Power supply device and electric vehicle including the same

Abstract

To provide a technique capable of reducing a difference in residual capacity between a plurality of battery units.SOLUTION: A power supply device includes: a plurality of battery units; a connection circuit for selectively forming a series circuit for connecting the plurality of battery units in series to an electric load, and a parallel circuit for connecting the plurality of battery units in parallel to the electric load; and a control device for controlling the operation of the connection circuit. The control device can individually connect and disconnect each of the plurality of battery units to / from the electric load, in the parallel circuit. The control device is configured to control the connection circuit and form the parallel circuit when regenerative power is supplied to the plurality of battery units from the electric load.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a power supply device and an electric vehicle equipped with the same. [Background technology]

[0002] Patent Document 1 describes a power supply device. This power supply device includes a plurality of battery units, a connection circuit that selectively forms a series circuit that connects the plurality of battery units in series to an electrical load and a parallel circuit that connects the plurality of battery units in parallel to the electrical load, and a control device that controls the operation of the connection circuit. When regenerative power is supplied from the electrical load to the plurality of battery units, the control device controls the connection circuit to form a direct circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-099142 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power supply device such as that described in Patent Document 1, differences in remaining capacity occur among the multiple battery units due to manufacturing variations and variations in deterioration. When regenerative power is supplied to the multiple battery units, if the multiple battery units are connected in series, an increase in the differences in remaining capacity among the multiple battery units is suppressed. However, it is not possible to reduce the differences in remaining capacity among the multiple battery units.

[0005] This specification provides a technique that can reduce the remaining capacity difference between a plurality of battery units. [Means for solving the problem]

[0006] In a first aspect disclosed in the present specification, a power supply device may include a plurality of battery units, a connection circuit that selectively forms a series circuit that connects the plurality of battery units in series to an electrical load and a parallel circuit that connects the plurality of battery units in parallel to the electrical load, and a control device that controls operation of the connection circuit. The control device may be capable of individually connecting and disconnecting each of the plurality of battery units to the electrical load in the parallel circuit. The control device may be configured to control the connection circuit to form the parallel circuit when regenerative power is supplied from the electrical load to the plurality of battery units.

[0007] In the above configuration, power can be supplied to an electrical load by discharging the multiple battery units. Furthermore, the multiple battery units can be charged using regenerative power from the electrical load. In this case, if the multiple battery units are connected in series, all battery units are charged equally. That is, charging of all battery units starts and ends simultaneously. Therefore, even if there is a difference in remaining capacity among the multiple battery units, the difference in remaining capacity is not eliminated or reduced. In contrast, if the multiple battery units are connected in parallel, each of the multiple battery units can be individually connected and disconnected from the electrical load. As a result, when regenerative power is supplied from the electrical load, charging of a battery unit with a large remaining capacity can be prohibited while charging of a battery unit with a small remaining capacity can be performed. This reduces the difference in remaining capacity among the multiple battery units.

[0008] In a second aspect, in the first aspect, when the control device controls the connection circuit to form the parallel circuit, the control device may connect the battery unit having the smallest remaining capacity among the plurality of battery units to the electrical load preferentially.

[0009] According to the above configuration, the regenerative power supplied from the electrical load is preferentially supplied to the battery unit with the smallest remaining capacity, thereby enabling the difference in remaining capacity among the plurality of battery units to be reduced quickly.

[0010] In a third aspect, in the first or second aspect, the control device may control the connection circuit to form the series circuit when supplying power from the plurality of battery units to the electrical load.

[0011] According to the above configuration, it is possible to supply high voltage power from a plurality of battery units to an electrical load, compared to a configuration in which a parallel circuit is formed by a connection circuit.

[0012] In a fourth aspect, in any of the first to third aspects, the connection circuit may be provided with a circulating current prevention mechanism that prevents circulating current from flowing between the multiple battery units when the connection circuit forms the parallel circuit.

[0013] The circulating current flowing between the plurality of battery units can cause an abnormality in the connection circuit. With the above configuration, it is possible to prevent an abnormality from occurring in the connection circuit.

[0014] In a fifth aspect, an electric vehicle may include the power supply device of any one of the first to fourth aspects, an electric motor as the electrical load for driving wheels of the electric vehicle, and a charging port configured to allow an external charging device to be attached or detached and connected to the plurality of battery units via the connection circuit.

[0015] In an electric vehicle, battery units are frequently charged and discharged in response to acceleration and deceleration of the vehicle. Therefore, by employing a power supply device according to the present technology in an electric vehicle, differences in remaining capacity among multiple battery units can be eliminated frequently while the electric vehicle is traveling normally. This makes it possible to eliminate or reduce differences in remaining capacity among multiple battery units in advance before the multiple battery units are charged by an external charging device. Therefore, when charging by an external charging device, the multiple battery units can be easily charged to a fully charged state without requiring complex control. [Brief explanation of the drawings]

[0016] [Figure 1] The circuit diagram of electric vehicle 2 is shown. [Figure 2] 1 shows a circuit diagram of a first series circuit formed by a connection circuit 22. FIG. [Figure 3] 1 shows a circuit diagram of a first parallel circuit formed by the connection circuit 22. FIG. [Figure 4] 1 shows a circuit diagram of a first regeneration circuit formed by a connection circuit 22. [Figure 5] 1 shows a circuit diagram of a second regeneration circuit formed by the connection circuit 22. [Figure 6] 1 shows a circuit diagram of a second series circuit formed by the connection circuit 22. [Figure 7] 1 shows a circuit diagram of a second parallel circuit formed by the connection circuit 22. FIG. [Figure 8] 10 is a flowchart of a switching process executed by a control device 24. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] (Example) The electric vehicle 2 will be described with reference to Figures 1 to 7. The electric vehicle 2 may be an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a fuel cell vehicle, or the like.

[0018] As shown in Fig. 1, the electric vehicle 2 includes a power supply device 10, an electric motor 12, and a charging port 14. A charging plug of an external charging device is detachably connected to the charging port 14.

[0019] The power supply device 10 includes a plurality of battery units 20, a connection circuit 22, and a control device 24. The plurality of battery units 20 include a first battery unit 20A and a second battery unit 20B. The rated voltage of the first battery unit 20A and the second battery unit 20B is 400V. The electric motor 12 functions as an electric motor that drives the wheels of the electric vehicle 2 using power supplied from the plurality of battery units 20, and also functions as a generator that generates electricity using regenerative braking force, etc.

[0020] The connection circuit 22 includes a positive power supply line 30, a negative power supply line 32, a series line 34, a first parallel line 36, and a second parallel line 38. The positive power supply line 30 electrically connects the positive electrode of the first battery unit 20A to the electric motor 12. A first relay RL1 is provided in the positive power supply line 30. The negative power supply line 32 electrically connects the negative electrode of the second battery unit 20B to the electric motor 12. A second relay RL2 is provided in the negative power supply line 32. The series line 34 electrically connects the positive electrode of the second battery unit 20B to the negative electrode of the first battery unit 20A. A third relay RL3 is provided in the series line 34. The first parallel line 36 electrically connects the section of the positive power supply line 30 between the first battery unit 20A and the first relay RL1 and the section of the series line 34 between the second battery unit 20B and the third relay RL3. The first parallel line 36 is provided with a fourth relay RL4 and a first diode D1. The first diode D1 allows current to flow from the positive power supply line 30 to the series line 34 and prevents current from flowing from the series line 34 to the positive power supply line 30. The second parallel line 38 electrically connects the section of the negative power supply line 32 between the second battery unit 20B and the second relay RL2 and the section of the series line 34 between the first battery unit 20A and the third relay RL3. The second parallel line 38 is provided with a fifth relay RL5 and a second diode D2. The second diode D2 allows current to flow from the series line 34 to the negative power supply line 32 and prevents current from flowing from the negative power supply line 32 to the series line 34.

[0021] The connection circuit 22 further includes a positive electrode charging line 40 and a negative electrode charging line 42. The positive electrode charging line 40 electrically connects the section of the positive electrode power supply line 30 between the first relay RL1 and the electric motor 12 to the charging port 14. A sixth relay RL6 is provided in the positive electrode charging line 40. The negative electrode charging line 42 electrically connects the section of the negative electrode power supply line 32 between the second relay RL2 and the electric motor 12 to the charging port 14. A seventh relay RL7 is provided in the negative electrode charging line 42.

[0022] The control device 24 is a computer including a CPU. The control device 24 controls the operation of the first relay RL1 to the seventh relay RL7. By controlling the operation of the first relay RL1 to the seventh relay RL7, the control device 24 can form, in the connection circuit 22, a first series circuit (see FIG. 2) that connects the plurality of battery units 20 in series to the electric motor 12, a first parallel circuit (see FIG. 3) that connects the plurality of battery units 20 in parallel to the electric motor 12, a first regeneration circuit (see FIG. 4) that connects the first battery unit 20A to the electric motor 12, a second regeneration circuit (see FIG. 5) that connects the second battery unit 20B to the electric motor 12, a second series circuit (see FIG. 6) that connects the plurality of battery units 20 in series to the charging port 14, and a second parallel circuit (see FIG. 7) that connects the plurality of battery units 20 in parallel to the charging port 14.

[0023] 2 to 7, the following describes the first series circuit, first parallel circuit, first regeneration circuit, second regeneration circuit, second series circuit, and second parallel circuit formed by the connection circuit 22. In Fig. 2 to Fig. 7, for ease of understanding, paths through which current flows are indicated by bold lines.

[0024] 2, a first series circuit is formed by closing the first relay RL1 to the third relay RL3 and opening the fourth relay RL4 to the seventh relay RL7. When the electric motor 12 is in motor operation functioning as an electric motor, the control device 24 controls the connection circuit 22 to form the first series circuit. As an example, when the electric motor is in motor operation, the user operates the accelerator pedal of the electric vehicle 2.

[0025] 3, a first parallel circuit is formed by closing the first relay RL1, the second relay RL2, the fourth relay RL4, and the fifth relay RL5, and opening the third relay RL3, the sixth relay RL6, and the seventh relay RL7. The control device 24 controls the connection circuit 22 to form the first parallel circuit when the electric motor 12 is in a regenerative operation functioning as a prime mover. As an example, a regenerative operation occurs when the accelerator pedal of the electric vehicle 2 is not being operated by the user, but the brake pedal is being operated.

[0026] 4, a first regenerative circuit is formed by closing the first relay RL1, the second relay RL2, and the fourth relay RL4 and opening the third relay RL3 and the fifth relay RL5 to the seventh relay RL7. At the timing of switching from motor operation to regenerative operation, if the remaining capacity of the first battery unit 20A (hereinafter referred to as the "first battery remaining capacity") is smaller than the remaining capacity of the second battery unit 20B (hereinafter referred to as the "second battery remaining capacity"), the control device 24 controls the connection circuit 22 to form the first regenerative circuit.

[0027] 5, the second regenerative circuit is formed by closing the first relay RL1, the second relay RL2, and the fifth relay RL5 and opening the third relay RL3, the fourth relay RL4, the sixth relay RL6, and the seventh relay RL7. When the remaining charge of the second battery is smaller than the remaining charge of the first battery at the timing of switching from motor operation to regenerative operation, the control device 24 controls the connection circuit 22 to form the second regenerative circuit.

[0028] 6, a second series circuit is formed by closing the first relay RL1 to the third relay RL3, the sixth relay RL6, and the seventh relay RL7, and opening the fourth relay RL4 and the fifth relay RL5. When 800 V charging power is supplied from an external charging device, the control device 24 controls the connection circuit 22 to form the second series circuit.

[0029] 7, a second parallel circuit is formed by closing the first relay RL1, the second relay RL2, the fourth relay RL4 to the seventh relay RL7, and opening the third relay RL3. When 400V charging power is supplied from an external charging device, the control device 24 controls the connection circuit 22 to form a second series circuit.

[0030] In addition, when the first series circuit, the second series circuit, or the second parallel circuit is formed, the control device 24 is configured to stop supplying power to the multiple battery units 20 when the remaining capacity of one of the multiple battery units 20 reaches the full charge capacity.

[0031] Referring to FIG. 8, a description will be given of a switching process executed by the control device 24 when switching from motor operation to regenerative operation.

[0032] In S10, the control device 24 determines whether the first battery remaining capacity and the second battery remaining capacity are the same. If the first battery remaining capacity and the second battery remaining capacity are the same (YES in S10), the control device 24 proceeds to S12. Note that the first battery remaining capacity and the second battery remaining capacity being the same includes not only a case where the first battery remaining capacity and the second battery remaining capacity are completely the same, but also a case where they are slightly different. On the other hand, if the first battery remaining capacity and the second battery remaining capacity are not the same (NO in S10), the control device 24 proceeds to S20.

[0033] In S12, the control device 24 controls the connection circuit 22 to form the first parallel circuit (see FIG. 3). When S12 ends, the control device 24 ends the process of FIG. 8. As described above, even after a determination of YES is made in S10, the first battery remaining capacity and the second battery remaining capacity may be slightly different. For example, if the first parallel circuit is formed when the second battery remaining capacity is slightly lower than the first battery remaining capacity, a circulating current may flow from the first battery unit 20A to the second battery unit 20B without passing through the electric motor 12. In this situation, if the third relay RL3 and the fourth relay RL4 are opened, an arc may occur in the third relay RL3 and the fourth relay RL4. In this regard, in this embodiment, the second diode D2 prohibits current from flowing from the negative power supply line 32 to the series line 34. This prevents the circulating current from flowing. Therefore, an arc may be prevented from occurring in the third relay RL3 and the fourth relay RL4.

[0034] In addition, in S20, the control device 24 determines whether the first battery remaining capacity exceeds the second battery remaining capacity. If the first battery remaining capacity exceeds the second battery remaining capacity (YES in S20), the control device 24 proceeds to S22. On the other hand, if the first battery remaining capacity does not exceed the second battery remaining capacity (NO in S20), the control device 24 proceeds to S30.

[0035] In S22, the control device 24 controls the connection circuit 22 to form a second regeneration circuit (see FIG. 5). This causes regenerative power to be supplied only to the second battery unit 20B. As a result, the difference in remaining capacity between the first battery remaining capacity and the second battery remaining capacity decreases.

[0036] In S24, the control device 24 determines whether the first battery remaining capacity and the second battery remaining capacity are the same. If the first battery remaining capacity and the second battery remaining capacity are the same (YES in S24), the control device 24 proceeds to S12. On the other hand, if the first battery remaining capacity and the second battery remaining capacity are not the same (NO in S24), the control device 24 returns to S20. Although not shown in the figure, the control device 24 executes the process of S24 when a predetermined time has elapsed since the end of S22 or S30.

[0037] Furthermore, in S30, the control device 24 controls the connection circuit 22 to form a first regeneration circuit (see FIG. 4). This causes regenerative power to be supplied only to the first battery unit 20A. As a result, the difference in capacity between the first battery remaining capacity and the second battery remaining capacity decreases. When S30 ends, the control device 24 proceeds to S24.

[0038] As described above, in the switching process of FIG. 8, when switching from motor operation to regenerative operation, the control device 24 connects the battery unit with the smallest remaining capacity to the electric motor 12 first. Note that after determining YES in S10 or YES in S24, there may be a slight difference in remaining capacity among the multiple battery units 20. When the first parallel circuit is formed by the connection circuit 22, the supply of regenerative power to the battery unit with the smallest remaining capacity continues even if the remaining capacity of the battery unit with the large remaining capacity reaches the full charge capacity. Therefore, the remaining capacity of the battery unit with the smallest remaining capacity also approaches the full charge capacity. This makes it possible to further reduce the difference in remaining capacity among the multiple battery units 20.

[0039] As described above, the power supply device 10 includes a plurality of battery units 20, a connection circuit 22 that selectively forms a first series circuit (an example of a "series circuit") that connects the plurality of battery units 20 in series to the electric motor 12 (an example of an "electrical load"), and a first parallel circuit (an example of a "parallel circuit") that connects the plurality of battery units 20 in parallel to the electric motor 12, and a control device 24 that controls the operation of the connection circuit 22. The control device 24 can individually connect and disconnect each of the plurality of battery units 20 to and from the electric motor 12 in the first parallel circuit. The control device 24 is configured to control the connection circuit 22 to form the first parallel circuit when regenerative power is supplied from the electric motor 12 to the plurality of battery units 20.

[0040] According to the above configuration, when regenerative power is supplied from the electric motor 12 to the plurality of battery units 20, the control device 24 controls the connection circuit 22 to form a first parallel circuit. When the plurality of battery units 20 are connected in parallel, it becomes possible to individually connect and disconnect each of the plurality of battery units 20 to and from the electric motor 12. As a result, when regenerative power is supplied from the electric motor 12, it is possible to charge the battery unit with the smallest remaining capacity while prohibiting charging of the battery unit with the largest remaining capacity. This makes it possible to reduce the difference in remaining capacity among the plurality of battery units 20.

[0041] Furthermore, as shown in FIG. 8, when the control device 24 controls the connection circuit 22 to form the first parallel circuit, the control device 24 connects the battery unit with the smallest remaining capacity to the electric motor 12 first among the plurality of battery units 20.

[0042] According to the above configuration, the regenerative power supplied from the electric motor 12 is preferentially supplied to the battery unit with the smallest remaining capacity. Therefore, the remaining capacity difference between the plurality of battery units 20 can be reduced quickly.

[0043] Furthermore, as shown in FIG. 2, when power is supplied from a plurality of battery units 20 to the electric motor 12, the control device 24 controls the connection circuit 22 to form a first series circuit.

[0044] According to the above configuration, higher voltage power can be supplied from the plurality of battery units 20 to the electric motor 12, compared to a configuration in which the first parallel circuit is formed by the connection circuit 22.

[0045] As shown in FIG. 1, the connection circuit 22 is provided with a second diode D2 (an example of a "circulating current prevention mechanism") that prevents circulating current from flowing between the multiple battery units when the connection circuit 22 forms a first parallel circuit.

[0046] A circulating current flowing between the plurality of battery units 20 may cause an abnormality in the connection circuit 22. With the above configuration, the occurrence of an abnormality in the connection circuit 22 can be suppressed.

[0047] As shown in FIG. 1, the electric vehicle 2 includes a power supply device 10, an electric motor 12, and a charging port 14 that is configured to allow an external charging device to be attached or detached and is connected to a plurality of battery units 20 via a connection circuit 22.

[0048] In an electric vehicle 2, the battery units are frequently charged and discharged in response to the acceleration and deceleration of the electric vehicle 2. Therefore, by employing the power supply device 10 according to the present technology in the electric vehicle 2, the remaining capacity differences among the plurality of battery units 20 are frequently eliminated while the electric vehicle 2 is traveling normally. This makes it possible to eliminate or reduce the remaining capacity differences among the plurality of battery units 20 in advance before the plurality of battery units 20 are charged by an external charging device. Therefore, when charging by an external charging device, the plurality of battery units 20 can be easily charged to a fully charged state without requiring complex control.

[0049] Furthermore, in the electric vehicle 2, when the remaining capacity of one of the multiple battery units 20 reaches zero, the supply of power from the multiple battery units 20 to the electric motor 12 may be stopped even if the remaining capacity of the other battery units is not zero. With the above configuration, the difference in remaining capacity among the multiple battery units 20 is relatively small, so when the remaining capacity of one battery unit reaches zero, the remaining capacity of the other battery unit is close to zero. Therefore, the multiple battery units 20 can be used effectively.

[0050] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Modifications of the above examples are listed below.

[0051] (First Modification) The number of the plurality of battery units is not limited to two, but may be three or more.

[0052] (Second Variation) S10 and S20 to S30 in FIG. 8 can be omitted.

[0053] (Third Modification) When power is supplied from a plurality of battery units 20 to the electric motor 12, the control device 24 may control the connection circuit 22 to form a first parallel circuit.

[0054] (Fourth Modification) The connection circuit 22 does not have to include the first diode D1 and the second diode D2.

[0055] (Fifth Modification) The connection circuit 22 may include a switch mechanism or the like for switching the electrical connection of each line, instead of the first relay RL1 to the seventh relay RL7.

[0056] The technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful. [Explanation of symbols]

[0057] 2: electric vehicle, 10: power supply unit, 12: electric motor, 14: charging port, 20: battery unit, 20A: first battery unit, 20B: second battery unit, 22: connection circuit, 24: control device, 30: positive power supply line, 32: negative power supply line, 34: series line, 36: first parallel line, 38: second parallel line, 40: positive charging line, 42: negative charging line, D1: first diode, D2: second diode, RL1: first relay, RL2: second relay, RL3: third relay, RL4: fourth relay, RL5: fifth relay, RL6: sixth relay, RL7: seventh relay

Claims

1. 1. A power supply device, comprising: a plurality of battery units; a connection circuit that selectively forms a series circuit that connects the plurality of battery units in series to an electrical load and a parallel circuit that connects the plurality of battery units in parallel to the electrical load; a control device for controlling the operation of the connection circuit, the control device is capable of individually connecting and disconnecting each of the plurality of battery units to and from the electrical load in the parallel circuit; the control device is configured to control the connection circuit to form the parallel circuit when regenerative power is supplied from the electrical load to the plurality of battery units. power supply.

2. 2. The power supply device according to claim 1, wherein, when the control device controls the connection circuit to form the parallel circuit, the control device connects the battery unit having the smallest remaining capacity to the electrical load first among the plurality of battery units.

3. The power supply device according to claim 2 , wherein the control device controls the connection circuit to form the series circuit when power is supplied from the plurality of battery units to the electrical load.

4. 2. The power supply device according to claim 1, wherein the connection circuit is provided with a circulating current prevention mechanism that prevents a circulating current from flowing between the plurality of battery units when the connection circuit forms the parallel circuit.

5. An electric vehicle, The power supply device according to any one of claims 1 to 4; an electric motor that drives wheels of the electric vehicle as the electric load; a charging port configured to allow an external charging device to be attached / detached and connected to the plurality of battery units via the connection circuit; An electric vehicle equipped with:

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