Battery management device and battery management method

Abstract

To provide a storage battery management device that measures the voltage of each battery cell that makes up the battery module without being affected by the contact resistance even during a period in which contact resistance exists between connection paths that connect each battery modules in a storage battery, and current flows at the time of charging and discharging.SOLUTION: A storage battery management device according to the present invention is a device that manages the voltage of each battery cell in a battery module, and includes a battery cell voltage measurement circuit that measures a voltage difference between the measurement terminals to which the positive and negative terminals of the battery cell are connected independently. In series-connected battery cells, the negative terminal of the battery cell on the high voltage side and the positive terminal on the low voltage side are used as one measurement point, and the negative terminal of the battery cell connected to the negative side connection terminal of the battery module connected in series and the positive terminal of the battery cell connected to the positive side connection terminal of the battery module are used as one measuring point. The battery cell voltage measurement circuit measures the potential difference between the measurement points as a cell voltage.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a storage battery management device and a storage battery management method. [Background technology]

[0002] In recent years, in order to conserve energy, storage batteries have been put into operation that improve the efficiency of electrical energy utilization by temporarily storing electricity generated from renewable energy sources, such as electricity generated by solar cells (so-called solar panels), in storage batteries and using it as needed. Furthermore, some battery cells constituting a battery module used in a storage battery, such as lithium ion batteries, require strict voltage management because the voltage values ​​of the normal use region and the prohibited use region are close to each other. Therefore, in order to manage the voltage of the battery cells, the voltage (cell voltage) of each of the battery cells in each of the multiple battery modules that make up the storage battery is measured, and cell balancing is performed on each battery cell (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-68533 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, as shown in FIG. 9, in a storage battery, a contact resistance (or connection resistance) R occurs in a connection path CP between the negative side connection terminal 201(-) of the high-voltage side battery module 201 and the positive side connection terminal 202(+) of the low-voltage side battery module 202, which are connected in series. That is, in this connection path CP, the contact resistance R is formed as the sum of the contact resistances of the contact surfaces at the connection point between connector 211 and connector 621, the connection point between connector 611 and connector 111, the connection point between connector 112 and connector 612, and the connection point between connector 622 and connector 212 (Figure 6 described later).

[0005] Here, when neither discharging nor charging is being performed in each of the battery modules 201 and 202, no current flows through the contact resistance R, and therefore no potential is generated across the contact resistance R in the connection path CP. On the other hand, when charging or discharging is being performed on each of the battery modules 201 and 202, a current I flows through the contact resistance R as a charging current or a discharging current. As a result, a potential V corresponding to the resistance value of the contact resistance R and the current value of the current I is generated across both ends of the contact resistance R, i.e., between the negative side connection terminal 201(-) and the positive side connection terminal 202(+). Therefore, the negative connection terminal 201(-) of the battery module 201 and the positive connection terminal 202(+) of the battery module 202 are no longer at the same potential.

[0006] In addition, the negative terminal of the battery cell 201_n of the battery module 201 and the positive terminal of the battery module 202, i.e., the negative side connection terminal 201(-) and the positive side connection terminal 202(+), are connected to the same measurement terminal P1z in the battery cell voltage measurement circuit 301. Each of the measurement terminals shown in FIG. 9 is used to connect the connection points of the - terminals and + terminals of each of the battery cells connected in series to the measurement terminals of the battery cell voltage measurement circuit 301 as shown below, and to measure the voltage between the measurement terminals as the cell voltage.

[0007] Here, in the connection path CP, the voltages at the negative connection terminal 201(-) of the battery module 201 and the positive connection terminal 202(+) of the battery module 202 are not the same due to the voltage drop caused by the contact resistance described above. A path resistance R1 due to contact resistance and wiring resistance in the connection terminal 302 exists between the negative connection terminal 201(-) of the battery module 201 (i.e., the negative terminal of the battery cell 201_n) and the measurement terminal QP1n(-) of the battery cell voltage measurement circuit 301. Similarly, a path resistance R2 due to contact resistance and wiring resistance at the connection terminal 303 exists between the + side connection terminal 202(+) of the battery module 202 (i.e., the + terminal of the battery cell 202_1) and the measurement terminal QP21(+) of the battery cell voltage measurement circuit 301.

[0008] Therefore, the voltage V generated across the resistor R is divided by the path resistors R1 and R2, and voltages V1 and V2 are generated across the path resistors R1 and R2, respectively. Then, voltages V1 and V2 are applied to the measured voltage VS1_n of battery cell 201_n, whose - terminal is connected to the - side connection terminal 201(-) of battery module 201, and to the measured voltage VS2_1 of battery cell 202_1, whose + terminal is connected to the + side connection terminal 202(+) of battery module 202, respectively. As a result, when charging or discharging is occurring and a current is flowing through the contact resistance, the measurement voltage VS1_n measured by the battery cell voltage measurement circuit 301 includes the voltage V1, and the measurement voltage VS2_1 includes the voltage V2.

[0009] Therefore, when charging or discharging is taking place, it is not possible to accurately measure the voltage of the battery cell 201_n connected to the negative connection terminal of the high-voltage battery module 201 connected in series, or the voltage of the battery cell 202_1 connected to the positive connection terminal 202(+) of the low-voltage battery module 202. For this reason, when performing cell balancing of the cell voltages in each of the battery modules 201 and 202, the measured cell voltages of the battery cell 201_n and the battery cell 202_1 each contain voltages V1 and V2 as errors, making it impossible to perform strict voltage management of each battery cell, such as cell balancing.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide a battery management device and a battery management method that can measure the voltage of each battery cell that constitutes a battery module without being affected by contact resistance, even when contact resistance exists between the connection paths that connect each of the battery modules in a storage battery and current flows during charging and discharging. [Means for solving the problem]

[0011] One aspect of the battery management device of the present invention is a storage battery Multiple connected in series A storage battery management device that manages the voltage of each of the battery cells in a battery module, the storage battery management device comprising: a battery cell voltage measurement circuit that measures the cell voltage of each of the battery cells, the battery cell voltage measurement circuit having measurement terminals to which the + terminal and - terminal of each of the battery cells are independently connected, and the battery cell voltage measurement circuit measures the voltage difference between the measurement terminals as the cell voltage; Multiple Battery Module For each of the following: In each of the series-connected battery cells, the negative terminal of the high-voltage battery cell and Adjacent to the battery cell Low voltage side Battery cell + terminal is one measurement point, while The Battery Module of- a negative terminal of a battery cell connected to the negative connection terminal; The Each of the positive terminals of the battery cells connected to the positive connection terminal of the battery module is considered as a measurement point. death, The battery cell voltage measurement circuit A negative terminal of a battery cell connected to a negative connection terminal of each of the plurality of battery modules and a positive terminal of a battery cell connected to a positive connection terminal of another battery module connected to the negative connection terminal of the battery module are set as independent measurement points, and a potential difference between the independent measurement points is excluded from the measurement target as the cell voltage, and a potential difference corresponding to the positive terminal and the negative terminal of each of the battery cells in the plurality of battery modules connected in series is set as a potential difference between the independent measurement points. The potential difference between the measurement points is measured as the cell voltage.

[0012] One aspect of the storage battery management method of the present invention is to configure a storage battery Multiple connected in series A storage battery management method for managing the voltage of each of the battery cells in a battery module, the method comprising: a battery cell voltage measurement circuit for measuring the cell voltage of each of the battery cells, the battery cell voltage measurement circuit having measurement terminals to which the + terminal and - terminal of each of the battery cells are independently connected, and the voltage difference between the measurement terminals is measured as the cell voltage; Multiple Battery Module For each of the following:In each of the series-connected battery cells, the negative terminal of the high-voltage battery cell and Adjacent to the battery cell Low voltage side Battery cell + terminal is one measurement point, while The Battery Module of- a negative terminal of a battery cell connected to the negative connection terminal; The Each of the positive terminals of the battery cells connected to the positive connection terminal of the battery module is considered as a measurement point. death, The battery cell voltage measurement circuit A negative terminal of a battery cell connected to a negative connection terminal of each of the plurality of battery modules and a positive terminal of a battery cell connected to a positive connection terminal of another battery module connected to the negative connection terminal of the battery module are set as independent measurement points, and a potential difference between the independent measurement points is excluded from the measurement target as the cell voltage, and a potential difference corresponding to the positive terminal and the negative terminal of each of the battery cells in the plurality of battery modules connected in series is set as a potential difference between the independent measurement points. The potential difference between the measurement points is measured as the cell voltage. Effect of the Invention

[0013] According to the present invention, it is possible to provide a battery management device and a battery management method that can measure the voltage of each of the battery cells that make up a battery module without being affected by contact resistance, even during periods when current flows during charging and discharging, when contact resistance exists between the connection paths that connect each of the battery modules in a storage battery. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram showing an overview of a power supply system according to the present invention; [Diagram 2] FIG. 1 is an explanatory diagram illustrating an overview of a storage battery unit used in a power supply system according to the present invention. [Diagram 3] 1 is an explanatory diagram illustrating an overview of a relay cable that connects a connector of a battery module and a connector of a control management module. [Figure 4] 1 is an explanatory diagram illustrating an overview of a relay cable that connects a connector of a battery module and a connector of a control management module. [Diagram 5] FIG. 2 is an explanatory diagram of an example of a battery module. [Figure 6] FIG. 2 is a block diagram showing a configuration of a control management module. [Figure 7] FIG. 2 is a block diagram showing an overview of an AFE circuit element disposed on a BMS substrate. [Figure 8]1 is a block diagram showing an example of a schematic configuration of a battery management device that manages battery cells in a battery module according to an embodiment of the present invention. [Figure 9] 1 is a block diagram showing an example of a schematic configuration of a battery management device that manages battery cells in a general battery module. [Figure 10] FIG. 13 is a block diagram showing an outline of another configuration example of a power supply system according to the present invention. [Figure 11] FIG. 13 is a block diagram showing an outline of another configuration example of a power supply system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. <Overall system> Fig. 1 is a block diagram showing an overview of a power supply system 10 according to the present invention. As shown in Fig. 1, the power supply system 10 according to the embodiment of the present invention includes a power conditioner 1, a solar panel 2, and a power storage unit 3.

[0016] The power conditioner 1 performs processes such as conversion between DC and AC power, control of power supply voltage, and buying and selling electricity. That is, while commercial power supply 5 uses AC power, solar power generation and electricity storage use DC power. Also, the voltage of commercial power supply 5 differs from the voltage of the batteries used in solar panel 2 and storage battery unit 3. The power conditioner 1 converts between DC and AC power and controls the power supply voltage between the commercial power supply 5, solar panel 2, and storage battery unit 3. The power conditioner 1 then supplies power to a distribution board 6, which distributes the power to the outlets in each room.

[0017] The solar panel 2 can generate electricity during the daytime when the sun is out, but cannot generate electricity at night when the sun sets, and the amount of electricity generated is unstable. The storage battery unit 3 can be charged from the grid via the commercial power source 5 and power conditioner 1 during the day, and can also be charged via the solar panel 2 and power conditioner 1, and can also supplement the power supply via the power conditioner 1. The storage battery unit 3 can be charged from the grid via the commercial power source 5 and power conditioner 1 at night, and can also supplement the power supply via the power conditioner 1.

[0018] In addition, the power conditioner 1 performs processes such as purchasing and selling power, such as purchasing power from a commercial power source 5 when there is a power shortage, and selling power to the commercial power source 5 when there is surplus power from the solar panel 2.

[0019] An EV (Electric Vehicle) stand 4 can also be incorporated into the power supply system 10. The EV stand 4 can be used to charge an electric vehicle, as well as to store power using a battery installed in the electric vehicle. The EV stand 4 can also supplement the power supply via the power conditioner 1.

[0020] Fig. 2 is an explanatory diagram of an overview of the storage battery unit 3 used in the power supply system 10 according to the present invention. As shown in Fig. 2, the storage battery unit 3 is composed of, for example, seven battery modules 201-207 and a control management module 100 (sometimes referred to as a storage battery management device 100). In this embodiment, a configuration including seven battery modules will be described as an example, but any number of battery modules may be used as long as it is two or more. A battery stack made up of a plurality of battery cells is provided in the battery modules 201 to 207. In addition, the battery modules 201 to 202 are provided with connectors 211 to 217 and connectors 221 to 222, respectively.

[0021] The control management module 100 manages the charge / discharge states and the discharge states of the battery modules 201-207. The control management module 100 is provided with connectors 111-117 and connectors 121-127. The connectors 211-217 of the battery modules 201-207 and the connectors 111-117 of the control management module 100 are connected by relay cables 60-1-60-7 as shown in Fig. 3. The connectors 221-227 of the battery modules 201-207 and the connectors 121-127 of the control management module 100 are connected by relay cables 70-1-70-7 as shown in Fig. 4.

[0022] FIG. 3 is an explanatory diagram showing an outline of the relay cables 60 (601 to 607) that connect the connectors 211 to 217 of the battery modules 201 to 207 and the connectors 111 to 117 of the control management module 100. As shown in FIG.

[0023] 3, the relay cable 60 is made up of connectors 61 (611-617) on the battery modules 201-207 side, connectors 62 (621-627) on the control management module 100 side, and cables 63 (631-63n) therebetween. The cables 63 (631-637) are two wires: a positive wiring (+ side wiring) and a negative wiring (- side wiring).

[0024] FIG. 4 is an explanatory diagram illustrating an outline of the relay cables 70 (70-1 to 70-7) that connect the connectors 221 to 227 of the battery modules 201 to 207 and the connectors 121 to 127 of the control management module 100. As shown in FIG.

[0025] 4, the relay cable 70 (701-707) is made up of connectors 71 (711-717) on the battery modules 201-207 side, connectors 72 (721-727) on the control management module 10 side, and cables 73 (731-737) therebetween. The cables 73 (731-737) are made up of wiring whose number corresponds to the number of battery cells that make up the battery stack.

[0026] 5 is a diagram showing an example of the configuration of the battery modules 20 (201 to 207). Note that the battery modules 201 to 207 all have the same configuration. As shown in FIG. 5, the battery module 20 (201 to 207) is provided with a battery stack made up of battery cells 20_1 (201_1, 202_1), 20_2 (202_1, 202_2), ..., 20_n (201_1, 201_n) connected in series.

[0027] Lithium ion batteries, for example, lithium iron phosphate ion batteries, are used as the battery cells 20_1, 20_2, ..., 20_n. Lithium iron phosphate ion batteries use lithium iron phosphate in the positive electrode (positive terminal side) and are characterized by their high safety as their crystal structure is not easily destroyed even when heat is generated inside the battery. The cell voltage of each battery cell 20_1, 20_2, ..., 20_n differs depending on the cell structure. In the case of a lithium ion battery, the cell voltage is 2V to 4V. In the case of a lithium iron phosphate ion battery, the cell voltage is, for example, about 3.3V.

[0028] The battery modules 20 (201 to 207) are provided with connectors 21 (211 to 217) and connectors 22 (221 to 227). The connectors 21 (211 to 217) are connectors for charging and discharging each of the battery modules 20 (201 to 207). The connectors 22 (221 to 227) are connectors for monitoring the cell voltages of the battery cells 20_1, 20_2, ..., 20_n.

[0029] Fig. 6 is a block diagram showing the configuration of the control management module 100. As shown in Fig. 6, the control management module 100 is equipped with a terminal block 31, a breaker 33, an HV (High-Voltage) board 40, and a BMS (Battery Management System) board 50.

[0030] The terminal block 31 is a connector for connecting wiring from the power conditioner 1. The terminal block 31 is provided with a positive (+) terminal 31a, a negative (-) terminal 31b, and a ground terminal 31c. In this example, the ground terminal 31c is connected to the housing as a ground potential. Wires extending from the positive terminal 31a and the negative terminal 31b of the terminal block 31 form charge / discharge lines 35a and 35b. The breaker 33 is for protection when a large current flows.

[0031] The communication connector 32 is a connector for connecting a shielded wire for communication from the power conditioner 1. The communication connector 32 is connected to a communication connector 51 on the BMS board 50. Data from the power conditioner 1 is received via the communication connector 32 and sent to the microprocessor 54. In addition, data from the microprocessor 54 is sent to the power conditioner 1 via the communication connector 32.

[0032] The HV board 40 is a board for charging and discharging the battery modules 201 to 207. On the HV board 40, a relay 41, a current sensor 42, a communication connector 43, and connectors 221 to 227 are mounted.

[0033] The relay 41 serves as a switch for starting / stopping the operation of the power storage unit 3. The current sensor 42 detects charging / discharging current to / from the battery modules 201-207. The communication connector 43 is connected to the communication connector 52 on the BMS board 50. The communication connector 43 transmits the detected current of the current sensor 42 to the microprocessor 54, for example.

[0034] The connectors 111-117 are terminals that connect to the connectors 211-217 on the battery modules 201-207 side, respectively. The connectors 211-217 on the battery modules 201-207 side are connectors for charging and discharging. Wiring from both ends of the battery cells 20_1, 20_2, ..., 20_n that constitute the battery stack is led out from the connectors 111-117. The + terminal of the connector 111 having the highest potential is connected to the charge / discharge line 35a, and the - terminal of the connector 117 having the lowest potential is connected to the charge / discharge line 35b.

[0035] Here, the battery cell 20_1 indicates each of the battery cells 201_ to 207_1 in each of the battery modules 201 to 207. The other battery cells 20_2, ..., 20_n also indicate each of the battery cells in the battery modules 201 to 207, similar to the above-mentioned battery cell 20_1. The connectors 111 to 117 are connected in series so as to obtain a desired charge / discharge voltage.

[0036] The BMS board 50 is a board for monitoring and controlling the states of the battery modules 201 to 207. On the BMS board 50, communication connectors 51 and 52, an AFE (Analog Front End) 53, a microprocessor 54, a photocoupler 55, and connectors 121 to 127 are mounted.

[0037] The communication connector 51 is connected to the communication connector 32, and transmits and receives data to and from the power conditioner 1. The communication connector 52 is connected to the communication connector 43, and transmits and receives data to and from the HV board 40.

[0038] The AFE 53 corresponds to a battery cell voltage measuring circuit 101, which will be described later, and detects the cell voltage of each of the battery cells in each of the battery modules 201 to 207, and converts it into digital data.

[0039] The microprocessor 54 performs various controls based on data from the power conditioner 1, data from the HV board 40, data from the AFE 53, and the like.

[0040] The photocoupler 55 is an optical isolation element, and connects between the AFE 53 and the microprocessor 54. Since a high voltage is applied to the AFE 53, the photocoupler 55 provides isolation between the AFE 53 and the microprocessor 54. Instead of the photocoupler 55, an element such as a digital isolator may be used.

[0041] The connectors 121-127 are terminals that connect to the connectors 221-227 on the battery modules 201-207 side, respectively. The connectors 121 (121-127) are connectors for monitoring the cell voltages of the battery cells 20_1, 20_2, ..., 20_n. The connectors 121-127 transmit the cell voltages of the battery modules 201-207 to the BMS board 50 side, respectively.

[0042] Fig. 7 is a block diagram showing an outline of the AFE circuit element 530 arranged on the BMS board 50. In this embodiment, the function of the AFE 53 is realized by arranging the AFE circuit elements 530 as shown in Fig. 7 in the number corresponding to the battery modules 201 to 207. Note that the description here is limited to a part of the function of the AFE circuit element 530 that is necessary for explaining the present invention.

[0043] 7, terminals A1, A2, ..., Am (m is an arbitrary integer) correspond to measurement terminals QP(+) to QP2n(-) in a battery cell voltage measurement circuit 101 described later, and are measurement terminals for detecting the cell voltages of each of the battery cells in the battery stack. When detecting the cell voltage of the battery stack, the battery cells are connected in the order from terminal A1 to terminal Am, from the electrode with the highest potential to the electrode with the lowest potential.

[0044] The resistor Ra and switch circuit Sa between the stages of the terminals A1, A2, ..., Am are used to perform cell balancing to balance the battery cells. That is, when the switch circuit Sa is turned on, both poles of the battery cells are connected via the resistor Ra, and the electrical energy stored in the battery cells is consumed by Joule heat. This causes the energy of the cell with the largest charge to be consumed, making it possible to equalize the charge amount and voltage of each battery cell. Terminals D1 and D2 are terminals for inputting and outputting data. Data is input and output between AFE 53 (corresponding to a battery cell voltage measuring circuit 101 described later) and microprocessor 54 (corresponding to a storage battery control circuit 102 described later) via terminals D1 and D2.

[0045] Fig. 8 is a block diagram showing an example of a schematic configuration of a battery management device that manages battery cells in a battery module according to an embodiment of the present invention. For ease of explanation, Fig. 8 shows only battery modules 201 and 202 in Fig. 6. The battery management device 100 in Fig. 8 is provided on the BMS board 50 in Fig. 6, and includes a battery cell voltage measuring circuit 101 and a battery control circuit 102. Here, the battery cell voltage measuring circuit 101 is a circuit configured using the AFE 53 (a collection of AFE circuit elements 530) in Fig. 6. The battery control circuit 102 is a circuit having a battery control function such as cell balancing processing by the microprocessor 54 in Fig. 6.

[0046] In this embodiment, a configuration will be described in which the voltage (cell voltage) of each of the battery cells of the two battery modules 201 and 202 is measured, and the measured cell voltages are output to the storage battery control circuit 102. However, the number of battery modules is set arbitrarily depending on the characteristics of the storage battery to be configured, and a configuration in which three or more battery modules are provided may be used as shown in FIG.

[0047] The battery cell voltage measuring circuit 101 measures the voltage (cell voltage) of each of the battery cells of the battery modules, for example, the battery modules 201 and 202, that constitute a battery stack as a storage battery. Here, the battery cell voltage measurement circuit 101 measures the potential differences between each of the measurement terminals P11, P12, P13, ..., P1n-1, P1n, P1z, P21, P22, P23, ..., P2n-1, P2n, P2z as cell voltages.

[0048] Therefore, the connection terminals 103 connect the + terminal and - terminal of each of the battery cells of the battery module 201 to the measurement terminals of the battery cell voltage measuring circuit 101 as measurement points. Similarly, the connection terminals 104 connect the + terminal and - terminal of each of the battery cells of the battery module 202 to measurement terminals of the battery cell voltage measurement circuit 101 as measurement points. Furthermore, the negative connection terminal 201(-) of the battery module 201 and the positive connection terminal 202(+) of the battery module 202 are connected via a connection path CP.

[0049] As already explained in the conventional example, in the connection path CP, there is a contact resistance R on each contact surface of the terminals of each connector that connects the negative side connection terminal 201(-) and the positive side connection terminal 202(+). That is, the connection path CP includes each of the connection points of the connectors 211 and 621, the connection point of the connectors 611 and 111, the connection point of the connectors 112 and 612, and the connection point of the connectors 622 and 212 in Fig. 6, and the contact resistance R is the sum of the contact resistances on the contact surfaces of the respective connectors.

[0050] To a measurement terminal P11 in the battery cell voltage measurement circuit 101, a + terminal of a battery cell 201_1 in a battery module 201 is connected. Moreover, the negative terminal of the battery cell 201_1 and the positive terminal of the battery cell 201_2 constituting the battery module 201 are connected to the measurement terminal P12. To the measurement terminal P13, a negative terminal of a battery cell 201_2 constituting the battery module 201 and a positive terminal of a battery cell 202_3 (not shown) are connected.

[0051] The measurement terminal P1n-1 is connected to a connection point between the negative terminal of a battery cell 201_n-2 (not shown) of the battery module 201 and the positive terminal of the battery cell 201_n-1. A connection point between the negative terminal of the battery cell 201_n-1 of the battery module 201 and the positive terminal of the battery cell 201_n is connected to the measurement terminal P1n. The negative terminal of the battery cell 201_n constituting the battery module 201, that is, the negative side connection terminal 201(-) of the battery module 201, is connected to the measurement terminal P1z.

[0052] Moreover, the positive terminal of the battery cell 202_1 constituting the battery module 202, that is, the positive side connection terminal 202(+) of the battery module 202, is connected to the measurement terminal P21. Furthermore, a connection point between the negative terminal of the battery cell 202_1 constituting the battery module 202 and the positive terminal of the battery cell 201_2 is connected to the measurement terminal P22. A negative terminal of a battery cell 202_2 and a positive terminal of a battery cell 202_3 (not shown) constituting the battery module 202 are connected to the measurement terminal P23.

[0053] The measurement terminal P2n-1 is connected to a connection point between a negative terminal of a battery cell 202_n-2 (not shown) constituting the battery module 202 and a positive terminal of the battery cell 202_n-1. A connection point between the negative terminal of the battery cell 202_n-1 constituting the battery module 202 and the positive terminal of the battery cell 202_n is connected to the measurement terminal P2n. The negative terminal of the battery cell 202_n constituting the battery module 202, that is, the negative terminal 202(-) of the battery module 202, is connected to the measurement terminal P2z.

[0054] As a result, the battery cell voltage measuring circuit 101 measures a measurement voltage VS1_1, which is the voltage between the measurement terminal P11 and the measurement terminal P12, as the cell voltage of the battery cell 201_1. Moreover, the battery cell voltage measuring circuit 1 measures a measurement voltage VS1_2, which is the voltage between the measurement terminal P12 and the measurement terminal P13, as the cell voltage of the battery cell 201_2. The battery cell voltage measuring circuit 101 measures a measurement voltage VS1_n-1, which is the voltage between the measurement terminal P1n-1 and the measurement terminal P1n, as the cell voltage of the battery cell 201_n-1. The battery cell voltage measuring circuit 101 measures a measurement voltage VS1_n, which is the voltage between the measurement terminal P1n and the measurement terminal P1z, as the cell voltage of the battery cell 201_n.

[0055] Moreover, the battery cell voltage measuring circuit 101 measures the voltage between the measurement terminal P21 and the measurement terminal P22 as a measured voltage VS2_1 of the battery cell 202_1. Furthermore, the battery cell voltage measuring circuit 101 measures the voltage between the measurement terminal P22 and the measurement terminal P23 as a measured voltage VS2_2 of the battery cell 202_2. The battery cell voltage measuring circuit 101 measures the voltage between the measurement terminal P2n-1 and the measurement terminal P2n as the measured voltage VS2_n-1 of the battery cell 202_n-1. The battery cell voltage measuring circuit 101 measures the voltage between the measurement terminal P2n and the measurement terminal P2z as the measured voltage VS2_n of the battery cell 202_n.

[0056] That is, in this embodiment, when measuring the cell voltage of each battery cell, in each of the battery modules 201 and 202 connected in series, the - side connection terminal 201(-) of the high-voltage side battery module 201 and the + side connection terminal 202 of the low-voltage side battery module 202 are each connected to different measurement terminals P1z, P21 of the battery cell voltage measurement circuit 101, respectively. On the other hand, the - terminal of the battery cell 201_n and the + terminal of the battery cell 202_1 connected in series that constitute each of the battery modules 201 and 202 are each treated as independent measurement points for measuring the cell voltage and are connected to separate measurement terminals.

[0057] As described above, in the battery management device of this embodiment, the battery cell voltage measurement circuit 101 is provided with measurement terminals to which the connection points of the + and - terminals of each battery cell are independently connected in order to measure the cell voltage of each battery cell in each of the battery modules 20 that constitute the storage battery, and the potential difference between the measurement terminals is measured as the cell voltage.

[0058] That is, in the battery cell voltage measurement circuit 101, for each of the battery cells connected in series in the battery module 20, the connection point between the - terminal of the high-voltage battery cell and the + terminal of the low-voltage battery cell is at the same potential and connected to one measurement terminal. However, the battery cell voltage measurement circuit 101 does not connect the - terminal of the battery cell connected to the - side connection terminal of each of the battery modules 20 connected in series and the + terminal of the battery cell connected to the + side connection terminal of the other battery module to a single independent measurement terminal, and does not measure the potential difference between the measurement terminals as the cell voltage.

[0059] That is, the voltage between each of measurement terminals P1z and P21 is the voltage V generated across contact resistance R at the connection point between terminal 201(-) of battery module 201 and terminal 202(+) of battery module 202, depending on each of the current value of current I and the resistance value of contact resistance R. The battery cell voltage measurement circuit 101 does not measure the voltage between the measurement terminals P1z and P21, i.e., the voltage V generated across the contact resistance R, as a blank value in the cell voltages measured in each of the series-connected battery cells. In other words, the battery cell voltage measurement circuit 101 does not use the voltage V generated across the contact resistance R in voltage control during cell balancing of the battery cells in the battery module, and therefore does not measure the voltage between the measurement terminals P1z and P21, or if it does measure it, does not use it.

[0060] As a result, when the battery cells in each of the battery modules 201 and 202 are being charged or discharged, the voltage generated across the contact resistance R at the connection point of the battery modules 201 and 202 is not included in the cell voltages VS1_n and VS2_1 of the battery cells 201_n and 202_1, respectively. As a result, the battery cell voltage measuring circuit 101 can also accurately measure the cell voltage of the battery cell connected to the connection point of the battery modules connected in series.

[0061] Then, the battery cell voltage measuring circuit 101 outputs the measured cell voltages VS1_1, VS1_2, . . . , VS1_n-1, VS1n of the battery cells 201_1, 201_1, . . . , 201_n-1, and 201_n in the storage battery module 201 to the storage battery control circuit 102. In addition, the battery cell voltage measuring circuit 101 outputs cell voltages VS2_1, VS2_2, . . . , VS2_n-1, VS2n, which are the measured cell voltages of the battery cells 202_1, 202_1, . . . , 202_n-1, and 202_n in the storage battery module 202, to the storage battery control circuit 102.

[0062] Due to individual differences in characteristics such as capacity and leakage among the battery cells, imbalances in cell voltages occur during charging and discharging. When the measured cell voltages of each battery cell in the battery module are supplied from the battery cell voltage measurement circuit 101, the storage battery control circuit 102 performs cell balancing processing corresponding to the cell voltage to suppress over-discharging during discharging and over-charging during charging. This allows the storage battery control circuit 102 to perform cell balancing, which performs highly accurate voltage management for each battery cell of the battery modules 201 to 207, both during charging and discharging.

[0063] As described above, according to this embodiment, when measuring the cell voltage of each battery cell in each battery module in a storage battery in which multiple battery modules are connected in series as in the conventional example, unlike the connection points between battery cells within the battery module, each terminal (+ terminal or - terminal) of the battery cell connected to the connection point between the battery modules is connected to one independent measurement terminal, and the potential of the - side connection terminal of the high-voltage battery module and the + side connection terminal of the low-voltage battery module at the connection point are measured separately. This prevents the voltage V generated by the current flowing through the contact resistance R at the connection point during charging and discharging from affecting the cell voltages of the battery cell whose - terminal is connected to the - side connection terminal of the high-voltage battery module at the connection point and the battery cell whose + terminal is connected to the + side connection terminal of the low-voltage battery module, and makes it possible to measure the cell voltage of the battery cells of each battery module with higher accuracy than in the conventional example.

[0064] Furthermore, according to this embodiment, it is possible to measure and obtain the cell voltage of the battery cells of each battery module with high accuracy during charging and discharging, so that the battery control circuit 102 can perform cell balancing processing corresponding to the cell voltage during overcharging and overdischarging, respectively, during charging and discharging, with higher accuracy than in the conventional example.

[0065] In the above-described embodiment, the power supply system may be configured as shown in Fig. 10. Fig. 10 is a block diagram showing an outline of another configuration example of the power supply system according to the present invention. In a power supply system 10A in Fig. 10, a solar panel 2, a storage battery unit 3, and an EV stand 4 are each independently connected to power conditioners 1A, 1B, and 1C, respectively. In FIG. 10, each of power conditioners 1A, 1B, and 1C supplies or demands power (electrical energy) between a solar panel 2, a storage battery unit 3, and an EV stand 4, respectively, via a distribution board 6. The configuration and operation of the storage battery unit 3 in FIG. 10 are similar to those of the storage battery unit 3 in the present embodiment already described.

[0066] In the above-described embodiment, the power supply system may be configured as shown in Fig. 11. Fig. 11 is a block diagram showing an outline of another configuration example of the power supply system according to the present invention. In a power supply system 10B in Fig. 11, each of the solar panel 2 and the storage battery unit 3 is connected to a power conditioner 1D, and the EV stand 4 is connected to a power conditioner 1C. In FIG. 11, each of power conditioners 1C and 1D supplies or demands power (electrical energy) between a solar panel 2, a storage battery unit 3, and an EV stand 4, via a distribution board 6, respectively. The configuration and operation of the storage battery unit 3 in FIG. 11 are similar to those of the storage battery unit 3 in the present embodiment already described.

[0067] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0068] 100... Battery management device 101... Battery cell voltage measurement circuit 102... Battery control circuit 103, 104... Connection terminal 201, 202... Battery module Battery cell... 201_1, 201_2, 201_n-1, 201_n, 202_1, 202_2, 202_n-1, 202_n 201(-)... - side connection terminal 202(+)... + side connection terminal P11, P12, P1n-1, P1n, P1z, P21, P22, P2n-1, P2n, P2z... Measurement terminal R... Contact resistance R1, R2... Path resistance CP... Connection path

Claims

1. A battery management device that manages the voltage of each of the battery cells in a plurality of battery modules that are connected in series to form a storage battery, A battery cell voltage measurement circuit that measures the cell voltage of each of the battery cells, the battery cell voltage measurement circuit having measurement terminals to which the positive and negative terminals of each of the battery cells are independently connected, and measures the voltage difference between the measurement terminals as the cell voltage. Equipped with For each of the plurality of battery modules, In each of the battery cells connected in series, the negative terminal of the high-voltage battery cell and the positive terminal of the low-voltage battery cell adjacent to said battery cell are each set as one measurement point, while the negative terminal of the battery cell connected to the negative connection terminal of the battery module and the positive terminal of the battery cell connected to the positive connection terminal of the battery module are each set as one measurement point, The battery cell voltage measurement circuit includes: The negative terminal of a battery cell connected to the negative connection terminal of each of the plurality of battery modules and the positive terminal of a battery cell connected to the positive connection terminal of another battery module connected to the negative connection terminal of the battery module are each set as independent measurement points, and the potential difference between the independent measurement points is excluded from the measurement target as the cell voltage, and the potential difference between the measurement points corresponding to the positive terminal and the negative terminal of each of the battery cells in the plurality of battery modules connected in series is measured as the cell voltage. A battery management device characterized by:

2. A battery management method for managing the voltage of each of battery cells in a plurality of battery modules connected in series to form a storage battery, A battery cell voltage measurement process in which a battery cell voltage measurement circuit measures the cell voltage of each of the battery cells, the battery cell voltage measurement circuit has measurement terminals to which the + terminal and - terminal of each of the battery cells are independently connected, and the voltage difference between the measurement terminals is measured as the cell voltage. Including, For each of the plurality of battery modules, In each of the battery cells connected in series, the negative terminal of the high-voltage battery cell and the positive terminal of the low-voltage battery cell adjacent to said battery cell are each set as one measurement point, while the negative terminal of the battery cell connected to the negative connection terminal of the battery module and the positive terminal of the battery cell connected to the positive connection terminal of the battery module are each set as one measurement point, The battery cell voltage measurement circuit includes: The negative terminal of a battery cell connected to the negative connection terminal of each of the plurality of battery modules and the positive terminal of a battery cell connected to the positive connection terminal of another battery module connected to the negative connection terminal of the battery module are each set as independent measurement points, and the potential difference between the independent measurement points is excluded from the measurement target as the cell voltage, and the potential difference between the measurement points corresponding to the positive terminal and the negative terminal of each of the battery cells in the plurality of battery modules connected in series is measured as the cell voltage. A battery management method comprising:

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