Power supply device of new energy hydrogen production system, new energy hydrogen production system and control method

Abstract

The embodiments of the present application provide a power supply device, a new energy hydrogen production system and a control method, a three-phase buck rectifier circuit, a DC conversion circuit and a controller for a new energy hydrogen production system. The three-phase rectifier circuit adopts a three-phase buck rectifier structure, and adopts an SVPWM modulation method to control the three-phase rectifier circuit. The SVPWM control method can improve the rectification efficiency, while effectively reducing the harmonic components, thereby effectively reducing the harmonic components input to the grid side through the new energy power supply system. Moreover, while the SVPWM modulation method is used to improve the rectification efficiency of the three-phase rectifier circuit, the power factor of the circuit is improved, thereby reducing the voltage pulsation at the DC bus. Furthermore, the DC conversion circuit adopts a full-bridge cascade topology, and the midpoint voltage balance is adjusted by controlling the duty cycle of the input signal of the DC conversion circuit. The operating cycle of the DC conversion circuit is 1 / 2 of the three-phase rectifier circuit, so it is faster to adjust the midpoint voltage by adjusting the duty cycle of the DC conversion circuit to achieve balance.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a power supply device of a new energy hydrogen production system, a new energy hydrogen production system and a control method. Background Art

[0002] The growing demand for energy has driven the development of renewable energy (such as wind and solar energy). The reserves of wind and solar energy are abundant, clean, pollution-free and easy to obtain, making them the main force of renewable energy. However, as the proportion of wind power and photovoltaic power generation continues to increase, while the construction of power grids and the absorption mechanism lag behind, the phenomenon of wind and solar power abandonment has emerged. The electrolysis of water to produce hydrogen can convert the electricity generated by local wind and solar energy into hydrogen storage, avoiding the high cost and safety issues caused by the unstable long-distance transmission of electricity, while solving the problems of wind and solar power abandonment caused by the intermittent and volatile nature of wind and solar energy.

[0003] The electrolyzer is a key equipment in the electrolysis of water hydrogen production technology. The electrolyzer is composed of multiple electrolytic cells. The electrolyzer can be regarded as a low-voltage large DC load. In order to avoid the frequent start and stop of the electrolyzer due to the unstable output of wind and solar power generation, extend the service life of the hydrogen production equipment and improve the hydrogen production efficiency. The power supply design of the electrolysis of water hydrogen production system based on new energy needs to meet the working characteristics of large current and low ripple on the hydrogen production side of the electrolyzer, and at the same time be able to adapt to the strong volatility of the output power of new energy. However, the power supply device of the current hydrogen production system cannot meet the above requirements. Summary of the invention

[0004] In view of the above problems, the present application provides a power supply device, a new energy hydrogen production system and a control method for a new energy hydrogen production system, so as to provide a large current and low ripple power supply current for the water electrolysis hydrogen production system, and at the same time, can promptly respond to the strong fluctuation of the output power of the power supply based on the new energy. The specific scheme is as follows:

[0005] In a first aspect, the present application provides a power supply device for a new energy hydrogen production system, comprising: a three-phase buck rectifier circuit, a DC conversion circuit and a controller, wherein the DC conversion circuit comprises a cascaded first DC conversion circuit and a second DC conversion circuit;

[0006] The input end of the three-phase buck rectifier circuit is connected to the new energy power supply system, and the output end of the three-phase buck rectifier circuit includes a first output capacitor and a second output capacitor connected in series;

[0007] The input end of the first DC conversion circuit is connected to the two ends of the first output capacitor, the first output end of the first DC conversion circuit is connected to the first end of the electrolytic cell load, and the second output end of the first DC conversion circuit is connected to the first output end of the second DC conversion circuit;

[0008] The input end of the second DC conversion circuit is connected to the two ends of the second output capacitor, and the second output end of the second DC conversion circuit is connected to the second end of the electrolytic cell load;

[0009] The controller is used to control the three-phase buck rectifier circuit based on space vector pulse width modulation, and to control the first DC conversion circuit and the second DC conversion circuit using a phase shift control strategy.

[0010] In a possible implementation, the input end of the first DC conversion circuit is connected to the two ends of the first output capacitor, the first output end of the first DC conversion circuit is connected to the first end of the electrolytic cell load, and the second output end of the first DC conversion circuit is connected to the first output end of the second DC conversion circuit, including:

[0011] The first DC conversion circuit includes a first isolation transformer, a first full-bridge structure connected to a first primary winding of the first isolation transformer, and a first rectifier structure connected to a first secondary winding of the first isolation transformer;

[0012] The input end of the first full-bridge structure is connected to the two ends of the first output capacitor of the three-phase buck rectifier circuit, and the output end of the first full-bridge structure is connected to the two ends of the first primary winding;

[0013] The first end of the first rectifying structure is connected to the first end of the first secondary winding, the second end of the first rectifying structure is connected to the second end of the first secondary winding, and the first end of the first rectifying structure is connected to the second end of the first output capacitor through the first output inductor, the second end of the first rectifying structure is connected to the second end of the first output capacitor through the second output inductor, and the second end of the first output capacitor is connected to the first end of the electrolytic cell load, and the midpoint of the first rectifying structure is connected to the first end of the first output capacitor.

[0014] In a possible implementation, the first full-bridge structure includes a first bridge arm and a second bridge arm connected in parallel, the first bridge arm includes a first switch tube and a second switch tube connected in series, the second bridge arm includes a third switch tube and a fourth switch tube connected in series, the series connection point of the first switch tube and the second switch tube is connected to the first end of the primary winding, and the series connection point of the third switch tube and the fourth switch tube is connected to the second end of the primary winding.

[0015] In a possible implementation, the first rectifying structure includes a first rectifying tube and a second rectifying tube connected in series, and a series connection point between the first rectifying tube and the second rectifying tube is connected to a first end of the first output capacitor.

[0016] In a possible implementation, the second DC conversion circuit includes a second isolation transformer, a second full-bridge structure connected to a second primary winding of the second isolation transformer, and a second rectifier structure connected to a second secondary winding of the second isolation transformer;

[0017] The input end of the second full-bridge structure is connected to the two ends of the second output capacitor of the three-phase buck rectifier circuit, and the output end of the second full-bridge structure is connected to the two ends of the second primary winding.

[0018] The first end of the second rectifying structure is connected to the first end of the second secondary winding, the first end of the second rectifying structure is connected to the second end of the second output capacitor through the third output inductor, the second end of the second rectifying structure is connected to the second end of the second secondary winding, and the second end of the second rectifying structure is connected to the second end of the second output capacitor through the fourth output inductor, the midpoint of the second rectifying structure is connected to the first end of the second output capacitor, and the first end of the second output capacitor is connected to the second end of the electrolytic cell load.

[0019] In a possible implementation, the input end of the three-phase buck rectifier circuit is connected to the new energy power supply system, and the output end of the three-phase buck rectifier circuit includes a first output capacitor and a second output capacitor connected in series, including:

[0020] The three-phase buck rectifier circuit includes an A-phase bridge arm, a B-phase bridge arm, a C-phase bridge arm, a unidirectional conductive device, a first inductor, a second inductor, and an output capacitor branch, wherein the output capacitor branch includes the first output capacitor and the second output capacitor connected in series;

[0021] The AC end of the A-phase bridge arm is connected to the A-phase AC power, the first DC end of the A-phase bridge arm is connected to the first end of the output capacitor branch through the first inductor, and the second DC end of the A-phase bridge arm is connected to the second end of the output capacitor branch through the second inductor;

[0022] The AC end of the B-phase bridge arm is connected to the B-phase AC power, and the DC end of the B-phase bridge arm is connected in parallel with the A-phase bridge arm;

[0023] The AC end of the C-phase bridge arm is connected to the C-phase AC power, and the DC end of the C-phase bridge arm is connected in parallel with the A-phase bridge arm;

[0024] The unidirectional conducting device is connected in parallel to the two DC ends of the A-phase bridge arm.

[0025] In a possible implementation, the bridge arm of each phase includes an upper half bridge arm and a lower half bridge arm, the upper half bridge arm includes a first switch branch, the lower half bridge arm includes a second switch branch, and the first switch branch and the second switch branch have unidirectional conductivity.

[0026] In a possible implementation, the upper half bridge arm includes two fifth switching tubes and a sixth switching tube connected in series, the drain of the fifth switching tube is connected to the drain of the sixth switching tube, the source of the fifth switching tube is connected to the first inductor, and the source of the sixth switching tube is connected to alternating current.

[0027] A second aspect of the present application provides a new energy hydrogen production system, comprising an electrolyzer, and a power supply device as described in any one of the first aspects, wherein the electrolyzer is connected to both ends of the power supply device.

[0028] A third aspect of the present application provides a method for controlling a power supply device of a new energy hydrogen production system, characterized in that it is used to control the power supply device according to any one of the first aspects, and the method includes:

[0029] Determining a target output current vector of a three-phase rectifier circuit according to a target output power;

[0030] Convert the target output current vector into a command current vector in a dq coordinate system;

[0031] According to the SVPWM modulation strategy, the target sector corresponding to the command current vector and the action time of the basic vector of the target sector are determined;

[0032] Determine the switching time of each power tube in the three-phase rectifier circuit according to the action time of the basic vector;

[0033] Controlling the duty cycle of the input signals of the two isolated full-bridge DC / DC converter circuits in the DC converter circuit so that the power supply voltage of the electrolyzer remains stable;

[0034] When it is detected that the midpoint voltage on the output side of the three-phase rectifier circuit is positive, the input signal duty cycle of the second isolated full-bridge DC / DC converter circuit in the DC converter circuit is increased according to the mapping relationship between the value of the midpoint voltage and the input signal duty cycle;

[0035] When it is detected that the midpoint voltage on the output side of the three-phase rectifier circuit is negative, the input signal duty cycle of the first isolated full-bridge DC / DC converter circuit in the DC converter circuit is increased according to the mapping relationship between the midpoint voltage value and the input signal duty cycle.

[0036] The power supply device of the new energy hydrogen production system provided in the embodiment of the present application adopts a three-phase buck rectification structure in the three-phase rectification circuit, and adopts an SVPWM modulation method to control the three-phase rectification circuit. The SVPWM control method can improve the rectification efficiency and effectively reduce the harmonic components, thereby effectively reducing the harmonic components input to the grid side through the new energy power supply system. Moreover, while the SVPWM modulation method is used to improve the rectification efficiency of the three-phase rectification circuit, the power factor of the circuit is improved, thereby reducing the voltage pulsation at the DC bus. Furthermore, the DC conversion circuit adopts a full-bridge cascade topology, and the midpoint voltage balance is adjusted by controlling the duty cycle of the input signal of the DC conversion circuit. The operating cycle of the DC conversion circuit is 1 / 2 of that of the three-phase rectification circuit, so the speed of achieving balance by adjusting the midpoint voltage by adjusting the duty cycle of the DC conversion circuit is faster, and the method of adjusting the input duty cycle is simpler than adjusting the action time of the small vector. In addition, in scenarios where the output power of the renewable energy power generation system fluctuates greatly, a buck structure is used in the three-phase rectifier circuit to reduce voltage stress, and a dual transformer is used in the DC conversion circuit to reduce current stress (i.e., current ripple is reduced and current efficiency is improved), thereby greatly improving the power supply device's resistance to power supply fluctuations, thereby effectively ensuring that when the power supply of the hydrogen production system fluctuates violently, it maintains a high step-down ratio and stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0038] Figure 1 A schematic diagram of the structure of a new energy hydrogen production system provided in this application;

[0039] Figure 2 A circuit topology diagram of a power supply device for a new energy hydrogen production system provided in this application;

[0040] Figure 3 A basic vector diagram of SVPWM modulation provided by this application;

[0041] Figure 4 It is a schematic diagram of a circuit state of a power supply device of a new energy hydrogen production system provided by the present application;

[0042] Figure 5 It is a schematic diagram of another circuit state of the power supply device of the new energy hydrogen production system provided by the present application;

[0043] Figure 6 It is a flow chart of a control method of a power supply device of a new energy hydrogen production system provided in this application. DETAILED DESCRIPTION

[0044] The following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0045] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0046] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, which is only to describe the distinction mode adopted by the objects of the same attributes when describing in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0047] See also Figure 1 , shows a schematic diagram of a water electrolysis hydrogen production system provided in an embodiment of the present application, the water electrolysis hydrogen production system includes a new energy power generation device 101, a three-phase rectifier circuit 102, a DC conversion circuit 103 and an electrolytic cell 104.

[0048] The new energy power generation equipment 101 can generate electric energy using renewable resources. For example, the new energy power generation equipment 101 can be a wind power generation equipment, a photovoltaic power generation equipment, etc.

[0049] The three-phase rectifier circuit 102 is used to convert the three-phase alternating current output by the new energy power generation device 101 into direct current. In some embodiments of the present application, the three-phase rectifier circuit 102 may adopt a three-phase buck rectifier circuit structure.

[0050] The DC conversion circuit 103 is used to convert the DC power output by the three-phase rectifier circuit 102 into electric energy that can be used by the electrolytic cell 104. The DC conversion circuit 103 is a DC / DC converter.

[0051] In some embodiments of the present application, the three-phase rectifier circuit 102 and the DC conversion circuit 103 may be referred to as a power supply device of the hydrogen production system.

[0052] The electrolyzer 104 is used to electrolyze water to obtain hydrogen.

[0053] See also Figure 2 , showing a schematic structural diagram of a power supply device of a water electrolysis hydrogen production system provided in an embodiment of the present application.

[0054] In this embodiment, the three-phase rectifier circuit 102 adopts a three-phase buck rectifier circuit and adopts space vector pulse width modulation (SVPWM) control.

[0055] The DC conversion circuit 103 adopts an isolated DC converter, wherein the primary side adopts a full-bridge cascade topology and is controlled by a phase-shift control strategy, and the output rectification loop topology of the secondary side adopts a current-doubler rectification structure.

[0056] like Figure 2 As shown, the input of the three-phase rectifier circuit 102 is connected to a three-phase AC power source, which may be AC ​​power generated by a photovoltaic power generation device or a wind power generation device, or AC power generated by other renewable energy sources, which is not limited in the present application.

[0057] Phase A, phase B and phase C of the three-phase rectifier circuit each include a rectifier bridge arm, and there are three rectifier bridge arms in total for the three phases, each bridge arm includes an upper bridge arm and a lower bridge arm. Among them, the upper bridge arm of phase A includes switch tube T1, and the lower bridge arm includes switch tube T6; the upper bridge arm of phase B includes switch tube T3, and the lower bridge arm is T4; the upper bridge arm of phase C includes switch tube T5, and the lower bridge arm includes switch tube T2. All six bridge arms need to have unidirectional conductive characteristics.

[0058] Two ends of the three-phase bridge arm are connected in parallel with a unidirectional conducting device, where the unidirectional conducting device is a diode D1.

[0059] One end of the upper bridge arm of each phase is connected to the output inductor Lp, and the other end of the upper bridge arm is connected to the input power supply of the corresponding phase. One end of the lower bridge arm of each phase is connected to the corresponding input power supply, and the other end is connected to the output inductor Ln. The other end of Lp is connected to one end of the output capacitor branch, and the other end of the output capacitor is connected to the other end of Ln. The output capacitor is connected in parallel to the output end of the three-phase rectifier circuit. Figure 2 As shown, the output capacitor includes a first capacitor C1 and a second capacitor C2 connected in series, wherein the connection point of C1 and C2 is a neutral point.

[0060] In some embodiments, the above T1 to T6 can all use MOS tubes. Considering the presence of parasitic diodes in MOS tubes, to prevent current backflow, each upper / lower bridge arm can be composed of a MOS tube and a fast diode in series. Alternatively, in order to improve the overall conversion efficiency of the three-phase rectifier circuit, two MOS tubes of the same type can be connected back to back. For example, Figure 2In the example shown, T1 includes two NMOS tubes connected back to back. Specifically, the drains of the two NMOS tubes are connected, the source of one NMOS is connected to the output inductor Lp, and the source of the other NMOS is connected to the A-phase power supply.

[0061] The gate of each MOS tube in all bridge arms is connected to the corresponding output terminal of the controller, that is, the controller outputs a corresponding control signal to control the bridge arm to be turned on or off.

[0062] The input end of the DC conversion circuit 103 is connected to the output end of the three-phase rectification circuit 102, that is, the two ends of the series branch of C1 and C2.

[0063] In some embodiments, the DC conversion circuit 103 includes two isolated full-bridge DC / DC conversion circuits connected in cascade at the primary side and in parallel at the secondary side, which can be referred to as a first isolated full-bridge DC / DC conversion circuit (or a first DC conversion circuit) and a second isolated full-bridge DC / DC conversion circuit (or a second DC conversion circuit). The first and second isolated full-bridge DC / DC conversion circuits have the same circuit topology.

[0064] The input ends of the two isolated full-bridge DC / DC conversion circuits are respectively connected to the output ends of the three-phase rectifier circuit 102, that is, the two ends of the series branch of capacitors C1 and C2. Among them, the input end of the first isolated full-bridge DC / DC conversion circuit is connected to the first capacitor C1 at the output end of the three-phase rectifier circuit 102. The input end of the second isolated full-bridge DC / DC conversion circuit is connected to the second capacitor C2 at the output end of the three-phase rectifier circuit 102. The output ends of the two isolated full-bridge DC / DC conversion circuits are connected in parallel and connected to the load, and the load here is the electrolytic cell.

[0065] The following takes the first isolated full-bridge DC / DC converter circuit as an example to illustrate its circuit topology:

[0066] In the embodiment of the present application, the primary side of the isolated full-bridge DC / DC converter circuit is a full-bridge topology, and the secondary side adopts a current doubler rectification topology, such as Figure 2 As shown, the primary side topology of the isolated DC / DC conversion circuit includes two bridge arms, each bridge arm includes an upper bridge arm and a lower bridge arm, and the upper / lower bridge arm includes at least one switch tube.

[0067] The following is an example in which each upper / lower bridge arm includes a switch tube. The two bridge arms include switch tubes S1-S4, wherein S1 and S2 are connected in series and then connected in parallel to the first capacitor C1 at the output end of the three-phase rectifier circuit. Similarly, S3 and S4 are connected in series and then connected in parallel to the two ends of C1, wherein the connection point of S1 and S2 is connected to one end of the primary winding of the isolation transformer TR, and the connection point of S3 and S4 is connected to the other end of the primary winding of the isolation transformer TR.

[0068] In this embodiment, S1 and S2 are connected in series, which means the source and drain are connected in series, such as the source of S1 is connected to the drain of S2, the drain of S1 is connected to one end of C1, and the source of S2 is connected to the other end of C1. Similarly, S3 and S4 are connected in series, which means the source of S3 is connected to the drain of S4.

[0069] The secondary winding of the isolation transformer TR is connected to a rectifier topology, which includes at least two switch tubes connected in series. Figure 2 As shown, two switches are connected in series as an example. SR1 and SR2 are connected in series to the two ends of the secondary winding. Specifically, the source of SR1 is connected to the drain of SR2, the drain of SR1 is connected to one end of the secondary winding, and the source of SR2 is connected to the other end of the secondary winding. Among them, the connection point of SR1 and SR2 is connected to the first end of the output capacitor Ccp. The drain of SR1 is connected to the second end of Ccp through the first inductor Lcp1. The source of SR2 is also connected to the second end of Ccp through the second inductor Lcp2. At the same time, the second end of Ccp is connected to the first end of the load RL. Among them, the functions of Ccp and Ccn are mainly filtering. The main functions of Lcp1, Lcp2, Lcn1, and Lcn2 are filtering.

[0070] The input end of the second isolated full-bridge DC / DC conversion circuit is connected to the two ends of the second capacitor C2 of the three-phase rectifier circuit, the first end of the output capacitor Ccn of the second isolated full-bridge DC / DC conversion circuit is connected to the second end of the load RL, and the second end of Ccn is connected to the first end of Ccp of the first isolated full-bridge DC / DC conversion circuit.

[0071] In some embodiments, the switch tubes in the DC conversion circuit can all be MOS tubes, such as PMOS tubes. Of course, other types of switch tubes can also be used, and this application does not impose any restrictions on this.

[0072] Combine the following Figure 2 The circuit topology shown introduces its control process:

[0073] The SVPWM modulation strategy is adopted to control the switch state of each bridge arm in the three-phase rectifier circuit 102, so that the output voltage is the target DC voltage.

[0074] Exemplarily, the control logic of the three-phase rectifier circuit is as follows: the target output current vector is obtained according to the target output power, that is, the target output current vector is further converted into a current vector in the dq coordinate system, that is, the command current vector I*. According to the SVPWM modulation strategy, the sector corresponding to the command current vector I* is determined, and the action time corresponding to the relevant basic vector in the sector is calculated, and finally the switching time of each power device in the three-phase rectifier circuit is determined according to the action time of the basic vector.

[0075] According to the SVPWM modulation strategy, a corresponding current vector (which may be called a synthetic current vector) is synthesized using part of the current vectors in the eight basic space current vectors (two zero current vectors and six non-zero current vectors) so that the synthetic current vector is equal to the command current vector I*.

[0076] Among them, the SVPWM modulation method is to define each bridge arm of the three bridge arms ABC as two states of 0 and 1, among which "0" means that the upper bridge arm is turned off and the lower bridge arm is turned on, and "1" means that the upper bridge arm is turned on and the lower bridge arm is turned off. The three bridge arms can obtain eight combination states, and these eight states can be represented by 3-bit binary numbers: 000, 001, 010, 011, 100, 101, 110, 111. Among them, the 3-bit binary number represents the states of the C phase, B phase and A phase bridge arms from high to low. For example, 010 means that the upper bridge arm of the C phase and the A phase is turned off and the lower bridge arm is turned on, and the upper bridge arm of the B phase is turned on and the lower bridge arm is turned off. The upper bridge arm is turned on / off specifically refers to the switch tube located in the upper bridge arm being turned on / off, and the lower bridge arm is turned on / off in the same way.

[0077] When the three-phase rectifier circuit is in the above eight states respectively, eight space vectors can be obtained, namely the above eight basic space current vectors, among which 000 and 111 both correspond to zero vectors, and the other six combination states correspond to six non-zero current vectors respectively.

[0078] like Figure 3 As shown, the six non-zero current vectors I1-I6 divide the complex plane into six sectors I-VI. Any vector in any sector can be decomposed into vectors along the directions of its two adjacent non-zero basic vectors. In other words, the amplitude and direction of any vector in the sector surrounded by the two non-zero basic vectors can be calculated based on the two adjacent non-zero basic vectors and one or two zero vectors. For example, the current vector I in sector I can be synthesized by the basic current vectors I1 and I3.

[0079] For a three-phase balanced system, the input power is constant, the output DC voltage is also constant, and therefore, the current flowing through the output inductor Lp / Ln is also constant. In other words, the three-phase rectifier circuit obtains a constant current source in the output inductor.

[0080] For a given current vector and its action time in a sector, there are many synthesis methods within a modulation period Ts. Within a modulation period Ts, the distribution of the basic vector does not affect the average output, but it will affect the linear modulation area and harmonic characteristics of the output. Therefore, in order to balance the power consumption and harmonic phases, the present application adopts a seven-segment SVPWM modulation method. This modulation method aims to reduce the number of switches and selects the distribution of the basic vector action sequence: at each switch state conversion, only the switch state of one phase is changed, and the zero vector is evenly distributed in time, thereby effectively reducing the harmonic components generated by the power electronic equipment in the circuit.

[0081] This modulation method can improve the rectification efficiency, effectively reduce the harmonic components, and thus reduce the harmonic components input to the grid through the new energy power supply. Moreover, the SVPWM modulation method improves the rectification efficiency of the three-phase rectifier circuit while improving the power factor of the circuit, thereby reducing the voltage pulsation at the DC bus (i.e., the DC output end of the series Lp / Ln).

[0082] The three-phase rectifier circuit uses SVPWM modulation to improve the rectification efficiency. However, the speed of adjusting the midpoint voltage by a small vector is slow and the coupling is weak (i.e., insufficient directness), which leads to obvious bias at the midpoint (i.e., the connection point of C1 and C2). In the scenario where the output power of the new energy power generation system fluctuates greatly, the power tube will be damaged by the peak voltage shock.

[0083] The primary side of the DC conversion circuit of the present application adopts a full-bridge cascade structure, and the midpoint voltage balance is achieved by adjusting the operating time of the upper and lower isolation transformers (that is, adjusting the input duty cycle of the isolation transformer, the larger the duty cycle, the longer the input signal time, and the smaller the duty cycle, the shorter the input signal time). For example, when the midpoint voltage is a positive value, the input signal duty cycle of the lower transformer can be increased, which is equivalent to extending the operating time of the second isolated full-bridge DC / DC conversion circuit and reducing the output side midpoint voltage. When the midpoint voltage is a negative value, increasing the input signal duty cycle of the upper transformer is equivalent to extending the operating time of the first isolated full-bridge DC / DC conversion circuit and increasing the midpoint voltage.

[0084] Moreover, the operating cycle of the DC conversion circuit is 1 / 2 of that of the three-phase rectifier circuit, so it is faster to adjust the midpoint voltage to achieve balance by adjusting the duty cycle of the DC conversion circuit. In addition, the method of adjusting the input duty cycle is simpler than adjusting the action time of the small vector.

[0085] Combine the following Figure 4-Figure 5 Introduce the working process of DC conversion circuit:

[0086] like Figure 4As shown, S1 and S4 in the first isolated full-bridge DC / DC conversion circuit are turned on, S2 and S3 are turned off, and the electric energy on the output capacitor C1 of the three-phase rectifier circuit flows into the primary winding of the isolation transformer TR through S1 and S4. Further, the energy flows from the primary winding to the secondary winding. At this time, the synchronous rectifier SR1 is turned on and SR2 is turned off. Similarly, in the second isolated full-bridge DC / DC conversion circuit at this moment, S5 and S8 are turned on, S6 and S7 are turned off, the synchronous rectifier SR3 is turned on, and SR4 is turned off.

[0087] Among them, when S1 and S4 are turned on, and S2 and S3 are turned off, the polarity of the secondary voltage of the first isolated full-bridge DC / DC conversion circuit is positive, ensuring that SR1 is turned on and SR2 is turned off. At the same time, when S5 and S8 are turned on, and S6 and S7 are turned off, the polarity of the secondary voltage of the second isolated full-bridge DC / DC conversion circuit is also positive, SR3 is turned on and SR4 is turned off, and the secondary current flow direction of the two DC / DC conversion circuits is shown in the direction of the arrow in the figure.

[0088] See also Figure 5 , in the first isolated full-bridge DC / DC conversion circuit, S1 and S4 on the primary side are turned off, S2 and S3 are turned on, SR1 on the secondary side is turned off, and SR2 is turned on. Similarly, in the second isolated full-bridge DC / DC conversion circuit, S5 and S8 on the primary side are turned off, S6 and S7 are turned on, the synchronous rectifier SR3 is turned off, and SR4 is turned on. At this time, the secondary voltage polarity of the two isolated full-bridge DC / DC conversion circuits is negative, and the secondary current flow direction of the two DC / DC conversion circuits is shown in the direction of the arrow in the figure.

[0089] In addition, Figure 4 The circuit status shown is similar to Figure 5 There are multiple states between the circuit states shown to achieve soft switching. The ideal soft switching process is that the current or voltage first drops to zero, and then the voltage or current slowly rises to the off-state value, so the switching loss is approximately zero. Soft switching can achieve high frequency of power conversion devices.

[0090] In summary, the power supply device of the new energy hydrogen production system provided in the embodiment of the present application, the three-phase rectifier circuit adopts a three-phase buck rectifier structure, and the three-phase rectifier circuit is controlled by the SVPWM modulation method. The SVPWM control method can improve the rectification efficiency and effectively reduce the harmonic components, thereby effectively reducing the harmonic components input to the grid side through the new energy power supply system. Moreover, while the SVPWM modulation method is used to improve the rectification efficiency of the three-phase rectifier circuit, the power factor of the circuit is improved, thereby reducing the voltage pulsation at the DC bus. Furthermore, the DC conversion circuit adopts a full-bridge cascade topology, and the midpoint voltage balance is adjusted by controlling the duty cycle of the input signal of the DC conversion circuit. The operating cycle of the DC conversion circuit is 1 / 2 of the three-phase rectifier circuit, so it is faster to adjust the midpoint voltage to achieve balance by adjusting the duty cycle of the DC conversion circuit, and the method of adjusting the input duty cycle is simpler than adjusting the action time of the small vector. In addition, in scenarios where the output power of the renewable energy power generation system fluctuates greatly, a buck structure is used in the three-phase rectifier circuit to reduce voltage stress, and a dual transformer is used in the DC conversion circuit to reduce current stress (i.e., current ripple is reduced and current efficiency is improved), thereby greatly improving the power supply device's resistance to power supply fluctuations, thereby effectively ensuring that when the power supply of the hydrogen production system fluctuates violently, it maintains a high step-down ratio and stable operation.

[0091] In addition, the DC conversion circuit adopts a cascade structure, and the current of each isolated full-bridge DC / DC conversion circuit is only half of the rectifier current, which reduces the current size of a single DC / DC conversion circuit, thereby reducing the requirements of the DC / DC conversion circuit on inductor materials, and can use an inductor with a smaller rated current value, thereby reducing the hardware cost of the inductor, and further reducing the overall cost of the power supply device. At the same time, the transformer leakage inductance is used to achieve soft switching of the full bridge, thereby reducing switching losses.

[0092] Corresponding to the power supply device of the new energy hydrogen production system, the present application also provides a control method of the power supply device, which can be run in the controller of the power supply device of the new energy hydrogen production system, such as Figure 6 As shown, the method may include:

[0093] S101, determining a target output current vector of a three-phase rectifier circuit according to a target output power.

[0094] S102, converting the target output current vector into a command current vector in the dq coordinate system.

[0095] S103, determining the target sector corresponding to the command current vector and the action time of the basic vector of the target sector according to the SVPWM modulation strategy.

[0096] S104, determining the switching time of each power tube in the three-phase rectifier circuit according to the action time of the basic vector.

[0097] S105, controlling the duty ratio of the input signals of the two isolated full-bridge DC / DC conversion circuits in the DC conversion circuit so that the power supply voltage of the electrolytic cell remains stable.

[0098] S106, when it is detected that the midpoint voltage on the output side of the three-phase rectifier circuit is positive, the input signal duty cycle of the second isolated full-bridge DC / DC converter circuit in the DC converter circuit is increased according to the mapping relationship between the value of the midpoint voltage and the input signal duty cycle.

[0099] The mapping relationship between the input signal duty cycle and the midpoint voltage deviation of the isolated full-bridge DC / DC converter circuit can be obtained based on a limited number of experiments. This application does not impose any restrictions on this.

[0100] S107, when it is detected that the midpoint voltage on the output side of the three-phase rectifier circuit is negative, the input signal duty cycle of the first isolated full-bridge DC / DC converter circuit in the DC converter circuit is increased according to the mapping relationship between the value of the midpoint voltage and the input signal duty cycle.

[0101] The power supply device control method of the new energy hydrogen production system provided in this embodiment adopts a three-phase buck rectification structure for the three-phase rectification circuit, and adopts an SVPWM modulation method to control the three-phase rectification circuit. The SVPWM control method can improve the rectification efficiency and effectively reduce the harmonic components, thereby effectively reducing the harmonic components input to the grid side through the new energy power supply system. Moreover, the SVPWM modulation method improves the power factor of the circuit, thereby reducing the voltage pulsation at the DC bus. Furthermore, the DC conversion circuit adopts a full-bridge cascade topology, and the midpoint voltage balance is adjusted by controlling the duty cycle of the input signal of the DC conversion circuit. The operating cycle of the DC conversion circuit is 1 / 2 of that of the three-phase rectification circuit, so it is faster to adjust the midpoint voltage to achieve balance by adjusting the duty cycle of the DC conversion circuit, and the method of adjusting the input duty cycle is simpler than adjusting the action time of the small vector. In addition, in scenarios where the output power of the renewable energy power generation system fluctuates greatly, a buck structure is used in the three-phase rectifier circuit to reduce voltage stress, and a dual transformer is used in the DC conversion circuit to reduce current stress (i.e., current ripple is reduced and current efficiency is improved), thereby greatly improving the power supply device's resistance to power supply fluctuations, thereby effectively ensuring that when the power supply of the hydrogen production system fluctuates violently, it maintains a high step-down ratio and stable operation.

[0102] It should also be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the drawings of the device embodiments provided by the present application, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines.

[0103] Through the description of the above implementation mode, the technicians in the field can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present application, software program implementation is a better implementation mode in more cases. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0104] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

Claims

1. A power supply device for a new energy hydrogen production system, characterized in that: include: A three-phase buck rectifier circuit, a DC conversion circuit and a controller, wherein the DC conversion circuit includes a cascaded first DC conversion circuit and a second DC conversion circuit; The input end of the three-phase buck rectifier circuit is connected to the new energy power supply system, and the output end of the three-phase buck rectifier circuit includes a first output capacitor and a second output capacitor connected in series; The input end of the first DC conversion circuit is connected to the two ends of the first output capacitor, the first output end of the first DC conversion circuit is connected to the first end of the electrolytic cell load, and the second output end of the first DC conversion circuit is connected to the first output end of the second DC conversion circuit; The input end of the second DC conversion circuit is connected to the two ends of the second output capacitor, and the second output end of the second DC conversion circuit is connected to the second end of the electrolytic cell load; The controller is used to control the three-phase buck rectifier circuit based on space vector pulse width modulation, and to control the first DC conversion circuit and the second DC conversion circuit using a phase shift control strategy.

2. The power supply device according to claim 1, characterized in that: The input end of the first DC conversion circuit is connected to the two ends of the first output capacitor, the first output end of the first DC conversion circuit is connected to the first end of the electrolytic cell load, and the second output end of the first DC conversion circuit is connected to the first output end of the second DC conversion circuit, including: The first DC conversion circuit includes a first isolation transformer, a first full-bridge structure connected to a first primary winding of the first isolation transformer, and a first rectifier structure connected to a first secondary winding of the first isolation transformer; The input end of the first full-bridge structure is connected to the two ends of the first output capacitor of the three-phase buck rectifier circuit, and the output end of the first full-bridge structure is connected to the two ends of the first primary winding; The first end of the first rectifying structure is connected to the first end of the first secondary winding, the second end of the first rectifying structure is connected to the second end of the first secondary winding, and the first end of the first rectifying structure is connected to the second end of the first output capacitor through the first output inductor, the second end of the first rectifying structure is connected to the second end of the first output capacitor through the second output inductor, and the second end of the first output capacitor is connected to the first end of the electrolytic cell load, and the midpoint of the first rectifying structure is connected to the first end of the first output capacitor.

3. The power supply device according to claim 2, characterized in that: The first full-bridge structure includes a first bridge arm and a second bridge arm connected in parallel, the first bridge arm includes a first switch tube and a second switch tube connected in series, the second bridge arm includes a third switch tube and a fourth switch tube connected in series, the series connection point of the first switch tube and the second switch tube is connected to the first end of the primary winding, and the series connection point of the third switch tube and the fourth switch tube is connected to the second end of the primary winding.

4. The power supply device according to claim 2 or 3, characterized in that: The first rectifying structure includes a first rectifying tube and a second rectifying tube connected in series, and a series connection point between the first rectifying tube and the second rectifying tube is connected to a first end of the first output capacitor.

5. The power supply device according to claim 2, characterized in that: The second DC conversion circuit includes a second isolation transformer, a second full-bridge structure connected to a second primary winding of the second isolation transformer, and a second rectifier structure connected to a second secondary winding of the second isolation transformer; The input end of the second full-bridge structure is connected to the two ends of the second output capacitor of the three-phase buck rectifier circuit, and the output end of the second full-bridge structure is connected to the two ends of the second primary winding. The first end of the second rectifying structure is connected to the first end of the second secondary winding, the first end of the second rectifying structure is connected to the second end of the second output capacitor through the third output inductor, the second end of the second rectifying structure is connected to the second end of the second secondary winding, and the second end of the second rectifying structure is connected to the second end of the second output capacitor through the fourth output inductor, the midpoint of the second rectifying structure is connected to the first end of the second output capacitor, and the first end of the second output capacitor is connected to the second end of the electrolytic cell load.

6. The power supply device according to claim 1, characterized in that: The input end of the three-phase buck rectifier circuit is connected to the new energy power supply system, and the output end of the three-phase buck rectifier circuit includes a first output capacitor and a second output capacitor connected in series, including: The three-phase buck rectifier circuit includes an A-phase bridge arm, a B-phase bridge arm, a C-phase bridge arm, a unidirectional conductive device, a first inductor, a second inductor, and an output capacitor branch, wherein the output capacitor branch includes the first output capacitor and the second output capacitor connected in series; The AC end of the A-phase bridge arm is connected to the A-phase AC power, the first DC end of the A-phase bridge arm is connected to the first end of the output capacitor branch through the first inductor, and the second DC end of the A-phase bridge arm is connected to the second end of the output capacitor branch through the second inductor; The AC end of the B-phase bridge arm is connected to the B-phase AC power, and the DC end of the B-phase bridge arm is connected in parallel with the A-phase bridge arm; The AC end of the C-phase bridge arm is connected to the C-phase AC power, and the DC end of the C-phase bridge arm is connected in parallel with the A-phase bridge arm; The unidirectional conducting device is connected in parallel to the two DC ends of the A-phase bridge arm.

7. The power supply device according to claim 6, characterized in that: The bridge arm of each phase includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes a first switch branch, the lower bridge arm includes a second switch branch, and the first switch branch and the second switch branch have unidirectional conductivity.

8. The power supply device according to claim 7, characterized in that: The upper bridge arm includes two fifth and sixth switch tubes connected in series, the drain of the fifth switch tube is connected to the drain of the sixth switch tube, the source of the fifth switch tube is connected to the first inductor, and the source of the sixth switch tube is connected to alternating current.

9. A new energy hydrogen production system, characterized in that: It comprises an electrolytic cell and a power supply device as claimed in any one of claims 1 to 8, wherein the electrolytic cell is connected to both ends of the power supply device.

10. A method for controlling a power supply device of a new energy hydrogen production system, characterized in that: Used to control the power supply device according to any one of claims 1 to 8, the method comprising: Determining a target output current vector of a three-phase rectifier circuit according to a target output power; Convert the target output current vector into a command current vector in a dq coordinate system; According to the SVPWM modulation strategy, the target sector corresponding to the command current vector and the action time of the basic vector of the target sector are determined; Determine the switching time of each power tube in the three-phase rectifier circuit according to the action time of the basic vector; Controlling the duty cycle of the input signals of the two isolated full-bridge DC / DC converter circuits in the DC converter circuit so that the power supply voltage of the electrolyzer remains stable; When it is detected that the midpoint voltage on the output side of the three-phase rectifier circuit is positive, the input signal duty cycle of the second isolated full-bridge DC / DC converter circuit in the DC converter circuit is increased according to the mapping relationship between the value of the midpoint voltage and the input signal duty cycle; When it is detected that the midpoint voltage on the output side of the three-phase rectifier circuit is negative, the input signal duty cycle of the first isolated full-bridge DC / DC converter circuit in the DC converter circuit is increased according to the mapping relationship between the midpoint voltage value and the input signal duty cycle.

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