JP7716205B2 - Battery management device and battery management method - Google Patents

Description

The present invention relates to a storage battery management device and a storage battery management method.

In recent years, in order to conserve energy, storage batteries have been put into operation to 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 range and the prohibited use range are close to each other.
Therefore, in order to manage the voltage of the battery cells, the voltage (cell voltage) of each battery cell in each of the multiple battery modules that make up the storage battery is measured, and cell balancing processing is performed for each battery cell (see, for example, Patent Document 1).

JP 2013-68533 A

However, as shown in FIG. 10 , in the storage battery, contact resistance R occurs in the 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, this connection path CP includes the connection (fastening) points of connector 211 and connector 621, the connection points of connector 611 and connector 111, the connection points of connector 112 and connector 612, and the contact of the metal surfaces of the terminals in each of connectors 622 and 212 (Figure 6 described below).

The contact resistance R is the resistance that occurs when metals are fastened (contacted) to each other, and is the combined resistance of the resistances at each contact point of the connector.
The contact resistance has the characteristic that the resistance value increases with time degradation or if foreign matter gets mixed in when the connector is attached, and also increases when a current flows.
Therefore, if the contact resistance value becomes high, the Joule heat generated by the current flow will cause the temperature to rise, and it is necessary to control the temperature so that it does not exceed the heat resistance temperature of connectors and cables that have high thermal conductivity and small heat capacity.

Furthermore, when neither discharging nor charging is being performed in each of the battery modules 201 and 202, no current flows through the contact resistor R, and therefore no potential is generated across the contact resistor 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 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.

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 negative and positive 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 measure the voltage between the measurement terminals as the cell voltage.

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.
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 P1z of the battery cell voltage measurement circuit 301, there exists a path resistance R1 due to the contact resistance and wiring resistance at the connection terminal 302.
Similarly, a path resistance R2 due to contact resistance and wiring resistance at the connection terminal 303 exists between the positive connection terminal 202(+) of the battery module 202 (i.e., the positive terminal of the battery cell 202_1) and the measurement terminal P1z of the battery cell voltage measurement circuit 301.

Furthermore, the reason why deterioration of the connection path CP cannot be measured is that the battery module normally has a measurement circuit configured solely for the purpose of measuring and managing the voltage of each cell, and therefore the connection path CP is not measured.
Generally, the voltage of the connection path CP between the negative connection terminal 201(-) and the positive connection terminal 202(+) is ignored without being measured, making it impossible to detect deterioration of the contact resistance (increased resistance value) between modules connected in series.
Another reason is that in many cases, one battery cell voltage measurement circuit is provided for each battery module, and one battery cell voltage measurement circuit is rarely connected across two or more modules, so there is no room to measure deterioration between modules, and deterioration of contact resistance (increased resistance value) cannot be detected.

Therefore, when charging or discharging is taking place, it is not possible to measure the voltage of the path CP between the negative connection terminal 201(-) (negative terminal of battery cell 201_n) of the high-voltage side battery module 201 connected in series and the positive connection terminal 202(+) (positive terminal of battery cell 202_1) of the low-voltage side battery module 202.
For this reason, since it is not possible to calculate the contact resistance R, it is not possible to estimate the deterioration of the path CP, and it is not possible to effectively adjust the current value during discharging and charging to suppress heat generation due to Joule heat and to control the temperature so as not to exceed the heat resistance temperature of connectors and cables that have high thermal conductivity and small heat capacity.

The present invention was developed in light of these circumstances, and aims to provide a storage battery management device and method that can measure contact resistance between connection paths (paths CP) connecting each of the battery modules in a storage battery, estimate deterioration of connectors in the connection paths, and adjust current values during charging and discharging to suppress Joule heat at the contact resistance.

One aspect of the battery management device of the present invention is a battery management device that manages battery modules connected in series to form a storage battery, and includes a battery cell voltage measurement circuit that measures the potential difference between the negative connection terminal of one battery module and the positive connection terminal of another battery module in a connection path in which each of the battery modules is connected in series via a connector, and a battery control circuit that calculates the resistance value of the contact resistance of the connection path from the potential difference between the battery modules and the value of the current flowing through the connection path, and the battery control circuit estimates, for each connection path, the period in which the resistance value of the contact resistance exceeds a predetermined resistance value based on a change curve of the resistance value of the contact resistance calculated from a history of the resistance value of the contact resistance of the connection path calculated at predetermined cycles, and issues a warning including the position of the connection path in which the period in which the estimated resistance value is exceeded falls within the predetermined cycle range .

One aspect of the battery management device of the present invention is characterized in that the battery cell voltage measurement circuit has measurement terminals to which the + and - terminals of the serially connected battery cells that make up the battery module are independently connected, with the - terminal of the high-voltage battery cell and the + terminal of the low-voltage battery cell each being considered as one measurement point, measuring the potential difference between these measurement points 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 each being considered as one path measurement point, measuring the potential difference between these path measurement points as the potential difference of the connection path.

One aspect of the battery management method of the present invention is a battery management method for managing battery modules connected in series to form a storage battery, the method including: a battery cell voltage measurement process in which a battery cell voltage measurement circuit measures a potential difference between a negative connection terminal of a battery module and a positive connection terminal of another battery module in a connection path in which each of the battery modules is connected in series via a connector; and a battery control process in which a battery control circuit determines a resistance value of a contact resistance of the connection path from the potential difference between the battery modules and the value of a current flowing through the connection path, wherein in the battery control process, the battery control circuit estimates, for each connection path, a period in which the resistance value of the contact resistance exceeds a predetermined resistance value based on a change curve of the resistance value of the contact resistance determined from a history of determining and accumulating the resistance value of the contact resistance of the connection path at predetermined cycles, and notifies a warning including the position of the connection path in which the period in which the estimated resistance value is exceeded falls within the predetermined cycle range .

The present invention provides a storage battery management device and a storage battery management method that can measure the contact resistance between the connection paths (paths CP) connecting each of the battery modules in a storage battery, estimate deterioration of the connectors in the connection paths, and adjust the current value during charging and discharging to suppress Joule heat at the contact resistance.

1 is a block diagram showing an overview of a power supply system according to the present invention; 1 is an explanatory diagram illustrating an overview of a storage battery unit used in a power supply system according to the present invention. 10 is an explanatory diagram illustrating an outline of a relay cable connecting a connector of a battery module and a connector of a control management module. FIG. 10 is an explanatory diagram illustrating an outline of a relay cable connecting a connector of a battery module and a connector of a control management module. FIG. FIG. 2 is an explanatory diagram of an example of a battery module. FIG. 2 is a block diagram showing the configuration of a control management module. FIG. 2 is a block diagram showing an overview of an AFE circuit element disposed on a BMS substrate. 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. 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. FIG. 10 is a block diagram showing an outline of another configuration example of a power supply system according to the present invention. FIG. 10 is a block diagram showing an outline of another configuration example of a power supply system according to the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Overall system>
Fig. 1 is a block diagram showing an 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.

Power conditioner 1 converts between DC and AC power, controls power supply voltage, and purchases and sells electricity. Specifically, commercial power supply 5 uses AC power, while solar power generation and power storage use DC power. Furthermore, the voltage of commercial power supply 5 differs from the voltage of the batteries used in solar panels 2 and power storage units 3. Power conditioner 1 converts between DC and AC power and controls power supply voltage between commercial power supply 5, solar panels 2, and power storage units 3. Power conditioner 1 then supplies power to distribution board 6, which distributes the power to the outlets in each room.

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, resulting in an unstable amount of power generated. 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 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.

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

The power supply system 10 can also incorporate an EV (Electric Vehicle) stand 4. The EV stand 4 can be used to charge electric vehicles and also to store power using the batteries installed in the electric vehicles. The EV stand 4 can also supplement the power supply via the power conditioner 1.

2 is an explanatory diagram illustrating 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 to 207 and a control management module 100. In this embodiment, a configuration with seven battery modules will be described as an example, but any number of battery modules, two or more, may be used.
A battery stack made up of a plurality of battery cells is provided in the battery modules 201 to 207. The battery modules 201 to 202 are also provided with connectors 211 to 217 and connectors 221 to 222, respectively.

The control management module 100 manages the charge/discharge states and discharge states 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.

Figure 3 is an explanatory diagram showing the outline of the relay cables 60 (601-607) that connect the connectors 211-217 of the battery modules 201-207 to the connectors 111-117 of the control management module 100.

As shown in Figure 3, the relay cable 60 consists of connectors 61 (611-617) on the battery module 201-207 side, connectors 62 (621-627) on the control management module 100 side, and cables 63 (631-63n) between them. Cables 63 (631-637) consist of two wires: a positive wiring (+ side wiring) and a negative wiring (- side wiring).

Figure 4 is an explanatory diagram showing the 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 Figure 4, the relay cables 70 (701-707) consist of connectors 71 (711-717) on the battery module 201-207 side, connectors 72 (721-727) on the control management module 100 side, and cables 73 (731-737) between them. The cables 73 (731-737) consist of wires in a number corresponding to the number of battery cells that make up the battery stack.

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.

Battery cells 20_1, 20_2, ..., 20_n are lithium-ion batteries, for example, lithium iron phosphate ion batteries. 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 crystalline structure is resistant to collapse even when heat is generated inside the battery. The cell voltage of each battery cell 20_1, 20_2, ..., 20_n varies depending on the cell structure. In the case of lithium ion batteries, the cell voltage is 2V to 4V. In the case of lithium iron phosphate ion batteries, the cell voltage is, for example, around 3.3V.

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

Figure 6 is a block diagram showing the configuration of the control management module 100. As shown in Figure 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.

The terminal block 31 is a connector that connects the wiring from the power conditioner 1. The terminal block 31 is equipped 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. The wiring extending from the positive terminal 31a and negative terminal 31b of the terminal block 31 forms the charge/discharge lines 35a and 35b. The breaker 33 is used for protection when a large current flows.

The communication connector 32 is a connector that connects a 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. Data from the power conditioner 1 is received via the communication connector 32 and sent to the microprocessor 54. Data from the microprocessor 54 is also sent to the power conditioner 1 via the communication connector 32.

The HV board 40 is a board used to charge and discharge the battery modules 201-207. The HV board 40 is equipped with a relay 41, a current sensor 42, a communication connector 43, and connectors 221-227.

The relay 41 is a switch that starts and stops the operation of the energy storage unit 3. The current sensor 42 detects the charging and discharging current to 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.

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

Here, battery cell 20_1 refers to each of battery cells 201_ to 207_1 in each of battery modules 201 to 207. Other battery cells 20_2, ..., 20_n also refer to each of battery cells in each of battery modules 201 to 207, similar to the above-mentioned battery cell 20_1.
The connectors 111 to 117 are connected in series to obtain the desired charge and discharge voltage.

The BMS board 50 is a board for monitoring and controlling the status of the battery modules 201-207. The BMS board 50 is equipped with communication connectors 51 and 52, an AFE (Analog Front End) 53, a microprocessor 54, a photocoupler 55, and connectors 121-127.

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.

AFE 53 corresponds to the battery cell voltage measurement circuit 101 described below, and detects the cell voltage of each battery cell in each of the battery modules 201-207 and converts it into digital data.

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, etc.

The photocoupler 55 is an optical isolation element that connects the AFE 53 and the microprocessor 54. Because a high voltage is applied to the AFE 53, the photocoupler 55 provides isolation between the AFE 53 and the microprocessor 54. Alternatively, an element such as a digital isolator may be used instead of the photocoupler 55.

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

Figure 7 is a block diagram showing an overview of the AFE circuit element 530 arranged on the BMS board 50. In this embodiment, the functions of the AFE 53 are realized by arranging AFE circuit elements 530 as shown in Figure 7 in numbers corresponding to the battery modules 201 to 207. Note that the following explanation will be limited to the parts of the functions of the AFE circuit element 530 that are necessary for explaining the present invention.

In Figure 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 below, and are measurement terminals for detecting the cell voltage of each battery cell 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.

The resistor Ra and switch circuit Sa between 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 electrodes 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 most charge to be consumed, thereby equalizing 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 the AFE 53 (corresponding to a battery cell voltage measurement circuit 101 described later) and the microprocessor 54 (corresponding to a storage battery control circuit 102 described later) via terminals D1 and D2.

8 is a block diagram showing an example of the schematic configuration of a battery management device that manages battery cells in a battery module according to an embodiment of the present invention. For simplicity of explanation, only the battery modules 201 and 202 shown in FIG. 6 are shown in FIG.
The 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 battery control circuit 102. Here, the battery cell voltage measurement 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 battery control functions such as cell balancing processing by the microprocessor 54 in Fig. 6.

In this embodiment, the voltage (cell voltage) of each battery cell 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 can be set arbitrarily depending on the characteristics of the storage battery that constitutes it, and a configuration with three or more battery modules may also be provided, as shown in Figure 6.

The battery cell voltage measuring circuit 101 measures the voltage (cell voltage) of each of the battery cells of the battery modules that make up the battery stack as a storage battery, for example, the 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.

Therefore, the connection terminals 103 connect the + terminal and - terminal of each battery cell of the battery module 201 to the measurement terminals of the battery cell voltage measurement circuit 101 as measurement points.
Similarly, the connection terminals 104 connect the + and - terminals of each battery cell of the battery module 202 to measurement terminals serving as measurement points of the battery cell voltage measurement circuit 101 .
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.

As already explained in the conventional example, the connection path CP has a contact resistance R at the contact surface of each terminal of each connector connecting the negative connection terminal 201(-) and the positive connection terminal 202(+). That is, the connection path CP includes the connection point of connector 211 and connector 621, the connection point of connector 611 and connector 111, the connection point of connector 112 and connector 612, and the connection point of connector 622 and connector 212 in FIG. 6, and the contact resistance R is the sum of the contact resistances at the contact surfaces of each connector.

The positive terminal of the battery cell 201_1 of the battery module 201 is connected to a measurement terminal P11 in the battery cell voltage measurement circuit 101.
Furthermore, the negative terminal of the battery cell 201_1 and the positive terminal of the battery cell 201_2 that constitute the battery module 201 are connected to the measurement terminal P12.
The negative terminal of the battery cell 201_2 and the positive terminal of the battery cell 202_3 (not shown) that constitute the battery module 201 are connected to the measurement terminal P13.

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

Furthermore, the positive terminal of the battery cell 202_1 that constitutes 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, the connection point between the negative terminal of the battery cell 202_1 and the positive terminal of the battery cell 201_2 that constitute the battery module 202 is connected to the measurement terminal P22.
The negative terminal of the battery cell 202_2 and the positive terminal of the battery cell 202_3 (not shown) that constitute the battery module 202 are connected to the measurement terminal P23.

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

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

Furthermore, the battery cell voltage measurement circuit 101 measures the voltage between the measurement terminal P21 and the measurement terminal P22 as the measurement voltage VS2_1 of the battery cell 202_1.
Furthermore, the battery cell voltage measurement circuit 101 measures the voltage between the measurement terminal P22 and the measurement terminal P23 as the measurement 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.

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

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 measuring circuit 101 has measuring terminals to which the positive and negative terminals of the battery cells in the battery module are independently connected, and measures the potential difference between the measuring terminals.
The battery control circuit 102 calculates the resistance value of the contact resistance R from the potential difference in the path CP between the battery modules 20 and the value of the current flowing through the path CP.

The battery cell voltage measurement circuit 101 connects the connection point between the negative terminal of the high-voltage battery cell and the positive terminal of the low-voltage battery cell to one measurement terminal in each of the serially connected battery cells that make up each battery module 20, and measures the potential difference between the measurement terminals as the cell voltage.
Furthermore, the battery cell voltage measurement circuit 101 treats each of the negative terminals of the battery cells connected to the negative connection terminals of the battery modules 20 connected in series and the positive terminals of the battery cells connected to the positive connection terminals of the battery modules as one path measurement point, and measures the potential difference between the path measurement points as the potential difference across the contact resistance R.

Furthermore, the potential difference between each of the measurement terminals P1z and P21, i.e., the potential difference across the path CP, is the voltage V generated between the terminal 201(-) of the battery module 201 and the terminal 202(+) of the battery module 202, i.e., at both ends of the contact resistance R, due to the current value of the current I and the resistance value of the contact resistance R.
The battery cell voltage measurement circuit 101 then measures the voltage between the measurement terminal P1z and the measurement terminal P21, i.e., the voltage V generated across the contact resistance R, and outputs the measured voltage V to the storage battery control circuit 102.

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

Furthermore, if the resistance value of the determined contact resistance R exceeds a preset resistance value (threshold value), the battery control circuit 102 determines that the heat generated by Joule heat will affect the components that make up the battery, making it impossible to flow the required amount of current for each of charging and discharging.
Then, the battery control circuit 102 issues a warning (for example, by sounding a buzzer or turning on an emergency lamp) to indicate that the resistance value of the contact resistance R has exceeded a preset resistance value and normal operation is no longer possible.

In addition, the battery control circuit 102 uses the resistance value of the contact resistance R to adjust the current value of the current flowing through the contact resistance R during charging and discharging, suppressing the Joule heat generated to less than a predetermined value, and performing control to prevent the temperature of the components that make up the battery from exceeding a predetermined value.
The battery control circuit 102 also calculates the resistance value at predetermined intervals (for example, every six months or every year) and stores the calculation history.
The battery control circuit 102 then estimates, for example, from the change curve of the accumulated resistance value of the contact resistance R, the period in which the resistance value of the contact resistance R exceeds a preset resistance value, and if there is a connection path in which the period in which the resistance value is exceeded falls within a predetermined period range, it issues a warning including the location of the connection path (for example, by turning on an emergency lamp provided for each connection path).

In addition, the battery cell voltage measurement 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 measurement circuit 101 outputs the measured cell voltages VS2_1, VS2_2, ..., VS2_n-1, VS2n 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.

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 battery cell voltage measurement circuit 101 supplies the measured cell voltages of the battery cells in the battery module to the storage battery control circuit 102, the storage battery control circuit 102 performs cell balancing processing corresponding to the cell voltages to suppress over-discharge during discharge and over-charge during charge.
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.

As described above, according to this embodiment, in a storage battery configured with multiple battery modules connected in series, the potential difference across the contact resistance R in the path between each battery module is determined, and the resistance value of the contact resistance R is measured from this potential difference. This makes it possible to predict the Joule heat generated in the contact resistance R, and the current value flowing during charging and discharging can be easily controlled in accordance with the resistance value of the contact resistance R so that the temperature of the storage battery components remains below a predetermined value.

Furthermore, according to this embodiment, for each path connecting each battery module, a history of the resistance value of the contact resistance R of that path, calculated at each predetermined period, is stored. From the resistance value change curve calculated from this history, the period in which the resistance value of the contact resistance R exceeds a preset threshold can be estimated. If the estimated period falls within a preset period range, a warning is issued, making it possible to replace connectors, etc. used in the path before the storage battery becomes unusable.

Furthermore, 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 a power supply system 10A in Fig. 10, the solar panel 2, the storage battery unit 3, and the 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.

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, the solar panel 2 and the storage battery unit 3 are each 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 1</b>C and 1</b>D supplies or demands power (electrical energy) between solar panels 2 , storage battery units 3 , and EV stands 4 via a distribution board 6 .
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.

The above describes in detail an embodiment of the present invention with reference to the drawings, but the specific configuration is not limited to this embodiment and includes designs that do not deviate from the gist of the present invention.

100... Battery management device 101... Battery cell voltage measurement circuit 102... Battery control circuit 103, 104... Connection terminal 201, 202... Battery module Battery cells... 201_1, 201_2, 201_n-1, 201_n, 202_1, 202_2, 202_n-1, 202_n 201(-)... Negative connection terminal 202(+)... Positive 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 (3)

a battery management device that manages battery modules connected in series to form a storage battery;
a battery cell voltage measurement circuit that measures a potential difference between a negative connection terminal of one battery module and a positive 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 calculates a resistance value of a contact resistance of the connection path from a potential difference between the battery modules and a current value flowing through the connection path,
The battery management device is characterized in that the battery control circuit estimates a period in which the resistance value of the contact resistance exceeds a predetermined resistance value based on a change curve of the resistance value of the contact resistance obtained from a history of the contact resistance value of the connection path obtained at predetermined periods, and issues a warning including the position of the connection path in which the period in which the estimated resistance value is exceeded falls within a predetermined period . The battery management device according to claim 1, characterized in that the battery cell voltage measurement circuit includes measurement terminals to which the + terminals and - terminals of the battery cells connected in series that constitute the battery module are independently connected, the - terminal of the high-voltage side battery cell and the + terminal of the low-voltage side battery cell 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. A battery management method for managing battery modules connected in series that constitute a storage battery,
a battery cell voltage measurement process in which a battery cell voltage measurement circuit measures a potential difference between a negative connection terminal of one battery module and a positive 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 storage battery control process in which a storage battery control circuit calculates a resistance value of a contact resistance of the connection path from a potential difference between the battery modules and a current value flowing through the connection path;
a storage battery management method characterized in that, in the storage battery control process, the storage battery control circuit estimates a period in which the resistance value of the contact resistance exceeds a predetermined resistance value based on a change curve of the resistance value of the contact resistance obtained from a history of the contact resistance value of the connection path obtained at predetermined cycles, and issues a warning including the position of the connection path in which the period in which the estimated resistance value is exceeded is within a predetermined cycle range .