Power supply device

Abstract

To provide a power supply device that enables electric power to be supplied stably even when a large current discharge is requested, and the charge efficiency of which is good.SOLUTION: A power storage device between an input power supply that supplies electricity and a load is constituted so that a redox flow cell 1 and a secondary cell 3 are connected in parallel via a control circuit 6, with the upper limit of a charge voltage of the redox flow cell 1 being set to be higher than the upper limit of charge voltage of the secondary cell 3. The control circuit 6 includes a voltage sensor 5 for measuring the common voltage between the redox flow cell 1 and the secondary cell 3, and an electromagnetic switch element MC2 is opened / closed on the basis of the voltage value of the voltage sensor 5, whereby the redox flow cell 1 and the secondary cell 3 are switched between single connection and parallel connection in charging time. A bypass diode 4 of which the direction of output current from the secondary cell 3 is made a forward direction is included so as to be connected in parallel to the electromagnetic switch element MC2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power supply device that can stably supply power even when a large current discharge is required and has good charging efficiency.

Background Art

[0002] The applicant of the present application has proposed a power supply system suitably used for emergency power supply (Patent Document 1). In this power supply system, a redox flow battery is adopted. This power supply system includes a battery body (a cell stack in which a plurality of battery cells are stacked) and an electrolyte tank. The electrolyte in the electrolyte tank is circulated through the battery body by a pump and returned to the electrolyte tank. By circulating the electrolyte, charge and discharge can be performed with the electrolyte in the electrolyte tank via the battery body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the redox flow battery employed in the power supply system of Patent Document 1, when the internal resistance is high, the output voltage decreases when a large current discharge at startup or a suddenly occurring large current discharge is required. In particular, in a secondary battery using only a redox flow battery during discharge, when a sudden large current discharge is required and an attempt is made to pass a large current, the voltage of the redox flow battery drops and falls below the voltage operating range of the redox flow battery, resulting in a problem that it stops operating. To solve this problem, it is also conceivable to vary the output of the redox flow battery by increasing the number of cells of the redox flow battery and switching the connection positions of the cells. However, increasing the number of cells requires a new design of the redox flow battery. Considering the amount of sudden large current discharge required, the design has to be made towards larger size. Furthermore, when combined with a switching mechanism for varying the number of cells, the structure becomes complicated and the control becomes difficult. And these may significantly increase the manufacturing cost and risk losing the competitiveness as a product. The inventor has arrived at the present invention that can supply products at a lower cost and can supply power even during large current discharge.

[0005] In addition, since the redox flow battery has a high internal resistance, there are also the following problems during charging. Since the redox flow battery has a high internal resistance of the battery cell, the voltage tends to rise during charging. Especially when charging with a large current, it easily reaches the upper limit voltage of the battery before reaching full charge. If the upper limit voltage of the battery is exceeded, gas generation from the electrode surface due to electrolysis, individual differences in battery cells, and non-uniformity of the electrolyte flow in the battery cells may cause local overcharging, increasing the possibility of precipitation of vanadium compounds. To prevent this, the charging current must be suppressed so as to be below a predetermined charging voltage, which requires a long time for charging and deteriorates the efficiency. In addition, when the charging power source is wind power generation or solar power generation, since the current fluctuation is large, in order to properly charge the redox flow battery, there is a problem that the power generation capacity of the power generation facility must be suppressed and electricity must be discarded during a time period with a large power generation amount.

[0006] Therefore, an object of the present invention is to provide a power supply device that can stably supply power even when a large current discharge is required and has good charging efficiency.

[0007] Other objects of the present invention will become apparent from the following description.

Means for Solving the Problem

[0008] The above problems are solved by the following inventions.

[0009] (Claim 1) In a power supply device in which a battery device is connected between an input power supply for supplying power and a load, the battery device is configured such that a redox flow battery (1) and a secondary battery (3) other than the redox flow battery are connected in parallel via a control circuit (6), the upper limit of the charging voltage of the redox flow battery (1) is configured to be higher than the upper limit of the charging voltage of the secondary battery (3), the control circuit (6) includes a voltage sensor (5) that measures a common voltage between the redox flow battery (1) and the secondary battery (3), based on the voltage value of the voltage sensor (5), by opening and closing an electromagnetic switch element (MC2), during charging, the redox flow battery (1) and the secondary battery (3) are configured to be switchable between single connection and parallel connection, A power supply device characterized by comprising a bypass diode (4) whose output current direction from the secondary battery (3) is in the forward direction so as to be connected in parallel with the electromagnetic switch element (MC2). (Claim 2) The power supply device according to claim 1, wherein the input power supply and the battery device are connected to a load via an inverter or a converter. (Claim 3) The control circuit (6) measures a voltage value by the voltage sensor (5) during charging of the redox flow battery (1) and the secondary battery (3), and operates to disconnect the electromagnetic switch element (MC2) when the voltage value reaches the upper limit value of the charging voltage of the secondary battery (3). The power supply device according to claim 1. (Claim 4) The power supply device according to claim 1, 2 or 3, wherein the secondary battery (3) is a lithium ion battery in which a plurality of lithium ion single cells are connected in series. (Claim 5) The power supply device according to claim 4, wherein the lithium ion battery is a lithium iron phosphate ion battery. [Advantages of the Invention]

[0010] According to the present invention, even when a large current discharge is required, the power supply can be stably performed, and a power supply device with good charging efficiency can be provided.

[0011] Further, according to the present invention, by using the secondary battery in combination, it serves as a buffer for the large current discharge of the redox flow battery, and the electric energy of the secondary battery can also be utilized, so that the electric energy of the entire power supply device can be improved. [Brief Description of the Drawings]

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] [Configuration of the Power Supply Device] FIG. 1 is a block diagram showing the configuration of a power supply device. In the example of the power supply device of the present invention shown in FIG. 1, an example is shown in which a power generation device 10 is connected to a battery device including a redox flow battery 1 and a secondary battery 3 via an MPPT (maximum power point tracking controller) 11. The power generation device 10 includes, for example, a solar power generation device, a wind power generation device, etc., and preferably a solar power generation device. The power supply device of this embodiment connects an input power source for supplying power to an inverter 12, connects a battery device between the MPPT 11 and the inverter 12, and outputs an AC output to a load via the inverter 12. In the illustrated example, since an example of a solar power generation device is described, an example of a connection via an inverter is shown as an example in the case of an AC load. However, when connected to a DC load with respect to a DC power source such as a solar power generation device, it may be directly connected to the load, or may be connected via a converter as necessary. The battery device is configured such that the redox flow battery 1 and a secondary battery 3 other than the redox flow battery are connected in parallel via a control circuit 6.

[0015] The secondary battery 3 is a secondary battery other than the redox flow battery, and in this embodiment, is a lithium ion battery such as a lithium iron phosphate ion battery.

[0016] An AC utility power source may be connected to the MPPT 11 together with the power generation device 10 via a rectifier or an AC / DC converter. The current from the power generation device 10 charges the redox flow battery 1 and / or the secondary battery 3 via the MPPT 11. Also, the electromotive force (discharge voltage) of the redox flow battery 1 and / or the secondary battery 3 is output to an external load via the inverter 12 as a common voltage. The common voltage is measured by a voltage sensor 5.

[0017] An electromagnetic on-off switch element MC2 is connected to the secondary battery 3. The electromagnetic on-off switch element MC2 is operated by the control circuit 6 to close (ON) or open (OFF) the connection between the secondary battery 3 and the MPPT 11 and the inverter 12. A bypass diode 4 is connected in parallel to the electromagnetic on-off switch element MC2. The bypass diode 4 has the output current direction from the secondary battery 3 as the forward direction. Examples of the electromagnetic on-off switch element MC2 include an electromagnetic contactor, an electromagnetic switch, etc. As the electromagnetic switch, an electromagnetic contactor equipped with a thermal relay can be exemplified. The electromagnetic contactor is inexpensive as a switch element and can simplify the circuit, and is useful as an element used in the circuit configuration. Electromagnetic on-off switch elements such as electromagnetic contactors and electromagnetic switches may have a time lag in the opening and closing operation. Therefore, by using a bypass diode with the output current direction as the forward direction together with the electromagnetic on-off switch element, the effect of mitigating the sudden change in the electric current flow caused by the time lag in the opening and closing operation of the electromagnetic on-off switch element during discharge can be exerted. Furthermore, the circuit configuration by the combination of the electromagnetic on-off switch element and the bypass diode according to the present embodiment can, in addition to simplifying the circuit, suppress the manufacturing cost of the circuit and further eliminate the time lag in operation.

[0018] An on-off switch element MC1 is connected to the redox flow battery 1. The on-off switch element MC1 may be a switch element similar to the electromagnetic on-off switch element MC1 and is not particularly limited. The on-off switch element MC1 is operated by the control circuit 6 to close (ON) or open (OFF) the connection between the redox flow battery 1 and the MPPT 11 and the inverter 12.

[0019] The control circuit 6 is configured to be able to switch between single connection and parallel connection of the redox flow battery 1 and the secondary battery 3 by opening and closing the two on-off switch elements MC1 and MC2.

[0020] Charging of the battery device is performed by supplying power from various power generation devices 10 such as solar power generation and wind power generation and / or grid power (commercial power supply). The power generation device 10 may incorporate an MPPT 11. Also, the grid power is preferably connected via a rectifier or an AC / DC converter. The power from the power generation device 10 and the grid power is supplied to the positive and negative electrodes of the redox flow battery 1 or the positive and negative electrodes of the secondary battery 3 that constitute the battery device.

[0021] 〔Discharge〕 The redox flow battery 1 drives a pump (not shown) to circulate the electrolytic solution between the battery cell and the electrolytic solution tank 2, discharges the charged electrolytic solution in the battery cell, and supplies power to the outside. To supply power to the outside, it is supplied to the outside (power consumption) via an inverter 12. The connection and disconnection of the redox flow battery 1 and the connection and disconnection of the secondary battery 3 are performed by the control circuit 6.

[0022] When the charged electrolytic solution is discharged in the battery cell, the end of the discharge can be detected (judged) by measuring the state of charge of the electrolytic solution or the voltage of the battery. As a method for measuring the state of charge during discharge, it can be measured by OCV (open circuit voltage).

[0023] Power supply from the secondary battery 3 to the outside is supplied to the outside (power consumption) via an inverter 12. In the above description, since the battery device has DC input and output, a connection example via an inverter is shown for the case of an AC load. However, when connected to a DC load, it may be directly connected to the DC load or may be connected via a converter as required.

[0024] 〔Control by Control Circuit〕 The redox flow battery 1 and the secondary battery 3 have different voltage operating ranges depending on the type and the number of series connections. This power supply device performs control corresponding to the difference in the voltage operating ranges of the redox flow battery 1 and the secondary battery 3. That is, for efficient operation, it is necessary to connect and disconnect between the MPPT 11 of the redox flow battery 1 and the secondary battery 3 and the inverter 12 as needed.

[0025] The control circuit 6 controls the disconnection and connection of the redox flow battery 1 and the secondary battery 3 during charge and discharge by opening and closing the opening / closing switch elements MC1 and MC2. When these batteries are connected simultaneously, they are configured to be connected in parallel with the redox flow battery 1 and the secondary battery 3.

[0026] FIG. 2 is an equivalent circuit diagram showing single-connection control during charging in the control circuit of the power supply device, and FIG. 4 is a sequence diagram showing the control during charging by the control circuit of the power supply device. As shown in FIG. 4, during charging of the redox flow battery 1 and the secondary battery 3, based on the common voltage of the redox flow battery 1 and the secondary battery 3, when the common voltage (input voltage) reaches the upper limit value of the charging voltage of the secondary battery 3, the control circuit 6 operates the opening / closing switch element MC2 to open (disconnect).

[0027] Considering maximizing the capacity of the redox flow battery 1, it is preferable that the discharge lower limit voltage of the secondary battery 3 is equal to or lower than the discharge lower limit voltage of the redox flow battery 1.

[0028] When the charging voltage of the redox flow battery 1 reaches, for example, 62V and the discharge voltage reaches, for example, around 48V, there is almost no remaining capacity. When the charging voltage of the secondary battery 3 reaches, for example, 56V and the discharge voltage reaches, for example, around 47V, there is almost no remaining capacity.

[0029] To make the most of the capacities of the redox flow battery 1 and the secondary battery 3, as shown in Fig. 4, when the common voltage (input voltage) reaches 56V, the secondary battery 3 is disconnected (the switching element MC2 is opened), and thereafter, charging continues with the redox flow battery 1 alone (the closing of the switching element MC1 is continued).

[0030] To prevent overcharging of the redox flow battery 1, after the charging voltage reaches the upper limit and switches to constant voltage charging, when the current (I RfB) to the redox flow battery 1 decreases, the charging of the redox flow battery 1 is stopped (the switching element MC1 is opened). The feature of this power supply device is not to manage the states of the redox flow battery 1 and the secondary battery 3 individually, but in principle to judge it only by the common voltage (input voltage), and to connect and disconnect the redox flow battery 1 and the secondary battery 3. By doing so, the monitor cell mainly used in the redox flow battery 1 becomes unnecessary, and the structure becomes simple, so the cost can be reduced.

[0031] However, as an issue in managing during charging only by the common voltage (input voltage), there are stabilization of full charge and prevention of overcharging of the redox flow battery 1. Since the redox flow battery 1 has a large internal resistance, the fully charged state varies greatly depending on the magnitude of the charging current (I RfB) at that time. When charging with a large current, it is easy to reach the upper limit of the voltage operating range, and if it is judged as fully charged only by voltage detection of the common voltage (input voltage), there is a possibility that the charge amount is not sufficient in reality. Conversely, if the charging current (I RfB) is too small, there is a risk of overcharging before reaching the upper limit of the voltage operating range.

[0032] Therefore, in this power supply device, when the common voltage (input voltage) does not exceed the charging upper limit voltage (for example, 62V) of the redox flow battery 1, it shifts to constant voltage charging, and when the charging current (I RfB) becomes less than or equal to a predetermined value (for example, 20A or less), the redox flow battery 1 is disconnected as fully charged (the switching element MC1 is opened).

[0033] FIG. 3 is an equivalent circuit diagram showing bypass diode control in which the output current direction during discharge in the control circuit of the power supply device is the forward direction, and FIG. 5 is a sequence diagram showing the control during discharge by the control circuit of the power supply device. When charging has progressed to a certain extent, as shown in FIG. 5, discharging is started with only the charge of the redox flow battery 1 connected. When the discharge progresses and drops to a predetermined voltage (for example, 54 V), the secondary battery 3 is reconnected. However, if the load current suddenly increases before this, the voltage of the redox flow battery 1 drops rapidly, and the connection operation of the secondary battery 3 (operation of the open / close switch element MC2) may not be in time, and there is a risk that the inverter 12 will stop. Since the redox flow battery 1 has a high internal resistance, if a large current is discharged, the input voltage to the inverter 12 may drop below the allowable voltage range of the inverter.

[0034] As a countermeasure, in the power supply device of this aspect, a bypass diode 4 is provided to create a bypass path, thereby compensating for the voltage drop of the redox flow battery 1. That is, in this power supply device, when the electromotive force of the redox flow battery 1 falls below the electromotive force of the secondary battery 3, the secondary battery 3 covers it and the voltage drop can be suppressed.

[0035] In this way, in this power supply device, when the input voltage to the inverter 12 drops below the allowable voltage range due to the supply of a large current from the redox flow battery 1 to the outside, power is supplied from the secondary battery 3, and the drop width of the input voltage to the inverter 12 becomes smaller. Examples of cases where a large current supply is required include when starting a large cell motor.

[0036] 〔Configuration of Redox Flow Battery〕 The power supply device of the present invention functions to supply power to power-consuming facilities such as lighting, prime movers, and electronic circuits by means of a redox flow battery 1. The redox flow battery 1 is composed of battery cells and an electrolyte tank 2 including a positive electrode electrolyte tank and a negative electrode electrolyte tank (in FIG. 1, the positive electrode electrolyte tank and the negative electrode electrolyte tank are simply represented as one electrolyte tank 2). The battery cells and the electrolyte tank 2 are connected by pipes and function as the redox flow battery 1. The corresponding electrolyte is contained in the electrolyte tank 2.

[0037] The battery cells include a positive electrode cell having a built-in positive electrode and capable of circulating a positive electrode electrolyte containing vanadium as an active material, and a negative electrode cell having a built-in negative electrode and capable of circulating a negative electrode electrolyte containing vanadium as an active material. The positive electrode cell and the negative electrode cell are separated by a diaphragm that allows a predetermined ion to pass through (in FIG. 1, these positive electrode cells and negative electrode cells are represented in a simplified manner).

[0038] Also, the battery cells are configured such that the inflow and outflow of the positive electrode electrolyte to the positive electrode cell and the inflow and outflow of the negative electrode electrolyte to the negative electrode cell are possible. The battery cells are configured by stacking a plurality of cells. Here, the output of the redox flow battery 1 is determined by the number of single cells (cells), and the amount of electric power is determined by the capacity stored in the electrolyte. For example, when 40 cells of the redox flow battery 1 are used in a cell stack of one stack, the electromotive force is about 40 to 62V. However, it is not limited to this, and the number of cells and stacks necessary to make the output of the battery stable and supplyable may be provided.

[0039] Vanadium is preferably used as the active material contained in the positive electrode electrolyte of the positive electrode electrolyte tank and the negative electrode electrolyte of the negative electrode electrolyte tank.

[0040] The positive electrode electrolyte tank and the negative electrode electrolyte tank increase in tank capacity as the supply amount of the electric power increases. For example, although it varies depending on the active material concentration of the electrolytic solution, when the amount of the electrolytic solution in the tank is 500 L (total of the positive and negative electrode solutions), it is about 10.0 kWh, and when it is 700 L, it is about 13.5 kWh. In the present embodiment, it is preferable to use a tank with a necessary tank capacity according to the required amount of electric power.

[0041] The positive electrode electrolytic solution tank is configured to allow the entry and exit of the positive electrode electrolytic solution, and the negative electrode electrolytic solution tank is configured to allow the entry and exit of the negative electrode electrolytic solution.

[0042] As a method for measuring the depth of charge, the degree of charge can be confirmed by measuring the OCV (open circuit voltage). It is possible to measure by stopping the charge and discharge of the redox flow battery, or a separate cell for measurement may be provided. A measuring instrument (not shown) capable of measuring the depth of charge can be provided at an arbitrary position.

[0043] The redox flow battery 1 in the present aspect is equipped with a positive electrode liquid pump (not shown) that introduces the positive electrode electrolytic solution into the positive electrode cell and discharges it from the positive electrode cell, and a negative electrode liquid pump (not shown) that introduces the negative electrode electrolytic solution into the negative electrode cell and discharges it from the negative electrode cell.

[0044] The piping between the battery cell and the electrolytic solution tank 2 is connected so that the supply of the positive electrode electrolytic solution from the positive electrode electrolytic solution tank to the positive electrode cell and the supply of the negative electrode electrolytic solution from the negative electrode electrolytic solution tank to the negative electrode cell are possible. Also, the piping is connected so that the return of the positive electrode electrolytic solution from the positive electrode cell to the positive electrode electrolytic solution tank and the return of the negative electrode electrolytic solution from the negative electrode cell to the negative electrode electrolytic solution tank are possible.

[0045] Note that the electrolytic solution contains sulfuric acid and is acidic, and there is a strong risk of metal corrosion. Therefore, the piping through which the electrolytic solution passes is preferably made of a corrosion-resistant resin. Also, it is preferable that a reinforcing mesh body is loaded inside the resin in order to prevent breakage and the like.

[0046] As the redox flow battery 1 in this embodiment, for example, those with an output of 4 to 6 kW, an electromotive force of 40 V to 62 V, and an electrolyte volume of about 300 L for each of the positive and negative electrodes can be used. The redox flow battery has the characteristic of good current acceptance.

[0047] The redox flow battery is used in a form called a cell stack in which battery cells are used as the minimum unit and are stacked alone or in multiple layers. An electrolyte containing vanadium as an active material is supplied to the battery cells for charge and discharge. The charge and discharge reactions in the positive and negative electrodes are as follows. Positive electrode cell Charge: V 4+ →V 5 ++e - Discharge: V 5+ +e - →V 4+ Negative electrode cell Charge: V 3+ +e - →V 2+ Discharge: V 2+ →V 3+ +e -

[0048] (Positive electrode · Negative electrode) As the positive electrode and the negative electrode, known electrodes can be used and are not particularly limited. However, they only provide a site where a redox reaction occurs when vanadium in the electrolyte passes through the battery cell and do not react themselves. They have a structure and form with excellent permeability to the electrolyte, preferably a large surface area as much as possible, and low electrical resistance. Furthermore, from the viewpoint of activating the redox reaction, it is preferably excellent in affinity with the electrolyte (aqueous solution). Further, from the viewpoint of not causing the decomposition of water, which is a side reaction, it is preferable that the hydrogen overvoltage and the oxygen overvoltage are large. For example, carbon materials such as carbon felt or those graphitized, or those obtained by applying a noble metal plating or a carbon coating to a mesh-shaped titanium or zirconium substrate can be mentioned.

[0049] (Separator) As the separator, a known separator can be used and is not particularly limited. For example, an ion exchange membrane made of an organic polymer is preferable, and either a cation exchange membrane or an anion exchange membrane can be used.

[0050] (Electrolyte) The positive electrode electrolyte contains one or both of tetravalent and pentavalent vanadium compounds. The positive electrode electrolyte may contain additives such as oxoacids such as nitric acid, protective colloid agents, and complexing agents, which are conventionally known, in order to prevent the precipitation of precipitates.

[0051] The negative electrode electrolyte contains one or both of divalent and trivalent vanadium compounds. The negative electrode electrolyte may contain additives such as oxoacids such as nitric acid, protective colloid agents, and complexing agents, which are conventionally known, in order to prevent the precipitation of precipitates.

[0052] Generally, the vanadium electrolyte is prepared by dissolving a vanadium sulfate oxide salt in an aqueous sulfuric acid solution to adjust a tetravalent vanadium ion solution, and then electrolyzing the vanadium ion solution to obtain vanadium ion solutions with different valences. For example, in the positive electrode electrolyte, a solution containing pentavalent vanadium ions (VO2 2+ ) as the positive electrode active material is adjusted by the oxidation reaction of tetravalent vanadium ions (VO + ). In the negative electrode electrolyte, a solution containing divalent vanadium ions (V 3+ ) as the negative electrode active material is adjusted by the reduction reaction of trivalent vanadium ions (V 2+ ).

[0053] The redox flow battery 1 of this embodiment configured as described above is configured such that the upper limit of the charging voltage is higher than the upper limit of the charging voltage of the secondary battery 3.

[0054] 〔Configuration of Secondary Battery〕 The secondary battery 3 includes, for example, a lead storage battery, a nickel-hydrogen storage battery, a lithium-ion battery, etc. It is preferable that the secondary battery 3 has a lower upper limit voltage than the redox flow battery, and it is preferable to use a lithium-ion battery having a large output per unit weight and volume, that is, a large output density.

[0055] Furthermore, examples of the lithium-ion battery include a cobalt-based lithium-ion battery, a lithium iron phosphate ion battery, etc. From the viewpoint of safety, it is preferable to use a lithium iron phosphate ion battery. Hereinafter, an example in which a lithium iron phosphate ion battery is used for the secondary battery 3 will be described.

[0056] The lithium iron phosphate ion battery can supply power together with the redox flow battery 1 when a large current supply is required. Also, it can be used in place of the redox flow battery 1 when the redox flow battery 1 is not charged.

[0057] For the lithium iron phosphate ion battery, for example, when the battery is composed of 16 single cells (cells) connected in series, a battery with an electromotive voltage of 48V to 56V and a capacity of 50Ah can be used. It is not limited to this, and regarding the electromotive force and power capacity of the lithium iron phosphate ion battery, they can be changed according to the specifications of the redox flow battery, which also facilitates control.

[0058] The lithium iron phosphate ion battery is composed of a plurality of single cells (cells) connected in series, and is provided with a cell balancer (not shown) for adjusting the capacity balance of each single cell.

[0059] Since there is no oxygen detachment from the positive electrode material in the lithium iron phosphate ion battery, it does not burn from the location where an internal short circuit occurs and is safe. Also, in the lithium iron phosphate ion battery, the short-circuited part undergoes a chemical reaction and becomes an insulator, so it does not spread to the surroundings and is safe.

[0060] 〔Charging〕 Charging the electrolyte tank 2 of the redox flow battery 1 is performed by applying a voltage between the positive and negative electrodes and circulating the positive and negative electrolytes between the battery cell and the electrolyte tank 2 by means of a pump. Also, the secondary battery 3 is charged by applying a voltage between the positive and negative electrodes.

Explanation of symbols

[0061] 1 Redox flow battery 2 Electrolyte tank 3 Secondary battery 4 Bypass diode 5 Voltage sensor 6 Control circuit 10 Power generation device 11 MPPT (Maximum Power Point Tracker) 12 Inverter

Claims

1. In a power supply device in which a battery device is connected between an input power supply that supplies power and a load, the battery device is configured such that a redox flow battery (1) and a secondary battery (3) other than the redox flow battery are connected in parallel via a control circuit (6), the upper limit of the charging voltage of the redox flow battery (1) is configured to be higher than the upper limit of the charging voltage of the secondary battery (3), the control circuit (6) includes a voltage sensor (5) that measures a common voltage between the redox flow battery (1) and the secondary battery (3), based on the voltage value of the voltage sensor (5), by opening and closing an electromagnetic switching element (MC2), during charging, the redox flow battery (1) and the secondary battery (3) are configured to be switchable between single connection and parallel connection, A power supply device, characterized in that it includes a bypass diode (4) whose output current direction from the secondary battery (3) is in the forward direction so as to be connected in parallel with the electromagnetic switching element (MC2).

2. The power supply device according to claim 1, characterized in that the input power supply and the battery device are connected to a load via an inverter or a converter.

3. The control circuit (6) measures a voltage value by the voltage sensor (5) during charging of the redox flow battery (1) and the secondary battery (3), and when the voltage value reaches the upper limit value of the charging voltage of the secondary battery (3), the electromagnetic switching element (MC2) is operated to be disconnected. The power supply device according to claim 1.

4. The power supply device according to claim 1, 2 or 3, characterized in that the secondary battery (3) is a lithium ion battery in which a plurality of lithium ion single cells are connected in series.

5. The power supply device according to claim 4, characterized in that the lithium ion battery is a lithium iron phosphate ion battery.

Images