High-voltage fractal converter

Abstract

The invention discloses a high-voltage fractal converter, and relates to the technical field of AC / DC converters. The high-voltage fractal converter comprises an inversion module, the inversion module comprises N inverters, the direct current sides of the N inverters are electrically connected with N first direct current power supply ports in a one-to-one correspondence mode, the N first direct current power supply ports are sequentially connected in series, the N inverters are used for outputting alternating current electric signals, and the alternating current electric signals comprise first harmonic signals in a higher harmonic interval; the harmonic generation module comprises a harmonic generation inverter, the direct current side of the harmonic generation inverter is electrically connected with the second direct current power supply port, and the harmonic generation inverter is used for outputting a corresponding second harmonic signal according to the first harmonic signal; the N first input ends of the fractal connector module are electrically connected with the alternating current sides of the N inverters in a one-to-one correspondence mode, the second input end of the fractal connector module is electrically connected with the alternating current side of the 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, harmonic signals of N inverters can be compensated.

Description

Technical Field

[0001] This application belongs to the field of AC / DC converter technology, and particularly relates to a high-voltage 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. Two-level and three-level converters are currently commonly used power electronic converters in engineering. They can be extended to higher voltage levels through device series technology and have advantages such as simple structure and simple control.

[0004] However, in existing AC / DC converter technologies, the switching frequency of two-level / three-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 of the converter. Therefore, how to effectively reduce the switching frequency of the converter and improve its overall output capacity 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 high-voltage fractal converter that can effectively compensate for the harmonic signals of the high-voltage fractal converter, thereby helping to reduce the switching frequency of N inverters and improve the overall output capacity of the converter.

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

[0007] The inverter module includes N inverters, where N > 1 and N is a positive integer. The DC side of the N inverters is electrically connected to N first DC power supply ports in a one-to-one correspondence. The N first DC power supply ports are connected in series. The N inverters are used to output AC signals, which include first harmonic signals in the higher harmonic range.

[0008] The harmonic generation module includes a harmonic generation inverter, the DC side of which is electrically connected to a second DC power supply port. The harmonic generation inverter is used to output a corresponding second harmonic signal based on the first harmonic signal.

[0009] The fractal connector module has N first input terminals that are electrically connected to the AC sides of N inverters one by one, the second input terminal of the fractal connector module is electrically connected to the AC side of the harmonic generation inverter, and the output terminal of the fractal connector module is electrically connected to the 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 k-th inverter among the N inverters includes: at least one supporting capacitor and a three-phase inverter bridge, 1≤k≤N, where k is a positive integer;

[0015] At least one supporting capacitor is connected in series between the kth first DC power supply ports;

[0016] The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, and a sixth switching unit;

[0017] The first terminal of the first switching unit, the first terminal of the third switching unit, and the first terminal of the fifth switching unit are electrically connected to the positive terminal of the k-th first DC power supply port;

[0018] The second end of the first switch unit and the first end of the second switch unit are electrically connected to the midpoint of the first bridge arm; the second end of the third switch unit and the first end of the fourth switch unit are electrically connected to the midpoint of the second bridge arm; and the second end of the fifth switch unit and the first end of the sixth switch unit are electrically connected to the midpoint of the third bridge arm.

[0019] The second terminal of the second switching unit, the second terminal of the fourth switching unit, and the second terminal of the sixth switching unit are electrically connected to the negative terminal of the k-th first DC power supply port;

[0020] The midpoints of the first, second, and third bridge arms are connected to the AC side of the k-th inverter.

[0021] In some possible implementations, the k-th inverter among the N inverters includes: a first supporting capacitor, a second supporting capacitor, and a three-phase inverter bridge, where 1 ≤ k ≤ N, and k is a positive integer;

[0022] The first terminal of the first supporting capacitor is electrically connected to the positive terminal of the kth first DC power supply port, the second terminal of the first supporting capacitor and the first terminal of the second supporting capacitor are electrically connected to the neutral point, and the second terminal of the second supporting capacitor is electrically connected to the negative terminal of the kth first DC power supply port.

[0023] The three-phase inverter bridge includes: the first switching unit, the second switching unit, the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the seventh switching unit, the eighth switching unit, the ninth switching unit, the tenth switching unit, the eleventh switching unit, the twelfth switching unit, the thirteenth switching unit, the fourteenth switching unit, the fifteenth switching unit, the sixteenth switching unit, the seventeenth switching unit, and the eighteenth switching unit;

[0024] The first, second, third, and fourth switch units are connected in series between the k-th first DC power supply port. The first and second switch units are electrically connected to the first node, the second and third switch units are electrically connected to the midpoint of the first bridge arm, and the third and fourth switch units are electrically connected to the second node. The first end of the fifth switch unit is electrically connected to the first node, the second end of the fifth switch unit and the first end of the sixth switch unit are electrically connected to the neutral point, and the second end of the sixth switch unit is electrically connected to the second node.

[0025] The seventh, eighth, ninth, and tenth switch units are connected in series between the kth first DC power supply ports. The seventh and eighth switch units are electrically connected to the third node, the eighth and ninth switch units are electrically connected to the midpoint of the second bridge arm, and the ninth and tenth switch units are electrically connected to the fourth node. The first end of the eleventh switch unit is electrically connected to the third node, the second end of the eleventh switch unit and the first end of the twelfth switch unit are electrically connected to the neutral point, and the second end of the twelfth switch unit is electrically connected to the fourth node.

[0026] The thirteenth, fourteenth, fifteenth, and sixteenth switch units are connected in series between the kth first DC power supply ports. The thirteenth and fourteenth switch units are electrically connected to the fifth node, the fourteenth and fifteenth switch units are electrically connected to the midpoint of the third bridge arm, and the fifteenth and sixteenth switch units are electrically connected to the sixth node. The first end of the seventeenth switch unit is electrically connected to the fifth node, the second end of the seventeenth switch unit and the first end of the eighteenth switch unit are electrically connected to the neutral point, and the second end of the eighteenth switch unit is electrically connected to the sixth node.

[0027] The midpoints of the first, second, and third bridge arms are connected to the AC side of the k-th inverter.

[0028] In some possible implementations, the k-th inverter among the N inverters includes: a first supporting capacitor, a second supporting capacitor, and a three-phase inverter bridge, where 1 ≤ k ≤ N, and k is a positive integer;

[0029] The first terminal of the first supporting capacitor is electrically connected to the positive terminal of the kth first DC power supply port, the second terminal of the first supporting capacitor and the first terminal of the second supporting capacitor are electrically connected to the neutral point, and the second terminal of the second supporting capacitor is electrically connected to the negative terminal of the kth first DC power supply port.

[0030] The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit, as well as a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode;

[0031] The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are connected in series between the kth first DC power supply port. The first switch unit and the second switch unit are electrically connected to the first node, the second switch unit and the third switch unit are electrically connected to the midpoint of the first bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node. The cathode of the first diode is electrically connected to the first node, the anode of the first diode and the cathode of the second diode are electrically connected to the neutral point, and the anode of the second diode is electrically connected to the second node.

[0032] The fifth, sixth, seventh, and eighth switch units are connected in series between the kth first DC power supply port. The fifth and sixth switch units are electrically connected to the third node, the sixth and seventh switch units are electrically connected to the midpoint of the second bridge arm, and the seventh and eighth switch units are electrically connected to the fourth node. The cathode of the third diode is electrically connected to the third node, the anode of the third diode and the cathode of the fourth diode are electrically connected to the neutral point, and the anode of the fourth diode is electrically connected to the fourth node.

[0033] The ninth, tenth, eleventh, and twelfth switch units are connected in series between the kth first DC power supply ports. The ninth and tenth switch units are electrically connected to the fifth node, the tenth and eleventh switch units are electrically connected to the midpoint of the third bridge arm, and the eleventh and twelfth switch units are electrically connected to the sixth node. The cathode of the first diode is electrically connected to the fifth node, the anode of the first diode and the cathode of the second diode are electrically connected to the neutral point, and the anode of the second diode is electrically connected to the sixth node.

[0034] The midpoints of the first, second, and third bridge arms are connected to the AC side of the k-th inverter.

[0035] In some possible implementations, the k-th inverter among the N inverters includes: a first supporting capacitor, a second supporting capacitor, and a three-phase inverter bridge, where 1 ≤ k ≤ N, and k is a positive integer;

[0036] The first terminal of the first supporting capacitor is electrically connected to the positive terminal of the kth first DC power supply port, the second terminal of the first supporting capacitor and the first terminal of the second supporting capacitor are electrically connected to the neutral point, and the second terminal of the second supporting capacitor is electrically connected to the negative terminal of the kth first DC power supply port.

[0037] The three-phase inverter bridge includes: the first switching unit, the second switching unit, the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the seventh switching unit, the eighth switching unit, the ninth switching unit, the tenth switching unit, the eleventh switching unit, and the twelfth switching unit;

[0038] The first terminal of the first switch unit, the first terminal of the fifth switch unit, and the first terminal of the ninth switch unit are electrically connected to the positive terminal of the kth first DC power supply port. The second terminal of the first switch unit and the first terminal of the fourth switch unit are electrically connected to the midpoint of the first bridge arm. The second terminal of the fifth switch unit and the first terminal of the eighth switch unit are electrically connected to the midpoint of the second bridge arm. The second terminal of the ninth switch unit and the first terminal of the twelfth switch unit are electrically connected to the midpoint of the third bridge arm.

[0039] The first terminal of the second switching unit is electrically connected to the neutral point; the second terminal of the second switching unit is electrically connected to the second terminal of the third switching unit; the first terminal of the third switching unit is electrically connected to the midpoint of the first bridge arm. The first terminal of the sixth switching unit is electrically connected to the neutral point; the second terminal of the sixth switching unit is electrically connected to the second terminal of the seventh switching unit; the first terminal of the seventh switching unit is electrically connected to the midpoint of the second bridge arm. The first terminal of the tenth switching unit is electrically connected to the neutral point; the second terminal of the tenth switching unit is electrically connected to the second terminal of the eleventh switching unit; the first terminal of the eleventh switching unit is electrically connected to the midpoint of the third bridge arm.

[0040] The midpoints of the first, second, and third bridge arms are connected to the AC side of the k-th inverter.

[0041] In some possible implementations, the k-th inverter among the N inverters includes: at least one supporting capacitor and a three-phase inverter bridge, 1≤k≤N, where k is a positive integer;

[0042] At least one supporting capacitor is connected in series between the kth first DC power supply ports;

[0043] The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit, as well as a first capacitor, a second capacitor, and a third capacitor;

[0044] The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are connected in series between the kth first DC power supply port. The first switch unit and the second switch unit are electrically connected to the first node. The second switch unit and the third switch unit are electrically connected to the midpoint of the first bridge arm. The third switch unit and the fourth switch unit are electrically connected to the second node. The first capacitor is electrically connected between the first node and the second node.

[0045] The fifth, sixth, seventh, and eighth switch units are connected in series between the kth first DC power supply port. The fifth and sixth switch units are electrically connected to the third node, the sixth and seventh switch units are electrically connected to the midpoint of the second bridge arm, and the seventh and eighth switch units are electrically connected to the fourth node. The second capacitor is electrically connected between the third and fourth nodes.

[0046] The ninth, tenth, eleventh, and twelfth switch units are connected in series between the kth first DC power supply port. The ninth and tenth switch units are electrically connected to the fifth node, the tenth and eleventh switch units are electrically connected to the midpoint of the third bridge arm, and the eleventh and twelfth switch units are electrically connected to the sixth node. The third capacitor is electrically connected between the fifth and sixth nodes.

[0047] The midpoints of the first, second, and third bridge arms are connected to the AC side of the k-th inverter.

[0048] In some possible implementations, the N inverters include 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;

[0049] In any given switching unit, multiple semiconductor power switching units are connected in series.

[0050] And / or, multiple semiconductor power switching units in any switching unit are connected in parallel with each other.

[0051] In some possible implementations, the semiconductor switching unit in any switching unit of the kth inverter among the N inverters includes an IGCT;

[0052] The k-th inverter also includes a clamping circuit disposed between the k-th first DC power supply ports.

[0053] In some possible implementations, the fractal connector module includes N+1 three-phase dual-winding transformers;

[0054] In the N+1 three-phase double-winding transformers, the input terminals of the first to Nth three-phase double-winding transformers are electrically connected to the AC side of the N inverters one by one, the input terminal of the N+1th three-phase double-winding transformer is electrically connected to the AC side of the harmonic generation inverter, and the output terminals of the N+1th three-phase double-winding transformers are electrically connected to the AC output port through the AC busbar.

[0055] Alternatively, the fractal connector module includes N three-phase dual-winding transformers and connection components;

[0056] The input terminals of N three-phase double-winding transformers are electrically connected one-to-one with the AC sides of N inverters. The output terminals of the N three-phase double-winding transformers are electrically connected to the AC output ports through the AC busbar. The AC side of the harmonic generation inverter is electrically connected to the AC busbar through the connecting components.

[0057] In some possible implementations, the fractal connector module includes a three-phase multi-winding transformer;

[0058] A three-phase multi-winding transformer includes N+1 first windings and 1 second winding, with the N+1 first windings and the second windings coupled together.

[0059] In the N+1 first windings, the first to Nth first windings are electrically connected to the AC side of the N inverters one by one, the N+1th first winding is electrically connected to the AC side of the harmonic generation inverter, and the second winding is electrically connected to the AC output port.

[0060] Alternatively, a three-phase multi-winding transformer includes N first windings and 1 second winding, with the N first windings and the second winding coupled together. The fractal connector module also includes connecting components.

[0061] The N first windings are electrically connected to the AC sides of the N inverters one by one, the second windings are electrically connected to the AC output ports, and the AC side of the harmonic generation inverter is electrically connected to the AC output ports through connecting components.

[0062] In some possible implementations, the fractal connector module includes: L three-phase multi-winding transformers, 1≤L≤N, where L is a positive integer, each of the L three-phase multi-winding transformers includes at least one first winding and one second winding, and the first winding and the second winding in the same three-phase multi-winding transformer are coupled together.

[0063] The L three-phase multi-winding transformers include N first windings. The N first windings of the L three-phase multi-winding transformers are electrically connected to the AC side of the N inverters one by one. The L second windings of the L three-phase multi-winding transformers are electrically connected to the AC output port through the AC busbar.

[0064] The fractal connector module also includes a three-phase dual-winding transformer or connecting components;

[0065] The AC side of the harmonic generating inverter is electrically connected to the AC busbar via a three-phase dual-winding transformer, or the AC side of the harmonic generating inverter is electrically connected to the AC busbar via a connecting component, so as to be electrically connected to the AC output port via the AC busbar.

[0066] In some possible implementations, the fractal connector module includes a three-phase multi-winding transformer and a series transformer;

[0067] A three-phase multi-winding transformer includes N first windings and 1 second winding, with the N first windings and the second winding being coupled together.

[0068] The N first windings are electrically connected to the AC side of the N inverters one by one, and the second windings are electrically connected to the first input terminal of the series transformer.

[0069] The AC side of the harmonic generator inverter is electrically connected to the second input terminal of the series transformer, and the output terminal of the series transformer is electrically connected to the AC output port.

[0070] In some possible implementations, the fractal connector module includes N three-phase dual-winding transformers and series transformers;

[0071] The input terminals of N three-phase double-winding transformers are electrically connected one-to-one with the AC side of N inverters, and the output terminals of N three-phase double-winding transformers are electrically connected to the first input terminal of the series transformer through the AC busbar.

[0072] The AC side of the harmonic generator inverter is electrically connected to the second input terminal of the series transformer, and the output terminal of the series transformer is electrically connected to the AC output port.

[0073] In some possible implementations, the fractal connector module includes: L three-phase multi-winding transformers and 1 series transformer, 1≤L≤N, where L is a positive integer. Each of the L three-phase multi-winding transformers includes at least one first winding and one second winding, and the first winding and the second winding in the same three-phase multi-winding transformer are coupled together.

[0074] The L three-phase multi-winding transformers include N first windings. The N first windings of the L three-phase multi-winding transformers are electrically connected to the AC side of the N inverters one by one. The L second windings of the L three-phase multi-winding transformers are electrically connected to the first input terminal of the series transformer through the AC busbar.

[0075] The AC side of the harmonic generator inverter is electrically connected to the second input terminal of the series transformer, and the output terminal of the series transformer is electrically connected to the AC output port.

[0076] In some possible implementations, the series transformer includes: a first transformer, a second transformer, and a third transformer;

[0077] The first terminal of the first transformer is electrically connected to the first terminal of the first input terminal of the series transformer, 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.

[0078] The first terminal of the second transformer is electrically connected to the second terminal of the first input terminal of the series transformer, 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.

[0079] The first terminal of the third transformer is electrically connected to the third terminal of the first input terminal of the series transformer; 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.

[0080] 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 third winding;

[0081] The first single-phase winding, the second single-phase winding, and the third single-phase winding are electrically coupled to the third winding;

[0082] The first end of the first single-phase winding is electrically connected to the first end of the first input terminal of the series transformer, and the second end of the first single-phase winding is electrically connected to the first end of the AC output port.

[0083] The first end of the second single-phase winding is electrically connected to the second end of the first input end of the series transformer, and the second end of the second single-phase winding is electrically connected to the second end of the AC output port.

[0084] The first end of the third single-phase winding is electrically connected to the third end of the first input terminal of the series transformer, and the second end of the third single-phase winding is electrically connected to the third end of the AC output port.

[0085] The third 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.

[0086] In some possible implementations, the high-voltage fractal converter further includes:

[0087] The first filter has its first end electrically connected to the AC side of the kth inverter among the N inverters, and its second end electrically connected to the corresponding first input end in the fractal connector module, where 1≤k≤N and k is a positive integer.

[0088] 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 second input terminal in the fractal connector module.

[0089] This application provides a high-voltage fractal converter, which includes an inverter module, a harmonic generation module, and a fractal connector module. The inverter module includes N inverters, each with its DC side electrically connected to one of N first DC power supply ports, which are connected in series. The N inverters output AC signals, including first harmonic signals within the higher harmonic range. The harmonic generation module includes a harmonic generation inverter, whose DC side is electrically connected to a second DC power supply port. The harmonic generation inverter outputs a corresponding second harmonic signal based on the first harmonic signal. The fractal connector module has N first input terminals electrically connected to the AC sides of the N inverters, a second input terminal connected to the AC side of the harmonic generation inverter, and an output terminal connected to an AC output port. The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module.

[0090] As described above, in the high-voltage fractal converter provided in this application embodiment, on the one hand, the DC ports of N inverters are connected in series, thereby increasing the DC side voltage level and avoiding the technical difficulties caused by the huge number of series devices in a single inverter under high-voltage applications in traditional solutions. On the other hand, the harmonic generation inverter generates a second harmonic signal based on the first harmonic signal generated by the N inverters, and outputs the second harmonic signal to the fractal connector module. This achieves compensation of the first harmonic signal by the second harmonic signal within the fractal connector module, reducing or even eliminating the harmonics of the output electrical signal from the converter to the AC output port. Thus, based on the harmonic compensation function of the harmonic generation module and the fractal connector module, the switching devices of the N inverters can operate at a lower switching frequency with low switching device losses. Operating the N inverters at a low switching frequency increases the converter's 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

[0091] 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.

[0092] Figure 1 This is a schematic diagram of the structure of a high-voltage fractal converter provided in one embodiment of this application;

[0093] Figure 2 This is a schematic diagram of the structure of an inverter provided in one embodiment of this application;

[0094] Figure 3 This is a schematic diagram of the inverter provided in another embodiment of this application;

[0095] Figure 4 This is a schematic diagram of the inverter provided in another embodiment of this application;

[0096] Figure 5 This is a schematic diagram of the inverter provided in another embodiment of this application;

[0097] Figure 6 This is a schematic diagram of the inverter provided in another embodiment of this application;

[0098] Figure 7 This is a schematic diagram of the structure of a switching unit provided in an embodiment of this application;

[0099] Figure 8 This is a schematic diagram of the structure of a switching unit provided in another embodiment of this application;

[0100] Figure 9 This is a schematic diagram of the structure of a semiconductor power switching unit provided in an embodiment of this application;

[0101] Figure 10 This is a schematic diagram of the structure of a semiconductor power switching unit provided in another embodiment of this application;

[0102] Figure 11 This is a schematic diagram of the structure of a semiconductor power switching unit provided in another embodiment of this application;

[0103] Figure 12 This is a schematic diagram of the structure of a semiconductor power switching unit provided in another embodiment of this application;

[0104] Figure 13 This is a schematic diagram of the structure of a fractal connector module provided in one embodiment of this application;

[0105] Figure 14 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0106] Figure 15 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0107] Figure 16 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0108] Figure 17 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0109] Figure 18 This is a schematic diagram of the structure of a fractal connector module provided in another embodiment of this application;

[0110] Figure 19 This is a schematic diagram of the structure of a series transformer provided in one embodiment of this application;

[0111] Figure 20 This is a schematic diagram of the structure of a series transformer provided in another embodiment of this application;

[0112] Figure 21 This is a schematic diagram of the structure of a high-voltage fractal converter provided in another embodiment of this application;

[0113] Figure 22 This is a schematic diagram of the structure of a harmonic generation inverter provided in one embodiment of this application. Detailed Implementation

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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:

[0122] As mentioned earlier, in existing AC / DC converter technologies, the switching frequency of two-level / three-level converters is relatively high, usually greater than 2kHz / 1kHz, which results in high losses and heat generation of switching devices, leading to low overall output capacity of the converter and high cost per unit capacity.

[0123] The inventors of this application have discovered that, in traditional technical solutions, increasing the output capacity of the converter requires multiple two-level converters connected in parallel, which significantly increases the overall cost. Alternatively, if traditional technical solutions increase the output capacity by reducing the switching frequency of the converter and decreasing the losses of the switching devices, a large inductor-capacitor filter is required to passively filter out high-order harmonic components. Since the harmonic components generated at low switching frequencies are large, a large passive filter is required, leading to a rapid increase in cost.

[0124] Therefore, traditional two-level / three-level converters currently suffer from high switching frequencies, typically greater than 2kHz / 1kHz, leading to high switching device losses, high heat generation, low overall converter output capacity, and high cost per unit capacity. Furthermore, traditional two-level / three-level converters with series-connected components present challenges such as a large number of components in series, difficulty in voltage equalization, and high AC side voltage variation rate. Therefore, effectively reducing the converter's switching frequency and increasing its overall output capacity has become a pressing technical problem for those skilled in the art.

[0125] In view of the above, in order to solve the problems of the prior art, this application provides a high-voltage fractal converter. It should be noted that the embodiments provided in this application are not intended to limit the scope of this application.

[0126] The high-voltage 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 high-voltage fractal converter 100 provided in one embodiment of this application. Figure 1 As shown, this application embodiment provides a high-voltage fractal converter 100, which includes:

[0127] Inverter module 10 includes N inverters, where N > 1 and N is a positive integer. The DC side of each of the N inverters is electrically connected to one of the N first DC power supply ports. The N first DC power supply ports are connected in series. The N inverters are used to output AC signals, which include first harmonic signals in the higher harmonic range.

[0128] The harmonic generation module 20 includes a harmonic generation inverter 21. The DC side of the harmonic generation inverter 21 is electrically connected to the second DC power supply port. The harmonic generation inverter 21 is used to output a corresponding second harmonic signal according to the first harmonic signal.

[0129] The fractal connector module 30 has N first input terminals that are electrically connected to the AC sides of N inverters one by one, the second input terminal of the fractal connector module 30 is electrically connected to the AC side of the harmonic generating inverter 21, and the output terminal of the fractal connector module 30 is electrically connected to the AC output port.

[0130] The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module 30.

[0131] Specifically, for example, the inverter module 10 includes inverter 1, inverter 2, ..., inverter N. The first DC power supply ports 1 to N of these inverters are connected in series, thereby improving the DC side voltage level and avoiding the technical difficulties caused by the huge number of series devices in a single inverter under high voltage level applications in traditional solutions.

[0132] N inverters comprise multiple switching units. By reducing the switching frequency of each switching unit, the device losses of the switching units in the N inverters can be reduced, thereby enabling the N inverters to output greater power. For any inverter k (1≤k≤N), its connected DC port is the corresponding first DC power supply port k, and its AC side can be named AC port k. Inverter k can be a two-level inverter or a three-level inverter.

[0133] In this embodiment, the switching devices in the N inverters operate at a lower switching frequency to generate a fundamental voltage and current of 50Hz. Taking inverter k as an example, when inverter k is a two-level inverter, the switching frequency is typically less than 1000Hz, with typical values ​​of 50Hz, 150Hz, and also 250Hz, 350Hz, 450Hz, 550Hz, 650Hz, 750Hz, 850Hz, or 950Hz. When inverter k is a three-level inverter, the switching frequency is typically less than 500Hz, with typical values ​​of 50Hz, 100Hz, 150Hz, and also 200Hz, 250Hz, 300Hz, 400Hz, or 450Hz. After the switching frequency of the switching unit is reduced, the N inverters output an AC signal, which includes the fundamental signal and the first harmonic signal in the higher harmonic range.

[0134] By reducing the switching frequency of the switching devices in N inverters, device losses are reduced, thereby enabling a greater power output. Compared to traditional two-level or three-level inverter technologies, inverter k can have a capacity several times greater, significantly reducing the cost per unit capacity of N inverters and improving economic efficiency.

[0135] 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.

[0136] 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 N inverters, resulting in lower manufacturing costs. Compared to conventional technologies that use multiple sets of N inverters and passive filters, this application uses the harmonic generation inverter 21 to increase the overall capacity of the converter, achieving lower costs.

[0137] 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 components generated by the N inverters in real time and provides them as control command values ​​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 N inverters.

[0138] The first input terminal of the fractal connector module 30 is electrically connected to the AC side of N inverters, and at least one second input terminal of the fractal connector module 30 is 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.

[0139] In this way, the harmonic voltages and harmonic currents generated by the N inverters and the harmonic generator inverter 21 are canceled out by the fractal connector module 30, so that the voltage and current output from the fractal connector module 30 to the AC output port 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.

[0140] 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.

[0141] In a high-voltage fractal converter 100 according to an embodiment of this application, a power frequency fundamental wave and a high-frequency harmonic are constructed by an inverter module 10 and a harmonic generation module 20, respectively, and a sinusoidal voltage waveform is constructed by 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 a harmonic voltage or 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 a fractal connector module 30 to achieve harmonic cancellation and construct a standard sinusoidal waveform.

[0142] 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 N inverters 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.

[0143] Thus, in a high-voltage 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 N inverters or passive filters with high costs. Through the harmonic compensation effect based on the harmonic generation module 20 and the fractal connector module 30, the switching devices of the N inverters in the inverter module 10 can directly operate at a lower switching frequency with low switching device losses. In this way, the output capacity of the converter can be increased by operating the N inverters at a low switching frequency, thereby significantly reducing the cost per unit capacity of the inverter, while effectively ensuring the reliability and performance of the output signal.

[0144] Furthermore, in this embodiment, the first DC power supply ports 1 to N of inverter 1, inverter 2, ..., inverter N are connected in series, thereby improving the DC side voltage level and avoiding the technical difficulties caused by the huge number of series devices of a single inverter in high-voltage applications in traditional schemes.

[0145] It is also important to note that the fractal connector module 30 in this application mainly includes two types: parallel fractal connector modules and series fractal connector modules. By reasonably setting the transformer phase in the fractal connector module 30, the AC voltage of each inverter in the inverter module 10 can be multiplexed, reducing AC voltage harmonics, optimizing waveform quality, reducing the voltage conversion rate of the AC port, and further reducing the capacity of the harmonic generation module 20.

[0146] Optionally, according to some embodiments of this application, the number of harmonic generation inverters 21 in the harmonic generation module 20 is 1;

[0147] 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.

[0148] 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.

[0149] 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 N inverters. The fundamental signal generated by the N inverters 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.

[0150] 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 signals generated by N inverters include 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.

[0151] In this way, 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 of the N inverters are also reduced, thereby increasing the output power of the high-voltage fractal converter 100 and improving its output capacity. Therefore, this embodiment achieves both a reduction in the switching frequency of the high-voltage fractal converter 100 and an increase in the converter's output capacity.

[0152] Optionally, according to some embodiments of this application, the switching frequency of any harmonic generating inverter 21 is greater than the switching frequencies of N inverters.

[0153] In this embodiment, the switching frequency of any harmonic generating inverter 21 is greater than the switching frequencies of the N inverters. All switching devices in the N inverters operate at a lower switching frequency to generate 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.

[0154] In this way, by reducing the switching frequency of the switching devices in the N inverters, 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 in 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.

[0155] Optionally, according to some embodiments of this application, the number of harmonic generating inverters 21 in the harmonic generating module 20 is n, where n is greater than 1 and n is a positive integer; the AC side of the n harmonic generating inverters 21 is electrically connected to the n second input terminals of the fractal connector module 30 respectively.

[0156] 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;

[0157] 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.

[0158] 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 two-level cascaded inverter 11 that are difficult for the harmonic generating inverter 21 with a smaller number to compensate.

[0159] It should be added that the total amount of second harmonic signals generated by multiple harmonic generating inverters 21 can be the same as that generated when only one harmonic generating inverter 21 is used. Therefore, when using multiple harmonic generating inverters 21, the total capacity of n harmonic generating inverters 21 is the same as that of using only one harmonic generating inverter 21. However, since the capacity of a single harmonic generating inverter 21 is reduced, the manufacturing cost of a single harmonic generating inverter 21 is significantly reduced. Therefore, using multiple harmonic generating inverters 21 results in lower costs.

[0160] Please see below. Figure 2Optionally, according to some embodiments of this application, the k-th inverter among the N inverters includes: at least one supporting capacitor and a three-phase inverter bridge, 1≤k≤N, where k is a positive integer;

[0161] At least one supporting capacitor is connected in series between the kth first DC power supply ports;

[0162] The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, and a sixth switching unit;

[0163] The first terminal of the first switching unit, the first terminal of the third switching unit, and the first terminal of the fifth switching unit are electrically connected to the positive terminal of the k-th first DC power supply port;

[0164] The second end of the first switch unit and the first end of the second switch unit are electrically connected to the midpoint A of the first bridge arm; the second end of the third switch unit and the first end of the fourth switch unit are electrically connected to the midpoint B of the second bridge arm; and the second end of the fifth switch unit and the first end of the sixth switch unit are electrically connected to the midpoint C of the third bridge arm.

[0165] The second terminal of the second switching unit, the second terminal of the fourth switching unit, and the second terminal of the sixth switching unit are electrically connected to the negative terminal of the k-th first DC power supply port;

[0166] The midpoints A of the first bridge arm, B of the second bridge arm, and C of the third bridge arm are connected to the AC side of the k-th inverter.

[0167] In a specific implementation, taking inverter k as an example, the aforementioned at least one supporting capacitor may include a first supporting capacitor Cbus1 and a second supporting capacitor Cbus2. The first supporting capacitor Cbus1 and the second supporting capacitor Cbus2 may each be composed of a single capacitor, or they may 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 k, preventing sudden changes in the DC bus voltage. The capacitance values ​​of each supporting capacitor can also be flexibly set according to actual voltage regulation requirements; this embodiment does not impose strict limitations on this.

[0168] And, combined Figure 2 As shown in the first switch unit 110, Figure 2 Each switching unit in the diagram is illustrated using a switching device and a freewheeling diode connected in reverse parallel with it. The switching devices in the first, second, third, fourth, fifth, and sixth switching units are, for example... Figure 2 The S1 to S6 in the circuit include freewheeling diodes such as D1 to D6, but this does not mean that the above-mentioned switching units only contain these devices.

[0169] 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.

[0170] The switching devices included in the switching units of the aforementioned N inverters operate at a low switching frequency, typically less than 1000Hz, with typical values ​​of 50Hz, 150Hz, or 250Hz, 350Hz, 450Hz, 550Hz, 650Hz, 750Hz, 850Hz, or 950Hz. Their main purpose is to generate a 50Hz fundamental voltage and current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0171] 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 N inverters to output corresponding AC signals. 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.

[0172] Please see below. Figure 3 Optionally, according to some embodiments of this application, the k-th inverter among the N inverters includes: a first supporting capacitor Cbus1, a second supporting capacitor Cbus2, and a three-phase inverter bridge, where 1≤k≤N and k is a positive integer;

[0173] The first terminal of the first supporting capacitor Cbus1 is electrically connected to the positive terminal of the kth first DC power supply port, the second terminal of the first supporting capacitor Cbus1 and the first terminal of the second supporting capacitor Cbus2 are electrically connected to the neutral point N, and the second terminal of the second supporting capacitor Cbus2 is electrically connected to the negative terminal of the kth first DC power supply port.

[0174] The three-phase inverter bridge includes: the first switching unit, the second switching unit, the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the seventh switching unit, the eighth switching unit, the ninth switching unit, the tenth switching unit, the eleventh switching unit, the twelfth switching unit, the thirteenth switching unit, the fourteenth switching unit, the fifteenth switching unit, the sixteenth switching unit, the seventeenth switching unit, and the eighteenth switching unit;

[0175] The first, second, third, and fourth switch units are connected in series between the k-th first DC power supply port. The first and second switch units are electrically connected to the first node N1, the second and third switch units are electrically connected to the midpoint A of the first bridge arm, and the third and fourth switch units are electrically connected to the second node N2. The first end of the fifth switch unit is electrically connected to the first node N1, the second end of the fifth switch unit and the first end of the sixth switch unit are electrically connected to the neutral point N, and the second end of the sixth switch unit is electrically connected to the second node N2.

[0176] The seventh, eighth, ninth, and tenth switch units are connected in series between the kth first DC power supply ports. The seventh and eighth switch units are electrically connected to the third node N3, the eighth and ninth switch units are electrically connected to the midpoint B of the second bridge arm, and the ninth and tenth switch units are electrically connected to the fourth node N4. The first end of the eleventh switch unit is electrically connected to the third node N3, the second end of the eleventh switch unit and the first end of the twelfth switch unit are electrically connected to the neutral point N, and the second end of the twelfth switch unit is electrically connected to the fourth node N4.

[0177] The thirteenth, fourteenth, fifteenth, and sixteenth switch units are connected in series between the kth first DC power supply ports. The thirteenth and fourteenth switch units are electrically connected to the fifth node N5, the fourteenth and fifteenth switch units are electrically connected to the midpoint C of the third bridge arm, and the fifteenth and sixteenth switch units are electrically connected to the sixth node N6. The first end of the seventeenth switch unit is electrically connected to the fifth node N5, the second end of the seventeenth switch unit and the first end of the eighteenth switch unit are electrically connected to the neutral point N, and the second end of the eighteenth switch unit is electrically connected to the sixth node N6.

[0178] The midpoints A of the first bridge arm, B of the second bridge arm, and C of the third bridge arm are connected to the AC side of the k-th inverter.

[0179] 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 k, and to prevent sudden changes in the DC bus voltage. The capacitance values ​​of the above-mentioned supporting capacitors can also be flexibly set according to the actual voltage regulation requirements, and this embodiment does not impose strict limitations on them.

[0180] And, combined Figure 3 As shown in the first switch unit 110, Figure 3 Each switching unit in the diagram is illustrated using a switching device and a freewheeling diode connected in reverse parallel with it. The switching devices in the aforementioned first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, and eighteenth switching units are, for example... Figure 3 The S1 to S18 in the circuit include freewheeling diodes such as D1 to D18, but this does not mean that the above-mentioned switching units only contain these devices.

[0181] The switching devices in the switching units of the aforementioned N inverters operate at relatively low switching frequencies. When inverter k is a three-level inverter, the switching frequency is typically less than 500Hz, with typical values ​​being 50Hz, 100Hz, and 150Hz. It can also be 200Hz, 250Hz, 300Hz, 400Hz, or 450Hz. Its main purpose is to generate a 50Hz fundamental voltage and current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0182] 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 N inverters to output corresponding AC signals. 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.

[0183] Please see below. Figure 4 Optionally, according to some embodiments of this application, the k-th inverter among the N inverters includes: a first supporting capacitor Cbus1, a second supporting capacitor Cbus2, and a three-phase inverter bridge, where 1≤k≤N and k is a positive integer;

[0184] The first terminal of the first supporting capacitor Cbus1 is electrically connected to the positive terminal of the kth first DC power supply port, the second terminal of the first supporting capacitor Cbus1 and the first terminal of the second supporting capacitor Cbus2 are electrically connected to the neutral point N, and the second terminal of the second supporting capacitor Cbus2 is electrically connected to the negative terminal of the kth first DC power supply port.

[0185] The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit, as well as a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode;

[0186] The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are connected in series between the kth first DC power supply port. 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 first bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node N2. The cathode of the first diode is electrically connected to the first node N1, the anode of the first diode and the cathode of the second diode are electrically connected to the neutral point N, and the anode of the second diode is electrically connected to the second node N2.

[0187] The fifth, sixth, seventh, and eighth switch units are connected in series between the kth first DC power supply port. The fifth and sixth switch units are electrically connected to the third node N3, the sixth and seventh switch units are electrically connected to the midpoint B of the second bridge arm, and the seventh and eighth switch units are electrically connected to the fourth node N4. The cathode of the third diode is electrically connected to the third node N3, the anode of the third diode and the cathode of the fourth diode are electrically connected to the neutral point N, and the anode of the fourth diode is electrically connected to the fourth node N4.

[0188] The ninth, tenth, eleventh, and twelfth switch units are connected in series between the kth first DC power supply ports. The ninth and tenth switch units are electrically connected to the fifth node N5, the tenth and eleventh switch units are electrically connected to the midpoint C of the third bridge arm, and the eleventh and twelfth switch units are electrically connected to the sixth node N6. The cathode of the first diode is electrically connected to the fifth node N5, the anode of the first diode and the cathode of the second diode are electrically connected to the neutral point N, and the anode of the second diode is electrically connected to the sixth node N6.

[0189] The midpoints A of the first bridge arm, B of the second bridge arm, and C of the third bridge arm are connected to the AC side of the k-th inverter.

[0190] 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 k, and to prevent sudden changes in the DC bus voltage. The capacitance values ​​of the above-mentioned supporting capacitors can also be flexibly set according to the actual voltage regulation requirements, and this embodiment does not impose strict limitations on them.

[0191] And, combined Figure 4 As shown in the first switch unit 110, Figure 4 Each switching unit in the diagram is illustrated using a switching device and a freewheeling diode connected in reverse parallel with it, but this does not mean that the switching units mentioned above contain only these devices.

[0192] And, in Figure 4 In this embodiment, the first diode is, for example, D5; the second diode is, for example, D6; the third diode is, for example, D11; the fourth diode is, for example, D12; the fifth diode is, for example, D17; and the sixth diode is, for example, D18.

[0193] It should be added that, in this embodiment, the number of diodes set between nodes (e.g., between the first node N1 and the second node N2) is not strictly limited, and can be determined according to the actual inverter requirements.

[0194] The switching devices in the switching units of the aforementioned N inverters operate at relatively low switching frequencies. When inverter k is a three-level inverter, the switching frequency is typically less than 500Hz, with typical values ​​being 50Hz, 100Hz, and 150Hz. It can also be 200Hz, 250Hz, 300Hz, 400Hz, or 450Hz. Its main purpose is to generate a 50Hz fundamental voltage and current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0195] 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 N inverters to output corresponding AC signals. 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.

[0196] Please see below. Figure 5 Optionally, according to some embodiments of this application, the k-th inverter among the N inverters includes: a first supporting capacitor Cbus1, a second supporting capacitor Cbus2, and a three-phase inverter bridge, where 1≤k≤N and k is a positive integer;

[0197] The first terminal of the first supporting capacitor Cbus1 is electrically connected to the positive terminal of the kth first DC power supply port, the second terminal of the first supporting capacitor Cbus1 and the first terminal of the second supporting capacitor Cbus2 are electrically connected to the neutral point N, and the second terminal of the second supporting capacitor Cbus2 is electrically connected to the negative terminal of the kth first DC power supply port.

[0198] The three-phase inverter bridge includes: the first switching unit, the second switching unit, the third switching unit, the fourth switching unit, the fifth switching unit, the sixth switching unit, the seventh switching unit, the eighth switching unit, the ninth switching unit, the tenth switching unit, the eleventh switching unit, and the twelfth switching unit;

[0199] The first end of the first switch unit, the first end of the fifth switch unit, and the first end of the ninth switch unit are electrically connected to the positive terminal of the kth first DC power supply port. The second end of the first switch unit and the first end of the fourth switch unit are electrically connected to the midpoint A of the first bridge arm. The second end of the fifth switch unit and the first end of the eighth switch unit are electrically connected to the midpoint B of the second bridge arm. The second end of the ninth switch unit and the first end of the twelfth switch unit are electrically connected to the midpoint C of the third bridge arm.

[0200] The first terminal of the second switching unit is electrically connected to the neutral point N; the second terminal of the second switching unit is electrically connected to the second terminal of the third switching unit; the first terminal of the third switching unit is electrically connected to the midpoint A of the first bridge arm; the first terminal of the sixth switching unit is electrically connected to the neutral point N; the second terminal of the sixth switching unit is electrically connected to the second terminal of the seventh switching unit; the first terminal of the seventh switching unit is electrically connected to the midpoint B of the second bridge arm; the first terminal of the tenth switching unit is electrically connected to the neutral point N; the second terminal of the tenth switching unit is electrically connected to the second terminal of the eleventh switching unit; the first terminal of the eleventh switching unit is electrically connected to the midpoint C of the third bridge arm.

[0201] The midpoints A of the first bridge arm, B of the second bridge arm, and C of the third bridge arm are connected to the AC side of the k-th inverter.

[0202] 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 k, and to prevent sudden changes in the DC bus voltage. The capacitance values ​​of the above-mentioned supporting capacitors can also be flexibly set according to the actual voltage regulation requirements, and this embodiment does not impose strict limitations on them.

[0203] And, combined Figure 5 As shown in the first switch unit 110, Figure 5Each switching unit in the diagram is illustrated using a switching device and a freewheeling diode connected in reverse parallel with it. The switching devices in the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth switching units are, for example... Figure 5 The S1 to S12 in the circuit, and the freewheeling diodes, such as D1 to D12, are not included in the above-mentioned switching units. However, this does not mean that the above-mentioned switching units only contain these devices.

[0204] The switching devices in the switching units of the aforementioned N inverters operate at relatively low switching frequencies. When inverter k is a three-level inverter, the switching frequency is typically less than 500Hz, with typical values ​​being 50Hz, 100Hz, and 150Hz. It can also be 200Hz, 250Hz, 300Hz, 400Hz, or 450Hz. Its main purpose is to generate a 50Hz fundamental voltage and current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0205] 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 N inverters to output corresponding AC signals. 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.

[0206] Please see below. Figure 6 Optionally, according to some embodiments of this application, the k-th inverter among the N inverters includes: at least one supporting capacitor and a three-phase inverter bridge, 1≤k≤N, where k is a positive integer;

[0207] At least one supporting capacitor is connected in series between the kth first DC power supply ports;

[0208] The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit, as well as a first capacitor C1, a second capacitor C2, and a third capacitor C3;

[0209] The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are connected in series between the kth first DC power supply port. 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 first bridge arm. The third switch unit and the fourth switch unit are electrically connected to the second node N2. The first capacitor C1 is electrically connected between the first node N1 and the second node N2.

[0210] The fifth, sixth, seventh, and eighth switch units are connected in series between the kth first DC power supply port. The fifth and sixth switch units are electrically connected to the third node N3, the sixth and seventh switch units are electrically connected to the midpoint B of the second bridge arm, and the seventh and eighth switch units are electrically connected to the fourth node N4. The second capacitor C2 is electrically connected between the third node N3 and the fourth node N4.

[0211] The ninth, tenth, eleventh, and twelfth switch units are connected in series between the kth first DC power supply port. The ninth and tenth switch units are electrically connected to the fifth node N5, the tenth and eleventh switch units are electrically connected to the midpoint C of the third bridge arm, and the eleventh and twelfth switch units are electrically connected to the sixth node N6. The third capacitor C3 is electrically connected between the fifth node N5 and the sixth node N6.

[0212] The midpoints A of the first bridge arm, B of the second bridge arm, and C of the third bridge arm are connected to the AC side of the k-th inverter.

[0213] 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 k, and to prevent sudden changes in the DC bus voltage. The capacitance values ​​of the above-mentioned supporting capacitors can also be flexibly set according to the actual voltage regulation requirements, and this embodiment does not impose strict limitations on them.

[0214] And, combined Figure 6 As shown in the first switch unit 110, Figure 6 Each switching unit in the diagram is illustrated using a switching device and a freewheeling diode connected in reverse parallel with it. The switching devices in the first, second, third, fourth, fifth, sixth, seventh, and eighth switching units are, for example... Figure 6The S1 to S8 in the circuit include freewheeling diodes such as D1 to D8, but this does not mean that the above-mentioned switching units only contain these devices.

[0215] 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 second node N2) is not strictly limited, and can be determined according to the actual inverter requirements.

[0216] The switching devices in the switching units of the aforementioned N inverters operate at relatively low switching frequencies. When inverter k is a three-level inverter, the switching frequency is typically less than 500Hz, with typical values ​​being 50Hz, 100Hz, and 150Hz. It can also be 200Hz, 250Hz, 300Hz, 400Hz, or 450Hz. Its main purpose is to generate a 50Hz fundamental voltage and current, thereby reducing switching losses and increasing output capacity through low-frequency switching operation.

[0217] 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 N inverters to output corresponding AC signals. 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.

[0218] It should be added that, among N inverters, different inverters can adopt the above-mentioned methods. Figures 2 to 6 The structure shown may be any one of the structures or other structures. The structures of each inverter in the N inverters may be the same or different. This application does not impose strict restrictions here.

[0219] Optionally, according to some embodiments of this application, the N inverters include 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;

[0220] In any given switching unit, multiple semiconductor power switching units are connected in series.

[0221] And / or, multiple semiconductor power switching units in any switching unit are connected in parallel with each other.

[0222] In practical applications, combined with Figures 2 to 6 As shown, each three-phase inverter bridge includes multiple switching units. These switching units can be configured with different connection methods to form different circuit structures.

[0223] 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.

[0224] 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.

[0225] As an example, such as Figure 7 As 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 8 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.

[0226] The following is combined with Figures 9 to 12 The following describes some specific structural examples of the semiconductor power switch unit 1101.

[0227] In some examples, such as Figure 9 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.

[0228] 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. MSThe 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.

[0229] 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.

[0230] 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 9 R in MS Alternatively, 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.

[0231] In other examples, such as Figure 10 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.

[0232] 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.

[0233] 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 MSThis 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 10 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.

[0234] In some other examples, such as Figure 11 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.

[0235] 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.

[0236] 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.

[0237] In some other examples, such as Figure 12 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.

[0238] 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 CS 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.

[0239] 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.

[0240] 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.

[0241] 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.

[0242] Continue as Figures 2 to 6 As shown, optionally, according to some embodiments of this application, the semiconductor switching unit in any switching unit of the kth inverter among N inverters includes an IGCT;

[0243] The k-th inverter also includes a clamping circuit disposed between the k-th 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.

[0244] by Figure 2 For example, Figure 2 In inverter k, the clamping circuit includes anode reactance Lbuf, clamping diode Dbuf, clamping resistor Rbuf, and clamping capacitor Cbuf.

[0245] 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.

[0246] Specifically, when any of the multiple switching units of inverter k includes 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.

[0247] 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 N inverters. Therefore, in the circuit topology of the inverter described above, 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.

[0248] And, understandably, Figures 3 to 6 Corresponding clamping circuits can also be added to the inverter k in the embodiment to achieve clamping protection of inverter k. The specific clamping circuit device settings can be found in the corresponding attached figure. This embodiment will not be described in detail here.

[0249] Please see below. Figure 13 Optionally, according to some embodiments of this application, the fractal connector module 30 includes N+1 three-phase dual-winding transformers;

[0250] In the N+1 three-phase double-winding transformers, the input terminals of the first to Nth three-phase double-winding transformers are electrically connected to the AC side of the N inverters one by one, the input terminal of the N+1th three-phase double-winding transformer is electrically connected to the AC side of the harmonic generation inverter 21, and the output terminals of the N+1 three-phase double-winding transformers are electrically connected to the AC output port through the AC busbar.

[0251] Alternatively, the fractal connector module 30 includes N three-phase dual-winding transformers and connecting components (not shown in the figure);

[0252] The input terminals of N three-phase double-winding transformers are electrically connected to the AC sides of N inverters one by one, and the output terminals of the N three-phase double-winding transformers are electrically connected to the AC output ports through the AC busbar; the AC side of the harmonic generation inverter 21 is electrically connected to the AC busbar through the connecting component.

[0253] In specific implementation, Figure 13 For example, after the switching frequency of the switching units within the N inverters decreases, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output to the corresponding three-phase dual-winding transformers, and then electrically connected to the AC output port via the AC busbar. The harmonic generation inverter 21 generates the corresponding second harmonic signal based on the first harmonic signal, which is output to the corresponding three-phase dual-winding transformer, and then electrically connected to the AC output port via the AC busbar.

[0254] 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0255] Alternatively, in other embodiments, the AC side of the harmonic generating inverter 21 is electrically connected to the AC collecting bus via a connecting component. This connecting component can be, for example, a wiring harness. Thus, by directly connecting the AC side of the harmonic generating inverter 21 to the AC collecting bus via the connecting component to form a parallel structure when matching voltage levels between the AC sides, transformer costs are saved.

[0256] Please see below. Figure 14 Optionally, according to some embodiments of this application, the fractal connector module 30 includes a three-phase multi-winding transformer;

[0257] The three-phase multi-winding transformer includes N+1 first windings 311 and 1 second winding 312, with the N+1 first windings 311 and the second winding 312 coupled together.

[0258] In the N+1 first windings 311, the first to Nth first windings 311 are electrically connected to the AC side of the N inverters one by one, the N+1th first winding 311 is electrically connected to the AC side of the harmonic generating inverter 21, and the second winding 312 is electrically connected to the AC output port.

[0259] Alternatively, the three-phase multi-winding transformer includes N first windings 311 and 1 second winding 312, with the N first windings 311 and the second winding 312 coupled together. The fractal connector module 30 also includes a connecting component (not shown in the figure).

[0260] The N first windings 311 are electrically connected to the AC sides of the N inverters one by one, the second winding 312 is electrically connected to the AC output port, and the AC side of the harmonic generating inverter 21 is electrically connected to the AC output port through the connecting component.

[0261] In specific implementation, Figure 14 For example, after the switching frequency of the switching units within the N inverters decreases, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output to the first N windings 311 of the corresponding three-phase multi-winding transformer, and then transmitted to the AC busbar through the second winding 312. The AC busbar is electrically connected to the AC output port. The harmonic generating inverter 21 generates the corresponding second harmonic signal based on the first harmonic signal, which is output to the (N+1)th winding 311 of the corresponding three-phase multi-winding transformer, and then transmitted to the AC busbar through the second winding 312. Finally, it is electrically connected to the AC output port through the AC busbar.

[0262] 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0263] Alternatively, in other embodiments, the AC side of the harmonic generating inverter 21 is electrically connected to the AC output port via a connecting component. This connecting component can be, for example, a wiring harness. Thus, when matching voltage levels between the AC sides, directly connecting the AC side of the harmonic generating inverter 21 to the AC output port via the connecting component forms a parallel structure, thereby saving transformer costs.

[0264] Please see below. Figure 15 Optionally, according to some embodiments of this application, the fractal connector module 30 includes: L three-phase multi-winding transformers, 1≤L≤N, where L is a positive integer, each of the L three-phase multi-winding transformers includes at least one first winding 311 and one second winding 312, and the first winding 311 and the second winding 312 in the same three-phase multi-winding transformer are coupled together.

[0265] The number of first windings 311 included in L three-phase multi-winding transformers is N. The N first windings 311 of the L three-phase multi-winding transformers are electrically connected to the AC side of N inverters one by one. The L second windings 312 of the L three-phase multi-winding transformers are electrically connected to the AC output port through the AC busbar.

[0266] The fractal connector module 30 also includes a three-phase dual-winding transformer or connection components (not shown in the figure);

[0267] The AC side of the harmonic generating inverter 21 is electrically connected to the AC collecting bus via a three-phase dual-winding transformer, or the AC side of the harmonic generating inverter 21 is electrically connected to the AC collecting bus via a connecting component, so as to be electrically connected to the AC output port via the AC collecting bus.

[0268] In practice, the windings of each of the L three-phase multi-winding transformers can be the same or different. For example, taking... Figure 15 For example, in the first three-phase multi-winding transformer, the input side includes M windings and the output side includes 1 winding. When M=2, it is a three-phase three-winding transformer. In other three-phase multi-winding transformers, the three-phase multi-winding transformer can also be, for example, a three-phase two-winding transformer, a three-phase four-winding transformer, etc., without strict limitation here, as long as the number of the first windings 311 included in L three-phase multi-winding transformers is N.

[0269] After the switching frequency of the switching units within the N inverters decreases, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output to the N first windings 311 of the L three-phase multi-winding transformers, and then transmitted to the AC busbar through the L second windings 312. The AC busbar is electrically connected to the AC output port. The harmonic generating inverter 21 generates the corresponding second harmonic signal based on the first harmonic signal, which is output to the corresponding three-phase dual-winding transformer, and then transmitted to the AC busbar through the three-phase dual-winding transformer. Finally, it is electrically connected to the AC output port through the AC busbar.

[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, 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0271] Alternatively, in other embodiments, the AC side of the harmonic generating inverter 21 is electrically connected to the AC output port via a connecting component. This connecting component can be, for example, a wiring harness. Thus, when matching voltage levels between the AC sides, the AC side of the harmonic generating inverter 21 is directly electrically connected to the AC busbar via the connecting component, and then electrically connected to the AC output port via the AC busbar to form a parallel structure, thereby saving transformer costs.

[0272] Please see below. Figure 16 Optionally, according to some embodiments of this application, the fractal connector module 30 includes a three-phase multi-winding transformer and a series transformer 320;

[0273] The three-phase multi-winding transformer includes N first windings 311 and 1 second winding 312, with the N first windings 311 and the second winding 312 coupled together.

[0274] N first windings 311 are electrically connected to the AC side of N inverters one by one, and the second windings 312 are electrically connected to the first input terminal of the series transformer 320.

[0275] The AC side of the harmonic generator inverter 21 is electrically connected to the second input terminal of the series transformer 320, and the output terminal of the series transformer 320 is electrically connected to the AC output port.

[0276] In specific implementation, Figure 16 For example, in this embodiment, the first input terminal of the series transformer 320 corresponds to port a, the second input terminal of the series transformer 320 corresponds to port b, and the output terminal of the series transformer 320 corresponds to port c.

[0277] Combination Figure 16 As shown, after the switching frequency of the switching units within the N inverters decreases, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output to the N first windings 311 of the corresponding three-phase multi-winding transformer, and then transmitted to the first input terminal of the series transformer 320 through the second winding 312. The output terminal of the series transformer 320 is electrically connected to the AC output port. The harmonic generating inverter 21 generates the corresponding second harmonic signal based on the first harmonic signal, which is output to the second input terminal of the series transformer 320 and then electrically connected to the AC output port through the output terminal of the series transformer 320.

[0278] 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0279] Please see below. Figure 17 Optionally, according to some embodiments of this application, the fractal connector module 30 includes N three-phase dual-winding transformers and series transformers 320;

[0280] The input terminals of N three-phase double-winding transformers are electrically connected to the AC side of N inverters one by one, and the output terminals of N three-phase double-winding transformers are electrically connected to the first input terminal of series transformer 320 through AC busbar.

[0281] The AC side of the harmonic generator inverter 21 is electrically connected to the second input terminal of the series transformer 320, and the output terminal of the series transformer 320 is electrically connected to the AC output port.

[0282] In specific implementation, Figure 17 For example, in this embodiment, the first input terminal of the series transformer 320 corresponds to port a, the second input terminal of the series transformer 320 corresponds to port b, and the output terminal of the series transformer 320 corresponds to port c.

[0283] Combination Figure 17 As shown, after the switching frequency of the switching units within the N inverters is reduced, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output to the corresponding three-phase dual-winding transformers, and then electrically connected to the first input terminal of the series transformer 320 through the AC busbar. Subsequently, they are electrically connected to the AC output port through the output terminal of the series transformer 320.

[0284] The harmonic generation inverter 21 generates a corresponding second harmonic signal based on the first harmonic signal, which is output to the corresponding three-phase dual-winding transformer. The second input terminal of the series transformer 320 is then connected through the three-phase dual-winding transformer. Finally, the output terminal of the series transformer 320 is electrically connected to the AC output port.

[0285] 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0286] Please see below. Figure 18Optionally, according to some embodiments of this application, the fractal connector module 30 includes: L three-phase multi-winding transformers and 1 series transformer 320, 1≤L≤N, where L is a positive integer. Each of the L three-phase multi-winding transformers includes at least one first winding 311 and one second winding 312. The first winding 311 and the second winding 312 in the same three-phase multi-winding transformer are coupled together.

[0287] The number of first windings 311 included in the L three-phase multi-winding transformers is N. The N first windings 311 of the L three-phase multi-winding transformers are electrically connected to the AC side of the N inverters one by one. The L second windings 312 of the L three-phase multi-winding transformers are electrically connected to the first input terminal of the series transformer 320 through the AC busbar.

[0288] The AC side of the harmonic generator inverter 21 is electrically connected to the second input terminal of the series transformer 320, and the output terminal of the series transformer 320 is electrically connected to the AC output port.

[0289] In specific implementation, Figure 18 For example, in this embodiment, the first input terminal of the series transformer 320 corresponds to port a, the second input terminal of the series transformer 320 corresponds to port b, and the output terminal of the series transformer 320 corresponds to port c.

[0290] Combination Figure 18 As shown, the windings of each of the L three-phase multi-winding transformers can be the same or different. For example, taking... Figure 15 For example, in the first three-phase multi-winding transformer, the input side includes M windings and the output side includes 1 winding. When M=2, it is a three-phase three-winding transformer. In other three-phase multi-winding transformers, the three-phase multi-winding transformer can also be, for example, a three-phase two-winding transformer, a three-phase four-winding transformer, etc., without strict limitation here, as long as the number of the first windings 311 included in L three-phase multi-winding transformers is N.

[0291] After the switching frequency of the switching units within the N inverters decreases, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output to the N first windings 311 of the L three-phase multi-winding transformers, and then transmitted to the first input terminal of the series transformer 320 through the L second windings 312. The output terminal of the series transformer 320 is then electrically connected to the AC output port. The harmonic generation inverter 21 generates a corresponding second harmonic signal based on the first harmonic signal, which is output to the corresponding three-phase dual-winding transformer. This signal is then transmitted to the second input terminal of the series transformer 320 through the three-phase dual-winding transformer, and finally electrically connected to the AC output port through the output terminal of the series transformer 320.

[0292] 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0293] Please see below. Figure 19 Optionally, according to some embodiments of this application, the series transformer 320 includes: a first transformer 321, a second transformer 322, and a third transformer 323;

[0294] The first terminal of the first transformer 321 is electrically connected to the first terminal of the first input terminal of the series transformer 320, the second terminal of the first transformer 321 is electrically connected to the first terminal of the AC output port, the third terminal of the first transformer 321 is electrically connected to the neutral point or ground terminal, and the fourth terminal of the first transformer 321 is electrically connected to the first terminal of the AC side of the harmonic generating inverter 21.

[0295] The first terminal of the second transformer 322 is electrically connected to the second terminal of the first input terminal of the series transformer 320, the second terminal of the second transformer 322 is electrically connected to the second terminal of the AC output port, the third terminal of the second transformer 322 is electrically connected to the neutral point or ground terminal, and the fourth terminal of the second transformer 322 is electrically connected to the second terminal of the AC side of the harmonic generation inverter 21.

[0296] The first terminal of the third transformer 323 is electrically connected to the third terminal of the first input terminal of the series transformer 320. The second terminal of the third transformer 323 is electrically connected to the third terminal of the AC output port. The third terminal of the third transformer 323 is electrically connected to the neutral point or ground terminal. The fourth terminal of the third transformer 323 is electrically connected to the third terminal of the AC side of the harmonic generation inverter 21.

[0297] In specific implementation, Figure 19 For example, in this embodiment, the first input terminal of the series transformer 320 corresponds to port a, and the specific connection of port a can be, for example, combined with Figures 16 to 18 As shown. The second input terminal of the series transformer 320 corresponds to port b, which is used for electrical connection with the AC side of the harmonic generation inverter 21. The output terminal of the series transformer 320 corresponds to port c, which is used for electrical connection with the AC port.

[0298] like Figure 19As shown, the first transformer 321, the second transformer 322, and the third transformer 323 are single-phase, dual-winding transformers. One winding of the first transformer 321 is connected to the A-phase terminal of the AC output port and the A-phase terminal of the output side of the N inverters after passing through the transformer, 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 achieves series connection of the output side of the N inverters after passing through the transformer and the AC A-phase of the harmonic generator inverter 21, and connects it to the A-phase of the AC output port. The second transformer 322 and the third transformer 323 are used for series connection of the N inverters and the B-phase and C-phase of the harmonic generator inverter 21, respectively, and are connected to the B-phase and C-phase of the AC output port.

[0299] In practice, after the switching frequency of the switching units within the N inverters is reduced, the N inverters generate the first harmonic signal within the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters 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 the different output terminals of the N inverters are then output after passing through transformers. The signals output from the output side of the N inverters after passing through the transformers and the harmonic signals output from the AC side of the harmonic generation inverter 21 are all output to the first transformer 321, the second transformer 322, and the third transformer 323.

[0300] 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 high-voltage fractal converter 100 and increases the output capacity of the high-voltage fractal converter 100.

[0301] Please see below. Figure 20 Optionally, according to some embodiments of this application, the series transformer 320 includes: a first single-phase winding 324, a second single-phase winding 325, a third single-phase winding 326, and a third winding 327.

[0302] The first single-phase winding 324, the second single-phase winding 325, and the third single-phase winding 326 are electrically coupled to the third winding 327.

[0303] The first end of the first single-phase winding 324 is electrically connected to the first end of the first input terminal of the series transformer 320, and the second end of the first single-phase winding 324 is electrically connected to the first end of the AC output port.

[0304] The first end of the second single-phase winding 325 is electrically connected to the second end of the first input terminal of the series transformer 320, and the second end of the second single-phase winding 325 is electrically connected to the second end of the AC output port.

[0305] The first end of the third single-phase winding 326 is electrically connected to the third end of the first input terminal of the series transformer 320, and the second end of the third single-phase winding 326 is electrically connected to the third end of the AC output port.

[0306] The third winding 327 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.

[0307] In specific implementation, Figure 20 For example, in this embodiment, the first input terminal of the series transformer 320 corresponds to port a, and the specific connection of port a can be, for example, combined with Figures 16 to 18 As shown. The second input terminal of the series transformer 320 corresponds to port b, which is used for electrical connection with the AC side of the harmonic generation inverter 21. The output terminal of the series transformer 320 corresponds to port c, which is used for electrical connection with the AC port.

[0308] like Figure 20 As shown, when the series transformer 320 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 generation 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.

[0309] In practice, the third winding 327 can be either a star-connected winding or a delta-connected winding. After the switching frequency of the switching units in the N inverters is reduced, the N inverters generate the first harmonic signal in the higher harmonic range. The fundamental signal and the first harmonic signal generated by the N inverters are output from different output terminals. The second harmonic signal generated by the harmonic generating 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 N inverters are all output to the first single-phase winding 324, the second single-phase winding 325, and the third single-phase winding 326 after passing through the transformer. The harmonic signals output from different output terminals of the harmonic generating inverter 21 are all output into the third winding 327.

[0310] 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 high-voltage fractal converter 100 and increasing the output capacity of the high-voltage fractal converter 100.

[0311] It should be added here that the above Figures 13 to 20 The winding connection methods shown are for illustrative purposes only. In practical applications, the windings can be, for example, delta-connected windings or star-connected windings. The above figures are not intended to limit the scope of protection of this application.

[0312] It is important to note that the above... Figures 13 to 20 The fractal connector module 30 shown mainly includes two types: parallel fractal connector modules and series fractal connector modules. By reasonably setting the transformer phase in the fractal connector module 30, the AC voltage of each inverter in the inverter module 10 can be multiplexed, reducing AC voltage harmonics, optimizing waveform quality, reducing the voltage conversion rate of the AC port, and further reducing the capacity of the harmonic generation module 20.

[0313] Please see below. Figure 21 Optionally, according to some embodiments of this application, the high-voltage fractal converter 100 further includes:

[0314] The first filter has its first end electrically connected to the AC side of the kth inverter among the N inverters, and its second end electrically connected to the corresponding first input end in the fractal connector module 30, where 1≤k≤N and k is a positive integer.

[0315] And / or, a second filter, the first end of which is electrically connected to the AC side of the corresponding harmonic generating inverter 21, and the second end of which is electrically connected to the second input end in the fractal connector module 30.

[0316] For example, the first filter and / or the second filter 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.

[0317] The first filter is, for example Figure 21 The first filter can be any one of filters 1 to N in the configuration. The first filter can be used to filter out interference signals in the AC output of the corresponding inverter k, 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 can be flexibly configured according to actual needs.

[0318] The second filter is, for example Figure 21 The filter N+1 is used 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 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.

[0319] 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.

[0320] For example, such as Figure 22 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.

[0321] 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 series and parallel connection methods and specific structures of the semiconductor power switch units can be found in the preceding text. Figures 4-9 The structure example shown.

[0322] 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 seventh 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.

[0323] 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 eighth 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.

[0324] The first terminal of the fifth semiconductor switch 215 is connected to the positive terminal of the second DC power supply port, the second terminal of the fifth semiconductor switch 215 is connected to the first terminal of the sixth semiconductor switch 216 at the midpoint F of the ninth bridge arm, and the second terminal of the sixth semiconductor switch 216 is connected to the negative terminal of the second DC power supply port.

[0325] The midpoints D of the seventh bridge arm, E of the eighth bridge arm, and F of the ninth bridge arm are all connected to the fractal connector module 30.

[0326] In specific implementation, the first harmonic signal generated by the high-voltage 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 they output a second harmonic signal with the opposite waveform to the first harmonic signal, and output it to the fractal connector module 30.

[0327] 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 output power capability of the high-voltage fractal converter 100. While reducing the switching frequency of N inverters, the output capacity of the converter can also be increased.

[0328] It is understood that the above are all examples and do not serve as a substantial limitation on the high-voltage fractal converter 100 protected in this application.

[0329] It should be added that the high-voltage fractal converter 100 provided in this application can realize decoupled control of AC and DC voltage and bidirectional power transmission, and can be used as an inverter or a rectifier.

[0330] 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.

[0331] 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.

[0332] 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.

[0333] 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.

[0334] 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 high-voltage fractal converter, characterized in that, The high-voltage fractal converter includes: An inverter module includes N inverters, where N > 1 and N is a positive integer. The DC side of each of the N inverters is electrically connected to one of the N first DC power supply ports. The N first DC power supply ports are connected in series. The N inverters are used to output AC signals, which include first harmonic signals in the higher harmonic range. The harmonic generation module includes a harmonic generation inverter, wherein the DC side of the harmonic generation inverter is electrically connected to a second DC power supply port, and the harmonic generation inverter is used to output a corresponding second harmonic signal according to the first harmonic signal; The fractal connector module has N first input terminals that are electrically connected to the AC side of the N inverters one by one, a second input terminal that is electrically connected to the AC side of the harmonic generating inverter, and an output terminal that is electrically connected to the AC output port. The second harmonic signal is used to compensate for the first harmonic signal within the fractal connector module.

2. The high-voltage 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 high-voltage fractal converter according to claim 1, characterized in that, The k-th inverter among the N inverters includes: at least one supporting capacitor and a three-phase inverter bridge, 1≤k≤N, where k is a positive integer; The at least one supporting capacitor is connected in series between the kth first DC power supply ports; The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, and a sixth switching unit; The first terminal of the first switching unit, the first terminal of the third switching unit, and the first terminal of the fifth switching unit are electrically connected to the positive terminal of the k-th first DC power supply port; The second end of the first switch unit and the first end of the second switch unit are electrically connected to the midpoint of the first bridge arm; the second end of the third switch unit and the first end of the fourth switch unit are electrically connected to the midpoint of the second bridge arm; and the second end of the fifth switch unit and the first end of the sixth switch unit are electrically connected to the midpoint of the third bridge arm. The second terminal of the second switching unit, the second terminal of the fourth switching unit, and the second terminal of the sixth switching unit are electrically connected to the negative terminal of the kth first DC power supply port; The midpoints of the first bridge arm, the second bridge arm, and the third bridge arm are electrically connected to the AC side of the k-th inverter.

4. The high-voltage fractal converter according to claim 1, characterized in that, The k-th inverter among the N inverters includes: a first supporting capacitor, a second supporting capacitor, and a three-phase inverter bridge, where 1≤k≤N and k is a positive integer; The first end of the first supporting capacitor is electrically connected to the positive terminal of the kth first DC power supply port, the second end of the first supporting capacitor and the first end of the second supporting capacitor are electrically connected to the neutral point, and the second end of the second supporting capacitor is electrically connected to the negative terminal of the kth first DC power supply port. The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, a twelfth switching unit, a thirteenth switching unit, a fourteenth switching unit, a fifteenth switching unit, a sixteenth switching unit, a seventeenth switching unit, and an eighteenth switching unit; The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are sequentially connected in series between the k-th first DC power supply port. The first switch unit and the second switch unit are electrically connected to the first node, the second switch unit and the third switch unit are electrically connected to the midpoint of the first bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node. The first end of the fifth switch unit is electrically connected to the first node, the second end of the fifth switch unit and the first end of the sixth switch unit are electrically connected to the neutral point, and the second end of the sixth switch unit is electrically connected to the second node. The seventh, eighth, ninth, and tenth switch units are sequentially connected in series between the k-th first DC power supply port. The seventh and eighth switch units are electrically connected to the third node, the eighth and ninth switch units are electrically connected to the midpoint of the second bridge arm, and the ninth and tenth switch units are electrically connected to the fourth node. The first end of the eleventh switch unit is electrically connected to the third node, the second end of the eleventh switch unit and the first end of the twelfth switch unit are electrically connected to the neutral point, and the second end of the twelfth switch unit is electrically connected to the fourth node. The thirteenth, fourteenth, fifteenth, and sixteenth switch units are sequentially connected in series between the kth first DC power supply port. The thirteenth and fourteenth switch units are electrically connected to the fifth node, the fourteenth and fifteenth switch units are electrically connected to the midpoint of the third bridge arm, and the fifteenth and sixteenth switch units are electrically connected to the sixth node. The first end of the seventeenth switch unit is electrically connected to the fifth node, the second end of the seventeenth switch unit and the first end of the eighteenth switch unit are electrically connected to the neutral point, and the second end of the eighteenth switch unit is electrically connected to the sixth node. The midpoints of the first bridge arm, the second bridge arm, and the third bridge arm are electrically connected to the AC side of the k-th inverter.

5. The high-voltage fractal converter according to claim 1, characterized in that, The k-th inverter among the N inverters includes: a first supporting capacitor, a second supporting capacitor, and a three-phase inverter bridge, where 1≤k≤N and k is a positive integer; The first end of the first supporting capacitor is electrically connected to the positive terminal of the kth first DC power supply port, the second end of the first supporting capacitor and the first end of the second supporting capacitor are electrically connected to the neutral point, and the second end of the second supporting capacitor is electrically connected to the negative terminal of the kth first DC power supply port. The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit, as well as a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode; The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are sequentially connected in series between the k-th first DC power supply port. The first switch unit and the second switch unit are electrically connected to the first node, the second switch unit and the third switch unit are electrically connected to the midpoint of the first bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node. The cathode of the first diode is electrically connected to the first node, the anode of the first diode and the cathode of the second diode are electrically connected to the neutral point, and the anode of the second diode is electrically connected to the second node. The fifth, sixth, seventh, and eighth switch units are sequentially connected in series between the k-th first DC power supply port. The fifth and sixth switch units are electrically connected to the third node, the sixth and seventh switch units are electrically connected to the midpoint of the second bridge arm, and the seventh and eighth switch units are electrically connected to the fourth node. The cathode of the third diode is electrically connected to the third node, the anode of the third diode and the cathode of the fourth diode are electrically connected to the neutral point, and the anode of the fourth diode is electrically connected to the fourth node. The ninth, tenth, eleventh, and twelfth switch units are sequentially connected in series between the kth first DC power supply port. The ninth and tenth switch units are electrically connected to the fifth node, the tenth and eleventh switch units are electrically connected to the midpoint of the third bridge arm, and the eleventh and twelfth switch units are electrically connected to the sixth node. The cathode of the first diode is electrically connected to the fifth node, the anode of the first diode and the cathode of the second diode are electrically connected to the neutral point, and the anode of the second diode is electrically connected to the sixth node. The midpoints of the first bridge arm, the second bridge arm, and the third bridge arm are electrically connected to the AC side of the k-th inverter.

6. The high-voltage fractal converter according to claim 1, characterized in that, The k-th inverter among the N inverters includes: a first supporting capacitor, a second supporting capacitor, and a three-phase inverter bridge, where 1≤k≤N and k is a positive integer; The first end of the first supporting capacitor is electrically connected to the positive terminal of the kth first DC power supply port, the second end of the first supporting capacitor and the first end of the second supporting capacitor are electrically connected to the neutral point, and the second end of the second supporting capacitor is electrically connected to the negative terminal of the kth first DC power supply port. The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit; The first end of the first switch unit, the first end of the fifth switch unit, and the first end of the ninth switch unit are electrically connected to the positive terminal of the kth first DC power supply port. The second end of the first switch unit and the first end of the fourth switch unit are electrically connected to the midpoint of the first bridge arm. The second end of the fifth switch unit and the first end of the eighth switch unit are electrically connected to the midpoint of the second bridge arm. The second end of the ninth switch unit and the first end of the twelfth switch unit are electrically connected to the midpoint of the third bridge arm. The first terminal of the second switching unit is electrically connected to the neutral point, the second terminal of the second switching unit is electrically connected to the second terminal of the third switching unit, and the first terminal of the third switching unit is electrically connected to the midpoint of the first bridge arm; the first terminal of the sixth switching unit is electrically connected to the neutral point, the second terminal of the sixth switching unit is electrically connected to the second terminal of the seventh switching unit, and the first terminal of the seventh switching unit is electrically connected to the midpoint of the second bridge arm; the first terminal of the tenth switching unit is electrically connected to the neutral point, the second terminal of the tenth switching unit is electrically connected to the second terminal of the eleventh switching unit, and the first terminal of the eleventh switching unit is electrically connected to the midpoint of the third bridge arm; The midpoints of the first bridge arm, the second bridge arm, and the third bridge arm are electrically connected to the AC side of the k-th inverter.

7. The high-voltage fractal converter according to claim 1, characterized in that, The k-th inverter among the N inverters includes: at least one supporting capacitor and a three-phase inverter bridge, 1≤k≤N, where k is a positive integer; The at least one supporting capacitor is connected in series between the kth first DC power supply ports; The three-phase inverter bridge includes: a first switching unit, a second switching unit, a third switching unit, a fourth switching unit, a fifth switching unit, a sixth switching unit, a seventh switching unit, an eighth switching unit, a ninth switching unit, a tenth switching unit, an eleventh switching unit, and a twelfth switching unit, as well as a first capacitor, a second capacitor, and a third capacitor; The first switch unit, the second switch unit, the third switch unit, and the fourth switch unit are sequentially connected in series between the k-th first DC power supply port. The first switch unit and the second switch unit are electrically connected to the first node, the second switch unit and the third switch unit are electrically connected to the midpoint of the first bridge arm, and the third switch unit and the fourth switch unit are electrically connected to the second node. The first capacitor is electrically connected between the first node and the second node. The fifth, sixth, seventh, and eighth switch units are sequentially connected in series between the k-th first DC power supply port. The fifth and sixth switch units are electrically connected to the third node, the sixth and seventh switch units are electrically connected to the midpoint of the second bridge arm, and the seventh and eighth switch units are electrically connected to the fourth node. The second capacitor is electrically connected between the third and fourth nodes. The ninth, tenth, eleventh, and twelfth switch units are sequentially connected in series between the kth first DC power supply port. The ninth and tenth switch units are electrically connected to the fifth node, the tenth and eleventh switch units are electrically connected to the midpoint of the third bridge arm, and the eleventh and twelfth switch units are electrically connected to the sixth node. The third capacitor is electrically connected between the fifth and sixth nodes. The midpoints of the first bridge arm, the second bridge arm, and the third bridge arm are electrically connected to the AC side of the k-th inverter.

8. The high-voltage fractal converter according to any one of claims 3-7, characterized in that, The N inverters include 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.

9. The high-voltage fractal converter according to claim 8, characterized in that, The semiconductor switching unit in any of the switching units of the k-th inverter among the N inverters includes an IGCT; The k-th inverter further includes a clamping circuit disposed between the k-th first DC power supply ports.

10. The high-voltage fractal converter according to any one of claims 1-7, characterized in that, The fractal connector module includes N+1 three-phase dual-winding transformers; In the N+1 three-phase dual-winding transformers, the input terminals of the first to Nth three-phase dual-winding transformers are electrically connected to the AC side of the N inverters one by one, the input terminal of the N+1th three-phase dual-winding transformer is electrically connected to the AC side of the harmonic generation inverter, and the output terminals of the N+1 three-phase dual-winding transformers are electrically connected to the AC output port through the AC busbar. Alternatively, the fractal connector module may include N three-phase dual-winding transformers and connecting components; The input terminals of the N three-phase double-winding transformers are electrically connected to the AC sides of the N inverters one by one, and the output terminals of the N three-phase double-winding transformers are electrically connected to the AC output port through the AC busbar; the AC side of the harmonic generating inverter is electrically connected to the AC busbar through the connecting component.

11. The high-voltage fractal converter according to any one of claims 1-7, characterized in that, The fractal connector module includes a three-phase multi-winding transformer; The three-phase multi-winding transformer includes N+1 first windings and 1 second winding, wherein the N+1 first windings and the second winding are coupled together. Of the N+1 first windings, the first to Nth first windings are electrically connected to the AC side of the N inverters one by one, the N+1th first winding is electrically connected to the AC side of the harmonic generating inverter, and the second winding is electrically connected to the AC output port. Alternatively, the three-phase multi-winding transformer includes N first windings and 1 second winding, wherein the N first windings and the second winding are coupled together, and the fractal connector module further includes a connecting component; The N first windings are electrically connected to the AC sides of the N inverters one by one, the second windings are electrically connected to the AC output ports, and the AC side of the harmonic generating inverter is electrically connected to the AC output ports through the connecting components.

12. The high-voltage fractal converter according to any one of claims 1-7, characterized in that, The fractal connector module includes: L three-phase multi-winding transformers, 1≤L≤N, where L is a positive integer. Each of the L three-phase multi-winding transformers includes at least one first winding and one second winding. The first winding and the second winding in the same three-phase multi-winding transformer are coupled together. The L three-phase multi-winding transformers include N first windings. The N first windings of the L three-phase multi-winding transformers are electrically connected to the AC side of the N inverters one by one. The L second windings of the L three-phase multi-winding transformers are electrically connected to the AC output port through the AC busbar. The fractal connector module also includes a three-phase dual-winding transformer or connecting components; The AC side of the harmonic generating inverter is electrically connected to the AC collecting bus via the three-phase dual-winding transformer, or the AC side of the harmonic generating inverter is electrically connected to the AC collecting bus via the connecting component, so as to be electrically connected to the AC output port via the AC collecting bus.

13. The high-voltage fractal converter according to claim 1, characterized in that, The fractal connector module includes a three-phase multi-winding transformer and a series transformer; The three-phase multi-winding transformer includes N first windings and 1 second winding, wherein the N first windings and the second winding are coupled together. The N first windings are electrically connected to the AC side of the N inverters one by one, and the second windings are electrically connected to the first input terminal of the series transformer. The AC side of the harmonic generator inverter is electrically connected to the second input terminal of the series transformer, and the output terminal of the series transformer is electrically connected to the AC output port.

14. The high-voltage fractal converter according to claim 1, characterized in that, The fractal connector module includes N three-phase dual-winding transformers and series transformers; The input terminals of the N three-phase double-winding transformers are electrically connected one-to-one with the AC side of the N inverters, and the output terminals of the N three-phase double-winding transformers are electrically connected to the first input terminal of the series transformer through the AC busbar. The AC side of the harmonic generator inverter is electrically connected to the second input terminal of the series transformer, and the output terminal of the series transformer is electrically connected to the AC output port.

15. The high-voltage fractal converter according to claim 1, characterized in that, The fractal connector module includes: L three-phase multi-winding transformers and 1 series transformer, 1≤L≤N, where L is a positive integer. Each of the L three-phase multi-winding transformers includes at least one first winding and one second winding. The first winding and the second winding in the same three-phase multi-winding transformer are coupled together. The L three-phase multi-winding transformers include N first windings. The N first windings of the L three-phase multi-winding transformers are electrically connected to the AC side of the N inverters one by one. The L second windings of the L three-phase multi-winding transformers are electrically connected to the first input terminal of the series transformer through the AC busbar. The AC side of the harmonic generator inverter is electrically connected to the second input terminal of the series transformer, and the output terminal of the series transformer is electrically connected to the AC output port.

16. The high-voltage fractal converter according to any one of claims 13-15, 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 first input terminal of the series transformer, 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 generating inverter. The first terminal of the second transformer is electrically connected to the second terminal of the first input terminal of the series transformer, 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 generating inverter. The first terminal of the third transformer is electrically connected to the third terminal of the first input terminal of the series transformer, 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 generating inverter.

17. The high-voltage fractal converter according to any one of claims 13-15, characterized in that, The series transformer includes: a first single-phase winding, a second single-phase winding, a third single-phase winding, and a third winding; The first single-phase winding, the second single-phase winding, and the third single-phase winding are coupled and electrically connected to the third winding; The first end of the first single-phase winding is electrically connected to the first end of the first input terminal of the series transformer, 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 first input terminal of the series transformer, 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 first input terminal of the series transformer, and the second end of the third single-phase winding is electrically connected to the third end of the AC output port. The third 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.

18. The high-voltage fractal converter according to any one of claims 1-7, characterized in that, The high-voltage fractal converter also includes: The first filter has a first end electrically connected to the AC side of the kth inverter among the N inverters, and a second end electrically connected to the corresponding first input end in the fractal connector module, where 1≤k≤N and k is a positive integer; 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 second input terminal in the fractal connector module.

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