Isolated matrix converter system and its control method

Abstract

This application provides an isolated matrix converter system and its control method. The isolated matrix converter system includes: a first output port; a second output port; at least one converter valve bridge arm; and at least one multi-winding transformer. The multi-winding transformer includes: a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the converter valve bridge arm; the first secondary winding is connected to the first output port; and the second secondary winding is connected to the second output port. This application optimizes the configuration of magnetic components in the matrix converter system, rationally configures the bridge arm combination, and optimizes the operating state of the magnetic components. While reducing the magnetic saturation of magnetic devices such as bridge arm reactance or transformers, it integrates the transformers on both sides of the matrix converter system, reducing the system's footprint.

Description

Technical Field

[0001] This application relates to the field of power electronics application technology, and more specifically, to an isolated matrix converter system and its control method. Background Technology

[0002] In low-frequency power transmission systems, AC-AC converters are used for power frequency and low-frequency voltage conversion. In high-voltage applications, the most common and mature AC-AC converter is the modular multilevel matrix converter (M3C). However, this converter requires nine links, resulting in a large number of modules and high system cost. Therefore, a method is adopted to reduce the voltage level on the converter valve side by adding isolation transformers. This reduces the number of modules and lowers system cost while ensuring the current stress on the switching devices. However, the system still requires magnetic components such as reactors and isolation transformers, resulting in a still large system footprint.

[0003] Patent CN113381620A proposes a circuit that combines a transformer and a reactor, eliminating the need for an external isolation transformer. However, in this scheme, the three primary windings of the transformer use mixed-frequency current, while the secondary winding uses low-frequency current, leading to excessive excitation current in the actual transformer core.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] This application aims to provide an isolated matrix converter system and its control method, which can fully consider magnetic coupling and magnetic balance characteristics, reduce the design requirements of magnetic components, and reduce the overall system cost and footprint.

[0006] According to one aspect of this application, an isolated matrix converter system is proposed, comprising:

[0007] First output port;

[0008] Second output port;

[0009] At least one converter valve bridge arm,

[0010] At least one multi-winding transformer, the multi-winding transformer comprising: a primary winding, a first secondary winding, and a second secondary winding;

[0011] The primary winding is connected to the converter valve bridge arm; the first secondary winding is connected to the first output port; and the second secondary winding is connected to the second output port.

[0012] According to some embodiments, it also includes:

[0013] The bridge arm reactor is connected in series with the converter valve bridge arm.

[0014] According to some embodiments, it also includes:

[0015] A first frequency AC system is connected to the first output port in phase sequence; and

[0016] The second frequency AC system is connected to the second output port in phase order.

[0017] According to some embodiments, it also includes a first buffer reactance and a second buffer reactance, wherein,

[0018] The first output port of the matrix converter system is connected to the first buffer reactor in phase order, and then connected to the first frequency AC system.

[0019] The second output port of the matrix converter system is connected to the second buffer reactor in phase order, and then connected to the second frequency AC system.

[0020] According to some embodiments, it also includes a first soft-start branch and a second soft-start branch, wherein,

[0021] The first output port of the isolated matrix converter system is connected to the first soft-start branch and then to the first frequency AC system.

[0022] The second output port of the isolated matrix converter system is connected to the second soft-start branch and then to the second frequency AC system.

[0023] According to some embodiments, one of the first soft-start branch and the second soft-start branch includes a charging switch, a charging resistor, and a bypass switch, while the other soft-start branch includes an isolating switch; or

[0024] Both the first soft-start branch and the second soft-start branch include the charging switch, the charging resistor, and the bypass switch;

[0025] Wherein, the charging switch is connected in series with the charging resistor, and the bypass switch is connected in parallel with the charging resistor; or

[0026] The bypass switch is connected in parallel with the branch of the charging switch and the charging resistor that are connected in series.

[0027] According to some embodiments, the primary winding connection to the converter valve bridge arm includes:

[0028] The primary winding of the multi-winding transformer consists of only one winding, and the converter valve bridge arm is connected to both ends of the primary winding; or

[0029] The primary winding of the multi-winding transformer includes multiple windings, which are connected in a star or delta configuration depending on the phase.

[0030] The number of phases of the converter valve bridge arm is the same as that of the primary winding. One end of the converter valve bridge arm is short-circuited, and the other end is connected to one phase of the primary winding; or

[0031] The converter valve bridge arm and the primary winding form a series branch, which is connected end to end with the other series branches.

[0032] According to some embodiments, the first secondary winding is connected to the first output port, and the second secondary winding is connected to the second output port, including:

[0033] The first secondary winding / second secondary winding of the multi-winding transformer includes only one winding, and the two ends of the first secondary winding / second secondary winding are connected between the two phases of the first output port / second output port; or

[0034] The isolated matrix converter system includes multiple multi-winding transformers, and the first secondary winding / second secondary winding of each multi-winding transformer includes only one winding. The first secondary winding / second secondary windings of the multiple multi-winding transformers are connected in a star or delta configuration according to the phase configuration, and then connected to the first output port / second output port; or

[0035] The first secondary winding / second secondary winding of the multi-winding transformer includes multiple windings, which are connected in a star or delta configuration according to the phase configuration, and then connected to the corresponding phases of the first output port / second output port.

[0036] According to some embodiments, including:

[0037] The primary winding, first secondary winding, or second secondary winding of the multi-winding transformer adopts the star connection method, and the grounding method includes: direct grounding, grounding through the target coil, grounding through the target resistor, or no grounding; or

[0038] The grounding method adopts a delta connection method, which includes: grounding through a Z-type transformer, grounding through three reactors, or no grounding.

[0039] According to some embodiments, the converter valve bridge arm includes N sub-modules connected in series, where N is a positive integer greater than or equal to 1;

[0040] The submodule includes a full-bridge circuit, and each submodule is connected in series through an AC port.

[0041] According to another aspect of this application, a control method for an isolated matrix converter system is proposed. The isolated matrix converter system includes a first soft-start branch and a second soft-start branch. One of the first and second soft-start branches includes a charging switch, a charging resistor, and a bypass switch, while the other soft-start branch includes an isolating switch; or both the first and second soft-start branches include the charging switch, the charging resistor, and the bypass switch. The system also includes a first frequency AC system, a second frequency AC system, a first output port, a second output port, at least one converter valve bridge arm, and at least one multi-winding transformer. The multi-winding transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the converter valve bridge arm, the first secondary winding is connected to the first output port, and the second secondary winding is connected to the second output port. The control method for the isolated matrix converter system includes:

[0042] Start from the first frequency AC system or start from the second frequency AC system.

[0043] According to some embodiments, the initiation from the first frequency AC system includes:

[0044] If the first soft starter branch or the second soft starter branch includes a disconnect switch, then the disconnect switch is closed;

[0045] Close the charging switch of the first soft starter branch;

[0046] In response to the completion of charging of the converter valve bridge arm, the bypass switch of the first soft start branch is closed;

[0047] Unlock the converter valve bridge arm;

[0048] Close the charging switch of the second soft starter branch and close the bypass switch of the second soft starter branch.

[0049] According to some embodiments, the startup from the second frequency AC system includes:

[0050] If the second soft starter branch or the first soft starter branch includes an isolating switch, then the isolating switch is closed;

[0051] Close the charging switch of the second soft start branch;

[0052] In response to the completion of charging of the converter valve bridge arm, the bypass switch of the second soft start branch is closed;

[0053] Unlock the converter valve bridge arm;

[0054] Close the charging switch of the first soft starter branch and close the bypass switch of the first soft starter branch.

[0055] This application provides an isolated matrix converter system and its control method. By analyzing the operating current characteristics of the matrix converter, appropriate converter valve arms are selected and grouped. After grouping, the mixing current in the converter valve arms can achieve three-phase balance in two frequency dimensions. Furthermore, a three-winding transformer can be constructed using the three-phase balanced current. After certain phase connections, the mixing current of the transformer is short-circuited in two frequency dimensions to output the frequency after frequency conversion. For the three windings of the transformer, although the operating current is the mixing frequency, magnetic balance can be achieved on both sides due to the current balance design. Therefore, the design requirements of the three-winding transformer can be reduced, and the isolation function of the two sides of the frequency conversion valve and the valve can be completed. It can also indirectly reduce its cost and footprint.

[0056] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0057] The above and other objects, features, and advantages of this application will become more apparent from the detailed description of exemplary embodiments with reference to the accompanying drawings. The drawings described below are merely some embodiments of this application and are not intended to limit the scope of this application.

[0058] Figure 1 A connection diagram of a matrix converter system in an exemplary embodiment is shown;

[0059] Figure 2 A schematic diagram of an exemplary three-phase isolation transformer in which the primary winding, the first secondary winding, and the second secondary winding are all star-connected is shown.

[0060] Figure 3 This diagram illustrates an exemplary three-phase isolation transformer with a primary winding delta connection and a first secondary winding and a second secondary winding star connection.

[0061] Figure 4 A schematic diagram of an exemplary three-winding transformer is shown;

[0062] Figure 5 A schematic diagram of an exemplary buffer reactance is shown;

[0063] Figure 6 A schematic diagram of a soft-start branch of an exemplary embodiment is shown;

[0064] Figure 7 Another embodiment of an exemplary soft-start branch is shown in the diagram;

[0065] Figure 8 A schematic diagram of a full-bridge circuit of an exemplary embodiment is shown;

[0066] Figure 9 A schematic diagram of an isolated matrix converter system of an exemplary embodiment is shown;

[0067] Figure 10 Another embodiment of an exemplary isolated matrix converter system is shown;

[0068] Figure 11 Another embodiment of an exemplary isolated matrix converter system is shown;

[0069] Figure 12 Another embodiment of an exemplary isolated matrix converter system is shown;

[0070] Figure 13 A flowchart illustrating a control method for an isolated matrix converter system, as shown in an exemplary embodiment, is provided.

[0071] Figure 14 Another embodiment of a control method flowchart for an exemplary isolated matrix converter system is shown. Detailed Implementation

[0072] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0073] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0074] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0075] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0076] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of exemplary embodiments, and the modules or processes in the drawings are not necessarily essential for implementing this application, and therefore cannot be used to limit the scope of protection of this application.

[0077] This application proposes an isolated matrix converter system, comprising: a first output port; a second output port; at least one converter valve bridge arm; and at least one multi-winding transformer, the multi-winding transformer comprising: a primary winding, a first secondary winding, and a second secondary winding, the primary winding being connected to the converter valve bridge arm; the first secondary winding being connected to the first output port; and the second secondary winding being connected to the second output port.

[0078] Figure 1 A schematic diagram of the connection of a matrix converter system according to an exemplary embodiment is shown.

[0079] like Figure 1 As shown, component 1001 represents the first output port of the isolated matrix converter system, with phases A, B, and C shown in the figure; component 1002 represents the second output port of the isolated matrix converter system, with phases a, b, and c shown in the figure; components 1031, 1032, and 1033 represent multi-winding transformers; and component 104 represents the converter valve bridge arm.

[0080] The converter valve bridge arm 104 includes N sub-modules connected in series, where N is a positive integer greater than or equal to 1; the N sub-modules connected in series are constructed using a full-bridge circuit and connected in series through AC ports.

[0081] According to the example embodiment, Figure 2 , Figure 3 and Figure 4 This is a schematic diagram of a multi-winding transformer, in which components 203, 303 and 403 represent the primary winding, components 201, 301 and 401 represent the first secondary winding, and components 202, 302 and 402 represent the second secondary winding.

[0082] According to some embodiments, when the primary winding, the first secondary winding, and the second secondary winding of a multi-winding transformer are connected in a star configuration, the grounding method is determined according to system requirements; the grounding methods include: direct grounding, grounding through the target coil, grounding through the target resistor, and no grounding.

[0083] When the primary winding, first secondary winding, and second secondary winding of a multi-winding transformer are connected in a delta configuration, the grounding method is determined according to system requirements. Grounding methods include: grounding through a Z-type transformer, grounding through three reactors, and no grounding.

[0084] like Figure 2 As shown, component 204 represents the primary winding, the first secondary winding, and the second secondary winding of a multi-winding transformer. When a star connection is used, a direct grounding method is adopted.

[0085] like Figure 3 As shown, component 304 represents the primary winding, the first secondary winding, and the second secondary winding of a multi-winding transformer. When the delta connection is adopted, the grounding method through the Z-type transformer includes a Z-type transformer, three-phase reactor, a surge arrester, and a grounding resistor.

[0086] The embodiment uses three phases as an example, but this application is not limited to this.

[0087] According to some embodiments, the isolated matrix converter system also includes a bridge arm reactor 105, one end of which is connected in series with the converter valve bridge arm 104 of the isolated matrix converter system, and the other end of which is connected in series with a multi-winding transformer. For example... Figure 1 As shown, components 1041 to 104N represent N sub-modules connected in series.

[0088] According to some embodiments, the isolated matrix converter system further includes: a first buffer reactor and / or a second buffer reactor. For example... Figure 1 As shown, component 108 represents the first buffer reactance, and component 109 represents the second buffer reactance; Figure 5 This is a schematic diagram of the buffer reactance.

[0089] According to some embodiments, the first output port 1001 of the isolated matrix converter system is connected to the first buffer reactor 108 in phase order, and then connected to the first frequency AC system 101; the second output port 1002 of the isolated matrix converter system is connected to the second buffer reactor 109 in phase order, and then connected to the second frequency AC system 102.

[0090] According to some embodiments, the isolated matrix converter system further includes a first soft-start branch and a second soft-start branch; such as Figure 1As shown, component 106 represents the first soft start branch, and component 107 represents the second soft start branch.

[0091] The first output port 1001 of the isolated matrix converter system is connected to the first soft-start branch 106 and / or the first buffer reactor 108, and then connected to the first frequency AC system 101; the second output port 1002 of the isolated matrix converter system is connected to the second soft-start branch 107 and / or the second buffer reactor 109, and then connected to the second frequency AC system 102.

[0092] Figure 6 A schematic diagram of a soft-start branch of an exemplary embodiment is shown.

[0093] In the first soft-start branch and the second soft-start branch, at least one soft-start branch adopts a structure including a charging switch, a charging resistor, and a bypass switch. The specific connection method of the soft-start branch is as follows: the charging switch and the charging resistor of the soft-start branch are connected in series, and the bypass switch and the charging resistor are connected in parallel; or the bypass switch of one of the soft-start branches is connected in parallel with the branch in which the charging switch and the charging resistor are connected in series.

[0094] Figure 6 and Figure 7 The diagram shows two connection methods for the first soft starter branch or the second soft starter branch. Components 501 and 601 represent charging switches, components 502 and 602 represent charging resistors, and components 503 and 603 represent bypass switches.

[0095] According to some embodiments, in the first soft start branch and the second soft start branch, at least one soft start branch adopts a structure including a charging switch, a charging resistor and a bypass switch, and the remaining branches adopt an isolating switch; or all soft start branches include a structure including a charging switch, a charging resistor and a bypass switch.

[0096] Figure 8 A schematic diagram of a full-bridge circuit of an exemplary embodiment is shown.

[0097] like Figure 8 As shown, the full-bridge circuit includes an AC port 801, a controllable switching device 802, and a capacitor 803 connected in parallel.

[0098] According to some embodiments, the full-bridge circuit may also include an energy storage element 804, such as a supercapacitor and a battery, connected in parallel with the capacitor element 803.

[0099] Figure 9 A schematic diagram of an isolated matrix converter system of an exemplary embodiment is shown.

[0100] According to some embodiments, the primary winding of a multi-winding transformer is connected to the converter valve bridge arm in the following three forms:

[0101] Form 1: The primary winding of a multi-winding transformer contains only one winding, and the converter valve bridge arm is connected to both ends of the primary winding.

[0102] Form 2: The primary winding of a multi-winding transformer contains multiple windings, which are connected in a star or delta configuration depending on the phase configuration; the converter valve bridge arm has the same number of phases as the primary winding, with one end short-circuited and the other end connected to one phase of the primary winding.

[0103] Form 3: The primary winding of a multi-winding transformer contains multiple windings. The number of converter valve bridge arms is the same as the number of primary windings. Each converter valve bridge arm is connected in series with a primary winding to form a series branch. This branch is then connected to the series branches of the other converter valve bridge arms and the primary windings to form a head-to-tail structure.

[0104] A multi-winding transformer has its first secondary winding connected to the first output port and its second secondary winding connected to the second output port, including the following three forms:

[0105] Form 1: The first secondary winding / second secondary winding of a multi-winding transformer contains only one winding, and the two ends of the first secondary winding / second secondary winding are connected between the two phases of the first output port / second output port;

[0106] Form 2: The system includes multiple multi-winding transformers, and the first secondary winding / secondary winding of the multi-winding transformer contains only one winding. The first secondary winding / secondary winding of the multiple multi-winding transformers are connected in a star connection or delta connection according to the phase configuration and then connected to the first output port / second output port.

[0107] Form 3: The first secondary winding / second secondary winding of a multi-winding transformer contains only multiple windings. Depending on the phase configuration, they are connected in a star or delta configuration and then connected to the corresponding number of phases of the first output port / second output port.

[0108] According to some embodiments, this application optimizes the configuration of magnetic components in the matrix converter system, rationally configures the bridge arm combination, optimizes the operating state of the magnetic components, reduces the magnetic saturation of magnetic devices such as bridge arm reactance or transformers, and integrates the transformers on both sides of the matrix converter system to reduce the system's footprint.

[0109] like Figure 9 As shown, the primary winding adopts form one, and both the first and second secondary windings are of form one; as Figure 10 As shown, the primary winding adopts form two, while the first and second secondary windings are both form three; as Figure 11 As shown, the primary winding adopts form three, and both the first and second secondary windings are form three; as Figure 12As shown, the primary winding adopts form two, the first secondary winding adopts form three, and the second secondary winding adopts form two.

[0110] According to some embodiments, such as Figure 10 As shown, the isolated matrix converter system includes three multi-winding transformers, namely, the primary winding, the first secondary winding, and the second secondary winding, each with three windings, connected in a star or delta configuration, and nine converter valve arms. The first output port includes three phases A, B, and C, and the second output port includes three phases a, b, and c. The phase numbers of the primary windings of the three multi-winding transformers are denoted as phases 1-9, and each phase number corresponds to one primary winding, one first secondary winding, and one second secondary winding.

[0111] Phases 1, 2, and 3 are located in the first multi-winding transformer; phases 4, 5, and 6 are located in the second multi-winding transformer; phases 7, 8, and 9 are located in the third multi-winding transformer. The system connection is as follows:

[0112] One end of the first secondary winding of phase 1 is connected to the first output port A phase, and one end of the second secondary winding is connected to the second output port a phase;

[0113] One end of the first secondary winding of phase 2 is connected to the first output port phase B, and one end of the second secondary winding is connected to the second output port phase b.

[0114] One end of the first secondary winding of phase 3 is connected to the first output port C phase, and one end of the second secondary winding is connected to the second output port C phase;

[0115] One end of the first secondary winding of phase 4 is connected to the first output port A phase, and one end of the second secondary winding is connected to the second output port b phase;

[0116] One end of the first secondary winding of phase 5 is connected to the first output port phase B, and one end of the second secondary winding is connected to the second output port phase c.

[0117] One end of the first secondary winding of phase 6 is connected to the first output port phase C, and one end of the second secondary winding is connected to the second output port phase a.

[0118] One end of the first secondary winding of phase 7 is connected to the first output port A phase, and one end of the second secondary winding is connected to the second output port c phase;

[0119] One end of the first secondary winding of phase 8 is connected to the first output port phase B, and one end of the second secondary winding is connected to the second output port phase a.

[0120] One end of the first secondary winding of phase 9 is connected to the first output port C phase, and one end of the second secondary winding is connected to the second output port b phase.

[0121] According to some embodiments, this application analyzes the operating current characteristics of the matrix converter, rationally selects appropriate converter valve bridge arms, and groups them. After grouping, the mixing current in the converter valve bridge arms can achieve three-phase balance in two frequency dimensions. Furthermore, a three-winding transformer can be constructed using the three-phase balanced current. After connecting certain phases, the mixing current of the transformer is short-circuited in two frequency dimensions to output the frequency after frequency switching. For the three windings of the transformer, although the operating current is the mixing frequency, magnetic balance can be achieved on both sides due to the current balance design. Therefore, the design requirements of the three-winding transformer can be reduced, and the isolation function of the two sides of the frequency switching valve and the valve can be completed. It can also indirectly reduce its cost and footprint.

[0122] Figure 13 A flowchart illustrating a control method for an isolated matrix converter system of an exemplary embodiment is shown.

[0123] According to some embodiments, the control process of an isolated matrix converter system includes starting from a first frequency AC system 101 and starting from a second frequency AC system 102.

[0124] According to some embodiments, if the input side of the isolated matrix converter system is a three-phase AC system at the first frequency, the startup process is as follows:

[0125] S11: If there is an isolating switch in the first soft starter branch and the second soft starter branch, close the isolating switch; otherwise, skip this step.

[0126] S12: Close the charging switch of the first soft starter branch, and after the converter valve bridge arm module has completed charging, close the bypass switch of the first soft starter branch.

[0127] S13: Unlock the converter valve bridge arm;

[0128] S14: The second soft starter branch is an isolating switch, and the start-up process has ended;

[0129] According to some embodiments, if the second soft start branch is an isolating switch, the start-up ends; if the second soft start branch is not an isolating switch, then proceed to S15.

[0130] S15: Close the charging switch of the second soft starter branch, and after a delay, close the bypass switch of the second soft starter branch to end the start-up process.

[0131] Figure 14 Another embodiment of a control method flowchart for an exemplary isolated matrix converter system is shown.

[0132] According to some embodiments, if the input side of the isolated matrix converter system is a second-frequency three-phase AC system, the startup process is as follows:

[0133] S21: If there is an isolating switch in the first soft starter branch and the second soft starter branch, close the isolating switch; otherwise, skip this step.

[0134] S22: Close the charging switch of the second soft starter branch, and after the converter valve bridge arm module has completed charging, close the bypass switch of the second soft starter branch.

[0135] S23: Unlock the converter valve bridge arm;

[0136] S24: The first soft starter branch is an isolating switch, and the start-up process has ended;

[0137] According to some embodiments, if the first soft start branch is an isolating switch, the start-up ends; if the first soft start branch is not an isolating switch, then proceed to S25.

[0138] S25: Close the charging switch of the first soft starter branch, and after a delay, close the bypass switch of the first soft starter branch to end the start-up process.

[0139] It should be clearly understood that this application describes how specific examples are formed and used, but this application is not limited to any details of these examples. Rather, based on the teachings of the disclosure of this application, these principles can be applied to many other embodiments.

[0140] Furthermore, it should be noted that the above figures are merely illustrative representations of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0141] Exemplary embodiments of this application have been specifically shown and described above. It should be understood that this application is not limited to the detailed structures, arrangements, or implementation methods described herein; rather, this application is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. A control method for an isolated matrix converter system, the isolated matrix converter system comprising a first soft-start branch and a second soft-start branch, wherein one of the first soft-start branch and the second soft-start branch comprises a charging switch, a charging resistor, and a bypass switch, and the other soft-start branch comprises an isolating switch; or both the first soft-start branch and the second soft-start branch comprise the charging switch, the charging resistor, and the bypass switch; a first frequency AC system, a second frequency AC system, a first output port, a second output port, at least one converter valve bridge arm, and at least one multi-winding transformer, the multi-winding transformer comprising a primary winding, a first secondary winding, and a second secondary winding, the primary winding being connected to the converter valve bridge arm, the first secondary winding being connected to the first output port, and the second secondary winding being connected to the second output port, characterized in that... The control method for the isolated matrix converter system includes: Start from the first frequency AC system or start from the second frequency AC system; The initiation from the first frequency AC system includes: If the first soft starter branch or the second soft starter branch includes a disconnect switch, then the disconnect switch is closed; Close the charging switch of the first soft starter branch; In response to the completion of charging of the converter valve bridge arm, the bypass switch of the first soft start branch is closed; Unlock the converter valve bridge arm; Close the charging switch of the second soft starter branch and close the bypass switch of the second soft starter branch.

2. The control method as described in claim 1, characterized in that, The initiation from the second frequency AC system includes: If the second soft starter branch or the first soft starter branch includes an isolating switch, then the isolating switch is closed; Close the charging switch of the second soft start branch; In response to the completion of charging of the converter valve bridge arm, the bypass switch of the second soft start branch is closed; Unlock the converter valve bridge arm; Close the charging switch of the first soft starter branch and close the bypass switch of the first soft starter branch.

3. An isolated matrix converter system, characterized in that, The isolated matrix converter system is used to execute the control method as described in claim 1 or 2, and the isolated matrix converter system includes: First output port; Second output port; At least one converter valve bridge arm, At least one multi-winding transformer, the multi-winding transformer comprising: a primary winding, a first secondary winding, and a second secondary winding; The primary winding is connected to the converter valve bridge arm; the first secondary winding is connected to the first output port; and the second secondary winding is connected to the second output port.

4. The isolated matrix converter system as described in claim 3, characterized in that, Also includes: The bridge arm reactor is connected in series with the converter valve bridge arm.

5. The isolated matrix converter system as described in claim 3, characterized in that, Also includes: The first frequency AC system is connected to the first output port in phase order; as well as The second frequency AC system is connected to the second output port in phase order.

6. The isolated matrix converter system as described in claim 5, characterized in that, It also includes a first buffer reactance and a second buffer reactance, wherein, The first output port of the matrix converter system is connected to the first buffer reactor in phase order, and then connected to the first frequency AC system. The second output port of the matrix converter system is connected to the second buffer reactor in phase order, and then connected to the second frequency AC system.

7. The isolated matrix converter system as described in claim 6, characterized in that, It also includes a first soft starter branch and a second soft starter branch, wherein, The first output port of the isolated matrix converter system is connected to the first soft-start branch and then to the first frequency AC system. The second output port of the isolated matrix converter system is connected to the second soft-start branch and then to the second frequency AC system.

8. The isolated matrix converter system as described in claim 7, characterized in that, One of the first soft-start branch and the second soft-start branch includes a charging switch, a charging resistor, and a bypass switch, and the other soft-start branch includes an isolating switch; or Both the first soft-start branch and the second soft-start branch include the charging switch, the charging resistor, and the bypass switch; Wherein, the charging switch is connected in series with the charging resistor, and the bypass switch is connected in parallel with the charging resistor; or The bypass switch is connected in parallel with the branch of the charging switch and the charging resistor that are connected in series.

9. The isolated matrix converter system as described in claim 3, characterized in that, The primary winding connecting the converter valve bridge arm includes: The primary winding of the multi-winding transformer consists of only one winding, and the converter valve bridge arm is connected to both ends of the primary winding; or The primary winding of the multi-winding transformer includes multiple windings, which are connected in a star or delta configuration depending on the phase. The number of phases of the converter valve bridge arm is the same as that of the primary winding, and one end of the converter valve bridge arm is short-circuited while the other end is connected to one phase of the primary winding; or The converter valve bridge arm and the primary winding form a series branch, which is connected end to end with the other series branches.

10. The isolated matrix converter system as described in claim 9, characterized in that, The first secondary winding is connected to the first output port, and the second secondary winding is connected to the second output port, including: The first secondary winding / second secondary winding of the multi-winding transformer includes only one winding, and the two ends of the first secondary winding / second secondary winding are connected between the two phases of the first output port / second output port; or The isolated matrix converter system includes multiple multi-winding transformers, and the first secondary winding / second secondary winding of each multi-winding transformer includes only one winding. The first secondary winding / second secondary windings of the multiple multi-winding transformers are connected in a star or delta configuration according to the phase configuration, and then connected to the first output port / second output port; or The first secondary winding / second secondary winding of the multi-winding transformer includes multiple windings, which are connected in a star or delta configuration according to the phase configuration, and then connected to the corresponding phases of the first output port / second output port.

11. The isolated matrix converter system as described in claim 10, characterized in that: The primary winding, first secondary winding, or second secondary winding of the multi-winding transformer adopts the star connection method, and the grounding method includes: direct grounding, grounding through the target coil, grounding through the target resistor, or no grounding; or The grounding method adopts a delta connection and includes: grounding through a Z-type transformer, grounding through three reactors, or no grounding.

12. The isolated matrix converter system as described in claim 3, characterized in that, The converter valve bridge arm includes N sub-modules connected in series, where N is a positive integer greater than or equal to 1; The submodule includes a full-bridge circuit, and each submodule is connected in series through an AC port.

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