Direct-current hydrogen production converter and control method and device of direct-current hydrogen production converter

Abstract

The invention relates to the technical field of renewable energy sources, and discloses a direct-current hydrogen production converter and a control method and device of the direct-current hydrogen production converter. The direct-current hydrogen production converter comprises a dual-active bridge branch and a step-down conversion branch, the dual-active bridge branch is connected in parallel with the step-down conversion branch; the dual active bridge branch and the step-down conversion branch are used for reducing the first direct-current voltage into second direct-current voltage, and the second direct-current voltage is used for supporting the hydrogen production electrolytic cell to work; and the electric energy output by the dual-active bridge branch and the electric energy output by the step-down conversion branch are complementary, so that the fluctuation of the electric energy output by the direct-current hydrogen production converter is reduced. According to the direct-current hydrogen production converter, high-power low-current ripple output can be realized, and a hydrogen production electrolyzer is supported to work.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy, and particularly to a DC hydrogen production converter, a control method and device for the DC hydrogen production converter. Background Art

[0002] In the context of the global energy transition, renewable energy is gradually becoming the core development direction in the energy field due to its many significant advantages. However, renewable energy has the characteristics of intermittency and instability. Taking solar energy as an example, its power generation is affected by factors such as day and night alternation and weather changes. Wind power generation depends on the magnitude and stability of the wind. This unstable power output poses a huge challenge to subsequent energy utilization. Hydrogen production, as an efficient energy storage and conversion method, provides a feasible way to solve the problem of renewable energy consumption. By electrolyzing water to produce hydrogen, unstable renewable energy can be converted into chemical energy and stored in hydrogen. In a DC hydrogen production system, the DC hydrogen production converter provides electrical energy for the electrolyzer and plays a crucial role in the hydrogen production efficiency of the electrolyzer. Therefore, how to design a DC hydrogen production converter with low ripple and high power to improve the hydrogen production efficiency has become the current focus of attention. Summary of the Invention

[0003] In view of this, the present invention provides a DC hydrogen production converter, a control method and device for the DC hydrogen production converter to solve the problem of controlling the DC hydrogen production converter of renewable energy.

[0004] In a first aspect, the present invention provides a DC hydrogen production converter, which includes: a dual active bridge branch and a buck converter branch; the dual active bridge branch is connected in parallel with the buck converter branch; the dual active bridge branch and the buck converter branch are used to reduce a first DC voltage to a second DC voltage, and the second DC voltage is used to support the operation of the hydrogen production electrolyzer; the electrical energy output by the dual active bridge branch and the electrical energy output by the buck converter branch are complementary to reduce the power fluctuation of the electrical energy output by the DC hydrogen production converter.

[0005] Through the DC hydrogen production converter provided by this embodiment, during the operation of the dual active bridge branch and the buck converter branch, due to the differences in their circuit structures and control methods, the fluctuation characteristics of the output voltage are also different. When the electric energy output by the two is complementary, the peaks and valleys of their respective voltage ripples can cancel each other out to a certain extent. For example, if the output voltage of the dual active bridge branch has a relatively high peak at a certain moment, while the output voltage of the buck converter branch is at a relatively low level at this time, after the two are superimposed, the peak of the overall output voltage will be pulled down, effectively reducing the ripple of the output voltage, providing a more stable DC voltage for the hydrogen production electrolyzer, and being beneficial to improving the electrolysis efficiency and extending the service life of the electrolyzer electrodes. Similarly, through the complementary effect, the dual active bridge branch and the buck converter branch also reduce the output current fluctuation of the DC hydrogen production converter. In addition, in the DC hydrogen production converter, the dual active bridge branch and the buck converter branch cooperate with each other, and can flexibly adjust the working states of the dual active bridge branch and the buck converter branch to achieve optimized energy management and enhance the reliability of the DC hydrogen production converter. For example, when one of the branches fails or malfunctions, the other branch can maintain the operation of the system to a certain extent, improving the reliability and fault tolerance of the entire DC hydrogen production converter system. In this way, by stabilizing the power fluctuation of the output of the DC hydrogen production converter, on the one hand, it can reduce the energy damage during the electrolysis process of the electrolyzer, improve the energy utilization rate, and reduce the hydrogen production cost. On the other hand, it can enhance the stability and service life of the electrolyzer, meeting the usage requirements of high-demand scenarios.

[0006] In an alternative embodiment, the dual active bridge branch is configured to reduce the first DC voltage to a second DC voltage; the buck converter branch is configured to reduce the fluctuation of the electric energy output by the dual active bridge branch.

[0007] Through the above embodiment, the dual active bridge branch can effectively reduce the relatively high first DC voltage to the second DC voltage suitable for the operation of the hydrogen production electrolyzer, providing working voltage support for the hydrogen production electrolyzer. At the same time, the bidirectional power transmission ability of the dual active bridge branch can also achieve energy feedback when necessary, improving the energy utilization rate. The buck converter branch can process the electric energy output by the dual active bridge branch, reduce its fluctuation, help improve the quality of the electric energy input to the hydrogen production electrolyzer, and reduce problems such as a decrease in hydrogen production efficiency and an increase in equipment loss caused by power fluctuation, extend the service life of the hydrogen production equipment, and improve the stability and reliability of the hydrogen production process.

[0008] In an alternative embodiment, the DC hydrogen production converter further includes a filter branch; the filter branch is connected in series with the dual active bridge branch, and the series-connected branch is connected in parallel with the buck converter branch.

[0009] Through the above embodiments, during the operation of the dual-active bridge branch, due to the high-frequency operation of the switching devices, rich harmonics will be generated. After the filter branch is connected in series with the dual-active bridge branch, it can effectively suppress these harmonics, reduce the harmonic content in the output current and voltage, and provide a DC power closer to the ideal for the hydrogen production electrolyzer. At the same time, there may be certain voltage and current fluctuations in the electrical energy output by the dual-active bridge branch. The filter branch can smooth these fluctuations, make the output voltage and current more stable, reduce the voltage spikes and current mutations, and improve the stability of the electrical energy output by the DC hydrogen production converter.

[0010] In an alternative embodiment, the dual-active bridge branch includes a first capacitor, a first H-bridge converter, a first inductor, a high-frequency isolation transformer, and a second H-bridge converter; the input terminals of the first H-bridge converter are connected to both ends of the first capacitor; one output terminal of the first H-bridge converter is connected to one end of the primary winding of the high-frequency isolation transformer through the first inductor; the other end of the primary winding of the high-frequency isolation transformer is connected to the other output terminal of the first H-bridge converter; the secondary winding of the high-frequency isolation transformer is connected to the input terminal of the second H-bridge converter.

[0011] Through the above embodiments, in the dual-active bridge branch, the first H-bridge converter and the second H-bridge converter cooperate with each other, enabling the dual-active bridge branch to achieve bidirectional power transmission. In the case of unstable renewable energy power generation, when the power generation is excessive, the energy can be transmitted from the first H-bridge converter through the first inductor and the high-frequency isolation transformer to the second H-bridge converter to supply power to the hydrogen production electrolyzer; when the power generation is insufficient, the first inductor can reverse-transmit the energy to the first H-bridge converter side, realizing flexible energy allocation and improving the energy utilization efficiency. The high-frequency isolation transformer electrically isolates the primary and secondary sides of the circuit, effectively preventing electrical faults in the primary circuit from being conducted to the secondary side, and ensuring the safe operation of secondary-side devices such as the hydrogen production electrolyzer. In addition, the high-frequency isolation transformer can also perform voltage matching and transformation according to the turns ratio of the transformer. Therefore, by designing the turns ratio of the transformer, the input DC voltage can be converted into a DC voltage suitable for the operation of the hydrogen production electrolyzer, meeting the voltage requirements of different hydrogen production processes and enhancing the applicability of the DC hydrogen production converter.

[0012] In an alternative embodiment, the buck conversion branch includes a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a first diode, a second diode, a second inductor, and a second capacitor; the emitter of the insulated gate bipolar transistor is connected to the positive electrode of the diode, and the collector of the insulated gate bipolar transistor is connected to the negative electrode of the diode; the emitter of the first insulated gate bipolar transistor is respectively connected to the collector of the second insulated gate bipolar transistor and one end of the second inductor; the other end of the second inductor is connected to one end of the second capacitor; the other end of the second capacitor is connected to the emitter of the second insulated gate bipolar transistor; the collector of the first insulated gate bipolar transistor and the emitter of the second insulated gate bipolar transistor serve as the input end of the buck conversion branch; both ends of the second capacitor serve as the output end of the buck conversion branch.

[0013] Through the above embodiment, in the buck conversion branch, the insulated gate bipolar transistor features fast switching speed and high control precision. By controlling the on and off of the insulated gate bipolar transistor, the output voltage and current can be conveniently adjusted to adapt to different load requirements and working conditions. This flexible control method enables the buck conversion branch to operate efficiently under different working conditions, improving the adaptability and efficiency of the entire DC hydrogen production converter.

[0014] In an alternative embodiment, the filtering branch includes a first resistor and a third capacitor.

[0015] In a second aspect, the present invention provides a control method for a DC hydrogen production converter. This method is used for the above DC hydrogen production converter and includes:

[0016] Obtain a first current; the first current is the output current of the buck conversion branch in the DC hydrogen production converter;

[0017] Determine the reference current corresponding to the first current; the reference current corresponding to the first current is obtained based on a second current and the reference current corresponding to the second current; the second current is the output current of the dual active bridge branch in the DC hydrogen production converter;

[0018] Control the buck conversion branch based on the first current and the reference current corresponding to the first current.

[0019] Through the control method of the DC hydrogen production converter provided in this embodiment, in the DC hydrogen production converter, the dual active bridge branch and the buck conversion branch jointly supply power to the hydrogen production electrolytic cell. When determining the reference current of the buck conversion branch, referring to the output current of the dual active bridge branch helps to suppress the fluctuation of the first current, can effectively reduce the ripple of the output current of the DC hydrogen production converter, thereby ensuring a stable output current, reducing the impact on the electrolytic cell electrodes, improving the electrolysis efficiency and electrode life, and further enhancing the stability and reliability of the entire hydrogen production process.

[0020] In an alternative embodiment, determining the reference current corresponding to the first current includes:

[0021] Determining the deviation of the second current; the deviation of the second current is the difference between the reference current corresponding to the second current and the second current;

[0022] Taking the difference between the initial reference current corresponding to the first current and the deviation as the reference current corresponding to the first current.

[0023] Through the above embodiment, considering the deviation of the second current when determining the reference current corresponding to the first current is equivalent to introducing a feedback correction mechanism. For the buck conversion branch, the accuracy of its output current is crucial for the stable operation of the hydrogen production electrolyzer. By continuously correcting the reference current according to the second current deviation, the error between the first current and the ideal value in the steady state can be effectively reduced. This method of adjusting the reference current based on the deviation can continuously correct this deviation, keep the first current within a high-precision range all the time, provide a stable and accurate current supply for the hydrogen production electrolyzer, and improve the hydrogen production efficiency and quality.

[0024] In an alternative embodiment, controlling the buck conversion branch based on the first current and the reference current corresponding to the first current includes:

[0025] Controlling the buck conversion branch based on the first current, the reference current corresponding to the first current, and a proportional-integral regulator.

[0026] In an alternative embodiment, the dual active bridge branch includes a first capacitor, a first H-bridge converter, a first inductor, a high-frequency isolation transformer, and a second H-bridge converter; the input terminals of the first H-bridge converter are connected to both ends of the first capacitor; one output terminal of the first H-bridge converter is connected to one end of the primary winding of the high-frequency isolation transformer through the first inductor; the other end of the primary winding of the high-frequency isolation transformer is connected to the other output terminal of the first H-bridge converter; the secondary winding of the high-frequency isolation transformer is connected to the input terminal of the second H-bridge converter; there is a phase difference between the drive pulses of the switching tubes in the first H-bridge converter and the corresponding switching tubes in the second H-bridge converter;

[0027] The method further includes:

[0028] Using a single-phase-shift control algorithm to control the electric energy output by the dual active bridge branch by adjusting the phase difference.

[0029] Through the above embodiments, the single-phase-shift control algorithm can adjust the phase difference in real time according to the load change and input voltage fluctuation, so as to stabilize the output voltage and current of the dual-active-bridge branch. The stable voltage and current output helps to maintain the stability of the chemical reaction in the electrolyzer, improve the hydrogen production efficiency, reduce the loss of the electrodes, and extend the service life of the electrolyzer. For example, when the load suddenly increases, the single-phase-shift control algorithm can quickly adjust the phase difference, increase the power output, and ensure the stability of the output voltage and current.

[0030] In a third aspect, the present invention provides a control device for a DC hydrogen production converter, which is used for the above DC hydrogen production converter. The device includes:

[0031] An acquisition module, configured to acquire a first current; the first current is the output current of the buck conversion branch in the DC hydrogen production converter;

[0032] A determination module, configured to determine a reference current corresponding to the first current; the reference current corresponding to the first current is obtained based on a second current and a reference current corresponding to the second current; the second current is the output current of the dual-active-bridge branch in the DC hydrogen production converter;

[0033] A control module, configured to control the buck conversion branch based on the first current and the reference current corresponding to the first current.

[0034] Through the device provided in this embodiment, in the DC hydrogen production converter, the dual-active-bridge branch and the buck conversion branch jointly supply power to the hydrogen production electrolyzer. When determining the reference current of the buck conversion branch, referring to the output current of the dual-active-bridge branch helps to suppress the fluctuation of the first current, can effectively reduce the ripple of the output current of the DC hydrogen production converter, thereby ensuring a stable output current, reducing the impact on the electrolyzer electrodes, improving the electrolysis efficiency and electrode life, and further enhancing the stability and reliability of the entire hydrogen production process.

[0035] In a fourth aspect, the present invention provides a computer device, including: a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to execute the control method of the DC hydrogen production converter according to the second aspect or any corresponding embodiment thereof.

[0036] In a fifth aspect, the present invention provides a computer-readable storage medium, on which computer instructions are stored, and the computer instructions are used to cause a computer to execute the control method of the DC hydrogen production converter according to the second aspect or any corresponding embodiment thereof.

[0037] In a sixth aspect, the present invention provides a computer program product including computer instructions for causing a computer to execute the control method of the DC hydrogen production converter according to the second aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 is a schematic flowchart of a control method for a DC hydrogen production converter according to an embodiment of the present invention;

[0040] Figure 2 is a schematic diagram of six working modes according to an embodiment of the present invention;

[0041] Figure 3 is a schematic diagram of the transmission power characteristics of the dual-active bridge branch 1 according to an embodiment of the present invention;

[0042] Figure 4 is a flowchart of a control method for a DC hydrogen production converter according to an embodiment of the present invention;

[0043] Figure 5 is a schematic diagram of the control of a DC hydrogen production converter according to an embodiment of the present invention;

[0044] Figure 6 is an output current waveform diagram of a dual-active bridge unit hydrogen production converter in the related art according to an embodiment of the present invention;

[0045] Figure 7 is an output voltage waveform diagram of a dual-active bridge unit hydrogen production converter in the related art according to an embodiment of the present invention;

[0046] Figure 8 is an output current waveform diagram of the dual-active bridge branch in a DC hydrogen production converter according to an embodiment of the present invention;

[0047] Figure 9 is an output voltage waveform diagram of the dual-active bridge branch in a DC hydrogen production converter according to an embodiment of the present invention;

[0048] Figure 10 is an output current waveform diagram of the buck conversion branch in a DC hydrogen production converter according to an embodiment of the present invention;

[0049] Figure 11is an output voltage waveform diagram of a step-down conversion branch in a DC hydrogen production converter according to an embodiment of the present invention;

[0050] Figure 12 is a waveform diagram of the total output current of the direct current hydrogen production converter according to an embodiment of the present invention;

[0051] Figure 13 It is a structural schematic diagram of a control device of a direct current hydrogen production converter according to an embodiment of the present invention;

[0052] Figure 14 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0054] First, the application scenarios of the embodiments of the present application are exemplarily introduced.

[0055] With the rapid development of social economy, the traditional energy system based on fossil energy has fallen into the dual dilemma of resource depletion and environmental pollution. In the context of global energy transformation, renewable energy has attracted more and more attention. However, due to the intermittent and unstable nature of wind and solar energy, effective energy storage solutions are urgently needed. Hydrogen, as a high-energy-density energy storage medium, can effectively solve this problem. With the continuous development of hydrogen production technology and the continuous reduction of costs, hydrogen energy is very likely to be applied on a large scale in the future, injecting new impetus into optimizing the energy structure and strengthening environmental protection.

[0056] In the field of hydrogen production, DC hydrogen production converters are of great significance, and their performance is directly related to the efficiency and cost of hydrogen production. Low ripple converters can significantly reduce energy loss in the electrolysis process, improve energy utilization, and effectively reduce the cost of hydrogen production. Not only that, DC hydrogen production converters can also enhance the stability of electrolyzer operation, extend the service life of electrolyzers, and meet the use requirements of various occasions with strict energy supply requirements. Therefore, how to design DC hydrogen production converters to improve hydrogen production efficiency has become a focus of attention.

[0057] In view of this, the embodiments of the present application provide a DC hydrogen production converter and a control method for a DC hydrogen production converter. It should be noted that the control method of the DC hydrogen production converter provided by the embodiments of the present invention may be executed by a control device of the DC hydrogen production converter. The control device of the DC hydrogen production converter may be implemented as part or all of an electronic device through software, hardware, or a combination of software and hardware. Among them, the electronic device may be a server or a terminal. Among them, the server in the embodiments of the present application may be a single server or a server cluster composed of multiple servers. The terminal in the embodiments of the present application may be other intelligent hardware devices such as a smart phone, a personal computer, a tablet computer, a wearable device, and a smart robot. In the following method embodiments, the execution entity is taken as an example of an electronic device for description.

[0058] The following embodiments of the present application will exemplarily introduce the solution of the control method of the DC hydrogen production converter in two parts.

[0059] The first part, in combination with Figures 1 to 2 , introduces a control method for a DC hydrogen production converter provided by the embodiments of the present application, aiming to introduce the specific structure of the DC hydrogen production converter and the working principle of the DC hydrogen production converter.

[0060] The second part, in combination with Figures 3 to 12 , introduces the control method of the DC hydrogen production converter provided by the embodiments of the present application, aiming to introduce how to control the DC hydrogen production converter to provide electrical energy for the hydrogen production electrolytic cell.

[0061] Next, in combination with Figures 1 to 2 , the first part of the embodiments of the present application is introduced, that is, the specific structure of the DC hydrogen production converter and the working principle of the DC hydrogen production converter are introduced.

[0062] Figure 1 FIG. is a schematic structural diagram of a DC hydrogen production converter provided by an embodiment of the present application. As Figure 1 shown, the DC hydrogen production converter includes: a dual active bridge (DAB) branch 1 and a buck converter branch 2.

[0063] The dual active bridge branch 1 is connected in parallel with the buck converter branch 2. It can be understood that the dual active bridge branch 1 can be directly connected in parallel with the buck converter branch 2, or the dual active bridge branch can be connected in series with a filter branch, and the series circuit is connected in parallel with the buck converter branch 2. In Figure 1In it, after the dual-active-bridge branch 1 is connected in series with the filtering branch 3, it is then connected in parallel with the buck-type conversion branch 2. Here, the filtering branch 3 uses specific circuit elements to filter out high-frequency noise, harmonics, and voltage and current fluctuations in the electric energy, thereby improving the power quality and providing more stable and pure electric energy for the subsequent hydrogen production electrolyzer.

[0064] The dual-active-bridge branch and the buck-type conversion branch are used to reduce the first DC voltage to the second DC voltage, and the second DC voltage is used to support the operation of the hydrogen production electrolyzer. The electric energy output by the dual-active-bridge branch and the electric energy output by the buck-type conversion branch are complementary to reduce the fluctuation of the electric energy output by the DC hydrogen production converter.

[0065] In a possible implementation manner, the dual-active-bridge branch 1 is a DC-DC converter. The dual-active-bridge branch 1 includes two active bridges (such as full-bridge converters) and a high-frequency isolation transformer. The dual-active-bridge branch has the ability of bidirectional power transmission. During the DC hydrogen production process, the dual-active-bridge branch 1 can effectively reduce the higher first DC voltage to the second DC voltage suitable for the operation of the hydrogen production electrolyzer, providing working voltage support for the hydrogen production electrolyzer, and can also achieve energy reverse transmission under specific circumstances (such as when there is an energy storage device and energy needs to be fed back to the power supply).

[0066] In a possible implementation manner, the buck-type conversion branch 2 is a DC-DC conversion circuit topology. That is to say, the buck-type conversion branch can also reduce the higher DC input voltage to the reduced DC output voltage.

[0067] It should be noted that the specific structures and working principles of the dual-active-bridge branch 1 and the buck-type conversion branch 2 will be described in subsequent embodiments and will not be elaborated here.

[0068] In a possible implementation manner, the first DC voltage can be understood as the input DC voltage of the dual-active-bridge branch. The first DC voltage can be a renewable energy power generation device (such as the direct current generated by a solar photovoltaic panel array, the direct current output after rectification by a wind turbine), etc. The second DC voltage is the DC voltage output after being converted by the DC hydrogen production converter and is used to support the operation of the hydrogen production electrolyzer. Here, the value of the second DC voltage is lower than the value of the first DC voltage. The DC hydrogen production converter reduces the input higher voltage to the DC voltage suitable for the operation of the hydrogen production electrolyzer to ensure that the hydrogen production electrolyzer can efficiently and stably carry out the hydrogen production reaction.

[0069] In a possible implementation, in a DC hydrogen production converter, the dual active bridge branch 1 is used to reduce the first DC voltage to a second DC voltage, and the second DC voltage is used to support the operation of the hydrogen production electrolyzer. The buck conversion branch 2 is used to reduce the fluctuation of the electrical energy output by the dual active bridge branch 1. This is because, due to the operating principle of the dual active bridge branch 1 and the characteristics of the input power supply (such as the instability of renewable energy power generation), there may be a certain degree of fluctuation in the electrical energy output by the dual active bridge branch 1. The fluctuation of the electrical energy here can be manifested as the up and down fluctuation of the voltage amplitude and the irregular change of the current magnitude. Therefore, the current ripple of the buck conversion branch 2 is complementary to the current ripple of the dual active bridge branch 1 to achieve low ripple of the output current of the DC hydrogen production converter, thereby improving the stability of the DC hydrogen production converter and laying a foundation for improving the hydrogen production efficiency of the hydrogen production electrolyzer.

[0070] In this way, when the electrical energy output by the dual active bridge branch 1 fluctuates, the buck conversion branch 2 can respond quickly and adjust its own output according to the fluctuation situation. For example, when the output voltage of the dual active bridge branch 1 increases, the buck conversion branch 2 can reduce the conduction duty cycle of the switching tube to lower the output voltage, and vice versa, so as to make up for the fluctuation of the electrical energy output by the dual active bridge branch 1 and ensure stable electrical energy supply for the hydrogen production electrolyzer.

[0071] In another possible implementation, in a DC hydrogen production converter, the buck conversion branch 2 can be used to reduce the first DC voltage to a second DC voltage, and the dual active bridge branch 1 is used to make up for the fluctuation of the electrical energy output by the dual active bridge branch 1. Here, the dual active bridge branch mainly plays the role of stabilizing the output electrical energy. When the electrical energy output by the buck conversion branch 2 fluctuates, the dual active bridge branch 1 can compensate by adjusting its own energy transmission and conversion method. For example, when the output current of the buck conversion branch 2 suddenly increases and causes the voltage to drop, the dual active bridge branch 1 can increase its output current to maintain the stability of the output voltage; when the output voltage of the buck conversion branch 2 fluctuates, the dual active bridge branch 1 can adjust the internal power transmission to make the output voltage smoother, so as to make up for the fluctuation of the electrical energy output by the buck conversion branch 2.

[0072] In the embodiments of the present application, during the operation of the dual-active bridge branch and the buck conversion branch, due to the differences in their circuit structures and control methods, the fluctuation characteristics of the output voltage are also different. When the electrical energy output by the two is complementary, the peaks and valleys of their respective voltage ripples can cancel each other out to a certain extent. For example, if the output voltage of the dual-active bridge branch has a relatively high peak at a certain moment, while the output voltage of the buck conversion branch is at a relatively low level at this time, after the two are superimposed, the peak of the overall output voltage will be pulled down, effectively reducing the ripple of the output voltage, providing a more stable DC voltage for the hydrogen production electrolyzer, and being beneficial to improving the electrolysis efficiency and extending the service life of the electrolyzer electrodes. Similarly, the dual-active bridge branch and the buck conversion branch also reduce the output current fluctuation of the DC hydrogen production converter through complementary effects. In addition, in the DC hydrogen production converter, the dual-active bridge branch 1 and the buck conversion branch 2 cooperate with each other, and can flexibly adjust the working states of the dual-active bridge branch 1 and the buck conversion branch 2 to achieve optimized energy management and enhance the reliability of the DC hydrogen production converter. For example, when one of the branches fails or malfunctions, the other branch can maintain the operation of the system to a certain extent, improving the reliability and fault tolerance of the entire DC hydrogen production converter system.

[0073] As Figure 1 shown, the filtering branch 3 includes a first resistor 31 and a third capacitor 32. In the filtering branch 3, the first resistor 31 and the third capacitor 32 cooperate. Among them, the first resistor 31 can consume a part of the electrical energy, change the current and voltage distribution in the circuit, and play roles such as suppressing high-frequency signals and adjusting the circuit time constant. The third capacitor 32 can store charges and play a buffering role in the voltage change. It can allow low-frequency signals to pass through smoothly, while presenting a relatively low impedance to high-frequency signals, thereby bypassing high-frequency noise and fluctuations to the ground to achieve the filtering effect.

[0074] Exemplarily, when there are high-frequency noise and fluctuations in the electrical energy output by the dual-active bridge branch 1, the current first flows into the filtering branch 3. The filtering circuit composed of the first resistor 31 and the third capacitor 32 plays a filtering role. For high-frequency signals, the capacitive reactance of the third capacitor 32 is small, and most of the high-frequency current will be bypassed. The first resistor 31 plays a certain limiting and regulating role on the current to avoid damage to subsequent components caused by excessive current. After the filtering process, the high-frequency noise and fluctuations are effectively suppressed, and the power quality is improved. At the same time, since the series-connected filtering branch 3 and the dual-active bridge branch 1 are in parallel with the buck conversion branch 2, the two branches can jointly provide electrical energy for the hydrogen production electrolyzer. The buck conversion branch 2 can further stabilize and adjust the electrical energy output by the dual-active bridge branch 1. The dual-active bridge branch 1 and the buck conversion branch 2 cooperate with each other to provide stable and high-quality electrical energy for the hydrogen production electrolyzer, ensuring the efficient and stable operation of the hydrogen production process.

[0075] In the embodiment of the present application, considering that in the operation process of the dual-active bridge branch 1, due to the high-frequency operation of the switching devices, rich harmonics will be generated. Therefore, a filtering branch 3 connected in series with the dual-active bridge branch 1 is introduced in the DC hydrogen production converter, which can effectively suppress these harmonics, reduce the harmonic content in the output current and voltage, and provide more ideal DC electric energy for the hydrogen production electrolyzer. At the same time, there may be certain voltage and current fluctuations in the electric energy output by the dual-active bridge branch 1. The filtering branch 3 can smooth these fluctuations, make the output voltage and current more stable, reduce the voltage spikes and current mutations, and improve the stability of the electric energy output by the DC hydrogen production converter.

[0076] In Figure 1 , the dual-active bridge branch 1 includes a first capacitor 11, a first H-bridge converter 12, a first inductor 13, a high-frequency isolation transformer 14, and a second H-bridge converter 15. The first capacitor 11 is used to stabilize the input voltage of the dual-active bridge branch 1. The first inductor 13 is used to store instantaneous energy. The high-frequency isolation transformer 14 is used to achieve electrical isolation.

[0077] Wherein, the input end of the first H-bridge converter 12 is connected to both ends of the first capacitor 11; one output end of the first H-bridge converter 12 is connected to one end of the primary winding of the high-frequency isolation transformer 14 through the first inductor 13; the other end of the primary winding of the high-frequency isolation transformer 14 is connected to the other output end of the first H-bridge converter 12; the secondary winding of the high-frequency isolation transformer 14 is connected to the input end of the second H-bridge converter 15.

[0078] It can be understood that the number of H-bridge converters included in the dual-active bridge branch 1 in the DC hydrogen production converter can also be more than two, and the H-bridge converters can be connected in series or in parallel, etc. Multiple H-bridge converters can realize the functions of the first H-bridge converter 12 and the second H-bridge converter 15 in the dual-active bridge branch 1.

[0079] In a possible implementation manner, the H-bridge converter includes a plurality of fully controlled power electronic devices, such as Insulated Gate Bipolar Transistors (IGBTs). The fully controlled power electronic devices have the ability to freely control their conduction and turn-off through control signals, that is, as switching tubes, they control the on and off of the circuit.

[0080] Such as Figure 1As shown, the first H-bridge converter 12 includes four IGBTs (i.e., S1, S2, S3, S4) and four diodes (i.e., D1, D2, D3, D4). The second H-bridge converter 15 includes four IGBTs (i.e., Q1, Q2, Q3, Q4) and four diodes (i.e., M1, M2, M3, M4). For each arm in each H-bridge converter, one IGBT is connected in parallel with the corresponding diode. Specifically, the emitter of the IGBT is connected to the positive electrode of the corresponding diode, and the collector of the IGBT is connected to the negative electrode of the corresponding diode.

[0081] In the embodiment of the present application, in the dual active bridge branch 1, the first H-bridge converter 12 and the second H-bridge converter 15 cooperate with each other, enabling the dual active bridge branch 1 to achieve bidirectional power transmission. In the case of unstable renewable energy power generation, when the generated power is excessive, the energy can be transmitted from the first H-bridge converter 12 through the first inductor 13 and the high-frequency isolation transformer 14 to the second H-bridge converter 15 to supply power to the hydrogen production electrolyzer; when the generated power is insufficient, the first inductor 13 can reverse-transmit the energy to the first H-bridge converter 12 side, realizing flexible allocation of energy and improving the energy utilization efficiency. The high-frequency isolation transformer 14 electrically isolates the primary side and the secondary side of the circuit, effectively preventing electrical faults in the primary side circuit from being conducted to the secondary side, ensuring the safe operation of secondary side devices such as the hydrogen production electrolyzer. In addition, the high-frequency isolation transformer 14 can also perform voltage matching and transformation according to the turns ratio of the transformer. Therefore, by designing the turns ratio of the transformer, the input DC voltage can be converted into a DC voltage suitable for the operation of the hydrogen production electrolyzer, meeting the voltage requirements of different hydrogen production processes and enhancing the applicability of the DC hydrogen production converter.

[0082] Next, taking Figure 1 the dual active bridge branch 1 as an example, the working principle of the dual active bridge branch 1 will be described. It is assumed that the DC hydrogen production converter has been operating in a stable state. According to the forward power flow control principle, the working mode of the dual active bridge branch 1 can be divided into six modes. Figure 2 FIG. Figure 2 shows the schematic diagrams of the six working modes provided by the embodiment of the present application. As

[0083] shown, in the stage of t = t0 to t0', the working mode of the dual active bridge branch 1 is mode 1; in the stage of t = t0' to t1, the working mode of the dual active bridge branch 1 is mode 2; in the stage of t = t1 to t2, the working mode of the dual active bridge branch 1 is mode 3; in the stage of t = t2 to t2', the working mode of the dual active bridge branch 1 is mode 4; in the stage of t = t2' to t3, the working mode of the dual active bridge branch 1 is mode 5; in the stage of t = t3 to t4, the working mode of the dual active bridge branch 1 is mode 6.

[0083] The working state of the dual active bridge branch 1 in mode 1 is as Figure 2As shown, before time t0, the switching transistors S2 and S3 are conducting and the current is negative; at time t0, the switching transistors S2 and S3 turn off, and S1 and S4 conduct. Since the current is still negative, the current continues to flow through D1 and D4, and S2 and S3 are hard turned off while D1 and D4 are hard conducting. The current expression of the first inductor 13 can be expressed as:

[0084]

[0085] where, i L (t) is the current of the first inductor 13 at time t, V1 and V2 are the DC terminal voltages of the first H-bridge converter 12 and the second H-bridge converter 15 respectively, L is the inductance coefficient of the first inductor 13, and n is the turns ratio of the high-frequency isolation transformer 14.

[0086] The operating state of the dual-active-bridge branch 1 in mode 2 is as Figure 2 shown. At time t0', the inductor current changes from negative to positive. The primary-side full-bridge current switches from D1 and D4 to S1 and S4, and the secondary-side full-bridge current switches from M2, M3 to Q2, Q3. S1 and S4 are turned on with zero-voltage switching (ZVS), D1 and D4 are turned off with zero-current switching (ZCS), Q2 and Q3 are turned on with ZVS, and M2 and M3 are turned off with ZCS. The current expression of the first inductor 13 is the same as (Equation 1).

[0087] The operating state of the dual-active-bridge branch 1 in mode 3 is as Figure 2 shown. At time t1, the switching transistors Q1 and Q4 conduct, and Q2 and Q3 turn off. Since the current i L of the first inductor 13 is positive, the primary-side full-bridge state remains unchanged, and the secondary-side full-bridge current switches from Q2 and Q3 to M1 and M4. Q2 and Q3 are hard turned off, and M1 and M4 are hard conducting. The current expression of the first inductor 13 can be expressed as:

[0088]

[0089] The operating state of the dual-active-bridge branch 1 in mode 4 is as Figure 2 shown. At time t = t2, the switching transistors S2 and S3 conduct, and S1 and S4 turn off. Since the current i L of the first inductor 13 is positive, the primary-side full-bridge current switches from S1 and S4 to D2 and D3, and the secondary-side full-bridge state remains unchanged. S1 and S4 are hard turned off, and D2 and D3 are hard conducting. The current expression of the first inductor 13 can be expressed as:

[0090]

[0091] The operating state of the dual-active bridge branch 1 in Mode 5 is as follows Figure 2 As shown, at the moment of t = t2’, the current i of the first inductor 13 L changes from positive to negative. The full-bridge current on the primary side switches from D2 and D3 to S2 and S3, and the full-bridge current on the secondary side switches from M1 and M4 to Q1 and Q4. S2 and S3 are turned on with zero voltage switching (ZVS), D2 and D3 are turned off with zero current switching (ZCS), Q1 and Q4 are turned on with ZVS, and M1 and M4 are turned off with ZCS. The current expression of the first inductor 13 is the same as (Formula Three).

[0092] The operating state of the dual-active bridge branch 1 in Mode 6 is as follows Figure 2 As shown, at the moment of t = t3, the switching transistors Q2 and Q3 are turned on, and Q1 and Q4 are turned off. Since the current i of the first inductor 13 L is negative, the state of the full-bridge on the primary side remains unchanged, and the full-bridge current on the secondary side switches from Q1 and Q4 to M2 and M3. Q1 and Q4 are turned off hard, and M2 and M3 are turned on hard. The current expression of the first inductor 13 can be expressed as:

[0093]

[0094] In the above six operating modes, all the switching transistors of the dual-active bridge branch 1 operate in the zero voltage switching (ZVS) turn-on state and the hard turn-off state, and all the diodes operate in the hard turn-on and ZCS turn-off states.

[0095] In Figure 1 , the buck conversion branch 2 includes a first insulated gate bipolar transistor 21, a second insulated gate bipolar transistor 22, a first diode 23, a second diode 24, a second inductor 25, and a second capacitor 26. The second inductor 25 is used to smooth the current, store and transfer energy, and prevent current fluctuations. The second capacitor 26 is used to smooth the output voltage, filter out high-frequency noise and ripple, and ensure the stability of the output.

[0096] Among them, the emitter of the insulated gate bipolar transistor is connected to the positive pole of the diode, and the collector of the insulated gate bipolar transistor is connected to the negative pole of the diode; the emitter of the first insulated gate bipolar transistor 21 is respectively connected to the collector of the second insulated gate bipolar transistor 22 and one end of the second inductor 25; the other end of the second inductor 25 is connected to one end of the second capacitor 26; the other end of the second capacitor 26 is connected to the emitter of the second insulated gate bipolar transistor 22; the collectors of the first insulated gate bipolar transistor 21 and the emitter of the second insulated gate bipolar transistor 22 serve as the input end of the buck conversion branch 2; both ends of the second capacitor 26 serve as the output end of the buck conversion branch 2.

[0097] When the first insulated gate bipolar transistor 21 is closed, the power supply starts to charge the second inductor 25 and the second capacitor 26, and supplies power to the load R. At this time, the second inductor 25 takes away a part of the power supply voltage, so the voltage of the load R is lower than the power supply voltage. During this period, the inductor voltage rises and the load voltage rises. When the first insulated gate bipolar transistor 21 is turned off, the electrical energy stored in the second inductor 25 is released, and the second inductor 25 serves as a new power supply to supply power to the load, and is transmitted to the output through the second diode 24 circuit. The inductor voltage decreases and the load voltage decreases. Therefore, the buck conversion branch 2 can control the on-time of the switching tube, so that the switch is periodically closed and opened, and the load voltage can change periodically, and finally decrease near the target voltage.

[0098] In the embodiment of the present application, in the buck conversion branch 2, the insulated gate bipolar transistor has the characteristics of fast switching speed and high control precision. By controlling the conduction and cut-off of the insulated gate bipolar transistor, the output voltage and current can be conveniently adjusted to adapt to different load requirements and working conditions. This flexible control method enables the buck conversion branch 2 to operate efficiently under different working conditions, improving the adaptability and efficiency of the entire DC hydrogen production converter.

[0099] The above is the first part of the embodiment of the present application. The following will be combined with Figures 3 to 12 to introduce the second part of the embodiment of the present application, that is, the specific implementation method of controlling the DC hydrogen production converter.

[0100] In the embodiment of the present application, based on the circuit structure of the DC hydrogen production converter in the first part, a mathematical model of the DC hydrogen production converter is established, and its control system is established based on the mathematical model, and the functions of each part of the control system are analyzed, specifically including:

[0101] According to the circuit schematic diagram of the dual active bridge branch 1, the current i L1 (t) of the first inductor 13 can be expressed as:

[0102]

[0103] Among them, V H1 is the AC output voltage of the first H-bridge converter 12, and V H2 is the voltage of the AC output of the second H-bridge converter 15 after being folded to the primary side of the transformer.

[0104] The transmission power of the dual active bridge branch 1 is:

[0105]

[0106] Among them, P is the transmission power of the dual active bridge branch 1, and T hs is half of the switching period.

[0107] (1) When 0 ≤ t ≤ DT hs (where D is the phase shift ratio), v H1 = v1, v H2 = -nv2

[0108]

[0109] where v1 and v2 are the DC terminal voltages of the first H-bridge converter 12 and the second H-bridge converter 15 respectively, and i L1 '(t) is the current of the first inductor 13 at time t in stage (1) (i.e., 0 ≤ t ≤ DT hs ).

[0110] Integrating gives:

[0111]

[0112] where C1 is a constant.

[0113] (2) When DT hs ≤ t ≤ T hs , v H1 = v1, v H2 = nv2,

[0114]

[0115] where i L1 ”(t) is the current of the first inductor 13 at time t in stage (2) (i.e., DT hs ≤ t ≤ T hs ).

[0116] Integrating gives the inductor current:

[0117]

[0118] where C2 is a constant.

[0119] To determine the constants C1 and C2, two boundary conditions are needed.

[0120] (1) Boundary condition 1: t = DT hs The voltage v H2 changes from -nv2 to nv2, but the inductor current does not change suddenly at this time. Substituting t = DT hs into the above two inductor current values gives them equal.

[0121] (2) Boundary condition 2: The volt-second conservation law under steady-state conditions. In a complete switching period, the sum of the currents flowing through the voltage is zero, i.e., i L (T hs ) = -i L (0)

[0122] In summary, it can be obtained that:

[0123]

[0124] After simplification, constants C1 and C2 can be obtained, and

[0125]

[0126] Substituting Equation (12) into Equation (6) gives

[0127]

[0128] where is the switching frequency, n is the turns ratio of the high-frequency isolation transformer 14, D is the phase shift ratio of half a switching period. Substituting f into Equation (13) gives the power transfer formula:

[0129]

[0130] It can be seen from Equation (14) that the magnitude of the phase shift ratio D can be controlled to control the magnitude P of the power transferred by the dual-active-bridge branch 1.

[0131] Figure 3 is a schematic diagram of the power transfer characteristic of the dual-active-bridge branch 1. Figure 3 The curve power of the power transferred by the shown dual-active-bridge branch 1 is the per-unit value of the power, and the base value of the power is taken as where f s is the switching frequency of the switching device (such as IGBT) in the dual-active-bridge branch 1. From Figure 3 the following rules can be obtained: (1) The power transferred between the two full bridges of the dual-active-bridge branch 1 has a trigonometric function relationship with the phase shift ratio D and is symmetric about D = 0.5. (2) When D < 0.5, the transferred power increases with the increase of the phase shift ratio D. When D > 0.5, the transferred power decreases with the increase of the phase shift ratio D.

[0132] The buck conversion branch 2 can be divided into a continuous conduction mode (CCM), a boundary conduction mode (BCM), and a discontinuous conduction mode (DCM) according to the working state. In the present invention, the buck conversion branch 2 needs to operate in the CCM mode. In the CCM mode, the current of the second inductor 25 does not drop to zero during the entire switching cycle. That is to say, during the conduction period of the switching transistor, the current of the second inductor 25 linearly increases; during the off period of the switching transistor, the current of the second inductor 25 linearly decreases but always remains greater than zero. This means that the second inductor 25 is always in a state of storing and releasing energy, and there is no moment when the energy is completely released. In this mode, the buck conversion branch 2 has a good dynamic response to the circuit and can quickly adapt to changes in the load.

[0133] When the first insulated gate bipolar transistor 21 conducts, the input voltage supplies power to the second inductor 25, and the second inductor 25 enters the energy storage state. The conduction time of the first insulated gate bipolar transistor 21 is t on = D’T, where D’ is the duty cycle and T is the switching cycle of the entire converter.

[0134] The voltage across the second inductor 25 is:

[0135]

[0136] Where, V L is the voltage across the second inductor 25, and V in , V out2 are the input voltage and output voltage of the second inductor 25 respectively.

[0137] During the conduction period of the first insulated gate bipolar transistor 21, the change in the current on the second inductor 25:

[0138]

[0139] When the first insulated gate bipolar transistor 21 is turned off, the second diode 24 is in the conducting state. The second inductor 25 is in the discharging state. Ignoring the voltage drop across the second diode 24, one end voltage of the second inductor 25 is 0 at this time, and the other end voltage is V out2 . The inductor current linearly decreases, and the voltage across the second inductor 25 is:

[0140]

[0141] During the off period of the first insulated gate bipolar transistor 21, the change in the current flowing through the second inductor 25 is:

[0142]

[0143] According to the "volt - second balance theorem", ΔI can be obtained L+ = ΔI L- , substituting into Formula XVI and Formula XVIII, the following relationship can be obtained:

[0144] V out2 = D'V in (Formula XIX)

[0145] From the above formula, it can be known that the output voltage V out2 after passing through the buck - type conversion branch, the duty cycle D’ and the input voltage V in affect the value of V out2 , and since D’ = t on / T, so 0 < D’ < 1, it can be concluded that the output voltage V out2 is less than the input voltage V in .

[0146] Exemplarily, Table 1 shows the parameter settings in the DC hydrogen production converter.

[0147] Table 1 Parameter Settings

[0148]

[0149] Based on the above analysis, the embodiment of the present application provides a control method for a DC hydrogen production converter. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer - executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0150] In this embodiment, a control method for a DC hydrogen production converter is provided, which can be used for the above - mentioned DC hydrogen production converter Figure 4 is a flowchart of a control method for a DC hydrogen production converter according to an embodiment of the present invention. Through this control method, the DC hydrogen production converter in Figure 1 is controlled. As shown in Figure 4 , this process includes the following S101 - S103:

[0151] S101: Obtain the first current.

[0152] Among them, the first current is the output current of the buck - type conversion branch 2 in the DC hydrogen production converter.

[0153] Exemplarily, the first current can be measured by a current sensor, such as a Hall current sensor. Based on the Hall effect, the Hall current sensor can convert the measured current into a voltage signal, and the corresponding current value can be obtained by measuring this voltage signal.

[0154] S102: Determine the reference current corresponding to the first current.

[0155] Among them, the reference current corresponding to the first current is obtained based on the second current and the reference current corresponding to the second current; the second current is the output current of the dual-active-bridge branch 1 in the DC hydrogen production converter.

[0156] In a possible implementation, the reference current corresponding to the second current can be understood as a preset reference current value of the second current, which is used to compare with the actual second current. During the process of controlling the DC hydrogen production converter, by comparing the second current with its corresponding reference current, it is judged whether the output current of the dual-active-bridge branch 1 meets the requirements, so as to perform corresponding adjustment control. Among them, the setting of the reference current is usually determined according to factors such as the requirements of the hydrogen production process and the characteristics of the electrolyzer. For example, according to parameters such as the rated current of the electrolyzer and the hydrogen production output requirements, a suitable reference current value is calculated.

[0157] In a possible implementation, the reference current corresponding to the first current is used to control and adjust the first current. For example, in the case where there is a deviation between the second current and the reference current corresponding to the second current, the reference current corresponding to the first current is set to control the first current, so as to make up for the fluctuation of the second current, that is, to dynamically adjust the output of the buck conversion branch 2 according to the working conditions of the dual-active-bridge branch 1.

[0158] S103: Control the buck conversion branch based on the first current and the reference current corresponding to the first current.

[0159] In a possible implementation, based on the first current and the reference current corresponding to the first current, a control signal is generated, and this control signal controls the on and off times of the switching tubes in the buck conversion branch 2.

[0160] Optionally, in the above S103, the buck conversion branch 2 is controlled based on the first current, the reference current corresponding to the first current, and a proportional-integral controller.

[0161] Exemplarily, in a proportional-integral regulator, the proportional link generates a control action proportionally according to the error between the current first current and the reference current corresponding to the first current. For example, if the first current is less than the reference current corresponding to the first current, the proportional link will increase the control signal, causing the output current of the buck conversion branch 2 to increase; otherwise, the control signal will be decreased. The integral link integrates the error between the first current and the reference current corresponding to the first current. As time accumulates, the integral term will gradually increase. Even if the error is very small, the integral action will continuously increase the control signal until the steady-state error is eliminated and the first current is precisely equal to the reference current. In the proportional-integral regulator, by continuously and real-time measuring the first current, comparing it with the reference current corresponding to the first current, and calculating the error therebetween (i.e., the difference between the first current and the reference current corresponding to the first current), the control signal is continuously adjusted so that the first current gradually stabilizes near the reference current, achieving precise control of the output current of the buck conversion branch 2.

[0162] It can be understood that in the embodiments of the present application, the buck conversion branch 2 is controlled by constant current control.

[0163] Through the control method of the DC hydrogen production converter provided in this embodiment, in the DC hydrogen production converter, the dual active bridge branch 1 and the buck conversion branch 2 jointly supply power to the hydrogen production electrolytic cell. Determining the reference current of the buck conversion branch 2 with reference to the output current of the dual active bridge branch 1 helps to suppress the fluctuation of the first current, can effectively reduce the ripple of the output current of the DC hydrogen production converter, thereby ensuring a stable output current, reducing the impact on the electrolytic cell electrodes, improving the electrolysis efficiency and the electrode life, and further enhancing the stability and reliability of the entire hydrogen production process.

[0164] In some embodiments, in the above S102, the reference current corresponding to the first current is determined in the following manner:

[0165] First, determine the deviation of the second current.

[0166] Wherein, the deviation of the second current is the difference between the reference current corresponding to the second current and the second current.

[0167] Then, use the difference between the initial reference current corresponding to the first current and the deviation as the reference current corresponding to the first current.

[0168] In the embodiments of the present application, considering the deviation of the second current when determining the reference current corresponding to the first current is equivalent to introducing a feedback correction mechanism. For the buck conversion branch 2, the accuracy of its output current is crucial for the stable operation of the hydrogen production electrolyzer. By continuously correcting the reference current according to the second current deviation, the error between the first current and the ideal value in the steady state can be effectively reduced. This method of adjusting the reference current based on the deviation can continuously correct this deviation, keeping the first current within a high-precision range all the time, providing a stable and accurate current supply for the hydrogen production electrolyzer, and improving the hydrogen production efficiency and quality.

[0169] Figure 5 FIG. is a schematic diagram of the control of a DC hydrogen production converter according to an embodiment of the present application. In Figure 5 , the constant current control of the buck conversion branch 2 uses the dynamic difference between the initial reference current of the buck conversion branch (i.e., I Buckref ) and the dynamic error value of the dual active bridge branch 1 (i.e., the difference between I DAB and I DABref ) as the control reference value, which forms a control deviation with the actual current value of the buck conversion branch 2 (i.e., I Buck ). Through a proportional-integral regulator, the current of the controlled object (i.e., the buck conversion branch 2) is accurately controlled, so that the current of the dual active bridge branch 1 and the current of the buck conversion branch 2 are complementary, thereby reducing the fluctuation of the output electric energy of the DC hydrogen production converter and improving the stability of the hydrogen production circuit.

[0170] In some embodiments, there is a phase difference between the drive pulses of the switching tubes in the first H-bridge converter 12 and the corresponding switching tubes in the second H-bridge converter 15.

[0171] The method provided by the embodiments of the present application further includes:

[0172] Using a single phase shift (SPS) control algorithm, by adjusting the phase difference, the electric energy output by the dual active bridge branch 1 is controlled.

[0173] Exemplarily, in SPS control, the trigger drive pulses of the switching tubes on the diagonals in each full-bridge circuit are the same, and the trigger drive pulses of the switching tubes on the same bridge arm are 180° complementary, generating high-frequency square wave voltages V H1 and V H2 with a duty cycle of 50% on the primary and secondary sides of the transformer respectively; there is a phase difference between the drive pulses of the corresponding switching tubes (such as S1 and Q1) of the first H-bridge converter 12 and the second H-bridge converter 15. By controlling two defined phase shift angles D (or phase shift times DThs), where Ths is half of the switching period.

[0174] In the embodiments of the present application, the single-phase-shift control algorithm can adjust the phase difference in real time according to the load change and input voltage fluctuation, so as to stabilize the output voltage and current of the dual-active-bridge branch 1. The stable voltage and current output helps to maintain the stability of the chemical reaction in the electrolyzer, improve the hydrogen production efficiency, reduce the loss of the electrodes, and extend the service life of the electrolyzer. For example, when the load suddenly increases, the single-phase-shift control algorithm can quickly adjust the phase difference, increase the power output, and ensure the stability of the output voltage and current.

[0175] Next, the advantages and disadvantages between the DC hydrogen production converter provided in the embodiments of the present application and the hydrogen production converter in the related art are compared through simulation. In the embodiments of the present application, a hydrogen production converter with a capacity of 12 MW is designed. In the hydrogen production converter of the related art, the theoretical value of the output voltage is 1200 V, and the theoretical value of the output current is 10000 A; in the DC hydrogen production converter provided in the embodiments of the present application, the power of the dual-active-bridge branch (i.e., the DAB branch) is 10 MW, the theoretical value of the output voltage is 1200 V, and the theoretical value of the output current is 8333.3 A. The power of the buck-type conversion branch (i.e., the Buck branch) is 2 MW, the theoretical value of the output voltage is 1200 V, and the theoretical value of the output current is 1666.7 A.

[0176] In Matlab / Simulink, a simulation model of the DC hydrogen production converter provided in the embodiments of the present application and a simulation model of the hydrogen production converter in the related art are built. Figure 6 、 Figure 7 They are respectively the output current waveform diagram and output voltage waveform diagram of the dual-active-bridge unit hydrogen production converter in the related art (also called the traditional DAB). As Figure 6 、 Figure 7 shown, the average value of the output current of the dual-active-bridge unit hydrogen production converter in the related art is 10000 A, the peak-to-peak value of the output current is 10600 A, the current ripple ratio is 12%, the average value of the output DC voltage is 1200 V, the peak-to-peak value of the output voltage is 1270 V, and the voltage ripple ratio is 11.7%. The relatively high current ripple of the dual-active-bridge unit hydrogen production converter in the related art will cause the electrolyzer to heat up, thereby reducing the efficiency and purity of electrolytic hydrogen production, and greatly reducing the economy of electrolytic hydrogen production.

[0177] Figure 8 and Figure 9 They are respectively the output current waveform diagram and output voltage waveform diagram of the dual-active-bridge branch (also called the new hydrogen production converter DAB branch) in the DC hydrogen production converter provided in the embodiments of the present application. Figure 10 and Figure 11 They are respectively the output current waveform diagram and output voltage waveform diagram of the buck-type conversion branch (also called the new hydrogen production converter Buck branch) in the DC hydrogen production converter provided in the embodiments of the present application. Figure 12This is the waveform diagram of the total output current of the DC hydrogen production converter (also known as the new hydrogen production converter) provided by the embodiments of the present application.

[0178] In the DC hydrogen production converter provided by the embodiments of the present application, the average value of the output DC current of the dual active bridge branch is 8000A, the peak-to-peak value of the output current is 10500A, and the current ripple ratio is 62.5%; the average value of the output DC voltage is 1190V, the peak-to-peak value of the output voltage is 1240V, and the voltage ripple ratio is 8.4%. In the DC hydrogen production converter provided by the embodiments of the present application, the average value of the output DC current of the buck conversion branch is 1675A, the peak-to-peak value of the output current is 1750A, and the current ripple ratio is 8.9%; the average value of the output DC voltage is 1190V, the peak-to-peak value of the output voltage is 1240V, and the voltage ripple ratio is 8.4%. The average value of the total output current of the DC hydrogen production converter is 9850A, the peak-to-peak value of the output current is 10200A, and the current ripple ratio is 7.1%.

[0179] From the above Figures 6 to 12 it can be seen that, compared with the hydrogen production converter in the related art, the DC hydrogen production converter provided by the embodiments of the present application has lower DC ripple in the total output current and is more suitable for the electrolytic hydrogen production scenario. The DC hydrogen production converter provided by the embodiments of the present application can not only improve the efficiency and purity of the hydrogen production power supply, ensure the safe and stable operation of the hydrogen production electrolytic cell, but also the larger output current can increase the hydrogen production amount per unit time and increase the economic benefits.

[0180] The above mainly introduces the solution provided by the embodiments of the present application from the perspective of the method.

[0181] In the embodiments of the present application, a control device for a DC hydrogen production converter is also provided. This device is used to implement the above embodiments and preferred implementation manners, and those that have been described will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0182] The present embodiment provides a control device for a DC hydrogen production converter, as Figure 13 shown, including:

[0183] An acquisition module 1301, configured to acquire a first current; the first current is the output current of the buck conversion branch in the DC hydrogen production converter;

[0184] A determination module 1302, configured to determine a reference current corresponding to the first current; the reference current corresponding to the first current is obtained based on a second current and a reference current corresponding to the second current; the second current is the output current of the dual active bridge branch in the DC hydrogen production converter;

[0185] A control module 1303 is configured to control the buck conversion branch based on the first current and the reference current corresponding to the first current.

[0186] With the device provided in this embodiment, in a DC hydrogen production converter, the dual active bridge branch and the buck conversion branch jointly supply power to the hydrogen production electrolyzer. Determining the reference current of the buck conversion branch with reference to the output current of the dual active bridge branch helps to suppress the fluctuation of the first current, can effectively reduce the ripple of the output current of the DC hydrogen production converter, thereby ensuring a stable output current, reducing the impact on the electrolyzer electrodes, improving the electrolysis efficiency and electrode life, and further enhancing the stability and reliability of the entire hydrogen production process.

[0187] In some optional embodiments, the determination module 1302 includes:

[0188] A first determination sub-module is configured to determine the deviation of the second current; the deviation of the second current is the difference between the reference current corresponding to the second current and the second current;

[0189] A second determination sub-module is configured to use the difference between the initial reference current corresponding to the first current and the deviation as the reference current corresponding to the first current.

[0190] In some optional embodiments, the control module 1303 is specifically configured to control the buck conversion branch based on the first current, the reference current corresponding to the first current, and a proportional-integral regulator.

[0191] In some optional embodiments, the dual active bridge branch includes a first capacitor, a first H-bridge converter, a first inductor, a high-frequency isolation transformer, and a second H-bridge converter; the input terminals of the first H-bridge converter are connected to both ends of the first capacitor; one output terminal of the first H-bridge converter is connected to one end of the primary winding of the high-frequency isolation transformer through the first inductor; the other end of the primary winding of the high-frequency isolation transformer is connected to the other output terminal of the first H-bridge converter; the secondary winding of the high-frequency isolation transformer is connected to the input terminal of the second H-bridge converter; there is a phase difference between the drive pulses of the switching tubes in the first H-bridge converter and the corresponding switching tubes in the second H-bridge converter.

[0192] The device is further configured to use a single-phase shift control algorithm to control the electric energy output by the dual active bridge branch by adjusting the phase difference.

[0193] The further function descriptions of the above-mentioned various modules and units are the same as those in the corresponding above embodiments, and will not be elaborated here.

[0194] The control device of the DC hydrogen production converter in this embodiment is presented in the form of functional units. Here, the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and a memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0195] An embodiment of the present invention further provides a computer device having the above Figure 13 control device of the DC hydrogen production converter shown.

[0196] Please refer to Figure 14 , Figure 14 which is a schematic structural diagram of a computer device provided by an optional embodiment of the present invention. As Figure 14 shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including a high-speed interface and a low-speed interface. Each component communicates with each other using different buses and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed within the computer device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (such as an array of servers, a set of blade servers, or a multi-processor system). Figure 14 In

[0197] Figure, a single processor 10 is taken as an example.

[0198] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0199] The memory 20 may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the computer device and the like. In addition, the memory 20 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 may optionally include a memory remotely provided with respect to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0200] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, a hard disk, or a solid-state drive; the memory 20 may further include a combination of the above types of memory.

[0201] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0202] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium may further include a combination of the above types of memory. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiment is implemented.

[0203] A part of the present invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the present invention through the operations of the computer. Those skilled in the art should understand that the forms in which computer program instructions exist in a computer-readable medium include but are not limited to source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include but are not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to the computer.

[0204] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A DC hydrogen production converter, characterized in that: The DC hydrogen production converter includes: a dual active bridge branch and a step-down conversion branch; the dual active bridge branch is connected in parallel with the step-down conversion branch; the dual active bridge branch and the step-down conversion branch are used to reduce a first DC voltage to a second DC voltage, and the second DC voltage is used to support the operation of the hydrogen production electrolyzer; the electric energy output by the dual active bridge branch and the electric energy output by the step-down conversion branch are complementary to each other, so as to reduce the electric energy fluctuation output by the DC hydrogen production converter.

2. The DC hydrogen production converter according to claim 1, characterized in that: The dual active bridge branch is used to reduce the first DC voltage to the second DC voltage; The step-down conversion branch is used to reduce the fluctuation of the electric energy output by the dual active bridge branch.

3. The DC hydrogen production converter according to claim 1 or 2, characterized in that: The DC hydrogen production converter also includes a filter branch; the filter branch is connected in series with the dual active bridge branch, and the series-connected branch is connected in parallel with the step-down conversion branch.

4. The DC hydrogen production converter according to claim 1 or 2, characterized in that: The dual active bridge branch includes a first capacitor, a first H-bridge converter, a first inductor, a high-frequency isolation transformer and a second H-bridge converter; the input end of the first H-bridge converter is connected to the two ends of the first capacitor; an output end of the first H-bridge converter is connected to one end of the primary winding of the high-frequency isolation transformer through the first inductor; the other end of the primary winding of the high-frequency isolation transformer is connected to the other output end of the first H-bridge converter; the secondary winding of the high-frequency isolation transformer is connected to the input end of the second H-bridge converter.

5. The DC hydrogen production converter according to claim 4, characterized in that: The step-down conversion branch includes a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a first diode, a second diode, a second inductor and a second capacitor; the emitter of the insulated gate bipolar transistor is connected to the positive electrode of the diode, and the collector of the insulated gate bipolar transistor is connected to the negative electrode of the diode; the emitter of the first insulated gate bipolar transistor is respectively connected to the collector of the second insulated gate bipolar transistor and one end of the second inductor; the other end of the second inductor is connected to one end of the second capacitor; the other end of the second capacitor is connected to the emitter of the second insulated gate bipolar transistor; the collector of the first insulated gate bipolar transistor and the emitter of the second insulated gate bipolar transistor serve as the input end of the step-down conversion branch; and the two ends of the second capacitor serve as the output ends of the step-down conversion branch.

6. A control method for a direct current hydrogen production converter, characterized in that: For the DC hydrogen production converter according to any one of claims 1 to 5, the method comprises: Obtaining a first current; the first current is an output current of a step-down conversion branch in a DC hydrogen production converter; Determine a reference current corresponding to the first current; the reference current corresponding to the first current is obtained based on the second current and the reference current corresponding to the second current; the second current is the output current of the dual active bridge branch in the DC hydrogen production converter; The buck conversion branch is controlled based on the first current and a reference current corresponding to the first current.

7. The method according to claim 6, characterized in that The determining a reference current corresponding to the first current includes: Determining a deviation of the second current; the deviation of the second current being a difference between a reference current corresponding to the second current and the second current; The difference between an initial reference current corresponding to the first current and the deviation is used as a reference current corresponding to the first current.

8. The method according to claim 6 or 7, characterized in that: The controlling the step-down conversion branch based on the first current and a reference current corresponding to the first current includes: The buck conversion branch is controlled based on the first current, a reference current corresponding to the first current, and a proportional-integral regulator.

9. The method according to claim 6 or 7, characterized in that: The dual active bridge branch includes a first capacitor, a first H-bridge converter, a first inductor, a high-frequency isolation transformer and a second H-bridge converter; the input end of the first H-bridge converter is connected to the two ends of the first capacitor; an output end of the first H-bridge converter is connected to one end of the primary winding of the high-frequency isolation transformer through the first inductor; the other end of the primary winding of the high-frequency isolation transformer is connected to the other output end of the first H-bridge converter; the secondary winding of the high-frequency isolation transformer is connected to the input end of the second H-bridge converter; there is a phase difference between the driving pulse of the switch tube in the first H-bridge converter and the driving pulse of the corresponding switch tube in the second H-bridge converter; The method further comprises: The single phase shift control algorithm is used to control the electric energy output by the dual active bridge branches by adjusting the phase difference.

10. A control device for a direct current hydrogen production converter, characterized in that: Used in the direct current hydrogen production converter according to any one of claims 1 to 5, the device comprising: An acquisition module, used for acquiring a first current; the first current is an output current of a step-down conversion branch in a DC hydrogen production converter; A determination module, used to determine a reference current corresponding to the first current; the reference current corresponding to the first current is obtained based on the second current and the reference current corresponding to the second current; the second current is the output current of the dual active bridge branch in the DC hydrogen production converter; A control module is used to control the buck conversion branch based on the first current and a reference current corresponding to the first current.

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