Frequency converter system, module series type frequency converter, working method of module series type frequency converter and computer readable storage medium

Abstract

The invention provides a module series frequency converter and a working method thereof, a frequency converter system and a computer readable storage medium. The module series frequency converter comprises: a main controller; the photoelectric conversion circuit comprises a first photoelectric conversion circuit which is in communication connection with the main controller through a first optical fiber; each power unit group comprises a plurality of power units and at least comprises a first power unit and a second power unit, and the first power unit is connected with the first photoelectric conversion circuit; three isolation device groups, wherein each isolation device group comprises one or more isolation devices; the power unit groups are in one-to-one correspondence with the isolation device groups, and in each power unit group, the first power unit is in communication connection with the second power unit through the isolation device. According to the module series-connection type frequency converter, the power units in the same group are connected through the isolation devices and the wires, use of optical fibers and optical fiber transceivers can be reduced, cost is reduced, communication faults caused by the optical fibers are reduced, and reliability and competitiveness of the frequency converter are improved.

Description

Technical Field

[0001] This invention relates generally to the field of frequency converter technology, and more particularly to a modular series frequency converter, a method for operating a modular series frequency converter, a frequency converter system, and a computer-readable storage medium. Background Technology

[0002] With the progress of industrialization and the development of power technology, modular series frequency converters are widely used in various industries.

[0003] Modular series frequency converters consist of multiple power units connected in series. In some existing solutions, all power units are connected to the main controller via fiber optic communication, or power units are connected to each other via fiber optic communication. This connection method results in excessively high costs and complex wiring for modular series frequency converters. Furthermore, fiber optic communication is significantly affected by the environment, and communication problems are prone to occur in corrosive or dusty environments. How to reduce the cost of modular series frequency converters and improve the reliability of communication connections is the technical problem that this invention aims to solve.

[0004] The content of the background section is merely the technology known to the inventor and does not necessarily represent the prior art in this field. Summary of the Invention

[0005] To address one or more of the problems existing in the prior art, the present invention provides a modular series frequency converter, comprising:

[0006] Main controller;

[0007] The photoelectric conversion circuit includes a first photoelectric conversion circuit, which is connected to the main controller via a first optical fiber.

[0008] Three power unit groups, each power unit group comprising multiple power units, wherein the multiple power units include at least a first power unit and a second power unit, wherein the first power unit is connected to the first photoelectric conversion circuit; and

[0009] Three isolation device groups, each of which includes one or more isolation devices;

[0010] The power unit group and the isolation device group correspond one-to-one. In each power unit group, the first power unit is communicatively connected to the second power unit through the isolation device.

[0011] Optionally, each isolation device group includes multiple isolation devices, and the multiple isolation devices include at least a first isolation device and a second isolation device, wherein the first power unit is connected to the first photoelectric conversion circuit through the first isolation device.

[0012] Optionally, the main controller is configured to send a control signal, which is transmitted to the first photoelectric conversion circuit via the first optical fiber. The first photoelectric conversion circuit is configured to perform photoelectric conversion on the control signal and send the converted control signal to the first isolation device.

[0013] Optionally, the first power unit includes a first controller, the second power unit includes a second controller, the first isolation device is configured to receive the converted control signal from the first photoelectric conversion circuit, and send the converted control signal to the first controller and the second isolation device; the first controller is configured to receive the converted control signal from the first isolation device, and the second controller is configured to receive the converted control signal from the second isolation device.

[0014] Optionally, the first power unit includes a first controller, the second power unit includes a second controller, the first isolation device is configured to receive the converted control signal from the first photoelectric conversion circuit and send the converted control signal to the first controller; the first controller is configured to receive the converted control signal from the first isolation device and send the converted control signal to the second isolation device, and the second controller is configured to receive the converted control signal from the second isolation device.

[0015] Optionally, each isolation device group further includes a third isolation device and a fourth isolation device, wherein the third isolation device connects the second power unit to the first power unit, and the fourth isolation device connects the first power unit to the first photoelectric conversion circuit.

[0016] Optionally, the second controller is configured to determine the status information of the second power unit and send the status information of the second power unit to the third isolation device; the third isolation device is configured to receive the status information of the second power unit and send the status information of the second power unit to the first controller; the first controller is configured to receive the status information of the second power unit and send the status information of the second power unit to the fourth isolation device.

[0017] Optionally, the second controller is configured to determine the status information of the second power unit and send the status information of the second power unit to the third isolation device; the third isolation device is configured to receive the status information of the second power unit and send the status information of the second power unit to the fourth isolation device.

[0018] Optionally, the first controller is further configured to determine the status information of the first power unit and send the status information of the first power unit to the fourth isolation device.

[0019] Optionally, the fourth isolation device is configured to receive status information of the first power unit and / or the second power unit, and send the status information of the first power unit and / or the second power unit to the first photoelectric conversion circuit; the first photoelectric conversion circuit is configured to receive the status information of the first power unit and / or the second power unit from the fourth isolation device, and after photoelectric conversion, send it to the main controller via the first optical fiber.

[0020] Optionally, the photoelectric conversion circuit further includes a second photoelectric conversion circuit, which is connected to the second power unit and the main controller.

[0021] Optionally, the first controller is configured to determine the status information of the first power unit and send the status information of the first power unit to the second isolation device; the second isolation device is configured to receive the status information of the first power unit and send the status information of the first power unit to the second controller; the second controller is configured to receive the status information of the first power unit and send the status information of the first power unit to the second photoelectric conversion circuit.

[0022] Optionally, the first controller is configured to determine the status information of the first power unit and send the status information of the first power unit to the second isolation device; the second isolation device is configured to receive the status information of the first power unit and send the status information of the first power unit to the second photoelectric conversion circuit.

[0023] Optionally, the second controller is configured to determine the status information of the second power unit and send the status information of the second power unit to the second photoelectric conversion circuit.

[0024] Optionally, each isolation device group further includes: a fifth isolation device, the fifth isolation device connecting the second power unit and the second photoelectric conversion circuit, the second photoelectric conversion circuit being connected to the main controller via a second optical fiber; the status information of the first power unit and / or the second power unit being sent to the second photoelectric conversion circuit via the fifth isolation device; the second photoelectric conversion circuit being configured to receive the status information of the first power unit and / or the second power unit, perform photoelectric conversion on it, and then send it to the main controller via the second optical fiber.

[0025] Optionally, the photoelectric conversion circuit is disposed outside or inside the power unit; the first photoelectric conversion circuit is disposed outside or inside the first power unit.

[0026] Optionally, the second photoelectric conversion circuit is disposed outside or inside the second power unit.

[0027] Optionally, the isolation device is disposed outside or inside the power unit.

[0028] Optionally, the isolation device is disposed outside or inside the photoelectric conversion circuit.

[0029] Optionally, the isolation device includes at least one of an optical isolator, a magnetic coupling isolator, and a capacitive isolator.

[0030] Optionally, each power unit has an independent communication address, and the main controller is configured to communicate with the power unit based on the communication address and a private protocol; the power units communicate with each other based on the private protocol.

[0031] The present invention also provides a frequency converter system, including the module series frequency converter described above.

[0032] The present invention also provides a method for operating a modular series frequency converter, comprising:

[0033] The main controller of the series inverter in the module sends control signals;

[0034] The control signal is transmitted to the first photoelectric conversion circuit via the first optical fiber;

[0035] The control signal is photoelectrically converted by the first photoelectric conversion circuit;

[0036] The converted control signals are sent to the first power unit of each of the three power unit groups; and

[0037] The control signal is sent to the second power unit of the three power unit groups through the isolation devices in the three isolation device groups respectively.

[0038] Optionally, each isolation device group includes multiple isolation devices, the multiple isolation devices including at least a first isolation device and a second isolation device, and the first power unit is connected to the first photoelectric conversion circuit through the first isolation device; the operating method includes: sending the photoelectric converted control signal to the first isolation device of each of the three isolation device groups respectively.

[0039] Optionally, the first power unit includes a first controller, the second power unit includes a second controller, and the operating method further includes:

[0040] The converted control signal is received from the first photoelectric conversion circuit via the first isolation device, and the converted control signal is sent to the first controller and the second isolation device; the converted control signal is received from the first isolation device via the first controller; the converted control signal is received from the second isolation device via the second controller; or

[0041] The first isolation device receives the converted control signal from the first photoelectric conversion circuit and sends the converted control signal to the first controller; the first controller receives the converted control signal from the first isolation device and sends the converted control signal to the second isolation device; the second controller receives the converted control signal from the second isolation device.

[0042] Optionally, each isolation device group further includes a third isolation device and a fourth isolation device, wherein the third isolation device connects the second power unit and the first power unit, and the fourth isolation device connects the first power unit and the first photoelectric conversion circuit; the operating method further includes:

[0043] The second controller determines the status information of the second power unit and sends the status information of the second power unit to the third isolation device; the third isolation device receives the status information of the second power unit and sends the status information of the second power unit to the first controller; the first controller receives the status information of the second power unit and sends the status information of the second power unit to the fourth isolation device; or

[0044] The second controller determines the status information of the second power unit and sends the status information of the second power unit to the third isolation device; the third isolation device receives the status information of the second power unit and sends the status information of the second power unit to the fourth isolation device.

[0045] Optionally, the working method further includes: determining the status information of the first power unit through the first controller and sending the status information of the first power unit to the fourth isolation device; receiving the status information of the first power unit and / or the second power unit through the fourth isolation device and sending the status information of the first power unit and / or the second power unit to the first photoelectric conversion circuit; receiving the status information of the first power unit and / or the second power unit from the fourth isolation device through the first photoelectric conversion circuit, performing photoelectric conversion on it, and then sending it to the main controller via the first optical fiber.

[0046] Optionally, the modular series inverter further includes: a second photoelectric conversion circuit, the second photoelectric conversion circuit being connected to the second power unit and the main controller; the operating method further includes:

[0047] The first controller determines the status information of the first power unit and sends the status information of the first power unit to the second isolation device; the second isolation device receives the status information of the first power unit and sends the status information of the first power unit to the second controller; the second controller receives the status information of the first power unit and sends the status information of the first power unit to the second photoelectric conversion circuit; or

[0048] The first controller determines the status information of the first power unit and sends the status information of the first power unit to the second isolation device; the second isolation device receives the status information of the first power unit and sends the status information of the first power unit to the second photoelectric conversion circuit.

[0049] Optionally, the working method further includes: determining the status information of the second power unit through the second controller, and sending the status information of the second power unit to the second photoelectric conversion circuit.

[0050] Optionally, each isolation device group further includes: a fifth isolation device, the fifth isolation device connecting the second power unit and the second photoelectric conversion circuit, the second photoelectric conversion circuit being connected to the main controller via a second optical fiber; the operating method further includes: sending the status information of the first power unit and / or the second power unit to the second photoelectric conversion circuit through the fifth isolation device; receiving the status information of the first power unit and / or the second power unit through the second photoelectric conversion circuit, performing photoelectric conversion on it, and then sending it to the main controller via the second optical fiber.

[0051] The present invention also provides a computer-readable storage medium including computer-executable instructions stored thereon, the executable instructions performing the working method as described above when executed by a processor.

[0052] The modular series inverter of the present invention connects the power units in the same group through isolation devices and wires. Compared with the prior art (e.g., each power unit is directly connected to the main controller through optical fiber or in a ring connection), it can significantly reduce the use of optical fibers and optical fiber transceivers, effectively reduce the cost of the inverter, and at the same time, reduce communication failures caused by optical fibers (e.g., plastic optical fibers) in humid, corrosive, and high-dust environments, improve the communication quality of the inverter, improve the reliability of the inverter, and enhance the competitiveness of the inverter. Attached Figure Description

[0053] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0054] Figure 1 A schematic diagram of a modular series frequency converter according to some embodiments of the present invention is shown.

[0055] Figure 2 A schematic diagram of a modular series frequency converter according to other embodiments of the present invention is shown.

[0056] Figure 3 A topological schematic diagram of a power unit according to some embodiments of the present invention is shown.

[0057] Figure 4 A schematic diagram of a power unit receiving control signals according to some embodiments of the present invention is shown.

[0058] Figure 5 A schematic diagram of a power unit receiving control signals according to other embodiments of the present invention is shown.

[0059] Figures 6 to 9 A schematic diagram illustrating the transmission of status information by a power unit according to some embodiments of the present invention is shown.

[0060] Figure 10 and Figure 11 A schematic diagram showing the positional relationship between the photoelectric conversion circuit and the power unit according to some embodiments of the present invention is provided.

[0061] Figure 12 and Figure 13 A schematic diagram showing the positional relationship between the isolation device and the photoelectric conversion circuit according to some embodiments of the present invention is shown.

[0062] Figure 14A schematic diagram showing the positional relationship between the isolation device, the photoelectric conversion circuit, and the power unit according to some embodiments of the present invention is shown.

[0063] Figure 15 A schematic diagram of a modular series frequency converter according to some embodiments of the present invention is shown.

[0064] Figure 16 A schematic diagram of a modular series frequency converter according to yet another embodiment of the present invention is shown.

[0065] Figure 17 A schematic diagram of a frequency converter system according to some embodiments of the present invention is shown.

[0066] Figure 18 A flowchart illustrating the operation method of a modular series frequency converter according to some embodiments of the present invention is shown. Detailed Implementation

[0067] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0068] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0069] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "coupling" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0071] The following provides many different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure of the invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in the present invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0072] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0073] This invention provides a modular series frequency converter. The modular series frequency converter includes a main controller, a photoelectric conversion circuit, three isolation device groups, and three power unit groups. The photoelectric conversion circuit includes a first photoelectric conversion circuit, which is connected to the main controller via a first optical fiber. Each of the three isolation device groups includes one or more isolation devices. Each of the three power unit groups includes multiple power units. The multiple power units include at least a first power unit and a second power unit. The first power unit is connected to the first photoelectric conversion circuit. The power unit groups correspond one-to-one with the isolation device groups; in each power unit group, the first power unit is communicatively connected to the second power unit via an isolation device.

[0074] The modular series inverter of this invention connects power units within the same group via isolation devices and wires. Compared to existing technologies (e.g., each power unit is directly or in a ring connection with the main controller via optical fiber), this significantly reduces the use of optical fibers and optical transceivers, effectively lowering the inverter's cost. Furthermore, it reduces communication failures caused by optical fibers (e.g., plastic optical fibers) in humid, corrosive, or dusty environments, improving the inverter's communication quality, reliability, and competitiveness. A detailed description follows.

[0075] Figure 1 A schematic diagram of a modular series frequency converter 1000 according to some embodiments of the present invention is shown. Figure 1As shown, the modular series frequency converter 1000 includes a main controller 10, a photoelectric conversion circuit 20, an isolation device group 30, and a power unit group 40. The photoelectric conversion circuit 20 includes a first photoelectric conversion circuit 20-1, which is connected to the main controller 10 via a first optical fiber F. The photoelectric conversion circuit 20 may include, for example, an optical fiber communication transceiver and transceiver circuit. The power unit group 40 includes three power unit groups 40A, 40B, and 40C. The input of the main circuit of power unit groups 40A to 40C can be connected to the transformer output (not shown in the figure). Each power unit group includes multiple power units, and each power unit includes at least a first power unit and a second power unit. For example, power unit group 40A includes a first power unit 401A and a second power unit 402A; power unit group 40B includes a first power unit 401B and a second power unit 402B; and power unit group 40C includes a first power unit 401C and a second power unit 402C. Isolation device group 30 includes one or more isolation devices 300 (one isolation device is shown in the figure). There is a one-to-one correspondence between power unit groups and isolation device groups. In each power unit group, the first power unit is connected to the second power unit 402 via an isolation device 300 (and a wire). For example, in power unit group 40A, the first power unit 401A is connected to the second power unit 402A via an isolation device 300 (and a wire). In other words, within the same power unit group, power units are connected to each other via isolation devices (and wires). Connecting power units within the same power unit group via isolation devices reduces the use of optical fibers and optical fiber transceivers, lowers the cost of the frequency converter, and improves the communication reliability between power units within the same power unit group, thereby reducing the cost of the frequency converter and improving its reliability.

[0076] Figure 2 A schematic diagram of a modular series frequency converter 2000 according to other embodiments of the present invention is shown. Figure 1 and 2As shown, the modular series inverter 2000 is largely the same as the modular series inverter 1000; the differences between the two are described in detail below. The isolation device group 30 includes multiple isolation devices. For example, the multiple isolation devices include at least a first isolation device 301 and a second isolation device 302. In each power unit group, a first power unit is connected to a first photoelectric conversion circuit 20-1 via a first isolation device 301 (and a wire), and is connected to a second power unit 402 via a second isolation device 302 (and a wire). For example, in power unit group 40A, a first power unit 401A is connected to the first photoelectric conversion circuit 20-1 via a first isolation device 301 (and a wire), and is connected to a second power unit 402A via a second isolation device 302 (and a wire). In other words, within the same power unit group, power units are connected to each other via isolation devices (and wires), and a first power unit is connected to the first photoelectric conversion circuit via an isolation device (and a wire). In this way, not only can the use of optical fibers and optical fiber transceivers be reduced, the cost of frequency converters be lowered, and the communication reliability between power units in the same power unit group be improved, but the communication reliability between the first power unit and the first photoelectric conversion circuit can also be improved.

[0077] In the modular series inverter of the present invention, power units in different groups are connected only at the neutral point via isolation devices (and wires), for example, the first power unit in each power unit group (see...). Figure 2 The output terminals of the first power units 401A, 401B, and 401C (not shown in the figure) are connected together to form the neutral point of the three-phase output of the frequency converter, which is beneficial to the stable operation of the frequency converter and improves its reliability.

[0078] Figure 3 A topological schematic diagram of a power unit according to some embodiments of the present invention is shown. For example... Figure 3 As shown, the power unit's rectifier side uses diodes (e.g., D1 to D6) for three-phase (R, S, T) full-wave rectification; intermediate capacitors (e.g., C1 to Cn, where n is a positive integer) are used for filtering and energy storage; the output side uses an inverter bridge composed of insulated-gate bipolar transistors (e.g., IGBT1 to IGBT4) to convert the DC input to AC output, for example, providing a single-phase constant-amplitude AC PWM waveform output voltage. The inverter bridge can be an H-bridge or a three-level H-bridge, etc. The rectifier side input of the power unit may include protection circuitry, for example... Figure 3 The embodiments shown include fuses Fuse1 and Fuse2. It should be noted that the devices inside the power unit are not limited to... Figure 3As illustrated in the embodiments, other devices may also be included, and the number of each device and their connection relationship can be adjusted according to the actual situation, all of which are within the protection scope of the present invention.

[0079] In some embodiments, each power unit may include a controller. For convenience, power unit group 40A is described below as an example. It should be understood that examples of power unit groups 40B and 40C are the same as or similar to those of power unit group 40A.

[0080] Figure 4 A schematic diagram illustrating the receiving of control signals by a power unit according to some embodiments of the present invention is shown. For example... Figure 4 As shown, the first power unit 401A includes a first controller C1, and the second power unit 402A includes a second controller C2. The main controller 10 can send control signals (e.g., optical control signals containing three-phase PWM information). These control signals are sent to the first photoelectric conversion circuit 20-1 via the first optical fiber F. The first photoelectric conversion circuit 20-1 performs photoelectric conversion on the control signal and sends the converted control signal to the first isolation device 301. The first isolation device 301 receives the converted control signal from the first photoelectric conversion circuit 20-1 and sends it to the first power unit 401A.

[0081] In some embodiments, such as Figure 4 As shown, the first isolation device 301 receives the converted control signal from the first photoelectric conversion circuit 20-1 and sends the converted control signal to the first controller C1 and the second isolation device 302. The first controller C1 receives the control signal from the first isolation device 301. The second controller C2 receives the control signal from the second isolation device 302. That is, the control signal converted by the first photoelectric conversion circuit can be directly sent to the second controller (second power unit) through the isolation device without being forwarded by the first controller (first power unit). In other words, the control signal converted by the first photoelectric conversion circuit can be sent in parallel to each power unit through the isolation device without being forwarded by the power unit level by level, ensuring the communication rate and real-time performance between the main controller and the power units, and between the power units.

[0082] In other embodiments, such as Figure 5As shown, the first isolation device 301 receives the control signal from the first photoelectric conversion circuit 20-1 and sends the control signal to the first controller C1. The first controller C1 receives the control signal from the first isolation device 301 and sends the control signal to the second isolation device 302. The second controller C2 receives the converted control signal from the second isolation device 302. That is, the control signal converted by the first photoelectric conversion circuit can be forwarded to the second controller (second power unit) through the first controller (first power unit). In other words, the control signal converted by the first photoelectric conversion circuit can be forwarded (processed or not processed) to each power unit through the power units step by step. It can be forwarded directly, or it can be processed (such as inserting its own power unit's status information) before forwarding, ensuring the communication flexibility between power units.

[0083] In some embodiments, such as Figure 2 As shown, each isolation device group 30 further includes a third isolation device 303 and a fourth isolation device 304. The third isolation device 303 connects the second power unit (e.g., 402A) to the first power unit (e.g., 401A). The fourth isolation device 304 connects the first power unit (e.g., 401A) to the first photoelectric conversion circuit 20-1. Preferably, the isolation devices may also include devices such as amplifiers (e.g., Figure 2 (As shown in the diagram of the triangle in the middle), the amplifier is connected to the isolation device. It can be integrated inside the isolation device or placed outside the isolation device. In practical applications, it can be set according to the requirements.

[0084] In some embodiments, such as Figure 6As shown, the second controller C2 can determine the status information of the second power unit 402A and send the status information of the second power unit 402A to the third isolation device 303. The third isolation device 303 receives the status information of the second power unit 402A and sends the status information of the second power unit 402A to the first controller C1. The first controller C1 receives the status information of the second power unit 402A and sends the status information of the second power unit 402A to the fourth isolation device 304. The fourth isolation device 304 receives the status information of the second power unit 402A and sends the status information of the second power unit 402A to the first photoelectric conversion circuit 20-1. The first photoelectric conversion circuit 20-1 receives the status information of the second power unit 402A from the fourth isolation device 304, performs photoelectric conversion on the status information of the second power unit 402A, and then sends it to the main controller 10 via the first optical fiber F. That is to say, the status information of the second power unit can be forwarded to the first photoelectric conversion circuit through the first power unit (first controller). In other words, a power unit can send its own status information to other power units step by step, and the other power units will receive and forward (process or not process) it to the photoelectric conversion circuit.

[0085] In other embodiments, such as Figure 7 As shown, the second controller C2 determines the status information of the second power unit 402A and sends it to the third isolation device 303. The third isolation device 303 receives the status information of the second power unit 402A and sends it to the fourth isolation device 304. The fourth isolation device 304 receives the status information of the second power unit 402A and sends it to the first photoelectric conversion circuit 20-1. The first photoelectric conversion circuit 20-1 receives the status information of the second power unit 402A from the fourth isolation device 304, performs photoelectric conversion on the status information of the second power unit 402A, and then sends it to the main controller 10 via the first optical fiber F. In other words, the status information of the second power unit can be directly sent to the first photoelectric conversion circuit through the isolation device without being forwarded by the first power unit (first controller). In other words, the power unit can send its own status information to the photoelectric conversion circuit in parallel through the isolation device, without the power unit forwarding it step by step, ensuring communication speed and real-time performance.

[0086] It should be noted that, referring to Figure 7The output signals of the first controller C1 and the isolation device 303 are simultaneously connected to the input terminal (e.g., input pin, not shown in the figure) of the fourth isolation device 304. Considering potential signal conflicts, preferably, the modular series inverter of this embodiment may include a switching circuit (not shown in the figure). The switching circuit can be connected between the two output terminals and one input terminal to resolve high / low level conflicts and / or task priority conflicts between the two output terminals. The switching circuit may include an open collector gate (OC), an open drain gate (OD), or similar circuits. The switching circuit can be separate from the isolation device and the controller, or it can be integrated into the isolation device or the controller, depending on the requirements.

[0087] For example, refer to Figure 7 The input of the switching circuit (not shown) can be connected to the output of the first controller C1 and the third isolation device 303, and the output of the switching circuit can be connected to the input of the fourth isolation device 304. The switching circuit can resolve high / low level conflicts and / or task priority conflicts between the output signals of the first controller C1 and the third isolation device 303 through high / low level conversion. For example, if the first controller C1 outputs a high level and the third isolation device 303 outputs a low level, there is a high / low level conflict. The switching circuit (e.g., an open-collector gate) can convert the high-level input (from the first controller C1) to a low-level output to resolve the high / low level conflict. The first controller C1 can continuously monitor the output level of the switching circuit. When it determines that the switching circuit outputs a low level, the first controller C1 pauses data transmission, and the third isolation device 303 prioritizes sending data to the fourth isolation device 304. After the third isolation device finishes sending data, the output level of the switching circuit becomes high, and the first controller C1 then sends data to the fourth isolation device 304, thereby resolving the task priority conflict. In other words, switching circuits (e.g., open-collector gates) can resolve level conflicts by converting a high-level input to a low-level output. It should be understood that switching circuits (e.g., closed-collector gates) can also resolve level conflicts by converting a low-level input to a high-level output. The first controller can resolve task conflicts by pausing data transmission when it detects a low-level output from the switching circuit and transmitting data when it detects a high-level output. Task priorities can be set based on the power unit's status information (how to determine the power unit's status information will be described later), depending on the specific circumstances.

[0088] In short, the switching circuit can resolve level conflicts by switching between high and low levels, and the controller can resolve task conflicts by monitoring whether the output level of the switching circuit matches its own output level. When the output level of the switching circuit matches the controller's own output level, the controller can send data; when the output level of the switching circuit does not match its own output level, the controller can pause data transmission and give priority to other tasks. This enables the modular series inverter to have conflict detection and conflict resolution functions, thereby achieving stable and reliable operation and improving the robustness of the modular series inverter.

[0089] The modular series inverter of the present invention adopts a communication mechanism similar to IIC. The controller of the power unit can include both signal input and signal output terminals, and the signal input and signal output terminals can be combined into one. The power unit can realize conflict detection and conflict resolution functions through the controller and the switching circuit.

[0090] In some embodiments, such as Figure 6 and Figure 7 As shown, the first controller C1 determines the status information of the first power unit 401A and sends the status information of the first power unit 401A to the fourth isolation device 304. The fourth isolation device 304 receives the status information of the first power unit 401A and sends the status information of the first power unit 401A to the first photoelectric conversion circuit 20-1. The first photoelectric conversion circuit 20-1 receives the status information of the first power unit 401A from the fourth isolation device 304 and sends the status information of the first power unit 401A to the main controller 10 via the first optical fiber F.

[0091] like Figure 6 and Figure 7 As shown, the fourth isolation device 304 can receive the status information of the first power unit 401A and / or the second power unit 402A, and send the status information of the first power unit 401A and / or the second power unit 402A to the first photoelectric conversion circuit 20-1. The first photoelectric conversion circuit 20-1 can receive the status information of the first power unit 401A and / or the second power unit 402A from the fourth isolation device 304, and after photoelectric conversion, send it to the main controller 10 via the first optical fiber F.

[0092] In some embodiments, such as Figure 8 As shown, the photoelectric conversion circuit also includes a second photoelectric conversion circuit 20-2. The second photoelectric conversion circuit 20-2 is connected to the second power unit 402A and the main controller 10. The second photoelectric conversion circuit 20-2 and the main controller 10 are connected through a second optical fiber F'.

[0093] In some embodiments, such as Figure 8As shown, the first controller C1 can determine the status information of the first power unit 401A and send the status information of the first power unit 401A to the second isolation device 302. The second isolation device 302 receives the status information of the first power unit 401A and sends the status information of the first power unit 401A to the second controller C2. The second controller C2 receives the status information of the first power unit 401A and sends the status information of the first power unit 401A to the second photoelectric conversion circuit 20-2. The second controller C2 determines the status information of the second power unit 402A and sends the status information of the second power unit 402A to the second photoelectric conversion circuit 20-2. The second photoelectric conversion circuit 20-2 receives the status information of the first power unit 401A and / or the second power unit 402A, performs photoelectric conversion, and then sends it to the main controller 10 via the second optical fiber F'. That is to say, the status information of the first power unit can be forwarded to the second photoelectric conversion circuit through the second power unit (second controller). In other words, a power unit can send its own status information to other power units step by step, and the other power units will receive and forward (process or not process) it to the photoelectric conversion circuit.

[0094] In some embodiments, such as Figure 9 As shown, the first controller C1 can determine the status information of the first power unit 401A and send the status information of the first power unit 401A to the second isolation device 302. The second isolation device 302 can receive the status information of the first power unit 401A and send the status information of the first power unit 401A to the second photoelectric conversion circuit 20-2. The second controller C2 can determine the status information of the second power unit 402A and send the status information of the second power unit 402A to the second photoelectric conversion circuit 20-2. The second photoelectric conversion circuit 20-2 receives the status information of the first power unit 401A and / or the second power unit 402A, performs photoelectric conversion, and then sends it to the main controller 10 via the second optical fiber F'. That is to say, the status information of the first power unit can be directly sent to the second photoelectric conversion circuit through the isolation device without being forwarded by the second power unit (second controller). In other words, the power unit can send its own status information to the photoelectric conversion circuit in parallel through the isolation device, without the need for power units to forward it step by step, thus ensuring communication speed and real-time performance.

[0095] In some embodiments, such as Figure 8 and Figure 9As shown, each isolation device group also includes a fifth isolation device 305. The fifth isolation device 305 connects the second power unit 402A and the second photoelectric conversion circuit 20-2. The fifth isolation device 305 can receive the status information of the first power unit 401A and / or the second power unit 402A, and send the status information of the first power unit 401A and / or the second power unit 402A to the second photoelectric conversion circuit 20-2. It should be understood that the aforementioned switching circuit may also be included between the output terminals of the second controller C2 and the second isolation device 302 and the input terminal of the fifth isolation device 305 to resolve high and low level conflicts and / or task priority conflicts, similar to the situation described in the previous embodiments, and will not be repeated here.

[0096] In some embodiments, the power unit may include a detection circuit (not shown) for detecting the status information of the power unit. The detection circuit may be coupled to the controller or integrated into the controller. There may be a one-to-one correspondence between power units and detection circuits, or multiple power units may share a single detection circuit; this can be configured according to requirements in practical applications.

[0097] In some embodiments, the detection circuit may include detection circuits for temperature, humidity, voltage, overcurrent, overheat, undervoltage, and phase loss. The detection circuit can detect information such as temperature, humidity, input-side voltage, current, and phase of the power unit, and send the detection results to the controller. The controller can receive the detection results sent by the detection circuit, and based on the detected information and preset thresholds, determine the status information of the power unit and whether the power unit's operating state is normal. Preferably, different thresholds can also be set to determine the abnormality level of the power unit's operating state, and based on the abnormality level, determine the task priority of the power unit.

[0098] After the controller determines the status information of the power unit, it can... Figures 6 to 9 The system sends status information to the main controller in the manner described in the embodiment. After receiving the status information of the power unit, the main controller can analyze and process the status information of the power unit, for example, controlling the power unit with a normal operating status to continue working, and controlling the power unit with an abnormal operating status to suspend working, etc.

[0099] In some embodiments, the photoelectric conversion circuit can be disposed outside or inside the power unit. For example, such as Figure 1 , Figure 2 , Figures 4 to 7 and Figure 15 As shown, the first photoelectric conversion circuit 20-1 is disposed outside the first power unit 401A. For example, as... Figure 10 and Figure 16 As shown, the first photoelectric conversion circuit 20-1 is disposed inside the first power unit 401A.

[0100] In some embodiments, the second photoelectric conversion circuit may be disposed outside or inside the second power unit. For example, such as Figure 8 and Figure 9 As shown, the second photoelectric conversion circuit 20-2 is disposed outside the second power unit 402A. For example, as... Figure 11 As shown, the second photoelectric conversion circuit 20-2 is located inside the second power unit 402A. In practical applications, the position of the photoelectric conversion circuit relative to the power unit can be set according to requirements.

[0101] In some embodiments, the isolation device may be located outside or inside the power unit. For example, such as Figure 1 , Figure 2 , Figures 4 to 9 As shown, isolation device 300 is disposed outside the first power unit 401A and the second power unit 402A; first isolation device 301 and fourth isolation device 304 are disposed inside the first power unit 401A; second isolation device 302 and third isolation device 303 are disposed inside the second power unit 402A; and fifth isolation device 305 is disposed outside the first power unit 401A and the second power unit 402A. In practical applications, the positions of the isolation devices relative to the power units can be set according to requirements.

[0102] In some embodiments, the isolation device may be disposed outside or inside the photoelectric conversion circuit. For example, such as Figure 1 , Figure 2 , Figures 4 to 7 As shown, isolation device 300, first isolation device 301, second isolation device 302, third isolation device 303, and fourth isolation device 304 are disposed outside the first photoelectric conversion circuit 20-1. Figure 8 and Figure 9 As shown, the fifth isolation device 305 is disposed outside the second photoelectric conversion circuit 20-2. For example, as... Figure 12 As shown, the first isolation device 301 is disposed inside the first photoelectric conversion circuit 20-1. For example, as... Figure 13 As shown, the fifth isolation device 305 is disposed inside the second photoelectric conversion circuit 20-2. In practical applications, the position of the isolation device relative to the photoelectric conversion circuit can be set according to requirements.

[0103] In some embodiments, the isolation device can be disposed outside or inside the photoelectric conversion circuit, and the photoelectric conversion circuit can be disposed outside or inside the power unit. For example, such as Figure 14As shown, the first isolation device 301 is disposed inside the first photoelectric conversion circuit 20-1, and the first photoelectric conversion circuit 20-1 is disposed inside the first power unit 401A. In practical applications, the relative positions of the isolation device, the photoelectric conversion circuit, and the power unit can be set according to requirements.

[0104] In some embodiments, the isolation device includes at least one of an optical isolator (e.g., an optocoupler), a magnetic coupling isolator, and a capacitive isolator. This invention does not limit the specific type of isolation device in each isolation device group; in practical applications, the type can be selected according to requirements. For example, if there is an unstable potential difference between two adjacent power units, and the higher the output voltage, the greater the potential difference, the selection of the isolation device can be determined based on the device's withstand voltage level and insulation distance. As another example, if the power unit's output is a rapidly changing PWM wave with a voltage change rate of several kilovolts per microsecond or even higher (dv / dt), the selection of the isolation device can also be based on the actual IGBT's dv / dt, choosing a device with the required common-mode withstand capability. Furthermore, magnetic coupling isolators and capacitive isolators offer better cost-effectiveness in high-speed communication and do not exhibit optical decay (decreasing optical power over time) effects; therefore, magnetic coupling isolators and / or capacitive isolators can be preferably used.

[0105] In some embodiments, each power unit has an independent communication address or location number (e.g., similar to a Modbus slave address, but not limited to, and can be customized). The master controller can communicate with the power units based on the communication address or location number and a proprietary protocol. Power units can communicate with each other based on a proprietary protocol. Communication based on independent communication addresses and / or proprietary protocols ensures secure and reliable communication between the master controller and power units, and between power units.

[0106] It should be noted that, Figures 1-9 The embodiment described herein uses an example of each power unit group comprising two power units to illustrate the inverter of the present invention. However, the present invention is not limited thereto, and each power unit group may include three, four, five, six, or more power units. The specific number of power units can be set according to requirements. Furthermore, it should be emphasized that, in the example comprising only two power units, the first power unit can be understood as the initial power unit, and the second power unit can be understood as the final power unit.

[0107] Figure 15 A schematic diagram of a modular series frequency converter 3000 according to other embodiments of the present invention is shown. Figure 15As shown, power unit group 40A includes X power units, which are connected in series. Power unit group 40B includes Y power units, which are connected in series. Power unit group 40C includes Z power units, which are connected in series. X, Y, and Z are positive integers greater than 2. Each power unit includes a controller. In the same power unit group, adjacent power units are connected through isolation devices. In different power unit groups, the first power unit (e.g., 401A) communicates with the main controller 10 through the first photoelectric conversion circuit 20-1 and the first optical fiber F. The number of power units in different power unit groups can be the same or different. It can be understood that for a power unit group including more than 3 power units, the Xth power unit, the Yth power unit, and the Zth power unit are the end power units.

[0108] Although not shown in the diagram, the terminal power units (Xth power unit, Yth power unit, and Zth power unit) in each power unit group can be connected to the second photoelectric conversion circuit. The terminal power units can be connected to the second photoelectric conversion circuit with or without isolation devices. The second photoelectric conversion circuit can be connected to the main controller via a second optical fiber. Figure 8 and Figure 9 Similar examples will not be repeated here.

[0109] like Figure 15 As shown, the main controller 10 can send control signals (e.g., optical control signals containing three-phase PWM information). These control signals are sent to the first photoelectric conversion circuit 20-1 via the first optical fiber F. The first photoelectric conversion circuit 20-1 performs photoelectric conversion on the control signal and then sends the converted control signal to the first isolation device 3011 of each isolation device group.

[0110] In some embodiments, such as Figure 15As shown, the first isolator 3011 of each isolation device group receives the control signal from the first photoelectric conversion circuit 20-1 and can send it to the first power unit (first controller) of the corresponding power unit group. For example, for power unit group 40A, the first isolator 3011 sends the control signal to the first power unit 401A. For power unit group 40B, the first isolator 3011 sends the control signal to the first power unit 401B. For power unit group 40C, the first isolator 3011 sends the control signal to the first power unit 401C. Furthermore, the first isolator 3011 can send the control signal to the second isolator 3012, which can receive the control signal and send it to the second power unit 402A and the third isolator 3013. Examples of sending the control signal to other power units (or other controllers) are similar and will not be repeated here. In other words, the control signal converted by the first photoelectric conversion circuit can be directly sent to each power unit through the isolation devices without needing to be forwarded through each power unit, as described above. Figure 4 The implementation examples are similar.

[0111] In other embodiments, the control signal converted by the first photoelectric conversion circuit can be sent to the first power unit through an isolation device. The first power unit then forwards the signal to the second power unit via the isolation device, and the second power unit receives the signal and forwards it to the third power unit via the isolation device, and so on. That is, the control signal converted by the first photoelectric conversion circuit can be forwarded (processed or not processed) to each power unit through the power units in a step-by-step manner, as described above. Figure 5 The implementation examples are similar and will not be described again here.

[0112] In some embodiments, such as Figure 15 As shown, the fifth power unit 405A includes a fifth controller C5. The fifth controller C5 can determine its own status information and send it to the fourth power unit 404A (fourth controller C4) via an isolation device. The fourth power unit 404A can determine its own status information, receive the status information of the fifth power unit 405A, and forward the status information of the fourth power unit 404A and / or the status information of the fifth power unit 405A to the third power unit 403A (third controller C3) via an isolation device.

[0113] The third power unit 403A can determine its own status information, and can also receive the status information of the fourth power unit 404A and / or the fifth power unit 405A. It can also forward the status information of at least one of the third power unit 403A, the fourth power unit 404A or the fifth power unit 405A to the second power unit 402A through an isolation device.

[0114] And so on. This continues until the first power unit sends its own and / or other power unit's status information to the first photoelectric conversion circuit and / or the second photoelectric conversion circuit. After photoelectric conversion, the information is transmitted to the main controller via optical fiber. In other words, each power unit's controller can determine its own status information, receive status information from other power units, and also send its own and / or other power unit's status information to other power units. In other words, each power unit's status information can be forwarded (processed or not processed) cascaded through other power units to the photoelectric conversion circuit. (As mentioned above...) Figure 6 or Figure 8 Similar examples will not be repeated here.

[0115] In other embodiments, after the controller of each power unit determines its own state information, it can directly send it to the first photoelectric conversion circuit and / or the second photoelectric conversion circuit through an isolation device. The first and / or second photoelectric conversion circuits then perform photoelectric conversion and send the information via optical fiber to the main controller, without needing to forward it through other power units step by step, as described above. Figure 7 or Figure 9 Similar examples will not be repeated here.

[0116] In some embodiments, the first optical fiber F and the second optical fiber F' can be unidirectional optical fibers or bidirectional optical fibers.

[0117] Figure 16 A schematic diagram of a modular series frequency converter 4000 according to other embodiments of the present invention is shown. Figure 16 As shown, the modular series inverter 4000 includes three first photoelectric conversion circuits 20-1, each of which is disposed inside the first power units 401A to 401C in each power unit group. It should be understood that each first photoelectric conversion circuit 20-1 can also be disposed outside the first power units 401A to 401C in each power unit group. Each first photoelectric conversion circuit 20-1 is connected to the main controller 10 via a first optical fiber F, which can be a bidirectional optical fiber.

[0118] In some embodiments, the modular series inverter of the present invention can be a modular series high voltage inverter.

[0119] In some embodiments, the modular series inverter of the present invention may further include devices or circuits such as amplifiers, housings, rectifiers, and motors.

[0120] The present invention also provides a frequency converter system. Figure 17 A schematic diagram of a frequency converter system 5000 according to some embodiments of the present invention is shown. Figure 17As shown, the inverter system 5000 includes the modular series inverters 1000 / 2000 / 3000 / 4000 as described above.

[0121] In some embodiments, the inverter system 5000 may include one or more modular series inverters 1000 / 2000 / 3000 / 4000 ( Figure 17 An example is shown of a modular series frequency converter.

[0122] In some embodiments, the inverter system 5000 may further include a main controller (not shown). The main controller may be coupled to the modular series inverters 100 / 200 to control the operation of the modular series inverters 1000 / 2000 / 3000 / 4000.

[0123] The frequency converter system of the present invention, by adopting the above-mentioned modular series frequency converter, can significantly reduce the use of optical fibers and optical fiber transceivers, reduce costs, and reduce communication failures caused by optical fibers (e.g., plastic optical fibers) in humid, corrosive, and high-dust environments, thereby improving the communication quality and reliability of the frequency converter system.

[0124] The present invention also provides a method for operating a modular series frequency converter. Figure 18 A flowchart illustrating a method 6000 for operating a modular series frequency converter according to some embodiments of the present invention is shown. Figure 18 As shown, the working method 6000 includes steps S610 to S650.

[0125] In step S610, a control signal is sent through the main controller of the module series inverter.

[0126] In step S620, the control signal is sent to the first photoelectric conversion circuit through the first optical fiber.

[0127] In step S630, the control signal is photoelectrically converted by the first photoelectric conversion circuit.

[0128] In step S640, the control signal after photoelectric conversion is sent to the first power unit of the three power unit groups respectively.

[0129] In step S650, the control signal is sent to the second power unit of the three power unit groups through the isolation devices in the three isolation device groups respectively.

[0130] In some embodiments, each isolation device group includes multiple isolation devices, and the multiple isolation devices include at least a first isolation device and a second isolation device. The first power unit is connected to the first photoelectric conversion circuit through the first isolation device. The operating method 6000 further includes: sending the photoelectric converted control signal to the first isolation device of each of the three isolation device groups.

[0131] In some embodiments, the first power unit includes a first controller, the second power unit includes a second controller, and the operating method 6000 further includes: receiving a converted control signal from a first photoelectric conversion circuit through a first isolation device, and sending the converted control signal to the first controller and the second isolation device; receiving the converted control signal from the first isolation device through the first controller; and receiving the converted control signal from the second isolation device through the second controller.

[0132] In some embodiments, the first power unit includes a first controller, the second power unit includes a second controller, and the operating method 6000 further includes: receiving a converted control signal from a first photoelectric conversion circuit through a first isolation device, and sending the converted control signal to the first controller; receiving the converted control signal from the first isolation device through the first controller, and sending the converted control signal to the second isolation device; and receiving the converted control signal from the second isolation device through the second controller.

[0133] In some embodiments, each isolation device group further includes a third isolation device and a fourth isolation device, wherein the third isolation device connects the second power unit and the first power unit, and the fourth isolation device connects the first power unit and the first photoelectric conversion circuit.

[0134] In some embodiments, the operating method 6000 further includes: determining the status information of the second power unit through the second controller and sending the status information of the second power unit to the third isolation device; receiving the status information of the second power unit through the third isolation device and sending the status information of the second power unit to the first controller; receiving the status information of the second power unit through the first controller and sending the status information of the second power unit to the fourth isolation device.

[0135] In some embodiments, the operating method 6000 further includes: determining the status information of the second power unit through the second controller and sending the status information of the second power unit to the third isolation device; receiving the status information of the second power unit through the third isolation device and sending the status information of the second power unit to the fourth isolation device.

[0136] In some embodiments, the operating method 6000 further includes: determining the status information of the first power unit through the first controller, and sending the status information of the first power unit to the fourth isolation device.

[0137] In some embodiments, the operating method 6000 further includes: receiving status information of the first power unit and / or the second power unit through a fourth isolation device, and sending the status information of the first power unit and / or the second power unit to a first photoelectric conversion circuit; receiving the status information of the first power unit and / or the second power unit from the fourth isolation device through the first photoelectric conversion circuit, and sending it to the main controller via a first optical fiber after photoelectric conversion.

[0138] In some embodiments, the modular series inverter further includes a second photoelectric conversion circuit, which is connected to the second power unit and the main controller.

[0139] In some embodiments, the operating method 6000 further includes: determining the status information of the first power unit through the first controller and sending the status information of the first power unit to the second isolation device; receiving the status information of the first power unit through the second isolation device and sending the status information of the first power unit to the second controller; receiving the status information of the first power unit through the second controller and sending the status information of the first power unit to the second photoelectric conversion circuit.

[0140] In some embodiments, the operating method 6000 further includes: determining the status information of the first power unit through the first controller and sending the status information of the first power unit to the second isolation device; receiving the status information of the first power unit through the second isolation device and sending the status information of the first power unit to the second photoelectric conversion circuit.

[0141] In some embodiments, the operating method 6000 further includes: determining the status information of the second power unit through the second controller, and sending the status information of the second power unit to the second photoelectric conversion circuit.

[0142] In some embodiments, each isolation device group further includes: a fifth isolation device, the fifth isolation device connecting the second power unit and the second photoelectric conversion circuit, the second photoelectric conversion circuit being connected to the main controller via a second optical fiber; the operating method 6000 further includes: sending the status information of the first power unit and / or the second power unit to the second photoelectric conversion circuit via the fifth isolation device; receiving the status information of the first power unit and / or the second power unit via the second photoelectric conversion circuit, performing photoelectric conversion on it, and then sending it to the main controller via the second optical fiber.

[0143] In some embodiments, each power unit has an independent communication address, and the operating method 6000 further includes: the main controller communicating with the power units based on the communication address and a private protocol; and the power units communicating with each other based on a private protocol.

[0144] The operating method 6000 of the modular series inverter of the present invention can be implemented by the above-mentioned modular series inverters 1000 / 2000 / 3000 / 4000, which can significantly reduce the use of optical fibers and optical fiber transceivers, reduce costs, and improve communication quality and reliability.

[0145] The present invention also provides a computer-readable storage medium including computer-executable instructions stored thereon, which, when executed by a processor, implement the operation method 6000 as described above.

[0146] In some embodiments, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used or combined with an instruction execution system, apparatus, or device. Computer-readable storage media include, but are not limited to, electrical, magnetic, optical, or semiconductor forms or devices, and more specific examples (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer hard disk, a hard disk drive, random access memory (RAM), non-volatile random access memory (NVRAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0147] It should be noted that this specification provides method operation steps as shown in the embodiments or diagrams, but based on conventional or non-inventive labor, more or fewer operation steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many steps and does not represent the only execution order. In actual system or device products, the methods shown in the embodiments or flowcharts can be executed sequentially or in parallel.

[0148] It should be noted that any embodiment or combination thereof of the modular series inverter, the working method of the modular series inverter, the inverter system and the computer-readable storage medium of the present invention can be applied to each other, and all of these are within the protection scope of the present invention.

[0149] In some embodiments, the main controller, the controllers in each power unit, and the overall controller in the inverter system may include a central processing unit (CPU), a microcontroller unit (MCU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and similar devices.

[0150] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A modular cascaded frequency converter, comprising: a master controller; an optical-electrical conversion circuit comprising a first optical-electrical conversion circuit, the first optical-electrical conversion circuit being communicatively connected to the master controller via a first optical fiber; three groups of power units, each group of power units comprising a plurality of power units, the plurality of power units comprising at least a first power unit and a second power unit, wherein the first power unit is connected to the first optical-electrical conversion circuit; and three groups of isolation devices, each group of isolation devices comprising one or more isolation devices; wherein the groups of power units and the groups of isolation devices correspond to each other, and in each group of power units, the first power unit is communicatively connected to the second power unit via the isolation devices. 2.The modular cascaded frequency converter of claim 1, wherein each group of isolation devices comprises a plurality of isolation devices, the plurality of isolation devices comprising at least a first isolation device and a second isolation device, the first power unit being connected to the first optical-electrical conversion circuit via the first isolation device. 3.The modular cascaded frequency converter of claim 2, wherein the master controller is configured to send a control signal to the first optical-electrical conversion circuit via the first optical fiber, the first optical-electrical conversion circuit being configured to optically-electrically convert the control signal and send the converted control signal to the first isolation device. 4.The modular cascaded frequency converter of claim 3, wherein the first power unit comprises a first controller, the second power unit comprises a second controller, the first isolation device is configured to receive the converted control signal from the first optical-electrical conversion circuit and send the converted control signal to the first controller and the second isolation device, the first controller is configured to receive the converted control signal from the first isolation device, and the second controller is configured to receive the converted control signal from the second isolation device. 5.The modular cascaded frequency converter of claim 3, wherein the first power unit comprises a first controller, the second power unit comprises a second controller, the first isolation device is configured to receive the converted control signal from the first optical-electrical conversion circuit and send the converted control signal to the first controller, the first controller is configured to receive the converted control signal from the first isolation device and send the converted control signal to the second isolation device, and the second controller is configured to receive the converted control signal from the second isolation device. 6.The modular cascaded frequency converter of any one of claims 2-5, wherein each group of isolation devices further comprises a third isolation device and a fourth isolation device, wherein the third isolation device connects the second power unit to the first power unit, and the fourth isolation device connects the first power unit to the first optical-electrical conversion circuit.

7. The modular cascaded frequency converter of claim 6, wherein the second controller is configured to determine status information of the second power unit and send the status information of the second power unit to the third isolation device; the third isolation device is configured to receive the status information of the second power unit and send the status information of the second power unit to the first controller; and the first controller is configured to receive the status information of the second power unit and send the status information of the second power unit to the fourth isolation device.

8. The modular cascaded frequency converter of claim 6, wherein the second controller is configured to determine status information of the second power unit and send the status information of the second power unit to the third isolation device; the third isolation device is configured to receive the status information of the second power unit and send the status information of the second power unit to the fourth isolation device.

9. The modular cascaded frequency converter of claim 6, wherein the first controller is further configured to determine status information of the first power unit and send the status information of the first power unit to the fourth isolation device.

10. The modular cascaded frequency converter of claim 6, wherein the fourth isolation device is configured to receive status information of the first and / or second power units and send the status information of the first and / or second power units to the first opto-electric conversion circuit; and the first opto-electric conversion circuit is configured to receive the status information of the first and / or second power units from the fourth isolation device and send it to the main controller via the first optical fiber after opto-electric conversion.

11. The modular cascaded frequency converter of any of claims 2-5, wherein the opto-electronic conversion circuit further comprises: a second opto-electric conversion circuit connecting the second power unit and the main controller.

12. The modular cascaded frequency converter of claim 11, wherein the first controller is configured to determine status information of the first power unit and send the status information of the first power unit to the second isolation device; the second isolation device is configured to receive the status information of the first power unit and send the status information of the first power unit to the second controller; and the second controller is configured to receive the status information of the first power unit and send the status information of the first power unit to the second opto-electric conversion circuit.

13. The modular cascaded frequency converter of claim 11, wherein the first controller is configured to determine status information of the first power unit and send the status information of the first power unit to the second isolation device; the second isolation device is configured to receive the status information of the first power unit and send the status information of the first power unit to the second opto-electric conversion circuit.

14. The modular cascaded frequency converter of claim 11, wherein the second controller is configured to determine status information of the second power unit and send the status information of the second power unit to the second opto-electric conversion circuit.

15. The modular series-connected frequency converter of claim 11, wherein each set of isolation devices further comprises: a fifth isolation device connecting the second power unit and the second photoelectric conversion circuit, the second photoelectric conversion circuit being connected with the main controller through a second optical fiber; the state information of the first power unit and / or the second power unit being sent to the second photoelectric conversion circuit through the fifth isolation device; the second photoelectric conversion circuit being configured to receive the state information of the first power unit and / or the second power unit, and send it to the main controller through the second optical fiber after photoelectric conversion.

16. The module series connection frequency converter according to any one of claims 1-5, wherein the photoelectric conversion circuit is arranged outside or inside the power unit; the first photoelectric conversion circuit is arranged outside or inside the first power unit.

17. The module series connection frequency converter according to claim 11, wherein the second photoelectric conversion circuit is arranged outside or inside the second power unit.

18. The module series connection frequency converter according to any one of claims 1-5, wherein the isolation device is arranged outside or inside the power unit.

19. The module series connection frequency converter according to any one of claims 1-5, wherein the isolation device is arranged outside or inside the photoelectric conversion circuit.

20. The module series connection frequency converter according to any one of claims 1-5, wherein the isolation device comprises at least one of an optical isolator, a magnetic coupling isolation device and a capacitive isolator.

21. The module series connection frequency converter according to any one of claims 1-5, wherein each power unit has an independent communication address, the main controller being configured to communicate with the power units based on the communication address and a private protocol; the power units communicate with each other based on a private protocol.

22. A frequency converter system comprising the module series connection frequency converter according to any one of claims 1-21.

23. A method for operating a module series connection frequency converter, comprising: sending a control signal by a main controller of the module series connection frequency converter; sending the control signal to a first photoelectric conversion circuit through a first optical fiber; photoelectrically converting the control signal by the first photoelectric conversion circuit; sending the converted control signal to a first power unit of a first power unit group, respectively; and sending the control signal to a second power unit of the first power unit group through an isolation device of a first isolation device group, respectively. 24.The working method according to claim 23, wherein each group of isolation devices comprises a plurality of isolation devices, the plurality of isolation devices comprising at least a first isolation device and a second isolation device, the first power unit connecting the first photoelectric conversion circuit through the first isolation device; the working method comprising: sending the photoelectrically converted control signal to a first isolation device of a second isolation device group, respectively.

25. The method for operating according to claim 24, wherein the first power unit comprises a first controller, and the second power unit comprises a second controller, the method further comprising: The first isolating device receives the converted control signal from the first photoelectric conversion circuit and sends the converted control signal to the first controller and the second isolating device; the first controller receives the converted control signal from the first isolating device; the second controller receives the converted control signal from the second isolating device; Or The first isolating device receives the converted control signal from the first photoelectric conversion circuit and sends the converted control signal to the first controller; the first controller receives the converted control signal from the first isolating device and sends the converted control signal to the second isolating device; the second controller receives the converted control signal from the second isolating device.

26. The method of Claim 25, wherein each set of isolation devices further comprises a third isolation device and a fourth isolation device, wherein the third isolation device connects the second power cell with the first power cell, and the fourth isolation device connects the first power cell with the first photoelectric conversion circuit. The working method further comprises: The second controller determines the state information of the second power unit and sends the state information of the second power unit to the third isolating device; The third isolating device receives the state information of the second power unit and sends the state information of the second power unit to the first controller; the first controller receives the state information of the second power unit and sends the state information of the second power unit to the fourth isolating device; or The second controller determines the state information of the second power unit and sends the state information of the second power unit to the third isolating device; the third isolating device receives the state information of the second power unit and sends the state information of the second power unit to the fourth isolating device.

27. The method of claim 26, further comprising: The first controller determines the state information of the first power unit and sends the state information of the first power unit to the fourth isolating device; The fourth isolating device receives the state information of the first power unit and / or the second power unit and sends the state information of the first power unit and / or the second power unit to the first photoelectric conversion circuit; the first photoelectric conversion circuit receives the state information of the first power unit and / or the second power unit from the fourth isolating device and sends it to the main controller after photoelectric conversion via the first optical fiber.

28. The method of claim 25, wherein the modular string frequency converter further comprises: A second photoelectric conversion circuit is connected between the second power unit and the main controller. The working method further comprises: The first controller determines the state information of the first power unit and sends the state information of the first power unit to the second isolating device; The second isolating device receives the state information of the first power unit and sends the state information of the first power unit to the second controller; the second controller receives the state information of the first power unit and sends the state information of the first power unit to the second photoelectric conversion circuit; or The first controller determines the state information of the first power unit and sends the state information of the first power unit to the second isolation device; the second isolation device receives the state information of the first power unit and sends the state information of the first power unit to the second photoelectric conversion circuit.

29. The method of claim 28, further comprising: The second controller determines the state information of the second power unit and sends the state information of the second power unit to the second photoelectric conversion circuit.

30. The method of working according to claim 28 or 29, wherein each group of isolation devices further comprises: A fifth isolation device is connected between the second power unit and the second photoelectric conversion circuit, and the second photoelectric conversion circuit is connected to the main controller through a second optical fiber; the working method further comprises: sending the state information of the first power unit and / or the second power unit to the second photoelectric conversion circuit through the fifth isolation device; receiving the state information of the first power unit and / or the second power unit by the second photoelectric conversion circuit, and sending it to the main controller through the second optical fiber after photoelectric conversion.

31. A computer-readable storage medium comprising computer-executable instructions stored thereon that, when executed by a processor, perform the working method of any one of claims 23-30.

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