows an example in which a battery management unit (BMU) 300 receives cell voltage data from each module and creates a table in the module arrangement shown in FIG. 1A.

  First, after replacement or inspection of a module is performed, or in an inspection operation at the time of factory shipment, the battery management unit (BMU) 300 checks the connection state of the module.

  When the battery management unit (BMU) 300 collects cell voltage data from each module, the battery management unit (BMU) 300 assigns CANIDs (module IDs) for three frames in order to each module. Next, the MPU of each module is instructed to collect cell voltages and transmit cell voltage data.

  This allows the battery management unit (BMU) 300 to receive at least 18 frames and build a table of all cell voltage data for each module 1-6.

  As can be seen from this table, the battery management unit (BMU) 300 can immediately determine that the third and sixth modules are dummy modules.

  Here, modules 1 and 2 are connected in series, modules 4 and 5 are connected in series, a series circuit of modules 1 and 2 and a series circuit of modules 4 and 5 are connected in parallel. Judging. In this system, when the cell voltage data indicates a notification value excluding the cell voltage range (a value such as 0xCCCC (52428 mV) described above), the battery module that transmitted the notification value is determined as a dummy module, This is because it is determined that the module identifier is an identifier indicating the end of series connection of a plurality of battery modules.

  FIG. 7 shows another embodiment. In this example, the battery modules 1, 3, and 5 are parallel when viewed in the power connection system 410. The dummy modules 2, 4, 6 are arranged following the respective battery modules 1, 3, 5 (downstream of the respective battery modules 1, 3, 5).

  The BMU 300 uses the communication system 400 to sequentially assign IDs to the modules 1-6 (from upstream to downstream). Next, each module is instructed to transmit voltage data based on the CAN format. The BMU 300 constructs a voltage data table for each module. Thereby, it is determined that the module having the voltage data outside the regulation is a dummy module. In the example of FIG. 7, it is determined that the modules 2, 4, and 6 are dummy modules. As a result, the BMU 300 determines that the one upstream module of the dummy module is the last battery module connected in series with respect to the power connection system.

  FIG. 8 shows still another embodiment. In this example, the battery modules 1, 2, and 3 are in series when viewed from the power connection system 410. The dummy module 4 is arranged following the battery module 3 (downstream of each battery module 3).

  The BMU 300 uses the communication system 400 to sequentially assign IDs to the modules 1-4 (from upstream to downstream). Next, each module is instructed to transmit voltage data based on the CAN format. The BMU 300 constructs a voltage data table for each module. Thereby, it is determined that the module having the voltage data outside the regulation is a dummy module. In the example of FIG. 8, it is determined that the module 4 is a dummy module. As a result, the BMU 300 determines that the modules 1, 2, and 3 upstream from the dummy module are battery modules connected in series with respect to the power connection system.

  FIG. 9 is a flowchart showing an operation example in the battery management unit (BMU). The battery management unit (BMU) 300 checks the module connection state after module replacement, inspection, etc., or in inspection work at the time of factory shipment. This operation may be operated by a user from the outside, or may be automatically activated based on software.

  The battery management unit (BMU) 300 assigns IDs in order from the upstream to each module of the communication system (step SA1). In response to the ID assignment, after receiving a response from each module, the module is requested to transmit voltage data.

  The battery management unit (BMU) 300 sequentially stores the received data in a table. In addition, the battery management unit (BMU) 300 detects the voltage data of each frame that has been sent, and determines whether the data has the notification value from the dummy module.

  If the data has a notification value from the dummy module (steps SA3 and SA4), a break is recorded in the connection form image table (step SA5).

  When the voltage data from all modules is acquired (step SA6), a table as shown in FIG. 6 is constructed. Based on this table, the module connection form is determined (step SA7), and the process is terminated.

  As described above, a plurality of battery modules and a battery management unit that determines individual battery modules with identifiers assigned to the plurality of battery modules and communicates with the individual battery modules via a communication system or the like. It is a system that has. The dummy module is arranged following the last battery module connected in series on the communication system in order to notify the battery management unit of a break in the serial connection state of the plurality of battery modules.

  In the above description, the number of modules has been described as a small number in order to make the description easy to understand. However, in actuality, a larger number of modules are used according to the requirements of the system. According to the embodiment, the battery module and the dummy module are arranged with regularity. Therefore, if there is an error in the connection location of the dummy module or a connection error between the parallel connection and the series connection of the battery modules, this regularity cannot be established. Therefore, it is possible to detect a wiring error or a connection error by providing a program for determining the regularity of connection in the BMU.

  Various secondary batteries such as a lithium ion battery and a nickel metal hydride battery have been developed as secondary batteries to which the present embodiment is applied, and any battery can be used. In addition, in the case of a characteristic in which the change in the OCV follows the change in the SOC, the SOC can be estimated from the OCV with relatively high accuracy.

  Examples of materials such as the negative electrode, the positive electrode, and the electrolyte of the secondary battery are shown below.

1) Negative electrode: The negative electrode has a negative electrode current collector and a negative electrode active material-containing layer. The negative electrode active material-containing layer includes a negative electrode active material, a conductive agent, and a binder. A metal foil such as an aluminum alloy foil can be used for the negative electrode current collector. Examples of the aluminum alloy include, in addition to aluminum, an Al—Fe alloy, an Al—Mn alloy, and an Al—Mg alloy.

  As the negative electrode active material, a material that occludes and releases lithium can be used. Among them, metal oxides, metal sulfides, metal nitrides, alloys, and the like can be given. The lithium occlusion potential of the negative electrode active material is preferably 0.4 V or more in terms of open circuit potential relative to the open circuit potential of lithium metal. Thereby, the progress of the alloying reaction between the aluminum component of the negative electrode current collector and lithium and the pulverization of the negative electrode current collector can be suppressed. Furthermore, the lithium occlusion potential is preferably in the range of 0.4 V or more and 3 V or less in terms of open circuit potential with respect to the open circuit potential of lithium metal. Thereby, a battery voltage can be improved. A more preferable potential range is 0.4 V or more and 2 V or less. Examples of the metal oxide capable of occluding lithium in the range of 0.4 V or more and 3 V or less include titanium oxide, such as lithium titanium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, and silicon oxide. Etc. Among these, lithium titanium oxide is preferable.

  Examples of the metal sulfide that can occlude lithium in the range of 0.4 V or more and 3 V or less include lithium sulfide, molybdenum sulfide, iron sulfide, and the like.

  Examples of the metal nitride capable of occluding lithium in the range of 0.4 V or more and 3 V or less include lithium cobalt nitride.

  A carbon material can be used as the conductive agent. Examples thereof include acetylene black, carbon black, coke, carbon fiber, and graphite.

  2) Positive electrode: The positive electrode has a positive electrode current collector and a positive electrode active material-containing layer. The positive electrode active material-containing layer is supported on one surface or both surfaces of the positive electrode current collector 19a and includes a positive electrode active material, a conductive agent, and a binder.

  A metal foil such as an aluminum alloy foil can be used for the positive electrode current collector. Examples of the positive electrode active material include oxides, sulfides, and polymers.

Examples of the oxide include manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium manganese cobalt. Examples include composite oxides, spinel-type lithium manganese nickel composite oxides, lithium phosphorus oxides having an olipine structure, iron sulfate, and vanadium oxides.

  Examples of the polymer include conductive polymer materials such as polyaniline and polypyrrole, and disulfide polymer materials. In addition, sulfur (S), carbon fluoride, and the like can be used.

  As a preferable positive electrode active material, since a high positive electrode voltage can be obtained, lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, spinel type lithium manganese nickel composite oxide, lithium Examples thereof include manganese cobalt composite oxide and lithium iron phosphate.

  Examples of the conductive agent for increasing the electron conductivity and suppressing the contact resistance with the current collector include acetylene black, carbon black, and graphite.

  3) Electrolytic solution: The electrolytic solution is prepared by dissolving an electrolyte in an organic solvent. The electrolyte concentration can be in the range of 0.5 to 2 mol / L.

Examples of the electrolyte include LiBF ₄ . Examples of the organic solvent include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC), chains such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), and diethyl carbonate (DEC). Carbonates, cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), chain ethers such as dimethoxyethane (DME), γ-butyrolactone (BL), acetonitrile (AN), sulfolane (SL), phosphate esters Etc. These organic solvents can be used alone or in the form of a mixture of two or more.

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof. Further, terms used in the present specification are not limited, and equivalent terms are within the scope of the present invention.

1-6 ... Battery (or dummy) module, C1-C12 ... Cell, 20 ... Cell control unit, 100 ... Storage box, 300 ... Battery management unit (BMU).

Claims (5)

A plurality of battery modules;
A battery management unit that determines individual battery modules and communicates with the individual battery modules via a communication system or the like with identifiers assigned to the plurality of battery modules;
A secondary battery having a dummy module arranged following the last battery module connected in series on the communication system in order to notify the battery management unit of a break in the serial connection state of the plurality of battery modules. apparatus. The dummy module is
Among the plurality of battery modules, a power connection system is connected in series and has an identifier next to the identifier of the battery module that is the most downstream, and communicates with the battery management unit.
The secondary battery device according to claim 1.   The secondary battery device according to claim 1, wherein the dummy module has dummy data in a memory provided on a substrate. A module connection determination method for a battery management unit that communicates via a communication system with a plurality of modules each having an identifier,
Receiving each identifier from the plurality of modules and voltage data of the cells in the module by a predetermined communication method,
When the voltage data indicates a notification value excluding a cell voltage range, the module that transmitted the notification value is determined as a dummy module;
The identifier module immediately upstream of the dummy module identifier is determined to be a battery module in series with the power connection system.
Secondary battery module connection determination method.   5. The secondary battery module connection determination according to claim 4, wherein the battery voltage data is received, the determination of the dummy module, and the determination of the serial battery module is performed after a maintenance inspection operation or after assembly of the secondary battery device. Method.

Images