Phase-shift control method of power supply module, three-phase power supply module and power supply system

Abstract

The application provides a phase-shifting control method of a power supply module, a three-phase power supply module and a power supply system. The power supply module comprises N inverter units corresponding to N AC side voltages, and the N inverter units are correspondingly coupled to N high-frequency AC ends which are connected in cascade with a subsequent rectifier circuit. The phase-shifting control method comprises: setting at least two phase-shifting sequences, wherein the phase arrangement numbers of the N AC side voltages of the N inverter units in the at least two phase-shifting sequences are all different; in a switching period, controlling the N AC side voltages of the N inverter units to be phase-shifted by a first angle in a first phase-shifting sequence of the at least two phase-shifting sequences; and in another switching period, controlling the N AC side voltages of the N inverter units to be phase-shifted by the first angle in a second phase-shifting sequence of the at least two phase-shifting sequences. The application realizes wide-range high-efficiency output and uniform power control, can inhibit the double-frequency fluctuation of a DC-Link voltage, and can reduce the number of modules and the number of controllers.

Description

Technical Field

[0001] This invention relates to power electronics technology, and in particular to a phase-shifting control method for a power supply module, a three-phase power supply module, and a power supply system. Background Technology

[0002] Solid-state transformers (SSTs) have broad application prospects in DC power consumption or generation fields such as data centers, electric vehicle charging and swapping stations, photovoltaics, and energy storage. These applications generally require a wide output voltage range.

[0003] For example, data centers require the following power supply voltages: 240V (200-290V) for telecommunications; 336V (280-400V) for mobile; and 750V (625-900V) for the future. The battery charging voltage range for electric vehicle charging and swapping stations is 200V-500V or 200V-1000V.

[0004] Furthermore, as a power conversion system, SST (Self-Powered Transmission System) typically requires high efficiency. Additionally, since SSTs often involve high-voltage input and employ a modular structure, power balance between modules is generally desirable to facilitate consistent system design.

[0005] like Figure 1 The diagram illustrates the topology of an existing three-phase solid-state transformer (SST) 100' based on single-phase modules. The SST 100' is composed of three single-phase converters (A-phase, B-phase, and C-phase), each containing N modules 10'. For example, phase A contains N modules 10', from Cell1A to Cell NA. Each module 10' may include a preceding H-bridge circuit 11' (e.g., an AC-DC circuit) and a following DC-DC isolation circuit 12' (often an LLC circuit). The N modules 10' of each phase are connected in series at the input and parallel at the output (ISOP), for example, the input side is a cascaded H-bridge circuit (CHB), and the output is a parallel LLC isolation circuit. All three phase outputs are connected in parallel to form a total low-voltage DC bus (BUS). Figure 1 In the illustrated embodiment, a certain degree of wide-range voltage output can be achieved through phase shift control (boost) of the primary and secondary sides of the subsequent stage and duty cycle control (buck) of the primary side.

[0006] Depend on Figure 1 As can be seen, the existing topology contains a total of 3*N modules. The large number of modules increases the difficulty of system architecture design and hinders system integration. As the system further develops towards higher voltage, the number of modules will increase even more, multiplying by a factor of 3, which is detrimental to further expansion. Each module handles single-phase power, which exhibits second-harmonic frequency fluctuations, causing corresponding DC-link issues (such as...). Figure 1 The voltage fluctuations (shown in the darkened black area) or the second harmonic fluctuations of the LLC resonant cavity current are significant. Even with a power fluctuation suppression control loop, it is still difficult to suppress the second harmonic fluctuations of the LLC resonant cavity current, resulting in additional losses in the LLC circuit. Furthermore, three-phase LLC circuits are difficult to balance current, requiring complex voltage and current equalization algorithms to balance module power. Meanwhile, the options for adjusting the output voltage of the LLC circuit are extremely limited. Frequency modulation, phase shifting, or duty cycle adjustment can be used, but frequency modulation affects system efficiency, and phase shifting or duty cycle adjustment causes the loss of the ZVS (Zero Voltage Switch) in the primary-side inverter circuit of the LLC circuit, thus increasing losses.

[0007] For the LLC circuit topology in the subsequent stage, patent US10804809B1 proposes a high-frequency cascaded converter, in which the high-frequency AC terminals of each LLC, i.e., the secondary side of the transformer, are cascaded at high frequency and connected to an AC-DC circuit for output. Similar to the voltage regulation method of SST single-phase modules, it can achieve a certain degree of wide-range voltage output through phase shift control (boost) between the primary and secondary AC voltages and primary duty cycle control (buck). However, it also suffers from loss of ZVS when outputting over a wide range, affecting the system efficiency.

[0008] In addition, reference [1] (Bo Xue, etc., Shift Modulated Interleaved LLC Converter With Ultrawide Output Voltage Range, IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL.36, NO.1, 2021) discloses a high-frequency cascaded converter, in which the secondary sides of two LLC transformers are cascaded at high frequency and connected to an AC-DC circuit for output. The phase shift voltage regulation between the AC side voltages of the primary inverter unit is used, and the output voltage regulation control is achieved by the phase shift between the two primary high-frequency voltages. The primary inverter with this structure is less prone to loss of ZVS and has higher efficiency. However, as a single-phase module, it has two resonant cavities and two resonant circuits, which results in a relatively high cost. Summary of the Invention

[0009] The purpose of this invention is to provide a phase-shift control method for a power supply module, a three-phase power supply module, and a power supply system, which can solve one or more defects of the prior art.

[0010] To achieve the above objectives, according to an embodiment of the present invention, a phase-shift control method for a power supply module is provided. The power supply module includes N inverter units, each of which outputs N AC-side voltages, where N is a positive integer greater than or equal to 3. The N inverter units are coupled to N high-frequency AC terminals, which are cascaded and connected to a subsequent rectifier circuit. The phase-shift control method includes: setting at least two phase-shift sequences, wherein the phase arrangement numbers of the N AC-side voltages of the N inverter units are all different in the at least two phase-shift sequences; in one switching cycle, controlling the N AC-side voltages of the N inverter units to shift phase by a first angle relative to each other according to a first phase-shift sequence in the at least two phase-shift sequences; and in another switching cycle, controlling the N AC-side voltages of the N inverter units to shift phase by the first angle relative to each other according to a second phase-shift sequence in the at least two phase-shift sequences.

[0011] In one embodiment of the present invention, the duration of each phase shift sequence is at least m switching cycles, where m is a positive integer greater than or equal to 1.

[0012] In one embodiment of the present invention, when performing phase shift control, N phase shift sequences are set, and the N AC side voltages of the N inverter units are controlled to take turns shifting phases with each other in the N phase shift sequences.

[0013] In one embodiment of the present invention, in the N phase shifting sequences, the phase arrangement number of each inverter unit is different in the N phase shifting sequences.

[0014] In one embodiment of the present invention, the power supply module further includes N front-stage rectifier circuits, which are connected to the DC terminals of the N inverter units through an intermediate DC bus capacitor, and output N front-stage output voltages to the N inverter units accordingly; the phase-shift control method further includes: performing phase-to-phase voltage equalization control on the N front-stage output voltages.

[0015] In one embodiment of the present invention, the power supply module further includes N energy storage batteries, which are respectively connected to the DC terminals of the N inverter units.

[0016] In one embodiment of the present invention, the power supply module further includes N isolation transformers, which are correspondingly disposed between the N inverter units and the N high-frequency AC terminals; the N isolation transformers include N primary windings and N secondary windings, the N primary windings are correspondingly connected to the N inverter units, and the N secondary windings are correspondingly connected to the N high-frequency AC terminals.

[0017] In one embodiment of the present invention, when performing phase shift control, the AC side voltages on the primary side of the N isolation transformers are subjected to alternating phase shift control.

[0018] In one embodiment of the present invention, the larger the first angle, the smaller the output voltage of the subsequent rectifier circuit.

[0019] To achieve the above objectives, the present invention further provides a three-phase power supply module, comprising: three front-stage single-phase rectifier circuits electrically coupled to a three-phase AC power supply at their AC terminals; three intermediate DC bus capacitors; three inverter units corresponding to output three AC-side voltages, wherein the front-stage rectifier circuits are connected to the inverter units one-to-one through the intermediate DC bus capacitors; three high-frequency AC terminals corresponding to the three inverter units; a rear-stage rectifier circuit connected to the cascaded three high-frequency AC terminals; and a controller configured to perform phase-shift control, comprising: setting at least two phase-shift sequences, wherein the phase arrangement numbers of the three AC-side voltages of the three inverter units are all different in the at least two phase-shift sequences; in a switching cycle, controlling the three AC-side voltages of the three inverter units to shift phase by a first phase-shift sequence of the at least two phase-shift sequences by a first angle; and in another switching cycle, controlling the three AC-side voltages of the three inverter units to shift phase by the first angle in a second phase-shift sequence of the at least two phase-shift sequences.

[0020] In another embodiment of the present invention, the controller sets three phase shift sequences when performing phase shift control, and controls the three AC side voltages of the three inverter units to take turns shifting phases in the three phase shift sequences.

[0021] In another embodiment of the invention, the duration of each phase shift sequence is at least m switching cycles, where m is a positive integer greater than or equal to 1.

[0022] In another embodiment of the present invention, in the three phase shifting sequences, the phase arrangement number of each inverter unit is different in the three phase shifting sequences.

[0023] In another embodiment of the invention, the controller is further configured to perform phase-to-phase voltage equalization control on the three front-stage output voltages of the three front-stage rectifier circuits.

[0024] In another embodiment of the present invention, the three-phase power supply module further includes three isolation transformers, which are respectively disposed between the three inverter units and the three high-frequency AC terminals.

[0025] In another embodiment of the present invention, the controller performs phase-shift control on the AC side voltage of the primary side of the three isolation transformers in rotation.

[0026] To achieve the above objectives, the present invention provides a power supply system comprising at least two three-phase power supply modules as described above.

[0027] In another embodiment of the present invention, the output terminals of the at least two three-phase power supply modules are independent output terminals or connected in parallel to form a common DC output terminal.

[0028] In another embodiment of the present invention, the input terminals of the at least two three-phase power supply modules are either cascaded, independent, or connected in parallel.

[0029] In another embodiment of the present invention, the power supply system is a three-phase power supply system, including three three-phase power supply modules, and the AC side of the corresponding front-end rectifier circuits in the three three-phase power supply modules are cascaded and respectively connected to each phase of the three-phase AC power supply.

[0030] In another embodiment of the present invention, the controllers of each of the three-phase power supply modules are connected via communication lines.

[0031] This invention proposes a phase-shifting control method for high-frequency cascaded modules, achieving wide-range, high-efficiency output and power-averaging control. By combining a pre-stage AC-DC differential voltage controller with zero-sequence voltage injection, this invention can suppress second-harmonic frequency fluctuations in the DC-Link voltage.

[0032] The present invention also proposes a three-phase isolated three-phase power supply module, which can cancel the second harmonic fluctuation of the secondary voltage and eliminate the current imbalance of the three-phase resonant tank by cascading the three phases at high frequency.

[0033] The present invention also proposes an SST based on the three-phase isolated three-phase power supply module, wherein each power supply module includes a controller and is connected through a communication line, thereby reducing the number of modules and controllers.

[0034] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The above and other features and advantages of the present invention will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0036] Figure 1 This is a schematic diagram of the existing topology of a three-phase solid-state transformer based on a single-phase module;

[0037] Figure 2 This is a topology diagram of a three-phase power supply module according to a first preferred embodiment of the present invention;

[0038] Figure 3This is a schematic flowchart of the phase-shifting control method for the power supply module of the present invention;

[0039] Figure 4 It shows the basis Figure 2 The three-phase power supply module shown in this invention has three phase shift control modes, each corresponding to a phase shift control sequence;

[0040] Figure 5 A simulation waveform diagram of the alternating phase-shifting control method used in this invention is shown;

[0041] Figure 6 A schematic diagram showing the relationship between phase shift angle and gain in the phase shift control method of the present invention is shown;

[0042] Figure 7 This is a schematic diagram of the three-phase power supply system based on a three-phase power supply module according to the present invention;

[0043] Figure 8 This is a block diagram of the three-phase power supply system of the present invention for phase-to-phase voltage equalization control of the output voltage of the front stage;

[0044] Figure 9A The waveform diagram is shown for the front-stage rectifier circuit of this invention when phase-to-phase voltage equalization control is not used.

[0045] Figure 9B The waveform diagram shows the phase-to-phase voltage equalization control used in the front-end rectifier circuit of this invention.

[0046] Figure 10 This is a schematic diagram of the topology of an existing three-phase solid-state transformer where each phase has 1 module.

[0047] Figure 11 The waveform diagram for the front-end of an existing three-phase solid-state transformer using zero-sequence voltage control;

[0048] Figure 12 This is a schematic diagram of the structure of the phase-shift control method of the present invention applied to a non-isolated high-frequency cascaded power supply module;

[0049] Figure 13 This is a schematic diagram of an application embodiment of the phase-shifting control method of the present invention applied to a power supply device with an energy storage battery;

[0050] Figure 14 A schematic diagram of the structure of the phase-shifting control method of the present invention applied to a high-voltage DC to low-voltage DC conversion system. Detailed Implementation

[0051] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0052] In describing the elements / components / etc. described and / or illustrated herein, the terms “a,” “an,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc. The terms “comprising,” “including,” and “having” are used to indicate an open-ended inclusion and to mean that additional elements / components / etc. may exist in addition to those listed. Relative terms, such as “upper” or “lower,” may be used in the embodiments to describe the relative relationship of one component of the icon to another component. It is understood that if the device of the icon is flipped so that it is upside down, the component described as being on the “upper” side will become the component on the “lower” side. Furthermore, the terms “first,” “second,” etc., in the claims are used only as illustrative marks and are not intended to limit the number of objects to which they apply.

[0053] This invention combines the advantages of existing high-frequency cascaded converters and proposes a phase-shift control method for power supply modules applied to high-frequency cascaded converters. The following section will use... Figure 2 The phase-shift control method will be explained using the high-frequency cascaded power supply module shown as an example.

[0054] like Figure 2 As shown, a power supply module 100 of the present invention may include N inverter units 10, where N is a positive integer greater than or equal to 3. Furthermore, the N inverter units 10 can output N AC-side voltages (e.g., V). PA V PB V PC However, this is not a limitation), and the N inverter units 10 are correspondingly coupled to N high-frequency AC terminals 20, which are cascaded and connected to a subsequent rectifier circuit 30. The power supply module 100 may also include a controller (not shown in the figure), which can be configured to perform phase-shift control, for example, to perform... Figure 3 The phase-shift control method shown.

[0055] Reference Figure 2 and Figure 4 ,like Figure 3 As shown, the phase-shift control method of the power supply device of the present invention mainly includes:

[0056] Step S31: Set at least two phase shifting sequences (e.g.) Figure 4The three control modes correspond to the three phase shift sequences, but are not limited to these, where the N AC side voltages (e.g., V) of the N inverter units 10 are... pA V pB V pC (However, not limited to this) the phase sequence numbers in the at least two phase shifting sequences are all different.

[0057] Step S32: In one switching cycle, control the N AC-side voltages (e.g., V) of the N inverter units 10. pA V pB V pC ) to each other in the first phase shifting order of the at least two phase shifting sequences (e.g. Figure 4 One of the three control modes in the process) Phase shift first angle.

[0058] Step S33: In another switching cycle, control the N AC-side voltages (e.g., V) of the N inverter units 10. pA V pB V pC ) each other in the second phase shifting order of the at least two phase shifting orders (e.g. Figure 4 (One of the three control modes) shifts the first angle.

[0059] In this invention, the duration of each phase shift sequence is at least m switching cycles, where m is a positive integer greater than or equal to 1. Preferably, during phase shift control, for example, N phase shift sequences can be set, and the controller can control the N AC-side voltages of the N inverter units to sequentially rotate phases according to the N phase shift sequences. Furthermore, in the N phase shift sequences, the phase arrangement sequence number of each inverter unit is different in each of the N phase shift sequences.

[0060] exist Figure 2 In the illustrated embodiment, N equals 3, thus providing a three-phase power supply module 100. However, it is understood that N may be other numbers in other embodiments, which is not intended to limit the invention.

[0061] More specifically, Figure 2 The three-phase power supply module 100 shown includes three inverter units 10, three high-frequency AC terminals 20, a post-stage rectifier circuit 30, three pre-stage single-phase rectifier circuits 40, three intermediate DC bus capacitors 50 (i.e., DC-link), and a controller (not shown). The AC terminals of the three pre-stage single-phase rectifier circuits 40 are electrically coupled to a three-phase AC power supply, which can provide voltage V respectively. gA V gB V gCThe three inverter units 10 respectively output three AC-side voltages, for example, output AC-side voltage V. pA V pB V pC Furthermore, the three front-end rectifier circuits 40 are each connected to the inverter unit 10 one-to-one through an intermediate DC bus capacitor 50, and the DC input voltages of the three inverter units 10 are respectively V dcA V dcB V dcC The three high-frequency AC terminals 20 are correspondingly coupled to the three inverter units 10. The subsequent rectifier circuit 30 is connected to the cascaded three high-frequency AC terminals 20. The controller (not shown) can be configured to perform phase-shift control, for example, to perform... Figure 3 The phase-shift control method shown.

[0062] Preferably, the three-phase power supply module 100 may further include three isolation transformers 60, which are correspondingly disposed between the three inverter units 10 and the three high-frequency AC terminals 20, thereby forming a three-phase high-frequency cascaded isolated power supply module. Figure 2 In the illustrated embodiment, each isolation transformer 60 includes a primary winding and a secondary winding, the primary winding being connected to the inverter unit 10 and the secondary winding being connected to the high-frequency AC terminal 20.

[0063] Preferably, the three front-stage single-phase rectifier circuits 40 can be single-phase AC-DC circuits. The three high-frequency AC terminals 20 can be the output terminals of the secondary winding of the isolation transformer 60, and each can have a voltage V. sA V sB V sC The three high-frequency AC terminals 20 (i.e., the output terminals of the secondary windings of the three isolation transformers 60) are cascaded and then connected to the subsequent rectifier circuit 30.

[0064] In this embodiment, when the three-phase power supply module 100 performs phase shift control, it does so by controlling the AC side voltage (V) on the primary side of the three isolation transformers 60. pA V pB V pC The controller of the three-phase power supply module 100 performs phase shift control in rotation. For example, it sets three phase shift sequences and controls the three AC side voltages of the three inverter units to rotate in rotation with each other in the three phase shift sequences. Figure 2 The three-phase power supply module 100 shown has three primary-side AC-side voltages V pA V pB V pCWith three phase-shift control modes, for example Figure 4 The modes 1, 2, and 3 shown correspond to a phase-shift control sequence. Specifically, as... Figure 4 As shown, in mode 1, V pA Lag V pC First angle, V pB Lag V pA First perspective; in mode 2, V pC Lag V pB First angle, V pA Lag V pC First perspective; in mode 3, V pB Lag V pA First angle, V pC Lag V pB First angle. Therefore, the AC side voltage V on each primary side. pA V pB V pC The phase arrangement sequence is different in these three phase-shift control modes, and the AC side voltage V on the three primary sides of each mode is different. pA V pB V pC The phase shifting angles are sequentially delayed. The duration of each mode (i.e., phase shift sequence) can be at least m (m≥1) switching cycles. These three phase shifting control modes can be sequentially rotated within 3*m switching cycles. The switching cycle here can, for example, refer to the switching cycle of the inverter unit 10 on the primary side, and also the high-frequency AC side voltage V on the primary side. pA V pB V pC The cycle time. The alternating phase shift control method of this embodiment can be extended to N high-frequency cascaded converters.

[0065] The simulation waveform using the alternating phase-shifting control method is as follows: Figure 5 As shown. Figure 5 The phase-shift control mode cycles once every switching cycle. Through this phase-shift control, the input current i changes every three switching cycles. LrA i LrB i LrC The effective values ​​are basically equal when the input voltage V of the three inverter units 10 is approximately equal. dcA V dcB V dcC When the input power is equal, the input power is equal. Therefore, this invention eliminates the need for closed-loop controller design; it achieves power sharing among the three phases of a three-phase power supply module simply through open-loop phase-shifting control, making it easy to implement.

[0066] Furthermore, the phase shifting in this invention can also employ a partial mode of shifting, for example, using only one mode. Figure 4 The alternation between Mode 1 and Mode 2 can also achieve a certain degree of power balance among the three phases.

[0067] like Figure 6 As shown, it illustrates the relationship between the phase shift angle and the gain in the phase shift control method of the present invention. Figure 6 It can be seen that as the phase shift angle increases, the gain gradually decreases, thus achieving wide-range control of the output voltage. Furthermore, in this invention, the larger the first phase shift angle, the smaller the output voltage of the subsequent rectifier circuit. Although... Figure 6 The phase shift angle and gain shown are linearly related, but in practice, a perfect linear relationship may not be required; for example, an approximate linear relationship can be achieved. Furthermore, the size of the first angle can be set according to actual needs, and this invention does not impose any limitations on this.

[0068] The phase-shift control method of this invention not only achieves a wide range of voltage output and is less prone to ZVS loss, but also ensures high system efficiency with efficiency largely unaffected by voltage regulation. Furthermore, in the three-phase power supply module of this invention, the primary currents of the three phases are completely identical, resulting in no second-harmonic power fluctuations in the secondary current. This eliminates the need for any measures to suppress second-harmonic power in the subsequent stages, and also eliminates second-harmonic power fluctuations in the subsequent DC-DC isolation circuit, thereby improving the efficiency of the subsequent stages.

[0069] like Figure 7 The diagram illustrates the structure of a three-phase power supply system 700 based on the three-phase power supply module of the present invention. The three-phase power supply system 700 includes three three-phase power supply modules 71, and the AC sides of the corresponding front-end rectifier circuits in these three three-phase power supply modules 71 are cascaded and connected to a three-phase AC power supply 72. The three-phase AC power supply 72 can be, for example, a three-phase power grid, which may include phase A 721, phase B 722, and phase C 723, wherein phase A 721, phase B 722, and phase C 723 may each have a voltage V. gA V gB V gC .exist Figure 7 In the illustrated embodiment, each of the three-phase power supply modules 71 may be, for example, as shown below. Figure 2 The three-phase high-frequency cascaded isolated power supply module shown can be further cascaded with corresponding phases between modules to form a new SST topology.

[0070] exist Figure 7In the illustrated embodiment, the three-phase inputs of the three-phase power supply modules 71 can be cascaded and connected to the three-phase power grid, while the outputs of all three-phase power supply modules 71 are connected in parallel. Each three-phase power supply module 71 may contain a controller (not shown in the figure), and the three-phase power supply system 700 also includes a main controller 73, mainly used as the overall monitoring unit. The controllers of each three-phase power supply module 71 are connected to each other via communication lines, wherein the three phases can be star-connected or delta-connected. Compared with the existing SST, the number of modules in this invention is reduced, as are the number of controllers and communication loops. Furthermore, the three-phase modules are already coordinated internally, eliminating the need for additional communication lines between the three phases, thus reducing the complexity of coordination between the three phases of the system.

[0071] In existing technologies, each phase of a three-phase isolation module needs to handle single-phase power, which exhibits second-harmonic frequency fluctuations, thus causing corresponding DC-link (i.e., Figure 2 China V dcA V dcB V dcC The present invention addresses voltage fluctuations at the output stage (AC-DC) or power fluctuations in the subsequent DC-DC isolation circuit. However, due to the high-frequency cascading of the three-phase power supply modules, the subsequent DC-DC isolation circuit does not contain second-harmonic current. Second-harmonic power fluctuations can be absorbed by the DC-Link, thus avoiding the adverse effects of second-harmonic power on the efficiency of the subsequent stage. When all second-harmonic power is on the DC-Link, the DC-Link voltage will experience significant second-harmonic fluctuations, leading to overvoltage or undervoltage. When the DC-Link voltage is undervoltage, the modulation ratio of the preceding AC-DC circuit may be too high (the modulation ratio must be less than 1), causing the preceding stage to malfunction. When the DC-Link voltage is overvoltage, it may cause damage to circuit components. Therefore, the high-frequency cascaded isolated three-phase power supply module circuit of the present invention can further perform inter-phase voltage equalization control on the output voltage of the preceding stage, thereby suppressing the impact of second-harmonic power on DC-Link voltage fluctuations.

[0072] like Figure 8 As shown, it illustrates the phase-to-phase voltage equalization control block diagram of the front-stage rectifier circuit of the present invention. Where θ A θ B θ C AC input V gA V gB V gC phase, V bA V bB V bC These are the bridge arm input voltages of the preceding single-phase rectifier circuit. Figure 8The “common-mode voltage controller” marked in the text controls the three-phase average DC-Link voltage. It generally adopts proportional-integral control. The output of the controller is multiplied by the phase of the grid voltage of each phase as the command for the current controller of each phase. Figure 8 The section labeled "Differential Mode Voltage Controller" is the phase-to-phase voltage equalization control loop. It generates a zero-sequence voltage V0, thereby suppressing the second harmonic fluctuation of the DC-Link voltage. The control effect diagram is shown below. Figure 9B As shown.

[0073] like Figure 9A and Figure 9B The figures show the waveforms of DC-Link voltage fluctuations when the front-stage rectifier circuit of the present invention does not employ inter-phase voltage equalization control and the waveforms after the front-stage rectifier circuit employs inter-phase voltage equalization control. (Comparison) Figure 9A and Figure 9B As can be seen, after adopting phase-to-phase voltage equalization control, although the second harmonic power is absorbed by the DC-Link, Figure 9B The peak value of the second harmonic fluctuation of the DC-Link voltage is significantly reduced, while the trough value remains basically unchanged, which does not affect the normal operation of the system.

[0074] The present invention is as follows Figure 2 The isolated three-phase power supply module circuit shown is similar to an existing SST circuit with one module (cell) per phase (its topology is as follows). Figure 10 For comparison (as shown), the existing SST circuit's front-end also uses... Figure 8 The control block diagram shown is illustrated in Figure 11, where the waveform of the front-end stage using zero-sequence voltage control is shown in Figure 11. (Comparison) Figure 11 and Figure 9B It can be seen that the structure and phase-shift control method of the present invention, combined with the phase-to-phase voltage equalization control of the preceding stage, further ensures the three-phase resonant current i while ensuring that the DC-Link voltage is neither over-voltage nor under-voltage. LrA i LrB i LrC Completely consistent, enabling automatic current sharing in subsequent stages. And... Figure 11 The middle stage circuit contains a double frequency current, which affects the efficiency of the subsequent stage.

[0075] The embodiments of the power supply module provided by this invention are not limited to those described above. Figure 2 The embodiments shown are not limited to the power supply system provided by the present invention. Figure 7 The embodiment shown. Although in Figure 7The illustrated embodiment shows the structure of a three-phase power supply system 700 including three three-phase power supply modules 71. However, it is understood that the structure of the power supply system provided by the present invention is not limited thereto, and may include at least two power supply modules. Furthermore, the output terminals of the at least two power supply modules may be independent output terminals or connected in parallel to form a common DC output terminal. The input terminals of the at least two power supply modules may be cascaded, independent input terminals, or connected in parallel; these are not intended to limit the present invention.

[0076] The high-frequency isolated three-phase power supply module provided by this invention, which, through cascading of pre-stage components to form an SST, can be applied to fast charging stations, photovoltaic power plants, data centers, energy storage, and microgrids. The phase-shift control method of the power supply module of this invention is also not limited to the embodiments listed below.

[0077] (1) Three-input non-isolated high-frequency cascaded power supply module

[0078] The phase-shifting control method of the present invention can also be applied to a non-isolated high-frequency cascaded power supply module 100-1, the topology of which is as follows: Figure 12 As shown. With Figure 2 Unlike the illustrated embodiment, the power supply module 100-1 in this embodiment does not have an isolation converter, and each high-frequency AC terminal 20 is the output terminal of each inverter unit 10 (e.g., a DC-AC circuit). In this embodiment, the DC input voltage V dcA V dcB and V dcC The DC-AC circuit outputs a high-frequency AC voltage V. pA V pB and V pC These high-frequency AC voltages V pA V pB and V pC Without the need for an isolation transformer, it can be directly cascaded to the output of the subsequent rectifier circuit 30 (e.g., a subsequent AC-DC circuit). This topology, combined with alternating phase-shift control, can be applied to situations where different batteries or other independent power sources supply the same load. By cascading the inverter circuit at high frequency on the AC side and employing alternating phase-shift control, power balance between the battery and the power source can be ensured.

[0079] (2) Application examples of power supply modules with energy storage batteries

[0080] The phase-shifting control method of the present invention can also be applied to an application embodiment of a power supply module 100-2 with an energy storage battery, the topology of which is as follows: Figure 13As shown. In this embodiment, the power supply module 100-2 further includes multiple energy storage batteries 80, which are respectively connected to the DC terminals of multiple inverter units 10. By using multiple energy storage batteries 80 to supply power to the load, the output power of the batteries can be automatically balanced.

[0081] (3) Examples of MVDC-LVDC conversion systems

[0082] The phase-shifting control method of the present invention can also be applied to the structure of a high-voltage DC to low-voltage DC conversion system, the topology of which is as follows: Figure 14 As shown, this system can be applied to high-voltage DC to low-voltage DC conversion applications. In this embodiment, the conversion system includes N power supply modules 141. The corresponding input terminals of all power supply modules 141 are cascaded and connected to a three-phase DC power supply. The output voltage of each power supply module 141 is independent, for example, each outputs a voltage V. o1 V o2 ... V oN In other embodiments, the outputs of these power supply modules 141 may be further connected in parallel to form a common DC bus output. The corresponding inputs of these power supply modules 141 may also be connected in parallel or independently, and are not limited to cascading.

[0083] The proposed phase-shifting control method for high-frequency cascaded modules achieves wide-range, high-efficiency output and power-averaging control. By combining a pre-stage AC-DC differential voltage controller with zero-sequence voltage injection, this invention suppresses second-harmonic frequency fluctuations in the DC-Link voltage.

[0084] The three-phase isolated three-phase power supply module proposed in this invention can cancel the second harmonic fluctuation of the secondary voltage and eliminate the current imbalance of the three-phase resonant tank by cascading the three phases at high frequency.

[0085] The SST proposed in this invention is based on a three-phase power supply module with three-phase isolation. Each power supply module includes a controller and is connected through a communication line, which reduces the number of modules and controllers.

[0086] Exemplary embodiments of the present invention have been specifically illustrated and described above. It should be understood that the present invention is not limited to the disclosed embodiments; rather, the present invention is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. A phase-shift control method for a power supply module, characterized in that, The power supply module includes N inverter units, each outputting N AC-side voltages, where N is a positive integer greater than or equal to 3. Each of the N inverter units is coupled to N high-frequency AC terminals, which are cascaded and connected in parallel to a subsequent rectifier circuit. The phase-shift control method includes: At least two phase shifting sequences are provided, wherein the phase arrangement numbers of the N AC side voltages of the N inverter units are all different in the at least two phase shifting sequences; During a switching cycle, the N AC-side voltages of the N inverter units are controlled to shift each other by a first angle in a first phase shift sequence of at least two phase shift sequences; In another switching cycle, the N AC-side voltages of the N inverter units are controlled to shift each other by the first angle in the second phase shift sequence of the at least two phase shift sequences.

2. The phase-shift control method for the power supply module according to claim 1, characterized in that, The duration of each phase shift sequence is at least m switching cycles, where m is a positive integer greater than or equal to 1.

3. The phase-shift control method for the power supply module according to claim 1, characterized in that, When performing phase-shift control, N phase-shift sequences are set, and the N AC-side voltages of the N inverter units are controlled to take turns shifting phases in the N phase-shift sequences.

4. The phase-shift control method for the power supply module according to claim 3, characterized in that, In the N phase shifting sequences, the phase arrangement number of each inverter unit is different in the N phase shifting sequences.

5. The phase-shift control method for the power supply module according to claim 1, characterized in that, The power supply module also includes N front-end rectifier circuits, which are connected to the DC terminals of the N inverter units through an intermediate DC bus capacitor, and output N front-end output voltages to the N inverter units accordingly. The phase-shift control method further includes: Phase-to-phase voltage equalization control is performed on the N front-end output voltages.

6. The phase-shift control method for the power supply module according to claim 1, characterized in that, The power supply module also includes N energy storage batteries, which are respectively connected to the DC terminals of the N inverter units.

7. The phase-shift control method for a power supply module according to any one of claims 1 to 6, characterized in that, The power supply module also includes N isolation transformers, which are respectively set between the N inverter units and the N high-frequency AC terminals; the N isolation transformers include N primary windings and N secondary windings, the N primary windings are respectively connected to the N inverter units, and the N secondary windings are respectively connected to the N high-frequency AC terminals.

8. The phase-shift control method for the power supply module according to claim 7, characterized in that, When performing phase-shift control, the AC side voltages on the primary side of the N isolation transformers are rotated and phase-shifted.

9. The phase-shift control method for the power supply module according to claim 1, characterized in that, The larger the first angle, the smaller the output voltage of the subsequent rectifier circuit.

10. A three-phase power supply module, characterized in that, Include: Three single-phase rectifier circuits are provided, with their AC terminals electrically coupled to a three-phase AC power supply. Three intermediate DC bus capacitors; The three inverter units output three AC side voltages, and the front-end single-phase rectifier circuit is connected to the inverter units one by one through the intermediate DC bus capacitor. Three high-frequency AC terminals are correspondingly coupled to the three inverter units; A subsequent rectifier circuit is connected to the three cascaded high-frequency AC terminals; A controller, configured to perform phase-shift control, includes: At least two phase shifting sequences are provided, wherein the phase arrangement numbers of the three AC side voltages of the three inverter units are all different in the at least two phase shifting sequences; During a switching cycle, the three AC side voltages of the three inverter units are controlled to be phase-shifted relative to each other by a first phase-shifting order of at least two phase-shifting sequences by a first angle; In another switching cycle, the three AC-side voltages of the three inverter units are controlled to shift each other by the first angle in the second phase shift sequence of the at least two phase shift sequences.

11. The three-phase power supply module according to claim 10, characterized in that, When performing phase-shift control, the controller sets three phase-shift sequences, and controls the three AC side voltages of the three inverter units to take turns shifting phases in the three phase-shift sequences.

12. The three-phase power supply module according to claim 11, characterized in that, The duration of each phase shift sequence is at least m switching cycles, where m is a positive integer greater than or equal to 1.

13. The three-phase power supply module according to claim 11, characterized in that, In the three phase shifting sequences, the phase sequence number of each inverter unit is different in the three phase shifting sequences.

14. The three-phase power supply module according to claim 10, characterized in that, in, The controller is also used to perform phase-to-phase voltage equalization control on the three output voltages of the three front-stage single-phase rectifier circuits.

15. The three-phase power supply module according to any one of claims 10 to 14, characterized in that, Also includes: Three isolation transformers are respectively installed between the three inverter units and the three high-frequency AC terminals.

16. The three-phase power supply module according to claim 15, characterized in that, in, When performing phase-shift control, the controller performs alternating phase-shift control on the AC side voltage of the primary side of the three isolation transformers.

17. A power supply system, characterized in that, include: At least two three-phase power supply modules as described in any one of claims 10 to 16.

18. The power supply system according to claim 17, characterized in that, The output terminals of the at least two three-phase power supply modules are either independent output terminals or connected in parallel to form a common DC output terminal.

19. The power supply system according to claim 17, characterized in that, The input terminals of the at least two three-phase power supply modules are either cascaded, independent, or connected in parallel.

20. The power supply system according to claim 17, characterized in that, The power supply system is a three-phase power supply system, including three three-phase power supply modules, and the AC side of the corresponding front-end rectifier circuits in the three three-phase power supply modules are cascaded and connected to each phase of the three-phase AC power supply.

21. The power supply system according to claim 19, characterized in that, The controllers of each of the three-phase power supply modules are connected via communication lines.

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