Power supply unit for electrolytic cells

Abstract

Provided is an electrolytic cell power supply device that comprises: a first converter that converts AC power supplied from a power grid into DC power; a power storage element that performs power storage of the DC power outputted from the first converter; a second converter that converts the DC power stored in the power storage element and supplies the converted power to an electrolytic cell; and a control device that controls operation of the first converter and the second converter. The control device has an anti-corrosion driving mode that, when a power grid outage occurs and on the basis of the DC power stored in the power storage element, controls the operation of the second converter so as to suppress generation, in the electrolytic cell, of a reverse current, which is a current component flowing in the direction opposite to the normal electrolysis direction. Due to this configuration, an electrolytic cell power supply device is provided that enables, using a simpler configuration, suppression of reverse current generation.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a power supply device for an electrolytic cell. [Background technology]

[0002] There is an electrolytic cell power supply device that causes an electrolytic cell to perform electrolysis by supplying DC power between the anode and cathode of the electrolytic cell. The electrolytic cell power supply device is connected to an AC power system, converts the AC power supplied from the power system into DC power suitable for the electrolytic cell, and supplies the converted DC power between the anode and cathode of the electrolytic cell. The electrolytic cell performs electrolysis in response to the supply of DC power from the electrolytic cell power supply device, thereby producing products such as hydrogen.

[0003] In such electrolytic cell power supply devices, if a power outage occurs in the power grid and the supply of DC power to the electrolytic cell is stopped, a reverse current (current in the opposite direction from the electrodes in the electrolytic cell) may flow in the electrolytic cell, which is a current in the opposite direction to normal electrolysis. The occurrence of such a reverse current can cause deterioration of the electrolytic cell. For example, it may oxidize the cathode of the electrolytic cell.

[0004] For this reason, a corrosion prevention power supply equipped with a battery or the like is provided separately from the power supply device for the electrolytic cell, and power is supplied to the electrolytic cell from the corrosion prevention power supply in the event of a power outage, thereby suppressing the occurrence of reverse current and the resulting deterioration of the electrolytic cell.

[0005] However, a configuration that requires a separate anticorrosion power supply increases the number of components and complicates the configuration of the equipment. For example, there are concerns that this may lead to an increase in the size and cost of the equipment. For this reason, it is desirable to have a power supply device for an electrolytic cell that can suppress the occurrence of reverse current with a simpler configuration. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5797621 Summary of the Invention [Problem to be solved by the invention]

[0007] An embodiment of the present invention provides a power supply device for an electrolytic cell that can suppress the occurrence of reverse current with a simpler configuration. [Means for solving the problem]

[0008] According to an embodiment of the present invention, there is provided a power supply device for an electrolytic cell that causes electrolysis in an electrolytic cell by supplying DC power between an anode and a cathode of the electrolytic cell, the power supply device including: a first converter that converts AC power supplied from a power grid into DC power; , converting input DC power into another DC power The second converter and a storage element between the first converter and the second converter, the storage element being connected in parallel to the first converter and the second converter; and a control device that controls operation of the first converter and the second converter, wherein the control device has a normal operation mode in which, when the power system is operating normally, the operation of the first converter and the second converter is controlled to supply DC power for electrolysis to the electrolytic cell based on AC power supplied from the power system, and a corrosion prevention operation mode in which, when the power system is operating normally, the operation of the second converter is controlled to supply DC power to the electrolytic cell that is smaller than the DC power supplied to the electrolytic cell in the normal operation mode based on DC power stored in the storage element, thereby suppressing the generation of a reverse current, which is a current component that flows in the opposite direction to normal electrolysis in the electrolytic cell. The second converter has a plurality of conversion circuits connected in parallel, and the control device operates each of the plurality of conversion circuits in the normal operation mode, and operates only a part of the plurality of conversion circuits in the anticorrosion operation mode. A power supply for the electrolytic cell is provided. [Effects of the Invention]

[0009] According to an embodiment of the present invention, a power supply device for an electrolytic cell is provided that can suppress the occurrence of reverse current with a simpler configuration. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a first embodiment. [Figure 2]FIG. 2 is a block diagram schematically illustrating an example of a conversion circuit. [Figure 3] FIG. 10 is a block diagram schematically illustrating a first converter according to a second embodiment. [Figure 4] 10 is a graph schematically showing an example of the operation of the electrolytic cell power supply device according to the third embodiment. [Figure 5] FIG. 10 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a fourth embodiment. [Figure 6] FIG. 10 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a fifth embodiment. [Figure 7] FIG. 10 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a sixth embodiment. [Figure 8] 8(a) and 8(b) are timing charts that schematically show an example of the operation of the power supply device for an electrolytic cell according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0012] (First embodiment) FIG. 1 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a first embodiment. As shown in Figure 1, the electrolytic cell power supply device 10 comprises a first converter 11, a second converter 12, a storage element 14, and a control device 16. The electrolytic cell power supply device 10 is used in an electrolytic cell 2. The electrolytic cell 2 has an anode 2a and a cathode 2b. The electrolytic cell power supply device 10 supplies DC power between the anode 2a and the cathode 2b of the electrolytic cell 2, causing the electrolytic cell 2 to perform electrolysis.

[0013] The electrolytic cell 2 performs electrolysis in response to the supply of DC power from the electrolytic cell power supply device 10, thereby producing products such as hydrogen. The electrolytic cell 2 may further include, for example, an ion exchange membrane (diaphragm) disposed between the anode and the cathode. The electrolytic cell 2 may have any configuration that includes at least an anode 2a and a cathode 2b and that allows electrolysis of an electrolyte solution or the like to be performed by supplying DC power between the anode 2a and the cathode 2b.

[0014] The electrolytic cell power supply device 10 is connected to the electrolytic cell 2 and also to a power system 4. The power system 4 is an AC power system. The electrolytic cell power supply device 10 is connected to the power system 4, for example, via a transformer 6. The power of the power system 4 is, for example, three-phase AC power. However, the power of the power system 4 is not limited to three-phase AC power, and may be single-phase AC power, for example.

[0015] The first converter 11 is connected to the power system 4. The first converter 11 is connected to the power system 4 via, for example, a transformer 6. The first converter 11 converts AC power supplied from the power system 4 into DC power. The first converter 11 is, for example, an AC-DC converter circuit.

[0016] The storage element 14 stores the DC power output from the first converter 11. The storage element 14 is, for example, a capacitor or a secondary battery. The storage element 14 may be any element capable of storing the DC power output from the first converter 11.

[0017] The second converter 12 converts the DC power stored in the storage element 14 into another DC power appropriate for the electrolytic cell 2, and supplies the converted DC power between the anode 2a and cathode 2b of the electrolytic cell 2. The second converter 12 is, for example, a DC-DC converter circuit. The second converter 12 has, for example, a plurality of conversion circuits 20 connected in parallel.

[0018] FIG. 2 is a block diagram schematically illustrating an example of a conversion circuit. As shown in FIG. 2, each of the multiple conversion circuits 20 includes, for example, a pair of input terminals 20a and 20b, a pair of output terminals 20c and 20d, switching elements 21 and 22, rectifying elements 23 and 24, a capacitor 25, and a reactor 26.

[0019] One input terminal 20a is connected to the high potential side terminal of the storage element 14. The other input terminal 20b is connected to the low potential side terminal of the storage element 14. As a result, the DC power stored in the storage element 14 is input to the conversion circuit 20 via the pair of input terminals 20a, 20b.

[0020] The switching elements 21 and 22 have a pair of main terminals and a control terminal. The switching elements 21 and 22 have an on state and an off state. The on state is a state in which a current flows between the pair of main terminals. The off state is a state in which the flow of current between the pair of main terminals is blocked. Each of the switching elements 21 and 22 switches between the on state and the off state depending on the voltage between the pair of main terminals and the voltage of the control terminal. Note that the off state is not limited to a state in which no current flows between the pair of main terminals, but may also be a state in which a weak current flows between the pair of main terminals within a range that does not affect the operation of the conversion circuit 20.

[0021] The switching elements 21 and 22 are, for example, self-excited semiconductor switching elements such as IGBTs and MOSFETs. However, the switching elements 21 and 22 are not limited to this and may be any elements that can be arbitrarily switched between an on state and an off state.

[0022] One main terminal of switching element 21 is electrically connected to input terminal 20a. The other main terminal of switching element 21 is electrically connected to one main terminal of switching element 22. Switching element 22 is connected in series with switching element 21. The other main terminal of switching element 22 is electrically connected to input terminal 20b. Switching elements 21 and 22 are connected in series between input terminals 20a and 20b. In other words, switching element 21 is provided between input terminal 20a and switching element 22, and switching element 22 is provided between switching element 21 and input terminal 20b.

[0023] The rectifying element 23 is connected in anti-parallel to the switching element 21. The rectifying element 24 is connected in anti-parallel to the switching element 22. The rectifying elements 23, 24 are, for example, diodes. The anodes of the rectifying elements 23, 24 are electrically connected to the low-potential side main terminals of the switching elements 21, 22, and the cathodes of the rectifying elements 23, 24 are electrically connected to the high-potential side main terminals of the switching elements 21, 22. The direction of the current flowing through the rectifying elements 23, 24 (direction of rectification) is opposite to the direction of the current flowing through the switching elements 21, 22.

[0024] The capacitor 25 is provided between the input terminals 20a and 20b and serves to suppress fluctuations in the DC power input from the storage element 14 to the conversion circuit 20, for example.

[0025] One end of reactor 26 is electrically connected to the connection point of switching elements 21 and 22. The other end of reactor 26 is electrically connected to one output terminal 20c. The other output terminal 20d is electrically connected to input terminal 20b.

[0026] Each of the multiple conversion circuits 20 has switching elements 21, 22, and performs DC power conversion by switching the switching elements 21, 22. The conversion circuit 20 is, for example, a step-down chopper circuit. The conversion circuit 20 converts the DC power stored in the storage element 14 into another DC power suitable for the electrolytic cell 2, for example, by switching the switching element 21.

[0027] The second converter 12 has a plurality of conversion circuits 20 connected in parallel. This makes it possible to accommodate large DC power while suppressing an increase in the allowable values ​​of current and voltage required for the switching elements 21 and 22. The conversion circuit 20 also has, for example, a plurality of switching elements 21 connected in parallel, a plurality of switching elements 22 connected in parallel, a plurality of rectifying elements 23 connected in anti-parallel to each of the plurality of switching elements 21, and a plurality of rectifying elements 24 connected in anti-parallel to each of the plurality of switching elements 22. This makes it possible to further suppress an increase in the allowable values ​​of current and voltage required for the switching elements 21 and 22.

[0028] However, the configuration of the conversion circuit 20 and the configuration of the second converter 12 are not limited to those described above, and any configuration may be used as long as it is possible to convert the DC power stored in the storage element 14 into another DC power suitable for the electrolytic cell 2. The number of parallel connections in the conversion circuit 20 and the number of parallel connections of each of the switching elements 21, 22 may be set appropriately depending on, for example, the magnitude of the DC power to be handled.

[0029] The control device 16 controls the operations of the first converter 11 and the second converter 12. The control device 16 controls the operation of the second converter 12 by, for example, generating a plurality of control signals corresponding to the switching elements 21, 22 of the plurality of conversion circuits 20, inputting the control signals to the control terminals of the switching elements 21, 22, and controlling the switching of the switching elements 21, 22.

[0030] The control device 16 has a normal operation mode and a corrosion prevention operation mode. The normal operation mode is a mode in which, when the power grid 4 is operating normally, the operation of the first converter 11 and the second converter 12 is controlled so that DC power for electrolysis is supplied to the electrolytic cell 2 based on AC power supplied from the power grid 4.

[0031] The control device 16 receives command values ​​for the DC current and DC voltage to be supplied to the electrolytic cell 2 from, for example, a higher-level controller, and controls the operation of the first converter 11 and the second converter 12 so as to output a DC current and a DC voltage according to the received command values. The command values ​​change, for example, depending on the amount of product produced in the electrolytic cell 2. This makes it possible to produce the required amount of product in the electrolytic cell 2 based on the supply of DC power from the electrolytic cell power supply device 10 (second converter 12).

[0032] The anticorrosion operation mode is a mode in which, during a power outage in the power grid 4, the operation of the second converter 12 is controlled to supply to the electrolytic cell 2 DC power that is smaller than the DC power supplied to the electrolytic cell 2 in the normal operation mode, based on the DC power stored in the storage element 14, thereby suppressing the generation of a reverse current, which is a current that flows in the opposite direction to normal electrolysis in the electrolytic cell 2. Note that, during a power outage in the power grid 4, the power supply for the control device 16 may be supplied from the storage element 14 or from another power source such as a battery. The control device 16 may, for example, have an auxiliary power source such as a battery to continue operation during a power outage in the power grid 4.

[0033] In the anticorrosion operation mode, the magnitude of the DC current supplied from the second converter 12 to the electrolytic cell 2 is set, for example, to about 1% (e.g., 0.5% to 5%) of the maximum magnitude of the DC current supplied from the second converter 12 to the electrolytic cell 2 in the normal operation mode. The anticorrosion operation mode may be, for example, a state in which the magnitude of the DC current supplied by the electrolytic cell 2 is set as close to zero as possible, while a DC voltage of a predetermined magnitude is applied between the anode 2a and cathode 2b of the electrolytic cell 2.

[0034] In the corrosion prevention operation mode, the control device 16, for example, stops the operation of the first converter 11. The control device 16 stops the operation of the first converter 11, for example, by stopping the input of a control signal to the first converter 11. The control device 16 stops the operation of the first converter 11 by performing a so-called gate block.

[0035] The electrolytic cell power supply device 10 further includes, for example, a measuring instrument (not shown). The measuring instrument measures, for example, the AC current and AC voltage of the power grid 4 and inputs the measurement results to the control device 16. In other words, the measuring instrument is a measuring instrument for detecting a power outage in the power grid 4.

[0036] In the normal operation mode, the control device 16 detects a power outage in the power grid 4 based on the measurement results of the measuring instruments, and switches from the normal operation mode to the anticorrosion operation mode in response to the detection of the power outage. In the anticorrosion operation mode, the control device 16 detects recovery from a power outage in the power grid 4 based on the measurement results of the measuring instruments, and switches from the anticorrosion operation mode to the normal operation mode in response to the detection of recovery from the power outage.

[0037] The method by which the control device 16 detects a power outage in the power system 4 and a recovery from a power outage in the power system 4 is not limited to the above. The control device 16 may detect a power outage and a recovery from a power outage, for example, based on a signal input from a higher-level controller. The method by which the control device 16 detects a power outage in the power system 4 and a recovery from a power outage in the power system 4 may be any method that can appropriately detect a power outage in the power system 4 and a recovery from a power outage.

[0038] Furthermore, in this specification, the term "power outage" is not limited to a drop in the voltage of the power grid 4 that continues for a predetermined period of time or longer, but also includes momentary power outages and momentary voltage drops in which the voltage of the power grid 4 temporarily drops for a short period of time, such as less than one minute.

[0039] As described above, in the electrolytic cell power supply device 10 according to this embodiment, the control device 16 has a normal operation mode and an anticorrosion operation mode, and switches from the normal operation mode to the anticorrosion operation mode in response to detection of a power outage.

[0040] As a result, electrolytic cell power supply device 10 can prevent the configuration of the equipment related to electrolytic cell 2 from becoming more complex than, for example, a case in which a separate anti-corrosion power supply is provided for electrolytic cell power supply device 10 and power is supplied to electrolytic cell 2 from the anti-corrosion power supply in the event of a power outage. For example, it can prevent the equipment from becoming larger and costs from increasing. Electrolytic cell power supply device 10 can prevent the occurrence of reverse current with a simpler configuration.

[0041] Furthermore, in the electrolytic cell power supply device 10, the operation of the first converter 11 is stopped in the anticorrosion operation mode. This prevents the DC power stored in the storage element 14 from being consumed by the operation of the first converter 11. Therefore, the DC power stored in the storage element 14 allows operation in the anticorrosion operation mode to continue for a longer period of time, and deterioration of the electrolytic cell 2 due to the occurrence of reverse current can be prevented for a longer period of time.

[0042] (Second embodiment) FIG. 3 is a block diagram schematically illustrating a first converter according to the second embodiment. 3, the first converter 11 has a plurality of full-bridge-connected switching elements 30 and a plurality of rectifying elements 32 connected in anti-parallel to each of the plurality of switching elements 30. In the following embodiments, components that are substantially the same in function and configuration as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0043] In this example, the first converter 11 has six switching elements 30 connected in a three-phase full bridge configuration, and six rectifying elements 32 connected in anti-parallel to each of the six switching elements 30.

[0044] The first converter 11 converts AC power supplied from the power grid 4 into DC power by rectifying the power using a plurality of rectifying elements 32. The plurality of rectifying elements 32 are, for example, diodes. The first converter 11 converts AC power supplied from the power grid 4 into DC power using, for example, a diode bridge circuit.

[0045] Furthermore, the first converter 11 converts the DC power stored in the storage element 14 into AC power by switching the multiple switching elements 30. Thus, in this example, the first converter 11 has a function of converting AC power supplied from the power grid 4 into DC power and supplying it to the storage element 14, and a function of converting the DC power stored in the storage element 14 into AC power and supplying it to the power grid 4. In other words, the first converter 11 has a bidirectional conversion function of converting AC power to DC power and converting DC power to AC power.

[0046] In the corrosion prevention operation mode, the control device 16 controls the operation of the first converter 11 so as to supply only reactive power to the power grid 4 based on the DC power stored in the storage element 14.

[0047] Thus, in this example, the first converter 11 has a bidirectional conversion function, and the control device 16 controls the operation of the first converter 11 so that it supplies only reactive power to the power grid 4 in the corrosion prevention operation mode. This makes it possible to contribute to maintaining the voltage of the power grid 4 when a power outage occurs in the power grid 4.

[0048] As described above in relation to the first embodiment, if the operation of the first converter 11 is stopped in the anticorrosion operation mode, deterioration of the electrolytic cell 2 can be suppressed for a longer period of time. Whether to stop the operation of the first converter 11 in the anticorrosion operation mode or to operate the first converter 11 so as to supply only reactive power may be selected as appropriate depending on the capacity of the storage element 14, the specifications of the power system 4, etc. For example, it may be possible to switch between a mode in which the operation of the first converter 11 is stopped and a mode in which the first converter 11 is operated so as to supply only reactive power based on a signal input from the outside.

[0049] (Third embodiment) FIG. 4 is a graph schematically showing an example of the operation of the power supply device for an electrolytic cell according to the third embodiment. FIG. 4 schematically shows an example of the effective value of the AC voltage (receiving voltage) supplied from the power grid 4, the period of the anticorrosion operation mode, and the command value of the DC current (output current) supplied to the electrolytic cell 2.

[0050] 4, for example, when the power system 4 is operating normally in a normal operation mode, the control device 16 detects a power outage in the power system 4 based on the power receiving voltage of the power system 4 measured by a measuring instrument (not shown). The control device 16 detects a power outage in the power system 4 when the power receiving voltage of the power system 4 becomes equal to or lower than a power outage determination level VL1.

[0051] In response to detecting a power outage in the power grid 4, the control device 16 switches from the normal operation mode to the anticorrosion operation mode. When the control device 16 switches to the anticorrosion operation mode, it gradually reduces the magnitude of the DC power supplied to the electrolytic cell 2. The control device 16 gradually reduces the magnitude of the DC power supplied to the electrolytic cell 2, for example, by gradually reducing the command value for the DC current supplied to the electrolytic cell 2 from the level in the normal operation mode to the level in the anticorrosion operation mode. In other words, the control device 16 gradually reduces the magnitude of the DC current supplied to the electrolytic cell 2.

[0052] When operating in the corrosion prevention operation mode, the control device 16 detects the restoration of the power grid 4 from a power outage based on the power receiving voltage of the power grid 4 measured by a measuring instrument (not shown). The control device 16 detects the restoration of the power grid 4 from a power outage when the power receiving voltage of the power grid 4 becomes equal to or higher than a restoration determination level VL2. The restoration determination level VL2 is set to, for example, a value greater than the power outage determination level VL1. This makes it possible to prevent the control device 16 from detecting the occurrence of a power outage immediately after detecting the restoration of the power outage, for example.

[0053] In response to detecting the restoration of power grid 4 from a power outage, control device 16 switches from anticorrosion operation mode to normal operation mode. When control device 16 switches to normal operation mode, it gradually increases the magnitude of the DC power supplied to electrolytic cell 2. Control device 16 gradually increases the magnitude of the DC power supplied to electrolytic cell 2, for example, by gradually increasing the command value for the DC current supplied to electrolytic cell 2 from the level of anticorrosion operation mode to the level of normal operation mode. In other words, control device 16 gradually increases the magnitude of the DC current supplied to electrolytic cell 2.

[0054] In this example, when switching from the normal operation mode to the anticorrosion operation mode, and when switching from the anticorrosion operation mode to the normal operation mode, the control device 16 gradually changes the magnitude of the DC power supplied to the electrolytic cell 2. This makes it possible to suppress, for example, deterioration of the electrolytic cell 2 due to a sudden change in the DC power (direct current) supplied to the electrolytic cell 2.

[0055] As described above, when the magnitude of the DC power supplied to the electrolytic cell 2 is gradually changed, the capacity of the storage element 14 (the magnitude of the DC power stored in the storage element 14) is determined according to the energy consumption required to gradually change the magnitude of the DC power.

[0056] In Figure 4, the magnitude of the DC power supplied to the electrolytic cell 2 is gradually changed by continuously changing the DC current command value at a constant gradient. The DC current command value is not limited to a continuous change, but may be changed in steps, for example. Furthermore, the control device 16 may gradually change the magnitude of the DC power supplied to the electrolytic cell 2, for example, by gradually changing the DC voltage command value. The method for gradually changing the magnitude of the DC power supplied to the electrolytic cell 2 is not limited to the above, and any method that can gradually change the magnitude of the DC power supplied to the electrolytic cell 2 may be used.

[0057] (Fourth embodiment) FIG. 5 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a fourth embodiment. As shown in FIG. 5, the electrolytic cell power supply device 10a includes an emergency generator 40, a rectifier 42, switches 44 and 46, and a transformer 48.

[0058] The emergency generator 40 is a generator for charging the storage element 14 in the event of a power outage in the power grid 4. The power generated by the emergency generator 40 is, for example, AC power. The emergency generator 40 is, for example, an AC generator. The emergency generator 40 is, for example, an engine-driven generator that generates power using fuel such as gasoline or gas. The start and stop of the emergency generator 40 is controlled, for example, by the control device 16.

[0059] The rectifier 42 is a rectifier for initially charging the storage element 14 based on AC power supplied from the power grid 4. The rectifier 42 is, for example, a diode bridge circuit. The rectifier 42, for example, full-wave rectifies the AC power supplied from the power grid 4 and supplies the rectified power to the storage element 14, thereby initially charging the storage element 14. However, the configuration of the rectifier 42 is not limited to the above, and any configuration that allows initially charging the storage element 14 based on AC power supplied from the power grid 4 may be used.

[0060] The rectifier 42 is connected to the power grid 4 via, for example, a switch 44 and a transformer 48. The opening and closing of the switch 44 is controlled, for example, by the control device 16. When the voltage of the storage element 14 is extremely low, for example, at the start of operation of the electrolytic cell power supply device 10a, the control device 16 closes the switch 44 and charges the storage element 14 via the rectifier 42 to a level at which the first converter 11 and the second converter 12 can operate normally. After charging the storage element 14 to a level at which the first converter 11 and the second converter 12 can operate normally, for example, the control device 16 opens the switch 44 and starts the operation of the first converter 11 and the second converter 12.

[0061] The emergency generator 40 is connected to the storage element 14 via a rectifier 42. The emergency generator 40 generates AC power and supplies the generated AC power to the rectifier 42, thereby charging the storage element 14 via the rectifier 42.

[0062] The switch 46 is provided between the emergency generator 40 and the rectifier 42. The emergency generator 40 is connected to the storage element 14, for example, via the switch 46 and the rectifier 42. The opening and closing of the switch 46 is controlled by the control device 16, for example.

[0063] In the normal operation mode, the control device 16 stops the emergency generator 40 and opens the switch 46. When the control device 16 switches from the normal operation mode to the corrosion prevention operation mode in response to the detection of a power outage in the power grid 4, the control device 16 starts the operation of the emergency generator 40 and closes the switch 46, thereby charging the storage element 14 based on the power generated by the emergency generator 40 during the power outage in the power grid 4. For example, the control device 16 may detect the voltage of the storage element 14 in the corrosion prevention operation mode, and charge the storage element 14 based on the power generated by the emergency generator 40 only when the voltage of the storage element 14 drops.

[0064] Thus, in this example, the electrolytic cell power supply device 10a further includes an emergency generator 40. This allows the DC power stored in the storage element 14 to continue operation in the corrosion prevention operation mode for a longer period of time, and thus enables deterioration of the electrolytic cell 2 due to the occurrence of reverse current to be suppressed for a longer period of time.

[0065] After the emergency generator 40 is started, it may take, for example, about 40 seconds until a stable output can be obtained. In the electrolytic cell power supply device 10a, the capacity of the storage element 14 is set so that the anticorrosion operation mode can be executed with the DC power stored in the storage element 14 for the startup time of the emergency generator 40. This makes it possible to prevent the storage element 14 from requiring excessive capacity. By reducing the capacity required for the storage element 14, it is possible to prevent the storage element 14 from becoming larger and its costs from increasing. It is possible to continue the anticorrosion operation mode for a long period of time while reducing the capacity of the storage element 14.

[0066] In this example, the electrolytic cell power supply device 10a further includes a rectifier 42, and the emergency generator 40 supplies the generated AC power to the rectifier 42, thereby charging the storage element 14 via the rectifier 42. In this way, when the power generated by the emergency generator 40 is AC power, the storage element 14 is charged via the rectifier 42 for initial charging. This reduces the need to add a separate rectifier or the like even when an AC emergency generator 40 is used, and makes it possible to reduce the number of parts and additional costs.

[0067] The power generated by the emergency generator 40 is not limited to AC power, but may be DC power. The emergency generator 40 may be a DC generator or a storage battery. In this case, the rectifier 42 may be omitted. The electrolytic cell power supply device 10a does not necessarily have to include the rectifier 42.

[0068] (Fifth embodiment) FIG. 6 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a fifth embodiment. As shown in FIG. 6, the electrolytic cell power supply device 10b further includes a first current sensor 51 and a second current sensor 52.

[0069] The first current sensor 51 is a sensor for detecting the DC current supplied from the second converter 12 to the electrolytic cell 2 in normal operation mode. The electrolytic cell power supply device 10b has, for example, a plurality of first current sensors 51 corresponding to each of the plurality of conversion circuits 20. The plurality of first current sensors 51 detect the DC current supplied from each of the plurality of conversion circuits 20 to the electrolytic cell 2 in normal operation mode. The plurality of first current sensors 51 input the detection results of the DC current to the control device 16.

[0070] In the normal operation mode, the control device 16 controls the operation of the second converter 12 based on the detection result of the first current sensor 51. In the normal operation mode, for example, the control device 16 controls the operation of each of the multiple conversion circuits 20 based on the detection result of each of the multiple first current sensors 51. For example, the control device 16 controls the operation of each of the multiple conversion circuits 20 based on the detection result of each of the multiple first current sensors 51 so that a DC current corresponding to a current command value is output from each of the multiple conversion circuits 20.

[0071] The second current sensor 52 is a sensor for detecting the DC current supplied from the second converter 12 to the electrolytic cell 2 in the corrosion prevention operation mode. The second current sensor 52 is provided, for example, between the second converter 12 and the electrolytic cell 2. In other words, the second current sensor 52 is provided between the multiple conversion circuits 20 and the electrolytic cell 2. The second current sensor 52 detects, for example, the DC current after joining of the multiple conversion circuits 20 connected in parallel. The second current sensor 52 inputs the detection result of the DC current to the control device 16.

[0072] In the anticorrosion operation mode, the control device 16 controls the operation of the second converter 12 based on the detection result of the second current sensor 52. In the anticorrosion operation mode, for example, the control device 16 controls the operation of each of the multiple conversion circuits 20 based on the detection result of the second current sensor 52. For example, the control device 16 controls the operation of each of the multiple conversion circuits 20 based on the detection result of the second current sensor 52 so that a DC current corresponding to a current command value is output from each of the multiple conversion circuits 20.

[0073] Thus, in this example, in the normal operation mode, the control device 16 controls the operation of the second converter 12 based on the detection result of the first current sensor 51, and in the corrosion prevention operation mode, the control device 16 controls the operation of the second converter 12 based on the detection result of the second current sensor 52.

[0074] As mentioned above, the DC current supplied from second converter 12 to electrolytic cell 2 in the anticorrosion operation mode is a small current, approximately 1% of the maximum value of the DC current supplied from second converter 12 to electrolytic cell 2 in the normal operation mode. In this case, the same current sensor as that used in the normal operation mode may not be able to properly detect the magnitude of the DC current supplied from second converter 12 to electrolytic cell 2 in the anticorrosion operation mode.

[0075] For this reason, the electrolytic cell power supply device 10b is equipped with two types of current sensors: a first current sensor 51 and a second current sensor 52. The second current sensor 52 is, for example, a current sensor that can detect a smaller DC current than the first current sensor 51. This allows for more appropriate detection of the magnitude of the DC current supplied from the second converter 12 to the electrolytic cell 2 in the anticorrosion operation mode. The detection result of the second current sensor 52 allows for more appropriate control of the operation of the second converter 12 in the anticorrosion operation mode.

[0076] For example, it is possible to prevent a shortage of DC current supplied from the second converter 12 to the electrolytic cell 2 and more appropriately prevent deterioration of the electrolytic cell 2. Alternatively, it is possible to prevent an excessive supply of DC current from hastening the consumption of DC power stored in the storage element 14, which would make it impossible to continue the corrosion prevention operation mode.

[0077] In this example, a plurality of first current sensors 51 are provided corresponding to the plurality of conversion circuits 20, respectively. The first current sensor 51 is not limited to this, and similar to the second current sensor 52, a single first current sensor 51 may be provided between the second converter 12 and the electrolytic cell 2.

[0078] (Sixth embodiment) FIG. 7 is a block diagram schematically illustrating a power supply device for an electrolytic cell according to a sixth embodiment. As shown in FIG. 7, the electrolytic cell power supply device 10 c further includes a plurality of current sensors 60 .

[0079] The multiple current sensors 60 are provided corresponding to the multiple conversion circuits 20, respectively. The multiple current sensors 60 detect the DC current supplied to the electrolytic cell 2 from the multiple conversion circuits 20, respectively. The multiple current sensors 60 input the detection results of the DC current to the control device 16.

[0080] The control device 16 controls the operation of the second converter 12 based on the detection results of the multiple current sensors 60. More specifically, the control device 16 controls the operation of each of the multiple conversion circuits 20 based on the detection results of each of the multiple current sensors 60. For example, the control device 16 controls the operation of each of the multiple conversion circuits 20 based on the detection results of each of the multiple current sensors 60 so that a DC current corresponding to a current command value is output from each of the multiple conversion circuits 20.

[0081] In other words, the configuration of the electrolytic cell power supply device 10c is the same as the configuration of the electrolytic cell power supply device 10b of the above embodiment, except that the second current sensor 52 is omitted and only multiple first current sensors 51 are provided. In this example, the control device 16 controls the operation of the second converter 12 based on the detection results of the multiple current sensors 60 in both the normal operation mode and the corrosion prevention operation mode.

[0082] In the electrolytic cell power supply device 10c, the control device 16 operates each of the multiple conversion circuits 20 in the normal operation mode, and operates only some of the multiple conversion circuits 20 in the anticorrosion operation mode. For example, the control device 16 operates each of the multiple conversion circuits 20 connected in parallel in the normal operation mode, and operates only one of the multiple conversion circuits 20 in the anticorrosion operation mode.

[0083] In this way, in the electrolytic cell power supply device 10c, the control device 16 operates only some of the multiple conversion circuits 20 in the anticorrosion operation mode. This allows current to be concentrated in the part of the conversion circuits 20 that are operated in the anticorrosion operation mode. In this way, by concentrating current in only some of the conversion circuits 20 in the anticorrosion operation mode, the value of the current detected by the current sensor 60 can be increased, and it is possible to accurately detect minute currents in the anticorrosion operation mode using the same current sensor 60 as in the normal operation mode. For example, this eliminates the need to separately provide a second current sensor 52 with high detection accuracy. This prevents an increase in the number of parts and allows operation in the anticorrosion operation mode to be achieved with a simpler configuration.

[0084] 8(a) and 8(b) are timing charts that schematically show an example of the operation of the power supply device for an electrolytic cell according to the sixth embodiment. Fig. 8(a) shows an example of the operation of the control device 16 in the normal operation mode, and Fig. 8(b) shows an example of the operation of the control device 16 in the corrosion prevention operation mode.

[0085] 8(a) and 8(b) schematically show an example of the switching timing of the switching elements 21 provided in each of the multiple conversion circuits 20. In Fig. 8(a) and 8(b), the on / off states of the switching elements 21 in each conversion circuit 20 are represented by High / Low signals. That is, the on state of the switching elements 21 is represented by High signals, and the off state of the switching elements 21 is represented by Low signals.

[0086] 8(a) and 8(b), the control device 16 controls the magnitude of the DC power output from each conversion circuit 20, for example, by periodically switching on and off the switching element 21 of each conversion circuit 20 and appropriately changing the on time and off time of the switching element 21 of each conversion circuit 20. The control device 16 controls the magnitude of the DC power output from each conversion circuit 20, for example, by performing PWM control.

[0087] 8(a), in the normal operation mode, the control device 16 performs control to shift the switching timing of each of the switching elements 21 of the multiple conversion circuits 20. The control device 16 shifts the ON timing of the PWM control of each of the switching elements 21 of the multiple conversion circuits 20, for example, according to the number of the multiple conversion circuits 20 connected in parallel.

[0088] As shown in Fig. 8(b), in the anticorrosion operation mode, the control device 16 performs control to make the switching frequencies of the switching elements 21 of some of the multiple conversion circuits 20 higher than the switching frequencies of the switching elements 21 of each of the multiple conversion circuits 20 in the normal operation mode. Fig. 8(b) shows an example in which only one of the multiple conversion circuits 20 is operated and the switching frequency of the switching element 21 of that one conversion circuit 20 is set to twice the switching frequency in the normal operation mode. Note that the switching frequency in the anticorrosion operation mode is not limited to twice the switching frequency, and may be any frequency higher than the switching frequency in the normal operation mode.

[0089] Thus, in this example, in the normal operation mode, the control device 16 performs control to stagger the switching timing of each of the switching elements 21 of the multiple conversion circuits 20. This makes it possible to reduce ripples superimposed on the output current in the normal operation mode.

[0090] In this example, the control device 16 controls the switching frequencies of the switching elements 21 of some of the multiple conversion circuits 20 in the anticorrosion operation mode to be higher than the switching frequencies of the switching elements 21 of each of the multiple conversion circuits 20 in the normal operation mode. This makes it possible to reduce the ripple superimposed on the output current even in the anticorrosion operation mode. Even when the number of operating conversion circuits 20 is reduced, it is possible to prevent the ripple superimposed on the output current from increasing excessively. For example, a more stable DC current can be supplied to the electrolytic cell 2.

[0091] The present embodiment includes the following aspects. (Appendix 1) A power supply device for an electrolytic cell that causes an electrolytic cell to perform electrolysis by supplying DC power between an anode and a cathode of the electrolytic cell, a first converter that converts AC power supplied from the power grid into DC power; a storage element that stores the DC power output from the first converter; a second converter that converts the DC power stored in the storage element into another DC power suitable for the electrolytic cell, and supplies the converted DC power between the anode and the cathode of the electrolytic cell; a control device for controlling the operation of the first converter and the second converter; Equipped with The control device a normal operation mode in which operations of the first converter and the second converter are controlled so that DC power for electrolysis is supplied to the electrolytic cell based on AC power supplied from the power grid when the power grid is normal; a corrosion prevention operation mode in which, in the event of a power outage in the power grid, operation of the second converter is controlled to supply to the electrolytic cell, based on the DC power stored in the storage element, DC power that is smaller than the DC power supplied to the electrolytic cell in the normal operation mode, thereby suppressing the generation of a reverse current, which is a current component that flows in the opposite direction to normal electrolysis in the electrolytic cell; A power supply device for an electrolytic cell having the same.

[0092] (Appendix 2) 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device stops operation of the first converter in the corrosion prevention operation mode.

[0093] (Appendix 3) 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device controls the operation of the first converter in the corrosion prevention operation mode so as to supply only reactive power to the power grid based on the DC power stored in the storage element.

[0094] (Appendix 4) 4. The power supply device for an electrolytic cell according to claim 1, wherein the control device gradually changes the magnitude of the DC power supplied to the electrolytic cell when switching from the normal operation mode to the anticorrosion operation mode and when switching from the anticorrosion operation mode to the normal operation mode.

[0095] (Appendix 5) 5. The power supply device for an electrolytic cell according to any one of claims 1 to 4, further comprising an emergency generator that charges the storage element in the event of a power outage in the power grid.

[0096] (Appendix 6) further comprising a rectifier for initially charging the storage element based on AC power supplied from the power grid; 6. The power supply device for an electrolytic cell according to claim 5, wherein the emergency generator generates AC power and supplies the generated AC power to the rectifier, thereby charging the storage element via the rectifier.

[0097] (Appendix 7) a first current sensor for detecting a direct current supplied from the second converter to the electrolytic cell in the normal operation mode; a second current sensor for detecting a direct current supplied from the second converter to the electrolytic cell in the corrosion prevention operation mode; Furthermore, 7. The power supply device for an electrolytic cell according to any one of appendixes 1 to 6, wherein the control device controls the operation of the second converter based on the detection result of the first current sensor in the normal operation mode, and controls the operation of the second converter based on the detection result of the second current sensor in the corrosion prevention operation mode.

[0098] (Appendix 8) the second converter has a plurality of conversion circuits connected in parallel; 8. The power supply device for an electrolytic cell according to claim 1, wherein the control device operates each of the plurality of conversion circuits in the normal operation mode, and operates only some of the plurality of conversion circuits in the corrosion prevention operation mode.

[0099] (Appendix 9) each of the plurality of conversion circuits has a switching element and performs conversion of DC power by switching the switching element; 9. The power supply device for an electrolytic cell according to claim 8, wherein the control device performs control to stagger the switching timings of the switching elements of each of the plurality of conversion circuits in the normal operation mode, and performs control to make the switching frequency of the switching elements of some of the plurality of conversion circuits higher than the switching frequency of the switching elements of each of the plurality of conversion circuits in the normal operation mode in the corrosion prevention operation mode.

[0100] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0101] DESCRIPTION OF SYMBOLS 2...Electrolytic cell, 2a...Anode, 2a...Cathode, 4...Power system, 6...Transformer, 10, 10a to 10c...Power supply device for electrolytic cell, 11...First converter, 12...Second converter, 14...Storage element, 16...Control device, 20...Conversion circuit, 20a, 20b...Input terminal, 20c, 20d...Output terminal, 21, 22...Switching element, 23, 24...Rectifier element, 25...Capacitor, 26...Reactor, 30...Switching element, 32...Rectifier element, 40...Emergency generator, 42...Rectifier, 44, 46...Switch, 48...Transformer, 51...First current sensor, 52...Second current sensor, 60...Current sensor

Claims

1. A power supply device for an electrolytic cell that causes an electrolytic cell to perform electrolysis by supplying DC power between an anode and a cathode of the electrolytic cell, a first converter that converts AC power supplied from the power grid into DC power; a second converter that converts the input DC power into another DC power; a storage element between the first converter and the second converter, the storage element being connected in parallel with the first converter and the second converter; a control device for controlling the operation of the first converter and the second converter; Equipped with The control device a normal operation mode in which operations of the first converter and the second converter are controlled so that DC power for electrolysis is supplied to the electrolytic cell based on AC power supplied from the power grid when the power grid is operating normally; a corrosion prevention operation mode in which, in the event of a power outage in the power grid, a DC power that is smaller than the DC power supplied to the electrolytic cell in the normal operation mode is supplied to the electrolytic cell based on the DC power stored in the storage element, thereby controlling the operation of the second converter so as to suppress the generation of a reverse current, which is a current component that flows in the opposite direction to normal electrolysis in the electrolytic cell; and the second converter has a plurality of conversion circuits connected in parallel; The control device operates each of the plurality of conversion circuits in the normal operation mode, and operates only some of the plurality of conversion circuits in the anticorrosion operation mode.

2. 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device stops operation of the first converter in the anticorrosion operation mode.

3. 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device controls the operation of the first converter in the corrosion prevention operation mode so as to supply only reactive power to the power grid based on the DC power stored in the storage element.

4. 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device gradually changes the magnitude of the DC power supplied to the electrolytic cell when switching from the normal operation mode to the anticorrosion operation mode and when switching from the anticorrosion operation mode to the normal operation mode.

5. 2. A power supply device for an electrolytic cell according to claim 1, further comprising an emergency generator for charging said storage element in the event of a power outage in said power grid.

6. further comprising a rectifier for initially charging the storage element based on AC power supplied from the power grid; 6. A power supply device for an electrolytic cell according to claim 5, wherein the emergency generator generates AC power and supplies the generated AC power to the rectifier, thereby charging the storage element via the rectifier.

7. A first current sensor provided between the second converter and the electrolytic cell for detecting a direct current supplied from the second converter to the electrolytic cell in the normal operation mode; a second current sensor provided between the second converter and the electrolytic bath separately from the first current sensor, for detecting a direct current supplied from the second converter to the electrolytic bath in the corrosion prevention operation mode; Furthermore, 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device controls the operation of the second converter based on the detection result of the first current sensor in the normal operation mode, and controls the operation of the second converter based on the detection result of the second current sensor in the corrosion prevention operation mode.

8. each of the plurality of conversion circuits has a switching element and performs conversion of DC power by switching the switching element; 2. The power supply device for an electrolytic cell according to claim 1, wherein the control device performs control to stagger the switching timings of the switching elements of each of the plurality of conversion circuits in the normal operation mode, and performs control to make the switching frequencies of the switching elements of some of the plurality of conversion circuits higher than the switching frequencies of the switching elements of each of the plurality of conversion circuits in the normal operation mode in the corrosion prevention operation mode.

9. A first converter that converts AC power supplied from a power grid into first DC power; a second converter having a plurality of conversion circuits connected in parallel with each other; a storage element between the first converter and the second converter, the storage element being connected in parallel with the first converter and the second converter; a control device for controlling the operation of the first converter and the second converter; Equipped with The control device When the power system is normal, the plurality of conversion circuits included in the second converter are controlled to convert the first DC power into second DC power supplied to an electrolytic cell; when a power outage occurs in the power grid, controlling some of the plurality of conversion circuits included in the second converter to convert the discharge from the storage element into third DC power smaller than the second DC power supplied to the electrolytic cell; Power supply device for electrolytic cell.

Images