JP7168541B2 - water electrolysis system - Google Patents

Description

The present invention relates to water electrolysis systems.

A water electrolysis system has been disclosed in which a solar cell and a water electrolysis cell are connected and surplus power generated by the solar cell is used for water electrolysis to achieve effective use of power.

For example, in a water electrolysis system in which a water electrolysis device having a cell group consisting of a plurality of water electrolysis cells and a solar cell as a power source of the cell group are connected, the water electrolysis cell is arranged so as to utilize the maximum output of the solar cell. A technique for selecting the number of uses is disclosed (Patent Document 1).

Further, for example, a water electrolysis device having a plurality of cell stacks each composed of a plurality of water electrolysis cells, the cell stacks being electrically connected in series or parallel to each other, and a power supply for supplying power to the water electrolysis device a voltage control unit that variably controls the voltage of the power supplied to the water electrolysis device, and the voltage and current acting on the cell stack according to the power supplied to the water electrolysis device are within a predetermined range. A configuration including a stack number control unit that selects the number of cell stacks to be used in the water electrolysis apparatus so that the number of cell stacks to be used is disclosed (Patent Document 2).

On the other hand, as a power supply system including a plurality of batteries, a configuration capable of outputting a desired output voltage as needed is disclosed. That is, battery circuit modules are connected in series each including a battery, a first switching element connected in parallel to the battery, and a second switching element connected in series to the battery between the battery and the first switching element. A power supply system is disclosed that includes a group of battery circuit modules configured as described above, and outputs gate signals for turning on and off a first switch element and a second switch element to the battery circuit modules at regular time intervals (Patent Document 3: ).

Japanese Patent Application Laid-Open No. 2001-335982 JP 2005-126792 A JP 2018-74709 A

By the way, in the configuration in which the number of series of water electrolysis units is selected so as to use the maximum output of the solar cell, the voltage applied to the water electrolysis unit becomes discrete if the number of series is simply selected. Therefore, it is not always possible to apply a voltage that maximizes the output of the solar cell, and there is a problem that the output of the solar cell cannot be effectively used.

In addition, in the case of a configuration in which the number of series connections is selected, the separated water electrolysis unit is in a state of not performing water electrolysis. In order to follow the maximum output of the solar cell, the operation/stop is repeated, which may deteriorate the water electrolysis stack.

In addition, in a configuration in which the number of cell stacks used in the water electrolysis device is selected so that the voltage and current acting on each cell stack are within a predetermined range according to the power supplied to the water electrolysis device, the cell stacks are electrically connected to each other. A means for connecting in series or parallel to the water electrolysis device and a voltage control section for variably controlling the voltage of the power supplied to the water electrolysis device are separately provided, which increases the number of parts and increases the cost.

One aspect of the present invention comprises a water electrolysis cell, a terminal for supplying power to the water electrolysis cell, a switch element connected to the terminal and connected in parallel to the water electrolysis cell, and A capacitor connected in parallel is connected in series with the water electrolysis cell between the water electrolysis cell and the switch element, and is connected in a direction to conduct electricity when electric power is supplied from the terminal to the water electrolysis cell. a water electrolysis cell module group in which a plurality of water electrolysis cell modules are connected in series via the terminals; and a control circuit that outputs to each of the water electrolysis cell modules of the group at regular time intervals.

Here, the control circuit is provided corresponding to each of the water electrolysis cell modules, and is a delay circuit that delays and transmits the gate signal between adjacent water electrolysis cell modules in the water electrolysis cell module group. wherein the period of the gate signal is the sum of the delay times in the delay circuits of the water electrolysis cell modules, and the water electrolysis cells are connected in series by turning off the switch elements. Preferably, the module is supplied with input power.

Moreover, it is preferable that the input terminal of the water electrolysis cell module group is connected to a solar cell.

Further, a solar cell maximum output control target value setting means for obtaining a target current or a target voltage at which the output of the solar cell is maximized is provided, and the control circuit controls the current flowing through the input terminal to follow the target current. Alternatively, it is preferable to control the on/off drive of the switch element so that the voltage applied to the input terminal follows the target voltage.

Further, a water electrolysis cell failure detection means for detecting a failure state of the water electrolysis cell is provided, and the switch element of the water electrolysis cell module including the water electrolysis cell whose failure is detected by the water electrolysis cell failure detection means is detected. It is preferred to keep it on.

ADVANTAGE OF THE INVENTION According to this invention, a power generation means can be utilized efficiently in the water electrolysis system using power generation means, such as a solar cell.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the water electrolysis system in embodiment of this invention. It is a figure which shows another example of the water electrolysis cell module in embodiment of this invention. FIG. 3 is a diagram showing an example of operating characteristics of a solar cell; FIG. 3 is a diagram showing an example of operating characteristics of a solar cell; FIG. 4 is a diagram showing an example of operating characteristics of a water electrolysis cell; FIG. 4 is a diagram showing an example of operating characteristics of a water electrolysis cell; It is a figure explaining control of the water electrolysis cell module in embodiment of this invention. It is a figure which shows the effect|action of the water electrolysis cell module in embodiment of this invention. 4 is a time chart illustrating control of the water electrolysis system according to the embodiment of the invention; 4 is a flow chart of forced disconnection control in the embodiment of the present invention; It is a figure which shows another example of the water electrolysis cell module in embodiment of this invention.

A water electrolysis system 100 according to the present embodiment includes a water electrolysis cell module 102 and a controller 104, as shown in FIG. The water electrolysis system 100 includes a plurality of water electrolysis cell modules 102 (102a, 102b, . . . 102n). A plurality of water electrolysis cell modules 102 can be connected in series with each other under the control of the controller 104 . A plurality of water electrolysis cell modules 102 included in the water electrolysis system 100 can receive power from a power source 106 connected to terminals T1 and T2 and use the power to electrolyze water.

Hydrogen generation technology by water electrolysis is used as a large-capacity energy storage technology for renewable energy with large output fluctuations such as photovoltaic power generation. Hydrogen is suitable for long-term storage and can be converted into electricity by power generation by fuel cells, gas turbines, etc. Therefore, it can be used as an energy buffer that absorbs long-term fluctuations in power generation, such as seasonal changes. is.

The operating point (current, voltage) at which the maximum power can be extracted from the solar cell varies depending on the illuminance with which the solar cell is illuminated and the temperature of the solar cell. Therefore, maximum power point tracking control (MPPT: Maximum Power Point Tracking) is performed to make the output of the solar cell follow the maximum power. The water electrolysis system 100 can be used in combination with MPPT control for solar cells to appropriately utilize generated power.

The water electrolysis cell module 102 includes water electrolysis cells 10 , choke coils 12 , capacitors 14 , switch elements 16 , diodes 18 , delay circuits 20 , AND elements 22 , OR elements 24 and NOT elements 26 . In this embodiment, each water electrolysis cell module 102 has the same configuration.

The water electrolysis cell 10 is a cell for electrolyzing water. That is, the water electrolysis cell 10 electrolyzes water by supplying water into a container having an anode and a cathode and applying a voltage between the anode and the cathode, generating oxygen from the anode side, and generating oxygen from the cathode side. generate hydrogen from The water electrolysis cell 10 may be a single cell, or may be configured by connecting a plurality of cells in series or in parallel.

The choke coil 12 and the capacitor 14 constitute a smoothing circuit (low-pass filter circuit) for smoothing the power supplied to the water electrolysis cell 10 . The water electrolysis cell 10 is likely to deteriorate due to frequent switching between a state in which power is supplied and a state in which it is not supplied. Therefore, deterioration of the water electrolysis cell 10 can be suppressed by forming an RLC filter with the water electrolysis cell 10, the choke coil 12 and the capacitor 14 to level the current flowing through the water electrolysis cell 10. FIG.

Note that the choke coil 12 and the capacitor 14 are not essential components and may be omitted. For example, the inductance of the choke coil 12 may be covered by the inductance of the water electrolysis cell itself or wiring. In addition, in the water electrolysis cell module 102, the choke coil 12 and the water electrolysis cell 10 may be interchanged in position (connection position).

The switch element 16 includes a switch element for short-circuiting the output terminals of the water electrolysis cell 10 . In the present embodiment, the switch element 16 has a configuration in which a freewheeling diode is connected in parallel with a field effect transistor that is a switch element. The switch element 16 is switching-controlled by a gate signal from the control section 104 . In this embodiment, the switch element 16 is a field effect transistor, but other switch elements may be used. Alternatively, a built-in diode may be used instead of the freewheeling diode.

A diode 18 is provided to define the direction of current supplied from the power supply 106 to the water electrolysis cell 10 . Diode 18 is connected in series with water electrolysis cell 10 between water electrolysis cell 10 and switch element 16 . However, the diode 18 may be arranged on the side opposite to the output terminal with respect to the switch element 16, as shown in FIG. In other words, it is sufficient that the connection is made in the direction in which it is energized when voltage is applied to the water electrolysis cell 10 from the power source 106 . Alternatively, as shown in FIG. 11, an FET 18a may be used instead of the diode 18 for synchronous rectification. Thereby, loss in the switch element 16 can be reduced.

The delay circuit 20 is a circuit that delays the gate signal input from the control unit 104 to the water electrolysis cell module 102 by a predetermined time. In the water electrolysis system 100, each water electrolysis cell module 102 (102a, 102b, . . . 102n) is provided with a delay circuit 20, which are connected in series. Therefore, the gate signal input from the control unit 104 is sequentially input to each water electrolysis cell module 102 (102a, 102b, . . . 102n) while being delayed by a predetermined time.

The AND element 22 constitutes disconnection means for forcibly disconnecting the water electrolysis cell module 102 a from the series connection state in response to a forced disconnection signal from the control unit 104 . Moreover, the OR element 24 constitutes connection means for forcibly connecting the water electrolysis cell modules 102 a in a series connection state in response to a forced connection signal from the control section 104 .

Although the delay circuit 20 is arranged before the AND element 22 and the OR element 24 in this embodiment, it may be arranged after the AND element 22 and the OR element 24 . That is, it is sufficient that the gate signal is delayed by a predetermined time and transmitted sequentially to the delay circuit 20 of each water electrolysis cell module 102 .

The power supply 106 is power supply means for supplying power to the water electrolysis cell module 102 . In this embodiment mode, the power source 106 is a solar cell including a photoelectric conversion element that generates power by light irradiation. However, the power source 106 is not limited to this, and may be provided with other power generation means such as thermal power generation, hydraulic power generation, geothermal power generation, wind power generation, and fuel cells.

[System configuration]
FIG. 3 shows an example of solar radiation intensity characteristics of a solar cell. Moreover, FIG. 4 shows an example of temperature characteristics of a solar cell. As described above, the operating point (current, voltage) at which the maximum power can be extracted from the solar cell varies depending on the illuminance illuminating the solar cell and the temperature of the solar cell.

On the other hand, FIG. 5 shows an example of voltage-current characteristics of the water electrolysis cell 10. As shown in FIG. The voltage of the water electrolysis cell 10 is as low as about 1.5V to 2.0V for a single cell. Therefore, it is generally used as a water electrolysis cell 10 in which multiple cells are connected in series. For example, as shown in FIG. 6, a water electrolysis cell 10 in which two cells each using an Ir-ND catalyst and having an area of 15 cm ² are connected in series has an output voltage of about 3.2V to 4V.

A water electrolysis system 100 including a plurality of water electrolysis cell modules 102 including such water electrolysis cells 10 and a solar cell having a maximum output voltage of 35.2 V at a maximum output of 280 W is connected as the power source 106 will be examined. Specifically, the characteristics shown in Table 1.

First, the required number of water electrolysis cell modules 102 to be incorporated in the water electrolysis system 100 is determined. The number of water electrolysis cell modules 102 to be connected must correspond to the voltage of the solar battery that is the power supply 106 . Therefore, in order to correspond to the output voltage of 35.2 V, the maximum output voltage of the solar cell with the minimum voltage of 3.2 [V] of the water electrolysis cell module 102, (maximum output voltage of the solar cell)/(water electrolysis cell module 102) minimum voltage)=35.2/3.2≈11 water electrolysis cell modules 102 are required at a minimum.

Next, the water electrolysis cell module 102 needs a margin in order to maintain the operation of the water electrolysis system 100 even if the water electrolysis cell module 102 fails. For example, in order to maintain the system even if two water electrolysis cell modules 102 fail, a margin for two water electrolysis cell modules 102 is required, so 13 water electrolysis cell modules 102 are required. becomes.

Furthermore, in order to set the control duty (the ratio of the water electrolysis cell modules 102 connected in series simultaneously in the water electrolysis system 100) to 0.9 or less with a control margin, 13/0.9≈15 water electrolysis cells A module 102 is required.

Next, the number of parallel-connected solar cells that are the power source 106 is obtained. When two of the 15 water electrolysis cell modules 102 are passed through and 13 water electrolysis cell modules 102 are used, the power required for electrolysis of water is 129W×13=1677W. In order to supply this necessary power from the solar cell module of FIG. 6, 1677 W/280 W=5.99, and six solar cell modules are required.

[Normal control]
Control of the water electrolysis system 100 will be described below with reference to FIG. During normal control, a high (H) level forced disconnection signal is input from the control unit 104 to the AND elements 22 of the water electrolysis cell modules 102 (102a, 102b, . . . 102n). Also, a low (L) level forced connection signal is input from the control unit 104 to the OR element 24 of each water electrolysis cell module 102 (102a, 102b, . . . 102n). Therefore, the output signal from the delay circuit 20 is input to the gate terminal of the switch element 16 via the NOT element 26 as an inverted signal.

FIG. 7 shows a time chart regarding the operation of the water electrolysis cell module 102a. 7, the pulse waveform of the gate signal D1 that drives the water electrolysis cell module 102a, the rectangular wave D2 that indicates the switching state of the switch element 16, and the waveform D3 of the voltage V _mod applied to the water electrolysis cell module 102a. is shown.

In the initial state of the water electrolysis cell module 102a, that is, in a state in which no gate signal is output, the switch element 16 is on. Then, when a gate signal is input from the control unit 104 to the water electrolysis cell module 102a, the water electrolysis cell module 102a is switching-controlled by PWM control. In this switching control, the switch element 16 is switched between an on state and an off state.

As shown in FIG. 7, when the gate signal D1 is output from the controller 104, the switch element 16 of the water electrolysis cell module 102a is driven according to the gate signal D1. The switch element 16 is switched from the on state to the off state by the fall of the signal from the NOT element 26 corresponding to the rise of the gate signal D1.

In the water electrolysis cell module 102a, when the gate signal D1 is off (that is, the switch element 16 is on), both terminals of the water electrolysis cell module 102a are short-circuited and no voltage is applied from the power supply 106. In this state, as shown in FIG. 8A, the water electrolysis cell 10 (capacitor 14) of the water electrolysis cell module 102a is bypassed.

When the gate signal D1 is on (that is, when the switch element 16 is off), both terminals of the water electrolysis cell module 102a are open. Therefore, voltage is applied from the power source 106 to the water electrolysis cell module 102a. In this state, as shown in FIG. 8(b), a voltage V _mod is applied via the capacitor 14 in the water electrolysis cell module 102a.

Next, control of the water electrolysis system 100 by the controller 104 will be described. The control unit 104 controls the entire water electrolysis cell module 102 . That is, by controlling the plurality of water electrolysis cell modules 102a, 102b, .

The control unit 104 includes a gate circuit that outputs a square-wave gate signal to each water electrolysis cell module 102 . The gate signal is transmitted to the water electrolysis cell module 102 in the succeeding stage, such as the delay circuit 20 included in the water electrolysis cell module 102a, the delay circuit 20 included in the water electrolysis cell module 102b, and so on. That is, the gate signal is delayed by a predetermined delay time in order from the most upstream side of the water electrolysis cell modules 102 connected in series in the water electrolysis system 100 and transmitted downstream.

During normal control, a high (H) level forced disconnection signal is input to AND element 22 from control section 104, and a low (L) level forced connection signal is input to OR element 24 from control section 104. Therefore, a signal obtained by inverting the gate signal output from the delay circuit 20 of each water electrolysis cell module 102 is input to the gate terminal of the switch element 16 . Therefore, when the gate signal is at high (H) level, switch element 16 is turned off, and when the gate signal is at low (L) level, switch element 16 is turned on.

That is, when the gate signal is at high (H) level, the water electrolysis cell module 102 is connected in series with other water electrolysis cell modules 102, and when the gate signal is at low (L) level, the water electrolysis cell module 102 is connected in series. 102 is in a through state separated from other water electrolysis cell modules 102 .

FIG. 9 shows a control sequence for sequentially connecting a predetermined number of water electrolysis cell modules 102a, 102b, . . . 102n in series to output power. As shown in FIG. 9, the water electrolysis cell modules 102a, 102b, . In FIG. 9, during period E1, the switch elements 16 of the water electrolysis cell modules 102a, 102b, . It shows the receiving state (connection state). In period E2, the switch elements 16 of the water electrolysis cell modules 102a, 102b, . (through state). In this manner, the water electrolysis cell modules 102a, 102b, . . . 102n are sequentially driven with a constant delay time.

The setting of the gate signal and the delay time of the gate signal will be described with reference to FIG. The period F of the gate signal is set by summing the delay times of the water electrolysis cell modules 102a, 102b, . . . 102n. Therefore, the longer the delay time, the lower the frequency of the gate signal. Conversely, the shorter the delay time, the higher the frequency of the gate signal. Also, the delay time for delaying the gate signal is appropriately set according to the specifications required for the water electrolysis system 100 .

The on-time ratio G1 (duty ratio D) in the period F of the gate signal, that is, the ratio of the time during which the gate signal is at the high (H) level in the period F is the terminal voltage of the water electrolysis system 100/the water electrolysis cell module. 102a, 102b, . That is, the on-time ratio G1=(terminal voltage of water electrolysis system 100)/(terminal voltage of water electrolysis cell modules 102×number of water electrolysis cell modules 102).

The total terminal voltage of the water electrolysis cell modules 102a, 102b, . represented by a value. If the output voltage of the power supply 106 is divisible by the terminal voltage of one water electrolysis cell module 102, the moment the water electrolysis cell module 102 switches from the through state to the connected state, the other water electrolysis cell module 102 is in the connected state. to the through state, the output voltage of the entire water electrolysis cell module 102 does not fluctuate.

However, if the output voltage of the power supply 106 is a value that is not divisible by the terminal voltage of each water electrolysis cell module 102, the output voltage of the power supply 106 and the total terminal voltage of the water electrolysis cell modules 102a, 102b, . do not do. At this time, the total voltage of the entire water electrolysis system 100 fluctuates. However, the fluctuation amplitude at this time is the voltage for one water electrolysis cell module, and the fluctuation period is the gate signal period F/the number of water electrolysis cell modules 102 . By connecting a large number of water electrolysis cell modules 102 in series, the parasitic inductance of the entire water electrolysis system 100 has a large value, and this voltage fluctuation is filtered out, resulting in a stable output voltage of the water electrolysis system 100. Obtainable.

Next, a specific example will be described. 8, for example, the desired output voltage of the power supply 106 is 35.2 V, the terminal voltage of each water electrolysis cell module 102 is 3.2 V, the number of water electrolysis cell modules 102a, 102b, . Let time be 200 ns. This case corresponds to the case where the output voltage (35.2 V) of the power supply 106 is not divisible by the terminal voltage (3.5 V) of the water electrolysis cell module 102 .

Based on these numerical values, the cycle F of the gate signal is calculated from the delay time×the number of water electrolysis cell modules, so 200 ns×15=3 μs. Therefore, the gate signal is a rectangular wave with a frequency corresponding to approximately 333 kHz. In addition, since the on-time ratio G1 of the gate signal is calculated by the voltage of the water electrolysis system 100 (=the output voltage of the power supply 106)/(the terminal voltage of the water electrolysis cell module 102×the number of the water electrolysis cell modules 102), The on-time ratio G1 is 35.2 V/(3.5 V×15 pieces)≈0.67.

When the water electrolysis cell modules 102a, 102b, . This terminal voltage H1 fluctuates between 35.0V and 38.5V. That is, the terminal voltage H1 fluctuates at a period calculated by the gate signal period F/the number of water electrolysis cell modules, that is, 3 μs/15=200 ns. This fluctuation is filtered by the parasitic inductance due to the wiring of the water electrolysis cell modules 102a, 102b, .

A current flows through the capacitor 14 of each water electrolysis cell module 102 in the connected state, and as shown in FIG. 9, the capacitor current waveform J1 becomes a rectangular wave. In addition, since the water electrolysis cell 10 and the capacitor 14 form an RLC filter, the water electrolysis system 100 carries a filtered and leveled current J2. In this way, the current waveform is uniform in all the water electrolysis cell modules 102a, 102b, . . In this way, the current of the water electrolysis system 100 is leveled while controlling the output voltage. Deterioration of the system 100 can be suppressed.

As described above, when controlling the water electrolysis system 100, the gate signal output to the most upstream water electrolysis cell module 102a is output to the downstream water electrolysis cell module 102b with a certain time delay. , this gate signal is delayed by a certain time and sequentially transmitted to the water electrolysis cell modules 102 on the downstream side, so that the water electrolysis cell modules 102a, 102b, . . . applied. Then, each of the water electrolysis cell modules 102 included in the water electrolysis system 100 can electrolyze water according to the output voltage of the power supply 106 .

The voltage output from the power supply 106 may be set according to the state of the power supply 106 so that the efficiency of the power supply 106 is high. For example, if the power source 106 is a solar cell, it may be set to the maximum output voltage at the maximum power operating point according to the sunlight condition and temperature for the solar cell. Specifically, the voltage sensor 34 provided between the terminals of the water electrolysis system 100 measures the output voltage of the power supply 106, and the controller 104 sets the on-time ratio G1 according to the output voltage of the power supply 106. . As a result, the water electrolysis system 100 can be operated by accurately following the maximum power operating point of the solar cell under MPPT control.

According to the water electrolysis system 100, the step-down circuit is not required, the circuit configuration can be simplified, and the size and cost can be reduced. Moreover, a balance circuit or the like that causes power loss is not required, and the efficiency of the water electrolysis system 100 can be improved. Furthermore, since the voltage is applied substantially equally to the plurality of water electrolysis cell modules 102a, 102b, . deterioration can be suppressed.

Further, by adjusting the on-time ratio G1, a desired voltage can be easily accommodated, and the versatility of the water electrolysis system 100 can be improved. In particular, even if the water electrolysis cell modules 102a, 102b, . By using the water electrolysis cell module 102 and resetting the period F of the gate signal, the on-time ratio G1, and the delay time, it is possible to correspond to the desired voltage. That is, even if a failure occurs in the water electrolysis cell modules 102a, 102b, .

Furthermore, by setting a long delay time for delaying the gate signal, the frequency of the gate signal becomes low, so that the switching frequency of the switch element 16 and the diode 18 also becomes low, and switching loss can be reduced. Conversely, by shortening the delay time for delaying the gate signal, the frequency of the gate signal becomes high, so the frequency of the voltage fluctuation becomes high, filtering becomes easier, and stable water electrolysis can be performed. . It also facilitates smoothing current fluctuations with the RLC filter. By adjusting the delay time for delaying the gate signal in this way, it is possible to provide the water electrolysis system 100 that meets the required specifications and performance.

In the present embodiment, each water electrolysis cell module 102 is provided with the delay circuit 20 to transmit the gate signal while delaying it. However, the present invention is not limited to this. For example, each water electrolysis cell module 102 may be configured without the delay circuit 20 . In this case, gate signals may be individually output from the control unit 104 to the AND element 22 and the OR element 24 of each water electrolysis cell module 102 . That is, the controller 104 outputs gate signals to the water electrolysis cell modules 102a, 102b, . . . 102n at regular time intervals. At this time, the water electrolysis cell modules 102a, 102b, . . . . Controls the number of water electrolysis cell modules 102 to which 102n is connected by outputting a gate signal at regular time intervals. For example, first, a gate signal is output to the water electrolysis cell module 102b to drive the water electrolysis cell module 102b, and after a certain period of time, a gate signal is output to the water electrolysis cell module 102a to drive the water electrolysis cell module 102a. Control should be performed so that

This configuration eliminates the need for the delay circuit 20, further simplifies the configuration of the water electrolysis system 100, and reduces manufacturing costs and power consumption.

[Forced disconnection control]
Next, control for forcibly disconnecting a selected one of the plurality of water electrolysis cell modules 102 (102a, 102b, . . . 102n) will be described. The control unit 104 outputs a low (L) level forced disconnection signal to the AND element 22 of the water electrolysis cell module 102 to be forcibly disconnected. The control unit 104 also outputs a low (L) level forced connection signal to the OR element 24 of the water electrolysis cell module 102 .

As a result, the AND element 22 outputs a low (L) level, and the NOT element 26 inputs a high (H) level to the gate terminal of the switch element 16 via the OR element 24 . Therefore, the switch element 16 is always on, and the water electrolysis cell module 102 is forcibly disconnected (through state) regardless of the state of the gate signal.

Such forced disconnection control can be used to cope with a failure of the water electrolysis cell module 102 in the water electrolysis system 100 . FIG. 10 shows a flow chart of control for failure of the water electrolysis cell module 102 . Hereinafter, control when any of the water electrolysis cell modules 102 fails will be described with reference to FIG. 10 .

In step S10, the states of all the water electrolysis cell modules 102 included in the water electrolysis system 100 are determined. The control unit 104 uses the voltage sensor 30 to detect the terminal voltage of the water electrolysis cells 10 included in the water electrolysis cell module 102 when voltage is applied from the power supply 106 . A failure of the water electrolysis cell 10 is detected according to the detection result of the voltage sensor 30 . For example, if the voltage measured by the voltage sensor 30 when voltage is applied from the power supply 106 is below a predetermined reference value, it is determined that the water electrolysis cell 10 is out of order.

In step S12, it is determined whether or not there is a water electrolysis cell module 102 including the water electrolysis cell 10 that has failed in the water electrolysis system 100 . Based on the determination result in step S10, if there is a water electrolysis cell module 102 including the failed water electrolysis cell 10, the control unit 104 shifts the process to step S14, otherwise ends the forced disconnection control.

In step S14, the water electrolysis cell module 102 is forcibly disconnected. The control unit 104 outputs a low (L) level forced disconnection signal to the AND element 22 of the water electrolysis cell module 102 determined to be defective in step S10. As a result, the selected water electrolysis cell module 102 is forcibly disconnected from the series connection and no longer contributes to water electrolysis in the water electrolysis system 100 .

With the above control, the water electrolysis cell module 102 including the failed water electrolysis cell 10 can be forcibly separated from the water electrolysis cell modules 102 included in the water electrolysis system 100 . As a result, it is possible to prevent the entire water electrolysis system 100 from stopping due to failure of some of the water electrolysis cell modules 102 . Therefore, the water electrolysis system 100 can be stably operated.

[Forced connection control]
It should be noted that it is also possible to forcibly connect a selected one of the plurality of water electrolysis cell modules 102 (102a, 102b, . . . 102n). The control unit 104 outputs a high (H) level forced connection signal to the OR element 24 of the water electrolysis cell module 102 to be forcibly connected. As a result, the OR element 24 outputs a high (H) level, and the NOT element 26 inputs a low (L) level to the gate terminal of the switch element 16 . Therefore, the switch element 16 is always turned off, and the water electrolysis cell module 102 is forcibly connected in series regardless of the state of the gate signal.

Such forced connection control can force water electrolysis to be performed by the water electrolysis cells 10 included in a specific water electrolysis cell module 102 in the water electrolysis system 100 . For example, when it is necessary to generate hydrogen or oxygen from the water electrolysis cell 10 included in any of the water electrolysis cell modules 102, the water electrolysis cell module 102 may be forcibly connected.

10 water electrolytic cell, 12 choke coil, 14 capacitor, 16 switch element, 18 diode, 18a FET, 20 delay circuit, 22 AND element, 24 OR element, 26 NOT element, 30 voltage sensor, 32 current sensor, 34 voltage sensor, 100 water electrolysis system, 102 (102a, 102b, ... 102n) water electrolysis cell module.

Claims (5)

a water electrolysis cell, a terminal for supplying power to the water electrolysis cell, a switch element connected to the terminal and connected in parallel to the water electrolysis cell, a capacitor connected in parallel to the water electrolysis cell, a diode connected in series with the water electrolysis cell between the water electrolysis cell and the switch element, and connected in a direction that conducts electricity when electric power is supplied to the water electrolysis cell from the terminal. a water electrolysis cell module group in which a plurality of cell modules are connected in series via the terminals;
a control circuit that outputs a gate signal for turning on and off the switch element of the water electrolysis cell module to each of the water electrolysis cell modules of the water electrolysis cell module group at regular time intervals;
A water electrolysis system comprising: The water electrolysis system according to claim 1,
The control circuit is provided corresponding to each of the water electrolysis cell modules, and includes a delay circuit that delays and transmits the gate signal between adjacent water electrolysis cell modules in the water electrolysis cell module group,
The period of the gate signal is the sum of the delay times in the delay circuits of the water electrolysis cell modules, and is input to the water electrolysis cell modules connected in series by turning off the switch elements. A water electrolysis system, characterized in that electric power is supplied. The water electrolysis system according to claim 1 or 2,
A water electrolysis system, wherein an input terminal of the water electrolysis cell module group is connected to a solar cell. The water electrolysis system according to claim 3,
Solar cell maximum output control target value setting means for determining a target current or target voltage that maximizes the output of the solar cell,
The control circuit controls on/off driving of the switch element such that the current flowing through the input terminal follows the target current or the voltage applied to the input terminal follows the target voltage. A water electrolysis system characterized by: The water electrolysis system according to any one of claims 1 to 4,
Water electrolysis cell failure detection means for detecting a failure state of the water electrolysis cell,
A water electrolysis system, wherein said switch element of said water electrolysis cell module including said water electrolysis cell whose failure has been detected by said water electrolysis cell failure detection means is maintained in an ON state.

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