Battery module

Abstract

To provide a battery module that prevents the effects of a short circuit between output terminals from affecting battery cells.SOLUTION: A battery module supplies power to a load connected to an output terminal, and includes a power storage unit, a relay provided between the power storage unit and the output terminal and switching the electrical conduction / cut-off state between the power storage unit and the output terminal, and a control unit that controls the state of the relay, and the control unit controls the relay to a cut-off state when the output resistance of the battery module is equal to or greater than a first threshold value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a battery module that supplies power to a load connected to an output terminal.

Background Art

[0002] Patent Document 1 discloses a battery module in which a signal cutoff unit is disposed between a voltage sensing terminal electrically connected to an electrode terminal connection part of a battery cell and a conductive part connected to the voltage sensing terminal. In this battery module, when a short circuit occurs in the conductive part, the transmission of a detection voltage is interrupted using the signal cutoff unit, thereby improving safety.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the battery module described in Patent Document 1, since the battery cell and the conductive part (i.e., the voltage sensing terminal) are electrically connected, even if the transmission of the detection voltage is immediately interrupted when a short circuit occurs in the conductive part, there is a problem that the influence of the short circuit reaches the battery cell.

[0005] Therefore, in order to further improve the safety of the battery module, it is desirable to prevent the influence of a short circuit between output terminals from reaching the battery cell even when the output terminals are short-circuited.

[0006] The present disclosure has been made in view of the above problems, and an object thereof is to provide a battery module capable of preventing the influence when the output terminals are short-circuited from reaching the battery cell.

Means for Solving the Problems

[0007] In order to solve the above problems, one aspect of the disclosed technology is a battery module that supplies power to a load connected to an output terminal, including a power storage unit, a relay provided between the power storage unit and the output terminal for switching the electrical conduction / blocking state between the power storage unit and the output terminal, and a control unit for controlling the state of the relay. When the output resistance of the battery module is equal to or greater than a first threshold value, the control unit controls the relay to be in a blocked state. This is the battery module.

Effect of the Invention

[0008] According to the battery module of the present disclosure, when the output resistance of the battery module is equal to or greater than a first threshold value, it is determined that no load is connected to the output terminal of the battery module, and the relay is controlled to be in a blocked state to electrically disconnect the power storage unit from the output terminal. By this control, even if the output terminals are short-circuited, it is possible to prevent the influence of the short circuit from reaching the battery cells.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] When the battery module of the present disclosure is not connected to a load at the output terminal of the battery module, such as when it is transported alone, the battery cell stack (power storage unit) and the output terminal are kept in an electrically disconnected state. This can prevent the influence from reaching the battery cell stack even if the output terminals are short-circuited due to external factors. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [Configuration] FIG. 1 is a schematic diagram for explaining the configuration of a battery module 10 according to an embodiment of the present disclosure. The battery module 10 illustrated in FIG. 1 is a battery such as a secondary battery that can supply power to a load 30 connected between a plus-side output terminal 21 and a minus-side output terminal 22. This battery module 10 is used, for example, by being assembled to a vehicle or the like.

[0012] This battery module 10 includes a power storage unit 11, an output relay 12, a constant current circuit 13, a monitoring unit 14, a control unit 15, a current detection unit 16, and a voltage detection unit 17. In FIG. 1, power lines for power transfer are shown as solid lines, and signal lines through which detection values, control instructions, etc. flow are shown as dashed lines.

[0013] The power storage unit 11 is a secondary battery configured to be chargeable and dischargeable, such as a lithium-ion battery. This power storage unit 11 can have a stack configuration in which a plurality of lithium-ion battery cells are connected in series. The positive electrode of the power storage unit 11 is connected to the plus-side output terminal 21 via the output relay 12. The negative electrode of the power storage unit 11 is connected to the minus-side output terminal 22 through the current detection unit 16.

[0014] The output relay 12 is provided between the power storage unit 11 and the plus-side output terminal 21, and is a configuration for switching the electrical connection state (conductivity / interruption) between the power storage unit 11 and the plus-side output terminal 21. For this output relay 12, for example, a relay unit in which two field effect transistors (FETs) are connected in series with the rectification direction of the body diode reversed can be used. The conduction state and the interruption state of the output relay 12 are controlled by the control unit 15. Note that the output relay 12 may be provided between the power storage unit 11 and the minus-side output terminal 22.

[0015] The constant current circuit 13 is a circuit that can output a current of a constant value based on an instruction from the control unit 15. This constant current circuit 13 is connected in parallel with the output relay 12 and has the role of a bypass that connects the power storage unit 11 and the positive output terminal 21 when performing connection diagnosis control described later. Note that a well-known circuit can be used for the constant current circuit 13.

[0016] The monitoring unit 14 is a configuration for monitoring the state of the power storage unit 11, for example, a monitoring IC. This monitoring unit 14 can acquire information on the voltage (such as the voltage of each battery cell) from the power storage unit 11 and information on the current flowing through the power storage unit 11 from the current detection unit 16. The information acquired by the power storage unit 11 is output to the control unit 15.

[0017] The control unit 15 is a configuration for controlling the output relay 12 and the constant current circuit 13, for example, a microcomputer. This control unit 15 controls the operations of the output relay 12 and the constant current circuit 13 based on the information on the state of the power storage unit 11 acquired from the monitoring unit 14 and the voltage between the positive output terminal 21 and the negative output terminal 22 acquired from the voltage detection unit 17.

[0018] The current detection unit 16 is a configuration for detecting the current flowing out of the power storage unit 11 (outflow current) and the current flowing into the power storage unit 11 (inflow current), for example, a current sensor.

[0019] The voltage detection unit 17 is a configuration for detecting the voltage that appears between the positive output terminal 21 and the negative output terminal 22 (hereinafter referred to as "voltage between output terminals"), for example, a voltage sensor.

[0020] Some or all of the configurations of the above-described output relay 12, constant current circuit 13, monitoring unit 14, control unit 15, current detection unit 16, and voltage detection unit 17 operate by receiving power supply from the power storage unit 11.

[0021] [Control] Next, with further reference to FIGS. 2 and 3, the control performed by the battery module 10 according to the present embodiment will be described. FIG. 2 is a flowchart for explaining the processing procedure of connection diagnosis control executed by the control unit 15 of the battery module 10. FIG. 3 is a diagram for explaining an example of the result of performing the connection diagnosis control of FIG. 2.

[0022] The connection diagnosis control shown in FIG. 2 is executed at a predetermined timing during a period when the load 30 is not connected between the positive output terminal 21 and the negative output terminal 22 of the battery module 10. Examples of the state where the load 30 is not connected between the positive output terminal 21 and the negative output terminal 22 include a scene where the battery module 10 is transported alone. Also, examples of the predetermined timing include a timing that arrives at a constant cycle. In a state where the load 30 is not connected between the positive output terminal 21 and the negative output terminal 22, the output relay 12 is controlled to be in an off state (OFF) by the control unit 15, and the constant current circuit 13 is controlled to be in a non-operating state.

[0023] (Step S201) The control unit 15 operates the constant current circuit 13 to perform constant current control in which a current of a certain value serving as a test current flows from the power storage unit 11 toward the positive output terminal 21 for a certain period of time. The certain value and the certain period of time are set to appropriate values in consideration of battery overcharge avoidance, output response performance, etc., based on the power storage amount of the power storage unit 11 and the capacitance component connected to the power supply destination such as the load 30. When the constant current control by the constant current circuit 13 is performed by the control unit 15, the process proceeds to step S202.

[0024] (Step S202) The control unit 15 acquires the voltage between the output terminals of the battery module 10 from the voltage detection unit 17, and acquires the outflow current of the power storage unit 11 from the monitoring unit 14. When the voltage between the output terminals and the outflow current are acquired by the control unit 15, the process proceeds to step S203.

[0025] (Step S203) Based on the voltage between the output terminals and the outflow current, the control unit 15 derives the impedance Z, which is the output resistance of the battery module 10. This impedance Z can be derived using general laws (such as Ohm's law). Also, the derivation of the impedance Z may be performed constantly while the constant current control is being carried out by the constant current circuit 13, or may be performed when a certain period of time has elapsed and the constant current control ends. When the impedance Z is derived by the control unit 15, the process proceeds to step S204.

[0026] (Step S204) The control unit 15 determines the value of the impedance Z of the battery module 10. This determination is made by comparing the impedance Z with a first threshold value a and a second threshold value b. The first threshold value a is set to a large resistance value that can determine that no load 30 is connected between the positive output terminal 21 and the negative output terminal 22 of the battery module 10. The second threshold value b is a value smaller than the first threshold value a, and is set to a small resistance value that can determine that there is a short between the positive output terminal 21 and the negative output terminal 22 of the battery module 10. The determination of the value of the impedance Z can be made at any time when the impedance Z is constantly derived in step S203 above, and can be made at the time when the constant current control ends when it is derived at the time when a certain period of time has elapsed.

[0027] When the control unit 15 determines that the value of the impedance Z is greater than or equal to the first threshold value a (step S204, a ≤ Z), the process proceeds to step S205. Also, when the control unit 15 determines that the value of the impedance Z is less than the second threshold value b (step S204, Z < b), the process proceeds to step S206. On the other hand, when the control unit 15 determines that the value of the impedance Z is less than the first threshold value a and greater than or equal to the second threshold value b (step S204, b ≤ Z < a), the process proceeds to step S207.

[0028] (Step S205) Since the impedance Z of the battery module 10 has a high resistance value, the control unit 15 determines that the battery module 10 is in a "terminal open" state where no load 30 is connected between the positive output terminal 21 and the negative output terminal 22. In other words, it is determined that the battery module 10 is not assembled in a vehicle or the like. When the control unit 15 makes a terminal open determination, the process proceeds to step S208.

[0029] (Step S206) Since the impedance Z of the battery module 10 has a low resistance value, the control unit 15 determines that the battery module 10 is in a "terminal short" state where there is a short circuit between the positive output terminal 21 and the negative output terminal 22. When the control unit 15 makes a terminal short determination, the process proceeds to step S208.

[0030] (Step S207) Since the impedance Z of the battery module 10 has an intermediate resistance value, the control unit 15 determines that the battery module 10 is in a "terminal connected" state where a load 30 is connected between the positive output terminal 21 and the negative output terminal 22. In other words, it is determined that the battery module 10 is assembled in a vehicle or the like. When the control unit 15 makes a terminal connection determination, the process proceeds to step S209.

[0031] (Step S208) The control unit 15 controls the output relay 12 to the off state (OFF). By this control, the power storage unit 11 is electrically disconnected from the positive output terminal 21. When the control unit 15 controls the output relay 12 to the off state (OFF), the process proceeds to step S201.

[0032] (Step S209) The control unit 15 controls the output relay 12 to be in the conducting state (ON). By this control, the power storage unit 11 is electrically connected to the positive output terminal 21, enabling power supply from the battery module 10 to the load 30. When the output relay 12 is controlled by the control unit 15 to be in the conducting state (ON), the connection diagnosis control ends.

[0033] In addition, when the battery module 10 is assembled to a vehicle or the like and the connection diagnosis control ends, if the control unit 15 can detect that the battery module 10 has been removed from the vehicle or the like, the above-described connection diagnosis control may be started again.

[0034] Fig. 3 shows an image of terminal open determination, terminal short determination, and terminal connection determination based on comparison of the impedance Z of the battery module 10 with a first threshold value a and a second threshold value b.

[0035] <Function and Effect> As described above, according to the battery module 10 according to an embodiment of the present disclosure, an output relay 12 and a constant current circuit 13 connected in parallel between the power storage unit 11 and the positive output terminal 21 are provided, and connection diagnosis control of the output terminal using a test current by the constant current circuit 13 is performed. Then, as a result of the connection diagnosis control, if it can be determined that a load 30 is connected between the positive output terminal 21 and the negative output terminal 22 of the battery module 10, the output relay 12 is made conductive. By this control, power supply from the battery module 10 to the load 30 is enabled.

[0036] On the other hand, according to the battery module 10 according to this embodiment, as a result of the connection diagnosis control, if it is determined that a load 30 is not connected between the positive output terminal 21 and the negative output terminal 22 of the battery module 10, or if it is determined that the positive output terminal 21 and the negative output terminal 22 of the battery module 10 are short-circuited, the output relay 12 is cut off. By this control, even if the output terminals of the battery module 10 are short-circuited, it is possible to prevent the influence of the short circuit from reaching the power storage unit 11.

Industrial Applicability

[0037] The battery module of the present disclosure can be used when it is desired to prevent the influence of a short circuit between output terminals from reaching the battery cells, etc.

Explanation of Reference Numerals

[0038] 10 Battery module 11 Power storage unit 12 Output relay 13 Constant current circuit 14 Monitoring unit 15 Control unit 16 Current detection unit 17 Voltage detection unit 21, 22 Output terminals 30 Load

Claims

1. A battery module that supplies power to a load connected to an output terminal, comprising: a power storage unit; a relay provided between the power storage unit and the output terminal, for switching the electrical conduction / interruption state between the power storage unit and the output terminal; a control unit for controlling the state of the relay, wherein the control unit controls the relay to an off state when the output resistance of the battery module is equal to or greater than a first threshold value.

2. further comprising a constant current circuit connected in parallel with the relay, wherein the control unit periodically performs control to flow a constant current from the power storage unit to the output terminal through the constant current circuit during a period when the relay is in an off state, and derives the output resistance based on the outflow current of the power storage unit and the voltage of the output terminal in this control. The battery module according to claim 1.

3. The battery module according to claim 1 or 2, wherein the control unit controls the relay to an off state when the output resistance is less than a second threshold value that is less than the first threshold value.

4. The battery module according to claim 3, wherein the control unit controls the relay to an on state when the output resistance is equal to or greater than the second threshold value and less than the first threshold value.

5. The battery module according to claim 4, wherein the control unit controls the relay to an off state when detecting that the load has been removed from the output terminal.

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