High-power water electrolysis hydrogen production converter suitable for new energy scene

Abstract

The invention discloses a high-power water electrolysis hydrogen production converter suitable for a new energy scene, and the technical scheme is that the high-power water electrolysis hydrogen production converter suitable for the new energy scene comprises a power grid, a rectification unit, a conversion unit and a load; the rectification unit is a multi-level rectifier, the input end is in three-phase alternating current connection with the output end of a power grid, and the output end is a direct-current bus which is provided with a plurality of first capacitors in series. The conversion unit comprises a plurality of LLC resonant conversion modules; the input end of the LLC resonant conversion module is connected with the two ends of the corresponding first capacitor; the output ends of the LLC resonant conversion modules are connected in parallel with the two ends of a load. The high-power water electrolysis hydrogen production converter suitable for the new energy scene has the advantages that the high-power water electrolysis hydrogen production converter suitable for the new energy scene meets the high-power and high-current operation scene and the low-voltage output requirement of a hydrogen production system, fault redundancy control is achieved, and the electric energy conversion efficiency under wide-power-range fluctuation is improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a high-power water electrolysis converter for hydrogen production suitable for new energy scenarios. Background Art

[0002] Large-scale hydrogen production technology is an effective way to achieve a high proportion of renewable energy consumption and ensure national energy security. The hydrogen production converter is an electric energy conversion device that connects the power grid and the hydrogen production system, and is the core component of the water electrolysis hydrogen production system. Due to the volatility and intermittent characteristics of new energy power generation, the operating power of the electrolysis hydrogen production system changes dynamically between 0-100%. On the one hand, the wide range of input voltage puts higher requirements on the gain range and step-down ratio of the hydrogen production converter. On the other hand, the hydrogen production converter is usually most efficient at the rated operating point, and the wide range of power fluctuations causes the hydrogen production converter to deviate from the optimal efficiency operating point most of the time, resulting in low overall operating efficiency. The existing hydrogen production converter technology cannot meet the needs of fluctuating hydrogen production scenarios due to its small voltage gain range and low wide range working efficiency. It is urgent to develop a high-power water electrolysis hydrogen production converter suitable for new energy scenarios. Summary of the invention

[0003] In order to solve the above-mentioned problems in the prior art, the present invention provides a high-power water electrolysis converter for hydrogen production suitable for new energy scenarios, so as to solve the demand for wide voltage gain of the hydrogen production converter under the wide input voltage range of new energy volatility input, and improve the power conversion efficiency under wide power range fluctuations.

[0004] In order to achieve the above-mentioned invention object, the present invention provides a high-power water electrolysis hydrogen production converter suitable for new energy scenarios, including a power grid, a rectifier unit, a conversion unit and a load;

[0005] The rectifier unit is a multi-level rectifier, the input end of the multi-level rectifier is connected to the output end of the power grid in three-phase AC, the output end of the multi-level rectifier is a DC bus, and a plurality of first capacitors are arranged in series on the DC bus, and the first capacitors are used to output voltage;

[0006] The conversion unit includes a plurality of LLC resonant conversion modules corresponding to a plurality of the first capacitors one by one; the input ends of the LLC resonant conversion modules are connected to the two ends of the corresponding first capacitors; and the output ends of the plurality of LLC resonant conversion modules are connected in parallel to the two ends of the load.

[0007] Further, the LLC resonant conversion module includes an inverter circuit, a resonant circuit, a high-frequency transformer and an output rectifier circuit;

[0008] The inverter circuit is a fully controlled full-bridge circuit or a fully controlled half-bridge circuit, the input end of the inverter circuit is connected to the corresponding two ends of the first capacitor, and the output end is connected to the input end of the resonant circuit;

[0009] The output end of the resonant circuit is connected to the input end of the high frequency transformer;

[0010] The input end of the output rectifier circuit is connected to the output end of the high-frequency transformer, and the output end of the output rectifier circuit is a DC output and is connected to both ends of the load.

[0011] Further, the inverter circuit includes a first bridge arm controlled by switch one, a second bridge arm controlled by switch two, a third bridge arm controlled by switch three, and a fourth bridge arm controlled by switch four;

[0012] The first bridge arm and the third bridge arm are connected in series to form a first series circuit, the second bridge arm and the fourth bridge arm are connected in series to form a second series circuit, and the first series circuit and the second series circuit are connected in parallel to two ends of the corresponding first capacitor;

[0013] The series circuit 1 includes a center 1, and the center 1 is a series connection point of the first bridge arm and the third bridge arm;

[0014] The second series circuit includes a second center, and the second center is a series connection point of the second bridge arm and the fourth bridge arm;

[0015] The input end of the resonant circuit is connected to the center one and the center two.

[0016] Furthermore, the switch one, the switch two, the switch three, and the switch four are MOSFETs or IGBTs.

[0017] Further, the resonant circuit comprises a first inductor, a second inductor and a second capacitor connected in series in sequence;

[0018] The second inductor is connected in parallel to both ends of the primary side of the high-frequency transformer, or the second inductor is the excitation inductor of the high-frequency transformer.

[0019] Furthermore, the output rectifier circuit is a full-bridge rectifier circuit or a full-wave rectifier circuit.

[0020] Further, the output rectifier circuit includes a fifth bridge arm controlled by switch five, a sixth bridge arm controlled by switch six, a seventh bridge arm controlled by switch seven, and an eighth bridge arm controlled by switch eight;

[0021] The fifth bridge arm and the seventh bridge arm are connected in series to form a series circuit three, the sixth bridge arm and the eighth bridge arm are connected in series to form a series circuit four, and the series circuit three and the series circuit four are connected in parallel to two ends of the load;

[0022] The series circuit three includes a center three, and the center three is a series connection point between the fifth bridge arm and the seventh bridge arm;

[0023] The series circuit four includes a center four, and the center four is a series connection point between the sixth bridge arm and the eighth bridge arm;

[0024] One end of the secondary side of the high-frequency transformer is connected to the central third electrical device, and the other end is connected to the central fourth electrical device.

[0025] Furthermore, the switch five, the switch six, the switch seven, and the switch eight are uncontrolled devices or controllable devices or a combination of uncontrolled devices and controllable devices.

[0026] Furthermore, the uncontrolled device is a diode, and the controllable device is a thyristor, a MOSFET, or an IGBT.

[0027] Furthermore, the rectifying unit is a three-level rectifier.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention realizes modular design of the conversion unit by one-to-one correspondence between the first capacitor and the LLC resonant conversion module, which is conducive to improving the power conversion efficiency under wide power range fluctuations: different numbers of LLC resonant conversion modules can be switched on and off at different powers to meet the power operation capacity requirements, thereby achieving efficiency improvement in a wide power range under new energy fluctuation input;

[0030] 2. The present invention facilitates fault redundancy control through modular design of the conversion unit, that is, the LLC resonant conversion module can select to cut off the corresponding fault phase without shutting down in the event of a fault, which can reduce the impact of power shutdown on the life of the electrolytic stack;

[0031] 3. The front stage of the present invention adopts a multi-level rectifier, which can meet the requirements of high-power operating conditions on the rectifier side. At the same time, the switching devices in the multi-level rectifier can be controlled to achieve fast dynamic response and flexible adjustment of the output voltage values ​​of several first capacitors. The input end of the LLC resonant conversion module is set at both ends of each first capacitor set in series, which increases a current sharing control degree of freedom compared to connecting several LLC resonant conversion modules to the same input; the rear stage adopts the LLC resonant conversion module to further adjust the output DC voltage. Several LLC resonant conversion modules can increase the output current and reduce the output ripple by connecting them in parallel at the output end, and have modular characteristics, which is convenient for realizing load change, fault phase shedding and high-power expansion;

[0032] 4. The high-frequency transformer in the LLC resonant conversion module of the present invention has the advantages of small size and high power density, and can realize electrical isolation between the input side and the output side. By designing the turns ratio of the transformer and increasing the step-down ratio, low-voltage output can be achieved, thus meeting the requirements of low-voltage power supply for the hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the structure of an embodiment of the present invention;

[0034] Figure 2 It is a schematic diagram of a local circuit structure of a conversion unit in the present invention;

[0035] Figure 3 It is a structural schematic diagram of another embodiment of the present invention.

[0036] Among them, the figure markings are: 1, rectification unit; 11, first capacitor; 2, conversion unit; 20, LLC resonant conversion module; 210, inverter circuit; 211, switch one; 212, switch two; 213, switch three; 214, switch four; 220, resonant circuit; 221, first inductor; 222, second capacitor; 223, second inductor; 230, high-frequency transformer; 240, output rectification circuit; 241, switch five; 242, switch six; 243, switch seven; 244, switch eight; 3, power grid; 4, load; 5, third capacitor. DETAILED DESCRIPTION

[0037] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0038] See also Figure 1 , the embodiment of the present invention provides a high-power water electrolysis hydrogen production converter suitable for new energy scenarios, including a power grid 3, a rectifier unit 1, a conversion unit 2 and a load 4;

[0039] The rectifier unit 1 and the conversion unit 2 are arranged between the power grid 3 and the load 4. The rectifier unit 1 is used to convert the AC signal of the power grid 3 into a DC signal and transmit it to the conversion unit 2. The conversion unit 2 is used to supply power to the load 4.

[0040] The rectifier unit 1 is a multi-level rectifier, the input end of the multi-level rectifier is connected to the output end of the power grid 3 in three-phase AC, the output end is a DC bus, and a plurality of first capacitors 11 are arranged in series on the DC bus, and the first capacitors 11 are used to output voltage;

[0041] The conversion unit 2 includes a plurality of LLC resonant conversion modules 20 corresponding to a plurality of first capacitors 11 one by one. The modular design is conducive to improving the efficiency of electric energy conversion under wide power range fluctuations: the modularly designed conversion unit 2 can solve the problem of low converter efficiency under wide power input. Through design, different numbers of LLC resonant conversion modules 20 can be switched under different powers. For example, all LLC resonant conversion modules 20 are put into operation under high power conditions to meet the power operation capacity requirements, and an appropriate number of LLC resonant conversion modules 20 are switched under low power conditions to meet the power operation requirements. By reducing the number of LLC resonant conversion modules 20 in operation, power loss is reduced, and the operating efficiency under low power is improved, thereby achieving efficiency improvement in a wide power range under new energy fluctuation input. In addition, the modular design facilitates fault redundancy control: the LLC resonant conversion module 20 can choose to cut off the corresponding fault phase without shutting down in the event of a fault, which can reduce the impact of power shutdown on the life of the electrolytic stack.

[0042] The input end of the LLC resonant conversion module 20 is connected to the two ends of the corresponding first capacitor 11 ; the output ends of a plurality of LLC resonant conversion modules 20 are connected in parallel to the two ends of the load 4 .

[0043] The rectifier unit 1 adopts a multi-level rectifier, which can meet the requirements of high-power operating conditions on the rectifier side. At the same time, it can achieve fast dynamic response and flexible adjustment of the output voltage values ​​of several first capacitors 11 by controlling the switching devices in the multi-level rectifier. The input end of the LLC resonant conversion module is set at both ends of each first capacitor set in series, which adds an additional degree of freedom of current sharing control compared to connecting several LLC resonant conversion modules 20 to the same input; the conversion unit 2 adopts the LLC resonant conversion module 20 to further adjust the output DC voltage. Several LLC resonant conversion modules 20 can increase the output current and reduce the output ripple by connecting them in parallel at the output end, and have modular characteristics, which is convenient for realizing load variation, fault phase cutting and high-power expansion.

[0044] In one preferred embodiment, the LLC resonant conversion module 20 includes an inverter circuit 210, a resonant circuit 220, a high-frequency transformer 230 and an output rectifier circuit 240; a third capacitor 5 is connected in parallel at both ends of the load 4;

[0045] The inverter circuit 210 is a fully controlled full-bridge circuit or a fully controlled half-bridge circuit. On the one hand, the DC signal output by the previous stage can be converted into a high-frequency AC signal; on the other hand, soft switching can be achieved by controlling the switching frequency to match the resonant frequency of the resonant circuit, thereby reducing switching losses and improving the power conversion efficiency; the input end of the inverter circuit 210 is connected to the corresponding two ends of the first capacitor 11, and the output end is connected to the input end of the resonant circuit 220 in a single-phase AC connection, and the resonant frequency is adjusted by designing the parameters of the inductor and capacitor 222 in the resonant circuit 220;

[0046] The output end of the resonant circuit 220 is electrically connected to the input end of the high-frequency transformer 230. The high-frequency transformer 230 has the advantages of small size and high power density, and can achieve electrical isolation between the input side and the output side. The voltage is reduced by designing the turns ratio of the high-frequency transformer 230 to meet the low-voltage power supply requirements of the hydrogen production system.

[0047] The input end of the output rectifier circuit 240 is connected to the output end of the high-frequency transformer 230 in single-phase AC mode, and the output end of the output rectifier circuit 240 is a DC output and is connected to both ends of the load 4 .

[0048] In one preferred embodiment, the inverter circuit 210 includes a first bridge arm controlled by a switch 1 211 , a second bridge arm controlled by a switch 212 , a third bridge arm controlled by a switch 3 213 , and a fourth bridge arm controlled by a switch 4 214 ;

[0049] The first bridge arm and the third bridge arm are connected in series to form a series circuit 1, the second bridge arm and the fourth bridge arm are connected in series to form a series circuit 2, and the series circuit 1 and the series circuit 2 are connected in parallel to the corresponding two ends of the first capacitor 11;

[0050] The drain or collector of switch 1 211 and the drain or collector of switch 2 212 are connected to the positive electrode of the first capacitor 11 respectively, the source or emitter of switch 1 211 is connected to the drain or collector of switch 3 213, the source or emitter of switch 2 212 is connected to the drain or collector of switch 4 214, and the source or emitter of switch 3 213 and the source or emitter of switch 4 214 are connected to the negative electrode of the first capacitor 11 respectively; switch 1 211, switch 2 212, switch 3 213, and switch 4 214 are all switching devices of the inverter circuit 210, and the names of the connection terminals are determined according to the types of the switching devices, such as the positive current output terminal of the switching device: when the switching device is an IGBT, it is the collector, and in MOSFET, it is the drain; the negative current (or return current) input terminal of the switching device: when the switching device is an IGBT, it is the emitter, and in MOSFET, it is the source; for other switching devices or non-standard switching devices, the specific terminal naming may be different, and they are also applicable to the present embodiment;

[0051] The series circuit 1 includes a center 1, which is a series connection point between the first bridge arm and the third bridge arm;

[0052] The second series circuit includes a second center, which is a series connection point between the second bridge arm and the fourth bridge arm;

[0053] One end of the input end of the resonant circuit 220 is electrically connected to the center 1, and the other end is electrically connected to the center 2. Preferably, the input end of the resonant circuit 220 is connected to the center 1 and the center 2 in a single-phase alternating current.

[0054] In one preferred embodiment, the switch 1 211 , the switch 212 , the switch 3 213 , and the switch 4 214 are MOSFETs or IGBTs. In addition, other switch devices are also applicable to the present invention.

[0055] In one preferred embodiment, the resonant circuit 220 includes a first inductor 221, a second inductor 223, and a second capacitor 222 connected in series in sequence, and the resonant frequency is adjusted by designing the parameters of the first inductor 221, the second inductor 223, and the second capacitor 222;

[0056] The second inductor 223 is connected in parallel to both ends of the primary side of the high-frequency transformer 230 , or the second inductor is the excitation inductor of the high-frequency transformer.

[0057] Preferably, the high frequency transformer 230 includes an input inductor;

[0058] The second inductor 223 is connected in parallel with the input inductor.

[0059] In one preferred embodiment, the output rectifier circuit 240 is a full-bridge rectifier circuit or a full-wave rectifier circuit.

[0060] In one preferred embodiment, the output rectifier circuit 240 includes a fifth bridge arm controlled by a switch five 241, a sixth bridge arm controlled by a switch six 242, a seventh bridge arm controlled by a switch seven 243, and an eighth bridge arm controlled by a switch eight 244;

[0061] The fifth bridge arm and the seventh bridge arm are connected in series to form a series circuit three, the sixth bridge arm and the eighth bridge arm are connected in series to form a series circuit four, and the series circuit three and the series circuit four are connected in parallel to two ends of the load 4;

[0062] The series line three includes a center three, which is a series connection point of the fifth bridge arm and the seventh bridge arm;

[0063] The series line 4 includes a center 4, which is a series connection point between the sixth bridge arm and the eighth bridge arm;

[0064] One end of the secondary side of the high-frequency transformer 230 is electrically connected to the center three, and the other end is electrically connected to the center four. Preferably, the output end of the high-frequency transformer 230 is connected to the center three and the center four in single-phase AC.

[0065] In one of the preferred embodiments, switch five 241, switch six 242, switch seven 243, and switch eight 244 are uncontrolled devices or controllable devices or a combination of uncontrolled devices and controllable devices, wherein when switch five 241, switch six 242, switch seven 243, and switch eight 244 are a combination of uncontrolled devices and controllable devices, any one, two, or three of them are controllable devices, and the output voltage of the conversion unit is adjusted by adjusting the control variables such as the duty cycle and phase shift angle of the switch device, further improving the step-down ratio and voltage gain, and ensuring low voltage output under a wide range of input at a low cost. In one of the preferred embodiments, the uncontrolled device is a diode, and the controllable device is a thyristor, a MOSFET, or an IGBT. In addition, other uncontrolled devices or controllable devices are also applicable to the present invention.

[0066] In one preferred embodiment, the rectifier unit 1 is a three-level rectifier, which is suitable for use in medium-voltage and high-power conditions, can reduce energy waste, improve rectification efficiency, and can more effectively convert electrical energy and reduce energy loss compared to a multi-level rectifier. In addition, it has the advantages of high reliability, good adjustability, harmonic reduction, simple topology, mature technology, and cost optimization, and is suitable for popularization and use. The number of first capacitors 11 in the three-level rectifier is two, which are usually referred to as upper bus capacitors and lower bus capacitors. The number of LLC resonant conversion modules 20 corresponding to the two first capacitors 11 is two, and the inputs of the two groups of LLC resonant conversion modules 20 are respectively connected to the upper bus capacitor and the lower bus capacitor of the three-level rectifier. The current sharing control can be achieved by adjusting the voltage values ​​of the upper bus capacitor and the lower bus capacitor, that is, the input voltage value of the LLC resonant conversion module 20; in addition, in addition to the attached Figure 1 In addition to the three-level rectifier described in the embodiment, other types of three-level rectifiers are also applicable to the solution of this embodiment.

[0067] The system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art may understand and implement it without creative work.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-power water electrolysis hydrogen production converter suitable for new energy scenarios, characterized in that: Including power grid, rectifier unit, conversion unit and load; The rectifier unit is a multi-level rectifier, the input end of the multi-level rectifier is connected to the output end of the power grid in three-phase AC, the output end of the multi-level rectifier is a DC bus, and a plurality of first capacitors are arranged in series on the DC bus, and the first capacitors are used to output voltage; The conversion unit includes a plurality of LLC resonant conversion modules corresponding to a plurality of the first capacitors one by one; the input ends of the LLC resonant conversion modules are connected to the two ends of the corresponding first capacitors; and the output ends of the plurality of LLC resonant conversion modules are connected in parallel to the two ends of the load.

2. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 1 is characterized in that: The LLC resonant conversion module includes an inverter circuit, a resonant circuit, a high-frequency transformer and an output rectifier circuit; The inverter circuit is a fully controlled full-bridge circuit or a fully controlled half-bridge circuit, the input end of the inverter circuit is connected to the corresponding two ends of the first capacitor, and the output end is connected to the input end of the resonant circuit; The output end of the resonant circuit is connected to the input end of the high frequency transformer; The input end of the output rectifier circuit is connected to the output end of the high-frequency transformer, and the output end of the output rectifier circuit is a DC output and is connected to both ends of the load.

3. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 2 is characterized in that: The inverter circuit comprises a first bridge arm controlled by switch one, a second bridge arm controlled by switch two, a third bridge arm controlled by switch three, and a fourth bridge arm controlled by switch four; The first bridge arm and the third bridge arm are connected in series to form a first series circuit, the second bridge arm and the fourth bridge arm are connected in series to form a second series circuit, and the first series circuit and the second series circuit are connected in parallel to two ends of the corresponding first capacitor; The series circuit 1 includes a center 1, and the center 1 is a series connection point of the first bridge arm and the third bridge arm; The second series circuit includes a second center, and the second center is a series connection point of the second bridge arm and the fourth bridge arm; The input end of the resonant circuit is connected to the center one and the center two.

4. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 3 is characterized in that: The switch 1, the switch 2, the switch 3, and the switch 4 are MOSFETs or IGBTs.

5. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 2 is characterized in that: The resonant circuit comprises a first inductor, a second inductor and a second capacitor connected in series in sequence; The second inductor is connected in parallel to both ends of the primary side of the high-frequency transformer, or the second inductor is the excitation inductor of the high-frequency transformer.

6. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 2 is characterized in that: The output rectifier circuit is a full-bridge rectifier circuit or a full-wave rectifier circuit.

7. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 6 is characterized in that: The output rectifier circuit includes a fifth bridge arm controlled by switch five, a sixth bridge arm controlled by switch six, a seventh bridge arm controlled by switch seven, and an eighth bridge arm controlled by switch eight; The fifth bridge arm and the seventh bridge arm are connected in series to form a series circuit three, the sixth bridge arm and the eighth bridge arm are connected in series to form a series circuit four, and the series circuit three and the series circuit four are connected in parallel to two ends of the load; The series circuit three includes a center three, and the center three is a series connection point between the fifth bridge arm and the seventh bridge arm; The series circuit four includes a center four, and the center four is a series connection point between the sixth bridge arm and the eighth bridge arm; One end of the secondary side of the high-frequency transformer is connected to the central third electrical device, and the other end is connected to the central fourth electrical device.

8. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 7 is characterized in that: The switch five, the switch six, the switch seven, and the switch eight are uncontrolled devices or controllable devices or a combination of uncontrolled devices and controllable devices.

9. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to claim 8, characterized in that: The uncontrolled device is a diode, and the controllable device is a thyristor, a MOSFET, or an IGBT.

10. The high-power water electrolysis hydrogen production converter suitable for new energy scenarios according to any one of claims 1 to 9, characterized in that: The rectifying unit is a three-level rectifier.

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