Power supply device

Abstract

To provide a power supply device that converts electric power into stable electric power and supplies it.SOLUTION: A power supply device 1 includes a power generation unit (fuel cell 11), a power acquisition unit (power input terminal PI), a power conversion unit 12, a power storage unit (batteries 14-1 to 14-n), and a power output unit (power output terminal PO). The power generation unit generates first power. The power acquisition unit acquires second power from an external source. The power conversion unit receives the first power generated by the power generation unit, receives the second power acquired by the power acquisition unit, and transforms the voltage of the received power. The power storage unit stores the power transformed by the power conversion unit. The power output unit supplies the power stored in the power storage unit to an external power supply destination.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power supply device that converts power into stable power and supplies it.

Background Art

[0002] In recent years, with the regulations on greenhouse gas emissions, the electrification of automobiles has been progressing. Electric vehicles that are driven only by the power stored in a battery tend to have a short cruising range and take a long time to charge. Also, although electric vehicles do not emit carbon dioxide during driving, when the power they are charged with is generated by thermal power generation or the like, it is equivalent to emitting carbon dioxide.

[0003] As an automobile that does not have the problems of the above electric vehicles, fuel cell vehicles have attracted attention. Since the fuel cell provided in a fuel cell vehicle generates electricity by the chemical reaction of hydrogen and oxygen, the fuel cell vehicle does not emit carbon dioxide. Also, since the fuel cell has a high energy capacity, it is possible to extend the cruising range and shorten the fuel supply time. On the other hand, since the fuel cell generates electricity by a chemical reaction, its responsiveness to load fluctuations may be low, and it is necessary to combine it with a battery to cope with load fluctuations, but the battery deteriorates when it repeatedly charges and discharges.

[0004] As an example of solving the above problems, for example, Patent Document 1 (Japanese Patent Laid-Open No. 6-253409) is disclosed.

[0005] In Patent Document 1, during regeneration due to deceleration, the power supply device opens the first switch and accumulates the regenerative power in the capacitor. When the voltage value Vc of the capacitor exceeds the voltage value Vv of the battery, the power supply device connects the second switch and performs electrolysis in the electrolysis unit 55 until Vc and Vv become equal, and accumulates the generated hydrogen gas and oxygen gas in the gas chamber. The power supply device supplies the hydrogen gas to the cathode side of the fuel cell, supplies the oxygen gas to the anode side, generates electricity by the fuel cell, and charges the battery. The power supply device supplies the water generated on the anode side of the fuel cell from the water supply pipe to the water storage unit for reuse. When the fuel cell is stopped, the power supply device supplies hydrogen gas to the anode side and oxygen gas to the cathode side, and reacts the residual gas at each electrode to prevent the regenerative current from leading to the deterioration of the battery.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the power supply device of the above Patent Document 1, the rapid regenerative power is temporarily stored in the capacitor, and the voltage exceeding the charging voltage of the battery is consumed by electrolysis, thereby reducing the burden on the battery.

[0008] However, the device for performing electrolysis is expensive, and the cost of the power supply device of Patent Document 1 increases. Also, in the power supply device of Patent Document 1, even if electrolysis is performed with the power obtained by regeneration, the amount that can be reused for power generation as fuel is small, and it is difficult to improve the recovery efficiency.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a power supply device that converts power into stable power and supplies it.

Means for Solving the Problems

[0010] Aspects of the present invention are such that a power supply device includes a power generation unit, a power acquisition unit, a power conversion unit, a power storage unit, and a power output unit. The power generation unit generates first power. The power acquisition unit acquires second power from the outside. The power conversion unit receives the first power generated by the power generation unit, receives the second power acquired by the power acquisition unit, and transforms the received power into a charging voltage. The power storage unit stores the power transformed by the power conversion unit. The power output unit supplies the power stored in the power storage unit to an external power supply destination.

Effects of the Invention

[0011] According to an embodiment of the present invention, power can be converted into stable power and supplied.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

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Figure 11

Figure 12

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, substantially the same functions and components are denoted by the same reference numerals, and the description thereof is omitted or given only when necessary.

[0014] (First Embodiment) In the first embodiment, even if the voltage of the generated power is insufficient, the power is stored and supplied to the power supply destination, whereby the generated power can be efficiently and stably supplied to the power supply destination even in the case of, for example, off-grid. A power supply device will be described.

[0015] <Summary> The power supply device according to the first embodiment can generate, for example, a direct current, can obtain, for example, a direct current, and stably and efficiently supplies direct current power to various devices or systems.

[0016] The power supply device according to the first embodiment includes a power generation unit that generates power, a power acquisition unit that acquires external power, a power conversion unit that can input the power generated by the power generation unit and the power acquired by the power acquisition unit and can boost the input power, a power storage unit that stores the power boosted by the power conversion unit, and a power output unit that supplies the power stored in the power storage unit to an external load. The power generation unit may be, for example, a fuel cell.

[0017] The power storage unit includes a plurality of batteries that temporarily hold charge. In the power conversion unit, when receiving power, a plurality of capacitors are connected in parallel. In the power conversion unit, when supplying (discharging) power to a plurality of batteries, a plurality of capacitors are connected in series.

[0018] The power supply device according to the first embodiment further includes a power control unit that determines the number of capacitors connected in series based on the voltage value of the power storage state of a single capacitor and the remaining capacity or charging voltage of the battery. When discharging to the battery, the power conversion unit discharges by connecting in series the number of capacitors determined by the power control unit among the plurality of capacitors.

[0019] The power supply device according to the first embodiment further includes a plurality of charging switches that switch whether to charge each of the plurality of batteries, and a plurality of discharging switches that switch whether to discharge each of the plurality of batteries.

[0020] The power control unit of the power supply device according to the first embodiment determines at least one battery to be discharged from among the batteries for which the corresponding charging switch is OFF, and supplies power to an external power supply destination by turning on the discharging switch corresponding to the determined battery to be discharged.

[0021] Hereinafter, a specific example of the power supply device according to the first embodiment will be described.

[0022] <Configuration> FIG. 1 is a block diagram showing an example of the configuration of a power supply device 1 according to the first embodiment.

[0023] The power supply device 1 according to the first embodiment includes a fuel cell 11, a power conversion unit 12, a power control unit 13, a plurality of batteries 14-1 to 14-n, charging switches 15-1 to 15-n corresponding to the respective batteries 14-1 to 14-n, discharging switches 16-1 to 16-n corresponding to the respective batteries 14-1 to 14-n, a power input terminal PI, and a power output terminal PO.

[0024] The power supply device 1 is connected to an external load 2 via a power input terminal PI and a power output terminal PO, and is used in combination with the external load 2.

[0025] The external load 2 includes, for example, an inverter 21, a motor 22, and a regeneration unit 23. The inverter 21 is electrically connected to the power output terminal PO. The regeneration unit 23 is electrically connected to the power input terminal PI. A specific example of the external load 2 will be described later.

[0026] In the first embodiment, the power input terminal PI is an example of a power acquisition unit. The fuel cell 11 is an example of a power generation unit. The batteries 14-1 to 14-n are an example of a power storage unit. The power output terminal PO is an example of a power output unit.

[0027] Each component of the power supply device 1 will be described below.

[0028] <Fuel cell 11> The fuel cell 11 receives fuel supply, generates power, and supplies the generated power to the power conversion unit 12 according to the control of the power control unit 13. The fuel cell 11 receives, for example, the supply of hydrogen and oxygen as fuel, and generates power by a chemical reaction in an internal fuel cell. Hydrogen and oxygen are supplied to the fuel cell 11 from separate pipelines. Specifically, hydrogen is supplied to the anode (negative electrode) of the fuel cell 11. Oxygen is supplied to the cathode (positive electrode) of the fuel cell 11. The fuel cells provided in the fuel cell 11 may have a power generation voltage of less than 1V, for example, for each unit. The fuel cell 11 can output a high voltage by stacking (connecting in series) a plurality of fuel cells. In the first embodiment, the output voltage of the fuel cell 11 is not particularly limited.

[0029] The fuel cell 11 may include a reformer including a reforming function. In this case, the fuel supplied to the fuel cell 11 may be, for example, ethanol or methanol. When the fuel cell 11 includes a reformer, the fuel cell 11 reforms the fuel, generates hydrogen gas, and supplies hydrogen to the fuel cells.

[0030] <Power Conversion Unit 12> The first input terminal of the power conversion unit 12 is electrically connected to the fuel cell 11. The second input terminal of the power conversion unit 12 is electrically connected to the regeneration unit 23 of the external load 2 via the power input terminal PI.

[0031] The output terminal of the power conversion unit 12 is electrically connected to each one end of the charging switches 15-1 to 15-n.

[0032] The power conversion unit 12 receives power from the fuel cell 11, receives power from the regeneration unit 23 of the external load 2 via the power input terminal PI according to the control of the power control unit 13, converts the received power so that it is stabilized, and supplies the converted power to one end of the charging switches 15-1 to 15-n. More specifically, the power conversion unit 12 transforms the received power to the storage voltage (boosts when the voltage of the received power is lower than the charging voltage, and steps down when the voltage of the received power is higher than the charging voltage).

[0033] The power conversion unit 12 includes a plurality of capacitors. The power conversion unit 12 stores the generated power of the fuel cell 11 or the power received from the external load 2 via the power input terminal PI in at least one of the plurality of capacitors based on the control of the power control unit 13, and converts the voltage. Then, when the charging switches 15-1 to 15-n are ON, the power conversion unit 12 supplies the converted power to the batteries 14-1 to 14-n. The plurality of capacitors provided in the power conversion unit 12 is an example of a device that temporarily stores power. A specific example of the power conversion unit 12 will be described later with reference to FIGS. 2 and 3.

[0034] <Charging Switches 15-1 to 15-n> Each one end of the charging switches 15-1 to 15-n is electrically connected to the power conversion unit 12. Each other end of the charging switches 15-1 to 15-n is electrically connected to each one end of the batteries 14-1 to 14n.

[0035] Each of the charging switches 15-1 to 15-n switches between ON and OFF according to the control of the power control unit 13.

[0036] The description of the switching of the charging switches 15-1 to 15-n will be described later.

[0037] <Discharge switches 16-1 to 16-n> One end of each of the discharge switches 16-1 to 16-n is electrically connected to the other end of each of the batteries 14-1 to 14n. The other end of each of the discharge switches 16-1 to 16-n is connected to the power output terminal PO. The other end of each of the discharge switches 16-1 to 16-n is electrically connected to the inverter 21 of the external load 2 via the power output terminal PO.

[0038] Each of the discharge switches 16-1 to 16-n switches ON / OFF according to the control of the power control unit 13.

[0039] The description of the switching of the discharge switches 16-1 to 16-n will be described later.

[0040] <Batteries 14-1 to 14-n> Each of the batteries 14-1 to 14-n is associated with each of the charging switches 15-1 to 15-n, and further, is associated with each of the discharge switches 16-1 to 16-n. Specifically, one end of each of the batteries 14-1 to 14-n is electrically connected to the other end of each of the charging switches 15-1 to 15-n. The other end of each of the batteries 14-1 to 14-n is electrically connected to one end of each of the discharge switches 16-1 to 16-n.

[0041] Each of the batteries 14-1 to 14―n receives power from the power conversion unit 12 and performs charging when the corresponding charging switch 15-1 to 15-n is ON. Each of the batteries 14-1 to 14-n does not receive power from the power conversion unit 12 and does not perform charging when the corresponding charging switch 15-1 to 15-n is OFF.

[0042] Each of the batteries 14-1 to 14-n supplies power to a power supply destination such as the inverter 21 of the power generation device 2 via the power output terminal PO when the corresponding discharge switches 16-1 to 16-n are ON. Each of the batteries 14-1 to 14-n does not supply power to the power supply destination via the power output terminal PO when the corresponding discharge switches 16-1 to 16-n are OFF.

[0043] <Specific Example of the Configuration of the Power Conversion Unit 12> FIG. 2 is a block diagram showing an example of the configuration of the power conversion unit 12 according to the first embodiment.

[0044] The power conversion unit 12 includes a plurality of capacitor cell columns 121-1 to 121-r, switches 122-1 to 122-r, a first plus input terminal VI1+, a first minus input terminal VI1-, a second plus input terminal VI2+, a second minus input terminal VI2-, a plus output terminal VO+, and a minus output terminal VO-.

[0045] The power conversion unit 12 has a configuration in which r (r rows: r is an integer of 2 or more) capacitor cell columns 121-1 to 121-r are arranged in parallel.

[0046] The capacitor cell column 121-1 has a configuration in which c (c is an integer of 2 or more) capacitor cells 121-11 to 121-1c are connected in series. Each of the capacitor cells 121-11 to 121-1c can temporarily store power and includes, for example, a capacitor.

[0047] Similarly, each of the capacitor cell columns 121-2 to 121-r has a configuration in which capacitor cells 121-21 to 121-2c,..., 121-r1 to 121-rc are connected in series.

[0048] Therefore, the power conversion unit 12 includes a total of c × r capacitor cells 121-11 to 121-1c,..., 121-r1 to 121-rc.

[0049] The power conversion unit 12 includes two systems of power input terminals, namely, a first system including a first positive input terminal VI1+ and a first negative input terminal VI1-, and a second system including a second positive input terminal VI2+ and a second negative input terminal VI2-.

[0050] Using the first positive input terminal VI1+ and the first negative input terminal VI1-, the power generated by the fuel cell 11 is input to the power conversion unit 12.

[0051] Using the second positive input terminal VI2+ and the second negative input terminal VI2-, the power obtained from the power input terminal PI is input to the power conversion unit 12.

[0052] Each of the switches 122-1 to 122-r is associated with each of the capacitor cell strings 121-1 to 121-r. In the first embodiment, each of the switches 122-1 to 122-r is provided between the first positive input terminal VI1+ and each of the capacitor cell strings 121-1 to 121-r. However, each of the switches 122-1 to 122-r may be provided between the first negative input terminal VI1- and each of the capacitor cell strings 121-1 to 121-r.

[0053] Each of the switches 122-1 to 122-r can selectively switch to supply the power from the first positive input terminal VI1+ and the first negative input terminal VI1- to each of the capacitor cell strings 121-1 to 121-r, or to supply the power from the second positive input terminal VI2+ and the second negative input terminal VI2- to each of the capacitor cell strings 121-1 to 121-r according to the control of the power control unit 13. In other words, each of the switches 122-1 to 122-r switches whether to supply the power from the fuel cell 11 or the power from the external load 2 to each of the capacitor cell strings 121-1 to 121-r.

[0054] The output sides of each of the capacitor cell columns 121-1 to 121-r are electrically connected to the positive output terminal VO+ and the negative output terminal VO-.

[0055] Each of the capacitor cell columns 121-1 to 121-r can be individually specified for charging and discharging operations, and the operation can be switched based on the control of the power control unit 13. For this reason, the power conversion unit 12 can perform charging and discharging in parallel (simultaneously).

[0056] Note that the power conversion unit 12 may be composed of a plurality of capacitor cells having capacitors as shown in FIG. 2 above, or an equivalent circuit configuration may be realized within one module. That is, the power conversion unit 12 only needs to be able to charge by connecting a plurality of capacitors in parallel and discharge by connecting a plurality of capacitors in series.

[0057] <Switching control of switches 122-1 to 122-r for the power conversion unit 12 by the power control unit 13> For example, assume that the capacitor cell columns to be charged are the capacitor cell columns 121-1 and 121-r. In this case, during charging, the power control unit 13 places the capacitors provided in each capacitor cell 121-11 to 121-1c,..., 121-r1 to 121-rc included in the capacitor cell columns 121-1 and 121-r to be charged in a parallel connection state. Then, the power control unit 13 turns on the switches 122-1 and 122-r corresponding to the capacitor cell columns 121-1 and 121-r to be charged, and supplies power to the capacitor cell columns 121-1 and 121-r to be charged via the switches 122-1 and 122-r to perform charging.

[0058] The same applies when the combination of the capacitor cell columns to be charged is not the capacitor cell columns 121-1 and 121-r. The power control unit 13 places the capacitors provided in the capacitor cells included in the capacitor cell columns to be charged in a parallel connection state and supplies power.

[0059] For example, assume that the capacitor cell arrays to be discharged are capacitor cell array 121-1 and capacitor cell array 121-r. In this case, during discharge, the power control unit 13 turns off the switches 122-1, 122-r corresponding to the capacitor cell arrays 121-1, 121-r to be discharged, and connects the capacitors provided in each capacitor cell 121-11 to 121-1c,..., 121-r1 to 121-rc included in the capacitor cell arrays 121-1, 121-r to be discharged in series. Then, the power control unit 13 supplies the power of the capacitor cell arrays 121-1, 121-r to be discharged to at least one of the batteries 14-1 to 14-n via at least one of the output terminals VO+, VO- and the charging switches 15-1 to 15-n. The power stored in at least one of the batteries 14-1 to 14-n is supplied from the power output terminal PO to the power supply destination via at least one of the discharge switches 16-1 to 16-n.

[0060] The same applies when the combination of the capacitor cell arrays to be discharged is not capacitor cell arrays 121-1, 121-r. The power control unit 13 turns off the switch corresponding to the capacitor cell array to be discharged, connects the capacitors provided in the capacitor cells included in the capacitor cell array to be discharged in series, and supplies power from the capacitor cell array to be discharged to the battery.

[0061] The power control unit 13 determines from which of the first positive input terminal VI1+ and the first negative input terminal VI1- and the second positive input terminal VI2 and the second negative input terminal VI2- to supply power to the capacitor cell arrays 121-1 to 121-r.

[0062] For example, the power control unit 13 monitors the amount of power stored in the capacitor cell arrays 121-1 to 121-r.

[0063] The power control unit 13 may supply power to the capacitor cell string with the stored power amount less than a predetermined value from the first positive input terminal VI1+ and the first negative input terminal VI1-. The power control unit 13 may supply power to the capacitor cell string with the stored power amount greater than or equal to a predetermined value from the second positive input terminal VI2+ and the second negative input terminal VI2-.

[0064] In such control, the power generated by the fuel cell 11 is sequentially supplied to the capacitor cell string with less remaining stored power. On the other hand, a certain number of capacitor cell strings are kept in a state of having less stored power so as to absorb the power (with a large instantaneous power amount) accompanied by a rapid output change generated by the external load 2 such as a regenerative brake. In this way, the power control unit 13 determines, for example, the power generation amount of the fuel cell 11, the generated power of the fuel cell 11, and the number of capacitor cell strings to be charged so that the power supply is not interrupted from the output power amount from the power output terminal PO and the power amount stored in the batteries 14-1 to 14-n. In other words, the power control unit 13 controls to leave a certain number of capacitor cell strings empty so as to absorb the power generated irregularly such as regenerative power. On the other hand, the power control unit 13 controls to execute power generation by a power generation device such as a fuel cell so as not to cause a power outage and to charge the battery using the capacitor cell string.

[0065] <Specific Example of Capacitor Cell 121-11> In the following, regarding the capacitor cells 121-11 to 121-1c, 121-21 to 121-2c, 121-r1 to 121-rc, the capacitor cell 121-11 will be described as a representative. Note that the other capacitor cells 121-12 to 121-1c, 121-21 to 121-2c, 121-r1 to 121-rc also have the same characteristics as the capacitor cell 121-11 to be described, and thus the description will be omitted.

[0066] FIG. 3 is a circuit diagram showing an example of the configuration of the capacitor cell 121-11 provided in the power conversion unit 12 according to the first embodiment.

[0067] The capacitor cell 121-11 includes a plus input terminal I+, a minus input terminal I-, a capacitor 1211, a bypass switch 1212, a series connection switch 1213, a ground switch 1214, a voltmeter 1215, a plus output terminal O+, and a minus output terminal O-.

[0068] The plus input terminal I+ is electrically connected to one end of the bypass switch 1212 and one end of the series connection switch 1213.

[0069] The other end of the bypass switch 1212 is electrically connected to the plus output terminal O+, one end of the capacitor 1211, and one end of the voltmeter 1215.

[0070] The other end of the series connection switch 1213, the other end of the capacitor 1211, and the other end of the voltmeter 1215 are electrically connected to one end of the ground switch 1214.

[0071] The other end of the ground switch 1214 is electrically connected to the minus input terminal I- and the minus output terminal O-.

[0072] <Capacitor 1211> The capacitor 1211 may be, for example, an electric double layer capacitor, a lithium ion capacitor, or a device that stores electricity by static electricity. The capacitor 1211 may be used alone, or a plurality of capacitors may be connected in series or in parallel and used.

[0073] FIG. 4 is a graph showing an example of the change in voltage during charging of the capacitor 1211 according to the first embodiment.

[0074] In FIG. 4, the vertical axis represents the voltage across the capacitor 1211, and the horizontal axis represents the passage of time.

[0075] Vf is the rated voltage of the capacitor.

[0076] When the charging of the capacitor 1211 starts, the voltage across the capacitor 1211 rises. As the voltage across the capacitor 1211 rises, the difference from the charging voltage decreases and the current flowing decreases, so the voltage rise gradually slows down over time.

[0077] FIG. 5 is a graph showing an example of the voltage change during discharge of the capacitor 1211 according to the first embodiment.

[0078] In FIG. 5, the vertical axis represents the voltage across the capacitor 1211, and the horizontal axis represents the passage of time.

[0079] When the discharge of the capacitor 1211 starts, the voltage across the capacitor 1211 begins to drop. As the voltage across the capacitor 1211 drops, the amount of current that can be discharged decreases, so the voltage drop becomes gradual over time.

[0080] FIG. 6 is a graph showing an example of the voltage change during discharge when the capacitor 1211 according to the first embodiment includes a plurality of capacitors connected in series.

[0081] In FIG. 6, the vertical axis represents the voltage across the capacitor 1211 including two capacitors connected in series, and the horizontal axis represents the passage of time. The actual curve Ct in FIG. 6 shows the change in the voltage across the capacitor 1211 when discharging the capacitor 1211 including two capacitors connected in series. The dotted curve Cs in FIG. 6 shows the change in the voltage across each of the two capacitors when two capacitors 1211 are connected in series.

[0082] Vu is set as the upper limit value of the charging voltage for charging the batteries 14-1 to 14-n when the corresponding switches 15-1 to 15-n are ON.

[0083] Vl is set as the lower limit value of the charging voltage for charging the batteries 14-1 to 14-n when the corresponding switches 15-1 to 15-n are ON.

[0084] When the discharge from two serially connected capacitors 1211 starts, the voltage across the two serially connected capacitors 1211 starts to decrease from, for example, Vu. When the voltage across the two serially connected capacitors 1211 reaches Vl, the charging current to the batteries 14-1 to 14-n when the corresponding switches 15-1 to 15-n are ON stops flowing, and the voltage does not decrease below Vl. At this time, the voltage across each of the two serially connected capacitors 1211 is obtained by dividing Vl by the number of series connections, and in the example of FIG. 6, it becomes Vl / 2.

[0085] The voltage of the capacitor 1211 changes according to the stored capacitance. By changing the number of series connections of the capacitors 1211, the output voltage of the plurality of serially connected capacitors 1211 can be adjusted.

[0086] <Bypass switch 1212> The bypass switch 1212 turns on g1 of the bypass switch 1212 provided in the capacitor 1211 of each capacitor cell 121-11 to 121-1c belonging to the capacitor cell row 121-1 to allow current to flow when charging the capacitors 1211 connected in parallel, and when excluding the discharge of the capacitor cell 121-11 from the capacitor cell row 121-1 during discharge. g1 is controlled by the power control unit 13.

[0087] <Series connection switch 1213> The series connection switch 1213 turns on g2 to allow current to flow when adding the capacitor cell 121-11 to the series connection of the capacitor cells 121-11 to 121-1c belonging to the capacitor cell row 121-1 during discharge. g2 is controlled by the power control unit 13.

[0088] <Grounding switch 1214> The grounding switch 1214 allows current to flow by turning on g3 when charging by connecting in parallel the capacitors 1211 provided in each of the capacitor cells 121-11 to 121-1c belonging to the capacitor cell array 121-1, and when discharging as the negative side ends of the serially connected capacitor cells 121-11 to 121-1c belonging to the capacitor cell array 121-1. g3 is controlled by the power control unit 13. When all the grounding switches 1214 of the capacitor cells 121-11 to 121-1c belonging to the capacitor cell array 121-1 are turned off, the capacitor cell array 121-1 is invalidated and neither charging nor discharging occurs.

[0089] In the first embodiment, the bypass switch 1212, the series connection switch 1213, and the grounding switch 1214 may be of the same type of device. As the bypass switch 1212, the series connection switch 1213, and the grounding switch 1214, for example, a switch device capable of controlling the flow of current such as an FET (Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or a thyristor may be used.

[0090] <Voltmeter 1215> The voltmeter 1215 detects the voltage value VS across the capacitor 1211. The voltmeter 1215 outputs the detected voltage value VS to, for example, the power control unit 13.

[0091] In the first embodiment, the voltmeter 1215 does not have to be provided in all the capacitor cells 121-11 to 121-1c, 121-21 to 121-2c, 121-r1 to 121-rc. For example, a device such as the power control unit 13 may estimate the voltage values of other capacitors provided in other capacitor cells based on the voltage value received from a specific capacitor cell provided in a specific capacitor cell.

[0092] <Power control unit 13> The power control unit 13 receives and monitors, for example, at regular intervals, the voltage value VS of the capacitor 1211 detected by the voltmeter 1215.

[0093] Based on the voltage value VS of the capacitor 1211 provided in each of the capacitor cells 121-11 to 121-1c, 121-21 to 121-2c, 121-r1 to 121-rc, the power control unit 13 determines the number of connections of the batteries 14-1 to 14-n.

[0094] The power control unit 13 executes various controls related to the operation of the power supply device 1. Examples of the controls executed by the power control unit 13 include power generation control of the fuel cell 11, power conversion control of the power conversion unit 12, battery charging control of the power conversion unit 12, output power control, charge switch control, charging control, power output switch control, etc. Hereinafter, examples of the controls executed by the power control unit 13 will be described.

[0095] <Power generation control of the fuel cell 11> Based on the transition of the stored power in the batteries 14-1 to 14-n and the output power supplied to the outside, the power control unit 13 determines whether it is expected that the stored power in the batteries 14-1 to 14-n will be insufficient, and whether the available space in the batteries 14-1 to 14-n that can store the external power generation power supplied irregularly from the external load 2 is below a predetermined capacity.

[0096] Then, when it is expected that the stored power in the batteries 14-1 to 14-n will be insufficient, the power control unit 13 operates the fuel cell 11 or increases the power generation amount of the fuel cell 11 to increase the stored power.

[0097] When the power control unit 13 determines that the available space in the batteries 14-1 to 14-n that can store the external power generation power supplied irregularly from the external load 2 is below a predetermined capacity, the power control unit 13 stops the fuel cell 11 or decreases the power generation amount of the fuel cell 11 to reduce the stored power.

[0098] Note that the fuel cell 11 needs to maintain the temperature at which hydrogen and oxygen chemically react for power generation. Once the fuel cell 11 stops generating power, the temperature drops, and it may be necessary to heat it again to start generating power. Therefore, it is desirable for the power control unit 13 to control the fuel cell 11 so as to reduce the output without stopping it as much as possible.

[0099] <Power conversion control of the power conversion unit 12> Based on the voltage value VS of the capacitor 1211 provided in each of the capacitor cells 121-11 to 121-1c, …, 121-r1 to 121-rc, the power control unit 13 controls which capacitor bank among the capacitor banks 121-1 to 121-r provided in the power conversion unit 12 to charge, and which capacitor bank to discharge to output power.

[0100] Based on the voltage value VS of the capacitor 1211 provided in each of the capacitor cells 121-11 to 121-1c, …, 121-r1 to 121-rc, when discharging, the power control unit 13 controls which capacitors 1211 provided in the capacitor cells of the discharging capacitor bank to connect and discharge.

[0101] FIG. 7 is a diagram showing an example of power conversion control for the power conversion unit 12 executed by the power control unit 13 according to the first embodiment.

[0102] In the example of FIG. 7, assume that the capacitor 1211 is charged up to 10V, and the capacitor bank 121-1 includes 10 capacitors 121-11 to 121-1c. Also, assume that the charging voltage of each of the batteries 141-1 to 141-n is 25V.

[0103] First, as shown in the charging state, the power control unit 13 connects in parallel all the capacitors 1211 provided in the capacitor cells 121-11 to 121-1c belonging to the capacitor bank 121-1, and applies power from the first positive input terminal VI1+ and the first negative input terminal VI1-, or the second positive input terminal VI2+ and the second negative input terminal VI2- to charge all the capacitors 1211 provided in the capacitor cells 121-11 to 121-1c belonging to the capacitor bank 121-1.

[0104] In the example of (1) in FIG. 7, charging is performed until the voltage across the plurality of capacitors 1211 connected in parallel reaches 10V.

[0105] Next, the power control unit 13 determines the number of capacitors 1211 to be connected in series so that the voltage is higher than the charging voltage for the batteries 141-1-1 to 141-n, and for example, connects in series the determined number of capacitors 1211 as in (2) the first discharge state.

[0106] In the example of (2) the first discharge state in FIG. 7, five 10V capacitors 1211 are connected in series, and 50V is applied to the batteries 141-1 to 141-n.

[0107] Power is discharged from the five charged capacitors 1211, and the voltage applied to the batteries 141-1-1 to 141-n also decreases. When the voltage reaches 25V, which is the charging voltage of the batteries 141-1-1 to 141-n, the voltage difference between the five charged capacitors 1211 and the batteries 141-1-1 to 141-n disappears, and thus the batteries 141-1-1 to 141-n cannot be charged.

[0108] At this time, the voltage of each of the five capacitors 1211 connected in series is approximately 5V.

[0109] Next, the power control unit 13 disconnects the series connection of the five capacitors 1211 connected in series previously in the power conversion unit 12 as in (3) Discharge state 2, and connects a new set of five capacitors 1211 different from the five capacitors connected in series previously in series.

[0110] As a result, five 10V capacitors 1211 are newly connected in series, and 50V is applied to the batteries 141-1-1 to 141-n by the five newly connected capacitors 1211 in series.

[0111] Power is discharged from the five newly connected capacitors 1211 in series, and the voltage applied to the batteries 141-1-1 to 141-n also decreases. When the voltage reaches 25V, which is the charging voltage of the batteries 141-1-1 to 141-n, the voltage difference between the five newly connected capacitors 1211 in series and the batteries 141-1-1 to 141-n disappears, so the batteries 141-1-1 to 141-n cannot be charged.

[0112] At this time, the voltage of each of the five newly connected capacitors 1211 is approximately 5V.

[0113] Next, the power control unit 13 changes the connection of the power conversion unit 12 to the connection shown in (4) Discharge state 3. Specifically, the power control unit 13 connects the five capacitors 1211 connected in series previously and the five newly connected capacitors 1211 in series, for a total of ten capacitors in series. As a result, 50V is applied to the batteries 141-1 to 141-n by connecting ten 5V capacitors in series.

[0114] Power is discharged from the ten capacitors 1211 connected in series, and the voltage applied to the batteries 141-1 to 141-n also decreases. When the voltage reaches 25V, which is the charging voltage of the batteries 141-1 to 141-n, the voltage difference between the ten capacitors 1211 connected in series and the batteries 141-1 to 141-n disappears, so the batteries 141-1 to 141-n cannot be charged. At this time, the voltage of each capacitor 1211 is approximately 2.5V.

[0115] In the example of FIG. 7, since the batteries 141-1 to 141-n cannot be charged any further, the power control unit 13 (1) returns to the charging state and performs charging of the capacitor 1211 again.

[0116] As described above, the power control unit 13 determines the number of capacitors to be connected in series, switches the capacitors to be connected in series, and controls the connection of the capacitor cells 121-11 to 121-1c,..., 121-r1 to 121-rc inside the power conversion unit 12 based on the voltage of the capacitor 1211 and the charging voltages of the batteries 141-1 to 141-n.

[0117] <Battery charging control of power conversion unit 12> The power control unit 13 determines which of the plurality of batteries 14-1 to 14-n to charge, and supplies the power output from the power conversion unit 12 to the determined battery to be charged for charging.

[0118] The power control unit 13 may charge a plurality of batteries to be charged simultaneously, or may charge any one of the plurality of batteries to be charged. Since the batteries determined to be charged cannot be discharged simultaneously, the power control unit 13 excludes the batteries to be charged from the discharge targets.

[0119] As a determination condition for the power control unit 13 to determine the battery to be charged, for example, a battery whose stored power is below a predetermined ratio such as 30% or less may be determined as the battery to be charged.

[0120] In order to prevent the battery from deteriorating, it is desirable for the power control unit 13 to perform control to prevent the battery from being used until the stored capacity of the battery reaches 0%.

[0121] In order to prevent the battery from deteriorating, the power control unit 13 may perform control to stop charging when the stored capacity of the battery exceeds a predetermined ratio such as 80%.

[0122] <Output power control> The power control unit 13 determines from which of the plurality of batteries 14-1 to 14-n to discharge and output power, and connects the determined battery to be discharged to the power output terminal PO to output power.

[0123] The power control unit 13 may determine a plurality of batteries as discharge targets according to the capacity of the output power, and connect the plurality of determined batteries to be discharged to the power output terminal PO to perform the output.

[0124] As a determination criterion for the power control unit 13 to determine the battery to be discharged, for example, a battery that is charged exceeding a predetermined ratio such as 70% or more of the stored power may be determined as the discharge target.

[0125] The power control unit 13 may determine any one or a plurality of the batteries to be discharged.

[0126] When determining the battery to be discharged, the power control unit 13 may use the degree of deterioration of each of the batteries 14-1 to 14-n. Specifically, when the stored power exceeds a predetermined value such as 70% or more, the power control unit 13 may determine the battery with the lowest estimated degree of deterioration as the discharge target. Further, when the stored power is below a predetermined value such as 30% or less, the power control unit 13 may perform control to stop the discharge.

[0127] <Charge switch control> As described above, each of the charge switches 15-1 to 15-n is provided corresponding to each of the batteries 14-1 to 14-n. When each of the charge switches 15-1 to 15-n is ON, the output power from the power conversion unit 12 is supplied to each of the batteries 14-1 to 14-n. When each of the charge switches 15-1 to 15-n is OFF, the output power from the power conversion unit 12 is not supplied to each of the batteries 14-1 to 14-n.

[0128] When the battery to be charged is determined, the power control unit 13 turns on the charging switch corresponding to the determined battery to be charged, and causes a current to flow from the power conversion unit 12 to the battery to be charged.

[0129] <Charge control> FIG. 8 is a timing chart showing an example of charge control when charging the batteries 14-1 to 14-n according to the first embodiment.

[0130] In FIG. 8, PWM indicates a signal for turning on / off the charging switch 15. Voltage indicates the voltage applied to the battery to be charged. Current is the current flowing through the battery to be charged.

[0131] The PWM indicating ON is transmitted to the charging switches 15-1 to 15-n at a constant period, and the charging switches 15-1 to 15-n that receive the PWM indicating ON are turned on for a predetermined period. When the charging switches 15-1 to 15-n that receive the PWM indicating ON are turned on, the voltage supplied to the batteries 14-1 to 14-n corresponding to the charging switches 15-1 to 15-n that receive the PWM rises, and a current flows. As a result, the batteries 14-1 to 14-n corresponding to the charging switches 15-1 to 15-n that receive the PWM indicating ON are charged. When the PWM changes from ON to OFF, the charging switches 15-1 to 15-n that receive the PWM indicating OFF are turned off. When the charging switches 15-1 to 15-n are turned off, the current from the power conversion unit 12 to the batteries 14-1 to 14-n is cut off, and the charging of the batteries 14-1 to 14-n corresponding to the charging switches 15-1 to 15-n that receive the PWM indicating OFF stops.

[0132] In this way, by intermittently charging the batteries 14-1 to 14-n, the amount of current to be charged can be limited, and deterioration of the batteries 14-1 to 14-n can be prevented.

[0133] <Power output switch control> As described above, each of the discharge switches 16-1 to 16-n is provided corresponding to each of the batteries 14-1 to 14-n. When each of the discharge switches 16-1 to 16-n is ON, it connects each of the batteries 14-1 to 14-n to the output terminal PO and supplies power from the power output terminal PO to the external load 2.

[0134] The power control unit 13 determines the battery to be discharged to output power among the batteries 14-1 to 14-n. The power control unit 13 turns on the discharge switch corresponding to the battery to be discharged and causes power to be supplied from the battery to be discharged to the external load 2 via the corresponding ON discharge switch.

[0135] <An example of the external load 2> The external load 2 shown in FIG. 1 above is an example of an object to which the power supply device 1 according to the first embodiment supplies power. As described above, the external load 2 includes an inverter 21, a motor 22, and a regeneration unit 23.

[0136] The inverter 21 is a driver for driving the motor 22.

[0137] The motor 22 generates power by receiving power supply from the inverter 21. Also, the motor 22 may be capable of generating electricity by external power.

[0138] The regeneration unit 23 recovers the power generated by the motor 22. The power recovered by the regeneration unit 23 is returned to the power supply device 1 from the power input terminal PI.

[0139] The external load 2 is not limited to the above example and can be changed to various devices or systems. In an environment where there are components that consume power and components that generate power, the power supply device 1 according to the first embodiment and the external load 2 can be applied.

[0140] <Operational effects> In the power supply device 1 according to the first embodiment described above, since the power conversion unit 12 realizes voltage boosting by changing the connection of a plurality of capacitors 1211, it is possible to suppress switching losses such as those of a DC-DC converter, and the voltage can be converted with high efficiency.

[0141] Also, in the power supply device 1 according to the first embodiment, since the power is temporarily stored in the capacitor 1211 and then output, it is possible to take in both power with large output fluctuations and power with a low voltage, and stable power can be output.

[0142] In the power supply device 1 according to the first embodiment, power can be supplied to various devices or systems even in an off-grid state (a state not connected to the commercial power grid), the generated power can be stabilized, and efficient utilization of power can be realized.

[0143] In the power supply device 1 according to the first embodiment, even power with large load fluctuations such as regenerative power can be efficiently charged while reducing the burden on the batteries 14-1 to 14-n.

[0144] (Second Embodiment) In the second embodiment, Examples 1 to 4 of the power supply device 1 described in the first embodiment will be described.

[0145] <Example 1: Fuel Cell Vehicle> FIG. 9 is a diagram showing an example of a fuel cell vehicle (electric vehicle) 3 of Example 1.

[0146] In Example 1, the power supply device 1 supplies driving power to the fuel cell vehicle 3. The power supply device 1 acquires regenerative power from the drive mechanism of the fuel cell vehicle 3.

[0147] The fuel cell vehicle 3 includes the power supply device 1 and a drive mechanism 2a. The drive mechanism 2a corresponds to the external load 2 described in the first embodiment.

[0148] The fuel cell vehicle 3 receives power supply from the power supply device 1, generates driving force by the driving mechanism 2a, and runs. When the fuel cell vehicle 3 decelerates, the regenerative power of the motor 22 of the driving mechanism 2 is regenerated by the regeneration unit 23 to generate braking force.

[0149] The regenerated power is supplied to the power supply device 1 and stored in at least one of the batteries 14-1 to 14-n inside the power supply device 1.

[0150] As described above, by using the power supply device 1 according to the first embodiment as the power supply source of the fuel cell vehicle 3, it is possible to suppress the deterioration of the batteries 14-1 to 14-n even when the regenerative brake is used, and to extend the operation period of the fuel cell vehicle 3 and the power supply device 1.

[0151] <Example 2: Power supply system to a station> FIG. 10 is a diagram showing an example of a power supply system to the station 6 of Example 2.

[0152] In Example 2, the power supply device 1 is installed at the station 6 and supplies the power used at the station 6.

[0153] In Example 2, the electric train 5 corresponds to the external load 2. The electric train 5 runs by receiving power supply from the overhead wire 7.

[0154] When the electric train 5 approaches the station 6, it decelerates by the regenerative brake. The power regenerated from the regenerative brake is returned to the overhead wire 7. The power supply device 1 acquires the regenerative power returned from the electric train 5 to the overhead wire 7 and absorbs and stores it.

[0155] In addition, the power supply device 1 may supply power to the overhead wire 7 when the electric train 5 starts.

[0156] As described above, by installing the power supply device 1 at the station 6, the regenerative power of the electric train 5 can be effectively utilized.

[0157] In the case of the regenerative brake of a normal train, when there is a train to be consumed nearby, or when there is no substation nearby that can absorb the regenerative power, it cannot be effectively utilized and may consume power wastefully. However, in Example 3, since the acceleration and deceleration of the train 5 are mainly performed around the station 6, the power generated by the regenerative brake can be effectively utilized.

[0158] Also, in Example 3, since power can be supplied to the station 6 even off the grid, a facility that is resistant to disasters such as power outages can be constructed.

[0159] <Example 3: Elevator System> FIG. 11 is a diagram showing an example of the elevator system of Example 3.

[0160] The power supply device 1 supplies power to each of the motors 2b and 2c corresponding to each of the elevators 4-1 and 4-2. When raising the cars of the elevators 4-1 and 4-2, the power supply device 1 supplies power to the motors 2b and 2c, and when the cars of the elevators 4-1 and 4-2 are descending, it acquires the regenerative power.

[0161] Each of the elevators 4-1 and 4-2 ascends by winding up the cable by each of the motors 2b and 2c, and descends by paying out the cable.

[0162] In the example of FIG. 11, the elevator 4-1 is ascending and the elevator 4-2 is descending.

[0163] In this case, the power supply device 1 supplies power to the motor 2b, and the elevator 4-1 is ascending as the motor 2b winds up the cable.

[0164] On the one hand, although the elevator 4-2 tends to fall due to gravity, a regenerative brake is generated by adjusting the regenerative power with the motor 2c, the cable payout is moderated, and the elevator 4-2 descends at an appropriate speed. The power regenerated from the motor 2c is returned to the power supply device 1, stored in at least one of the batteries 14-1 to 14-n provided inside the power supply device 1, and used as power for ascending.

[0165] As described above, in the elevator system of Embodiment 3, energy can be regenerated and power can be effectively utilized when the elevator 4-1 or the elevator 4-2 descends. Further, since the power supply device 1 can supply power to the elevator system even off-grid, the elevator system can be operated even during a power outage, and a safe system without problems such as entrapment can be provided.

[0166] <Example 4: Off-grid House> FIG. 12 is a diagram showing an example of the off-grid house 8 of Embodiment 4.

[0167] The off-grid house 8 includes a power supply device 1, a solar power generation panel 9, and a wind power generation device 10.

[0168] The power generated by the solar power generation panel 9 and the wind power generation device 10 is supplied to the power supply device 1 and stored in at least one of the batteries 14-1 to 14-n provided inside the power supply device 1.

[0169] The power generated by the solar power generation panel 9 and the wind power generation device 10 and the power generated by the fuel cell 11 are stored in the batteries 14-1 to 14-n and supplied to the off-grid house 8 as household power.

[0170] The power supply device 1 obtains the power regenerated by renewable energy and supplies the power consumed in the off-grid house 8 to the off-grid house 8.

[0171] The power supply device 1 can store electricity in the plurality of capacitors 1211 of the power conversion unit 12 once, so that it can store electricity in the batteries 14-1 to 14-n even when the generated voltage is low (weak sunlight, gentle breeze, etc.), increase the operating time of power generation by renewable energy, and is effective for energy saving.

[0172] The off-grid house 8 is preferably a house compatible with DC power supply. A house compatible with DC power supply does not require a power converter and has no conversion loss from DC to AC, so power consumption can be made more efficient. When performing DC power supply to the off-grid house 8, the batteries 14-1 to 14-n only need to be able to supply power to the off-grid house 8 at about 400V.

[0173] As described above, by using the power supply device 1 according to the first embodiment, off-grid power supply can be efficiently and stably performed in various applications.

[0174] Note that although Examples 1 to 4 were used to describe the object to which the power supply device 1 according to the first embodiment is applied, it is not limited thereto, and the power supply device 1 can be used in various other scenes. For example, in a system including a device that consumes power and a device that generates power, the power supply device 1 according to the first embodiment can be used.

[0175] Each of the above embodiments is an example and is not intended to limit the scope of the invention. Each of the above embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Each of the above embodiments and its modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0176] 1... Power supply device, 11... Fuel cell, 12... Power conversion unit, 13... Power control unit, 14-1 to 14-n... Batteries, 15-1 to 15-n... Charging switches, 16-1 to 16-n... Discharging switches, 2... External load, 21... Inverter, 22... Motor, 23... Regeneration unit, 121-1 to 121-r... Capacitor cell arrays, 121-11 to 121-rc... Capacitor cells, 1211... Capacitor, 1212... Bypass switch, 1213... Series connection switch, 1214... Grounding switch, 1215... Voltmeter, 3... Fuel cell vehicle, 2a... Driving mechanism, 2b, 2c... Motors, 4-1, 4-2... Elevators, 5... Train, 6... Station, 7... Overhead line, 8... Off-grid house, 9... Photovoltaic power generation panel, 10... Wind power generation

Claims

1. A power generation unit that generates first power, A power acquisition unit for acquiring second power from the outside, A power conversion unit that receives the first power generated by the power generation unit, receives the second power acquired by the power acquisition unit, and transforms the voltage of the received power, A power storage unit that stores the power transformed by the power conversion unit, A power output unit for supplying the power stored in the power storage unit to an external power supply destination, A power supply device comprising the above.

2. The power supply device according to Claim 1, wherein the power generation unit is a fuel cell.

3. The power conversion unit comprises a plurality of capacitors, When the power conversion unit receives at least one of the first power and the second power, the power conversion unit connects the plurality of capacitors in parallel, and when discharging the boosted power to the power storage unit, the power conversion unit connects the plurality of capacitors in series. The power supply device according to Claim 1.

4. Further comprising a control unit that determines the number of series connections regarding the plurality of capacitors when the power conversion unit discharges the power to the power storage unit based on the voltage value of each of the plurality of capacitors and the power amount of the power storage unit, When the power conversion unit discharges the power to the power storage unit, the power conversion unit connects the capacitors of the number of series connections among the plurality of capacitors in series to perform discharging. The power supply device according to Claim 3.

5. The power storage unit includes a plurality of batteries, A plurality of charging switches corresponding to each of the plurality of batteries, which turn ON when charging the corresponding battery and turn OFF when not charging, A plurality of discharging switches corresponding to each of the plurality of batteries, which turn ON when discharging from the corresponding battery and turn OFF when not discharging, Further comprising, Determining a battery to be discharged from among the batteries for which the corresponding charging switch is OFF and which are not in a charged state, turning ON the discharging switch corresponding to the battery to be discharged, and supplying power to the power supply destination via the power output unit. The power supply device according to Claim 1.

6. A power supply device according to Claim 1, A drive mechanism that receives power from the power supply device, Comprising, The power acquisition unit acquires regenerative power from the drive mechanism. An electric vehicle.

7. The power supply device according to Claim 1 supplies power to a station, The power acquisition unit acquires regenerative power from a train via an overhead wire. A power supply system.

8. The power supply device according to claim 1 supplies power to a motor that moves the elevator car up and down, The power acquisition unit acquires regenerative power from the motor when the elevator car descends. Power supply system.

9. The power supply device according to claim 1, An off-grid house that receives power from the power supply device, Comprising, The power acquisition unit acquires power regenerated by renewable energy. Power supply system.

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