Power supply device

Abstract

The present invention is a power supply device comprising: wiring on a high-potential side and a low-potential side, wherein a plurality of batteries are connected in parallel; a plurality of switching means, which individually switch the continuity of the wiring to the plurality of batteries; and a control means, which controls the plurality of switching means; wherein the control means performs connection switching control to sequentially switch the batteries connected to one of the plurality of batteries to the wiring within a unit time.

Description

[Technical Field]

[0001] This invention relates to a power supply device. [Previous Technology]

[0002] The proposal includes a power supply device that can connect multiple battery packs in parallel. On the other hand, connecting multiple battery packs with large voltage differences in parallel can cause unexpected phenomena such as current flow between the battery packs. Patent Document 1 discloses a device that can use the power of any one battery pack when the voltage difference between two battery packs is large. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Chinese Patent Publication No. 110682828A Specification [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] In the device of Patent Document 1, the power consumption of a particular battery pack increases, which may lead to its deterioration or an increase in the frequency of charging or exchanging.

[0006] The object of this invention is to provide a power supply device that efficiently uses a plurality of batteries. [Means for solving the problem]

[0007] According to the present invention, a power supply device is provided, comprising: wiring on a high-potential side and a low-potential side, wherein a plurality of batteries are connected in parallel; a plurality of switching means, which individually switch the intermittent connection of the aforementioned wiring to the aforementioned plurality of batteries; and a control means, which controls the aforementioned plurality of switching means; wherein the aforementioned control means performs connection switching control, within a unit time, sequentially switching the connection of one of the aforementioned plurality of batteries connected to the aforementioned wiring. [Effects of the Invention]

[0008] According to the present invention, a power supply device that can efficiently use a plurality of batteries with easy control can be provided.

Implementation Method

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Furthermore, the following embodiments are not limited to the invention related to the claims, nor are they limited to the requirement that all combinations of features described in the embodiments are necessary for the invention. Two or more features may be arbitrarily combined among the plurality of features described in the embodiments. Moreover, the same or identical configurations are assigned the same reference numerals, and repeated descriptions are omitted.

[0011] Figure 1 is a block diagram of a power supply device 1 according to one embodiment of the present invention. The power supply device 1 is a device that uses a DC power source, namely a plurality of batteries 2A and 2B (generally referred to as batteries 2 or without distinction), to supply power to a load. In this embodiment, the load is a motor 3, and the power supply device 1 also functions as a drive device for driving the motor 3. For example, it can be used as a drive device for driving a vehicle motor. However, the present invention can be applied to power supply devices that supply power to various loads, and can also be used in stationary power supplies, mobile power supplies, etc.

[0012] In this embodiment, each battery 2 is a removable battery, in particular, a portable battery pack that can be attached to and removed from the power supply device 1. However, each battery 2 may also be fixedly mounted on the power supply device 1, and some of the batteries may be portable battery packs while the remaining batteries are fixedly mounted on the power supply device 1.

[0013] Each battery 2 includes: an energy storage unit 2a and a BMU (management system) 2b for managing the energy storage unit 2a. The energy storage unit 2a stores the power output from the battery 2, for example, it is configured by connecting a plurality of battery cells in series. The battery cells are, for example, lithium-ion battery cells.

[0014] BMU2b includes: a processor for controlling the charging and discharging of the energy storage unit 2a; a memory device such as a semiconductor memory storing the program executed by the processor or information related to the state of the energy storage unit 2a; an input / output interface; and a communication interface for communicating with the control circuit 19 described later. Furthermore, BMU2b includes: a detection circuit for detecting the remaining charge of the energy storage unit 2a, the charging / discharging current, and the charging / discharging voltage; the processor controls the upper limit of the discharge power and the charging amount of the battery 2 based on the detection results of the detection circuit. For example, if the discharge power of the battery 2 reaches the upper limit, the processor controls the discharge of the energy storage unit 2a to maintain the discharge power of the battery 2 at the upper limit value.

[0015] In this embodiment, the motor 3 is an AC motor, for example, a three-phase brushless motor. The power supply unit 1 converts the DC voltage output from the battery 2 into AC voltage to drive the motor 3.

[0016] The power supply device 1 includes terminals 10a, 10b, and 10c electrically connected to battery 2A, and terminals 11a, 11b, and 11c electrically connected to battery 2B. The positive terminal of battery 2 is connected to terminals 10a and 11a, and the negative terminal of battery 2 is connected to terminals 10b and 11b. The communication terminals of the BMU2b of battery 2 are connected to terminals 10c and 11c.

[0017] The power supply device 1 includes a DC wiring 12 on the high-potential side and a DC wiring 13 on the low-potential side. The potential difference (voltage) between DC wiring 12 and DC wiring 13 is called the output voltage Vout. The power supply device 1 also includes a plurality of switching elements SW1 and SW2. DC wiring 12 is connected to terminal 10a through switching element SW1 and to terminal 11a through switching element SW2. DC wiring 13 is connected to terminals 10b and 11b. With this configuration, a plurality of batteries 2A and 2B are connected in parallel to DC wiring 12 and 13.

[0018] Switching elements SW1 and SW2 are, for example, transistors, which individually switch the continuity of the plurality of batteries 2A and 2B on DC wirings 12 and 13 via control signals from control circuit 19. In this embodiment, switching element SW1 connects the positive terminal of battery 2A to DC wiring 12 by being on, and disconnects the positive terminal of battery 2A from DC wiring 12 by being off. Switching element SW2 connects the positive terminal of battery 2B to DC wiring 12 by being on, and disconnects the positive terminal of battery 2B from DC wiring 12 by being off.

[0019] A diode 15 is provided between DC wiring 12 and DC wiring 13 to limit the current flow from DC wiring 13 to DC wiring 12. Furthermore, the power supply device 1 includes a smoothing circuit 14 that smooths the output voltage Vout of DC wirings 12 and 13. In this embodiment, the smoothing circuit 14 is an LC filter circuit, which includes an inductor 14a connected in series with DC wiring 12 and a capacitor 14b connected between DC wiring 12 and DC wiring 13.

[0020] The power supply unit 1 includes an inverter 17. An output voltage Vout is input to the inverter 17; the inverter 17 converts the DC voltage, i.e., the output voltage Vout, into an AC voltage and outputs it from the three-phase terminals 18 to the motor 3. The inverter 17 includes, for example, an H-bridge circuit with four FETs (field-effect transistors) and a control circuit that sequentially switches the conduction and disconnection of each FET, converting the output voltage Vout into a single-phase AC voltage. The voltage detection circuit 16 detects the output voltage Vout input to the inverter 17.

[0021] The power supply device 1 includes a control circuit 19. The control circuit 19 includes, for example, a memory device such as a processor and semiconductor memory, an input / output interface, and a communication interface. The memory device stores programs executed by the processor or data used by the processor for processing.

[0022] The control circuit 19 is connected via terminals 10c and 11c to communicate with the BMU2b of each battery 2, and can obtain output capability information from the BMU2b. The so-called output capability information is the status information of the battery 2 regarding its current ability to output power, such as residual capacity information (SOC: remaining power / fully charged capacity × 100), voltage information (each output voltage V1, V2), etc.

[0023] Furthermore, the control circuit 19 can also be connected to communicate with the control circuit of the inverter 17. Moreover, the control circuit 19 is connected to the voltage detection circuit 16 and can obtain its detection results from the voltage detection circuit 16.

[0024] <Battery Connection Control> The control circuit 19 switches the connection modes of batteries 2A and 2B to DC wirings 12 and 13 by controlling the switching elements SW1 and SW2 to turn them on and off. When both batteries 2A and 2B are connected to DC wirings 12 and 13, the power supplied to the inverter 17 is at its maximum. However, when the difference in output voltage between batteries 2A and 2B is large, current flows from one battery to the other. In this embodiment, because batteries 2A and 2B are interchangeable mobile battery packs, a large difference in their output voltages is likely to occur. In such cases, it is possible to consider the possibility that only one battery is continuously connected to DC wirings 12 and 13; however, the power consumption of that battery increases, potentially leading to its degradation, or an increase in the frequency of charging or swapping.

[0025] In this embodiment, the control circuit 19 executes a connection switching control to alternately connect batteries 2A and 2B to DC wirings 12 and 13, thereby efficiently utilizing a plurality of batteries 2A and 2B. Figure 2 is an explanatory diagram of this. In Figure 2, t represents the elapsed time, and T represents a unit time. In the connection switching control, a unit time T is taken as one cycle, and within a unit time T, the batteries connected to one of DC wirings 12 and 13 of batteries 2A and 2B are repeatedly and sequentially switched. The unit time T is, for example, a time in the range of 50 μs to 1 ms. V1 represents the output voltage of battery 2A, and V2 represents the output voltage of battery 2B. In the example shown, V1 > V2.

[0026] The output voltage Vout becomes output voltage V1 when switching element SW1 is on and switching element SW2 is off, and becomes output voltage V2 when switching element SW2 is on and switching element SW1 is off. Then, the output voltage Vout becomes the voltage V averaged over a unit time T.

[0027] In the example of Figure 2, the on-time of switching element SW1 (connection time of battery 2A) and the on-time of switching element SW2 (connection time of battery 2B) in unit time T are T / 2 respectively. If the ratio of on-time to off-time in unit time T is expressed as the duty cycle, the duty cycle of switching element SW1 is 50%, and the duty cycle of switching element SW2 is also 50%. The average voltage of the output voltage Vout is V = 1 / 2 × (V1 + V2). The temporal waveform of the output voltage Vout becomes a signal that alternately repeats between V1 and V2. Even when the difference between V1 and V2 is large, because a smoothing circuit 14 is provided in this embodiment, the output voltage Vout is smoothed by the smoothing circuit 14 before being input to the inverter 17.

[0028] Assuming V1=60V, V2=40V, and the current consumption is 100A, the output voltage of inverter 17 is V=50V, and the output power is W=5kW. In this case, the average power output from battery 2A is 3kW, and the average power output from battery 2B is 2kW.

[0029] Control circuit 19 can change the connection time of batteries 2A and 2B to DC wirings 12 and 13, that is, it can change the duty cycle. Figure 3 shows an example with a changed duty cycle. In the illustrated example, the duty cycle of switching element SW1 is 20%, and the duty cycle of switching element SW2 is 80%. The average voltage of the output voltage Vout is V = 1 / 5 × V1 + 4 / 5 × V2.

[0030] Figure 4 shows the relationship between the operating ratio of the switching element SW1 and the power ratio of battery 2A and battery 2B when V1 > V2 (Figure G1), the relationship between the output voltage (Figure G2), the relationship between the output power W1-max of battery 2A (Figure G3), the relationship between the output power W2-max of battery 2B (Figure G4), and the relationship between the output power of inverter 17 (Figure G5).

[0031] The duty ratio in Figure 4 represents the duty ratio of switching element SW1. Therefore, when the duty ratio is 0%, the duty ratio of switching element SW2 is 100%. Conversely, when the duty ratio is 100%, the duty ratio of switching element SW2 is 0%. The horizontal axis of charts G1 to G5 all represent the duty ratio of switching element SW1.

[0032] In Figure G1, if the current consumption of either battery 2A or 2B connected to DC wiring 12 and 13 is temporarily set to be the same, the ratio of the power output from battery 2A to battery 2B becomes 50%, as shown in Figure G1, which is a working ratio lower than 50%.

[0033] In chart G2, when the duty cycle is 0%, the output voltage (Vout) is the output voltage V2 of battery 2B, and when the duty cycle is 100%, the output voltage (Vout) is the output voltage V1 (G2) of battery 2A. The output voltage changes due to the duty cycle.

[0034] Chart G3 represents the output power W1-max of battery 2A per unit time T. As the duty cycle increases from 0%, the output power W1-max increases. At a duty cycle of 50%, the upper limit of the discharge power of battery 2A (e.g., the upper limit of the discharge current) is reached, and the output is limited by the BMU2b of battery 2A. After that, even if the duty cycle increases, the output power W1-max does not increase.

[0035] Chart G4 represents the output power W2-max of battery 2B per unit time T. Observing the direction of the decrease in duty cycle from 100%, the duty cycle of switching element SW2 increases from 0%, so the output power W2-max increases. When the duty cycle is 50%, the upper limit of the discharge power of battery 2B (e.g., the upper limit of the discharge current) is reached, and the output is limited by BMU2b of battery 2B. After that, even if the duty cycle decreases (the duty cycle of switching element SW2 increases), the output power W2-max does not increase.

[0036] Chart G5 represents the output power W-max of inverter 17 per unit time T, which is the total output power W1-max and W2-max of batteries 2A and 2B respectively. The output power W-max is maximum at a duty cycle of 50%, and tends to decrease as the duty cycle increases or decreases. By controlling the duty cycle and limiting the discharge power of battery 2 caused by BMU2b, protection of battery 2 can be achieved, and the output voltage Vout and output power W-max can be controlled.

[0037] <Processing Example> This section describes a processing example executed by the processor of the control circuit 19. Figure 5 is a flowchart showing the control configuration of the selection switching elements SW1 and SW2. The processor of the control circuit 19 periodically executes the same processing as shown in Figure 5. In S1, voltage information (output voltages V1 and V2) of batteries 2A and 2B is obtained from each BMU2b of batteries 2A and 2B via communication. In S2, the voltage difference between the output voltages (V1 and V2) obtained in S1 is calculated. In S3, it is determined whether the voltage difference (=|V1-V2|) calculated in S2 exceeds a threshold. The threshold is, for example, a value within the range of 1.5V, or a value of 1% to 3% of the average value of the output voltages (V1 and V2).

[0038] If the voltage difference calculated in S2 exceeds the threshold, proceed to S4; otherwise, proceed to S5. In S4, execute the connection switching control described above, and alternately connect batteries 2A and 2B to DC wiring lines 12 and 13. In S5, execute simultaneous connection control, and connect batteries 2A and 2B together to DC wiring lines 12 and 13.

[0039] Under the simultaneous connection control in S5, switching elements SW1 and SW2 are controlled to be turned on together. This allows for the supply of more power to the load motor 3 than under connection switching control. Under the connection switching control in S4, current flow between batteries 2A and 2B is prevented, and these batteries 2 can be used efficiently.

[0040] Figure 6 is a flowchart illustrating an example of drive control of switching elements SW1 and SW2 when connection switching control S4 is selected, executed periodically with a shorter cycle than that in Figure 5. In S11, the output voltage Vout is detected from the voltage detection circuit 16. In S12, the difference between the output voltage Vout obtained in S11 and the target output voltage is calculated. In S13, voltage information (output voltages V1 and V2) of batteries 2A and 2B is obtained via communication from each BMU2b of batteries 2A and 2B. In S14, based on the difference calculated in S12 and the voltage information obtained in S13, the operating ratio of each switching element SW1 and SW2 is set to reduce the difference calculated in S12. The operating ratio is set in the range of 0% < operating ratio < 100%. In S15, the switching of switching elements SW1 and SW2 is executed using the operating ratio set in S14. Through the above processing, the output voltage Vout can be maintained at the target output voltage.

[0041] <Other Embodiments> In the above embodiment, switching elements SW1 and SW2 are provided on the DC wiring 12 on the high potential side; however, they may also be provided on the DC wiring 13 on the low potential side. Figure 7 shows one example. In the illustrated example, both switching elements SW1 and SW2 are provided on the DC wiring 13. Furthermore, it is also possible to provide a portion of the switching elements on the DC wiring 12 and the remaining switching elements on the DC wiring 13.

[0042] Next, in the above embodiment, the control mode (S1~S3) of switching elements SW1 and SW2 is selected based on the voltage information obtained from BMU2b. However, the control mode can also be selected based on output capability information other than voltage information. For example, connection switching control can be performed when the difference in SOC between battery 2A and battery 2B exceeds a certain value, and simultaneous connection control can be performed when the difference is below the certain value.

[0043] Next, in the above embodiment, two batteries 2 were used; however, three or more batteries 2 can be used. Figure 8 is a block diagram showing a power supply device 1A that can connect four batteries 2A to 2D. The configuration of the power supply device 1A is the same as that in Figure 1, and switching elements SW1 to SW4 are provided for each battery 2A to 2D, which can individually switch the continuity between the batteries 2A to 2D and the DC wiring 12 and 13. Figure 9 is an explanatory diagram of the connection switching control in the configuration example of Figure 8. In the illustrated example, the operating ratio of each of the switching elements SW1 to SW4 is 25%.

[0044] Next, the power supply device 1 in FIG1 includes an inverter 17 and is configured to output AC power, but it may also be configured to not include an inverter 17 and directly supply the output voltage Vout to an external load.

[0045] Next, an example of selecting simultaneous connection control in the process shown in Figure 5, where the voltage difference is below a threshold in S3 (S5), will be explained. The conditions for selecting simultaneous connection control can include not only the condition that the voltage difference is below the threshold, but also other conditions. For example, a load demanding power exceeding a predetermined threshold may be considered. Even if other conditions are not met, connection switching control can still be selected when the voltage difference is below the threshold.

[0046] <Summary of Embodiments> The above embodiments disclose at least the following power supply devices.

[0047] 1. The power supply device (1, 1A) of the above embodiment includes: wiring (12, 13) on a high-potential side and a low-potential side, which connects a plurality of batteries (2) in parallel; a plurality of switching means (SW) that individually switch the continuity of the aforementioned wiring to the aforementioned plurality of batteries; and a control means (19) that controls the aforementioned plurality of switching means; wherein, the aforementioned control means performs connection switching control (S4) to sequentially switch the battery connected to one of the aforementioned plurality of batteries to the aforementioned wiring within a unit time. According to this embodiment, a power supply device that can efficiently use a plurality of batteries with easy control can be provided.

[0048] 2. In the above embodiment, in the aforementioned connection switching control, the connection time of each battery in the aforementioned wiring within the aforementioned unit time can be changed (S14). According to this embodiment, the DC output voltage can be controlled.

[0049] 3. The power supply device of the above embodiment includes: a detection means (16) for detecting the output voltage of the aforementioned wiring; and a control means for changing the connection time of each battery in the aforementioned wiring within the aforementioned unit time period (S11, S14) based on the detection result of the aforementioned detection means during the aforementioned connection switching control. According to this embodiment, the DC output voltage can be controlled in conjunction with the target voltage.

[0050] 4. In the above embodiment, the aforementioned control means determines whether to execute the aforementioned connection switching control (S3) based on the output capability information of each of the aforementioned plurality of batteries. According to this embodiment, the aforementioned connection switching control is executed when there is a difference in output capability between the aforementioned batteries, thereby maximizing the utilization of the aforementioned batteries.

[0051] 5. In the above embodiment, the aforementioned control means executes the aforementioned connection switching control (S3, S4) when the output voltage difference between the aforementioned plurality of batteries exceeds a predetermined value. According to this embodiment, by executing the aforementioned connection switching control when there is a risk of current flow between the aforementioned batteries, the problem can be prevented and the aforementioned batteries can be utilized.

[0052] 6. In the above embodiment, the aforementioned control means performs control (S3, S5) to simultaneously connect the aforementioned plurality of batteries to the aforementioned wiring, taking as a condition that the output voltage difference between the aforementioned plurality of batteries is below a certain value. According to this embodiment, a larger amount of power can be supplied to the load.

[0053] 7. The power supply device of the above embodiment includes: a smoothing circuit (S14) that smooths the output voltage of the aforementioned wiring. According to this embodiment, even if the battery connected to one of the aforementioned wirings is switched sequentially, an averaged and stable voltage can be output.

[0054] 8. In the above embodiment, the aforementioned plurality of batteries are mobile battery packs equipped with a management system (2b); the aforementioned control means can communicate with the aforementioned management system. According to this embodiment, information related to the state of the aforementioned mobile battery packs can be obtained from the aforementioned management system.

[0055] 9. In the above embodiment, the aforementioned management system controls the upper limit of the discharge power of the aforementioned battery. According to this embodiment, the protection of the aforementioned battery can be achieved, and multiple batteries can be used efficiently.

[0056] 10. The power supply device of the above embodiment includes: an inverter (17) that converts the output voltage (Vout) of the aforementioned wiring into an AC voltage. According to this embodiment, power can be provided to loads that consume AC power.

[0057] 11. In the above embodiment, at least one of the aforementioned plurality of batteries is a removable battery. According to this embodiment, removable batteries with different usage conditions or deterioration conditions can be effectively used.

[0058] The above describes the embodiments of the invention. However, the invention is not limited to the embodiments described above. Various modifications and alterations can be made within the scope of the spirit of the invention. [Simplified Explanation of the Diagram]

[0009] [Figure 1] is a block diagram of a power supply device according to an embodiment of the present invention. [Figure 2] is a timing flowchart showing the relationship between the on / off timing of each switching element and the output voltage. [Figure 3] is a timing flowchart showing the relationship between the on / off timing of each switching element and the output voltage. [Figure 4] is a graph showing the changes in connection time ratio, power ratio, output voltage, individual output power, and total output power. [Figure 5] is a flowchart showing an example of processing performed by the control circuit. [Figure 6] is a flowchart showing an example of processing performed by the control circuit. [Figure 7] is a block diagram showing a modified example of the power supply device of Figure 1. [Figure 8] is a block diagram showing an example of another power supply device with a different number of batteries. [Figure 9] is a timing flowchart showing the on / off timing of each switching element in the example of Figure 8.

Claims

1. A power supply device comprising: wiring on a high-potential side and a low-potential side, wherein a plurality of batteries are connected in parallel; a plurality of switching means for individually switching the continuity of the wiring with respect to the plurality of batteries; and a control means for controlling the plurality of switching means; wherein, The aforementioned control method is a connection switching control that sequentially switches the connection of one of the aforementioned batteries to the aforementioned wiring within a unit of time.

2. The power supply device as requested in item 1, wherein, In the aforementioned connection switching control, the connection time of each battery in the aforementioned wiring within the aforementioned unit time period can be changed.

3. The power supply device as claimed in claim 1, wherein, It includes: a detection means for detecting the output voltage of the aforementioned wiring; and a control means, which, in the aforementioned connection switching control, changes the connection time of each battery in the aforementioned wiring within the aforementioned unit time based on the detection result of the aforementioned detection means.

4. A power supply device as described in any of claims 1 to 3, wherein, The aforementioned control method determines whether to execute the aforementioned connection switching control based on the output capability information of each of the aforementioned plurality of batteries.

5. A power supply device as described in any of claims 1 to 3, wherein, The aforementioned control method is to execute the aforementioned connection switching control when the output voltage difference between the aforementioned plurality of batteries exceeds a certain value.

6. A power supply device as described in any of claims 1 to 3, wherein, The aforementioned control method uses the condition that the output voltage difference between the aforementioned plurality of batteries is below a certain value as a condition to execute control that simultaneously connects the aforementioned plurality of batteries to the aforementioned wiring.

7. The power supply device as claimed in claim 1, wherein, It also features: a smoothing circuit, which smooths the output voltage of the aforementioned wiring.

8. The power supply device as claimed in claim 1, wherein, The aforementioned plurality of batteries are mobile battery packs equipped with a management system; the aforementioned control means can communicate with the aforementioned management system.

9. The power supply device as requested in item 8, wherein, The aforementioned management system controls the upper limit of the discharge power of the aforementioned battery.

10. The power supply device as claimed in claim 1, wherein, It also includes: an inverter, which converts the output voltage of the aforementioned wiring into AC voltage.

11. The power supply device as claimed in claim 1, wherein, At least one of the aforementioned plurality of batteries is a removable battery.

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