Power supply system, and controller and control method thereof

Abstract

A power supply system for an electrolyzer module is provided. The electrolyzer module includes a plurality of electrolyzers, a first electrolyzer and a second electrolyzer from the plurality of electrolyzers being coupled in series. The power supply system inlcudes a DC / DC converter (1) comprising a first switch coupled with the first electrolyzer and a second switch coupled with the second electrolyzer, the first switch and the second switch being configurable to be independently operated to obtain individual control of powering of the first and the second electrolyzers, and a controller (2) configured to receive a differential measurement value indicating a difference in performances of the first and second electrolyzers and to control operation of at least one of the first and second electrolyzers by controlling switching of at least one of the first and second switches based on the differential measurement value.

Description

POWER SUPPLY SYSTEM, AND CONTROLLER AND CONTROL METHOD THEREOFTECHNICAL FILED

[0001] The present disclosure relates to a power supply system for an electrolyzer module including electrolyzers connected in series, and a method for controlling the power supply system.BACKGROUND

[0002] By exploring solutions with IGBT modules to transfer AC power to DC power for an electrolysis process in green hydrogen applications, the two-stage power conversion (i.e., AC / DC conversion and DC / DC conversion) combined with a configuration of series-connected electrolyzers (also can be called a bipolar configuration of electrolyzers) is identified as an optimal solution from a semiconductor cost point of view. However, the series-connected electrolyzers could have asymmetrical characteristics, possibly due to divergent aging status or parameters drift in volume product. In this case, the seriously aged electrolyzer generally consumes more power, which will further accelerate its aging process and lead to a shortened service life.SUMMARY

[0003] According to an embodiment of the present disclosure, a power supply system for an electrolyzer module is provided. The electrolyzer module includes a plurality of electrolyzers, and a first electrolyzer and a second electrolyzer from the plurality of electrolyzers is coupled in series. The power supply system includes: a DC / DC converter comprising a first switch coupled with the first electrolyzer and a second switch coupled with the second electrolyzer, the first switch and the second switch being configurable to be independently operated to obtain individual control ofpowering of the first and the second electrolyzers; and a controller configured to receive a differential measurement value indicating a difference in performances of the first and second electrolyzers and to control operation of at least one of the first and second electrolyzers by controlling switching of at least one of the first and second switches based on the differential measurement value.

[0004] In an example, in the case that the differential measurement value indicates the performance of the first electrolyzer is different than that of the second electrolyzer, the controller is configured to control the first switch with a first duty cycle and the second switch with a second duty cycle that is different from the first duty cycle.

[0005] In an example, the controller is configured to operate at least one of the first and second switches to power at least one of the first and second electrolyzers, such that a total hydrogen production of the first and second electrolyzers within a predetermined period of time reaches a target total hydrogen production and that a total power loss in the first and second electrolyzers is reduced within the predetermined period of time.

[0006] In an example, in the case that the difference measurement value indicates the performance of the first electrolyzer is the same as that of the second electrolyzer, the controller is configured to: control the first and second switches with the same duty cycle such that the first and second electrolyzers are operated synchronously to have the same hydrogen production duration within a predetermined period of time.

[0007] In an example, the differential measurement value is correlated with an aging state of each of the first and second electrolyzers, and wherein the controller is configured to determine whether the first and second electrolyzers are in a balanced state or an unbalanced state based on the differential measurement value.

[0008] In an example, in the case that the differential measurement value indicates that the first and second electrolyzers are in the unbalanced state, the controller is configured to: control the duty cycle of each of the first and second switches such that each of the first and second electrolyzers is powered to generate hydrogen at a predetermined percentage which corresponds to the aging state of the electrolyzer, andthat collectively the plurality of electrolyzers generate a target total hydrogen production.

[0009] In an example, in the case that the differential measurement value indicates that the first and second electrolyzers are in the unbalanced state, the controller is configured to: adjust the duty cycle of at least one of the first and second switches to compensate the loss of performance in either of the first and second electrolyzers.

[0010] In an example, in the case that the differential measurement value indicates that the first and second electrolyzers are in the unbalanced state, the controller is configured to: dynamically adjust the duty cycle of at least one of the first and second switches over a period of time until the differential measurement value indicates the first and second electrolyzers are in the balanced state.

[0011] In an example, in the case that there is a fault in one of the first and second electrolyzers, the controller is configured to: control at least one of the first and second switches to bypass the faulty electrolyzer.

[0012] In an example, the differential measurement value is determined based on one or more difference measurement values for quantitatively representing a difference between a presently measured state of the first electrolyzer and a presently measured state of the second electrolyzer.

[0013] In an example, the differential measurement value is determined based on one or more difference measurement values for quantitatively representing a difference between a presently measured state of at least one of the first and the second electrolyzers and a previously measured state of the at least one electrolyzer.

[0014] In an example, the differential measurement value is determined based on a voltage difference between a first voltage of the first electrolyzer and a second voltage of the second electrolyzer.

[0015] In an example, the differential measurement value is determined based on a current difference between a reference current and a measured current measured in a branch between a series node of the first and second electrolyzers and a connection node of the first and second switches.

[0016] In an example, the differential measurement value is determined based on a voltage difference between a reference voltage and a measured voltage measured at a series node of the first and second electrolyzers.

[0017] In an example, the DC / DC converter comprises a first output end coupled with one terminal of the first electrolyzer, a second output end coupled with one terminal of the second electrolyzer, and a third output end coupled with a series node of the first and second electrolyzers.

[0018] In an example, the DC / DC converter is a boost DC / DC converter and further comprises a first capacitor coupled with the first electrolyzer and a second capacitor coupled with the second electrolyzer; the first capacitor has a first capacitance which is predetermined for satisfying a ripple requirement of the first electrolyzer, and the second capacitor has a second capacitance which is predetermined for satisfying a ripple requirement of the second electrolyzer.

[0019] In an example, the DC / DC converter is a buck DC / DC converter and further comprises a first inductor coupled with the first electrolyzer and a second inductor coupled with the second electrolyzer; the first inductor has a first inductance which is predetermined for satisfying a ripple requirement of the first electrolyzert, and the second inductor has a second inductance which is predetermined for satisfying a ripple requirement of the second electrolyzer.

[0020] According to another embodiment of the present disclosure, a method for controlling a power supply system is provided. The method includes the steps of obtaining a differential measurement value indicating a difference in performances of the first and second electrolyzers; determineing whether the first and second electrolyzers are in a balanced state or in an unbalanced state based on the differential measurement value; in the case that it is determined the first and second electrolyzers are in the balanced state, controlling the first switch and the second switch so that the two electrolyzers are operated synchronously to have the same hydrogen production duration within a predetermined period of time; and in the case that it is determined the first and second electrolyzers are in the unbalanced state, controlling the first andsecond switches with different duty cycles, such that a total hydrogen production of the first and second electrolyzers within the predetermined period of time reaches a target total hydrogen production and that a total power loss in the first and second electrolyzers is reduced within the predetermined period of time.

[0021] In an example, the step of controlling the first and second switches with different duty cycles includes: determining one of the first and second electrolyzers that has a worse aging state based on the differential measurement value; controlling the first switch and the second switch with different duty cycles to reduce the hydrogen production duration of said one electrolyzer having a worse aging state within the predetermined period of time, and to increase the hydrogen production duration of the other electrolyzer within the predetermined time period; and dynamically adjusting the duty cycle of each switch based on the differential measurement value obtained in real time such that the loss of performance in the electrolyzer that has a worse aging state is compensated and that the difference in performances of the first and second electrolyzers is minimized.

[0022] According to yet another embodiment of the present disclosure, a controller for controlling a power supply system is provied. The controller includes one or more processors configured with processor-executable instructions to perform the method described above.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The disclosed aspects will hereinafter be described in connection with the appended drawings that are provided to illustrate but not to limit the scope of the present disclosure.

[0024] Figure 1 is a block diagram of a power supply system for an electrolyzer module according to an embodiment of the present disclosure.

[0025] Figure 2 illustrates an example of the electrolyzer module in Figure 1.

[0026] Figure 3 is an exemplary circuit of a boost DC / DC converter according to an embodiment of the present disclosure.

[0027] Figures 4A-4D illustrates exemplary operation modes of the boost DC / DC converter in Figure 3.

[0028] Figure 5 is an exemplary circuit of a buck DC / DC converter according to an embodiment of the present disclosure.

[0029] Figures 6A-6F illustrates exemplary operation modes of the buck DC / DC converter in Figure 5.

[0030] Figure 7 is a flowchart of a method for controlling a power supply system according to an embodiment of the present disclosure.

[0031] Figures 8 and 9 show examples of a main step of the method in Figured 7.DETAILED DESCRIPTION

[0032] Examples of the present disclosure provide a solution for controlling a DC / DC power converter (hereinafter referred to as DC / DC converter) to control operations of series-connected electrolyzers in a bipolar configuration based on a differential measurement value indicating difference in performance of the electrolyzers. The DC / DC converter can be a boost DC / DC converter or a buck DC / DC converter. The solution according to examples of the present disclosure can be applied to both the boost DC / DC converter and the buck DC / DC converter.

[0033] According to an example of the present disclosure, operation of each of the electrolyzers can be controlled individually depending on SOH / aging states of the electrolyzers. In this way, a flexible regulation of operation of the electrolyzers can be realized. Moreover, a total power loss of the electrolyzers can be reduced in the case of the same amount of hydrogen produced by the electrolyzers over a predetermined period of time.

[0034] According to an example of the present disclosure, a balanced state of aging of the electrolyzers can be achieved by releasing the hydrogen production stress of aged electrolyzers, for example, by adjusting duty cycles of switches of the DC / DC converter to load healthy electrolyzers to generate more hydrogen than the aged ones.

[0035] According to an example of the present disclosure, the differentialmeasurement value is used as an indicator that quantitatively measures the difference in performance of the electrolyzers, and thus the control of operation of the electrolyzers can be accurately guided by this indicator.

[0036] It is noted that, in examples of the present disclosure, the electrolyzer refers to a hydrogen electrolyzer. For example, the electrolyzer uses electricity to break water into hydrogen and oxygen in an electrolysis process. Through such an electrolysis process, the electrolyzer creates hydrogen gas.

[0037] Embodiments of the present disclosure will now be described with reference to the drawings.

[0038] Figure 1 shows a power supply system according to an embodiment of the present disclosure. The power supply system includes a DC / DC converter 1 and a controller 2 for powering the electrolyzer module 3 in a controllable manner. The electrolyzer module 3 can include a plurality of electrolyzers connected in series. In Figure 1, two electrolyzers from the plurality of electrolyzers, i.e., a first electrolyzer ELEI and a second electrolyzer ELE2, are shown.

[0039] Figure 2 shows an example of the electrolyzer module 3. Each of the first electrolyzer ELEI and the second electrolyzer ELE2 can include one or more electrolysis stacks. According to examples of the present disclosure, when both the first and second electrolyzers are at beginning of life (BOL) status, they have the same internal resistance and the same hydrogen production rate. However, after the first and second electrolyzers are operated to generate hydrogen for a period of time, they may have different internal resistances and thus different degrees of aging. According to examples of the present disclosure, the first electrolyzer and the second electrolyzer can be two electrolyzer products of the same model, and also can be two symmetrical parts of one electrolyzer product.

[0040] As shown in Figure 2, the first electrolyzer ELEI has a first terminal 311 (e.g., a positive terminal) and a second terminal 312 (e.g., a negative terminal). The second electrolyzer ELE2 has a first terminal 321 (e.g., a positive terminal) and a second terminal 322 (e.g., a negative terminal). The second terminal 312 of the first electrolyzer ELEI is coupled with the first terminal 321 of the second electrolyzerELE2. That is, the second terminal 312 of the first electrolyzer ELE is coupled with the first terminal 321 of the second electrolyzer ELE2 to form a series node of the two electrolyzers ELEI and ELE2. The series node of the two electrolyzers ELEI and ELE2 can be grounded or coupled to a reference node with a reference potential VREF.

[0041] Referring back to Figure 1, the DC / DC converter 1 has two input terminals INI and IN2 and three output terminals OUT1-OUT3. The two input terminals INI and IN2 of the DC / DC converter 1 are coupled to an AC power supply through an AC / DC converter. In addition, although not shown in Figure 1, the two input terminals INI and IN2 of the DC / DC converter 1 can also be coupled to a DC power supply through another DC / DC converter or directly coupled to the DC power supply. The first output terminal OUT1 of the DC / DC converter 1 is coupled to the first terminal of the first electrolyzer ELEI. The second output terminal OUT2 of the DC / DC converter 1 is coupled to the second terminal of the second electrolyzer ELE2. The third output terminal OUT3 of the DC / DC converter 1 is coupled to the series node of the two electrolyzers.

[0042] The controller 2 controls switches of the DC / DC converter 1 based on a differential measurement value indicating a difference in performance between the first electrolyzer ELEI and the second electrolyzer ELE2 (e.g., a difference in aging status of the two electrolyzers) to control the operation of at least one electrolyzer, such that a total power loss of the electrolyzers is reduced in the case of a target total amount of hydrogen produced by the electrolyzers over a predetermined period of time.

[0043] It is noted that, according to examples of the present disclosure, the controller 2 can be implemented by means of hardware or software or a combination of hardware and software, including code stored in a non-transitory computer-readable medium such as a memory and implemented as instructions executed by a processor. Regarding the part implemented by means of hardware, it may be implemented in an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a data signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, an electronic unit, or a combination thereof. The part implemented bysoftware may include a microcode, a program code or code segments. The software may be stored in a machine-readable storage medium, such as a memory.

[0044] According to examples of the present disclosure, the DC / DC converter 1 can be implemented as a boost DC / DC power converter (hereafter referred to as boost DC / DC converter) or a buck DC / DC power converter (hereafter referred to as buck DC / DC converter).

[0045] Figure 3 shows an exemplary circuit in which the DC / DC converter 1 is implemented as a boost DC / DC converter 11. As shown in Figure 3, the boost DC / DC converter 11 includes first and second switches SW 1 and SW2, first and second diodes 111 and 112, first and second capacitors 113 and 114, and an inductor 115. Each of the first and second switches can be implemented as including one or more switching devices (e.g., IGBTs or IGCTs). The first switch SW1 is coupled to the first electrolyzer ELEI and the second switch SW2 is coupled to the second electrolyzer ELE2. By individually controlling the on-off or duty cycle of the two switches, independent control of the operation of each electrolyzer can be achieved. Each of the first and second diodes is implemented as a reverse current preventing diode. Each of the first and second capacitors is implemented as a DC-link capacitor. The first capacitor 113 is coupled to the first electrolyzer ELEI for smoothing and filtering the DC current supplied to the first electrolyzer ELEI. The capacitance of the first capacitor is predetermined to meet the ripple requirements of the first electrolyzer ELEI . Similarly, the second capacitor 114 is coupled to the second electrolyzer ELE2 for smoothing and filtering the DC current supplied to the second electrolyzer ELE2. The capacitance of the second capacitor is predetermined to meet the ripple requirements of the second electrolyzer ELE2.

[0046] Figures 4A to 4D show examples of various combinations of on and off states of the first and second switches of the boost DC / DC converter 11 and corresponding operation modes of the first and second electrolyzers.

[0047] Figure 4A shows an example where the controller 2 controls both of the first and the second switches to be turned off. In this case, both the first and second electrolyzers are operated to produce hydrogen. The current flows from the first inputterminal INI of the boost DC / DC converter 11 into the power supply loop, flows through the first and second electrolyzers in sequence, and then flows out of the power supply loop from the second input terminal IN2 of the boost DC / DC converter 11. The direction of the current flow in the power supplying loop is shown by arrows in Figure 4A.

[0048] Figure 4B shows an example where the controller 2 controls both of the first and the second switches to be turned on. In this case, both the first and second electrolyzers are not operated to produce hydrogen. The current flows only through the first and second switches, but not through the first or second electrolyzers. The direction of the current flow in the power supplying loop is shown by arrows in Figure 4B.

[0049] Figure 4C shows an example where the controller 2 controls the first switch to be turned on and the second switch to be turned off. In this case, only the second electrolyzer is operated to produce hydrogen. The current flows from the first input terminal INI of the boost DC / DC converter 11 into the power supply loop, flows through the first switch and second electrolyzer in sequence, and then flows out of the power supply loop from the second input terminal IN2 of the boost DC / DC converter 11. The direction of the current flow in the power supplying loop is shown by arrows in Figure 4C.

[0050] Figure 4D shows an example where the controller 2 controls the first switch to be turned off and the second switch to be turned on. In this case, only the first electrolyzer is operated to produce hydrogen. The current flows from the first input terminal INI of the boost DC / DC converter 11 into the power supply loop, flows through the first electrolyzer and second switch in sequence, and then flows out of the power supply loop from the second input terminal IN2 of the boost DC / DC converter 11. The direction of the current flow in the power supplying loop is shown by arrows in Figure 4D.

[0051] Figure 5 shows an exemplary circuit in which the DC / DC converter 1 is implemented as a buck DC / DC converter 12. As shown in Figure 5, the buck DC / DC converter 12 includes first and second switches SW1 and SW2, first and second diodes121 and 122, first to fourth capacitors 125-128, and first and second inductors 123 and 124. Each of the first and second switches can be implemented as including one or more switching devices (e.g., IGBTs or IGCTs). The first switch SW1 is coupled to the frist electrolyzer ELEI and the second switch SW2 is coupled to the second electrolyzer ELE2. By individually controlling the on-off or duty cycle of the two switches, independent control of the operation of each electrolyzer can be achieved. Each of the first and second diodes is implemented as a reverse current preventing diode. Each of the first to fourth capacitors is implemented as a DC-link capacitor for smoothing and filtering the DC current supplied to one or both of the first and second electrolyzers. The first inductor 123 is coupled to the first electrolyzer ELEI and has an inductance that is predetermined to meet the ripple requirements of the first electrolyzer ELEI. Similarly, the second inductor 124 is coupled to the second electrolyzer ELE2 and has an inductance that is predetermined to meet the ripple requirements of the second electrolyzer ELE2.

[0052] Figures 6A to 6F show examples of various combinations of on and off states of the first and second switches of the buck DC / DC converter 12 and corresponding operating modes of the first and second electrolyzers.

[0053] Figure 6A shows an example where the controller 2 controls both of the first and the second switches to be turned off. In this case, both the first and second electrolyzers are operated to produce hydrogen by making use of electrical energy stored in the inductors. The current flows from the first inductor into the power supply loop, flows through the first and second electrolyzers, the second inductor, the second and the first diodes in sequence. The direction of the current flow in the power supplying loop is shown by arrows in Figure 6 A.

[0054] Figure 6B shows an example where the controller 2 controls both of the first and the second switches to be turned on. In this case, both the first and second electrolyzers are operated to produce hydrogen. The current flows from the first input terminal INI of the buck DC / DC converter 12 into the power supply loop, flows through the first and second electrolyzers in sequence, and then flows out of the power supply loop from the second input terminal IN2 of the buck DC / DC converter 12. Thedirection of the current flow in the power supplying loop is shown by arrows in Figure 6B.

[0055] Figure 6C shows an example where the controller 2 controls the first switch to be turned on and the second switch to be turned off. In this case, only the first electrolyzer is operated to produce hydrogen. The current flows from the first input terminal INI of the buck DC / DC converter 12 into the power supply loop, flows through the first electrolyzer, and then flows out of the power supply loop from the second input terminal IN2 of the buck DC / DC converter 12. The direction of the current flow in the power supplying loop is shown by arrows in Figure 6C.

[0056] Figure 6D shows an example where the controller 2 controls both of the first and the second switches to be turned off. In this case, only the first electrolyzer is operated to produce hydrogen by making use of electrical energy stored in the first inductor. This might happen when the second electrolyzer fails or when the second inductor has no stored electrical energy. The current flows from the first inductor into the power supply loop, flows through the first electrolyzer and the first diodes in sequence. The direction of the current flow in the power supplying loop is shown by arrows in Figure 6D.

[0057] Figure 6E shows an example where the controller 2 controls the first switch to be turned off and the second switch to be turned on. In this case, only the second electrolyzer is operated to produce hydrogen. The current flows from the first input terminal INI of the buck DC / DC converter 12 into the power supply loop, flows through the second electrolyzer, and then flows out of the power supply loop from the second input terminal IN2 of the buck DC / DC converter 12. The direction of the current flow in the power supplying loop is shown by arrows in Figure 6E.

[0058] Figure 6F shows an example where the controller 2 controls both of the first and the second switches to be turned off. In this case, only the second electrolyzer is operated to produce hydrogen by making use of electrical energy stored in the second inductor. This might happen when the first electrolyzer fails or when the first inductor has no stored electrical energy. The current flows through the second electrolyzer, the second inductor and the second diode in sequence. The direction of the current flow inthe power supplying loop is shown by arrows in Figure 6F.

[0059] It is noted that, in Figure 3, Figures 4A-4D, Figured 5 and Figures 6A-6F, although the series node of the two electrolyzers is grounded, it can also be connected to a reference point, especially in situations where the differential measurement value is obtained by using only one voltage sensor.

[0060] Further to examples the power supply system described above, examples of obtaining the differential measurement value are now described. According to examples of the present disclosure, the differential measurement value can be used to determine whether the first and second electrolyzers are in a balanced state or an unbalanced state. The differential measurement value can also be used to indicate changes in aging status of either of the first and second electrolyzers. This differential measurement value can be obtained based on a voltage difference or a current difference. Examples of measuring the differential voltage or the differential current to obtain the differential measurement value are described below. It is noted that these examples are applicable to both the above-mentioned boost DC / DC converter 11 and the buck DC / DC converter 12. It is noted that the following measurement methods can be used in combination.

[0061] In the description of some examples below, exemplary arrangements of one or more current sensors and exemplary arrangements of one or more voltage sensors are introduced, but the present disclosure is not limited thereto. The voltage sensors or current sensors can be arranged in any manner that can measure the required voltage or current.

[0062] In a first example, two voltage sensors, i.e., a first voltage sensor and a second voltage sensor, are used to measure two present voltages. The present states of the two electrolyzers can be known from the two present voltages. In this example, the differential measurement value is obtained by calculating a voltage difference based on the two measured voltages. The measurement method of this example is suitable for the situation where both the first and second electrolyzers are operated to produce hydrogen, for examples, the situation shown in Figure 4A or Figure 6A.

[0063] According to an embodiment of the first example, the first voltage sensormeasures a first DC voltage across the first electrolyzer, and the second voltage sensor measures a second DC voltage across the second electrolyzer. The controller 2 calculates a voltage difference between the two measured voltages, for example, subtracting the first DC voltage from the second DC voltage. When the voltage difference is zero, the controller 2 determines that the two electrolyzers have the same aging degree and are in a balanced state. When the voltage difference is greater than zero, the controller 2 determines that the aging of the first electrolyzer is more serious than that of the second electrolyzer and the two electrolyzers are in an unbalanced state. When the voltage difference is less than zero, the controller 2 determines that the aging of the second electrolyzer is more serious than that of the first electrolyzer and the two electrolyzers are in an unbalanced state.

[0064] According to another embodiment of the first example, the first voltage sensor measures the first DC voltage across the first electrolyzer, and the second voltage sensor measures a total DC voltage across the first and second electrolyzers. The controller 2 calculates the second DC voltage across the second electrolyzer based on the two measured voltages, and then determines whether the two electrolyzers are in a balanced state or an unbalanced state based on the first DC voltage and the second DC voltage using a similar method as described above.

[0065] According to yet another embodiment of the first example, the first voltage sensor measures the second DC voltage across the second electrolyzer, and the second voltage sensor measures the total DC voltage across the first and second electrolyzers. The controller 2 calculates the first DC voltage across the first electrolyzer based on the two measured voltages, and then determines whether the two electrolyzers are in a balanced state or an unbalanced state based on the first DC voltage and the second DC voltage using a similar method as described above.

[0066] In a second example, one current sensor is used to measure a present current on a branch. That is to say, the said one current sensor is arranged in the branch. The branch is a branch between a connection node of the two switches SW 1 and SW2 and the series node of the two electrolyzers ELEI and ELE2 in the case of the boost DC / DC converter 11 as shown in Figure 3. The branch is a branch between a connection nodeof the two diodes 121 and 122 and the series node of the two electrolyzers ELEI and ELE2 in the case of the buck DC / DC converter 12 as shown in Figure 5. There should be no current flowing through the branch if the two electrolyzers are in a balanced state, and there will be a current flowing through the branch if the two electrolyzers are in an unbalanced state. In this example, the differential measurement value can be obtained based on a current difference between the measured current and a zero current. When the value of the current difference is equal to zero, the controller 2 determines that the two electrolyzers are in a balanced state. When the value of the current difference is not equal to zero, the controller 2 determines that the two electrolyzers are in an unbalanced state. The measurement method of this example is suitable for the situation where both the first and second electrolyzers are operated to produce hydrogen, for examples, the situation shown in Figure 4A or Figure 6A.

[0067] Additionally, in the second example, in the case that the current difference is not equal to zero and the two electrolyzers are in an unbalanced state, the differential measurement value also can be a current difference between a presently measured current and a previously measured current or a reference current. In this case, the differential measurement value can indicate whether the difference in aging status between the two electrolyzers decreases or increases. For example, if the differential measurement value increases, it means that the difference in aging status between the two electrolyzers increases. If the differential measurement value decreases, it means that the difference in aging status between the two electrolyzers decreases.

[0068] In a third example, one voltage sensor is used to measure a voltage between the series node of the electrolyzers and the reference node. The measurement method of this example is applicable to situations where the series node is not grounded. When the two electrolyzers are in a balanced state, the value of the voltage between the series node of the electrolyzers and the reference node (i.e., the measured voltage) should be equal to a pre-fixed value. In this example, the differential measurement value can be obtained based on a voltage difference between the measured voltage and a reference voltage having the pre-fixed value. When the value of the voltage difference is equal to zero, the controller 2 determines that the two electrolyzers are in a balanced state.When the value of the voltage difference is not equal to zero, the controller 2 determines that the two electrolyzers are in an unbalanced state. The measurement method of this example is suitable for the situation where both the first and second electrolyzers are operated to produce hydrogen, for examples, the situation shown in Figure 4A or Figure 6A.

[0069] Additionally, in the third example, in the case that the voltage difference is not equal to zero and the two electrolyzers are in an unbalanced state, the differential measurement value also can be a voltage difference between a presently measured voltage and a previously measured voltage or the reference voltage. In this case, the differential measurement value can indicate whether the difference in aging status between the two electrolyzers decreases or increases. For example, if the differential measurement value increases, it means that the difference in aging status between the two electrolyzers increases. If the differential measurement value decreases, it means that the difference in aging status between the two electrolyzers decreases.

[0070] Additionally, in a situation where one of the first and second electrolyzers is operated to generate hydrogen (e.g., the situation shown in Figure 4A, 4B, 6C, 6D, 6E or 6F), the differential measurement value can be obtained based on a voltage difference between a measured voltage of said one electrolyzer and a reference voltage or based on a current difference between a measured current of said one electrolyzer and a reference current. In this case, the rate of change of the differential measurement value can be used to indicate the rate of aging of said one electrolyzer. For example, when the rate of change of the differential measurement value increases, it means the rate of aging of said one electrolyzer increases. When the rate of change of the differential measurement value decreases, it means the rate of aging of said one electrolyzer decreases.

[0071] Figure 7 is a flowchart of a method 700 for controlling a power supply system according to an embodiment of the present disclosure. The method 700 can be performed by the controller 2 described above and can be applied to the power supply system described above, and thus various features of the power supply system described above are also applicable to the method 700.

[0072] At block 702, the controller 2 obtains a differential measurement value indicating a difference in performances of the first and second electrolyzers. Regarding examples of the obtaining of the differential measurement value, please refer to related examples described above.

[0073] At block 704, the controller 2 determines whether the first and second electrolyzers are in a balanced state or in an unbalanced state based on the differential measurement value. Regarding examples of the determining step, please refer to related examples described above.

[0074] If it is determined the first and second electrolyzers are in the balanced state, the method 700 proceeds to block 706.

[0075] At block 706, the controller 2 controls the first switch and the second switch so that the two electrolyzers are operated synchronously. For example, the controller 2 controls the first switch and the second switch with the same duty cycle, so that the two electrolyzers are operated to have the same hydrogen production duration within a predetermined period of time.

[0076] If it is determined the first and second electrolyzers are in the unbalanced state, the method 700 proceeds to block 708.

[0077] At block 708, the controller 2 controls at least one of the first and second switches based on the differential measurement value such that a total hydrogen production of the first and second electrolyzers within a predetermined period of time reaches a target total hydrogen production and that a total power loss in the first and second electrolyzers is reduced within the predetermined period of time.

[0078] Examples of the controlling step of block 708 are introduced below.

[0079] Figure 8 is a flowchart of an exemplary implementation 800 of the control step of block 708.

[0080] At block 802, the controller 2 determines one of the first and second electrolyzers that has a worse aging state based on the differential measurement value. Regarding examples of the determining step, please refer to related examples described above.

[0081] At block 804, the controller 2 controls the first switch and the second switchwith different duty cycles to reduce the hydrogen production duration of said one electrolyzer having a worse aging state within the predetermined time period, and to increase the hydrogen production duration of the other electrolyzer within the predetermined time period. In this way, the loss of performance of the severely aged electrolyzer can be compensated by the lightly aged electrolyzer.

[0082] For example, in the case of using the boost DC / DC converter 11 and the first electrolyzer being the severely aged one, the controller 2 controls the first switch with a greater duty cycle (e.g., 70%) and the second switch with a smaller duty cycle (e.g., 30%) such that the electrolyzers are operated in the situation of Figure 4C for a longer time than in the situation of Figure 4D.

[0083] For example, in the case of using the buck DC / DC converter 12 and the first electrolyzer being the severely aged one, the controller 2 controls the second switch with a greater duty cycle (e.g., 70%) and the first switch with a smaller duty cycle (e.g., 30%) such that the electrolyzers are operated in the situation of Figure 4E for a longer time than in the situation of Figure 6C.

[0084] At block 806, the controller 2 dynamically adjusts the duty cycle of each switch and detects the differential measurement value in real time.

[0085] At block 808, once the controller 2 detects a differential measurement value which indicates the first and second electrolyzers are in a balanced state, the controller 2 controls the first switch and the second switch with the same duty cycle.

[0086] Figure 9 is a flowchart of another exemplary implementation 900 of the control step of block 708.

[0087] At block 902, the controller 2 determines a first average current of the first electrolyzer and a second average current of the second electrolyzer, such that, within the predetermined time period, the sum of the first average current and the second average current is equal to a total current corresponding to the target total hydrogen and that the total power loss in the first and second electrolyzers based on the first and second average currents and the inner resistances of the first and second electrolyzers is minimized.

[0088] At block 904, the controller 2 determines the duty cycles of the first andsecond switches according to the first and second average currents.

[0089] At block 906, the controller 2 controls the first and second switches according to the determined duty cycles.

[0090] Additionally, in the case where only one electrolyzer is operated to produce hydrogen, when it is determined that the aging speed of the electrolyzer increases based on the differential measurement value, the controller 2 can control a corresponding switch to reduce the DC voltage provided to the electrolyzer. In this way, the load rate of the electrolyzer is reduced and the aging of the electrolytic can be delayed.

[0091] Additionally, in the case where there is a fault in one of the two electrolyzer, the faulty electrolyzer can be bypassed by controll the switches.

[0092] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalent transformations to the elements of the various aspects of the present disclosure, which are known or to be apparent to those skilled in the art, are intended to be covered by the claims.

Claims

WHAT IS CLAIMED IS:

1. A power supply system for an electrolyzer module, the electrolyzer module comprising a plurality of electrolyzers, a first electrolyzer and a second electrolyzer from the plurality of electrolyzers being coupled in series, the power supply system comprising: a DC / DC converter comprising a first switch coupled with the first electrolyzer and a second switch coupled with the second electrolyzer, the first switch and the second switch being configurable to be independently operated to obtain individual control of powering of the first and the second electrolyzers; and a controller configured to receive a differential measurement value indicating a difference in performances of the first and second electrolyzers and to control operation of at least one of the first and second electrolyzers by controlling switching of at least one of the first and second switches based on the differential measurement value.

2. The power supply system of claim 1, wherein, in the case that the differential measurement value indicates the performance of the first electrolyzer is different than that of the second electrolyzer, the controller is configured to control the first switch with a first duty cycle and the second switch with a second duty cycle that is different from the first duty cycle.

3. The power supply system of claim 1, wherein the controller is configured to operate at least one of the first and second switches to power at least one of the first and second electrolyzers, such that a total hydrogen production of the first and second electrolyzers within a predetermined period of time reaches a target total hydrogen production and that a total power loss in the first and second electrolyzers is reduced within the predetermined period of time.

4. The power supply system of claim 1, wherein, in the case that the difference measurement value indicates the performance of the first electrolyzer is the same as that of the second electrolyzer, the controller is configured to: control the first and second switches with the same duty cycle such that the first and second electrolyzers are operated synchronously to have the same hydrogen production duration within a predetermined period of time.

5. The power supply system of claim 1, wherein the differential measurement value is correlated with an aging state of each of the first and second electrolyzers, and wherein the controller is configured to determine whether the first and second electrolyzers are in a balanced state or an unbalanced state based on the differential measurement value.

6. The power supply system of claim 5, wherein, in the case that the differential measurement value indicates that the first and second electrolyzers are in the unbalanced state, the controller is configured to: control the duty cycle of each of the first and second switches such that each of the first and second electrolyzers is powered to generate hydrogen at a predetermined percentage which corresponds to the aging state of the electrolyzer, and that collectively the plurality of electrolyzers generate a target total hydrogen production.

7. The power supply system of claim 5, wherein, in the case that the differential measurement value indicates that the first and second electrolyzers are in the unbalanced state, the controller is configured to: adjust the duty cycle of at least one of the first and second switches to compensate the loss of performance in either of the first and second electrolyzers.

8. The power supply system of claim 5, wherein, in the case that the differential measurement value indicates that the first and second electrolyzers are in the unbalanced state, the controller is configured to: dynamically adjust the duty cycle of at least one of the first and second switches over a period of time until the differential measurement value indicates the first and second electrolyzers are in the balanced state.

9. The power supply system of any of claims 1-8, wherein, in the case that there is a fault in one of the first and second electrolyzers, the controller is configured to: control at least one of the first and second switches to bypass the faulty electrolyzer.

10. The power supply system of any of claims 1-9, wherein the differential measurement value is determined based on one or more difference measurement values for quantitatively representing a difference between a presently measured state of the first electrolyzer and a presently measured state of the second electrolyzer.

11. The power supply system of any of claims 1-9, wherein the differential measurement value is determined based on one or more difference measurement values for quantitatively representing a difference between a presently measured state of at least one of the first and the second electrolyzers and a previously measured state of the at least one electrolyzer.

12. The power supply system of claim 1-9, wherein the differential measurement value is determined based on a voltage difference between a first voltage of the first electrolyzer and a second voltage of the second electrolyzer.

13. The power supply system of claim 1-9, wherein the differential measurement value is determined based on a current difference between a reference current and a measured current measured in a branch between a series node of the first and second electrolyzers and a connection node of the first and second switches.

14. The power supply system of claim 1-9, wherein the differential measurement value is determined based on a voltage difference between a reference voltage and a measured voltage measured at a series node of the first and second electrolyzers.

15. The power supply system of claim 1, wherein the DC / DC converter comprises a first output end coupled with one terminal of the first electrolyzer, a second output end coupled with one terminal of the second electrolyzer, and a third output end coupled with a series node of the first and second electrolyzers.

16. The power supply system of any of claims 1-15, wherein the DC / DC converter is a boost DC / DC converter and further comprises a first capacitor coupled with the first electrolyzer and a second capacitor coupled with the second electrolyzer; the first capacitor has a first capacitance which is predetermined for satisfying a ripple requirement of the first electrolyzer, and the second capacitor has a second capacitance which is predetermined for satisfying a ripple requirement of the second electrolyzer.

17. The power supply system of any of claims 1-15, wherein the DC / DC converter is a buck DC / DC converter and further comprises a first inductor coupled with the first electrolyzer and a second inductor coupled with the second electrolyzer; the first inductor has a first inductance which is predetermined for satisfying a ripple requirement of the first electrolyzert, andthe second inductor has a second inductance which is predetermined for satisfying a ripple requirement of the second electrolyzer.

18. A method for controlling a power supply system of any of claims 1-17, comprising: obtaining a differential measurement value indicating a difference in performances of the first and second electrolyzers; determineing whether the first and second electrolyzers are in a balanced state or in an unbalanced state based on the differential measurement value; in the case that it is determined the first and second electrolyzers are in the balanced state, controlling the first switch and the second switch so that the two electrolyzers are operated synchronously to have the same hydrogen production duration within a predetermined period of time; and in the case that it is determined the first and second electrolyzers are in the unbalanced state, controlling the first and second switches with different duty cycles, such that a total hydrogen production of the first and second electrolyzers within the predetermined period of time reaches a target total hydrogen production and that a total power loss in the first and second electrolyzers is reduced within the predetermined period of time.

19. The method of claim 18, the step of controlling the first and second switches with different duty cycles comprises: determining one of the first and second electrolyzers that has a worse aging state based on the differential measurement value; controlling the first switch and the second switch with different duty cycles to reduce the hydrogen production duration of said one electrolyzer having a worse aging state within the predetermined period of time, and to increase the hydrogen production duration of the other electrolyzer within the predetermined time period; anddynamically adjusting the duty cycle of each switch based on the differential measurement value obtained in real time such that the loss of performance in the electrolyzer that has a worse aging state is compensated and that the difference in performances of the first and second electrolyzers is minimized.

20. A controller for controlling a power supply system, comprising one or more processors configured with processor-executable instructions to perform the method of any of claims 18-19.

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