Five-level fractal converter

Abstract

The invention discloses a five-level fractal converter, and relates to the technical field of AC / DC converters. The five-level fractal converter comprises: an inversion module comprising a five-level inverter, the five-level inverter being used for outputting an alternating current signal, the alternating current signal comprising a first harmonic signal in a higher harmonic interval; the harmonic generation module comprises at least one harmonic generation inverter, and the harmonic generation inverter is used for outputting a corresponding second harmonic signal according to the first harmonic signal; the first input end of the fractal connector module is electrically connected with the alternating current side of the five-level inverter, at least one second input end of the fractal connector module is correspondingly and electrically connected with the alternating current side of the at least one harmonic generation inverter, and the output end of the fractal connector module is electrically connected with the alternating current output port; the second harmonic signal is used to compensate the first harmonic signal within the fractal connector module. According to the embodiment of the invention, the harmonic signal of the five-level inverter can be compensated.

Description

Technical Field

[0001] This application belongs to the field of AC / DC converter technology, and particularly relates to a five-level fractal converter. Background Technology

[0002] With the transformation of the global energy structure and the widespread application of new energy sources, especially wind and solar power, power electronics technology plays an increasingly important role in new energy power generation systems. As a core component of these systems, the performance of inverters directly affects the operating efficiency, stability, and energy conversion quality of the power system.

[0003] With the booming development of new energy power generation, the demand for high-power power electronic converters in new power systems is increasing. Five-level converters are a commonly used AC / DC converter. Compared to two-level / three-level converters, five-level converters can provide more voltage steps, thus possessing better harmonic characteristics and a higher equivalent switching frequency, and can adapt to higher voltage levels.

[0004] However, in existing AC / DC converter technologies, the switching frequency of five-level converters is relatively high, resulting in high losses and heat generation in the switching devices, leading to low overall output capacity and high cost per unit capacity. Therefore, how to effectively reduce the switching frequency of five-level inverters and improve the overall output capacity of the converter has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application provides a five-level fractal converter that can effectively compensate for the harmonic signals of the five-level fractal converter, thereby helping to reduce the switching frequency of the five-level inverter and improve the overall output capacity of the converter.

[0006] In a first aspect, embodiments of this application provide a five-level fractal converter, which includes:

[0007] The inverter module includes a five-level inverter, the DC side of which is electrically connected to the first DC power supply port. The five-level inverter is used to output an AC signal, which includes a first harmonic signal in the higher harmonic range.

[0008] The harmonic generation module includes at least one harmonic generation inverter. The DC side of any harmonic generation inverter is electrically connected to the corresponding second DC power supply port. The corresponding harmonic generation inverter is used to output a corresponding second harmonic signal according to the first harmonic signal.

[0009] The fractal connector module has a first input terminal electrically connected to the AC side of a five-level inverter, at least one second input terminal electrically connected to the corresponding AC side of at least one harmonic generating inverter, and an output terminal electrically connected to an AC output port.

[0010] The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module.

[0011] In some possible implementations, the number of harmonic generation inverters in the harmonic generation module is 1;

[0012] The alternating current signal includes n first harmonic signals corresponding to n higher harmonic intervals, where n is greater than or equal to 1 and n is a positive integer.

[0013] The harmonic generation inverter is used to output n second harmonic signals, and the n second harmonic signals correspond one-to-one with the n first harmonic signals.

[0014] In some possible implementations, the number of harmonic generation inverters in the harmonic generation module is n, where n is greater than 1 and n is a positive integer;

[0015] The AC sides of the n harmonic generation inverters are electrically connected to the n second input terminals of the fractal connector module, respectively.

[0016] The switching frequency of the switching device of the i-th harmonic generator inverter is greater than the switching frequency of the switching device of the (i-1)-th harmonic generator inverter, 1 < i ≤ n, where i is a positive integer;

[0017] The alternating current signal includes n first harmonic signals corresponding to n higher harmonic intervals. The n harmonic generator inverter is used to output n second harmonic signals, and the n second harmonic signals correspond one-to-one with the n first harmonic signals.

[0018] In some possible implementations, the switching frequency of any harmonic generating inverter is greater than the switching frequency of a five-level inverter.

[0019] In some possible implementations, the AC side of the five-level inverter includes three single-phase AC output terminals; the five-level inverter includes at least one supporting capacitor and a three-phase inverter bridge, the three-phase inverter bridge including three single-phase inverter bridges corresponding one-to-one with the three single-phase AC output terminals;

[0020] The single-phase inverter bridge includes bridge arm branches located between the first DC power supply ports;

[0021] The bridge arm branch includes the bridge arm midpoint, which is electrically connected to the corresponding single-phase AC output terminal.

[0022] At least one supporting capacitor is connected in series between the first DC power supply ports.

[0023] In some possible implementations, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node.

[0024] At least one supporting capacitor includes: a first supporting capacitor, a second supporting capacitor, a third supporting capacitor and a fourth supporting capacitor sequentially disposed between the first DC power supply ports, the first supporting capacitor and the second supporting capacitor being electrically connected to the seventh node, the second supporting capacitor and the third supporting capacitor being electrically connected to the eighth node, and the third supporting capacitor and the fourth supporting capacitor being electrically connected to the ninth node.

[0025] At least one first diode is provided between the first node and the seventh node, at least one second diode is provided between the seventh node and the fourth node, at least one third diode is provided between the second node and the eighth node, at least one fourth diode is provided between the eighth node and the fifth node, at least one fifth diode is provided between the third node and the ninth node, and at least one sixth diode is provided between the ninth node and the sixth node.

[0026] In some possible implementations, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node.

[0027] At least one supporting capacitor includes: a first supporting capacitor, a second supporting capacitor, a third supporting capacitor and a fourth supporting capacitor sequentially disposed between the first DC power supply ports, the first supporting capacitor and the second supporting capacitor being electrically connected to the seventh node, the second supporting capacitor and the third supporting capacitor being electrically connected to the eighth node, and the third supporting capacitor and the fourth supporting capacitor being electrically connected to the ninth node.

[0028] A first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode are connected in series between the first node and the sixth node; a seventh diode, an eighth diode, a ninth diode, and a tenth diode are connected in series between the second node and the fifth node; and an eleventh diode and a twelfth diode are connected in series between the third node and the fourth node.

[0029] The anode of the first diode is electrically connected to the seventh node, the anode of the second diode is electrically connected to the anode of the seventh diode, the anode of the third diode is electrically connected to the eighth node, the anode of the fourth diode is electrically connected to the anode of the ninth diode, the anode of the fifth diode is electrically connected to the ninth node, and the anode of the eighth diode is electrically connected to the anode of the eleventh diode.

[0030] In some possible implementations, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node.

[0031] At least one supporting capacitor includes: a first supporting capacitor and a second supporting capacitor sequentially disposed between the first DC power supply ports, the first supporting capacitor and the second supporting capacitor being electrically connected to the seventh node;

[0032] At least one switching unit is provided between the second node and the seventh node, and at least one switching unit is provided between the seventh node and the fifth node;

[0033] At least one capacitor is provided between the third node and the fourth node.

[0034] In some possible implementations, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node.

[0035] At least one first capacitor is provided between the first node and the sixth node, at least one second capacitor is provided between the second node and the fifth node, and at least one third capacitor is provided between the third node and the fourth node.

[0036] In some possible implementations, the single-phase inverter bridge includes a first switching unit, a second switching unit, a third switching unit, and a fourth switching unit connected in series between the first DC power supply ports. The first and second switching units are electrically connected to a first node, the second and third switching units are electrically connected to the midpoint of the bridge arm, and the third and fourth switching units are electrically connected to a second node.

[0037] At least one supporting capacitor includes: a first supporting capacitor, a second supporting capacitor, a third supporting capacitor and a fourth supporting capacitor sequentially disposed between the first DC power supply ports, wherein the first supporting capacitor and the second supporting capacitor are electrically connected to a third node, the second supporting capacitor and the third supporting capacitor are electrically connected to a fourth node, and the third supporting capacitor and the fourth supporting capacitor are electrically connected to a fifth node.

[0038] The single-phase inverter bridge also includes a fifth switching unit, a sixth switching unit, a seventh switching unit, and an eighth switching unit;

[0039] The first end of the fifth switch unit is electrically connected to the first node, the second end of the fifth switch unit is electrically connected to the third node, the first end of the sixth switch unit is electrically connected to the first end of the seventh switch unit, the second end of the sixth switch unit is electrically connected to the fourth node, the second end of the seventh switch unit is electrically connected to the midpoint of the bridge arm, the first end of the eighth switch unit is electrically connected to the fifth node, and the second end of the eighth switch unit is electrically connected to the second node.

[0040] In some possible implementations, the single-phase inverter bridge includes a first switching unit, a second switching unit, a third switching unit, and a fourth switching unit connected in series between the first DC power supply ports. The first and second switching units are electrically connected to a first node, the second and third switching units are electrically connected to the midpoint of the bridge arm, and the third and fourth switching units are electrically connected to a second node.

[0041] At least one supporting capacitor includes: a first supporting capacitor and a second supporting capacitor sequentially disposed between the first DC power supply ports, the first supporting capacitor and the second supporting capacitor being electrically connected to a third node;

[0042] The single-phase inverter bridge also includes a first capacitor, a second capacitor, a fifth switching unit, a sixth switching unit, a seventh switching unit, and an eighth switching unit; the first terminal of the first capacitor is electrically connected to the first node, the second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor, and the second terminal of the second capacitor is electrically connected to the second node; the first terminal of the fifth switching unit is electrically connected to the first terminal of the sixth switching unit, the first terminal of the fifth switching unit is electrically connected to the second terminal of the first capacitor, the second terminal of the sixth switching unit is electrically connected to the midpoint of the bridge arm, the first terminal of the seventh switching unit is electrically connected to the first terminal of the eighth switching unit, the second terminal of the seventh switching unit is electrically connected to the second terminal of the first supporting capacitor, and the second terminal of the eighth switching unit is electrically connected to the second terminal of the first capacitor.

[0043] In some possible implementations, the single-phase inverter bridge includes multiple switching units, each of which includes multiple semiconductor power switching units; the semiconductor power switching units include at least one of IGCT, IGBT, IEGT, and MOSFET.

[0044] In any given switching unit, multiple semiconductor power switching units are connected in series.

[0045] And / or, multiple semiconductor power switching units in any switching unit are connected in parallel with each other.

[0046] In some possible implementations, the semiconductor switching unit in any switching unit includes an IGCT;

[0047] The five-level inverter also includes a clamping circuit disposed between the first DC power supply ports.

[0048] In some possible implementations, the fractal connector module includes: a first winding, at least one second winding, and a third winding;

[0049] The first winding, at least one second winding, and the third winding are coupled together;

[0050] The first winding is electrically connected to the AC side of the five-level inverter, at least one second winding is electrically connected to the AC side of at least one harmonic generating inverter, and the third winding is electrically connected to the AC output port.

[0051] In some possible implementations, the first winding includes a delta winding, any second winding includes a star winding or a delta winding, and the third winding includes a star winding or a delta winding.

[0052] In some possible implementations, the fractal connector module includes at least one fourth winding and at least one fifth winding;

[0053] The fourth winding is coupled to the corresponding fifth winding, the fourth winding is electrically connected to the AC side of the five-level inverter, the fifth winding is electrically connected to the AC side of the corresponding harmonic generation inverter, and the AC side of the five-level inverter is electrically connected to the AC output port.

[0054] In some possible implementations, the fractal connector module includes: at least one connecting component;

[0055] The AC side of the five-level inverter is electrically connected to the AC side of the corresponding harmonic generation inverter through a connecting component, so that the AC side of the five-level inverter and the AC side of the corresponding harmonic generation inverter are connected in parallel.

[0056] The AC side of the five-level inverter is electrically connected to the AC output port.

[0057] In some possible implementations, the fractal connector module includes at least one series transformer;

[0058] The first input terminal of the series transformer is electrically connected to the AC side of the five-level inverter, the second input terminal of the series transformer is electrically connected to the AC side of the corresponding harmonic generation inverter, and the output terminal of the series transformer is electrically connected to the AC output port.

[0059] In some possible implementations, the series transformer includes: a first transformer, a second transformer, and a third transformer;

[0060] The first terminal of the first transformer is electrically connected to the first terminal of the AC side of the five-level inverter; the second terminal of the first transformer is electrically connected to the first terminal of the AC output port; the third terminal of the first transformer is electrically connected to the neutral point or ground terminal; and the fourth terminal of the first transformer is electrically connected to the first terminal of the AC side of the harmonic generation inverter.

[0061] The first terminal of the second transformer is electrically connected to the second terminal of the AC side of the five-level inverter; the second terminal of the second transformer is electrically connected to the second terminal of the AC output port; the third terminal of the second transformer is electrically connected to the neutral point or ground terminal; and the fourth terminal of the second transformer is electrically connected to the second terminal of the AC side of the harmonic generation inverter.

[0062] The first terminal of the third transformer is electrically connected to the third terminal of the AC side of the five-level inverter. The second terminal of the third transformer is electrically connected to the third terminal of the AC output port. The third terminal of the third transformer is electrically connected to the neutral point or ground terminal. The fourth terminal of the third transformer is electrically connected to the third terminal of the AC side of the harmonic generation inverter.

[0063] In some possible implementations, the series transformer includes: a first single-phase winding, a second single-phase winding, a third single-phase winding, and a sixth winding;

[0064] The first single-phase winding, the second single-phase winding, and the third single-phase winding are electrically coupled to the sixth winding;

[0065] The first end of the first single-phase winding is electrically connected to the first end of the AC side of the five-level inverter, and the second end of the first single-phase winding is electrically connected to the first end of the AC output port.

[0066] The first end of the second single-phase winding is electrically connected to the second end of the AC side of the five-level inverter, and the second end of the second single-phase winding is electrically connected to the second end of the AC output port.

[0067] The first end of the third single-phase winding is electrically connected to the third end of the AC side of the five-level inverter, and the second end of the third single-phase winding is electrically connected to the third end of the AC output port.

[0068] The sixth winding is electrically connected to the first terminal, the second terminal, and the third terminal of the AC side of the corresponding harmonic generator inverter.

[0069] In some possible implementations, a first filter is provided, with its first end electrically connected to the AC side of a five-level inverter, and its second end electrically connected to the first input end of a fractal connector module.

[0070] And / or, a second filter, the first end of which is electrically connected to the AC side of the corresponding harmonic generation inverter, and the second end of which is electrically connected to the corresponding second input end in the fractal connector module.

[0071] This application provides a five-level fractal converter, which includes an inverter module, a harmonic generation module, and a fractal connector module. The inverter module includes a five-level inverter, the DC side of which is electrically connected to a first DC power supply port. The five-level inverter outputs an AC signal, which includes a first harmonic signal within the higher harmonic range. The harmonic generation module includes at least one harmonic generation inverter, the DC side of which is electrically connected to a corresponding second DC power supply port. This harmonic generation inverter outputs a corresponding second harmonic signal based on the first harmonic signal. The first input terminal of the fractal connector module is electrically connected to the AC side of the five-level inverter. At least one second input terminal of the fractal connector module is electrically connected to the corresponding AC side of at least one harmonic generation inverter. The output terminal of the fractal connector module is electrically connected to an AC output port. The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module.

[0072] As described above, the harmonic generation inverter generates a second harmonic signal based on the first harmonic signal generated by the five-level inverter, and outputs the second harmonic signal to the fractal connector module. This allows the second harmonic signal to compensate for the first harmonic signal within the fractal connector module, reducing or even eliminating harmonics in the output electrical signal from the converter to the AC output port. Therefore, based on the harmonic compensation functions of the harmonic generation module and the fractal connector module, the switching devices of the five-level inverter can operate at a lower switching frequency with lower switching device losses. This lower switching frequency operation allows for increased output capacity, significantly reducing the cost per unit capacity of the inverter while effectively ensuring the reliability and performance of the output signal. Attached Figure Description

[0073] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0074] Figure 1 This is a schematic diagram of the structure of a five-level fractal converter provided in an embodiment of this application;

[0075] Figure 2 This is a schematic diagram of the structure of a five-level fractal converter provided in another embodiment of this application;

[0076] Figure 3 This is a schematic diagram of the structure of a five-level inverter provided in one embodiment of this application;

[0077] Figure 4 This is a schematic diagram of the structure of a five-level inverter provided in another embodiment of this application;

[0078] Figure 5 This is a schematic diagram of the structure of a five-level inverter provided in another embodiment of this application;

[0079] Figure 6 This is a schematic diagram of the structure of a five-level inverter provided in another embodiment of this application;

[0080] Figure 7 This is a schematic diagram of the structure of a five-level inverter provided in another embodiment of this application;

[0081] Figure 8 This is a schematic diagram of the structure of a five-level inverter provided in another embodiment of this application;

[0082] Figure 9 This is a schematic diagram of the structure of a switching unit provided in an embodiment of this application;

[0083] Figure 10 This is a schematic diagram of the structure of a switching unit provided in another embodiment of this application;

[0084] Figure 11 This is a schematic diagram of the structure of a semiconductor power switching unit provided in an embodiment of this application;

[0085] Figure 12 This is a schematic diagram of the structure of a semiconductor power switching unit provided in another embodiment of this application;

[0086] Figure 13 This is a schematic diagram of the structure of a semiconductor power switching unit provided in another embodiment of this application;

[0087] Figure 14 This is a schematic diagram of the structure of a semiconductor power switching unit provided in another embodiment of this application;

[0088] Figure 15 This is a schematic diagram of the clamping circuit provided in one embodiment of this application;

[0089] Figure 16 This is a schematic diagram of the structure of a fractal connector module provided in one embodiment of this application;

[0090] Figure 17 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0091] Figure 18This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0092] Figure 19 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0093] Figure 20 This is a schematic diagram of the structure of a series transformer provided in one embodiment of this application;

[0094] Figure 21 This is a schematic diagram of the structure of a series transformer provided in another embodiment of this application;

[0095] Figure 22 This is a schematic diagram of the structure of a five-level fractal converter provided in another embodiment of this application;

[0096] Figure 23 This is a schematic diagram of the structure of a harmonic generation inverter provided in one embodiment of this application. Detailed Implementation

[0097] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0098] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0099] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0100] It should be noted that the transistors in the embodiments of this application can be either N-type or P-type transistors. For N-type transistors, the on-state level is high and the off-state level is low. That is, when the gate of an N-type transistor is high, its first and second terminals are connected; when the gate of an N-type transistor is low, its first and second terminals are off. For P-type transistors, the on-state level is low and the off-state level is high. That is, when the control terminal of a P-type transistor is low, its first and second terminals are connected; when the control terminal of a P-type transistor is high, its first and second terminals are off. In specific implementations, the gate of each transistor is used as its control terminal. Furthermore, depending on the signal and type of the gate of each transistor, its first terminal can be used as the source and its second terminal as the drain, or vice versa. No distinction is made here. Additionally, the on-state and off-state levels in the embodiments of this invention are general terms. The on-state level refers to any level that enables the transistor to conduct, and the off-state level refers to any level that enables the transistor to turn off / become off.

[0101] In the embodiments of this application, the term "electrical connection" can refer to a direct electrical connection between two components, or it can refer to an electrical connection between two components via one or more other components.

[0102] In the embodiments of this application, the first node, the second node, and the third node are defined only for the convenience of describing the circuit structure, and the first node, the second node, and the third node are not actual circuit units.

[0103] Various modifications and variations can be made to this application without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, this application is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the embodiments provided in this application can be combined with each other without contradiction.

[0104] Before describing the technical solutions provided in the embodiments of this application, in order to facilitate understanding of the embodiments of this application, this application first specifically explains the problems existing in the related technologies:

[0105] As mentioned earlier, in existing AC / DC converter technologies, five-level converters have a high switching frequency, typically greater than 500Hz, resulting in high losses and heat generation in the switching devices, leading to low overall output capacity and high cost per unit capacity of the converter.

[0106] The inventors of this application have discovered that, in traditional technical solutions, increasing the output capacity of the converter requires multiple five-level converters connected in parallel, leading to a significant increase in overall cost. Alternatively, if traditional technical solutions increase output capacity by reducing the converter switching frequency and decreasing switching device losses, the five-level inverter will generate significant high-order harmonic components. Larger inductor-capacitor filters are needed to passively filter out these high-order harmonic components. Since the harmonic components generated at lower switching frequencies are large, larger passive filters are required, resulting in a rapid increase in cost and also affecting the converter's output performance.

[0107] As a result, current five-level inverters have a high switching frequency, leading to high losses in switching devices, high heat generation, low overall output capacity, and high cost per unit capacity. Therefore, how to effectively reduce the switching frequency of five-level inverters and improve the overall output capacity of the inverter has become a technical problem that urgently needs to be solved by those skilled in the art.

[0108] In view of the above, in order to solve the problems of the prior art, embodiments of this application provide a five-level fractal converter. It should be noted that the embodiments provided in this application are not intended to limit the scope of this application.

[0109] The five-level fractal converter provided in the embodiments of this application will be introduced first below. Figure 1 This is a schematic diagram of the structure of a five-level fractal converter provided in an embodiment of this application. For example... Figure 1 As shown, this application embodiment provides a five-level fractal converter 100, which includes:

[0110] The inverter module 10 includes a five-level inverter 11. The DC side of the five-level inverter 11 is electrically connected to the first DC power supply port. The five-level inverter 11 is used to output an AC signal, which includes a first harmonic signal in the higher harmonic range.

[0111] The harmonic generation module 20 includes at least one harmonic generation inverter 21. The DC side of any harmonic generation inverter 21 is electrically connected to the corresponding second DC power supply port. The corresponding harmonic generation inverter 21 is used to output a corresponding second harmonic signal according to the first harmonic signal.

[0112] The fractal connector module 30 has a first input terminal electrically connected to the AC side of the five-level inverter 11, at least one second input terminal of the fractal connector module 30 electrically connected to the AC side of at least one harmonic generating inverter 21, and an output terminal of the fractal connector module 30 electrically connected to the AC output port.

[0113] The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module 30.

[0114] Specifically, for example, the five-level inverter 11 includes multiple switching units. By reducing the switching frequency of each switching unit, the device losses of the switching units of the five-level inverter 11 can be reduced, thereby enabling the five-level inverter 11 to output greater power.

[0115] In this embodiment, the switching devices in the five-level inverter 11 operate at a relatively low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz, or 250Hz, to generate a 50Hz fundamental voltage and fundamental current. After the switching frequency of the switching unit decreases, the five-level inverter 11 outputs an AC signal, which includes the fundamental signal and the first harmonic signal within the higher harmonic range.

[0116] By reducing the switching frequency of the switching devices in the five-level inverter 11, device losses are reduced, thereby enabling the output of greater power. Compared with traditional technical solutions, the capacity can be increased by several times, which significantly reduces the cost per unit capacity of the five-level inverter 11 and improves economic efficiency.

[0117] The harmonic generation module 20 described above may include one or more harmonic generation inverters 21. For example, the harmonic generation inverter 21 may be a two-level inverter topology, a three-level inverter topology, a five-level inverter topology, a multi-level inverter topology (number of levels > 5, seven levels, nine levels, etc.), a modular multi-level inverter topology, or a cascaded H-bridge inverter topology, etc., or it may be a series-parallel connection of various inverters or a series-parallel connection of switching devices.

[0118] In this embodiment, the harmonic generation inverter 21 can be used only to generate the second harmonic signal within the corresponding higher harmonic range, and is not used to generate the fundamental signal. Therefore, the capacity of the harmonic generation inverter 21 is very small, typically less than one-tenth of the capacity of the five-level inverter 11, resulting in lower manufacturing costs. Compared to conventional technologies that use multiple five-level inverters 11 and passive filters, this application uses the harmonic generation inverter 21 to increase the overall capacity of the converter, achieving lower costs.

[0119] In one example, all switching devices in the harmonic generation inverter 21 operate at a high switching frequency, typically greater than 1500Hz. The harmonic generation inverter 21 monitors the first harmonic signal component generated by the five-level inverter 11 in real time and provides it as a control command value to the controller of the harmonic generation inverter 21, thereby controlling the output waveform of the harmonic generation inverter 21 to be the corresponding second harmonic signal that is opposite to that of the five-level inverter 11.

[0120] The first input terminal of the fractal connector module 30 is electrically connected to the AC side of the five-level inverter 11, and at least one second input terminal of the fractal connector module 30 is correspondingly electrically connected to the AC side of at least one harmonic generating inverter 21. The output terminal of the fractal connector module 30 is electrically connected to the AC output port. The second harmonic signal can compensate for the first harmonic signal within the fractal connector module 30.

[0121] In this way, the harmonic voltage and harmonic current generated by the five-level inverter 11 and the harmonic generating inverter 21 are canceled out by the fractal connector module 30, so that the voltage and current output to the AC output port of the fractal connector module 30 are mainly fundamental voltage and fundamental current components. The fractal connector module 30 achieves the effect of canceling out harmonic voltage and harmonic current components.

[0122] In this embodiment, both the first and second DC power supply ports include positive and negative connection terminals. The first and second DC power supply ports are DC power supply ports that can be connected to equipment with DC power supply ports, such as rectifiers, energy storage devices, and MPPT (Maximum Power Point Tracking) devices, and are responsible for transmitting DC power. The AC output port includes three connection terminals: phase A, phase B, and phase C.

[0123] In a five-level fractal converter 100 according to an embodiment of this application, the inverter module 10 and the harmonic generation module 20 respectively construct the power frequency fundamental wave and high-frequency harmonics, and construct a sinusoidal voltage waveform through fractal coupling on the AC side. The main function of the inverter module 10 is to output the fundamental voltage / current and adjust its amplitude and phase angle to achieve AC / DC power conversion. The main function of the harmonic generation module 20 is to output harmonic voltage or harmonic current opposite to that of the inverter module 10 to compensate for the harmonic components generated by the inverter module 10. The output waveforms of the inverter module 10 and the harmonic generation module 20 are coupled together through the fractal connector module 30 to achieve harmonic cancellation and construct a standard sinusoidal waveform.

[0124] As described above, the harmonic generation inverter 21 in the harmonic generation module 20 generates a second harmonic signal based on the first harmonic signal generated by the five-level inverter 11 in the inverter module 10, and outputs the second harmonic signal to the fractal connector module 30. This allows the first harmonic signal to be compensated by the second harmonic signal within the fractal connector module 30, thereby reducing or even eliminating the harmonics of the output electrical signal from the converter to the AC output port.

[0125] Thus, in a five-level fractal converter 100 according to an embodiment of this application, there is no need to increase the output capacity or filter out harmonics by additionally setting up multiple sets of costly five-level inverters 11 or passive filters. Through the harmonic compensation effect based on the harmonic generation module 20 and the fractal connector module 30, the switching devices of the five-level inverter 11 in the inverter module 10 can directly operate at a lower switching frequency, resulting in low switching device losses. By operating the five-level inverter 11 at a low switching frequency, the output capacity of the converter can be increased, thereby significantly reducing the cost per unit capacity of the inverter, while effectively ensuring the reliability and performance of the output signal.

[0126] Please continue reading Figure 1 Optionally, according to some embodiments of this application, the number of harmonic generation inverters 21 in the harmonic generation module 20 is 1;

[0127] The alternating current signal includes n first harmonic signals corresponding to n higher harmonic intervals, where n is greater than or equal to 1 and n is a positive integer.

[0128] The harmonic generation inverter 21 is used to output n second harmonic signals, and the n second harmonic signals correspond one-to-one with the n first harmonic signals.

[0129] As an example, see further. Figure 1 The harmonic generation module 20 includes a harmonic generation inverter 21, which generates a corresponding second harmonic signal based on the first harmonic signal generated by the five-level inverter 11. The fundamental signal generated by the five-level inverter 11 and the first harmonic signal are output to the fractal connector module 30, and the corresponding second harmonic signal generated by the harmonic generation module 20 is also output to the fractal connector module 30.

[0130] Taking n=1 as an example, if the first harmonic signal is, for example, the 3rd harmonic signal, then the corresponding second harmonic signal generated by the harmonic generation inverter 21 is also the 3rd harmonic signal. Taking n=3 as an example, if the AC signal generated by the five-level inverter 11 includes three first harmonic signals: the 3rd harmonic signal, the 5th harmonic signal, and the 7th harmonic signal, then the number of corresponding second harmonic signals generated by the harmonic generation inverter 21 is also 3, including the 3rd harmonic signal, the 5th harmonic signal, and the 7th harmonic signal.

[0131] Thus, the second harmonic signal can compensate for the corresponding first harmonic signal within the fractal connector module 30. Because the harmonic signal is compensated, the losses caused by the harmonic signals in the five-level inverter 11 are also reduced, thereby increasing the output power and capacity of the five-level fractal converter 100. Therefore, this embodiment achieves both a reduction in the switching frequency of the five-level fractal converter 100 and an increase in the converter's output capacity.

[0132] Figure 2 This is a schematic diagram of the structure of a five-level fractal converter 100 provided in another embodiment of this application. Figure 2 As shown, optionally, according to some embodiments of this application, the number of harmonic generation inverters 21 in the harmonic generation module 20 is n, where n is greater than 1 and n is a positive integer;

[0133] The AC sides of the n harmonic generation inverters 21 are electrically connected to the n second input terminals of the fractal connector module 30, respectively.

[0134] The switching frequency of the switching device of the i-th harmonic generator inverter 21 is greater than the switching frequency of the switching device of the (i-1)-th harmonic generator inverter 21, 1 < i ≤ n, where i is a positive integer;

[0135] The alternating current signal includes n first harmonic signals corresponding to n higher harmonic intervals. The n harmonic generator inverter 21 is used to output n second harmonic signals, and the n second harmonic signals correspond one-to-one with the n first harmonic signals.

[0136] The first harmonic generating inverter 21 to the nth harmonic generating inverter 21 can be a two-level inverter topology, a three-level inverter topology, a five-level inverter topology, a multi-level inverter topology (number of levels > 5, seven-level, nine-level, etc.), a modular multi-level inverter topology, or a cascaded H-bridge inverter topology, etc., without strict limitations. The switching frequency of the switching devices in the first harmonic generating inverter 21 to the nth harmonic generating inverter 21 increases with the inverter number, and the switching frequency is higher than that of the harmonic generating inverter 21 with a smaller number. It is used to assist the harmonic generating inverter 21 with a smaller number and to compensate for the higher-order harmonic voltages and harmonic currents generated by the five-level inverter 11 that are difficult for the harmonic generating inverter 21 with a smaller number to compensate.

[0137] For example, let's take an n=3 value as an example. See [link / reference] Figure 2 The harmonic generation module 20 includes three harmonic generation inverters 21, which are respectively connected to the three second input terminals of the fractal connector module 30. The switching frequency of the switching device of the third harmonic generation inverter 21 is higher than that of the second harmonic generation inverter 21, which in turn is higher than that of the first harmonic generation inverter 21. Therefore, the third harmonic generation inverter 21 is used to compensate for the highest-order harmonic signal, the first harmonic generation inverter 21 is used to compensate for the lowest-order harmonic signal, and the second harmonic generation inverter 21 is used to compensate for the intermediate-order harmonic signals.

[0138] Taking n=3 as an example, the AC signal generated by the five-level inverter 11 includes three first harmonic signals: the 3rd harmonic signal, the 5th harmonic signal, and the 7th harmonic signal. The third harmonic generating inverter 21 is used to generate the corresponding second harmonic signal of the 7th harmonic interval based on the first harmonic signal of the 7th harmonic interval. The second harmonic generating inverter 21 is used to generate the corresponding second harmonic signal of the 5th harmonic interval based on the first harmonic signal of the 5th harmonic interval. The first harmonic generating inverter 21 is used to generate the corresponding second harmonic signal of the 3rd harmonic interval based on the first harmonic signal of the 3rd harmonic interval.

[0139] It should be added that, in comparison Figure 1 and Figure 2 In both examples, where the first harmonic signal generated by the five-level inverter 11 is the same, Figure 2 The second harmonic signal generated by the inverter 21 with multiple harmonic generation and Figure 1When only one harmonic generator inverter 21 is used, the total amount of the second harmonic signal generated is the same. Therefore, when multiple harmonic generator inverters 21 are used, the total capacity of n harmonic generator inverters 21 is the same as that of using only one harmonic generator inverter 21. However, since the capacity of a single harmonic generator inverter 21 is reduced, the manufacturing cost of a single harmonic generator inverter 21 is significantly reduced. Therefore, using multiple harmonic generator inverters 21 results in lower cost.

[0140] Optionally, according to some embodiments of this application, the switching frequency of any harmonic generating inverter 21 is greater than the switching frequency of the five-level inverter 11.

[0141] In this embodiment, the switching frequency of any harmonic generating inverter 21 is greater than the switching frequency of the five-level inverter 11. All switching devices in the five-level inverter 11 operate at a lower switching frequency, typically less than 300Hz, thereby generating a fundamental voltage and current of 50Hz. All switching devices in the harmonic generating inverter 21 operate at a higher switching frequency, typically greater than 1500Hz.

[0142] Thus, by reducing the switching frequency of the switching devices in the five-level inverter 11, device losses are reduced, thereby enabling the output of greater power. The harmonic generation inverter 21 is only used to generate the second harmonic signal within the corresponding higher harmonic range and is not used to generate the fundamental signal. Therefore, the capacity of the harmonic generation inverter 21 is very small, resulting in a lower manufacturing cost. This significantly reduces the cost per unit capacity of the converter and improves economic efficiency.

[0143] Optionally, according to some embodiments of this application, such as Figures 3 to 8 As shown, the AC side of the five-level inverter 11 includes three single-phase AC output terminals (e.g., phase A, phase B, and phase C). The five-level inverter 11 includes at least one supporting capacitor and a three-phase inverter bridge, which includes three single-phase inverter bridges corresponding one-to-one with the three single-phase AC output terminals.

[0144] The single-phase inverter bridge includes bridge arm branches located between the first DC power supply ports;

[0145] The bridge arm branch includes the bridge arm midpoint, which is electrically connected to the corresponding single-phase AC output terminal.

[0146] At least one supporting capacitor is connected in series between the first DC power supply ports.

[0147] like Figures 3 to 8As shown, the following section mainly uses the single-phase inverter bridge corresponding to phase A, a single-phase AC output terminal, as an example to introduce the relevant topology. The bridge arm branch of this single-phase inverter bridge corresponding to phase A includes the bridge arm midpoint A, which is electrically connected to the corresponding single-phase AC output terminal.

[0148] The following is as follows Figure 3 As shown, optionally, according to some embodiments of this application, more specifically, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports, and the common points between adjacent switching units in the eight switching units are, in order: first node N1, second node N2, third node N3, bridge arm midpoint A, fourth node N4, fifth node N5 and sixth node N6.

[0149] At least one supporting capacitor includes: a first supporting capacitor Cbus1, a second supporting capacitor Cbus2, a third supporting capacitor Cbus3 and a fourth supporting capacitor Cbus4 sequentially disposed between the first DC power supply ports, the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 being electrically connected to the seventh node N7, the second supporting capacitor Cbus2 and the third supporting capacitor Cbus3 being electrically connected to the eighth node N8, and the third supporting capacitor Cbus3 and the fourth supporting capacitor Cbus4 being electrically connected to the ninth node N9;

[0150] At least one first diode is provided between the first node N1 and the seventh node N7, at least one second diode is provided between the seventh node N7 and the fourth node N4, at least one third diode is provided between the second node N2 and the eighth node N8, at least one fourth diode is provided between the eighth node N8 and the fifth node N5, at least one fifth diode is provided between the third node N3 and the ninth node N9, and at least one sixth diode is provided between the ninth node N9 and the sixth node N6.

[0151] In practical implementation, the first supporting capacitor Cbus1, the second supporting capacitor Cbus2, the third supporting capacitor Cbus3, and the fourth supporting capacitor Cbus4 can each be composed of a single capacitor, or they can each be composed of multiple capacitors connected in series and parallel. The first supporting capacitor Cbus1, the second supporting capacitor Cbus2, the third supporting capacitor Cbus3, and the fourth supporting capacitor Cbus4 are used to stabilize the DC bus voltage provided by the corresponding first DC power supply port, preventing sudden changes in the DC bus voltage. The capacitance values ​​of each of the above supporting capacitors can also be flexibly set according to actual voltage stabilization requirements; this embodiment does not impose strict limitations on this.

[0152] And, combined Figure 3As shown in the switching unit 110, the switching unit in this embodiment is illustrated by a switching device and a freewheeling diode connected in reverse parallel with it. The switching device in the eight switching units between the first DC power supply ports is, for example... Figure 3 The S1 to S8 components, and freewheeling diodes such as D1 to D8, are included, but this does not mean that the switching unit contains only these components.

[0153] The aforementioned switching devices can be selected from integrated gate-commutated thyristors (IGCT), insulated gate bipolar transistors (IGBT), injection-enhanced gate transistors (IEGT), or metal-oxide-semiconductor field-effect transistors (MOSFET), etc.

[0154] And, in Figure 3 In this configuration, at least one first diode, such as D9, is disposed between the first node N1 and the seventh node N7; at least one second diode, such as D10, D11, and D12, is disposed between the seventh node N7 and the fourth node N4; at least one third diode, such as D13 and D14, is disposed between the second node N2 and the eighth node N8; at least one fourth diode, such as D15 and D16, is disposed between the eighth node N8 and the fifth node N5; at least one fifth diode, such as D17, D18, and D19, is disposed between the third node N3 and the ninth node N9; and at least one sixth diode, such as D20, is disposed between the ninth node N9 and the sixth node N6.

[0155] It should be added that, in this embodiment, the number of diodes set between nodes (e.g., between the first node N1 and the seventh node N7) is not strictly limited, and can be determined according to the actual inverter requirements.

[0156] The switching devices included in the switching unit of the aforementioned five-level inverter 11 operate at a low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz or 250Hz. Their main purpose is to generate a 50Hz fundamental voltage and fundamental current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0157] In practical operation, the control terminals of the aforementioned multiple switching units are all electrically connected to their corresponding controllers. The pulse width modulation signals output by the controllers control the on and off states of each switching unit, thereby enabling the five-level inverter 11 to output the corresponding AC signal. It should be understood that, considering the diversity of existing inverter bridge driving methods, the specific driving of the aforementioned switching units and the inverter principle will not be elaborated upon in this embodiment.

[0158] The following is as follows Figure 4 As shown, optionally, according to some embodiments of this application, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units in the eight switching units are, in order: first node N1, second node N2, third node N3, bridge arm midpoint A, fourth node N4, fifth node N5 and sixth node N6.

[0159] At least one supporting capacitor includes: a first supporting capacitor Cbus1, a second supporting capacitor Cbus2, a third supporting capacitor Cbus3 and a fourth supporting capacitor Cbus4 sequentially disposed between the first DC power supply ports, the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 being electrically connected to the seventh node N7, the second supporting capacitor Cbus2 and the third supporting capacitor Cbus3 being electrically connected to the eighth node N8, and the third supporting capacitor Cbus3 and the fourth supporting capacitor Cbus4 being electrically connected to the ninth node N9;

[0160] A first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode are connected in series between the first node N1 and the sixth node N6; a seventh diode, an eighth diode, a ninth diode, and a tenth diode are connected in series between the second node N2 and the fifth node N5; and an eleventh diode and a twelfth diode are connected in series between the third node N3 and the fourth node N4.

[0161] The anode of the first diode is electrically connected to the seventh node N7, the anode of the second diode is electrically connected to the anode of the seventh diode, the anode of the third diode is electrically connected to the eighth node N8, the anode of the fourth diode is electrically connected to the anode of the ninth diode, the anode of the fifth diode is electrically connected to the ninth node N9, and the anode of the eighth diode is electrically connected to the anode of the eleventh diode.

[0162] In practical implementation, the first supporting capacitor Cbus1, the second supporting capacitor Cbus2, the third supporting capacitor Cbus3, and the fourth supporting capacitor Cbus4 can each be composed of a single capacitor, or they can each be composed of multiple capacitors connected in series and parallel. The first supporting capacitor Cbus1, the second supporting capacitor Cbus2, the third supporting capacitor Cbus3, and the fourth supporting capacitor Cbus4 are used to stabilize the DC bus voltage provided by the corresponding first DC power supply port, preventing sudden changes in the DC bus voltage. The capacitance values ​​of each of the above supporting capacitors can also be flexibly set according to actual voltage stabilization requirements; this embodiment does not impose strict limitations on this.

[0163] And, combined Figure 4 As shown in the switching unit 110, the switching unit in this embodiment is illustrated by a switching device and a freewheeling diode connected in reverse parallel with it. The switching device in the eight switching units between the first DC power supply ports is, for example... Figure 4 The S1 to S8 components, and freewheeling diodes such as D1 to D8, are included, but this does not mean that the switching unit contains only these components.

[0164] And, in Figure 4 In the configuration, the diodes positioned between the first node N1 and the sixth node N6 are, for example, D15, D16, D17, D18, D19, and D20. Between the second node N2 and the fifth node N5, the diodes are, for example, D11, D12, D13, and D14. Between the third node N3 and the fourth node N4, the diodes are, for example, D9 and D10.

[0165] It should be added that, in this embodiment, the number of diodes set between nodes (e.g., between the first node N1 and the seventh node N7) is not strictly limited, and can be determined according to the actual inverter requirements.

[0166] The switching devices included in the switching unit of the aforementioned five-level inverter 11 operate at a low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz or 250Hz. Their main purpose is to generate a 50Hz fundamental voltage and fundamental current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0167] In practical operation, the control terminals of the aforementioned multiple switching units are all electrically connected to their corresponding controllers. The pulse width modulation signals output by the controllers control the on and off states of each switching unit, thereby enabling the five-level inverter 11 to output the corresponding AC signal. It should be understood that, considering the diversity of existing inverter bridge driving methods, the specific driving of the aforementioned switching units and the inverter principle will not be elaborated upon in this embodiment.

[0168] The following is as follows Figure 5 As shown, optionally, according to some embodiments of this application, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units in the eight switching units are, in order: first node N1, second node N2, third node N3, bridge arm midpoint A, fourth node N4, fifth node N5 and sixth node N6.

[0169] At least one supporting capacitor includes: a first supporting capacitor Cbus1 and a second supporting capacitor Cbus2 sequentially disposed between the first DC power supply ports, the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 being electrically connected to the seventh node N7.

[0170] At least one switching unit is provided between the second node N2 and the seventh node N7, and at least one switching unit is provided between the seventh node N7 and the fifth node N5;

[0171] At least one capacitor is provided between the third node N3 and the fourth node N4.

[0172] In practical implementation, the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 can each be composed of a single capacitor, or they can each be composed of multiple capacitors connected in series and parallel. The first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 are used to stabilize the DC bus voltage provided by the corresponding first DC power supply port and prevent sudden changes in the DC bus voltage. The capacitance values ​​of each supporting capacitor can also be flexibly set according to the actual voltage stabilization requirements, and this embodiment does not impose strict limitations on them.

[0173] And, combined Figure 5 As shown in the switching unit 110, the switching unit in this embodiment is illustrated by a switching device and a freewheeling diode connected in reverse parallel with it. The switching device in the eight switching units between the first DC power supply ports is, for example... Figure 5 The S1 to S8 components, and freewheeling diodes such as D1 to D8, are included, but this does not mean that the switching unit contains only these components.

[0174] And, in Figure 5In the above, at least one switching unit is provided between the second node N2 and the seventh node N7, for example, a switching unit including switching device S9 and diode D9, and a switching unit including switching device S10 and diode D10. At least one switching unit is provided between the seventh node N7 and the fifth node N5, for example, a switching unit including switching device S11 and diode D11, and a switching unit including switching device S12 and diode D12. At least one capacitor is provided between the third node N3 and the fourth node N4, for example... Figure 5 The capacitor C1 in the middle.

[0175] It should be added that, in this embodiment, the number of the aforementioned switching units and / or capacitors set between nodes (e.g., between the first node N1 and the seventh node N7) is not strictly limited, and can be determined according to the actual inverter requirements.

[0176] The switching devices included in the switching unit of the aforementioned five-level inverter 11 operate at a low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz or 250Hz. Their main purpose is to generate a 50Hz fundamental voltage and fundamental current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0177] In practical operation, the control terminals of the aforementioned multiple switching units are all electrically connected to their corresponding controllers. The pulse width modulation signals output by the controllers control the on and off states of each switching unit, thereby enabling the five-level inverter 11 to output the corresponding AC signal. It should be understood that, considering the diversity of existing inverter bridge driving methods, the specific driving of the aforementioned switching units and the inverter principle will not be elaborated upon in this embodiment.

[0178] The following is as follows Figure 6 As shown, optionally, according to some embodiments of this application, the single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units in the eight switching units are, in order: first node N1, second node N2, third node N3, bridge arm midpoint A, fourth node N4, fifth node N5 and sixth node N6.

[0179] At least one first capacitor is provided between the first node N1 and the sixth node N6, at least one second capacitor is provided between the second node N2 and the fifth node N5, and at least one third capacitor is provided between the third node N3 and the fourth node N4.

[0180] In specific implementation, Figure 6In this embodiment, at least one supporting capacitor includes the aforementioned first supporting capacitor Cbus1, second supporting capacitor Cbus2, third supporting capacitor Cbus3, and fourth supporting capacitor Cbus4. Each supporting capacitor can be composed of a single capacitor, or multiple capacitors can be connected in series and parallel. The first supporting capacitor Cbus1, second supporting capacitor Cbus2, third supporting capacitor Cbus3, and fourth supporting capacitor Cbus4 are used to stabilize the DC bus voltage provided by the corresponding first DC power supply port, preventing sudden changes in the DC bus voltage. The specific capacitance values ​​of the above-mentioned supporting capacitors can also be flexibly set according to the actual voltage stabilization requirements; this embodiment does not impose strict limitations on this.

[0181] And, combined Figure 6 As shown in the switching unit 110, the switching unit in this embodiment is illustrated by a switching device and a freewheeling diode connected in reverse parallel with it. The switching device in the eight switching units between the first DC power supply ports is, for example... Figure 6 The S1 to S8 components, and freewheeling diodes such as D1 to D8, are included, but this does not mean that the switching unit contains only these components.

[0182] And, in Figure 6 In the above, at least one first capacitor, such as capacitor C4, capacitor C5 and capacitor C6, is provided between the first node N1 and the sixth node N6; at least one second capacitor, such as capacitor C2 and capacitor C3, is provided between the second node N2 and the fifth node N5; and at least one third capacitor, such as capacitor C1, is provided between the third node N3 and the fourth node N4.

[0183] It should be added that, in this embodiment, the number of the above-mentioned capacitors set between nodes (e.g., between the first node N1 and the seventh node N7) is not strictly limited, and can be determined according to actual needs.

[0184] The switching devices included in the switching unit of the aforementioned five-level inverter 11 operate at a low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz or 250Hz. Their main purpose is to generate a 50Hz fundamental voltage and fundamental current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0185] In practical operation, the control terminals of the aforementioned multiple switching units are all electrically connected to their corresponding controllers. The pulse width modulation signals output by the controllers control the on and off states of each switching unit, thereby enabling the five-level inverter 11 to output the corresponding AC signal. It should be understood that, considering the diversity of existing inverter bridge driving methods, the specific driving of the aforementioned switching units and the inverter principle will not be elaborated upon in this embodiment.

[0186] The following is as follows Figure 7 As shown, optionally, according to some embodiments of this application, a single-phase inverter bridge includes a first switch unit, a second switch unit, a third switch unit and a fourth switch unit connected in series between the first DC power supply ports. The first switch unit and the second switch unit are electrically connected to the first node N1, the second switch unit and the third switch unit are electrically connected to the midpoint A of the bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node N2.

[0187] At least one supporting capacitor includes: a first supporting capacitor Cbus1, a second supporting capacitor Cbus2, a third supporting capacitor Cbus3 and a fourth supporting capacitor Cbus4 sequentially disposed between the first DC power supply ports, the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 being electrically connected to the third node N3, the second supporting capacitor Cbus2 and the third supporting capacitor Cbus3 being electrically connected to the fourth node N4, and the third supporting capacitor Cbus3 and the fourth supporting capacitor Cbus4 being electrically connected to the fifth node N5;

[0188] The single-phase inverter bridge also includes a fifth switching unit, a sixth switching unit, a seventh switching unit, and an eighth switching unit;

[0189] The first end of the fifth switch unit is electrically connected to the first node N1, the second end of the fifth switch unit is electrically connected to the third node N3, the first end of the sixth switch unit is electrically connected to the first end of the seventh switch unit, the second end of the sixth switch unit is electrically connected to the fourth node N4, the second end of the seventh switch unit is electrically connected to the midpoint A of the bridge arm, the first end of the eighth switch unit is electrically connected to the fifth node N5, and the second end of the eighth switch unit is electrically connected to the second node N2.

[0190] In practical implementation, the first supporting capacitor Cbus1, the second supporting capacitor Cbus2, the third supporting capacitor Cbus3, and the fourth supporting capacitor Cbus4 can each be composed of a single capacitor, or they can each be composed of multiple capacitors connected in series and parallel. The first supporting capacitor Cbus1, the second supporting capacitor Cbus2, the third supporting capacitor Cbus3, and the fourth supporting capacitor Cbus4 are used to stabilize the DC bus voltage provided by the corresponding first DC power supply port, preventing sudden changes in the DC bus voltage. The capacitance values ​​of each of the above supporting capacitors can also be flexibly set according to actual voltage stabilization requirements; this embodiment does not impose strict limitations on this.

[0191] And, combined Figure 7As shown in the switching unit 110, the switching unit in this embodiment uses a switching device and a freewheeling diode connected in reverse parallel to it for illustration, but this does not mean that the switching unit only contains these devices. In this example, the first switching unit includes the switching device S1 and the diode D1, the second switching unit includes the switching device S2 and the diode D2, the third switching unit includes the switching device S3 and the diode D3, the fourth switching unit includes the switching device S4 and the diode D4, the fifth switching unit includes the switching device S5 and the diode D5, the sixth switching unit includes the switching device S6 and the diode D6, the seventh switching unit includes the switching device S7 and the diode D7, and the eighth switching unit includes the switching device S8 and the diode D8.

[0192] The switching devices included in the switching unit of the aforementioned five-level inverter 11 operate at a low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz or 250Hz. Their main purpose is to generate a 50Hz fundamental voltage and fundamental current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0193] In practical operation, the control terminals of the aforementioned multiple switching units are all electrically connected to their corresponding controllers. The pulse width modulation signals output by the controllers control the on and off states of each switching unit, thereby enabling the five-level inverter 11 to output the corresponding AC signal. It should be understood that, considering the diversity of existing inverter bridge driving methods, the specific driving of the aforementioned switching units and the inverter principle will not be elaborated upon in this embodiment.

[0194] The following is as follows Figure 8 As shown, optionally, according to some embodiments of this application, a single-phase inverter bridge includes a first switch unit, a second switch unit, a third switch unit and a fourth switch unit connected in series between the first DC power supply ports. The first switch unit and the second switch unit are electrically connected to the first node N1, the second switch unit and the third switch unit are electrically connected to the midpoint A of the bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node N2.

[0195] At least one supporting capacitor includes: a first supporting capacitor Cbus1 and a second supporting capacitor Cbus2 sequentially disposed between the first DC power supply ports, and the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 are electrically connected to the third node N3.

[0196] The single-phase inverter bridge also includes a first capacitor C1, a second capacitor C2, a fifth switching unit, a sixth switching unit, a seventh switching unit, and an eighth switching unit; the first end of the first capacitor C1 is electrically connected to the first node N1, the second end of the first capacitor C1 is electrically connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 is electrically connected to the second node N2; the first end of the fifth switching unit is electrically connected to the first end of the sixth switching unit, the first end of the fifth switching unit is electrically connected to the second end of the first capacitor C1, the second end of the sixth switching unit is electrically connected to the midpoint A of the bridge arm, the first end of the seventh switching unit is electrically connected to the first end of the eighth switching unit, the second end of the seventh switching unit is electrically connected to the second end of the first supporting capacitor Cbus1, and the second end of the eighth switching unit is electrically connected to the second end of the first capacitor C1.

[0197] In practical implementation, the first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 can each be composed of a single capacitor, or they can each be composed of multiple capacitors connected in series and parallel. The first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 are used to stabilize the DC bus voltage provided by the corresponding first DC power supply port and prevent sudden changes in the DC bus voltage. The capacitance values ​​of each supporting capacitor can also be flexibly set according to the actual voltage stabilization requirements, and this embodiment does not impose strict limitations on them.

[0198] And, combined Figure 8 As shown in the switching unit 110, the switching unit in this embodiment uses a switching device and a freewheeling diode connected in reverse parallel to it for illustration, but this does not mean that the switching unit only contains these devices. In this example, the first switching unit includes the switching device S1 and the diode D1, the second switching unit includes the switching device S2 and the diode D2, the third switching unit includes the switching device S3 and the diode D3, the fourth switching unit includes the switching device S4 and the diode D4, the fifth switching unit includes the switching device S5 and the diode D5, the sixth switching unit includes the switching device S6 and the diode D6, the seventh switching unit includes the switching device S7 and the diode D7, and the eighth switching unit includes the switching device S8 and the diode D8.

[0199] The first capacitor C1 and the second capacitor 2 mentioned above can each be composed of a single capacitor, or they can each be composed of multiple capacitors connected in series and parallel. This embodiment does not impose strict limitations on this.

[0200] The switching devices included in the switching unit of the aforementioned five-level inverter 11 operate at a low switching frequency, typically less than 300Hz, with a typical value of 50Hz, but also 100Hz, 150Hz, 200Hz or 250Hz. Their main purpose is to generate a 50Hz fundamental voltage and fundamental current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0201] In practical operation, the control terminals of the aforementioned multiple switching units are all electrically connected to their corresponding controllers. The pulse width modulation signals output by the controllers control the on and off states of each switching unit, thereby enabling the five-level inverter 11 to output the corresponding AC signal. It should be understood that, considering the diversity of existing inverter bridge driving methods, the specific driving of the aforementioned switching units and the inverter principle will not be elaborated upon in this embodiment.

[0202] Optionally, according to some embodiments of this application, in conjunction with Figures 3 to 8 As shown, the three-phase inverter bridge includes multiple switching units, and each of the multiple switching units includes multiple semiconductor power switching units 1101; the semiconductor power switching unit 1101 includes at least one of IGCT, IGBT, IEGT and MOSFET.

[0203] In any given switching unit, multiple semiconductor power switching units 1101 are connected in series.

[0204] And / or, multiple semiconductor power switch units 1101 in any one of the switch units are connected in parallel with each other.

[0205] In practical applications, combined with Figures 3 to 8 As shown, each three-phase inverter bridge includes multiple switching units, which are configured with different connection methods to form different circuit structures.

[0206] Each of the multiple switching units includes multiple semiconductor power switching units 1101. Each semiconductor power switching unit 1101 may consist of at least one switching device and a freewheeling diode connected in reverse parallel. When the switching device is turned on, the current direction from positive to negative is from the first terminal to the second terminal of the corresponding switching unit. Furthermore, each semiconductor power switching unit 1101 may also include other auxiliary devices such as resistors and capacitors according to actual needs. This application does not strictly limit the internal structure of the semiconductor power switching units.

[0207] In some embodiments, the above-mentioned switching unit may include multiple semiconductor power switching units 1101 connected in series, in parallel, or in a combination of series and parallel. The connection methods within different switching units may be the same or different, depending on the actual circuit requirements, and are not strictly limited here.

[0208] As an example, such as Figure 9As shown, taking a certain switching unit as an example, the switching unit includes multiple semiconductor power switching units 1101 connected in series. Because the multiple semiconductor power switching units 1101 are connected in series, the high voltage withstand capability of the switching unit can be enhanced. Alternatively, as another example, such as... Figure 10 As shown, taking a certain switching unit as an example, the switching unit includes multiple semiconductor power switching units 1101 connected in parallel. Since multiple semiconductor power switching units 1101 are connected in parallel, the current carrying capacity of the switching unit can be enhanced.

[0209] The following is combined with Figures 11 to 14 The following describes some specific structural examples of the semiconductor power switch unit 1101.

[0210] In some examples, such as Figure 11 As shown, the semiconductor power switching unit 1101 includes a main switch S1, an auxiliary switch S2, and a module capacitor C. MS Module resistor R MS And ports. The ports of the semiconductor power switch unit 1101 include both positive and negative terminals.

[0211] In specific connections, the module resistor R MS The first terminal is connected to the module capacitor C MS The first terminal is connected to the module resistor R. MS The second terminal is connected to the module capacitor C MS The second terminal is connected, and the first terminal of the auxiliary switch S2 is connected to the module capacitor C. MS The first terminal of the auxiliary switch S2 is connected to the first terminal of the main switch S1, and the second terminal of the main switch S1 is connected to the module capacitor C. MS The second end is connected. The first end of the main switch S1 serves as the positive terminal of the semiconductor power switch unit 1101, and the second end of the main switch S1 serves as the negative terminal of the semiconductor power switch unit 1101.

[0212] The main switch S1 can be selected from IGCT, IGBT, IEGT, or MOSFET, etc. The auxiliary switch S2 can be selected from IGBT, IEGT, MOSFET, or diode, etc. The main switch S1 can have a larger capacity than the auxiliary switch S2. For example, the main switch S1 can be selected from IGCT, and the auxiliary switch S2 can be selected from IGBT.

[0213] The above module resistor R MS It can be used to perform static voltage equalization; module capacitor C MS This can be used to achieve dynamic pressure equalization. In some possible embodiments, Figure 11 R in MSAlternatively, this setting can be omitted. Furthermore, corresponding anti-parallel diodes can be installed at both ends of the main switch S1 and the auxiliary switch S2 for freewheeling.

[0214] In other examples, such as Figure 12 As shown, the semiconductor power switching unit includes a switch S and a module capacitor C. MS Module resistor R MS The semiconductor power switch unit 1101 has two terminals: a diode (D), a Zener diode (Dz), and ports. The ports of the semiconductor power switch unit 1101 include both positive and negative terminals.

[0215] In the specific connection, the cathode of the Zener diode Dz and the module resistor R... MS The first terminal is connected to the module capacitor C respectively MS The first connection is between the anode of the Zener diode Dz and the module resistor R. MS The second terminal is connected to the module capacitor C respectively. MS The second terminal is connected, with the cathode of diode D connected to module capacitor C. MS The first terminal of diode D is connected to the first terminal of switch S, and the second terminal of switch S is connected to the module capacitor C. MS The second end is connected. The first end of switch S serves as the positive terminal of the semiconductor power switch unit 1101, and the second end of switch S serves as the negative terminal of the semiconductor power switch unit 1101.

[0216] The switch S can be selected from IGCT, IGBT, IEGT, or MOSFET, etc. The module resistor R mentioned above... MS It can be used to perform static voltage equalization; module capacitor C MS This can be used for dynamic voltage equalization; the Zener diode Dz can be used for voltage regulation; and the diode D can be used to assist in voltage equalization control. In some possible embodiments, Figure 12 R in MS Alternatively, this setting can be omitted. Also, corresponding anti-parallel diodes can be set at both ends of switch S for freewheeling.

[0217] In some other examples, such as Figure 13 As shown, the semiconductor power switching unit 1101 includes a switch S and a buffer capacitor C. S Buffer resistor R S The semiconductor power switch unit 1101 has two terminals: a positive terminal and a negative terminal.

[0218] In the specific connection, the buffer capacitor C S The first terminal is connected to the buffer resistor R S The first terminal is connected to the buffer capacitor C. S The second terminal is connected to the buffer resistor R S The second terminal is connected, and the first terminal of switch S is connected to the buffer capacitor C.S The first terminal is connected, and the second terminal of switch S is connected to the buffer capacitor C. S The second end is connected. The first end of switch S serves as the positive terminal of the semiconductor power switch unit 1101, and the second end of switch S serves as the negative terminal of the semiconductor power switch unit 1101.

[0219] The switch S can be selected from IGCT, IGBT, IEGT, or MOSFET, etc. The aforementioned buffer capacitor C... S It can be used to provide buffer protection; the buffer resistor R S This can be used for static voltage equalization and current limiting protection. Additionally, corresponding anti-parallel diodes can be installed at both ends of switch S for freewheeling.

[0220] In some other examples, such as Figure 14 As shown, the semiconductor power switching unit 1101 includes a switch S and a buffer capacitor C. S Buffer resistor R S Diode D, static voltage equalization resistor R d The semiconductor power switch unit 1101 has two terminals: a positive terminal and a negative terminal.

[0221] In the specific connection, the static voltage equalization resistor R d The first terminal is connected to the buffer resistor R S The first terminal is connected to the buffer resistor R. S The first terminal is connected to the buffer capacitor C S The first terminal is connected to the static equalizing resistor R. d The second terminal is connected to the buffer capacitor C S The second terminal is connected, with the anode of diode D connected to the buffer resistor R. S The first terminal is connected, with the cathode of diode D connected to the buffer resistor R. S The second terminal of switch S is connected to the anode of diode D, and the second terminal of switch S is connected to the buffer capacitor C. S The second end is connected. The first end of switch S serves as the positive terminal of the semiconductor power switch unit 1101, and the second end of switch S serves as the negative terminal of the semiconductor power switch unit 1101.

[0222] The switch S can be selected from IGCT, IGBT, IEGT, or MOSFET, etc. The aforementioned buffer capacitor C... S It can be used to provide buffer protection; the buffer resistor R S It can be used to provide current limiting protection; static equalizing resistor R d It can be used for static voltage equalization. Furthermore, corresponding anti-parallel diodes can be installed at both ends of switch S for freewheeling.

[0223] It should be noted that when multiple semiconductor power switch units 1101 are connected in series, the positive terminal in the port of the current semiconductor power switch unit 1101 is used to connect with the negative terminal in the port of the adjacent previous semiconductor power switch unit 1101, and the negative terminal in the port of the current semiconductor power switch unit 1101 is used to connect with the positive terminal in the port of the adjacent next semiconductor power switch unit 1101.

[0224] When multiple semiconductor power switch units 1101 are connected in parallel, the positive terminal of the current semiconductor power switch unit 1101 is used to connect with the positive terminal of the adjacent preceding semiconductor power switch unit 1101, and the negative terminal of the current semiconductor power switch unit 1101 is used to connect with the negative terminal of the adjacent following semiconductor power switch unit 1101. The direction from the positive terminal to the negative terminal of any semiconductor power switch unit 1101 is consistent with the direction from the first end to the second end of the switch unit it belongs to.

[0225] Optionally, according to some embodiments of this application, such as Figure 15 As shown, the semiconductor power switch unit 1101 in any switching unit includes an IGCT;

[0226] The five-level inverter 11 also includes a clamping circuit disposed between the first DC power supply ports. In practical applications, this clamping circuit can be disposed between the support capacitor and the three-phase inverter bridge to ensure sufficient clamping.

[0227] Combination Figure 15 As shown, the clamping circuit includes an anode reactance Lbuf, a clamping diode Dbuf, a clamping resistor Rbuf, and a clamping capacitor Cbuf.

[0228] The first terminal of the anode reactance Lbuf is connected to the positive terminal of the corresponding first DC power supply port. The second terminal of the anode reactance Lbuf is connected to the anode of the clamping diode Dbuf. The anode of the clamping diode Dbuf is connected to the first terminal of the clamping capacitor Cbuf. The second terminal of the clamping capacitor Cbuf is connected to the negative terminal of the corresponding first DC power supply port. The first terminal of the clamping resistor Rbuf is connected to the first terminal of the anode reactance Lbuf. The second terminal of the clamping resistor Rbuf is electrically connected to the cathode of the clamping diode Dbuf.

[0229] Specifically, when any of the multiple switching units includes an IGCT as the switching device, the clamping circuit is used to limit the rate of change of the current when the semiconductor power switching unit is turned on, and to limit the oscillation amplitude of the AC side output voltage of the single-phase inverter bridge, thereby effectively realizing the clamping protection of the circuit elements.

[0230] It should be noted that the clamping circuit described above is used to protect the IGCT device, and its topology is only an example topology; other topologies are also possible. In some embodiments, if the IGCT is not included in the switching unit, the clamping circuit may not be provided in the five-level inverter 11. Therefore, in the circuit topology of the five-level inverter 11, the inclusion or exclusion of the clamping circuit can be flexibly selected based on the characteristics of the three-phase inverter bridge in the actual cascaded unit, and this embodiment does not impose strict limitations on it.

[0231] Optionally, according to some embodiments of this application, such as Figure 16 As shown, the fractal connector module 30 includes: a first winding 311, at least one second winding 312, and a third winding 313;

[0232] The first winding 311, at least one second winding 312, and the third winding 313 are coupled together;

[0233] The first winding 311 is electrically connected to the AC side of the five-level inverter 11, at least one second winding 312 is electrically connected to the AC side of at least one harmonic generating inverter 21, and the third winding 313 is electrically connected to the AC output port.

[0234] For example, the first winding 311 can be a star-connected winding or a delta-connected winding, the second winding 312 can be a star-connected winding or a delta-connected winding, and the third winding 313 can be a star-connected winding or a delta-connected winding.

[0235] In practice, after the switching frequency of the switching unit in the five-level inverter 11 is reduced, the five-level inverter 11 generates the first harmonic signal in the higher harmonic range. The fundamental signal and the first harmonic signal generated by the five-level inverter 11 are output to the first winding 311, and the harmonic generation inverter 21 generates the corresponding second harmonic signal based on the first harmonic signal, which is then output to the second winding 312.

[0236] Since the waveform of the second harmonic signal is opposite to that of the first harmonic signal, the second harmonic signal compensates for the first harmonic signal, thereby reducing the harmonic signal at the AC output port and reducing the losses caused by the harmonic signal. This enhances the maximum power output capability of the five-level fractal converter 100 and increases the output capacity of the five-level fractal converter 100. The final generated fundamental signal is output to the AC output port through the third winding 313.

[0237] When the harmonic generation module 20 includes multiple harmonic generation inverters 21, the fractal connector module 30 includes the same number of second windings 312. The multiple second windings 312 are connected to the corresponding harmonic generation inverters 21 and coupled to other windings. This allows the second harmonic signals of different higher harmonic ranges generated by different harmonic generation inverters 21 to be introduced into the fractal connector module 30, thereby enabling the compensation of the first harmonic signals of different higher harmonic ranges.

[0238] Alternatively, according to some embodiments of this application, please continue to refer to... Figure 16 The first winding 311 includes a delta winding, any second winding 312 includes a star winding or a delta winding, and the third winding 313 includes a star winding or a delta winding.

[0239] Specifically, the fractal connector module 30 has a corner winding connected to the five-level inverter 11, meaning the first winding 311 includes a corner winding. This inherently eliminates the third harmonic component. Therefore, the harmonic generation inverter 21 only needs to generate the second harmonic signal in the higher harmonic ranges other than the third harmonic range. In other words, the harmonic generation inverter 21 only needs to compensate for and cancel higher harmonics above the fifth order. Thus, by connecting the corner winding in the fractal connector module 30 to the five-level inverter 11, the capacity of the harmonic generation inverter 21 can be reduced, which helps to reduce the cost of the harmonic generation inverter 21 in the five-level fractal converter 100.

[0240] Optionally, according to some embodiments of this application, such as Figure 17 As shown, the fractal connector module 30 includes at least one fourth winding 321 and at least one fifth winding 322;

[0241] The fourth winding 321 is coupled to the corresponding fifth winding 322. The fourth winding 321 is electrically connected to the AC side of the five-level inverter 11. The fifth winding 322 is electrically connected to the AC side of the corresponding harmonic generation inverter 21. The AC side of the five-level inverter 11 is electrically connected to the AC output port.

[0242] For example, the fourth winding 321 can be either a star-connected winding or a delta-connected winding, and the fifth winding 322 can be either a star-connected winding or a delta-connected winding. Figure 17 The indication in the image does not serve a limiting function.

[0243] In practical implementation, after the switching frequency of the switching unit within the five-level inverter 11 decreases, the five-level inverter 11 generates the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the five-level inverter 11 are output to the fourth winding 321, and the second harmonic signal generated by the harmonic generation inverter 21 based on the first harmonic signal is output to the fifth winding 322. When there is a voltage level mismatch between the AC output voltage of the five-level inverter 11 and the AC output voltage of the harmonic generation inverter 21, the voltage levels between the AC sides of the five-level inverter 11 and the harmonic generation inverter 21 can be matched through a parallel transformer composed of the fourth winding 321 and the fifth winding 322.

[0244] Since the waveform of the second harmonic signal is opposite to that of the first harmonic signal, the second harmonic signal compensates for the first harmonic signal, thereby reducing the harmonic signal at the AC output port and reducing the losses caused by the harmonic signal. This enhances the maximum power output capability of the five-level fractal converter 100 and increases the output capacity of the five-level fractal converter 100. The final generated fundamental signal is then output to the AC output port.

[0245] When the harmonic generation module 20 includes multiple harmonic generation inverters 21, the fractal connector module 30 includes the same number of fourth windings 321 and fifth windings 322. The multiple fourth windings 321 are electrically connected to the AC side of the five-level inverter 11, and the multiple fifth windings 322 are electrically connected to the corresponding multiple harmonic generation inverters 21. The multiple fourth windings 321 are also coupled to the corresponding fifth windings 322. This allows the second harmonic signals of different higher harmonic ranges generated by different harmonic generation inverters 21 to be introduced into the fractal connector module 30, thereby compensating for the first harmonic signals of different higher harmonic ranges.

[0246] Optionally, according to some embodiments of this application, such as Figure 18 As shown, the fractal connector module 30 includes: at least one connecting component;

[0247] The AC side of the five-level inverter 11 is electrically connected to the AC side of the corresponding harmonic generating inverter 21 through a connecting component, so that the AC side of the five-level inverter 11 is connected in parallel with the AC side of the corresponding harmonic generating inverter 21.

[0248] The AC side of the five-level inverter 11 is electrically connected to the AC output port.

[0249] In this embodiment, the connecting component is, for example, a connecting harness. When the voltage levels between the AC side of the five-level inverter 11 and the AC side of the harmonic generating inverter 21 are matched, the AC side of the five-level inverter 11 is directly connected to the AC side of the harmonic generating inverter 21 within the fractal connector module 30 to form a parallel structure, thereby saving transformer costs.

[0250] Optionally, according to some embodiments of this application, such as Figure 19 As shown, the fractal connector module 30 includes at least one series transformer 330;

[0251] The first input terminal of the series transformer 330 is electrically connected to the AC side of the five-level inverter 11, the second input terminal of the series transformer 330 is electrically connected to the AC side of the corresponding harmonic generation inverter 21, and the output terminal of the series transformer 330 is electrically connected to the AC output port.

[0252] In practice, after the switching frequency of the switching unit in the five-level inverter 11 is reduced, the five-level inverter 11 generates the first harmonic signal in the higher harmonic range. The fundamental signal and the first harmonic signal generated by the five-level inverter 11 are output to the series transformer 330, and the second harmonic signal generated by the harmonic generation inverter 21 based on the first harmonic signal is also output to the series transformer 330.

[0253] The second harmonic signal compensates for the first harmonic signal through the series transformer 330, thereby reducing the harmonic signal at the AC output port and reducing the losses caused by the harmonic signal. This enhances the maximum power output capability of the five-level fractal converter 100 and increases the output capacity of the five-level fractal converter 100. The final generated fundamental signal is output to the AC output port through the series transformer 330.

[0254] When the harmonic generation module 20 includes multiple harmonic generation inverters 21, the fractal connector module 30 includes the same number of series transformers 330. The multiple series transformers 330 are connected to the corresponding harmonic generation inverters 21 and connected to the AC side of the five-level inverter 11 connected in series. This allows the second harmonic signals of different higher harmonic ranges generated by different harmonic generation inverters 21 to be introduced into the fractal connector module 30, thereby enabling the compensation of the first harmonic signals of different higher harmonic ranges.

[0255] Optionally, according to some embodiments of this application, such as Figure 20 As shown, the series transformer 330 includes: a first transformer 331, a second transformer 332, and a third transformer 333;

[0256] The first terminal of the first transformer 331 is electrically connected to the first terminal of the AC side of the five-level inverter 11, the second terminal of the first transformer 331 is electrically connected to the first terminal of the AC output port, the third terminal of the first transformer 331 is electrically connected to the neutral point or ground terminal, and the fourth terminal of the first transformer 331 is electrically connected to the first terminal of the AC side of the harmonic generation inverter 21.

[0257] The first terminal of the second transformer 332 is electrically connected to the second terminal of the AC side of the five-level inverter 11, the second terminal of the second transformer 332 is electrically connected to the second terminal of the AC output port, the third terminal of the second transformer 332 is electrically connected to the neutral point or ground terminal, and the fourth terminal of the second transformer 332 is electrically connected to the second terminal of the AC side of the harmonic generation inverter 21.

[0258] The first terminal of the third transformer 333 is electrically connected to the third terminal of the AC side of the five-level inverter 11, the second terminal of the third transformer 333 is electrically connected to the third terminal of the AC output port, the third terminal of the third transformer 333 is electrically connected to the neutral point or ground terminal, and the fourth terminal of the third transformer 333 is electrically connected to the third terminal of the AC side of the harmonic generation inverter 21.

[0259] like Figure 20 As shown, the first transformer 331, the second transformer 332, and the third transformer 333 are single-phase, dual-winding transformers. One winding of the first transformer 331 is connected to the A-phase terminal of the AC output port and the A-phase terminal of the AC side of the five-level inverter 11, respectively. The other winding is connected to the A-phase terminal of the AC side of the harmonic generator inverter 21 and ground, respectively. This connection method enables the series connection of the AC A-phase of the five-level inverter 11 and the harmonic generator inverter 21, and connects it to the A-phase of the AC output port. The second transformer 332 and the third transformer 333 are used for the series connection of the B-phase and C-phase of the five-level inverter 11 and the harmonic generator inverter 21 on the AC side, respectively, and are connected to the B-phase and C-phase of the AC output port.

[0260] In practice, after the switching frequency of the switching unit in the five-level inverter 11 is reduced, the five-level inverter 11 generates the first harmonic signal in the higher harmonic range. The fundamental signal and the first harmonic signal generated by the five-level inverter 11 are output from different output terminals. The second harmonic signal generated by the harmonic generation inverter 21 based on the first harmonic signal is also output through different output terminals. The harmonic signals output from different output terminals of the five-level inverter 11 and the harmonic signals output from different output terminals of the harmonic generation inverter 21 are all output to the first transformer 331, the second transformer 332, and the third transformer 333.

[0261] Since the waveform of the second harmonic signal is opposite to that of the first harmonic signal, the second harmonic signal compensates for the first harmonic signal, thereby reducing the harmonic signal at the AC output port and reducing the losses caused by the harmonic signal. This enhances the maximum power output capability of the five-level fractal converter 100 and increases the output capacity of the five-level fractal converter 100.

[0262] Optionally, according to some embodiments of this application, such as Figure 21 As shown, the series transformer 330 includes: a first single-phase winding 334, a second single-phase winding 335, a third single-phase winding 336, and a sixth winding 337.

[0263] The first single-phase winding 334, the second single-phase winding 335, and the third single-phase winding 336 are electrically coupled to the sixth winding 337.

[0264] The first end of the first single-phase winding 334 is electrically connected to the first end of the AC side of the five-level inverter 11, and the second end of the first single-phase winding 334 is electrically connected to the first end of the AC output port.

[0265] The first end of the second single-phase winding 335 is electrically connected to the second end of the AC side of the five-level inverter 11, and the second end of the second single-phase winding 335 is electrically connected to the second end of the AC output port.

[0266] The first end of the third single-phase winding 336 is electrically connected to the third end of the AC side of the five-level inverter 11, and the second end of the third single-phase winding 336 is electrically connected to the third end of the AC output port.

[0267] The sixth winding 337 is electrically connected to the first terminal, the second terminal, and the third terminal of the AC side of the corresponding harmonic generating inverter 21.

[0268] like Figure 21 As shown, when the series transformer 330 adopts a three-phase multi-winding transformer, a three-phase transformer is used. One side of the three-phase transformer is connected to the harmonic generating inverter 21, and this side is a three-phase star-connected or delta-connected winding; the other side is three independent single-phase windings, and these three single-phase windings share a magnetic core.

[0269] In practice, the sixth winding 337 can be either a star-connected winding or a delta-connected winding. After the switching frequency of the switching unit in the five-level inverter 11 decreases, the five-level inverter 11 generates the first harmonic signal in the higher harmonic range. The fundamental signal and the first harmonic signal generated by the five-level inverter 11 are output from different output terminals. The second harmonic signal generated by the harmonic generation inverter 21 based on the first harmonic signal is also output through different output terminals. The harmonic signals output from different output terminals of the five-level inverter 11 are all output to the first single-phase winding 334, the second single-phase winding 335, and the third single-phase winding 336. The harmonic signals output from different output terminals of the harmonic generation inverter 21 are all output to the sixth winding 337.

[0270] Since the waveform of the second harmonic signal is opposite to that of the first harmonic signal, the second harmonic signal compensates for the first harmonic signal. As the harmonic signal is reduced, the loss caused by the harmonic signal is also reduced, thereby enhancing the maximum power output capability of the five-level fractal converter 100 and increasing the output capacity of the five-level fractal converter 100.

[0271] It should be added that, Figure 16 The multi-winding electromagnetic coupling of the fractal connector module 30 shown enables the AC output port to exhibit voltage or current source characteristics, making it suitable for various scenarios. Figure 17 or Figure 18 The parallel coupling scheme shown can help the AC output port exhibit current source characteristics. Figures 19-21 The series coupling scheme shown can help the AC output port exhibit voltage source characteristics. Therefore, the specific topology selection of the fractal connector module 30 can be flexibly set according to the actual power supply characteristics of the AC output port, and no flexible restrictions are imposed here.

[0272] Accordingly, when the AC output port needs to exhibit voltage source characteristics, the harmonic signal generated by the harmonic generation inverter 21 is a harmonic voltage; when the AC output port needs to exhibit current source characteristics, the harmonic signal generated by the harmonic generation inverter 21 is a harmonic current. In this way, by directly compensating for the harmonics of the voltage or current to be exhibited, the reliability and output performance of the AC output port signal can be fully guaranteed.

[0273] Optionally, according to some embodiments of this application, such as Figure 22 As shown, the five-level fractal converter 100 also includes:

[0274] The first filter 40 has its first end electrically connected to the AC side of the five-level inverter 11, and its second end electrically connected to the first input end of the fractal connector module 30.

[0275] And / or, the second filter 50, the first end of the second filter 50 is electrically connected to the AC side of the corresponding harmonic generating inverter 21, and the second end of the second filter 50 is electrically connected to the corresponding second input end in the fractal connector module 30.

[0276] For example, the first filter 40 and / or the second filter 50 can be passive filters composed of inductors and capacitors, and can be selected as one of L filter, LC filter, LCL filter and LCLL filter.

[0277] The first filter 40 is used to filter out interference signals in the AC output of the five-level inverter 11, thereby helping to improve the quality of the converter output signal and also helping to reduce the cost of the harmonic generation inverter 21. The first filter 40 can be flexibly configured according to actual needs.

[0278] In the case where the harmonic generating inverter 21 includes a two-level inverter, a three-level inverter, or a five-level inverter, considering that such inverters are affected by pulse width modulation characteristics and generate higher harmonics in their high-frequency switching frequency sidebands, a second filter 50 is set in this case to filter the higher harmonics of the harmonic generating inverter 21 itself, reduce the introduction of new harmonic components, and thus improve the signal performance and quality of the AC output port.

[0279] In some embodiments, the harmonic generating inverter 21 can be a two-level inverter topology, a three-level inverter topology, a five-level inverter topology, a multi-level inverter topology (number of levels > 5, seven levels, nine levels, etc.), a modular multi-level inverter topology, a cascaded H-bridge inverter topology, etc., or it can be a structure of multiple inverters connected in series and parallel or switching devices connected in series and parallel.

[0280] For example, such as Figure 23 As shown, when the harmonic generating inverter 21 uses a two-level inverter topology, the harmonic generating inverter 21 includes a first semiconductor switch 211, a second semiconductor switch 212, a third semiconductor switch 213, a fourth semiconductor switch 214, a fifth semiconductor switch 215, and a sixth semiconductor switch 216.

[0281] The first semiconductor switch 211, the second semiconductor switch 212, the third semiconductor switch 213, the fourth semiconductor switch 214, the fifth semiconductor switch 215, and the sixth semiconductor switch 216 each include at least one semiconductor power switch unit. The specific structure of the semiconductor power switch unit can be found in the preceding text. Figures 11-14 The structure example shown.

[0282] The first end of the first semiconductor switch 211 is connected to the positive terminal of the second DC power supply port, the second end of the first semiconductor switch 211 and the first end of the second semiconductor switch 212 are connected to the midpoint D of the fourth bridge arm, and the second end of the second semiconductor switch 212 is connected to the negative terminal of the second DC power supply port.

[0283] The first end of the third semiconductor switch 213 is connected to the positive terminal of the second DC power supply port, the second end of the third semiconductor switch 213 is connected to the first end of the fourth semiconductor switch 214 at the midpoint E of the fifth bridge arm, and the second end of the fourth semiconductor switch 214 is connected to the negative terminal of the second DC power supply port.

[0284] The first end of the fifth semiconductor switch 215 is connected to the positive terminal of the second DC power supply port, the second end of the fifth semiconductor switch 215 is connected to the first end of the sixth semiconductor switch 216 at the midpoint F of the sixth bridge arm, and the second end of the sixth semiconductor switch 216 is connected to the negative terminal of the second DC power supply port.

[0285] The midpoints D of the fourth bridge arm, E of the fifth bridge arm, and F of the sixth bridge arm are all connected to the fractal connector module 30.

[0286] In specific implementation, the first harmonic signal generated by the five-level fractal converter 100 is detected, and the first semiconductor switch 211, the second semiconductor switch 212, the third semiconductor switch 213, the fourth semiconductor switch 214, the fifth semiconductor switch 215, and the sixth semiconductor switch 216 are controlled to turn on and off according to the first harmonic signal, so that the second harmonic signal with the opposite waveform to the first harmonic signal is output and output to the fractal connector module 30.

[0287] Since the waveform of the second harmonic signal is opposite to that of the first harmonic signal, the second harmonic signal in the fractal connector module 30 can cancel out the part of the first harmonic signal that has the same value as the second harmonic signal. This achieves compensation of the first harmonic signal by the second harmonic signal. As the harmonic signal is reduced, the loss caused by the harmonic signal is also reduced, thereby enhancing the maximum power output capability of the five-level fractal converter 100. While reducing the switching frequency of the five-level inverter 11, the output capacity of the converter can also be increased.

[0288] It is understood that the above are all examples and do not serve as a substantial limitation on the five-level fractal converter 100 protected in this application.

[0289] It should be added that the five-level fractal converter 100 provided in this application can realize decoupled control of AC and DC voltages and bidirectional power transmission, and can be used as an inverter or a rectifier.

[0290] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0291] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0292] It should be clarified that the various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. According to the embodiments described above, these embodiments do not exhaustively describe all details, nor do they limit this application to only the specific embodiments described. Obviously, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to make good use of this application and modifications based on it. This application is limited only by the claims and their full scope and equivalents.

[0293] Those skilled in the art will understand that the above embodiments are exemplary and not restrictive. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Based on a study of the drawings, specification, and claims, those skilled in the art should be able to understand and implement other variations of the disclosed embodiments. In the claims, the term "comprising" does not exclude other structures; the quantity refers to "one" but does not exclude multiple; the terms "first" and "second" are used to identify names and not to indicate any particular order. Any reference numerals in the claims should not be construed as limiting the scope of protection. The appearance of certain technical features in different dependent claims does not mean that these technical features cannot be combined to achieve beneficial effects.

[0294] This document uses specific examples to illustrate the principles and implementation methods of this application. The examples are merely for the purpose of helping to understand the method and core ideas of this application. The above are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, and the existence of an infinite number of specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the concept and technical solution of this application to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A five-level fractal converter, characterized in that, The five-level fractal converter includes: The inverter module includes a five-level inverter, wherein the DC side of the five-level inverter is electrically connected to a first DC power supply port, and the five-level inverter is used to output an AC signal, wherein the AC signal includes a first harmonic signal in the higher harmonic range. The harmonic generation module includes at least one harmonic generation inverter, wherein the DC side of any of the harmonic generation inverters is electrically connected to a corresponding second DC power supply port, and the corresponding harmonic generation inverter is used to output a corresponding second harmonic signal according to the first harmonic signal. The fractal connector module has a first input terminal electrically connected to the AC side of the five-level inverter, at least one second input terminal of the fractal connector module electrically connected to the AC side of at least one harmonic generating inverter, and an output terminal of the fractal connector module electrically connected to an AC output port. The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module.

2. The five-level fractal converter according to claim 1, characterized in that, The number of harmonic generation inverters in the harmonic generation module is 1; The alternating current signal includes n first harmonic signals corresponding to n higher harmonic intervals, where n is greater than or equal to 1 and n is a positive integer. The harmonic generation inverter is used to output n second harmonic signals, and the n second harmonic signals correspond one-to-one with the n first harmonic signals.

3. The five-level fractal converter according to claim 1, characterized in that, The number of harmonic generation inverters in the harmonic generation module is n, where n is greater than 1 and n is a positive integer. The AC sides of the n harmonic generation inverters are electrically connected to the n second input terminals of the fractal connector module, respectively. The switching frequency of the switching device of the i-th harmonic generating inverter is greater than the switching frequency of the switching device of the (i-1)-th harmonic generating inverter, 1 < i ≤ n, where i is a positive integer; The alternating current signal includes n first harmonic signals corresponding to n higher harmonic intervals. The n harmonic generation inverter is used to output n second harmonic signals, and the n second harmonic signals correspond one-to-one with the n first harmonic signals.

4. The five-level fractal converter according to claim 1, characterized in that, The switching frequency of any of the harmonic generating inverters is greater than the switching frequency of the five-level inverter.

5. The five-level fractal converter according to claim 1, characterized in that, The AC side of the five-level inverter includes three single-phase AC output terminals; the five-level inverter includes at least one supporting capacitor and a three-phase inverter bridge, the three-phase inverter bridge including three single-phase inverter bridges that correspond one-to-one with the three single-phase AC output terminals; The single-phase inverter bridge includes bridge arm branches disposed between the first DC power supply ports; The bridge arm branch includes the bridge arm midpoint, which is electrically connected to the corresponding single-phase AC output terminal. The at least one supporting capacitor is connected in series between the first DC power supply ports.

6. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node. The at least one supporting capacitor includes: a first supporting capacitor, a second supporting capacitor, a third supporting capacitor and a fourth supporting capacitor sequentially disposed between the first DC power supply ports, wherein the first supporting capacitor and the second supporting capacitor are electrically connected to a seventh node, the second supporting capacitor and the third supporting capacitor are electrically connected to an eighth node, and the third supporting capacitor and the fourth supporting capacitor are electrically connected to a ninth node. At least one first diode is disposed between the first node and the seventh node, at least one second diode is disposed between the seventh node and the fourth node, at least one third diode is disposed between the second node and the eighth node, at least one fourth diode is disposed between the eighth node and the fifth node, at least one fifth diode is disposed between the third node and the ninth node, and at least one sixth diode is disposed between the ninth node and the sixth node.

7. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node. The at least one supporting capacitor includes: a first supporting capacitor, a second supporting capacitor, a third supporting capacitor and a fourth supporting capacitor sequentially disposed between the first DC power supply ports, wherein the first supporting capacitor and the second supporting capacitor are electrically connected to a seventh node, the second supporting capacitor and the third supporting capacitor are electrically connected to an eighth node, and the third supporting capacitor and the fourth supporting capacitor are electrically connected to a ninth node. A first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode are connected in series between the first node and the sixth node; a seventh diode, an eighth diode, a ninth diode, and a tenth diode are connected in series between the second node and the fifth node; and an eleventh diode and a twelfth diode are connected in series between the third node and the fourth node. The anode of the first diode is electrically connected to the seventh node, the anode of the second diode is electrically connected to the anode of the seventh diode, the anode of the third diode is electrically connected to the eighth node, the anode of the fourth diode is electrically connected to the anode of the ninth diode, the anode of the fifth diode is electrically connected to the ninth node, and the anode of the eighth diode is electrically connected to the anode of the eleventh diode.

8. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node. The at least one supporting capacitor includes: a first supporting capacitor and a second supporting capacitor sequentially disposed between the first DC power supply ports, wherein the first supporting capacitor and the second supporting capacitor are electrically connected to the seventh node; At least one switching unit is provided between the second node and the seventh node, and at least one switching unit is provided between the seventh node and the fifth node; At least one capacitor is provided between the third node and the fourth node.

9. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes eight switching units connected in series between the first DC power supply ports. The common points between adjacent switching units are, in order: the first node, the second node, the third node, the midpoint of the bridge arm, the fourth node, the fifth node, and the sixth node. At least one first capacitor is provided between the first node and the sixth node, at least one second capacitor is provided between the second node and the fifth node, and at least one third capacitor is provided between the third node and the fourth node.

10. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit connected in series between the first DC power supply ports. The first switch unit and the second switch unit are electrically connected to a first node, the second switch unit and the third switch unit are electrically connected to the midpoint of the bridge arm, and the third switch unit and the fourth switch unit are electrically connected to a second node. The at least one supporting capacitor includes: a first supporting capacitor, a second supporting capacitor, a third supporting capacitor, and a fourth supporting capacitor sequentially disposed between the first DC power supply ports, wherein the first supporting capacitor and the second supporting capacitor are electrically connected to a third node, the second supporting capacitor and the third supporting capacitor are electrically connected to a fourth node, and the third supporting capacitor and the fourth supporting capacitor are electrically connected to a fifth node. The single-phase inverter bridge also includes a fifth switching unit, a sixth switching unit, a seventh switching unit, and an eighth switching unit; The first end of the fifth switch unit is electrically connected to the first node, the second end of the fifth switch unit is electrically connected to the third node, the first end of the sixth switch unit is electrically connected to the first end of the seventh switch unit, the second end of the sixth switch unit is electrically connected to the fourth node, the second end of the seventh switch unit is electrically connected to the midpoint of the bridge arm, the first end of the eighth switch unit is electrically connected to the fifth node, and the second end of the eighth switch unit is electrically connected to the second node.

11. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes a first switch unit, a second switch unit, a third switch unit, and a fourth switch unit connected in series between the first DC power supply ports. The first switch unit and the second switch unit are electrically connected to a first node, the second switch unit and the third switch unit are electrically connected to the midpoint of the bridge arm, and the third switch unit and the fourth switch unit are electrically connected to a second node. The at least one supporting capacitor includes: a first supporting capacitor and a second supporting capacitor sequentially disposed between the first DC power supply ports, wherein the first supporting capacitor and the second supporting capacitor are electrically connected to a third node; The single-phase inverter bridge further includes a first capacitor, a second capacitor, a fifth switching unit, a sixth switching unit, a seventh switching unit, and an eighth switching unit; the first end of the first capacitor is electrically connected to the first node, the second end of the first capacitor is electrically connected to the first end of the second capacitor, and the second end of the second capacitor is electrically connected to the second node; the first end of the fifth switching unit is electrically connected to the first end of the sixth switching unit, the first end of the fifth switching unit is electrically connected to the second end of the first capacitor, the second end of the sixth switching unit is electrically connected to the midpoint of the bridge arm, the first end of the seventh switching unit is electrically connected to the first end of the eighth switching unit, the second end of the seventh switching unit is electrically connected to the second end of the first supporting capacitor, and the second end of the eighth switching unit is electrically connected to the second end of the first capacitor.

12. The five-level fractal converter according to claim 5, characterized in that, The single-phase inverter bridge includes multiple switching units, and each of the multiple switching units includes multiple semiconductor power switching units; the semiconductor power switching units include at least one of IGCT, IGBT, IEGT and MOSFET. In any one of the semiconductor power switch units, the plurality of semiconductor power switch units are connected in series. And / or, the plurality of semiconductor power switching units in any of the said switching units are connected in parallel with each other.

13. The five-level fractal converter according to claim 12, characterized in that, The semiconductor switching unit in any of the aforementioned switching units includes an IGCT; The five-level inverter also includes a clamping circuit disposed between the first DC power supply ports.

14. The five-level fractal converter according to any one of claims 1-13, characterized in that, The fractal connector module includes: a first winding, at least one second winding, and a third winding; The first winding, the at least one second winding, and the third winding are coupled together; The first winding is electrically connected to the AC side of the five-level inverter, the at least one second winding is electrically connected to the AC side of at least one harmonic generating inverter, and the third winding is electrically connected to the AC output port.

15. The five-level fractal converter according to claim 14, characterized in that, The first winding includes a delta winding, any second winding includes a star winding or a delta winding, and the third winding includes a star winding or a delta winding.

16. The five-level fractal converter according to any one of claims 1-13, characterized in that, The fractal connector module includes: at least one fourth winding and at least one fifth winding; The fourth winding is coupled to the corresponding fifth winding, the fourth winding is electrically connected to the AC side of the five-level inverter, the fifth winding is electrically connected to the AC side of the corresponding harmonic generating inverter, and the AC side of the five-level inverter is electrically connected to the AC output port.

17. The five-level fractal converter according to any one of claims 1-13, characterized in that, The fractal connector module includes: at least one connecting component; The AC side of the five-level inverter is electrically connected to the AC side of the corresponding harmonic generating inverter through the connecting component, so that the AC side of the five-level inverter and the AC side of the corresponding harmonic generating inverter are connected in parallel. The AC side of the five-level inverter is electrically connected to the AC output port.

18. The five-level fractal converter according to any one of claims 1-13, characterized in that, The fractal connector module includes at least one series transformer; The first input terminal of the series transformer is electrically connected to the AC side of the five-level inverter, the second input terminal of the series transformer is electrically connected to the AC side of the corresponding harmonic generation inverter, and the output terminal of the series transformer is electrically connected to the AC output port.

19. The five-level fractal converter according to claim 18, characterized in that, The series transformer includes: a first transformer, a second transformer, and a third transformer; The first terminal of the first transformer is electrically connected to the first terminal of the AC side of the five-level inverter, the second terminal of the first transformer is electrically connected to the first terminal of the AC output port, the third terminal of the first transformer is electrically connected to the neutral point or ground terminal, and the fourth terminal of the first transformer is electrically connected to the first terminal of the AC side of the harmonic generation inverter. The first terminal of the second transformer is electrically connected to the second terminal of the AC side of the five-level inverter, the second terminal of the second transformer is electrically connected to the second terminal of the AC output port, the third terminal of the second transformer is electrically connected to the neutral point or ground terminal, and the fourth terminal of the second transformer is electrically connected to the second terminal of the AC side of the harmonic generation inverter. The first terminal of the third transformer is electrically connected to the third terminal of the AC side of the five-level inverter, the second terminal of the third transformer is electrically connected to the third terminal of the AC output port, the third terminal of the third transformer is electrically connected to the neutral point or ground terminal, and the fourth terminal of the third transformer is electrically connected to the third terminal of the AC side of the harmonic generation inverter.

20. The five-level fractal converter according to claim 18, characterized in that, The series transformer includes: a first single-phase winding, a second single-phase winding, a third single-phase winding, and a sixth winding; The first single-phase winding, the second single-phase winding, and the third single-phase winding are electrically coupled to the sixth winding; The first end of the first single-phase winding is electrically connected to the first end of the AC side of the five-level inverter, and the second end of the first single-phase winding is electrically connected to the first end of the AC output port. The first end of the second single-phase winding is electrically connected to the second end of the AC side of the five-level inverter, and the second end of the second single-phase winding is electrically connected to the second end of the AC output port. The first end of the third single-phase winding is electrically connected to the third end of the AC side of the five-level inverter, and the second end of the third single-phase winding is electrically connected to the third end of the AC output port. The sixth winding is electrically connected to the first terminal, the second terminal, and the third terminal of the AC side of the corresponding harmonic generating inverter.

21. The five-level fractal converter according to any one of claims 1-13, characterized in that, The five-level fractal converter also includes: A first filter, the first end of which is electrically connected to the AC side of the five-level inverter, and the second end of which is electrically connected to the first input end of the fractal connector module; And / or, a second filter, the first end of which is electrically connected to the AC side of the corresponding harmonic generating inverter, and the second end of which is electrically connected to the corresponding second input terminal in the fractal connector module.

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