JP2021063280A - Water electrolysis system - Google Patents

Abstract

To provide a water electrolysis system that can enhance the utilization efficiency of means of electric power generation for a solar cell etc.SOLUTION: A water electrolysis system 100 comprises: a group of water electrolysis cell modules, which are composed of multiple water electrolysis cell modules 102 connected in series through terminals, and each module of which includes a water electrolysis cell 10, a terminal for supplying an electric power to the water electrolysis cell 10, a switch element 16 that is connected to the terminal and connected in parallel to the water electrolysis cell 10, a capacitor 14 connected in parallel to the water electrolysis cell 10, and a diode 18 that is connected in series to the water electrolysis cell 10 between the water electrolysis cell 10 and the switch element 16 in such a direction that the diode is energized when the electric power is supplied to the water electrolysis cell 10 from an input terminal; and a control circuit 104 that outputs, on a regular basis, a gate signal for on-off switching of the switch element 16 of the water electrolysis cell module 102 to each water electrolysis cell module 102 of the group of water electrolysis cell modules.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water electrolysis system.

A water electrolysis system is disclosed in which a solar cell and a water electrolysis cell are connected and the surplus electric power generated by the solar cell is used for water electrolysis to effectively utilize the electric 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 maximum output of the solar cell can be used. A technique for selecting the number of uses is disclosed (Patent Document 1).

Further, for example, a water electrolyzer having a plurality of cell stacks composed of a plurality of water electrolyzers and having the cell stacks electrically connected in series or parallel to each other, and a power supply for supplying power to the water electrolyzer. In the water electrolysis system connected to the means, the 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 for selecting the number of cell stacks to be used in the water electrolysis apparatus 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 required is disclosed. That is, a battery circuit module including a battery, a first switch element connected in parallel to the battery, and a second switching element connected in series to the battery between the battery and the first switch element is connected in series. A power supply system is disclosed that includes a group of battery circuit modules and outputs a gate signal for on / off driving a first switch element and a second switch element to the battery circuit module at regular intervals (Patent Document 3). ).

Japanese Unexamined Patent Publication No. 2001-335982 Japanese Unexamined Patent Publication No. 2005-126792 JP-A-2018-74709

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

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

Further, in a configuration in which the number of cell stacks used in the water electrolyzer 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 electrolyzer, the cell stacks are electrically connected to each other. A means for connecting in series or in parallel with the water electrolyzer and a voltage control unit for variably controlling the voltage of the electric power supplied to the water electrolyzer are separately provided, and there is a problem that the number of parts increases and the cost increases.

One embodiment of the present invention includes 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 the water electrolysis cell. The capacitor connected in parallel is connected in series to the water electrolysis cell between the water electrolysis cell and the switch element, and is connected in a direction to energize the water electrolysis cell when power is supplied from the terminal. A group of water electrolysis cell modules in which a plurality of water electrolysis cell modules including the above-mentioned diode are connected in series via the terminals, and a gate signal for driving the switch element of the water electrolysis cell module on and off are transmitted to the water electrolysis cell module. It is a water electrolysis system characterized in that it is provided with a control circuit that outputs to each of each of the group of water electrolysis cell modules at regular time intervals.

Here, the control circuit is provided corresponding to the water electrolysis cell module, and is a delay circuit that transmits the gate signal with a delay of a certain period of time between adjacent water electrolysis cell modules in the water electrolysis cell module group. The period of the gate signal is the total value of the delay times in the delay circuits of each of the water electrolysis cell modules, and the water electrolysis cells are connected in series by turning off the switch element. It is preferred that the module be supplied with input power.

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

Further, the solar cell maximum output control target value setting means for obtaining the target current or target voltage at which the output of the solar cell is maximized is provided, and the control circuit is provided so that the current flowing through the input terminal follows 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, the switch element of the water electrolysis cell module including the water electrolysis cell for which a failure is detected by the water electrolysis cell failure detection means is provided with the water electrolysis cell failure detection means for detecting the failure state of the water electrolysis cell. It is preferable to keep it on.

According to the present invention, the power generation means can be efficiently used in a water electrolysis system using a power generation means such as a solar cell.

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. It is a figure which shows the example of the operating characteristic of a solar cell. It is a figure which shows the example of the operating characteristic of a solar cell. It is a figure which shows the example of the operation characteristic of a water electrolysis cell. It is a figure which shows the example of the operation characteristic of a water electrolysis cell. It is a figure explaining the control of the water electrolysis cell module in embodiment of this invention. It is a figure which shows the operation of the water electrolysis cell module in embodiment of this invention. It is a time chart explaining the control of the water electrolysis system in embodiment of this invention. It is a flowchart of forced disconnection control in embodiment of this invention. It is a figure which shows another example of the water electrolysis cell module in embodiment of this invention.

As shown in FIG. 1, the water electrolysis system 100 in the present embodiment includes a water electrolysis cell module 102 and a control unit 104. The water electrolysis system 100 includes a plurality of water electrolysis cell modules 102 (102a, 102b, ... 102n). The plurality of water electrolysis cell modules 102 can be connected in series to each other under the control of the control unit 104. The plurality of water electrolysis cell modules 102 included in the water electrolysis system 100 can receive electric power from the power sources 106 connected to the terminals T1 and T2 and use the electric 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 to electricity by power generation from fuel cells and gas turbines, so 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 in a solar cell changes depending on the illuminance illuminating the solar cell and the temperature of the solar cell. Therefore, maximum power point tracking (MPPT) 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 the solar cell to appropriately utilize the generated power.

The water electrolysis cell module 102 includes a water electrolysis cell 10, a choke coil 12, a capacitor 14, a switch element 16, a diode 18, a delay circuit 20, an AND element 22, an OR element 24, and a NOT element 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 applying a voltage between the anode and the cathode while supplying water into the container having the anode and the cathode, generates oxygen from the anode side, and generates oxygen from the anode side. Generates hydrogen from. The water electrolysis cell 10 may be a single cell, or a plurality of cells may be connected in series or in parallel.

The choke coil 12 and the capacitor 14 form a smoothing circuit (low-pass filter circuit) for smoothing the electric power supplied to the water electrolysis cell 10. The water electrolysis cell 10 is liable to deteriorate by frequently switching between a state in which electric power is supplied and a state in which electric power 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.

The choke coil 12 and the capacitor 14 are not indispensable configurations, and it is not necessary to provide them. For example, the inductance of the choke coil 12 may be covered by the inductance of the water electrolysis cell itself or the wiring. Further, in the water electrolysis cell module 102, the arrangement positions (connection positions) of the choke coil 12 and the water electrolysis cell 10 may be exchanged.

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

The diode 18 is provided to define the direction of the current supplied from the power source 106 to the water electrolysis cell 10. The diode 18 is connected in series with the water electrolysis cell 10 between the water electrolysis cell 10 and the switch element 16. However, as shown in FIG. 2, the diode 18 may be arranged on the opposite side of the output terminal with respect to the switch element 16. That is, it suffices that the water electrolysis cell 10 is connected in the direction of energization when a voltage is applied from the power source 106. Alternatively, as shown in FIG. 11, the FET 18a may be used instead of the diode 18 for synchronous rectification. Thereby, the 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, delay circuits 20 are provided in each of the water electrolysis cell modules 102 (102a, 102b, ... 102n), and they 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 a cutting means for forcibly disconnecting the water electrolysis cell module 102a from the series connection state in response to the forced disconnection signal from the control unit 104. Further, the OR element 24 constitutes a connection means for forcibly connecting the water electrolysis cell module 102a to the series connection state in response to the forced connection signal from the control unit 104.

In the present embodiment, the delay circuit 20 is arranged in the front stage of the AND element 22 and the OR element 24, but may be arranged in the rear stage of the AND element 22 and the OR element 24. That is, the gate signal may be delayed by a predetermined time and transmitted in order to the delay circuit 20 of each water electrolysis cell module 102.

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

[System configuration]
FIG. 3 shows an example of the solar radiation intensity characteristics of a solar cell. Further, FIG. 4 shows an example of the temperature characteristics of the solar cell. As described above, the operating point (current, voltage) at which the maximum power can be drawn out in the solar cell changes 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 the voltage-current characteristics of the water electrolysis cell 10. 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 cells are connected in multiple series. For example, as shown in FIG. 6, ^{in the water electrolysis cell 10 in which two cells having an area of 15 cm 2} using an Ir-ND catalyst are connected in series, the output voltage is about 3.2 V to 4 V.

A configuration of a water electrolysis system 100 including a plurality of water electrolysis cell modules 102 including such a water electrolysis cell 10 and connecting a solar cell having a maximum output voltage of 35.2 V at a maximum output of 280 W as a 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 obtained. It is necessary to correspond to the voltage of the solar cell which is the power source 106 depending on the number of connected water electrolysis cell modules 102. Therefore, in order to correspond to the output voltage of the maximum output voltage of the solar cell of 35.2 V at 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, even if the water electrolysis cell module 102 fails, the water electrolysis cell module 102 needs to have a margin in order to maintain the operation of the water electrolysis system 100. For example, in order to maintain the system even if up to two water electrolysis cell modules 102 fail, the water electrolysis cell module 102 needs a margin of two, so thirteen water electrolysis cell modules 102 are required. It becomes.

Further, in order to reduce the control duty (the ratio of the water electrolysis cell modules 102 connected in series in the water electrolysis system 100) to 0.9 or less in view of the control margin, 13 / 0.9 ≈ 15 water electrolysis cells Module 102 is required.

Next, the number of solar cells connected in parallel, which is the power source 106, is obtained. When 13 water electrolysis cell modules 102 are used by passing through 2 of the 15 water electrolysis cell modules 102, the electric power required for electrolysis of water is 129 W × 13 = 1677 W. In order to supply this required power from the solar cell module of FIG. 6, 1677W / 280W = 5.99, and six solar cell modules are required.

[Normal control]
Hereinafter, the control of the water electrolysis system 100 will be described with reference to FIG. 7. During normal control, a high (H) level forced disconnection signal is input from the control unit 104 to the AND element 22 of each water electrolysis cell module 102 (102a, 102b, ... 102n). Further, 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 as an inverting signal via the NOT element 26.

FIG. 7 shows a time chart relating to the operation of the water electrolysis cell module 102a. Further, in FIG. 7, the pulse waveform of the gate signal D1 for driving the water electrolysis cell module 102a, the square wave D2 indicating 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 the state where the gate signal is not output, the switch element 16 is in the ON state. Then, when the gate signal is input to the water electrolysis cell module 102a from the control unit 104, the water electrolysis cell module 102a is switched and controlled by PWM control. In this switching control, the switch element 16 is switched to the on state / off state.

As shown in FIG. 7, when the gate signal D1 is output from the control unit 104, the switch element 16 of the water electrolysis cell module 102a is driven in response to the gate signal D1. The switch element 16 switches from the on state to the off state by the falling edge of the signal from the NOT element 26 in response to the rising edge 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 and is in a through state.

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

Next, the control of the water electrolysis system 100 by the control unit 104 will be described. The control unit 104 controls the entire water electrolysis cell module 102. That is, the plurality of water electrolysis cell modules 102a, 102b, ... 102n are controlled to control the power supply from the power source 106 to each water electrolysis cell module 102.

The control unit 104 includes a gate circuit that outputs a rectangular wave gate signal to each water electrolysis cell module 102. The gate signal is sequentially transmitted to 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 to the subsequent water electrolysis cell module 102. 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 is transmitted to the downstream side.

During normal control, a high (H) level forced disconnection signal is input from the control unit 104 to the AND element 22, and a low (L) level forced connection signal is input from the control unit 104 to the OR element 24. 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, the switch element 16 is turned off when the gate signal is at the high (H) level, and the switch element 16 is turned on when the gate signal is at the low (L) level.

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

FIG. 9 shows a control sequence in which a predetermined number of the water electrolysis cell modules 102a, 102b, ... 102n are sequentially connected in series to output electric power. As shown in FIG. 9, the water electrolysis cell modules 102a, 102b, ... 102n are driven one after another from the upstream side to the downstream side with a constant delay time in response to the gate signal. In FIG. 9, during the period E1, the switch elements 16 of the water electrolysis cell modules 102a, 102b, ... 102n are turned off, and the water electrolysis cell modules 102a, 102b, ... 102n supply power from the power supply 106. Indicates the receiving state (connection state). Further, during the period E2, the switch element 16 of the water electrolysis cell modules 102a, 102b, ... 102n is turned on, and power is not supplied from the power supply 106 to the water electrolysis cell modules 102a, 102b, ... 102n. (Through state) is shown. In this way, 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. Further, 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 / water electrolysis cell module of the water electrolysis system 100. It is calculated by the voltage applied from the power supply 106 to 102a, 102b, ... 102n (terminal voltage of each water electrolysis cell module 102 x number of water electrolysis cell modules). That is, the on-time ratio G1 = (terminal voltage of the water electrolysis system 100) / (terminal voltage of the water electrolysis cell module 102 × number of water electrolysis cell modules 102).

As described above, the total terminal voltage of the water electrolysis cell modules 102a, 102b, ... 102n is obtained by multiplying the terminal voltage of each water electrolysis cell module 102 by the number of water electrolysis cell modules 102 connected in series with each other. Represented by a value. If the output voltage of the power supply 106 is a value divisible by the terminal voltage of one water electrolysis cell module 102, the other water electrolysis cell module 102 is in the connected state at the moment when the water electrolysis cell module 102 switches from the through state to the connected state. Since it switches to the through state, there is no change in the overall output voltage of the water electrolysis cell module 102.

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, ... 102n are matched. do not. 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 this fluctuation cycle is the period F of the gate signal / the number of water electrolysis cell modules 102. If a large number of water electrolysis cell modules 102 are connected in series, the parasitic inductance of the entire water electrolysis system 100 becomes a large value, and this voltage fluctuation is filtered, resulting in a stable output voltage of the water electrolysis system 100. Obtainable.

Next, a specific example will be described. In FIG. 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, ... 102n is 15, delay. Suppose the time is 200 ns. In this case, the output voltage (35.2V) of the power supply 106 is not divisible by the terminal voltage (3.5V) of the water electrolysis cell module 102.

Based on these numerical values, the period F of the gate signal is calculated by multiplying the delay time by the number of water electrolysis cell modules, so that 200 ns x 15 = 3 μs. Therefore, the gate signal is a square wave having a frequency corresponding to about 333 kHz. Further, since the on-time ratio G1 of the gate signal is calculated by the voltage of the water electrolysis system 100 (= output voltage of the power supply 106) / (terminal voltage of the water electrolysis cell module 102 x number of 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, ... 102n are sequentially driven based on these numerical values, the water electrolysis system 100 has a rectangular wavy terminal voltage H1 in FIG. This terminal voltage H1 fluctuates between 35.0V and 38.5V. That is, the terminal voltage H1 fluctuates in the period calculated by the period F of the gate signal / 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, ... 102n, and is output as a terminal voltage H2 of about 35.2 V for the entire water electrolysis system 100.

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 square wave. Further, since the water electrolysis cell 10 and the capacitor 14 form an RLC filter, a filtered and leveled current J2 flows through the water electrolysis system 100. As described above, the current waveforms are uniform in all the water electrolysis cell modules 102a, 102b, ... 102n, and the current flows evenly in all the water electrolysis cell modules 102a, 102b, ... 102n. .. In this way, since the current of the water electrolysis system 100 is leveled while controlling the output voltage, the current is not intermittent as in the configuration in which the voltage is controlled by simply disconnecting the water electrolysis system 100 in the prior art. Deterioration of the system 100 can be suppressed.

As described above, when controlling the water electrolysis system 100, the gate signal output to the water electrolysis cell module 102a on the most upstream side is output to the water electrolysis cell module 102b on the downstream side with a delay of a certain period of time, and further. Since this gate signal is delayed for a certain period of time and sequentially transmitted to the water electrolysis cell module 102 on the downstream side, a voltage is sequentially transmitted from the power source 106 to the water electrolysis cell modules 102a, 102b, ... 102n while being delayed for a certain period of time. It is applied. Then, in each of the water electrolysis cell modules 102 included in the water electrolysis system 100, water can be electrolyzed according to the output voltage of the power supply 106.

The voltage output from the power supply 106 may be set so that the efficiency of the power supply 106 becomes high depending on the situation of the power supply 106. For example, when the power source 106 is a solar cell, it may be set to be the maximum output voltage at the maximum power operating point according to the sunshine state and temperature of the solar cell. Specifically, the output voltage of the power supply 106 may be measured by the voltage sensor 34 provided between the terminals of the water electrolysis system 100, and the control unit 104 may set 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 controlled by MPPT of the solar cell.

According to the water electrolysis system 100, a step-down circuit is not required, the circuit configuration can be simplified, and the size and cost can be reduced. Further, a balance circuit or the like that causes a power loss is unnecessary, and the efficiency of the water electrolysis system 100 can be improved. Further, since the voltage is applied substantially evenly to the plurality of water electrolysis cell modules 102a, 102b, ... 102n, the load is not concentrated on the specific water electrolysis cell module 102, and the water electrolysis system 100 Deterioration can be suppressed.

Further, by adjusting the on-time ratio G1, it is possible to easily correspond to a desired voltage, and it is possible to improve the versatility of the water electrolysis system 100. In particular, even if a failure occurs in the water electrolysis cell modules 102a, 102b, ... 102n and the water electrolysis cell module 102 that is difficult to use occurs, the failed water electrolysis cell module 102 is excluded and normal. The water electrolysis cell module 102 can be used to accommodate the desired voltage by resetting the gate signal period F, on-time ratio G1, and delay time. That is, even if a failure occurs in the water electrolysis cell modules 102a, 102b, ... 102n, control according to the output voltage of the power supply 106 can be realized.

Further, by setting a long delay time for delaying the gate signal, the frequency of the gate signal becomes low, so that the switching frequencies of the switch element 16 and the diode 18 also become low, and the switching loss can be reduced. On the contrary, by shortening the delay time for delaying the gate signal, the frequency of the gate signal becomes high frequency, so that the frequency of voltage fluctuation becomes high, filtering becomes easy, and stable water electrolysis processing can be performed. .. It also facilitates leveling current fluctuations with an 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 according to the required specifications and performance.

In the present embodiment, the delay circuit 20 is provided in each water electrolysis cell module 102 so that the gate signal is transmitted while being delayed, but the present invention is not limited to this. For example, the delay circuit 20 may not be provided in each water electrolysis cell module 102. In this case, the gate signal may be output individually 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 control unit 104 outputs a gate signal to the water electrolysis cell modules 102a, 102b, ... 102n at regular intervals. At this time, with respect to the water electrolysis cell modules 102a, 102b, ... 102n, the water electrolysis cell modules 102a, 102b, ... ... Controls the number of water electrolysis cell modules 102 that output a gate signal to 102n at regular time intervals to connect them. 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. It suffices to control so as to make it.

With this configuration, the delay circuit 20 becomes unnecessary, the configuration of the water electrolysis system 100 can be further simplified, and the manufacturing cost and power consumption can be suppressed.

[Forced disconnection control]
Next, a 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. Further, the control unit 104 outputs a low (L) level forced connection signal to the OR element 24 of the water electrolysis cell module 102.

As a result, the low (L) level is output from the AND element 22, and the high (H) level is input to the gate terminal of the switch element 16 via the OR element 24 by the NOT element 26. 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 deal with a failure of the water electrolysis cell module 102 in the water electrolysis system 100. FIG. 10 shows a flowchart of control for failure of the water electrolysis cell module 102. Hereinafter, control when any one of the water electrolysis cell modules 102 fails will be described with reference to FIG.

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 detects the terminal voltage of the water electrolysis cell 10 included in the water electrolysis cell module 102 when a voltage is applied from the power supply 106 by the voltage sensor 30. Then, the failure of the water electrolysis cell 10 is detected according to the detection result of the voltage sensor 30. For example, when the measured voltage of the voltage sensor 30 when a voltage is applied from the power supply 106 is equal to or less than a predetermined reference value, it is determined that the water electrolysis cell 10 is out of order.

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

In step S14, the water electrolysis cell module 102 is forcibly separated. The control unit 104 outputs a low (L) level forced disconnection signal to the AND element 22 of the water electrolysis cell module 102 whose failure is determined in step S10. As a result, the selected water electrolysis cell module 102 is forcibly disconnected from the series connection and does not contribute to the electrolysis of water in the water electrolysis system 100.

By 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 module 102 included in the water electrolysis system 100. As a result, it is possible to prevent the entire water electrolysis system 100 from being stopped due to the failure of some of the water electrolysis cell modules 102. Therefore, the water electrolysis system 100 can be operated stably.

[Forced connection control]
It is also possible to perform control for forcibly connecting a selected one of a 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 high (H) level is output from the OR element 24, and the low (L) level is input to the gate terminal of the switch element 16 by the NOT element 26. Therefore, the switch element 16 is always off, and the water electrolysis cell module 102 is forcibly connected in series regardless of the state of the gate signal.

In such forced connection control, water can be forcibly electrolyzed by the water electrolysis cell 10 included in the 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 electrolysis 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)

The water electrolysis cell, the terminal for supplying power to the water electrolysis cell, the switch element connected to the terminal and connected in parallel to the water electrolysis cell, the capacitor connected in parallel to the water electrolysis cell, and the above. Water electrolysis including a diode connected in series to the water electrolysis cell between the water electrolysis cell and the switch element and connected in a direction to energize the water electrolysis cell when power is supplied from the terminal to the water electrolysis cell. A group of water electrolysis cell modules in which a plurality of cell modules are connected in series via the terminals, and
A control circuit that outputs a gate signal that drives the switch element of the water electrolysis cell module on and off to each of the water electrolysis cell modules of the water electrolysis cell module group at regular time intervals.
A water electrolysis system characterized by being equipped with. The water electrolysis system according to claim 1.
The control circuit is provided corresponding to the water electrolysis cell module, and includes a delay circuit for transmitting the gate signal with a delay of a certain period of time between adjacent water electrolysis cell modules in the water electrolysis cell module group.
The period of the gate signal is the total value of the delay times in each of the delay circuits of the water electrolysis cell module, and is input to the water electrolysis cell module in a state of being connected in series by turning off the switch element. A water electrolysis system characterized by being supplied with electric power. The water electrolysis system according to claim 1 or 2.
A water electrolysis system characterized in that the input terminal of the water electrolysis cell module group is connected to a solar cell. The water electrolysis system according to claim 3.
The solar cell maximum output control target value setting means for obtaining the target current or target voltage at which the output of the solar cell is maximized is provided.
The control circuit controls the on / off drive of the switch element so 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.
A water electrolysis cell failure detection means for detecting the failure state of the water electrolysis cell is provided.
A water electrolysis system characterized in that the switch element of the water electrolysis cell module including the water electrolysis cell in which a failure is detected by the water electrolysis cell failure detection means is maintained in an ON state.

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