Hydrogen production power supply circuit based on first-level high-frequency conversion

Abstract

The present invention provides a hydrogen production power supply circuit based on a first-stage high-frequency conversion, which relates to the technical field of hydrogen production power supplies. The circuit includes a pre-stage adjustable transformer and three independent AC / DC conversion modules; the pre-stage adjustable transformer includes a primary winding and a secondary winding, and the secondary winding includes three independent side windings; each AC / DC conversion module includes an AC / DC rectifier, a DC / DC step-down transformer and a capacitor. The transformer + three independent AC / DC rectifiers and DC / DC step-down transformers proposed in the embodiments of the present invention use high-frequency power electronic converters to replace the original thyristor rectification scheme, which can reduce the ripple of the output current, suppress the interference of harmonic currents, facilitate the control of various factors during the electrolysis production process, ensure the stability of the current density, thereby realizing the improvement of the electrolysis efficiency and increasing the output of electrolytic products.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production power supplies, and particularly to a hydrogen production power supply circuit based on a first-stage high-frequency conversion. Background Art

[0002] The production and utilization of hydrogen energy is a major trend in the development of the world's energy. Hydrogen production systems using renewable energy power such as wind power and photovoltaic power generation are the future development direction of hydrogen production. However, the electric energy generated by new energy cannot be directly applied to electrolytic hydrogen production, and a hydrogen production power supply is required for conversion in the middle. As the core of a new energy hydrogen production system, the hydrogen production power supply needs to have the capabilities of low voltage and large current, long-term stable operation, and low output current ripple. When using alternating current generated by renewable energy sources such as wind turbines to supply power to a hydrogen production device, an AC / DC converter is required to perform AC-DC conversion to provide the direct current required by the electrolyzer.

[0003] Currently, the converter most widely used in industrial hydrogen production is the 12-pulse thyristor full-bridge rectifier. As Figure 1 shown, the primary side of the transformer uses a delta single-winding input, and the secondary side uses a delta / star double-winding output, thereby achieving a 30° phase difference in the three-phase input voltage. This converter is realized by connecting a balance reactor in parallel and can be applied to high-power hydrogen production. The grid-side current of this topology mainly consists of 12k±1 harmonics, and the output current mainly contains 12k harmonics. There are still problems such as low power factor, large harmonic current on the AC side of the power grid, and large ripple current on the DC side, which reduces the electrolytic hydrogen production efficiency. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In view of the deficiencies of the prior art, the present invention provides a hydrogen production power supply circuit based on a first-stage high-frequency conversion, which solves the technical problems such as low power factor, large harmonic current on the AC side of the power grid, and large ripple current on the DC side existing in the existing 12-pulse thyristor rectification.

[0006] (II) Technical Solutions

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] The present invention provides a hydrogen production power supply circuit based on a first-stage high-frequency conversion, including a pre-stage adjustable transformer and three independent AC / DC conversion modules; the pre-stage adjustable transformer includes a primary winding and a secondary winding, the primary winding is connected in a delta shape, and the secondary winding includes three independent side windings; each AC / DC conversion module includes an AC / DC rectifier, a DC / DC step-down converter, and a capacitor.

[0009] Among them, the connection method in each AC / DC conversion module includes:

[0010] The first end of the side winding is connected to the first end of the AC / DC rectifier;

[0011] The second end of the side winding is connected to the third end of the AC / DC rectifier;

[0012] The second end of the AC / DC rectifier is connected to the first input end of the DC / DC step-down converter;

[0013] The fourth end of the AC / DC rectifier is connected to the second input end of the DC / DC step-down converter; A capacitor is connected between the AC / DC rectifier and the DC / DC step-down converter;

[0014] The first output ends of the three DC / DC step-down converters are connected in parallel and then connected to the first end of the DC load;

[0015] The second output ends of the three DC / DC step-down converters are connected in parallel and then connected to the second end of the DC load.

[0016] Preferably, the capacitors in the three independent AC / DC conversion modules are all high-frequency capacitors; There are several switching tubes in the three AC / DC conversion modules. By controlling the turn-off and conduction of the switching tubes, the AC / DC rectifier and the DC / DC step-down converter in each AC / DC conversion module adopt a two-stage structure of a front stage and a rear stage, and always one stage works in the power frequency mode at the same time during the working process.

[0017] Preferably, the three AC / DC rectifiers all include first, second, third, and fourth switching tubes;

[0018] Among them, the second end of the first switching tube is connected to the first end of the second switching tube, and their common end is connected to the first end of the AC / DC rectifier;

[0019] The first end of the first switching tube is connected to the first end of the third switching tube, serving as the second end of the AC / DC rectifier;

[0020] The second end of the second switching tube is connected to the second end of the fourth switching tube, serving as the fourth end of the AC / DC rectifier;

[0021] The first end of the fourth switching tube is connected to the second end of the third switching tube, serving as the third end of the AC / DC rectifier;

[0022] The third ends of the first, second, third, and fourth switching tubes are all connected to the control end for the turn-off and conduction of the switching tubes.

[0023] Preferably, each of the three AC / DC rectifiers further includes an inductor. The first end of the inductor is connected to the first end of the AC / DC rectifier, and the second end of the inductor is connected to the common end of the first switch and the second switch.

[0024] Preferably, each of the three DC / DC step-down converters includes a fifth switch, a sixth switch, an output inductor, and a filter capacitor;

[0025] Wherein,

[0026] The first end of the fifth switch is the first input end of the DC / DC step-down converter;

[0027] The second end of the fifth switch is connected to the first end of the sixth switch;

[0028] The connection end of the fifth switch and the sixth switch is connected to the output inductor and then serves as the first output end of the DC / DC step-down converter;

[0029] The second end of the sixth switch is connected between the second input end and the second output end of the DC / DC step-down converter;

[0030] The filter capacitor is connected to the first output end and the second output end of the DC / DC step-down converter;

[0031] The third ends of the fifth and sixth switches are both connected to the control end for turning off and on the switches.

[0032] Preferably, different DC electrolysis voltages required for different electrolysis stages are obtained by adjusting the SPWM modulation ratio of the AC / DC rectifier and the duty cycle of the DC / DC step-down converter to adapt to loads of different voltage levels.

[0033] Preferably, the switch includes a MOSFET.

[0034] Preferably, the capacitor is a high-frequency thin-film capacitor.

[0035] Preferably, each of the three AC / DC rectifiers includes an inductor, a first, a second, a third, and a fourth switch; each of the three DC / DC step-down converters includes a fifth switch, a sixth switch, an output inductor, and a filter capacitor;

[0036] Wherein, the second end of the first switch is connected to the first end of the second switch, and their common end is connected to the inductor and serves as the first end of the AC / DC rectifier;

[0037] The first end of the first switch is connected to the first end of the third switch and serves as the second end of the AC / DC rectifier; the second end of the AC / DC rectifier is connected to the first end of the fifth switch;

[0038] The second terminal of the second switching transistor is connected to the second terminal of the fourth switching transistor, serving as the third terminal of the AC / DC rectifier;

[0039] One terminal of the fourth switching transistor is connected to the second terminal of the third switching transistor, serving as the fourth terminal of the AC / DC rectifier; the fourth terminal of the AC / DC rectifier is connected to the second terminal of the sixth switching transistor;

[0040] The second terminal of the fifth switching transistor is connected to the first terminal of the sixth switching transistor; the connection terminal of the fifth switching transistor and the sixth switching transistor is connected to an output inductor and then serves as the first output terminal of the DC / DC step-down converter;

[0041] The fourth terminal of the AC / DC rectifier and the common terminal of the sixth switching transistor are connected to the second output terminal of the DC / DC step-down converter;

[0042] The filter capacitor is connected between the first output terminal and the second output terminal of the DC / DC step-down converter;

[0043] The capacitor in each AC / DC conversion module is a bus capacitor, and both ends of the bus capacitor are respectively connected to the second terminal and the third terminal of the AC / DC rectifier;

[0044] The third terminals of the first, second, third, fourth, fifth, and sixth switching transistors are all connected to a control terminal for turning off and on the switching transistors.

[0045] Preferably, the operating modes of the AC / DC conversion module include:

[0046] An input voltage V is applied between the first terminal and the third terminal of the AC / DC rectifier in ;

[0047] An output voltage V is output between the first output terminal and the second output terminal of the DC / DC step-down converter o ;

[0048] When |V in | < V o , the front-stage AC / DC rectifier operates in a high-frequency switching mode, rectifying the AC input V in into a DC voltage V o and outputting it, and the rear-stage DC / DC step-down converter is in a through state, that is, the fifth switching transistor is always on;

[0049] When |V in | > V o , the front-stage AC / DC rectifier is in a through state, that is, the AC / DC rectifier operates at the power frequency (V in > 0, Q1 and Q4 are in a through state, Q2 and Q3 are turned off; V in<0, Q2 is directly connected to Q3, Q1 and Q4 are turned off), and the DC output voltage V is obtained by high-frequency chopping of the post-stage DC / DC step-down converter o ;

[0050] Among them, the fact that the AC / DC rectifier operates at power frequency means that: V in >0, the first switch tube and the fourth switch tube are directly connected, and the second switch tube and the third switch tube are turned off; V in <0, the second switch tube and the third switch tube are directly connected, and the first switch tube and the fourth switch tube are turned off.

[0051] (III) Beneficial effects

[0052] The present invention provides a hydrogen production power supply circuit based on a first-stage high-frequency conversion. Compared with the prior art, it has the following beneficial effects:

[0053] The transformer + three independent AC / DC rectifiers and DC / DC step-down converters proposed in the embodiments of the present invention use high-frequency power electronic converters to replace the original thyristor rectification scheme, which can reduce the ripple of the output current, suppress the interference of harmonic currents, facilitate the control of various factors in the electrolysis production process, ensure the stability of the current density, thereby improving the electrolysis efficiency and increasing the output of electrolysis products. Brief description of the drawings

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only 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.

[0055] Figure 1 Shows an existing 12-pulse thyristor full-bridge rectifier

[0056] Figure 2 Is a schematic diagram of a traditional AC + DC two-stage architecture hydrogen production power supply circuit;

[0057] Figure 3 Is Figure 2 The circuit diagram of a typical circuit of;

[0058] Figure 4 Is a schematic diagram of the hydrogen production power supply circuit based on a first-stage high-frequency conversion in Embodiment 1;

[0059] Figure 5 Is the circuit diagram of the hydrogen production power supply circuit based on a first-stage high-frequency conversion in Embodiment 1;

[0060] Figure 6 Is the circuit diagram of a single-phase 1.5-level AC / DC conversion module;

[0061] Figure 7 is the voltage waveform of the bus capacitor C. Specific embodiments

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Apparently, the described embodiments are some, rather than all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0063] It should be noted that for the sake of convenience in description, the switching MOSFET is used as a representative of the controllable (turn-on and turn-off) switching tube in the embodiments of the present invention, but the switching tube in the present invention is not limited to the MOSFET. The MOSFET is taken as an example for illustration. The first end of the MOSFET refers to the drain, the second end refers to the source, and the control end refers to the gate. A drive control signal is applied to the control end of each switching tube in the embodiments of the present invention. For the sake of simplicity, it will not be elaborated hereinafter. The power switching tube in the embodiments of the present invention can also be implemented by other controllable switching tube devices other than the MOSFET, such as the IGBT. At the same time, in the embodiments of the present invention, to ensure the normal operation of each switching device, a freewheeling diode needs to be connected in parallel to each switching device. The parallel connection direction of the freewheeling diode is related to the type of the switching device, and those skilled in the art can set it according to the type of the switching device, which is not limited herein. If not specified, the switching device is default to include a freewheeling diode, and it will be pointed out in this embodiment in special cases.

[0064] The embodiments of the present application provide a hydrogen production power supply circuit based on a first-stage high-frequency conversion, which solves the technical problems of the existing 12-pulse thyristor rectification, such as low power factor, large harmonic current on the AC side power grid, and large ripple current on the DC side, and realizes the suppression of the harmonic current on the AC side power grid and the reduction of the ripple current on the DC side while improving the power factor of the rectification circuit, thereby improving the electrolytic hydrogen production efficiency.

[0065] The overall idea of the technical solutions in the embodiments of the present application to solve the above technical problems is as follows:

[0066] AC / DC hydrogen production power supplies can be mainly classified into single-stage, multi-stage, and hybrid parallel types according to their structures. Single-stage topologies can be divided into uncontrolled converters, semi-controlled converters, and PWM fully controlled converters according to the commutation method. The semiconductors used in the first two are diodes and thyristors respectively, and conduction or turn-off is naturally achieved in the power frequency cycle; while the latter uses expensive fully controlled devices with weak large current tolerance, resulting in reduced reliability and increased costs. Multi-stage topologies refer to the combination of different types of topologies with single-stage ones to make up for the deficiencies of single-stage topologies. Currently, the most widely used topology is the combination of an AC / DC converter and a DC / DC step-down transformer, which can achieve functions such as wide-range adjustment of the output voltage, effective reduction of the output ripple current, and improvement of the dynamic response speed. The hybrid parallel topology uses a parallel structure of a thyristor converter and a PWM converter. Since the PWM converter can be used as an active power filter to compensate for the grid-side harmonics of the thyristor converter, the harmonic distortion rate of the grid-side current is effectively reduced.

[0067] As Figure 1 shown, the 12-pulse thyristor full-bridge rectifier is the most widely used topology in industrial hydrogen production at present. The grid-side current of this topology is mainly 12k±1 harmonics, and the output current mainly contains 12k harmonics. There are still problems such as low power factor, large AC-side grid harmonic current, large DC-side ripple current, and slow dynamic response speed. And generally, when in use, due to its too narrow voltage adjustable range, a rectifier transformer device with on-load voltage regulation is usually installed before the thyristor rectification. The whole set of equipment is expensive and bulky.

[0068] As Figure 2 、 Figure 3 Figure is a traditional AC+DC two-stage architecture and a typical implementation circuit of it. The DC voltage obtained by its rectification is then subjected to step-down conversion. Compared with the previous scheme, it can achieve functions such as wide-range adjustment of the output voltage, effective reduction of the output ripple current, and improvement of the dynamic response speed. However, it is usually only applicable to medium and small power scenarios, and there is still room for further improvement in its power efficiency.

[0069] As can be seen from the above description, the original mainstream technical solution is 12-pulse thyristor rectification, which has problems such as low power factor, large harmonic current on the AC side of the power grid, large ripple current on the DC side, and slow dynamic response speed, thus reducing the electrolytic hydrogen production efficiency. At the same time, due to the narrow adjustable voltage range of thyristor rectification, the power supply load range is limited, so the rectifier transformer device needs to have an on-load tap-changing function, which increases the cost of the whole device. And this power supply solution is the traditional mainstream solution for high-power electrolysis industry. The thyristor works in the power frequency mode, and the power supply efficiency is lower than that of the new electrolytic power supply solution, and the annual power consumption of enterprises is high. Although the traditional AC+DC two-stage architecture solution can achieve functions such as wide-range adjustment of the output voltage, effective reduction of the output ripple current, and improvement of the dynamic response speed, it is usually only applicable to medium and small power scenarios, and there is still room for further improvement in its power supply efficiency.

[0070] To solve the above problems, the embodiment of the present invention adopts a high-frequency electrolytic power supply with a main circuit topology of a transformer + three independent 1.5-level AC / DC conversion modules. While improving the power factor of the rectifier circuit, it realizes the suppression of harmonic current on the AC side of the power grid and reduces the ripple current on the DC side, thereby improving the electrolytic hydrogen production efficiency. And the topology adopts high-frequency fully controlled devices and one-level energy conversion, which can improve the power supply efficiency and reduce the power loss, thus greatly reducing the power consumption cost of high-power electrolysis enterprises.

[0071] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0072] Embodiment 1:

[0073] The embodiment of the present invention provides a hydrogen production power supply circuit based on one-level high-frequency conversion, as Figure 4 shown. The circuit includes a pre-stage adjustable transformer, a first AC / DC conversion module, a second AC / DC conversion module, and a third AC / DC conversion module; the first AC / DC conversion module includes a first AC / DC rectifier, a first DC / DC step-down converter, and a first capacitor; the second AC / DC conversion module includes a second AC / DC rectifier, a second DC / DC step-down converter, and a second capacitor; the third AC / DC conversion module includes a third AC / DC rectifier, a third DC / DC step-down converter, and a third capacitor;

[0074] Among them, the pre-stage adjustable transformer includes a primary winding and a secondary winding. The primary winding is connected in a Δ shape, and the secondary winding includes three independent first side windings v 1, a second side winding v 2, and a third side winding v3; The first end of the first side winding is connected to the first end of the first AC / DC rectifier; the second end of the first side winding is connected to the third end of the first AC / DC rectifier; the first end of the second side winding is connected to the first end of the second AC / DC rectifier; the second end of the second side winding is connected to the third end of the second AC / DC rectifier; the first end of the third side winding is connected to the first end of the third AC / DC rectifier; the second end of the third side winding is connected to the third end of the third AC / DC rectifier;

[0075] The second end of the first AC / DC rectifier is connected to the first input terminal of the first DC / DC buck converter, and the fourth end of the first AC / DC rectifier is connected to the second input terminal of the first DC / DC buck converter; a first capacitor is connected between the first AC / DC rectifier and the first DC / DC buck converter;

[0076] The second end of the second AC / DC rectifier is connected to the first input terminal of the second DC / DC buck converter, and the fourth end of the second AC / DC rectifier is connected to the second input terminal of the second DC / DC buck converter; a second capacitor is connected between the second AC / DC rectifier and the second DC / DC buck converter;

[0077] The second end of the third AC / DC rectifier is connected to the first input terminal of the third DC / DC buck converter, and the fourth end of the third AC / DC rectifier is connected to the second input terminal of the third DC / DC buck converter; a third capacitor is connected between the third AC / DC rectifier and the third DC / DC buck converter;

[0078] The first output terminals of the three DC / DC buck converters are connected in parallel and then connected to the first end of the DC load;

[0079] The second output terminals of the three DC / DC buck converters are connected in parallel and then connected to the second end of the DC load.

[0080] The transformer + three independent AC / DC rectifiers and DC / DC buck converters proposed in the embodiments of the present invention use high-frequency power electronic converters to replace the original thyristor rectification scheme, which can reduce the ripple of the output current, suppress the interference of harmonic currents, facilitate the control of various factors in the electrolysis production process, ensure the stability of the current density, thereby realizing the improvement of the electrolysis efficiency and increasing the output of electrolytic products.

[0081] Embodiment 2:

[0082] A typical implementation circuit of the architecture of Embodiment 1 is as Figure 5As shown in the figure. The pre-stage transformer converts the three-phase AC voltage transmitted by the power grid into three independent single-phase AC voltages, and then the required DC electrolysis voltage is obtained through the 1.5-level AC / DC conversion module for each phase (that is, the AC / DC rectifier and the DC / DC step-down converter adopt a two-stage structure, but only one stage works in the power frequency mode at the same time). The three-phase interleaved parallel connection of the output can reduce the current stress of each switching tube while achieving the large electrolysis current required for electrolysis production, improve the reliability of the power supply system, and facilitate the selection of devices such as switching tubes. By adjusting the SPWM modulation ratio of the rectifier circuit and the duty cycle of the chopper circuit, the DC electrolysis voltage required for different electrolysis stages can be obtained to adapt to loads with different voltage levels.

[0083] It should be noted that the capacitors (C1, C2, C3) between the AC / DC rectifier and the DC / DC step-down converter are high-frequency thin-film capacitors. Compared with the electrolytic capacitors used in the traditional scheme, the capacitance value, volume are reduced, and the cost is reduced.

[0084] Taking a single phase as an example, the working principle of the 1.5-level AC / DC conversion module is introduced. The 1.5-level AC / DC conversion module is as Figure 6 shown. It can be seen that the converter is composed of a pre-stage PWM rectifier bridge and a post-stage chopper circuit. Q1-Q6 are switching tubes (it should be noted here that Q6 is a switching tube rather than a diode), C is the bus capacitor, L o and C f are the chopper output inductor and the filter capacitor respectively. The inductor L plays the role of filtering and charging / discharging energy in the circuit. In the specific implementation process, this inductor is omitted, and the AC / DC rectifier can still achieve the rectification function.

[0085] The waveform of the bus capacitor voltage of the converter is as Figure 7 shown. The main working principle of the topology is as follows: when |V in | < V o , the pre-stage rectifier bridge works in the high-frequency switching mode, rectifies the AC input V in into the DC voltage V o for output, and the post-stage Buck circuit (i.e., the DC / DC step-down converter) is directly connected, that is, Q5 is always on; when |V in | > V o , the pre-stage H4 is directly connected, that is, H4 works in the power frequency (V in > 0, Q1 and Q4 are directly connected, Q2 and Q3 are turned off; V in < 0, Q2 and Q3 are directly connected, Q1 and Q4 are turned off), and the post-stage Buck circuit performs high-frequency chopping to obtain the DC output voltage V o . The topology adopts a two-stage structure, but only one stage works in the power frequency mode at the same time, so it is called 1.5-level conversion, and the energy is one-level conversion.

[0086] In summary, compared with the prior art, the following beneficial effects are achieved:

[0087] 1. The transformer + three independent AC / DC rectifiers and DC / DC step-down converters proposed in the embodiments of the present invention use high-frequency power electronic converters to replace the original thyristor rectification scheme, which can reduce the ripple of the output current, suppress the interference of harmonic currents, facilitate the control of various factors in the electrolysis production process, ensure the stability of the current density, and thus improve the electrolysis efficiency and increase the output of electrolytic products.

[0088] 2. The transformer + 1.5-level AC / DC conversion module proposed in the embodiments of the present invention causes less fluctuations in factors affecting electrolysis production such as the current density in the electrolytic cell and the concentration of the electrolytic cell solution compared with the traditional transformer + thyristor scheme, which is more conducive to the stable control of various factors in the electrolysis production process. While improving the hydrogen production efficiency, it can also improve its purity. The 1.5-level AC / DC conversion module is actually a first-level conversion of energy, which can further improve the power supply efficiency, increase the utilization rate of electric energy, reduce the electricity cost, and at the same time, the capacitors used are high-frequency thin-film capacitors, and compared with the electrolytic capacitors in the traditional scheme, the capacitance value, volume, and cost are significantly reduced, achieving the purpose of cost reduction and efficiency increase.

[0089] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen production power supply circuit based on a first-stage high-frequency conversion, characterized in that, It includes a pre-stage adjustable transformer and three independent AC / DC conversion modules; the pre-stage adjustable transformer includes a primary winding and a secondary winding, the primary winding is connected in delta, and the secondary winding includes three independent side windings; each AC / DC conversion module includes an AC / DC rectifier, a DC / DC step-down converter and a capacitor, Among them, the connection method in each AC / DC conversion module includes: The first end of the side winding is connected to the first end of the AC / DC rectifier; The second end of the side winding is connected to the third end of the AC / DC rectifier; The second end of the AC / DC rectifier is connected to the first input end of the DC / DC step-down converter; The fourth end of the AC / DC rectifier is connected to the second input end of the DC / DC step-down converter; a capacitor is connected between the AC / DC rectifier and the DC / DC step-down converter; The first output ends of the three DC / DC step-down converters are connected in parallel and then connected to the first end of the DC load; The second output ends of the three DC / DC step-down converters are connected in parallel and then connected to the second end of the DC load; There are several switching tubes in the three AC / DC conversion modules. By controlling the turn-off and conduction of the switching tubes, the AC / DC rectifier and the DC / DC step-down converter in each AC / DC conversion module adopt a two-stage structure of pre-stage and post-stage. During the working process, one stage always works in the power frequency mode at the same time. The three independent AC / DC conversion modules are all 1.5-stage AC / DC conversion modules, which is the first-stage conversion of energy; The three AC / DC rectifiers all include the first, second, third and fourth switching tubes; Among them, the second end of the first switching tube is connected to the first end of the second switching tube, and their common end is connected to the first end of the AC / DC rectifier; The first end of the first switching tube is connected to the first end of the third switching tube, serving as the second end of the AC / DC rectifier; The second end of the second switching tube is connected to the second end of the fourth switching tube, serving as the fourth end of the AC / DC rectifier; The first end of the fourth switching tube is connected to the second end of the third switching tube, serving as the third end of the AC / DC rectifier; The third ends of the first, second, third and fourth switching tubes are all connected to the control end for the turn-off and conduction of the switching tubes; Among them, the three DC / DC step-down converters all include a fifth switching tube, a sixth switching tube, an output inductor and a filter capacitor; The second end of the fifth switching tube is connected to the first end of the sixth switching tube; the connection end of the fifth switching tube and the sixth switching tube is connected to the output inductor and then serves as the first output end of the DC / DC step-down converter; The fourth end of the AC / DC rectifier is connected to the common end of the sixth switching tube on the second output end of the DC / DC step-down converter; The filter capacitor is connected between the first output end and the second output end of the DC / DC step-down converter; The capacitor in each AC / DC conversion module is a bus capacitor, and both ends of the bus capacitor are respectively connected to the second end and the fourth end of the AC / DC rectifier; The third ends of the first, second, third, fourth, fifth and sixth switching tubes are all connected to the control end for the turn-off and conduction of the switching tubes; The working modes of the AC / DC conversion module include: The input voltage V between the first and third terminals of the AC / DC rectifier in ; The output voltage V is output between the first output terminal and the second output terminal of the DC / DC step-down voltage regulator o ; When |V in | < V o When, the front - stage AC / DC rectifier operates in a high - frequency switching mode, rectifying the AC input V in into a DC voltage V o output. The rear - stage DC / DC buck converter is in a through - connection state, that is, the fifth switching transistor is always on; When |V in | > V o When |V|< V o , the front-end AC / DC rectifier is in direct-through mode, that is, the AC / DC rectifier operates at the power frequency, and the rear-end DC / DC buck converter performs high-frequency chopping to obtain the DC output voltage V o ; Among them, the fact that the AC / DC rectifier operates at the power frequency means that: V in > 0, the first switching tube and the fourth switching tube are directly connected, and the second switching tube and the third switching tube are turned off; V in < 0, the second switching tube and the third switching tube are directly connected, and the first switching tube and the fourth switching tube are turned off.

2. The hydrogen production power supply circuit based on the first-level high-frequency conversion according to claim 1, wherein The capacitors in the three independent AC / DC conversion modules are all high-frequency capacitors.

3. The hydrogen production power supply circuit based on the first-stage high-frequency conversion according to claim 1, characterized in that, The three AC / DC rectifiers each further include an inductor. The first end of the inductor is connected to the first end of the AC / DC rectifier, and the second end of the inductor is connected to the common end of the first switch tube and the second switch tube.

4. The hydrogen production power supply circuit based on the first-stage high-frequency conversion according to claim 1, wherein, The three DC / DC step-down voltage regulators each include a fifth switch tube, a sixth switch tube, an output inductor, and a filter capacitor; Among them, The first end of the fifth switch tube is the first input terminal of the DC / DC step-down voltage regulator; The second end of the fifth switch tube is connected to the first end of the sixth switch tube; The connection end of the fifth switch tube and the sixth switch tube is connected to the output inductor and then serves as the first output terminal of the DC / DC step-down voltage regulator; The second end of the sixth switch tube is connected between the second input terminal and the second output terminal of the DC / DC step-down voltage regulator; The filter capacitor is connected between the first output terminal and the second output terminal of the DC / DC step-down voltage regulator; The third ends of the fifth and sixth switch tubes are both connected to the control terminal for turning off and on the switch tubes.

5. The hydrogen production power supply circuit based on the first-stage high-frequency conversion according to any one of claims 1 to 4, characterized in that By adjusting the SPWM modulation ratio of the AC / DC rectifier and the duty cycle of the DC / DC step-down voltage regulator, the DC electrolysis voltage required in different electrolysis stages is obtained to adapt to loads of different voltage levels.

6. The hydrogen production power supply circuit based on the first-stage high-frequency conversion according to any one of claims 1 to 4, characterized in that, The switch tube includes a MOSFET.

7. The hydrogen production power supply circuit based on primary high-frequency conversion according to any one of claims 1 to 4, characterized in that, The capacitor is a high-frequency thin-film capacitor.

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