Storage battery management device and storage battery management method

Abstract

To provide a storage battery management device that controls the deterioration of a connector by measuring a resistance value between connection paths that connect each battery module in a storage battery, and adjusts a current value during charging and discharging to suppress the generation of Joule heat.SOLUTION: A storage battery management device according to the present invention that manages a battery module connected in series constituting a storage battery includes a battery cell voltage measuring circuit that measures a potential difference between a negative connection terminal of the battery module and a positive connection terminal of another battery module in a connection path connecting the battery modules in series, and a storage battery control circuit that determines the resistance value of the connection path from the potential difference between the battery modules and the current value that flows through the connection path.SELECTED DRAWING: Figure 8

Description

Technical Field

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

Background Art

[0002] In recent years, in order to achieve energy savings, batteries are being operated to improve the utilization efficiency of electrical energy by storing the electric power generated by renewable energy, for example, the electric power generated by a solar cell (so-called solar panel), once in a battery and using it as needed. In addition, depending on the battery cells that make up the battery module used in the battery, for example, lithium-ion batteries, strict voltage management is required because the voltage values in the normal use area and the prohibited use area are close. Therefore, for the management of the voltage of the battery cells, the voltage of each battery cell (cell voltage) in each of the plurality of battery modules constituting the battery is measured, and cell balancing processing is performed for each battery cell (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as shown in FIG. 10, in a battery, between the - side connection terminal 201(-) of the high voltage side battery module 201 connected in series and the + side connection terminal 202(+) of the low voltage side battery module 202, a contact resistance R occurs in the connection path CP of the - side connection terminal 201(-) and the + side connection terminal 202(+). That is, this connection path CP includes the contact of the metal surfaces of the terminals at each of the connection (fastening) points of the connectors 211 and 621, the connection points of the connectors 611 and 111, the connection points of the connectors 112 and 612, and the connectors 622 and 212 (Figure 6 described later).

[0005] The contact resistance R is the resistance generated when metals are fastened (contacted) together, and is the resistance obtained by synthesizing the resistances at the contact locations of each of the above connectors. The above contact resistance has the characteristics that when it deteriorates over time or when foreign matter is mixed in during the installation of the connector, the resistance value increases, and when a current flows, the resistance value also increases. Therefore, when the contact resistance value becomes high, it becomes a high-temperature state due to Joule heat generated by the flowing current, and it is necessary to control so as not to exceed the heat-resistant temperature of connectors, cables, etc. with high thermal conductivity and small heat capacity.

[0006] Also, in each of the battery modules 201 and 202, when discharging or charging is not being performed, no current flows through the contact resistance R, so no potential is generated across the contact resistance R at the connection point. On the other hand, when charging or discharging is being performed on each of the battery modules 201 and 202, a current I as a charging current or a discharging current flows through the contact resistance R. 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 the contact resistance R, that is, between each of the - side connection terminal 201(-) and the + side connection terminal 202(+). Therefore, the - side connection terminal 201(-) of the battery module 201 and the + side connection terminal 202(+) of the battery module 202 are not at the same potential.

[0007] Also, the - terminal of the battery cell 201_n of the battery module 201 and the + terminal of the battery module 202, that is, the - side connection terminal 201(-) and the + 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 measure the voltage between the measurement terminals of the battery cell voltage measurement circuit 301 by connecting the connection points of the - terminals and + terminals of each of the battery cells connected in series as follows.

[0008] Here, in the connection path CP, the voltages between the - side connection terminal 201(-) of the battery module 201 and the + side connection terminal 202(+) of the battery module 202 are not the same due to the voltage drop caused by the above-described contact resistance. And there is a path resistance R1 due to the contact resistance and wiring resistance at the connection terminal 302 between the - side connection terminal 201(-) of the battery module 201 (i.e., the - terminal of the battery cell 201_n) and the measurement terminal P1z of the battery cell voltage measurement circuit 301. Similarly, there is a path resistance R2 due to the contact resistance and wiring resistance at the connection terminal 303 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 P1z of the battery cell voltage measurement circuit 301.

[0009] Also, as a reason why the deterioration of the connection path CP cannot be measured, usually, since the measurement circuit is configured only for the purpose of measuring and managing each cell voltage of the battery module, the connection path CP is not measured. Generally, the voltage of the connection path CP between the - side connection terminal 201(-) and the + side connection terminal 202(+) is ignored without measurement. Therefore, it is impossible to detect the deterioration (increase in resistance value) of the contact resistance between the serially connected modules. Also, as another reason, in many cases, the battery cell voltage measurement circuit is configured as one measurement circuit for one battery module, and since it is rare to connect two or more modules across one battery cell voltage measurement circuit, there is no room to measure the deterioration between the modules, and it is impossible to detect the deterioration (increase in resistance value) of the contact resistance.

[0010] Therefore, when charging or discharging is in progress, the voltage of path CP between the - side connection terminal 201(-) (the - terminal of battery cell 201_n) of the high - voltage - side battery module 201 connected in series and the + side connection terminal 202(+) (the + terminal of battery cell 202_1) of the low - voltage - side battery module 202 cannot be measured. For this reason, since the contact resistance R cannot be obtained, the degradation of path CP cannot be estimated, and during discharging and charging, the current value cannot be adjusted effectively to suppress heat generation due to Joule heat and prevent the heat - resistant temperature of connectors, cables, etc. with high thermal conductivity and small heat capacity from being exceeded.

[0011] The present invention has been made in view of such circumstances, and an object thereof is to provide a battery management device and a battery management method capable of measuring the contact resistance between connection paths (path CP) connecting each of battery modules in a storage battery, estimating the degradation of a connector in the connection path, and adjusting the current value during charging and discharging to suppress Joule heat in the contact resistance.

Means for Solving the Problems

[0012] One aspect of the battery management device of the present invention is a battery management device for managing battery modules connected in series that constitute a storage battery, and includes a battery cell voltage measurement circuit that measures the potential difference between the - side connection terminal of the battery module and the + side connection terminal of another battery module in the connection path that connects each of the battery modules in series, and a battery control circuit that obtains the resistance value of the connection path from the potential difference between the battery modules and the current value flowing through the connection path.

[0013] One aspect of the battery management device of the present invention is that the battery cell voltage measurement circuit includes measurement terminals to which the + terminal and the - terminal of each of the battery cells connected in series constituting the battery module are independently connected, and the - terminal of the battery cell on the high voltage side and the + terminal of the battery cell on the low voltage side are each set as one measurement point, and the potential difference between these measurement points is measured as the cell voltage, and the - terminal of the battery cell connected to the - side connection terminal and the + terminal of the battery cell connected to the + side connection terminal are each set as one path measurement point, and the potential difference between these path measurement points is measured as the potential difference of the connection path.

[0014] One aspect of the battery management method of the present invention is a battery management method for managing battery modules connected in series that constitute a storage battery. The battery cell voltage measurement circuit measures the potential difference between the - side connection terminal of the battery module and the + side connection terminal of another battery module in the connection path that serially connects each of the battery modules, and the battery control circuit includes a battery control process of obtaining the resistance value of the connection path from the potential difference between the battery modules and the current value flowing through the connection path.

Effect of the Invention

[0015] According to the present invention, it is possible to provide a battery management device and a battery management method capable of measuring the contact resistance between connection paths (path CP) connecting each of the battery modules in a storage battery, estimating the deterioration of the connector in the connection path, and adjusting the current value during charging and discharging to suppress the joule heat in the contact resistance.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. <Overall System> FIG. 1 is a block diagram showing the outline 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.

[0018] The power conditioner 1 performs processes such as conversion between DC power and AC power, control of the power supply voltage, power purchase, and power sale. That is, while the commercial power supply 5 uses an AC power supply, solar power generation and power storage use a DC power supply. Also, the voltage of the commercial power supply 5 is different from the voltage of the battery used in the solar panel 2 and the power storage unit 3. The power conditioner 1 performs conversion between DC power and AC power and control of the power supply voltage between the commercial power supply 5, the solar panel 2, and the power storage unit 3. Then, the power conditioner 1 supplies power to the distribution board 6, and the distribution board 6 distributes power to the outlets in each room.

[0019] The solar panel 2 can generate electricity during the time when the sun appears during the day, but cannot generate electricity at night when the sun sets, and the amount of electricity generated is not stable. The battery unit 3 can be charged from the grid via the commercial power supply 5 and the power conditioner 1 during the day, can be charged via the solar panel 2 and the power conditioner 1, and can also supplement the power supply via the power conditioner 1. The battery unit 3 can be charged from the grid via the commercial power supply 5 and the power conditioner 1 at night, and can also supplement the power supply via the power conditioner 1.

[0020] Also, when the power is insufficient, the power conditioner 1 purchases power from the commercial power supply 5, and when the power generated by the solar panel 2 becomes surplus, it sells power to the commercial power supply 5, performing processes such as power purchase and power sale.

[0021] Also, an EV (Electric Vehicle) stand 4 can be incorporated into the power system 10. The EV stand 4 can be used not only to charge an electric vehicle but also to accumulate power using the battery mounted on the electric vehicle. Also, the EV stand 4 can supplement the power supply via the power conditioner 1.

[0022] FIG. 2 is an explanatory diagram of the outline of the battery unit 3 used in the power supply system 10 according to the present invention. As shown in FIG. 2, the battery unit 3 is composed of, for example, seven battery modules 201 to 207 and a control management module 100. In the present embodiment, the configuration in which there are seven battery modules will be described as an example, but any number may be used as long as there are two or more. The battery modules 201 to 207 are provided with a battery stack composed of a plurality of battery cells. Further, the battery modules 201 to 202 are respectively provided with connectors 211 to 217 and connectors 221 to 222.

[0023] The control management module 100 manages the charge / discharge state and discharge state of the battery modules 201 to 207. The control management module 100 is provided with connectors 111 to 117 and connectors 121 to 127. The connectors 211 to 217 of the battery modules 201 to 207 and the connectors 111 to 117 of the control management module 100 are connected by relay cables 60-1 to 60-7 as shown in FIG. 3. The connectors 221 to 227 of the battery modules 201 to 207 and the connectors 121 to 127 of the control management module 100 are connected by relay cables 70-1 to 70-7 as shown in FIG. 4.

[0024] FIG. 3 is an explanatory diagram of the outline of the relay cable 60 (601 to 607) that connects the connectors 211 to 217 of the battery modules 201 to 207 and the connectors 111 to 117 of the control management module 100.

[0025] As shown in FIG. 3, the relay cable 60 is composed of a connector 61 (611 to 617) on the battery module 201 to 207 side, a connector 62 (621 to 627) on the control management module 100 side, and a cable 63 (631 to 63n) therebetween. The cable 63 (631 to 637) consists of two wires, a positive electrode wiring (+ side wiring) and a negative electrode wiring (- side wiring).

[0026] FIG. 4 is an explanatory diagram of an overview of relay cables 70 (70-1 to 70-7) that connect connectors 221 to 227 of battery modules 201 to 207 and connectors 121 to 127 of control management module 100.

[0027] As shown in FIG. 4, relay cables 70 (701 to 707) are composed of connectors 71 (711 to 717) on the battery module 201 to 207 side, connectors 72 (721 to 727) on the control management module 100 side, and cables 73 (731 to 737) therebetween. Cables 73 (731 to 737) are composed of a number of wirings corresponding to the battery cells constituting the battery stack.

[0028] FIG. 5 is a diagram showing a configuration example of battery modules 20 (201 to 207). Note that each of battery modules 201 to 207 has the same configuration. As shown in FIG. 5, battery modules 20 (201 to 207) are provided with a battery stack composed of battery cells 20_1 (201_1, 202_1), 20_2 (202_1, 202_2),..., 20_n (201_1, 201_n) connected in series.

[0029] As battery cells 20_1, 20_2,..., 20_n, lithium-ion batteries, for example, lithium iron phosphate ion batteries are used. Lithium iron phosphate ion batteries use lithium iron phosphate for the positive electrode (+ terminal side), and have the characteristics that the crystal structure is not easily collapsed even if there is heat generation inside the battery, and the safety is high. The cell voltage of one battery cell 20_1, 20_2,..., 20_n varies 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.

[0030] 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 performing charge and discharge of 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.

[0031] Figure 6 is a block diagram showing the configuration of the control management module 100. As shown in Figure 6, a terminal block 31, a breaker 33, an HV (High-Voltage) board 40, and a BMS (Battery Management System) board 50 are mounted on the control management module 100.

[0032] The terminal block 31 is a connector for connecting the 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 the ground potential. The wiring extending from the positive terminal 31a and the negative terminal 31b of the terminal block 31 forms charge and discharge lines 35a and 35b. The breaker 33 is for protection when a large current flows.

[0033] The communication connector 32 is a connector for connecting the shielded wire for communication from the power conditioner 1. The communication connector 32 is connected to the communication connector 51 on the BMS board 50. The data from the power conditioner 1 is received via the communication connector 32 and sent to the microprocessor 54. Also, the data from the microprocessor 54 is sent to the power conditioner 1 via the communication connector 32.

[0034] The HV board 40 is a board for performing charge and discharge of the battery modules 201 to 207. A relay 41, a current sensor 42, a communication connector 43, and connectors 221 to 227 are mounted on the HV board 40.

[0035] Relay 41 serves as a switch to start / stop the operation of the power storage unit 3. Current sensor 42 detects the charge / discharge current to battery modules 201 to 207. Communication connector 43 is connected to communication connector 52 on BMS board 50. Communication connector 43 transmits, for example, the detected current of current sensor 42 to microprocessor 54.

[0036] Connectors 111 to 117 are terminals that are respectively connected to connectors 211 to 217 on the battery module 201 to 207 sides. Connectors 211 to 217 on the battery module 201 to 207 sides are charge / discharge connectors. From connectors 111 to 117, wirings from both ends of battery cells 20_1, 20_2, …, 20_n that make up the battery stack are led out. And the + terminal of the connector 111 with the highest potential is connected to the charge / discharge line 35a, and the - terminal of the connector 117 with the lowest potential is connected to the charge / discharge line 35b.

[0037] Here, battery cell 20_1 represents each of battery cells 201_ to 207_1 in each of battery modules 201 to 207. The other battery cells 20_2, …, 20_n also represent each of the battery cells in each of battery modules 201 to 207 in the same way as the above-mentioned battery cell 20_1. Connectors 111 to 117 are connected in series so as to obtain a desired charge / discharge voltage.

[0038] BMS board 50 is a board for monitoring and controlling the states of battery modules 201 to 207. Communication connectors 51 and 52, AFE (Analog Front End) 53, microprocessor 54, photocoupler 55, and connectors 121 to 127 are mounted on BMS board 50.

[0039] Communication connector 51 is connected to communication connector 32 and performs data transmission and reception with power conditioner 1. Communication connector 52 is connected to communication connector 43 and performs data transmission and reception with HV board 40.

[0040] AFE53 corresponds to the battery cell voltage measurement circuit 101 described later, detects the cell voltage of each battery cell in each of the battery modules 201 to 207, and converts it into digital data.

[0041] The microprocessor 54 performs various controls based on data from the power conditioner 1, data from the HV board 40, data from the AFE53, etc.

[0042] The photocoupler 55 is an optical insulation element and connects between the AFE53 and the microprocessor 54. Since a high voltage is applied to the AFE53, isolation is performed between the AFE53 and the microprocessor 54 by the photocoupler 55. Also, an element such as a digital isolator may be used instead of the photocoupler 55.

[0043] The connectors 121 to 127 are terminals that connect to the connectors 221 to 227 on the battery module 201 to 207 sides, respectively. The connector 121 (121 to 127) is a connector for monitoring the cell voltages of the battery cells 20_1, 20_2,..., 20_n. The connectors 121 to 127 transmit the cell voltages of the battery modules 201 to 207 to the BMS board 50 side, respectively.

[0044] Figure 7 is a block diagram showing an overview of the AFE circuit element 530 arranged on the BMS board 50. In the present embodiment, the number of AFE circuit elements 530 as shown in Figure 7 is arranged corresponding to the battery modules 201 to 207 to realize the function of the AFE53. Here, among the functions of the AFE circuit element 530, only the parts necessary for the description of the present invention will be described.

[0045] In FIG. 7, terminals A1, A2, …, Am (m is an arbitrary integer) correspond to measurement terminals QP(+) to QP2n(−) in the battery cell voltage measurement circuit 101 described later, and are measurement terminals for detecting the cell voltage of each battery cell of the battery stack. When detecting the cell voltage of the battery stack, the battery cells are connected in order from terminal A1 to terminal Am such that the electrodes with the highest potential are from the highest potential electrode to the lowest potential electrode.

[0046] The resistance Ra and the switch circuit Sa between the stages of terminals A1, A2, …, Am are for performing a cell balance process for balancing the battery cells. That is, when the switch circuit Sa is turned on, both poles of the battery cell are connected via the resistance Ra, and the electrical energy stored in the battery cell is consumed as Joule heat. Thereby, the energy of the cell with a large charge amount among the battery cells can be consumed, and the charge amount and voltage of each battery cell can be equalized. Terminals D1 and D2 are terminals for data input and output. Data is input and output between the AFE53 (corresponding to the battery cell voltage measurement circuit 101 described later) and the microprocessor 54 (corresponding to the storage battery control circuit 102 described later) through terminals D1 and D2.

[0047] FIG. 8 is a block diagram showing an example of the schematic configuration of a storage battery management device for managing battery cells in a battery module according to an embodiment of the present invention. In FIG. 8, only each of the battery modules 201 and 202 in FIG. 6 is shown for simplicity of explanation. The storage battery management device 100 in FIG. 8 is provided on the BMS board 50 in FIG. 6, and includes a battery cell voltage measurement circuit 101 and a storage battery control circuit 102. Here, the battery cell voltage measurement circuit 101 is a circuit configured using the AFE53 (an aggregate of AFE circuit elements 530) in FIG. 6. The storage battery control circuit 102 is a circuit having battery control functions such as a cell balance process by the microprocessor 54 in FIG. 6.

[0048] In this embodiment, the voltage (cell voltage) of each battery cell of each of the two battery modules 201 and 202 will be described as being measured, and the measured cell voltage will be output to the storage battery control circuit 102. However, the number of battery modules is arbitrarily set according to the characteristics of the storage battery to be configured, and as shown in FIG. 6, a configuration in which three or more may be provided is also possible.

[0049] The battery cell voltage measurement circuit 101 measures the voltage (cell voltage) of each battery cell of the battery modules that make up the battery stack as the storage battery, for example, battery modules 201 and 202. Here, the battery cell voltage measurement circuit 101 measures the potential difference between each of the measurement terminals P11, P12, P13, …, P1n-1, P1n, P1z, P21, P22, P23, …, P2n-1, P2n, P2z as the cell voltage.

[0050] For this reason, by the connection terminal 103, each + terminal and - terminal of each battery cell of the battery module 201 are connected to the measurement terminals as the measurement points of the battery cell voltage measurement circuit 101. Similarly, by the connection terminal 104, each + terminal and - terminal of each battery cell of the battery module 202 are connected to the measurement terminals as the measurement points of the battery cell voltage measurement circuit 101. Also, the - side connection terminal 201(-) of the battery module 201 and the + side connection terminal 202(+) of the battery module 202 are connected in the connection path CP.

[0051] In the connection path CP, as already described in the conventional example, there is a contact resistance R at each contact surface of the terminals of each connector that connects the - side connection terminal 201(-) and the + side connection terminal 202(+). That is, the connection path CP includes each of the connection points of the connector 211 and the connector 621, the connection point of the connector 611 and the connector 111, the connection point of the connector 112 and the connector 612, and the connection point of the connector 622 and the connector 212 in FIG. 6, and the contact resistance R exists as the total value of the contact resistances at the contact surfaces in each connector.

[0052] To the measurement terminal P11 in the battery cell voltage measurement circuit 101, the + terminal of the battery cell 201_1 of the battery module 201 is connected. Also, to the measurement terminal P12, the - terminal of the battery cell 201_1 that constitutes the battery module 201 and the + terminal of the battery cell 201_2 are connected. To the measurement terminal P13, the - terminal of the battery cell 201_2 that constitutes the battery module 201 and the + terminal of the battery cell 202_3 (not shown) are connected.

[0053] To the measurement terminal P1n-1, the connection point between the - terminal of the battery cell 201_n-2 (not shown) that constitutes the battery module 201 and the + terminal of the battery cell 201_n-1 is connected. To the measurement terminal P1n, the connection point between the - terminal of the battery cell 201_n-1 and the + terminal of the battery cell 201_n of the battery module 201 is connected. To the measurement terminal P1z, the - terminal of the battery cell 201_n that constitutes the battery module 201, that is, the - side connection terminal 201(-) of the battery module 201 is connected.

[0054] Also, to the measurement terminal P21, the + terminal of the battery cell 202_1 that constitutes the battery module 202, that is, the + side connection terminal 202(+) of the battery module 202 is connected. Also, to the measurement terminal P22, the connection point between the - terminal of the battery cell 202_1 that constitutes the battery module 202 and the + terminal of the battery cell 201_2 is connected. To the measurement terminal P23, the - terminal of the battery cell 202_2 that constitutes the battery module 202 and the + terminal of the battery cell 202_3 (not shown) are connected.

[0055] To the measurement terminal P2n-1, the connection point between the - terminal of the battery cell 202_n-2 (not shown) that constitutes the battery module 202 and the + terminal of the battery cell 202_n-1 is connected. The connection point between the - terminal of the battery cell 202_n-1 that constitutes the battery module 202 and the + terminal of the battery cell 202_n is connected to the measurement terminal P2n. The - terminal of the battery cell 202_n that constitutes the battery module 202, that is, the - terminal 202(-) of the battery module 202, is connected to the measurement terminal P2z.

[0056] As a result, the battery cell voltage measurement circuit 101 measures the measurement voltage VS1_1 by measuring the voltage between each of the measurement terminals P11 and P12 as the cell voltage of the battery cell 201_1. Also, the battery cell voltage measurement circuit 1 measures the measurement voltage VS1_2 by measuring the voltage between each of the measurement terminals P12 and P13 as the cell voltage of the battery cell 201_2. The battery cell voltage measurement circuit 101 measures the measurement voltage VS1_n-1 by measuring the voltage between each of the measurement terminals P1n-1 and P1n as the cell voltage of the battery cell 201_n-1. The battery cell voltage measurement circuit 101 measures the measurement voltage VS1_n by measuring the voltage between each of the measurement terminals P1n and P1z as the cell voltage of the battery cell 201_n.

[0057] Also, the battery cell voltage measurement circuit 101 measures the voltage between each of the measurement terminals P21 and P22 as the measurement voltage VS2_1 of the battery cell 202_1. Also, the battery cell voltage measurement circuit 101 measures the voltage between each of the measurement terminals P22 and P23 as the measurement voltage VS2_2 of the battery cell 202_2. The battery cell voltage measurement circuit 101 measures the measurement voltage VS2_n-1 by measuring the voltage between each of the measurement terminals P2n-1 and P2n as the measurement voltage of the battery cell 202_n-1. The battery cell voltage measurement circuit 101 measures the measurement voltage VS2_n by measuring the voltage between each of the measurement terminals P2n and P2z as the measurement voltage of the battery cell 202_n.

[0058] That is, in this embodiment, when measuring the cell voltage of each battery cell, the - side connection terminal 201(-) of the battery module 201 on the high voltage side and the + side connection terminal 202 of the battery module 202 on the low voltage side in each of the battery modules 201 and 202 connected in series are each connected to different measurement terminals P1z and P21 of the battery cell voltage measurement circuit 101. On the other hand, the - terminal of the battery cell 201_n connected in series that constitutes each of the battery modules 201 and 202 and the + terminal of the battery cell 202_1 are each set as an independent measurement point for measuring the cell voltage, that is, they are connected to independent measurement terminals.

[0059] As described above, the battery management device of this embodiment measures the resistance value of the path CP that connects each of the battery modules 20 that make up the storage battery. The battery cell voltage measurement circuit 101 includes measurement terminals to which the + terminal and - terminal of the battery cell in the battery module are independently connected, and measures the potential difference between the measurement terminals. The battery control circuit 102 obtains the resistance value of the contact resistance R from the potential difference in the path CP between the battery modules 20 and the current value flowing through the path CP.

[0060] The battery cell voltage measurement circuit 101 connects the connection points of the - terminal of the battery cell on the high voltage side and the + terminal of the battery cell on the low voltage side in each of the battery cells connected in series that constitute each of the battery modules 20 to one measurement terminal, and measures the potential difference between the measurement terminals as the cell voltage. In addition, the battery cell voltage measurement circuit 101 sets the - terminal of the battery cell connected to the - side connection terminal in each of the battery modules 20 connected in series and the + terminal of the battery cell connected to the + side connection terminal of the battery module as one path measurement point each, and measures the potential difference between the path measurement points as the potential difference across the contact resistance R.

[0061] Also, the potential difference between each of the measurement terminals P1z and P21, that is, between the paths CP, is the voltage V generated by each of the current value of the current I and the resistance value of the contact resistance R at both ends of the contact resistance R, that is, between the terminal 201(-) of the battery module 201 and the terminal 202(+) of the battery module 202. Then, the battery cell voltage measurement circuit 101 measures the voltage between each of the measurement terminals P1z and P21, that is, the voltage V generated at both ends of the contact resistance R, and outputs the measured voltage V to the storage battery control circuit 102.

[0062] The storage battery control circuit 102 calculates and obtains the resistance value of the contact resistance R by dividing the voltage V generated at both ends of the contact resistance R supplied from the battery cell voltage measurement circuit 101 by the current value flowing through each of the battery modules 20. Here, the storage battery control circuit 102 obtains the resistance value of the contact resistance R in each of all the connection paths of the battery modules connected in series.

[0063] Also, when the resistance value of the obtained contact resistance R exceeds a preset resistance value (threshold value), since the heat generation due to the generated Joule heat affects the components constituting the storage battery, the storage battery control circuit 102 determines that it becomes impossible to flow the current of the required capacity in each of charging and discharging. Then, the storage battery control circuit 102 performs a process of notifying a warning or the like indicating that the resistance value of the contact resistance R has exceeded the preset resistance value and normal operation cannot be performed (for example, sounding a buzzer or lighting an emergency lamp).

[0064] Also, the storage battery control circuit 102 adjusts the current value of the current flowing through the contact resistance R in charging and discharging by using the resistance value of the contact resistance R, suppresses the generated Joule heat to less than a predetermined value, and performs control so that the temperature of the components constituting the storage battery does not exceed a predetermined value. Also, the storage battery control circuit 102 performs a process of calculating the above resistance value at a predetermined cycle (for example, in units of 6 months or 1 year) and accumulating a history. Then, the battery control circuit 102 estimates, for example, from the change curve of the resistance value of the accumulated contact resistance R, the period during which the resistance value of the contact resistance R exceeds a preset resistance value. When there is a connection path where the period during which the resistance value exceeds the preset resistance value is within a predetermined period range, the battery control circuit 102 performs a process of notifying a warning including the position of the connection path (for example, lighting an emergency lamp provided for each connection path).

[0065] Also, the battery cell voltage measurement circuit 101 outputs each of 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 battery module 201 to the battery control circuit 102. Also, the battery cell voltage measurement circuit 101 outputs each of the 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 battery module 202, to the battery control circuit 102.

[0066] Each of the battery cells causes an imbalance in the cell voltage during charging or discharging due to individual differences in characteristics such as individual capacity and leakage. When each of the measured cell voltages of the battery cells in the battery module is supplied from the battery cell voltage measurement circuit 101, the battery control circuit 102 performs a cell balancing process to suppress over - discharge during discharging and over - charging during charging corresponding to the cell voltage. Thereby, the battery control circuit 102 can perform the cell balancing process for highly accurate voltage management for each of the battery cells from the battery module 201 to the battery module 207 during both charging and discharging.

[0067] As described above, according to the present embodiment, in a storage battery configured by connecting a plurality of battery modules in series, the potential difference across the contact resistance R in the path between each of the battery modules is obtained, and the resistance value of the contact resistance R is measured from this potential difference. Therefore, it becomes possible to predict the Joule heat generated in the contact resistance R, and corresponding to the resistance value of the contact resistance R, the current value of the current flowing in charging or discharging can be easily controlled so that the temperature of the components of the storage battery falls below a predetermined value.

[0068] Further, according to the present embodiment, for each path connecting each of the battery modules, the history of the resistance value of the contact resistance R of the path obtained at a predetermined cycle is stored, and from the change curve of the resistance value obtained from the history, the cycle in which the resistance value of the contact resistance R exceeds a preset threshold value can be estimated. When the estimated cycle is included within a preset cycle range, a warning is generated. Therefore, it becomes possible to replace connectors or the like used in the path before the storage battery becomes unusable.

[0069] Also, in the above-described embodiment, the power supply system may have the configuration 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 the power supply system 10A of FIG. 10, each of the solar panel 2, the storage battery unit 3, and the EV stand 4 is independently connected to each of the power conditioners 1A, 1B, and 1C. In FIG. 10, each of the power conditioners 1A, 1B, and 1C supplies or supplies and demands power (electrical energy) between each of the solar panel 2, the storage battery unit 3, and the EV stand 4 via the distribution board 6. Regarding the configuration and operation of the storage battery unit 3 in FIG. 10, it is the same as the storage battery unit 3 in the present embodiment already described.

[0070] Also, in the above-described embodiment, the power supply system may have the configuration shown in FIG. 11. FIG. 16 is a block diagram showing an outline of another configuration example of the power supply system according to the present invention. In the power supply system 10B of FIG. 11, each of the solar panel 2 and the battery unit 3 is connected to the power conditioner 1D, and the EV stand 4 is connected to the power conditioner 1C. In FIG. 11, each of the power conditioners 1C and 1D supplies or supplies and demands power (electrical energy) between the solar panel 2, the battery unit 3, and the EV stand 4 via the distribution board 6. The configuration and operation of the battery unit 3 in FIG. 11 are the same as those of the battery unit 3 in the present embodiment already described.

[0071] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and designs and the like within the scope not departing from the gist of the present invention are also included.

Description of Reference Numerals

[0072] 100... Battery management device 101... Battery cell voltage measurement circuit 102... Battery control circuit 103, 104... Connection terminals 201, 202... Battery modules Battery cells... 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 terminals R... Contact resistance R1, R2... Path resistance CP... Connection path

Claims

1. A battery management device for managing battery modules connected in series to form a battery, a battery cell voltage measurement circuit that measures the potential difference between a - side connection terminal of one of the battery modules and a + side connection terminal of another battery module in a connection path in which each of the battery modules is connected in series via a connector; a battery control circuit that obtains a resistance value of the contact resistance of the connection path from the potential difference between the battery modules and the current value flowing through the connection path; and comprising: the battery control circuit notifies a warning when the resistance value of the contact resistance exceeds a preset resistance value. A battery management device characterized by the above.

2. The battery cell voltage measurement circuit includes measurement terminals to which the + terminal and - terminal of each battery cell connected in series to form the battery module are independently connected, and uses the - terminal of the battery cell on the high voltage side and the + terminal of the battery cell on the low voltage side as one measurement point each, measures the potential difference between these measurement points as the cell voltage, and uses the - terminal of the battery cell connected to the - side connection terminal and the + terminal of the battery cell connected to the + side connection terminal as one path measurement point each, and measures the potential difference between these path measurement points as the potential difference of the connection path. The battery management device according to Claim 1, characterized by the above.

3. A battery management method for managing battery modules connected in series to form a battery, a battery cell voltage measurement process in which a battery cell voltage measurement circuit measures the potential difference between a - side connection terminal of one of the battery modules and a + side connection terminal of another battery module in a connection path in which each of the battery modules is connected in series via a connector; a battery control process in which a battery control circuit obtains a resistance value of the contact resistance of the connection path from the potential difference between the battery modules and the current value flowing through the connection path; and including: in the battery control process, when the resistance value of the contact resistance exceeds a preset resistance value, the battery control circuit notifies a warning. A battery management method characterized by the above.

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