Power device, power device control method, program, and storage medium

Abstract

To provide a power device and a control method thereof having a plurality of power storage units, which prevents deterioration and failure of the power storage units and extends the life of the power storage units.SOLUTION: In a power device (10), an ECU (14) acquires voltage values of a plurality of power storage units (12a to 12d), and when a voltage difference between the acquired voltage values of the plurality of power storage units (12a to 12d) exceeds a threshold, prohibits connection between the plurality of power storage units (12a to 12d) whose voltage difference exceeds the threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power device having a plurality of power storage units and a control method thereof.

Background Art

[0002] A power device in which a plurality of batteries (power storage units) are connected in parallel to each other via a voltage converter is disclosed in, for example, Japanese Patent Application Laid-Open No. 2016-25791.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when connecting a plurality of power storage units having different voltages or SOCs (state of charge) in parallel to each other, charge and discharge is performed such that current flows in proportion to the voltage difference between the power storage units so that the voltages or SOCs become equal to each other between the plurality of power storage units. In this case, when the plurality of power storage units are simply connected, if the voltage difference is negligibly small, there is no problem even if the power storage units are directly connected in parallel.

[0005] However, when connecting a plurality of power storage units having a large voltage difference in parallel, a large current flows due to the voltage difference. As a result, deterioration or failure of the power storage unit may occur, and the life of the power storage unit may be shortened. For example, a lead battery has a high internal resistance, so even if there is a voltage difference, a large current (overcurrent) hardly flows. On the other hand, for a power storage unit with a low internal resistance such as a detachable lithium-ion battery, when connected in parallel for charge and discharge, a large current (overcurrent) easily flows.

[0006] The present invention has been made in consideration of such problems, and an object thereof is to provide a power device and a control method thereof that can achieve a long life of a power storage unit by preventing deterioration and failure of the power storage unit in advance.

Means for Solving the Problems

[0007] A first aspect of the present invention is a power device having a plurality of power storage units, the power device including a voltage acquisition unit configured to acquire voltage values of the plurality of power storage units respectively, and a connection control unit configured to prohibit connection between the plurality of power storage units when a voltage difference between the voltage values of the plurality of power storage units acquired by the voltage acquisition unit exceeds a voltage threshold value.

[0008] A second aspect of the present invention is a control method for a power device having a plurality of power storage units, the control method including a step of acquiring voltage values of the plurality of power storage units respectively by a voltage acquisition unit, and a step of prohibiting connection between the plurality of power storage units when a voltage difference between the voltage values of the plurality of power storage units acquired by the voltage acquisition unit exceeds a voltage threshold value by a connection control unit.

Effects of the Invention

[0009] According to the present invention, when a voltage difference between voltage values of a plurality of power storage units exceeds a voltage threshold value, connection between the plurality of power storage units is prohibited. As a result, a large current flowing due to the voltage difference is avoided. As a result, deterioration and failure of the power storage unit are prevented in advance, and a long life of the power storage unit can be realized.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of a power device and a control method thereof according to the present invention will be exemplified and described with reference to the accompanying drawings.

[0012] [1. Schematic Configuration of this Embodiment] As shown in FIG. 1, the power device 10 according to this embodiment includes a plurality of power storage units 12, an ECU 14 (voltage acquisition unit, connection control unit, temperature acquisition unit), a notification unit 16, a built-in battery 18, and a plurality of switches 20 and 22. In FIG. 1, a case where four power storage units 12 (hereinafter, may be referred to as the first to fourth power storage units 12a to 12d) are arranged is illustrated. In this embodiment, at least two power storage units 12 may be arranged in the power device 10.

[0013] Further, the power device 10 is applied to a power supply system of various electric vehicles such as motorcycles, bicycles, tricycles, and four-wheeled vehicles. Note that the power device 10 is not limited to being applied to electric vehicles. (1) Moving bodies such as aircraft and ships other than vehicles, (2) Various charging facilities such as household chargers, (3) Various dischargers that output power from the power storage unit 12, (4) Various work machines such as general-purpose work machines, lawn mowers, and cultivators, (5) The power device 10 can also be applied to a power supply system (Energy Storage System) that supplies power to various electrical devices installed or arranged inside and outside buildings such as houses. In the following description, mainly, the case where the power device 10 is applied to an electric vehicle will be described.

[0014] Each power storage unit 12 is a power storage device that is detachable from the power device 10 and can be charged and discharged. For example, a battery pack of a detachable lithium-ion battery is suitable as the power storage unit 12. Each power storage unit 12 is connected in parallel to loads 24 (power utilization units) such as the motor and PDU of the electric vehicle. That is, the positive terminal on the output side of each power storage unit 12 is connected to the positive terminal of the load 24. The negative terminal on the output side of each power storage unit 12 is connected to the negative terminal of the load 24. Note that the load 24 is not limited to the motor and PDU, and any device that utilizes the power of the plurality of power storage units 12 may be used.

[0015] The built-in battery 18 is a fixed-type power storage device provided in the power device 10. The built-in battery 18 is connected in parallel to the load 24 via the switch 20. That is, the positive terminal of the built-in battery 18 is connected to the positive terminal of the load 24 via the switch 20. The negative terminal of the built-in battery 18 is connected to the negative terminal of the load 24. Note that a voltage conversion circuit (not shown) such as a DC / DC converter may be inserted between the built-in battery 18 and the load 24. Thereby, when supplying power to the load 24 from both the power storage units 12 and the built-in battery 18, the voltage of the built-in battery 18 can be adjusted by the voltage conversion circuit, and the adjusted voltage can be output to the load 24 side. Also, when the built-in battery 18 supplies power to the load 24 alone or when the power storage units 12 supply power to the load 24, the voltage conversion circuit may not be provided.

[0016] The built-in battery 18 is the main power source of the power device 10 and is also a starting power source for starting each power storage unit 12. Therefore, the built-in battery 18 is also connected to each power storage unit 12 via each switch 22. That is, the positive terminal of the built-in battery 18 is connected to the positive power terminal of each power storage unit 12 via each switch 22. The negative terminal of the built-in battery 18 is connected to the negative power terminal of each power storage unit 12.

[0017] ECU14 is an electronic control unit of an electric vehicle, and realizes various functions such as connection control for each switch 26 (see FIG. 2) described later by reading and executing a program stored in a non-transitory storage medium (not shown). Further, the notification unit 16 is an output device such as a display device or a speaker provided in the electric vehicle, and notifies the outside (for example, the user of the electric vehicle) of the processing result of the ECU14.

[0018] The ECU14, each power storage unit 12, each switch 20, 22, and the load 24 can transmit and receive signals or information via the communication line 28 of the Controller Area Network (CAN). Therefore, the ECU14 controls each switch 20, 22 to turn them on, thereby electrically connecting the built-in battery 18 and the load 24, or electrically connecting the built-in battery 18 and each power storage unit 12.

[0019] FIG. 2 is an internal configuration diagram of each power storage unit 12. Each power storage unit 12 has the same configuration, and in FIG. 2, only one power storage unit 12 is shown. As shown in FIG. 2, each power storage unit 12 is a battery pack that houses a switch 26 (connection part), a battery 30, a battery management system (BMU) 32, a resistor 34, a temperature sensor 36, and a communication unit 38.

[0020] The positive electrode of the battery 30 is connected to the positive electrode terminal of the load 24 via the switch 26 and the positive electrode terminal of the power storage unit 12. The negative electrode of the battery 30 is connected to the negative electrode terminal of the load 24 via the resistor 34 and the negative electrode terminal of the power storage unit 12. Further, the communication unit 38 transmits and receives signals or information to and from the ECU14 via the communication line 28.

[0021] The BMU32 is activated when the switch 22 is turned on under the control of the ECU14 and power is supplied from the built-in battery 18. The BMU32 monitors the battery 30 and the like. Specifically, the BMU32 turns on the switch 26 based on a control signal received by the communication unit 38 via the communication line 28 from the ECU14, thereby electrically connecting the battery 30 and the load 24. Further, the BMU32 sequentially detects the voltage values at both ends of the resistor 34, and sequentially calculates the current value of the current (discharge current or charge current) flowing through the battery 30 based on the detected voltage values and the resistance value of the resistor 34. Furthermore, the BMU32 sequentially detects the voltage value of the battery 30, and sequentially calculates the SOC of the battery 30 based on the detected voltage value and the calculated current value. Additionally, the BMU32 sequentially acquires the temperature of the battery 30 detected by the temperature sensor 36 such as a thermistor. The BMU32 sequentially transmits information including the voltage value, current value, SOC, and temperature to the ECU14 via the communication line 28 from the communication unit 38.

[0022] Therefore, the ECU14 sequentially acquires the above information, and determines (judges) whether it is necessary to turn on (connect) or off (disconnect) each switch 26 based on each acquired information. Further, the ECU14 transmits a control signal based on this determination result to each communication unit 38 via the communication line 28, thereby turning on or off the switch 26 of each power storage unit 12. Furthermore, the ECU14 transmits a control signal to each of the switches 20, 22 via the communication line 28, thereby turning on or off each of the switches 20, 22.

[0023] [2. Operation of this Embodiment] The operation of the power device 10 according to this embodiment configured as described above (control method of the power device 10) will be described with reference to FIG. 3. This operation prohibits the connection between the power storage units 12 when the voltage difference between the voltage values of the plurality of power storage units 12 (see FIGS. 1 and 2) exceeds the voltage threshold, thereby avoiding a large current (overcurrent) exceeding the allowable current caused by the voltage difference from flowing within the power device 10 including between the respective power storage units 12. The voltage threshold is a threshold for determining whether a large current (overcurrent) flowing between the respective power storage units 12 is generated due to the voltage difference, and refers to the value of the voltage difference corresponding to the allowable current. Therefore, if the voltage difference is within the voltage threshold, the generation of overcurrent is suppressed. On the other hand, if the voltage difference exceeds the voltage threshold, there is a possibility of overcurrent generation.

[0024] In this operation description, the case of supplying power from each power storage unit 12 to the load 24 when the connection between the built-in battery 18 and the load 24 is cut off by turning off the switch 20 will be described. Note that when the built-in battery 18 and the load 24 are connected by turning on the switch 20, it should be noted that the built-in battery 18 supplies power to the load 24 via a voltage conversion circuit (not shown).

[0025] In step S1, the ECU 14 supplies a control signal to each switch 22 to switch each switch 22 from off to on. Thereby, the built-in battery 18 and the BMU 32 of each power storage unit 12 are electrically connected, and power supply from the built-in battery 18 to each power storage unit 12 (BMU 32) is started. Thereby, each BMU 32 is activated. Also, each communication unit 38 reaches a state where it can communicate with the ECU 14 via the communication line 28 (step S1: YES). Note that in step S1, the ECU 14 and each power storage unit 12 may perform numbering processing for assigning an ID number or the like to each power storage unit 12 via the communication line 28.

[0026] In step S2, the BMU 32 of each power storage unit 12 detects the voltage value of the battery 30. In this case, each BMU 32 also acquires the temperature of the battery 30, calculates the current value of the current flowing through the battery 30, and calculates the SOC of the battery 30. Therefore, each BMU 32 transmits this information from the communication unit 38 to the ECU 14 via the communication line 28. Accordingly, the ECU 14 can acquire information such as the voltage value of the battery 30 from each power storage unit 12.

[0027] In step S3, the ECU 14 determines whether a plurality of power storage units 12 are arranged (accommodated) in the power device 10. In this case, for example, the ECU 14 instructs each power storage unit 12 to transmit information via the communication line 28, and when receiving some information from each power storage unit 12 via the communication line 28 in response to this instruction, it determines that each power storage unit 12 is accommodated in the power device 10.

[0028] When it is determined that at least two power storage units 12 are accommodated (step S3: YES), in the next step S4, the ECU 14 determines whether there are a plurality of available power storage units 12 among all the accommodated power storage units 12. In this case, for example, when the voltage value of the battery 30 is equal to or higher than a predetermined value, or the SOC is equal to or higher than a predetermined value, the ECU 14 determines that the power storage unit 12 having the battery 30 is available.

[0029] When it is determined that there are a plurality of available power storage units 12 (step S4: YES), in the next step S5, the ECU 14 compares the voltage values of the batteries 30 of each power storage unit 12, and determines whether the voltage difference between the highest voltage value (maximum voltage value) and the lowest voltage value (minimum voltage value) is within the voltage threshold.

[0030] Here, if the voltage difference between the maximum voltage value and the minimum voltage value is within the voltage threshold (step S5: YES), the process proceeds to step S7. That is, the ECU 14 determines that there is a possibility that no overcurrent will occur even if all the power storage units 12 are connected in parallel to the load 24.

[0031] Also, when the voltage difference between the maximum voltage value and the minimum voltage value exceeds the voltage threshold (step S5: NO), the ECU 14 proceeds to step S6, compares the voltage values of the batteries 30 of each power storage unit 12, and determines whether there is at least one combination of connections of two or more power storage units 12 that results in a voltage difference within the voltage threshold. If there is a combination of connections that results in a voltage difference within the voltage threshold (step S6: YES), it proceeds to step S7. That is, in this case of the combination of connections, since the voltage values of each other are close (adjacent), the ECU 14 determines that no overcurrent may occur if at least two power storage units 12 are connected in parallel.

[0032] In step S7, the ECU 14 compares the temperatures of the batteries 30 of each power storage unit 12 and determines whether the temperature difference between the highest temperature (maximum temperature) and the lowest temperature (minimum temperature) is within the temperature threshold. That is, if the internal resistance of the battery 30 changes according to the temperature of the battery 30, the voltage value of the battery 30 also changes. Therefore, in the present embodiment, in consideration of the temperature of the power storage unit 12 (battery 30), a combination of connections of the power storage units 12 is selected.

[0033] Note that the temperature threshold is a threshold for determining whether a large current (overcurrent) flowing between each power storage unit 12 is generated due to a voltage difference corresponding to the temperature difference, and refers to the value of the temperature difference corresponding to the allowable current. Therefore, if the temperature difference is within the temperature threshold, the generation of overcurrent is suppressed. On the other hand, if the temperature difference exceeds the temperature threshold, there is a possibility that an overcurrent may occur.

[0034] When the temperature difference between the highest temperature and the lowest temperature is within the temperature threshold (step S7: YES), the ECU 14 determines that no overcurrent will occur even if at least two power storage units 12 are connected in parallel to the load 24, provided that it is the combination of connections with positive determination results in steps S5 and S6, and proceeds to step S9.

[0035] Also, when the temperature difference between the maximum temperature and the minimum temperature exceeds the temperature threshold (step S7: NO), the ECU 14 proceeds to step S8, compares the temperatures of the batteries 30 of each power storage unit 12, and determines whether there is at least one combination of connections of two or more power storage units 12 that results in a temperature difference within the temperature threshold. If there is a combination of connections that results in a temperature difference within the temperature threshold (step S8: YES), it proceeds to step S9. That is, the ECU 14 determines that no overcurrent will occur if at least two power storage units 12 are connected in parallel in this combination of connections.

[0036] In step S9, the ECU 14 transmits a control signal instructing the switch 26 to turn on to at least two power storage units 12 corresponding to the combination of connections based on the positive determination results in steps S5 to S8 via the communication line 28.

[0037] The BMU 32 of at least two power storage units 12 switches the switch 26 from off to on based on the control signal received by the communication unit 38. As a result, at least two power storage units 12 (batteries 30) are connected in parallel to the load 24. As a result, it is possible to supply power to the load 24 and perform charge and discharge between the power storage units 12 while suppressing the voltage difference between the power storage units 12 within the voltage threshold.

[0038] Also, in step S10, the ECU 14 notifies the user of the electric vehicle, etc. from the notification unit 16 that at least two power storage units 12 are connected.

[0039] Then, in step S11, when the above process is to be executed again (step S11: YES), the ECU 14 returns to step S1 or S2. Therefore, in the present embodiment, the processes from step S1 or S2 to step S11 can be repeatedly executed.

[0040] On the other hand, in steps S3 and S4, when a negative determination result is obtained (steps S3, S4: NO), the ECU 14 determines that only one power storage unit 12 can be used in the current state of the power device 10. Next, the ECU 14 proceeds to step S12 in FIG. 4 and determines whether or not the one power storage unit 12 is in a usable state.

[0041] When the one power storage unit 12 is in a usable state (step S12: YES), in the next step S13, the ECU 14 transmits a control signal instructing the communication unit 38 of the one power storage unit 12 to turn on the switch 26 via the communication line 28.

[0042] The BMU 32 of the one power storage unit 12 switches the switch 26 from off to on based on the control signal received by the communication unit 38. As a result, the one power storage unit 12 (battery 30) is connected to the load 24, and power is exchanged between the one power storage unit 12 and the load 24. Thereafter, the process of step S10 in FIG. 3 is executed, and the notification unit 16 notifies the outside that the one power storage unit 12 and the load 24 are connected.

[0043] On the other hand, in step S12, when the one power storage unit 12 is unusable (step S12: NO), the ECU 14 determines that there is no connectable power storage unit 12. In the next step S14, the ECU 14 decides to prohibit the connection of all the power storage units 12. Thereafter, the process of step S10 in FIG. 3 is executed, and the notification unit 16 notifies the outside that the connection of all the power storage units 12 is prohibited. Thereby, the user of the electric vehicle can be warned that the connection is prohibited.

[0044] Also, even when a negative determination result is obtained in steps S6 and S8 (steps S6, S8: NO), the ECU 14 determines that there is no connectable power storage unit 12, proceeds to step S14 in FIG. 4, and prohibits the connection of all the power storage units 12.

[0045] In the processes of FIGS. 3 and 4, the processes of steps S7 and S8 may be skipped. That is, in the processes of FIGS. 3 and 4, at least, based on the voltage difference, it is only necessary to determine the combination of connections of each power storage unit 12 and the prohibition of connection of each power storage unit 12.

[0046] [3. Specific Example of the Operation of this Embodiment] Next, a specific example of the above-described operation will be described with reference to FIG. 5. In this specific example, as shown in FIG. 5, when the voltage values of the first to fourth power storage units 12a to 12d (see FIGS. 1 and 2) are decreasing in order, by prohibiting the connection combinations with voltage differences exceeding the voltage threshold, the first to fourth power storage units 12a to 12d are connected with the connection combinations with voltage differences within the voltage threshold.

[0047] In the specific example, the voltage values of the first to fourth power storage units 12a to 12d before connection are V1 to V4, and the voltage threshold is Vthr. Also, in FIG. 5, the first to fourth power storage units 12a to 12d are denoted as NO.1 to NO.4.

[0048] As shown in FIG. 5, |V1 - V4| > Vthr (step S5 in FIG. 3: NO). Therefore, if the first to fourth power storage units 12a to 12d are connected in parallel to the load 24 (see FIGS. 1 and 2), there is a possibility that an overcurrent will flow (the connection of "NG" in FIG. 5). On the other hand, in the connection of the first to third power storage units 12a to 12c, the connection of the second to fourth power storage units 12b to 12d, the connection of the first power storage unit 12a and the second power storage unit 12b, the connection of the second power storage unit 12b and the third power storage unit 12c, and the connection of the third power storage unit 12c and the fourth power storage unit 12d, since the voltage values of the power storage units 12 to be connected are close to each other (adjacent), the voltage difference is within the voltage threshold Vthr, and no overcurrent is generated (the connection of "OK" in FIG. 5, step S6 in FIG. 3: YES).

[0049] Therefore, the ECU 14 alternatively selects any one combination of the "OK" connections in FIG. 5 (step S9 in FIG. 3). In this case, the ECU 14 transmits a control signal for turning on the switch 26 to the communication unit 38 of each power storage unit 12 to be connected via the communication line 28. As a result, the BMU 32 of each power storage unit 12 switches the switch 26 from off to on based on the control signal received by the communication unit 38. As a result, each power storage unit 12 is connected in parallel to the load 24, and charge and discharge are performed between the power storage units 12.

[0050] [4. Modified Example] The power device 10 according to the present embodiment may have the configuration of the modified example shown in FIG. 6. In this modified example, each power storage unit 12 (12a to 12d) has only the battery 30 and the temperature sensor 36. A voltage sensor 40 for sequentially detecting the voltage value of the battery 30 is connected in parallel to each battery 30. Further, the positive electrode terminal of each battery 30 is connected to the positive electrode terminal of the load 24 via the current sensor 42 and the switch 26. Furthermore, the negative electrode terminal of each battery 30 is connected to the negative electrode terminal of the load 24. The current sensor 42 sequentially detects the current value of the current flowing through the battery 30.

[0051] The ECU 14 is connected to each temperature sensor 36, each voltage sensor 40, and each current sensor 42 via the analog signal line 44. Therefore, the ECU 14 can sequentially acquire the temperature of the battery 30 detected by each temperature sensor 36, the voltage value of the battery 30 detected by each voltage sensor 40, and the current value detected by each current sensor 42 via the analog signal line 44 without using communication means such as the communication unit 38 (see FIG. 2). Therefore, also in this modified example, the ECU 14 can execute the connection process of the switch 26 and the like described above.

[0052] As described above, in the configurations of FIGS. 1 and 2, the ECU 14 acquires voltage values and the like from each power storage unit 12. Further, in the configuration of FIG. 6, the voltage value detected by the voltage sensor 40 is input to the ECU 14. In the present embodiment, without being limited to these configurations, the ECU 14 may estimate the voltage value based on information from each power storage unit 12 or the like.

[0053] [5. Effects of the Present Embodiment] As described above, the present embodiment relates to a power device 10 having a plurality of power storage units 12 (12a to 12d) and a control method thereof.

[0054] In this case, the power device 10 includes a voltage acquisition unit that acquires the voltage values of the plurality of power storage units 12 respectively, and an ECU 14 that functions as a connection control unit that prohibits the connection between the plurality of power storage units 12 where the voltage difference between the acquired voltage values of the plurality of power storage units 12 exceeds a voltage threshold (Vthr).

[0055] Further, the control method of the power device 10 includes a step (step S2 in FIG. 3) in which the ECU 14 acquires the voltage values of the plurality of power storage units 12 respectively, and a step (step S14 in FIG. 4) in which when the voltage difference between the acquired voltage values of the plurality of power storage units 12 exceeds the voltage threshold, the ECU 14 prohibits the connection between the plurality of power storage units 12 where the voltage difference exceeds the voltage threshold.

[0056] Thus, in the present embodiment, when the voltage difference between the voltage values of the plurality of power storage units 12 exceeds the voltage threshold, the connection between the plurality of power storage units 12 is prohibited. Thereby, the flow of a large current due to the voltage difference is avoided. As a result, the deterioration and failure of the power storage unit 12 can be prevented, and the long life of the power storage unit 12 can be realized.

[0057] In this case, the plurality of power storage units 12 can be connected to a load 24 (power utilization unit) that uses the power of the plurality of power storage units 12, and the ECU 14 prohibits the connection between the plurality of power storage units 12 and the load 24 when the voltage difference exceeds the voltage threshold. Thereby, the flow of a large current in the power device 10 is avoided, and the deterioration and failure of each power storage unit 12 and the load 24 can be prevented.

[0058] Also, when the voltage difference exceeds the voltage threshold, the ECU 14 permits the connection between one power storage unit 12 and the load 24 (step S13 in FIG. 4). Thereby, even when the voltage difference exceeds the voltage threshold, power can be supplied from one power storage unit 12 to the load 24.

[0059] Further, when there is a combination in which the voltage differences between a plurality of power storage units 12 do not exceed the voltage threshold, the ECU 14 permits the connection between the plurality of power storage units 12 whose voltage differences do not exceed the voltage threshold (step S6: YES and step S9 in FIG. 3). Thereby, it becomes possible to perform charge and discharge between the power storage units 12 so that the voltage difference does not exceed the voltage threshold.

[0060] Furthermore, the ECU 14 permits or prohibits the connection between a plurality of power storage units 12 accommodated in the power device 10 and available for use (steps S3 to S5 in FIG. 3). Thereby, the connection process of each power storage unit 12 can be efficiently performed.

[0061] The ECU 14 acquires the temperatures of the plurality of power storage units 12, and when the temperature difference between the acquired temperatures of the plurality of power storage units 12 exceeds the temperature threshold, prohibits the connection between the plurality of power storage units 12 whose temperature difference exceeds the temperature threshold (steps S7 and S8 in FIG. 3, step S14 in FIG. 4). The internal resistance changes due to the change in the temperature of the power storage unit 12, and the voltage value changes. Therefore, by prohibiting the connection between the plurality of power storage units 12 when the temperature difference exceeds the temperature threshold, it is possible to avoid the flow of a large current and surely prevent the deterioration and failure of the power storage unit 12.

[0062] The power device 10 further includes a plurality of switches 26 (connection parts) that connect the plurality of power storage parts 12 in parallel to a load 24 (power utilization part) that utilizes the power of the plurality of power storage parts 12. When the ECU 14 prohibits the connection between the plurality of power storage parts 12, the plurality of switches 26 cut off the connection between the plurality of power storage parts 12 and the load 24 (step S14 in FIG. 4). On the other hand, when the ECU 14 permits the connection between the plurality of power storage parts 12, the plurality of switches 26 connect the plurality of power storage parts 12 and the load 24 (step S9 in FIG. 3). Thereby, the connection between the plurality of power storage parts 12 and the load 24 by each switch 26 can be reliably controlled by the ECU 14.

[0063] The power device 10 further includes a notification part 16 that notifies the outside of the connection state of the plurality of power storage parts 12. Thereby, a user of the electric vehicle or the like can easily grasp the connection state.

[0064] Note that the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted based on the description content of this specification.

Claims

1. A power device (10) having a plurality of detachable power storage units (12, 12a to 12d) and an ECU (14), The ECU a voltage acquisition unit (14) that acquires voltage values ​​transmitted from the plurality of power storage units; a connection control unit (14) that, when a voltage difference between the voltage values ​​of the plurality of power storage units acquired by the voltage acquisition unit exceeds a voltage threshold (Vthr), prohibits connection between the plurality of power storage units whose voltage difference exceeds the voltage threshold; A power device having:

2. In the power device according to claim 1, The plurality of power storage units are connectable to a power utilization unit (24) that utilizes the power of the plurality of power storage units, The connection control unit prohibits connection between the plurality of power storage units and the power utilization unit when the voltage difference exceeds the voltage threshold.

3. In the power device according to claim 2, The connection control unit permits connection between one of the power storage units and the power utilization unit when the voltage difference exceeds the voltage threshold.

4. In the power device according to any one of claims 1 to 3, The connection control unit allows connection of the plurality of power storage units whose voltage difference does not exceed the voltage threshold when there is a combination of the plurality of power storage units whose voltage difference does not exceed the voltage threshold.

5. In the power device according to any one of claims 1 to 4, The power device, wherein the connection control unit permits or prohibits connection between a plurality of usable power storage units among the plurality of power storage units housed in the power device.

6. In the power device according to any one of claims 1 to 5, The power supply device further includes a temperature acquisition unit (14) that acquires temperatures of the plurality of power storage units, The connection control unit prohibits connection between multiple power storage units whose temperature difference exceeds the temperature threshold when the temperature difference between the multiple power storage units acquired by the temperature acquisition unit exceeds the temperature threshold.

7. In the power device according to any one of claims 1 to 6, The power consumption unit further includes a plurality of connection units (26) that connect the plurality of power storage units in parallel to a power consumption unit that utilizes the power of the plurality of power storage units, The plurality of connection units cut off the connection between the plurality of power storage units and the power utilization unit when the connection control unit prohibits the connection of the plurality of power storage units to each other, and connect the plurality of power storage units to the power utilization unit when the connection control unit allows the connection of the plurality of power storage units to each other.

8. In the power device according to any one of claims 1 to 7, The power device further comprises a notification unit (16) that notifies the outside of the connection states of the plurality of power storage units.

9. In the power device according to claim 8, the connection control unit permits connection of the plurality of power storage units when the voltage difference does not exceed the voltage threshold; The power device, wherein the notification unit notifies a user of the power device of information on the number of the plurality of power storage units that the connection control unit has permitted to be connected.

10. In the power device according to any one of claims 1 to 9, The ECU further includes a determination unit (14) that determines whether a plurality of the power storage units are housed in the power device.

11. In the power device according to any one of claims 1 to 10, Each of the plurality of power storage units is activated based on a voltage applied from the ECU.

12. In the power device according to any one of claims 1 to 11, When the difference between the maximum voltage and the minimum voltage among the voltage values ​​of the multiple storage units exceeds the voltage threshold, the connection control unit determines whether there is a combination of at least two storage units whose difference in voltage values ​​is within the voltage threshold, and if such a combination exists, allows connection of at least two of the storage units.

13. A control method for an electric power device (10) having a plurality of detachable power storage units (12, 12a to 12d) and an ECU (14), comprising: acquiring voltage values ​​transmitted from the plurality of power storage units by a voltage acquisition unit (14) of the ECU; When a voltage difference between the voltage values ​​of the plurality of power storage units acquired by the voltage acquisition unit exceeds a voltage threshold (Vthr), a connection control unit (14) of the ECU prohibits connection between the plurality of power storage units whose voltage difference exceeds the voltage threshold. A method for controlling a power device, comprising:

14. A program for causing a computer to execute the control method for the power device described in claim 13.

15. A computer-readable storage medium on which the program described in claim 14 is stored.

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