Multi-machine parallel current source type rectification hydrogen production power supply with low step-down ratio and control method thereof

Abstract

The invention discloses a multi-machine parallel current source type rectification hydrogen production power supply with a low step-down ratio and a control method thereof, the multi-machine parallel current source type rectification hydrogen production power supply comprises a three-phase alternating current input busbar comprising an A-phase busbar, a B-phase busbar, a C-phase busbar and a neutral busbar N; the direct current output busbar comprises a direct current positive busbar DC + and a direct current negative busbar DC-; the at least three rectification power units are respectively connected in series between the A-phase busbar and the neutral busbar N, between the B-phase busbar and the neutral busbar N and between the C-phase busbar and the neutral busbar N according to phases on the alternating current side, so that the A phase, the B phase and the C phase respectively form an input series link formed by the at least three rectification power units; and the direct current positive output end and the direct current negative output end of each rectification power unit are respectively connected in parallel with the direct current positive busbar DC + and the direct current negative busbar DC-. According to the invention, the power supply requirement of the low-voltage large-current hydrogen production load can be met, and the capacity can be expanded.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronic conversion and power supply control for electrolytic hydrogen production, and particularly relates to a multi-machine parallel current source type rectification hydrogen production power supply with low voltage reduction ratio and a control method thereof. BACKGROUND

[0002] The electrolytic hydrogen production load usually has the characteristics of low voltage, large current, strong nonlinearity and dynamic fluctuation, and the rectification hydrogen production power supply needs to provide stable direct current output current under a wide working condition. When facing low-voltage and large-current output, the existing current source type rectifier often needs to realize a large voltage conversion amplitude (i.e. large voltage reduction ratio), which easily leads to the increase of voltage / current stress of power devices, the reduction of control margin, and the limitation of efficiency and reliability. At the same time, the low-voltage and large-current scene is sensitive to the output current ripple, and a larger output current ripple may cause the electrolytic cell to run fluctuation and affect the system stability.

[0003] Therefore, there is an urgent need for a rectification hydrogen production power supply which can reduce the demand for single-machine large voltage reduction ratio and take into account the output current ripple suppression. SUMMARY

[0004] In view of the above problems, the application provides a multi-machine parallel current source type rectification hydrogen production power supply with low voltage reduction ratio and a control method thereof, which can meet the power supply demand of low-voltage and large-current hydrogen production load and realize capacity expansion.

[0005] In order to achieve the above technical purposes and achieve the above technical effects, the application realizes the following technical solutions:

[0006] In a first aspect, the application provides a multi-machine parallel current source type rectification hydrogen production power supply with low voltage reduction ratio, comprising:

[0007] A three-phase alternating current input busbar, comprising an A-phase busbar, a B-phase busbar, a C-phase busbar and a neutral busbar N;

[0008] A direct current output busbar, comprising a direct current positive busbar DC+ and a direct current negative busbar DC-;

[0009] At least three rectification power units, each rectification power unit is connected in series according to phase at the alternating current side between the A-phase busbar and the neutral busbar N, between the B-phase busbar and the neutral busbar N, and between the C-phase busbar and the neutral busbar N, so that the A-phase, the B-phase and the C-phase form input series links composed of the at least three rectification power units; the direct current positive output end and the direct current negative output end of each rectification power unit are connected in parallel to the direct current positive busbar DC+ and the direct current negative busbar DC- respectively.

[0010] In conjunction with the first aspect, optionally, each of the rectifier power units includes at least three independent A-phase full-bridge submodules, B-phase full-bridge submodules, and C-phase full-bridge submodules. The A-phase full-bridge submodules, B-phase full-bridge submodules, and C-phase full-bridge submodules have the same structure and each includes:

[0011] The circuit consists of a first controllable switch device S1, a second controllable switch device S2, a third controllable switch device S3, and a fourth controllable switch device S4. The first controllable switch device S1 and the third controllable switch device S3 are connected in series to form a first bridge arm, the second controllable switch device S2 and the fourth controllable switch device S4 are connected in series to form a second bridge arm, and the first bridge arm and the second bridge arm are connected in parallel to form a full bridge circuit.

[0012] The AC side series inductor Ls is connected in series between the corresponding phase busbar and the AC input terminal of the corresponding full-bridge circuit;

[0013] A parallel capacitor Cs is connected on the AC side, and is set in parallel between the corresponding phase busbar and the corresponding neutral busbar N.

[0014] The DC-side output inductor Lo is connected in series on the DC output branch of the corresponding full-bridge submodule.

[0015] In conjunction with the first aspect, optionally, the DC output branches in each of the rectifier power units are independent of each other, and the DC output branches are combined to form the DC positive output terminal and the DC negative output terminal of the rectifier power unit. The DC positive output terminal is connected to the DC positive busbar DC+, and the DC negative output terminal is connected to the DC negative busbar DC-.

[0016] In conjunction with the first aspect, optionally, the A-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, ..., and the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming the input series link of the A-phase.

[0017] The B-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, ..., and the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming the input series link of the B-phase.

[0018] The C-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, and so on, until the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming a C-phase input series link.

[0019] In conjunction with the first aspect, optionally, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply further includes an input voltage equalization control unit. The input voltage equalization control unit samples the voltage of the parallel capacitor Cs on the AC side of each rectifier power unit in the A-phase, B-phase, and C-phase input series links; sums the voltages of the parallel capacitor Cs on the AC side of the same phase in each rectifier power unit and divides them by the number of rectifier power units to obtain the equalization setpoint for that phase; and compares the voltage of the parallel capacitor Cs on the AC side of that phase in each rectifier power unit with the equalization setpoint for that phase to obtain the equalization setpoint for each rectifier power unit. The voltage equalization deviation of this phase in each rectifier power unit is determined. The voltage equalization deviation of this phase in each rectifier power unit is adjusted by PR to obtain the voltage equalization compensation amount of this phase in each rectifier power unit. The voltage equalization compensation amount of this phase in each rectifier power unit is used to adjust the reference voltage modulation signal of this phase in each rectifier power unit to obtain the voltage modulation signal of the AC side parallel capacitor Cs of this phase in each rectifier power unit. The voltage modulation signal is processed into a PWM signal and then applied to each controllable switching device in the rectifier power unit so that the input distribution voltage of each rectifier power unit in the input series link of each phase tends to be balanced.

[0020] In conjunction with the first aspect, optionally, The formula for calculating the equalization pressure setpoint of the phase is:

[0021] ,

[0022] In the formula, for The given value for the equalization pressure of the phase; For the first One rectifier power unit The voltage of the parallel capacitor Cs on the AC side of the phase, ; This refers to the number of rectifier power units;

[0023] No. One rectifier power unit The formula for calculating the phase equalization deviation is:

[0024] ,

[0025] In the formula, For the first One rectifier power unit Phase pressure uniformity deviation;

[0026] No. One rectifier power unit The formula for calculating the equalization compensation of the phase is:

[0027] ,

[0028] In the formula, For the first One rectifier power unit Phase equalization compensation amount For PR controller functions;

[0029] No. One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase is:

[0030] ,

[0031] In the formula, For the first One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase. for The reference voltage modulation signal for the phase.

[0032] In conjunction with the first aspect, optionally, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply further includes an output current sharing control unit. The output current sharing control unit samples the current of the DC-side output inductor Lo of each rectifier power unit, and sums the currents of the DC-side output inductors Lo of each phase full-bridge submodule within the same rectifier power unit to obtain the unit output current of the rectifier power unit; the unit output currents of each rectifier power unit are summed and divided by the number of rectifier power units to obtain a current sharing setpoint; the unit output current of each rectifier power unit is compared with the current sharing setpoint to obtain a current sharing deviation; the current sharing deviation is adjusted by a PI controller to obtain a current sharing compensation amount; the current sharing compensation amount is used to adjust the reference current modulation signal of the corresponding rectifier power unit to obtain a current modulation signal of the DC-side output inductor Lo; the current modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, so that the output current of each rectifier power unit tends to be consistent and parallel circulating current is suppressed.

[0033] In conjunction with the first aspect, optionally, the formula for calculating the current sharing setpoint is:

[0034] ,

[0035] In the formula, The current sharing setpoint for a single rectifier power unit. For the first One rectifier power unit The current of the DC-side output inductor Lo of the full-bridge submodule, This refers to the number of rectifier power units;

[0036] No. The formula for calculating the current sharing deviation of each rectifier power unit is:

[0037] ,

[0038] ,

[0039] In the formula, For the first Current sharing deviation of each rectifier power unit For the first The unit output current of each rectifier power unit;

[0040] No. The formula for calculating the current sharing compensation of each rectifier power unit is:

[0041] ,

[0042] In the formula, For the first Current sharing compensation for each rectifier power unit For PI controller functions;

[0043] No. The formula for calculating the current modulation signal of the DC-side output inductor Lo of each rectifier power unit is as follows:

[0044] ,

[0045] In the formula, For the first The DC-side output inductor Lo of each rectifier power unit is modulated with a current-modulated signal. This is the reference current modulation signal.

[0046] In conjunction with the first aspect, optionally, the low-dropout-ratio multi-unit parallel current source rectifier hydrogen production power supply further includes a ripple suppression unit, which samples the current of the DC-side output inductor Lo of each rectifier power unit and calculates a given ripple current amplitude. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. A phase shift angle is generated by staggered phase allocation with a phase difference of 360° / M between adjacent rectifier power units as the target. M represents the number of rectifier power units, and is further determined based on the phase shift angle. The carrier signal of each rectifier power unit is generated. The carrier signal is compared with the voltage modulation signal or the current modulation signal to generate the corresponding PWM signal. The PWM signal is applied to the controllable switching device in the corresponding rectifier power unit to realize the superposition and cancellation of the ripple current of multiple rectifier power units at the DC positive busbar DC+ and the DC negative busbar DC-.

[0047] In a second aspect, the present invention provides a control method for a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply applicable to any one of the first aspects, comprising:

[0048] The input voltage equalization control unit samples the voltage of the parallel capacitor Cs on the AC side in the A-phase, B-phase, and C-phase input series links of each rectifier power unit. The voltages of the parallel capacitor Cs on the AC side in the same phase of each rectifier power unit are summed and divided by the number of rectifier power units to obtain the equalization setpoint for that phase. The voltage of the parallel capacitor Cs on the AC side in each phase of each rectifier power unit is compared with the equalization setpoint to obtain the equalization deviation for that phase in each rectifier power unit. The equalization deviation for that phase in each rectifier power unit is adjusted by the PR (Pressure Probe) to obtain the equalization compensation amount for that phase in each rectifier power unit. The equalization compensation amount for that phase in each rectifier power unit is used to adjust the reference voltage modulation signal for that phase in each rectifier power unit to obtain the voltage modulation signal of the parallel capacitor Cs on the AC side in each phase of each rectifier power unit. The voltage modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, so that the input voltage distribution of each rectifier power unit in each phase input series link tends to be balanced.

[0049] And / or, the current of the DC-side output inductor Lo of each rectifier power unit is sampled using the output current sharing control unit, and the current of the DC-side output inductor Lo of each phase full-bridge submodule within the same rectifier power unit is summed to obtain the unit output current of the rectifier power unit; the unit output current of each rectifier power unit is summed and divided by the number of rectifier power units to obtain the current sharing setpoint; the unit output current of each rectifier power unit is compared with the current sharing setpoint to obtain the current sharing deviation; the current sharing deviation is adjusted by PI to obtain the current sharing compensation amount; the current sharing compensation amount is used to adjust the reference current modulation signal of the corresponding rectifier power unit to obtain the current modulation signal of the DC-side output inductor Lo; the current modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit to make the output current of each rectifier power unit tend to be consistent and suppress parallel circulating current;

[0050] And / or, using the ripple suppression unit to sample the current of the DC-side output inductor Lo of each rectifier power unit, the amplitude of the given ripple current is calculated. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. A phase shift angle is generated by staggered phase allocation with a phase difference of 360° / M between adjacent rectifier power units as the target. M represents the number of rectifier power units, and is further determined based on the phase shift angle. The carrier signal of each rectifier power unit is generated. The carrier signal is compared with the voltage modulation signal or the current modulation signal to generate the corresponding PWM signal. The PWM signal is applied to the controllable switching device in the corresponding rectifier power unit to realize the superposition and cancellation of the ripple current of multiple rectifier power units at the DC positive busbar DC+ and the DC negative busbar DC-.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] This invention provides a low step-down ratio multi-unit parallel current source rectifier hydrogen production power supply and its control method. The input side is connected in series according to phases to share the voltage, and the output side is connected in parallel to superimpose the current, so that the input voltage of each phase is shared by multiple rectifier power units. From the structural level, the voltage transformation amplitude required by a single unit is reduced, thereby reducing the risks caused by a large step-down ratio.

[0053] Furthermore, the present invention can also achieve input voltage equalization control, so that the input distribution voltage borne by each rectifier power unit in the same phase series link tends to be consistent, thus ensuring the stable operation of the input side series link.

[0054] Furthermore, the present invention can also achieve output current sharing control, so that the output current of each rectifier power unit tends to be consistent, suppress parallel circulating current and realize the capacity superposition of parallel system, thereby improving the stability and scalability of parallel system.

[0055] Furthermore, the present invention significantly reduces DC output current ripple through interleaved modulation with a phase difference of 360° / M, thereby improving the power supply stability and system reliability of low-voltage, high-current electrolytic hydrogen production loads. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0057] Figure 1 This is a flowchart of a control method for a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention;

[0058] Figure 2 This is a topology diagram of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention;

[0059] Figure 3 A diagram of the power supply topology of a traditional multi-machine parallel current source rectifier.

[0060] Figure 4This is a block diagram of the input voltage equalization control of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention;

[0061] Figure 5 This is a block diagram of the output current sharing control of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention.

[0062] Figure 6 This is a block diagram of the multi-module interleaved control of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention;

[0063] Figure 7 A schematic diagram of the voltage of the parallel capacitor Cs on the AC side of a traditional multi-machine parallel current source rectifier.

[0064] Figure 8 This is a schematic diagram of the voltage of the parallel capacitor Cs on the AC side of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention.

[0065] Figure 9 This is a schematic diagram of the current waveform of the DC-side output inductor Lo of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention.

[0066] Figure 10 This is a schematic diagram of the output current waveform of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply without interleaved control, according to an embodiment of the present invention.

[0067] Figure 11 This is a schematic diagram of the output current waveform of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply using interleaved control, according to an embodiment of the present invention. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0070] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0071] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0073] Example 1

[0074] This invention provides a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply, such as... Figure 2 As shown, it includes:

[0075] The three-phase AC input busbars include phase A busbar, phase B busbar, phase C busbar, and neutral busbar N;

[0076] DC output busbars, including DC positive busbar DC+ and DC negative busbar DC-;

[0077] At least three rectifier power units are provided, each connected in series on the AC side between phase A busbar and neutral busbar N, phase B busbar and neutral busbar N, and phase C busbar and neutral busbar N, respectively, so that phase A, phase B, and phase C form an input series link composed of at least three rectifier power units; the positive DC output terminal and negative DC output terminal of each rectifier power unit are connected in parallel to the positive DC busbar DC+ and the negative DC busbar DC-, respectively.

[0078] In the above scheme, the input side is connected in series by phase to share the voltage, and the output side is connected in parallel to superimpose the current, so that the input voltage of each phase is shared by multiple rectifier power units. This reduces the voltage transformation amplitude that a single unit needs to bear from a structural perspective, thereby reducing the risks brought about by a large step-down ratio.

[0079] In one specific embodiment of the present invention, each of the rectifier power units includes at least three mutually independent A-phase full-bridge submodules, B-phase full-bridge submodules, and C-phase full-bridge submodules. The A-phase full-bridge submodules, B-phase full-bridge submodules, and C-phase full-bridge submodules have the same structure and each includes:

[0080] The circuit consists of a first controllable switch device S1, a second controllable switch device S2, a third controllable switch device S3, and a fourth controllable switch device S4. The first controllable switch device S1 and the third controllable switch device S3 are connected in series to form a first bridge arm, the second controllable switch device S2 and the fourth controllable switch device S4 are connected in series to form a second bridge arm, and the first bridge arm and the second bridge arm are connected in parallel to form a full bridge circuit.

[0081] The AC-side series inductor Ls is connected in series between the corresponding phase busbar and the AC input terminal of the corresponding full-bridge circuit to limit the rate of change of AC current, improve the current waveform and reduce harmonics.

[0082] A parallel capacitor Cs on the AC side is set between the corresponding phase busbar and the corresponding neutral busbar N to form a voltage sampling and voltage support node, and to serve as one of the objects of input distribution voltage equalization control.

[0083] The DC-side output inductor Lo is connected in series on the DC output branch of the corresponding full-bridge submodule to form current source characteristics, limit DC-side current ripple, and achieve current controllability.

[0084] The above scheme specifies the exact structure of the rectifier power unit, which facilitates later implementation.

[0085] In one specific embodiment of the present invention, the DC output branches in each rectifier power unit are independent of each other. After the DC output branches are combined, they form the DC positive output terminal and the DC negative output terminal of the rectifier power unit. The DC positive output terminal is connected to the DC positive busbar DC+, and the DC negative output terminal is connected to the DC negative busbar DC-. That is, the DC positive / negative output terminals of each rectifier power unit are then connected in parallel to the DC positive busbar DC+ and the DC negative busbar DC-.

[0086] In the above scheme, the DC output terminals of each rectifier power unit are connected in parallel to the DC+ and DC− busbars, so that the output current of multiple units is combined and superimposed at the busbars to meet the low-voltage and high-current requirements of the hydrogen production load, while also having good capacity scalability.

[0087] In one specific embodiment of the present invention, the A-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, ..., and the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming the input series link of the A-phase.

[0088] The B-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, ..., and the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming the input series link of the B-phase.

[0089] The C-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, and so on, until the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming a C-phase input series link.

[0090] In the above scheme, the input voltage of each phase is shared by multiple rectifier power units through this connection method, thereby reducing the voltage transformation amplitude required by a single rectifier power unit and reducing the device stress, insufficient control margin and abnormal operation risk caused by the large step-down ratio of the current source rectifier in low-voltage, high-current scenarios.

[0091] In one specific embodiment of the present invention, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply further includes an input voltage equalization control unit. The input terminal of the input voltage equalization control unit samples the voltage of the parallel capacitor Cs on the AC side of each rectifier power unit in the A-phase, B-phase, and C-phase input series links. The voltages of the parallel capacitor Cs on the AC side of the same phase in each rectifier power unit are summed and divided by the number of rectifier power units to obtain the equalization setpoint for that phase. The voltage of the parallel capacitor Cs on the AC side of that phase in each rectifier power unit is then compared with the equalization setpoint for that phase. The voltage equalization deviation of each phase in each rectifier power unit is compared and obtained. The voltage equalization deviation of each phase in each rectifier power unit is adjusted by PR to obtain the voltage equalization compensation amount of each phase in each rectifier power unit. The voltage equalization compensation amount of each phase in each rectifier power unit is used to adjust the reference voltage modulation signal of each phase in each rectifier power unit to obtain the voltage modulation signal of the AC side parallel capacitor Cs of each phase in each rectifier power unit. The voltage modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit so that the input distribution voltage of each rectifier power unit in each phase input series link tends to be balanced.

[0092] The above scheme can achieve input voltage equalization control, so that the input distribution voltage borne by each rectifier power unit in the same phase series link tends to be consistent, ensuring the stable operation of the input side series link.

[0093] In one specific embodiment of the present invention, The formula for calculating the equalization pressure setpoint of the phase is:

[0094] ,

[0095] In the formula, for The given value for the equalization pressure of the phase; For the first One rectifier power unit The voltage of the parallel capacitor Cs on the AC side of the phase, ; This refers to the number of rectifier power units;

[0096] No. One rectifier power unit The formula for calculating the phase equalization deviation is:

[0097] ,

[0098] In the formula, For the first One rectifier power unit Phase pressure uniformity deviation;

[0099] No. One rectifier power unit The formula for calculating the equalization compensation of the phase is:

[0100] ,

[0101] In the formula, For the first One rectifier power unit Phase equalization compensation amount For PR controller functions;

[0102] No. One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase is:

[0103] ,

[0104] In the formula, For the first One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase. for The reference voltage modulation signal for the phase.

[0105] In the specific implementation process, such as Figure 4 As shown, the first The voltage modulation signals of the parallel capacitor Cs on the AC side of each phase of the rectifier power unit are summed to obtain the first... Voltage modulation signal of each rectifier power unit , The calculation formula is:

[0106] ,

[0107] Will After being converted into a PWM signal, it acts on each controllable switching device in the corresponding rectifier power unit.

[0108] In one specific embodiment of the present invention, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply further includes an output current sharing control unit. The output current sharing control unit samples the current of the DC-side output inductor Lo of each rectifier power unit, and sums the currents of the DC-side output inductors Lo of each phase full-bridge submodule within the same rectifier power unit to obtain the unit output current of the rectifier power unit. The unit output currents of each rectifier power unit are summed and divided by the number of rectifier power units to obtain a current sharing setpoint. The unit output current of each rectifier power unit is compared with the current sharing setpoint to obtain a current sharing deviation. The current sharing deviation is adjusted by a PI controller to obtain a current sharing compensation amount. The current sharing compensation amount is used to adjust the reference current modulation signal of the corresponding rectifier power unit to obtain a current modulation signal of the DC-side output inductor Lo. The current modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, so that the output current of each rectifier power unit tends to be consistent and parallel circulating current is suppressed.

[0109] The above scheme can achieve output current sharing control, making the output current of each rectifier power unit tend to be consistent, suppressing parallel circulating current and realizing the capacity superposition of parallel system, thereby improving the stability and scalability of parallel system.

[0110] In one specific embodiment of the present invention, the formula for calculating the current sharing setpoint is as follows:

[0111] ,

[0112] In the formula, The current sharing setpoint for a single rectifier power unit. For the first One rectifier power unit The current of the DC-side output inductor Lo of the full-bridge submodule, This refers to the number of rectifier power units;

[0113] No. The formula for calculating the current sharing deviation of each rectifier power unit is:

[0114] ,

[0115] ,

[0116] In the formula, For the first Current sharing deviation of each rectifier power unit For the first The unit output current of each rectifier power unit;

[0117] No. The formula for calculating the current sharing compensation of each rectifier power unit is:

[0118] ,

[0119] In the formula, For the first Current sharing compensation for each rectifier power unit For PI controller functions;

[0120] No. The formula for calculating the current modulation signal of the DC-side output inductor Lo of each rectifier power unit is as follows:

[0121] ,

[0122] In the formula, For the first The DC-side output inductor Lo of each rectifier power unit is modulated with a current-modulated signal. This is the reference current modulation signal.

[0123] In the specific implementation process, it will also include It is converted into a PWM signal, which is applied to each controllable switching device in the corresponding rectifier power unit.

[0124] In one specific embodiment of the present invention, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply further includes a ripple suppression unit. The carrier waves of different rectifier power units are interleaved according to the number of rectifier power units, with a phase difference of 360° / M between adjacent rectifier power units, where M is the number of rectifier power units. The goal is to superimpose and cancel the output current ripples of multiple rectifier power units at the DC positive busbar (DC+) and the DC negative busbar (DC-). Switching drive signals for each rectifier power unit are generated or adjusted to drive the first controllable switching device S1, the second controllable switching device S2, the third controllable switching device S3, and the fourth controllable switching device S4. Specifically, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply further includes a ripple suppression unit. This ripple suppression unit samples the current of the DC-side output inductor Lo of each rectifier power unit and calculates the given ripple current amplitude. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. Phase shift angle is generated by staggered phase allocation. Based on the phase shift angle Carrier signals are generated for each rectifier power unit. The carrier signals are compared with voltage modulation signals or current modulation signals to generate corresponding PWM signals, which are applied to the controllable switching devices in the corresponding rectifier power unit. The phase difference between adjacent rectifier power units is 360° / M, where M is the number of rectifier power units. This enables the ripple current of multiple rectifier power units to be superimposed and canceled at the DC positive busbar DC+ and the DC negative busbar DC-.

[0125] In the above scheme, the DC output current ripple is significantly reduced by interleaved modulation with a phase difference of 360° / M, thereby improving the power supply stability and system reliability of the low-voltage, high-current electrolytic hydrogen production load.

[0126] The following is combined with Figures 1-11 The present invention provides a detailed description of the low step-down ratio multi-machine parallel current source rectifier hydrogen production power supply and its working principle in a specific embodiment.

[0127] This embodiment provides a low-dropout-ratio multi-unit parallel current source rectifier hydrogen production power supply. It employs a structure of series voltage division on the input side and parallel superimposed current on the output side to reduce the risk of a large dropout ratio in a single unit. Based on this, it implements input voltage equalization control, output current equalization control, and interleaved modulation to reduce output current ripple. For example... Figure 2 As shown, the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply in this embodiment includes: a three-phase AC input busbar, a DC output busbar, and three rectifier power units, denoted as rectifier power unit 1, rectifier power unit 2, and rectifier power unit 3, respectively. The three-phase AC input busbar includes phase A busbar, phase B busbar, phase C busbar, and neutral busbar N; the DC output busbar includes a positive DC busbar DC+ and a negative DC busbar DC-, used to connect a low-voltage, high-current electrolysis hydrogen production load.

[0128] Each rectifier power unit is connected in series on the AC side between phase A busbar and neutral busbar N, phase B busbar and neutral busbar N, and phase C busbar and neutral busbar N, respectively. This forms an input series link consisting of three rectifier power units for phases A, B, and C, achieving series connection on the input side. In this way, the input voltage of each phase is shared by multiple rectifier power units, thereby reducing the voltage transformation amplitude required by a single rectifier power unit. This reduces the device stress, insufficient control margin, and abnormal operation risks caused by the large step-down ratio of current source rectifiers in low-voltage, high-current scenarios.

[0129] The DC output terminals of each rectifier power unit are connected in parallel to the DC positive busbar (DC+) and the DC negative busbar (DC-), realizing parallel connection on the output side. This allows the output currents of multiple units to converge and superimpose at the busbar, meeting the low-voltage, high-current requirements of the hydrogen production load, while also providing good capacity scalability.

[0130] likeFigure 2 As shown, each rectifier power unit includes at least three independent full-bridge sub-modules, namely the A-phase full-bridge sub-module, the B-phase full-bridge sub-module, and the C-phase full-bridge sub-module. Each phase full-bridge submodule includes at least: four controllable switching devices, defined as first controllable switching device S1, second controllable switching device S2, third controllable switching device S3, and second controllable switching device S4, which together form a full bridge (two bridge arms connected in parallel); an AC-side series inductor Ls, connected in series between the corresponding phase busbar and the AC input terminal of the full bridge, used to limit the rate of change of AC current, improve the current waveform, and reduce harmonics; an AC-side parallel capacitor Cs, connected in parallel between the corresponding phase busbar and the corresponding neutral busbar N, used to form a voltage sampling and voltage support node, and as one of the objects of input distribution voltage equalization control; a DC-side output inductor Lo, connected in series on the DC output branch of the corresponding full-bridge submodule, used to form current source characteristics, limit DC-side current ripple, and achieve current controllability; and independent DC positive and DC negative output terminals. Within each rectifier power unit, the DC output branches of the A-phase full-bridge submodule, B-phase full-bridge submodule, and C-phase full-bridge submodule are independent of each other, and are combined into DC outputs after passing through their respective output inductors Lo, forming the unit's positive DC output terminal and negative DC output terminal. The positive / negative DC output terminals of each rectifier power unit are then connected in parallel to the positive DC bus DC+ and the negative DC bus DC-.

[0131] To facilitate understanding of the mechanism for reducing the risk of large voltage drop ratios proposed in this invention, a comparative explanation of the topology of a traditional multi-machine parallel current source rectifier hydrogen production power supply is provided. For example... Figure 3 As shown, the traditional scheme also includes multiple rectifier power units, but their connection method is as follows: the AC side of each rectifier power unit is connected in parallel to the three-phase AC input busbar (phase A busbar, phase B busbar, phase C busbar, and neutral busbar N), and the DC side of each rectifier power unit is also connected in parallel to the DC output busbar (DC positive busbar DC+ and DC negative busbar DC-). That is, the traditional scheme adopts a parallel structure on both the AC and DC sides. In this traditional parallel topology, since the AC side of each rectifier power unit directly bears the grid-side phase voltage (or phase-N voltage) input, while the hydrogen production load side is a low-voltage, high-current DC output, a single rectifier power unit needs to independently complete the energy conversion from a higher AC input to a lower-voltage DC output, objectively forming a large step-down ratio requirement for a single unit. This large step-down ratio requirement usually leads to:

[0132] (a) The design pressure on key components such as power devices and inductors of a single rectifier power unit in terms of voltage / current stress, modulation margin and protection coordination has increased;

[0133] (b) Under low-voltage, high-current output conditions, the operating point of a single unit is more likely to be in the region with small modulation or control margin, and the system becomes more sensitive to parameter deviations and operating condition fluctuations.

[0134] (c) When multiple machines are connected in parallel, the inconsistent parameters of each rectifier power unit (such as filter parameters, device voltage drop, drive delay, etc.) can easily lead to current distribution deviation and circulating current risk in the parallel system, which in turn affects the output current quality and system reliability.

[0135] and Figure 3 Compared with the conventional solution shown, the present invention is as follows: Figure 2 As shown, by connecting the input phases in series to share the voltage and by connecting the output phases in parallel to superimpose the current, the input voltage of each phase is shared by multiple rectifier power units. This reduces the voltage transformation amplitude that a single unit needs to handle from a structural perspective, thereby reducing the risks associated with a large step-down ratio. Furthermore, by combining this with subsequent input voltage equalization, output current equalization, and interleaved ripple suppression strategies, the system stability and output current quality are further improved.

[0136] To ensure stable operation of the input series link, the input distribution voltage borne by each rectifier power unit in the same phase input series link needs to be consistent. This embodiment adopts voltage equalization control based on the voltage of the AC-side parallel capacitor Cs.

[0137] like Figure 4 As shown, the input voltage equalization control is performed phase-by-phase. For each phase { }, for the first Each rectifier power unit samples the voltage of its AC-side parallel capacitor. , ( ).

[0138] 1) Generation of equal pressure reference:

[0139] According to formula (1), for the same phase Voltage of all AC-side parallel capacitors Cs The average value is calculated to obtain the setpoint for the phase equal pressure. :

[0140] (1);

[0141] When M=3, it is the sum of the in-phase capacitor voltages of the three rectifier power units divided by 3.

[0142] 2) Calculation of equal pressure deviation and adjustment of PR:

[0143] According to formula (2), the voltage equalization deviation is calculated for each rectifier power unit. :

[0144] (2);

[0145] In the formula, For the first One rectifier power unit Phase pressure uniformity deviation;

[0146] The deviation is input to the PR controller to obtain the equalization compensation amount. , No. One rectifier power unit The formula for calculating the equalization compensation of the phase is:

[0147] (3);

[0148] In the formula, For the first One rectifier power unit Phase equalization compensation amount For PR controller functions;

[0149] 3) Target of compensation:

[0150] The voltage equalization deviation of each phase in each rectifier power unit is adjusted by PR to obtain the voltage equalization compensation amount for that phase in each rectifier power unit. This compensation amount is then used to adjust the reference voltage modulation signal for that phase in each rectifier power unit, resulting in the voltage modulation signal of the AC-side parallel capacitor Cs for that phase in each rectifier power unit. This automatically adjusts and balances the equivalent voltage distribution in the input series link of that phase of the rectifier power unit. Through this voltage equalization strategy, the voltage distribution of each unit in the series link can automatically recover to equilibrium when parameters are inconsistent, temperature rise drifts, or operating conditions change, reducing the risk of overvoltage in the series link. Specifically: the first... One rectifier power unit The phase voltage modulation signal is:

[0151] ,

[0152] In the formula, For the first One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase. for The reference voltage modulation signal for the phase.

[0153] In the specific implementation process, such as Figure 4 As shown, the first The voltage modulation signals of the parallel capacitor Cs on the AC side of each phase of the rectifier power unit are summed to obtain the first... Voltage modulation signal of each rectifier power unit , The calculation formula is:

[0154] ,

[0155] Will After being converted into PWM signals, they are applied to the controllable switching devices (S1-S4) in the corresponding rectifier power unit.

[0156] To suppress parallel circulating current and achieve capacity superposition in the parallel system, the output current of each rectifier power unit needs to be made consistent. This embodiment employs current sharing control based on the output inductor Lo. Figure 5 As shown, for the first The output inductor current of each of the three-phase output branches inside the rectifier power unit is sampled respectively:

[0157] 1) Generation of the current sharing reference (summation / division by M):

[0158] The average output current of all rectifier power units is used to obtain the current sharing setpoint. :

[0159] (4);

[0160] When M=3, it is the sum of the output currents of the three rectifier power units divided by 3.

[0161] 2) Calculation of flow equalization deviation and PI adjustment:

[0162] Calculate the current sharing deviation for each rectifier power unit. :

[0163] (5);

[0164] In the formula, For the first Current sharing deviation of each rectifier power unit For the first The unit output current of each rectifier power unit;

[0165] The current sharing deviation is input into the PI controller to obtain the first... Current sharing compensation of each rectifier power unit :

[0166] (6);

[0167] In the formula, For the first Current sharing compensation for each rectifier power unit For PI controller functions;

[0168] 3) Target of compensation:

[0169] The first Current sharing compensation of each rectifier power unit Acting on the The reference current modulation signal of each rectifier power unit is used to obtain the current modulation signal, so that the output current of each unit tends to be consistent, while suppressing parallel circulating current and improving the stability and scalability of the parallel system.

[0170] No. The formula for calculating the current modulation signal of the DC-side output inductor Lo of each rectifier power unit is as follows:

[0171] ,

[0172] In the formula, For the first The DC-side output inductor Lo of each rectifier power unit is modulated with a current-modulated signal. This is the reference current modulation signal.

[0173] Again PWM modulation is performed to generate PWM signals that regulate the output current of each rectifier power unit, which are then applied to the controllable switching devices in the corresponding rectifier power unit.

[0174] Under the condition of multiple rectifier power units connected in parallel, even if the output inductance Lo of each rectifier power unit can reduce local ripple, the bus current ripple after multiple units are connected in parallel may still affect the working stability of the electrolytic hydrogen production load. This embodiment further adopts an interleaved modulation / phase staggered strategy to reduce output ripple.

[0175] like Figure 6 As shown, the carrier phase shift angle of each unit is controlled by controlling the ripple amplitude. The current of the DC-side output inductor Lo of each rectifier power unit is sampled, and the given ripple current amplitude is calculated. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. Phase shift angle is generated by staggered phase allocation. Based on the phase shift angle Carrier signals are generated for each rectifier power unit. These carrier signals are compared with voltage modulation or current modulation signals to generate corresponding PWM signals, which are then applied to the controllable switching devices within the corresponding rectifier power unit. The phase difference between adjacent rectifier power units is 360° / M, where M is the number of rectifier power units. This allows the ripple currents of multiple rectifier power units to be superimposed and canceled at the DC positive busbar (DC+) and the DC negative busbar (DC-). When M=3, the phase of each rectifier power unit can be sequentially set to 0. ∘ 120 ∘ 240 ∘After interleaving, the ripple components of the output current of each rectifier power unit are superimposed and canceled at the DC bus, resulting in an increase in the ripple equivalent frequency and a decrease in the ripple amplitude, thereby achieving the purpose of reducing output current ripple and improving the quality of hydrogen production load current.

[0176] Based on the above design, this embodiment achieves phase voltage sharing through input-side series connection, reducing the requirement for a large step-down ratio in a single unit and mitigating risk; it improves the stability of voltage distribution in the series link through input voltage equalization control based on the voltage of the parallel capacitor Cs on the AC side; it achieves inter-unit current equalization and suppresses circulating current through output current equalization control based on the current of the output inductor Lo on the DC side; and it utilizes a phase difference of 360°. ∘ The interleaved modulation of / N significantly reduces DC output current ripple, thereby improving the power supply stability and system reliability of low-voltage, high-current electrolytic hydrogen production loads.

[0177] Figure 7 A schematic diagram of the voltage of the parallel capacitor Cs on the AC side of a traditional multi-machine parallel current source rectifier. Figure 8 This is a schematic diagram of the AC side parallel capacitor Cs of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention. (Comparison) Figure 8 and Figure 7 It can be seen that, under the same input voltage, the input capacitor voltage of the present invention is smaller, the device stress is lower, and the input capacitor voltage is balanced.

[0178] Figure 9 This is a schematic diagram of the current waveform of the DC-side output inductor Lo of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to an embodiment of the present invention. Based on Figure 9 It can be seen that the present invention can achieve output current balancing.

[0179] Figure 10 This is a schematic diagram of the output current waveform of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply without interleaved control, according to an embodiment of the present invention. Figure 11 This is a schematic diagram of the output current waveform of a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply using interleaved control, according to an embodiment of the present invention. Figure 10 and Figure 11 In the graph, the horizontal axis represents time, and the vertical axis represents the output current. (Comparison) Figure 10 and Figure 11 It can be observed that the output current ripple of this invention is smaller under interleaved parallel control.

[0180] Example 2

[0181] This invention provides a control method for a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply applicable to any one of Embodiment 1, comprising:

[0182] The input voltage equalization control unit samples the voltage of the parallel capacitor Cs on the AC side in the A-phase, B-phase, and C-phase input series links of each rectifier power unit. The voltages of the parallel capacitor Cs on the AC side in the same phase of each rectifier power unit are summed and divided by the number of rectifier power units to obtain the equalization setpoint for that phase. The voltage of the parallel capacitor Cs on the AC side in each phase of each rectifier power unit is compared with the equalization setpoint to obtain the equalization deviation for that phase in each rectifier power unit. The equalization deviation for that phase in each rectifier power unit is adjusted by the PR (Pressure Probe) to obtain the equalization compensation amount for that phase in each rectifier power unit. The equalization compensation amount for that phase in each rectifier power unit is used to adjust the reference voltage modulation signal for that phase in each rectifier power unit to obtain the voltage modulation signal of the parallel capacitor Cs on the AC side in each phase of each rectifier power unit. The voltage modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, so that the input voltage distribution of each rectifier power unit in each phase input series link tends to be balanced.

[0183] And / or, the current of the DC-side output inductor Lo of each rectifier power unit is sampled using the output current sharing control unit, and the current of the DC-side output inductor Lo of each phase full-bridge submodule within the same rectifier power unit is summed to obtain the unit output current of the rectifier power unit; the unit output current of each rectifier power unit is summed and divided by the number of rectifier power units to obtain the current sharing setpoint; the unit output current of each rectifier power unit is compared with the current sharing setpoint to obtain the current sharing deviation; the current sharing deviation is adjusted by PI to obtain the current sharing compensation amount; the current sharing compensation amount is used to adjust the reference current modulation signal of the corresponding rectifier power unit to obtain the current modulation signal of the DC-side output inductor Lo; the current modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit to make the output current of each rectifier power unit tend to be consistent and suppress parallel circulating current;

[0184] And / or, using the ripple suppression unit to sample the current of the DC-side output inductor Lo of each rectifier power unit, the amplitude of the given ripple current is calculated. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. A phase shift angle is generated by staggered phase allocation with a phase difference of 360° / M between adjacent rectifier power units as the target. M represents the number of rectifier power units, and is further determined based on the phase shift angle. The carrier signal of each rectifier power unit is generated. The carrier signal is compared with the voltage modulation signal or the current modulation signal to generate the corresponding PWM signal. The PWM signal is applied to the controllable switching device in the corresponding rectifier power unit to realize the superposition and cancellation of the ripple current of multiple rectifier power units at the DC positive busbar DC+ and the DC negative busbar DC-.

[0185] like Figure 1 As shown, in specific implementation, the control method for the low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply applicable to any one of Embodiment 1 specifically includes:

[0186] By adopting a system topology with series connection on the input side and parallel connection on the output side, the voltage transformation amplitude undertaken by a single unit is reduced, thereby reducing the requirement for a large step-down ratio under low-voltage, high-current conditions.

[0187] The input voltage equalization control is set up to perform closed-loop regulation of the input distribution voltage of each rectifier power unit in series, so as to achieve voltage balance among each rectifier power unit.

[0188] The output current sharing control is set to perform closed-loop regulation of the output current of each parallel rectifier power unit, so as to achieve equal current sharing of each rectifier power unit and suppress circulating current.

[0189] An optimized modulation strategy is adopted under the constraints of voltage and current equalization control to reduce output current ripple and improve the output current quality during low-voltage, high-current operation.

[0190] Based on the above solution, the following effects can be achieved:

[0191] (1) The input side is connected in series according to phase to share the voltage, and the output side is connected in parallel to superimpose the current, so that the input voltage of each phase is shared by multiple rectifier power units. This reduces the voltage transformation amplitude required by a single unit from the structural level, thereby reducing the risk brought about by a large step-down ratio.

[0192] (2) It can realize input voltage equalization control, so that the input distribution voltage undertaken by each rectifier power unit in the same phase series link tends to be consistent, and ensures the stable operation of the input side series link.

[0193] (3) It can realize output current sharing control, so that the output current of each rectifier power unit tends to be consistent, suppress parallel circulating current and realize the capacity superposition of parallel system, and improve the stability and scalability of parallel system.

[0194] (4) Through a phase difference of 360 ∘ The interleaved modulation of / M significantly reduces DC output current ripple, thereby improving the power supply stability and system reliability of low-voltage, high-current electrolytic hydrogen production loads.

[0195] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0196] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A low-dropout-ratio multi-machine parallel current source type rectifier hydrogen production power supply, characterized in that, include: The three-phase AC input busbars include phase A busbar, phase B busbar, phase C busbar, and neutral busbar N; DC output busbars, including DC positive busbar DC+ and DC negative busbar DC-; At least three rectifier power units are provided, each connected in series on the AC side between phase A busbar and neutral busbar N, phase B busbar and neutral busbar N, and phase C busbar and neutral busbar N, respectively, so that phase A, phase B, and phase C form an input series link composed of at least three rectifier power units; the positive DC output terminal and negative DC output terminal of each rectifier power unit are connected in parallel to the positive DC busbar DC+ and the negative DC busbar DC-, respectively.

2. The low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 1, characterized in that: Each of the aforementioned rectifier power units includes at least three independent A-phase full-bridge submodules, B-phase full-bridge submodules, and C-phase full-bridge submodules. The A-phase full-bridge submodules, B-phase full-bridge submodules, and C-phase full-bridge submodules have the same structure and each includes: The circuit consists of a first controllable switch device S1, a second controllable switch device S2, a third controllable switch device S3, and a fourth controllable switch device S4. The first controllable switch device S1 and the third controllable switch device S3 are connected in series to form a first bridge arm, the second controllable switch device S2 and the fourth controllable switch device S4 are connected in series to form a second bridge arm, and the first bridge arm and the second bridge arm are connected in parallel to form a full bridge circuit. The AC side series inductor Ls is connected in series between the corresponding phase busbar and the AC input terminal of the corresponding full-bridge circuit; A parallel capacitor Cs is connected on the AC side, and is set in parallel between the corresponding phase busbar and the corresponding neutral busbar N. The DC-side output inductor Lo is connected in series on the DC output branch of the corresponding full-bridge submodule.

3. The low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 2, characterized in that: Each of the rectifier power units has an independent DC output branch. After the DC output branches are combined, they form the positive DC output terminal and the negative DC output terminal of the rectifier power unit. The positive DC output terminal is connected to the positive DC bus (DC+), and the negative DC output terminal is connected to the negative DC bus (DC-).

4. A low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 2, characterized in that: The A-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, ..., and the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming the input series link of the A-phase. The B-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, ..., and the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming the input series link of the B-phase. The C-phase busbar is connected to the positive AC input of the first rectifier power unit, the negative AC input of the first rectifier power unit is connected to the positive AC input of the second rectifier power unit, and so on, until the negative AC input of the last rectifier power unit is connected to the neutral busbar N, forming a C-phase input series link.

5. A low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 4, characterized in that: The low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply also includes an input voltage equalization control unit. This control unit samples the voltage of the parallel capacitor Cs on the AC side of each rectifier power unit in the A-phase, B-phase, and C-phase input series links. It sums the voltages of the parallel capacitor Cs on the AC side of the same phase in each rectifier power unit and divides this sum by the number of rectifier power units to obtain the equalization setpoint for that phase. Finally, it compares the voltage of the parallel capacitor Cs on the AC side of that phase in each rectifier power unit with the equalization setpoint for that phase to obtain the voltage of each rectifier power unit. The voltage equalization deviation of the phase in each rectifier power unit is determined; the voltage equalization deviation of the phase in each rectifier power unit is adjusted by PR to obtain the voltage equalization compensation amount of the phase in each rectifier power unit; the voltage equalization compensation amount of the phase in each rectifier power unit is used to adjust the reference voltage modulation signal of the phase in each rectifier power unit to obtain the voltage modulation signal of the AC side parallel capacitor Cs of the phase in each rectifier power unit; the voltage modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, so that the input distribution voltage of each rectifier power unit in the input series link of each phase tends to be balanced.

6. A low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 5, characterized in that: The formula for calculating the equalization pressure setpoint of the phase is: ， In the formula, for The given value for the equalization pressure of the phase; For the first One rectifier power unit The voltage of the parallel capacitor Cs on the AC side of the phase, ; This refers to the number of rectifier power units; No. One rectifier power unit The formula for calculating the phase equalization deviation is: ， In the formula, For the first One rectifier power unit Phase pressure uniformity deviation; No. One rectifier power unit The formula for calculating the equalization compensation of the phase is: ， In the formula, For the first One rectifier power unit Phase equalization compensation amount For PR controller functions; No. One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase is: ， In the formula, For the first One rectifier power unit The voltage modulation signal of the parallel capacitor Cs on the AC side of the phase. for The reference voltage modulation signal for the phase.

7. A low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 5, characterized in that: The low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply also includes an output current sharing control unit. This control unit samples the current of the DC-side output inductor Lo of each rectifier power unit, and sums the currents of the DC-side output inductors Lo of each phase full-bridge submodule within the same rectifier power unit to obtain the unit output current of that rectifier power unit. The unit output currents of each rectifier power unit are summed and divided by the number of rectifier power units to obtain a current sharing setpoint. The unit output current of each rectifier power unit is compared with the current sharing setpoint to obtain a current sharing deviation. The current sharing deviation is adjusted via a PI controller to obtain a current sharing compensation amount. This compensation amount is used to adjust the reference current modulation signal of the corresponding rectifier power unit to obtain a current modulation signal for the DC-side output inductor Lo. The current modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, making the output current of each rectifier power unit more consistent and suppressing parallel circulating current.

8. A low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 7, characterized in that: The formula for calculating the setpoint for the current sharing is: ， In the formula, The current sharing setpoint for a single rectifier power unit. For the first One rectifier power unit The current of the DC-side output inductor Lo of the full-bridge submodule, This refers to the number of rectifier power units; No. The formula for calculating the current sharing deviation of each rectifier power unit is: ， ， In the formula, For the first Current sharing deviation of each rectifier power unit For the first The unit output current of each rectifier power unit; No. The formula for calculating the current sharing compensation of each rectifier power unit is: ， In the formula, For the first Current sharing compensation for each rectifier power unit For PI controller functions; No. The formula for calculating the current modulation signal of the DC-side output inductor Lo of each rectifier power unit is as follows: ， In the formula, For the first The DC-side output inductor Lo of each rectifier power unit is modulated with a current-modulated signal. This is the reference current modulation signal.

9. A low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply according to claim 7, characterized in that: The low-dropout-ratio multi-unit parallel current source rectifier hydrogen production power supply also includes a ripple suppression unit. This ripple suppression unit samples the current of the DC-side output inductor Lo of each rectifier power unit and calculates the amplitude of a given ripple current. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. A phase shift angle is generated by staggered phase allocation with a phase difference of 360° / M between adjacent rectifier power units as the target. M represents the number of rectifier power units, and is further determined based on the phase shift angle. The carrier signal of each rectifier power unit is generated. The carrier signal is compared with the voltage modulation signal or the current modulation signal to generate the corresponding PWM signal. The PWM signal is applied to the controllable switching device in the corresponding rectifier power unit to realize the superposition and cancellation of the ripple current of multiple rectifier power units at the DC positive busbar DC+ and the DC negative busbar DC-.

10. A control method for a low-dropout-ratio multi-machine parallel current source rectifier hydrogen production power supply applicable to any one of claims 1-9, characterized in that, include: The input voltage equalization control unit samples the voltage of the parallel capacitor Cs on the AC side in the A-phase, B-phase, and C-phase input series links of each rectifier power unit. The voltages of the parallel capacitor Cs on the AC side in the same phase of each rectifier power unit are summed and divided by the number of rectifier power units to obtain the equalization setpoint for that phase. The voltage of the parallel capacitor Cs on the AC side in each phase of each rectifier power unit is compared with the equalization setpoint to obtain the equalization deviation for that phase in each rectifier power unit. The equalization deviation for that phase in each rectifier power unit is adjusted by the PR (Pressure Probe) to obtain the equalization compensation amount for that phase in each rectifier power unit. The equalization compensation amount for that phase in each rectifier power unit is used to adjust the reference voltage modulation signal for that phase in each rectifier power unit to obtain the voltage modulation signal of the parallel capacitor Cs on the AC side in each phase of each rectifier power unit. The voltage modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit, so that the input voltage distribution of each rectifier power unit in each phase input series link tends to be balanced. And / or, the current of the DC-side output inductor Lo of each rectifier power unit is sampled using the output current sharing control unit, and the current of the DC-side output inductor Lo of each phase full-bridge submodule within the same rectifier power unit is summed to obtain the unit output current of the rectifier power unit; the unit output current of each rectifier power unit is summed and divided by the number of rectifier power units to obtain the current sharing setpoint; the unit output current of each rectifier power unit is compared with the current sharing setpoint to obtain the current sharing deviation; the current sharing deviation is adjusted by PI to obtain the current sharing compensation amount; the current sharing compensation amount is used to adjust the reference current modulation signal of the corresponding rectifier power unit to obtain the current modulation signal of the DC-side output inductor Lo; the current modulation signal is processed into a PWM signal and applied to each controllable switching device in the rectifier power unit to make the output current of each rectifier power unit tend to be consistent and suppress parallel circulating current; And / or, using the ripple suppression unit to sample the current of the DC-side output inductor Lo of each rectifier power unit, the amplitude of the given ripple current is calculated. The actual ripple current amplitude in the current of the DC-side output inductor Lo The difference is used to generate a carrier phase-shift signal after PI regulation. A phase shift angle is generated by staggered phase allocation with a phase difference of 360° / M between adjacent rectifier power units as the target. M represents the number of rectifier power units, and is further determined based on the phase shift angle. The carrier signal of each rectifier power unit is generated. The carrier signal is compared with the voltage modulation signal or the current modulation signal to generate the corresponding PWM signal. The PWM signal is applied to the controllable switching device in the corresponding rectifier power unit to realize the superposition and cancellation of the ripple current of multiple rectifier power units at the DC positive busbar DC+ and the DC negative busbar DC-.

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