Module tandem type frequency converter and frequency converter system

Abstract

The utility model provides a module series frequency converter and a frequency converter system. 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] The utility model generally relates to the technical field of frequency converters, and in particular to a module series frequency converter and a frequency converter system. Background Art

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

[0003] The modular series inverter is a structure in which multiple power units are connected in series. In some existing solutions, all power units are connected to the main control through optical fiber communication, or the power units are connected to each other through optical fiber communication. This connection method leads to high cost of modular series inverter, complicated wiring, and optical fiber communication is greatly affected by the environment. Communication problems are prone to occur in corrosive dust environments. How to reduce the cost of modular series inverter and improve the reliability of communication connection is the technical problem to be solved by the utility model.

[0004] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the prior art in the field. Utility Model Content

[0005] In view of one or more problems existing in the prior art, the utility model provides a modular series inverter, comprising:

[0006] Main controller;

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

[0008] three power unit groups, each power unit group includes a plurality of power units, the plurality of 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 isolation device group including one or more isolation devices;

[0010] The power unit groups correspond to the isolation device groups one by one, and in each power unit group, the first power unit is communicatively connected with the second power unit through the isolation device.

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

[0012] Optionally, the main controller is configured to send a control signal, the control signal is sent 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 with the first power unit, and the fourth isolation device connects the first power unit with the first photoelectric conversion circuit.

[0016] Optionally, 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 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 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 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 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 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 send it to the main controller via the first optical fiber after performing photoelectric conversion.

[0020] Optionally, the photoelectric conversion circuit further includes: a second photoelectric conversion circuit, wherein the second photoelectric conversion circuit connects the second power unit and the main controller.

[0021] Optionally, 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 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 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 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 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 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, which connects the second power unit and the second photoelectric conversion circuit, and the second photoelectric conversion circuit is connected to the main controller via a second optical fiber; the status information of the first power unit and / or the second power unit is sent to the second photoelectric conversion circuit via the fifth isolation device; the second photoelectric conversion circuit is configured to receive the status information of the first power unit and / or the second power unit, and send it to the main controller via the second optical fiber after performing photoelectric conversion.

[0025] Optionally, 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.

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

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

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

[0029] Optionally, the isolation device includes at least one of an optical isolator, a magnetic coupling isolation device 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 utility model also provides a frequency converter system, comprising the module series frequency converter as described above.

[0032] The modular series inverter of the utility model has power units in the same group connected by isolation devices and wires. Compared with the prior art (for example, each power unit is directly connected to the main controller by optical fiber or connected in a ring), the use of optical fiber and optical fiber transceivers can be greatly reduced, and the cost of the inverter can be effectively reduced. At the same time, communication failures caused by optical fiber (for example, plastic optical fiber) in humid, corrosive, and high-dust environments can be reduced, thereby improving the communication quality of the inverter, improving the reliability of the inverter, and improving the competitiveness of the inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 A schematic diagram of a module series inverter according to some embodiments of the present utility model is shown.

[0035] Figure 2 Schematic diagrams of module series inverters according to other embodiments of the utility model are shown.

[0036] Figure 3 A topological schematic diagram of a power unit according to some embodiments of the present invention is shown.

[0037] Figure 4 A schematic diagram showing a power unit receiving a control signal according to some embodiments of the present utility model is shown.

[0038] Figure 5 A schematic diagram showing a power unit receiving a control signal according to other embodiments of the utility model is shown.

[0039] Figures 6 to 9 A schematic diagram showing a power unit sending status information according to some embodiments of the present utility model is shown.

[0040] Fig.10 and Fig.11 A schematic diagram showing the positional relationship between a photoelectric conversion circuit and a power unit according to some embodiments of the present utility model.

[0041] Fig.12 and Fig.13 A schematic diagram showing the positional relationship between an isolation device and a photoelectric conversion circuit according to some embodiments of the present invention.

[0042] Fig.14 A schematic diagram showing the positional relationship among an isolation device, a photoelectric conversion circuit and a power unit according to some embodiments of the present utility model.

[0043] Fig.15 A schematic diagram of a module series inverter according to some further embodiments of the utility model is shown.

[0044] Fig.16 Schematic diagrams of module series inverters according to yet other embodiments of the utility model are shown.

[0045] Fig.17 A schematic diagram of a frequency converter system according to some embodiments of the present invention is shown.

[0046] Fig.18 A flow chart showing a working method of a module series inverter according to some embodiments of the present utility model. DETAILED DESCRIPTION

[0047] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0048] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "plurality" means two or more than two, unless otherwise clearly and specifically defined.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", and "coupling" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0051] Many different embodiments or examples are provided below to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0052] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0053] The utility model provides a modular series inverter. The modular series inverter includes a main controller, a photoelectric conversion circuit, three isolation device groups and three power unit groups. Among them, the photoelectric conversion circuit includes a first photoelectric conversion circuit, and the first photoelectric conversion circuit is connected to the main controller through a first optical fiber communication. In the three isolation device groups, each isolation device group includes one or more isolation devices. In the three power unit groups, each power unit group includes a plurality of power units. The plurality of 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 to the isolation device groups one by one, and in each power unit group, the first power unit is connected to the second power unit through an isolation device.

[0054] The modular series inverter of the utility model has the power units of the same group connected by isolation devices and wires. Compared with the prior art (for example, each power unit is directly connected or ring-connected to the main controller via optical fiber), the use of optical fiber and optical fiber transceiver can be greatly reduced, and the cost of the inverter can be effectively reduced. At the same time, communication failures caused by optical fiber (for example, plastic optical fiber) in a humid, corrosive, and high-dust environment can be reduced, and the communication quality of the inverter can be improved, and the reliability of the inverter can be improved, and the competitiveness of the inverter can be improved. The following is a detailed introduction.

[0055] Figure 1 FIG. 1 shows a schematic diagram of a modular series inverter 1000 according to some embodiments of the present invention. Figure 1As shown, the modular series inverter 1000 includes a main controller 10, an optoelectronic conversion circuit 20, an isolation device group 30 and a power unit group 40. The optoelectronic conversion circuit 20 includes a first optoelectronic conversion circuit 20-1, and the first optoelectronic conversion circuit 20-1 is connected to the main controller 10 through a first optical fiber F. The optoelectronic conversion circuit 20 includes, for example, an optical fiber communication transceiver, a transceiver circuit, etc. The power unit group 40 includes three power unit groups 40A, 40B, and 40C. The input of the main circuit of the power unit group 40A to 40C can be connected to the transformer output (not shown in the figure). Each power unit group includes a plurality of power units, and the plurality of power units include at least a first power unit and a second power unit. For example, the power unit group 40A includes a first power unit 401A and a second power unit 402A; the power unit group 40B includes a first power unit 401B and a second power unit 402B; and the power unit group 40C includes a first power unit 401C and a second power unit 402C. The isolation device group 30 includes one or more isolation devices 300 (one isolation device is illustrated in the figure). The power unit group corresponds to the isolation device group one by one. In each power unit group, the first power unit is connected to the second power unit 402 through the isolation device 300 (and the wire). For example, in the power unit group 40A, the first power unit 401A is connected to the second power unit 402A through the isolation device 300 (and the wire). In other words, in the same power unit group, the power units are connected to each other through the isolation device (and the wire). The power units in the same power unit group are connected through the isolation device, which can reduce the use of optical fibers and optical fiber transceivers, reduce the cost of the frequency converter, and improve the communication reliability between the power units in the same power unit group, thereby reducing the cost of the frequency converter and improving the reliability of the frequency converter.

[0056] Figure 2 FIG. 2 shows a schematic diagram of a modular series inverter 2000 according to other embodiments of the present invention. Figure 1 and 2As shown, the modular series inverter 2000 is substantially the same as the modular series inverter 1000, and the differences between the two are described below in detail. The isolation device group 30 includes a plurality of isolation devices. For example, the plurality of isolation devices include at least a first isolation device 301 and a second isolation device 302. In each power unit group, the first power unit is connected to the first photoelectric conversion circuit 20-1 through the first isolation device 301 (and a wire), and is connected to the second power unit 402 through the second isolation device 302 (and a wire). For example, in the power unit group 40A, the first power unit 401A is connected to the first photoelectric conversion circuit 20-1 through the first isolation device 301 (and a wire), and is connected to the second power unit 402A through the second isolation device 302 (and a wire). In other words, in the same power unit group, the power units are connected to each other through isolation devices (and wires), and the first power unit is connected to the first photoelectric conversion circuit through isolation devices (and wires). In this way, not only can the use of optical fiber and optical fiber transceivers be reduced, the cost of the frequency converter be reduced, and the communication reliability between power units in the same power unit group be improved, but also the communication reliability between the first power unit and the first optoelectronic conversion circuit can be improved.

[0057] In the modular series inverter of the utility model, the power units of different groups are connected only by the power units at the neutral point through the isolation device (and the wire), for example, the first power unit in each power unit group (see Figure 2 The output terminals of the same name (not shown) of the first power units 401A, 401B, and 401C in the figure are connected together to form a neutral point of the three-phase output of the inverter, which is beneficial to the stable operation of the inverter and improves the reliability of the inverter.

[0058] Figure 3 FIG. 2 shows a topological schematic diagram of a power unit according to some embodiments of the present utility model. Figure 3 As shown, the rectifier side of the power unit uses diodes (e.g., D1-D6) for three-phase (R, S, T) full-wave rectification; capacitors (e.g., C1-Cn, n is a positive integer) are used in the middle for filtering and energy storage; the output side uses an inverter bridge composed of insulated gate bipolar transistors (e.g., IGBT1-IGBT4), which can convert DC input into AC output, for example, a single-phase equal-amplitude AC PWM waveform output voltage can be provided. The inverter bridge can be an H-bridge or a three-level H-bridge, etc. The rectifier side input of the power unit can include a protection circuit, such as Figure 3 The fuses Fuse1 and Fuse2 shown in the embodiment of the present invention are shown in the embodiment of the present invention. It should be noted that the devices inside the power unit are not limited to Figure 3As shown in the embodiments, other components may also be included, and the number of components and their connection relationships may be adjusted according to actual conditions, all of which are within the protection scope of the present utility model.

[0059] In some embodiments, each power unit may include a controller. For convenience, the power unit group 40A is used as an example for description below. It should be understood that the examples of the power unit group 40B and the power unit group 40C are the same or similar to the example of the power unit group 40A.

[0060] Figure 4 FIG. 2 shows a schematic diagram of a power unit receiving a control signal according to some embodiments of the present utility model. 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 a control signal (for example, an optical control signal containing three-phase PWM information). The control signal is 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.

[0061] In some embodiments, 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. In other words, 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 through the first controller (first power unit). In other words, the control signal converted by the first photoelectric conversion circuit can be sent to each power unit in parallel through the isolation device without the need for the power unit to forward step by step, thereby ensuring the communication rate and real-time performance between the main controller and the power unit, and between the power units.

[0062] In other embodiments, Figure 5As shown, the first isolation device 301 receives a 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. In other words, 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) to each power unit step by step through the power unit, and can be forwarded directly, or it can be forwarded after processing (such as inserting the status information of its own power unit), which ensures the communication flexibility between power units.

[0063] In some embodiments, 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) and the first power unit (e.g., 401A). The fourth isolation device 304 connects the first power unit (e.g., 401A) and the first photoelectric conversion circuit 20-1. Preferably, the isolation device may also include a device such as an amplifier (e.g., Figure 2 The amplifier is connected to the isolation device, which can be integrated inside the isolation device or arranged outside the isolation device. In practical applications, it can be arranged according to requirements.

[0064] In some embodiments, 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, and sends the status information of the second power unit 402A to the main controller 10 via the first optical fiber F after performing photoelectric conversion. In other words, 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, the power unit may first send its own status information to other power units step by step, which are then received and forwarded (processed or not) to the photoelectric conversion circuit by other power units.

[0065] In other embodiments, Figure 7 As shown, the second controller C2 determines the state information of the second power unit 402A, and sends the state information of the second power unit 402A to the third isolation device 303. The third isolation device 303 receives the state information of the second power unit 402A, and sends the state information of the second power unit 402A to the fourth isolation device 304. The fourth isolation device 304 receives the state information of the second power unit 402A, and sends the state information of the second power unit 402A to the first photoelectric conversion circuit 20-1. The first photoelectric conversion circuit 20-1 receives the state information of the second power unit 402A from the fourth isolation device 304, and sends the state information of the second power unit 402A to the main controller 10 via the first optical fiber F after performing photoelectric conversion. In other words, the state information of the second power unit can be sent directly 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 state information to the photoelectric conversion circuit in parallel through the isolation device, without the need for the power unit to forward step by step, thereby ensuring the communication rate and real-time performance.

[0066] It should be noted that, refer to Figure 7, the output signals of the first controller C1 and the isolation device 303 are simultaneously connected to the input end (for example, input pin, not shown in the figure) of the fourth isolation device 304. Considering the potential signal conflict, preferably, the modular series inverter of this embodiment may include a switching circuit (not shown in the figure), and the switching circuit may be connected between two output ends and one input end to resolve the high and low level conflicts and / or task priority conflicts of the two output ends. The switching circuit may include an open collector gate (OC), an open drain gate (OD) or a similar circuit. The switching circuit may be set separately from the isolation device and the controller, or may be integrated inside the isolation device, or integrated inside the controller, and may be set according to requirements.

[0067] For example, refer to Figure 7 , the input end of the switch circuit (not shown) can be connected to the output end of the first controller C1 and the third isolation device 303, and the output end of the switch circuit is connected to the input end of the fourth isolation device 304. The switch circuit can solve the high-low level conflict and / or task priority conflict of the output signals of the first controller C1 and the third isolation device 303 by high-low level conversion. For example, the first controller C1 outputs a high level, and the third isolation device 303 outputs a low level, and there is a high-low level conflict between the output signals of the two. The switch circuit (for example, an OC gate circuit) can convert the high-level input (from the first controller C1) into a low-level output to solve the high-low level conflict problem. The first controller C1 can continuously monitor the output level of the switch circuit. When it is determined that the switch circuit outputs a low level, the first controller C1 suspends sending data, and the third isolation device 303 preferentially sends data to the fourth isolation device 304. After the third isolation device finishes sending data, the output level of the switch circuit becomes a high level. At this time, the first controller C1 sends data to the fourth isolation device 304 again, thereby solving the task priority conflict. That is to say, the switch circuit (e.g., OC gate circuit) can resolve the level conflict by converting the high level input into the low level output. It should be understood that the switch circuit (e.g., OD gate circuit) can also convert the low level input into the high level output to resolve the level conflict. The first controller can solve the task conflict by suspending the transmission of data when monitoring the switch circuit outputting the low level, and sending the data when monitoring the switch circuit outputting the high level. The task priority can be set according to the status information of the power unit (how to determine the status information of the power unit will be described later), depending on the actual situation.

[0068] In short, the switching circuit can resolve level conflicts by converting 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 output level of the controller itself, the controller can send data; when the output level of the switching circuit does not match its own output level, the controller can suspend sending data and give priority to other tasks, so that the modular series inverter has conflict detection and conflict resolution functions, thereby achieving stable and reliable operation and improving the robustness of the modular series inverter.

[0069] The modular series inverter of the utility model adopts a communication mechanism similar to IIC. The controller of the power unit can include both a signal input terminal and a signal output terminal, and the signal input terminal and the signal output terminal can be combined into one. The power unit can realize conflict detection and conflict resolution functions through the controller and the switch circuit.

[0070] In some embodiments, Figure 6 and Figure 7 As shown, the first controller C1 determines the state information of the first power unit 401A, and sends the state information of the first power unit 401A to the fourth isolation device 304. The fourth isolation device 304 receives the state information of the first power unit 401A, and sends the state information of the first power unit 401A to the first photoelectric conversion circuit 20-1. The first photoelectric conversion circuit 20-1 receives the state information of the first power unit 401A from the fourth isolation device 304, and sends the state information of the first power unit 401A to the main controller 10 via the first optical fiber F.

[0071] 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 send it to the main controller 10 via the first optical fiber F after performing photoelectric conversion.

[0072] In some embodiments, Figure 8 As shown, the photoelectric conversion circuit further includes a second photoelectric conversion circuit 20-2. The second photoelectric conversion circuit 20-2 connects the second power unit 402A and the main controller 10. The second photoelectric conversion circuit 20-2 and the main controller 10 are connected via a second optical fiber F'.

[0073] In some embodiments, 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, and sends it to the main controller 10 via the second optical fiber F' after performing photoelectric conversion. In other words, 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, the power unit may first send its own status information to other power units step by step, which are then received and forwarded (processed or not) to the photoelectric conversion circuit by other power units.

[0074] In some embodiments, Fig. 9 As shown, the first controller C1 can determine the state information of the first power unit 401A, and send the state information of the first power unit 401A to the second isolation device 302. The second isolation device 302 can receive the state information of the first power unit 401A, and send the state information of the first power unit 401A to the second photoelectric conversion circuit 20-2. The second controller C2 can determine the state information of the second power unit 402A, and send the state information of the second power unit 402A to the second photoelectric conversion circuit 20-2. The second photoelectric conversion circuit 20-2 receives the state information of the first power unit 401A and / or the second power unit 402A, and sends it to the main controller 10 via the second optical fiber F' after performing photoelectric conversion. In other words, the state information of the first power unit can be sent directly 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 state information to the photoelectric conversion circuit in parallel through the isolation device, without the need for the power unit to forward step by step, thereby ensuring the communication rate and real-time performance.

[0075] In some embodiments, Figure 8 and Fig. 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 switch circuit can also be included between the output ends of both the second controller C2 and the second isolation device 302 and the input end of the fifth isolation device 305 to resolve high and low level conflicts and / or task priority conflicts, which is similar to the situation described in the aforementioned embodiment and will not be repeated here.

[0076] In some embodiments, the power unit may include a detection circuit (not shown) for detecting status information of the power unit. The detection circuit may be coupled to the controller, or may be integrated into the controller. The power unit and the detection circuit may correspond one to one, or multiple power units may share one detection circuit, which may be set according to requirements in practical applications.

[0077] In some embodiments, the detection circuit may include temperature, humidity, voltage, overcurrent, overheating, undervoltage, phase loss and other detection circuits. The detection circuit can detect the temperature, humidity, input side voltage, current, phase and other information of the power unit, and send the detection results to the controller. The controller can receive the detection results sent by the detection circuit, determine the status information of the power unit based on the detected information and the preset threshold, and determine whether the operating status of the power unit is normal. Preferably, different thresholds can also be set to determine the abnormal level of the operating status of the power unit, and determine the task priority of the power unit based on the abnormal level.

[0078] After the controller determines the status information of the power unit, it can Figures 6 to 9 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, control the power unit with normal operation to continue working, control the power unit with abnormal operation to stop working, etc.

[0079] In some embodiments, the photoelectric conversion circuit can be arranged outside or inside the power unit. Figure 1 , Figure 2 , Figures 4 to 7 and Fig.15 As shown, the first photoelectric conversion circuit 20-1 is arranged outside the first power unit 401A. Fig.10 and Fig.16 As shown, the first photoelectric conversion circuit 20 - 1 is disposed inside the first power unit 401A.

[0080] In some embodiments, the second photoelectric conversion circuit can be arranged outside or inside the second power unit. Figure 8 and Fig. 9 As shown, the second photoelectric conversion circuit 20-2 is arranged outside the second power unit 402A. Fig.11 As shown, the second photoelectric conversion circuit 20-2 is disposed 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.

[0081] In some embodiments, the isolation device can be disposed outside or inside the power unit. Figure 1 , Figure 2 , Figures 4 to 9 As shown, the isolation device 300 is arranged outside the first power unit 401A and the second power unit 402A; the first isolation device 301 and the fourth isolation device 304 are arranged inside the first power unit 401A; the second isolation device 302 and the third isolation device 303 are arranged inside the second power unit 402A; the fifth isolation device 305 is arranged outside the first power unit 401A and the second power unit 402A. In practical applications, the position of the isolation device relative to the power unit can be set according to requirements.

[0082] In some embodiments, the isolation device can be disposed outside or inside the photoelectric conversion circuit. Figure 1 , Figure 2 , Figures 4 to 7 As shown, the isolation device 300, the first isolation device 301, the second isolation device 302, the third isolation device 303 and the fourth isolation device 304 are arranged outside the first photoelectric conversion circuit 20-1. Figure 8 and Fig. 9 As shown, the fifth isolation device 305 is disposed outside the second photoelectric conversion circuit 20-2. Fig.12 As shown, the first isolation device 301 is disposed inside the first photoelectric conversion circuit 20-1. Fig.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.

[0083] In some embodiments, the isolation device can be arranged outside or inside the photoelectric conversion circuit, and the photoelectric conversion circuit can be arranged outside or inside the power unit. Fig.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 as required.

[0084] In some embodiments, the isolation device includes at least one of an optical isolator (e.g., an optocoupler), a magnetic coupling isolation device, and a capacitive isolator. The utility model does not limit the specific type of isolation devices in each isolation device group, and in practical applications, it can be selected according to demand. For example, there is an unstable potential difference between two adjacent power units, and the higher the output voltage, the higher the potential difference. The selection of the isolation device can be determined according to the withstand voltage level and insulation distance of the device. For another example, the output of the power unit is a fast-changing PWM wave, which has an output voltage change rate dv / dt of several thousand volts per microsecond or even higher. The selection of the isolation device can also select a device with common-mode tolerance that meets the requirements according to the dv / dt of the actual IGBT. For another example, magnetic coupling isolation devices and capacitive isolators have better cost-effectiveness in high-speed communication, and there is no light decay (light power decreases over time) effect. Magnetic coupling isolation devices and / or capacitive isolators can be preferably used.

[0085] In some embodiments, each power unit has an independent communication address or position number (for example, similar to a Modbus communication slave address, but not limited thereto, and can be customized). The main controller can communicate with the power unit based on the communication address or position number and a private protocol. The power units can communicate with each other based on a private protocol. Based on independent communication addresses and / or private protocol communication, the communication between the main controller and the power unit, and between the power units is safe and reliable.

[0086] It should be noted that Figures 1 to 9 The embodiment of the utility model is introduced by taking the example that each power unit group includes two power units. However, the utility model is not limited to this, 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. In addition, it should be emphasized that for the example including only two power units, the first power unit can be understood as the head end power unit, and the second power unit can be understood as the end power unit.

[0087] Fig.15 FIG. 2 shows a schematic diagram of a modular series inverter 3000 according to other embodiments of the present invention. Fig.15As shown, power unit group 40A includes X power units, and X power units are connected in series. Power unit group 40B includes Y power units, and Y power units are connected in series. Power unit group 40C includes Z power units, and Z power units 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 by isolation devices. In different power unit groups, the first power unit (for example, 401A) and the main controller 10 are connected to the main controller 10 through the first photoelectric conversion circuit 20-1 and the first optical fiber F. In different power unit groups, the number of power units 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, respectively.

[0088] Although not shown in the figure, the terminal power unit (Xth power unit, Yth power unit, Zth power unit) in each power unit group can be connected to the second photoelectric conversion circuit. The terminal power unit can be connected to the second photoelectric conversion circuit through an isolation device or not through an isolation device. The second photoelectric conversion circuit can be connected to the main controller via a second optical fiber. Figure 8 and Fig. 9 The example is similar to that of , so I will not repeat it here.

[0089] like Fig.15 As shown, the main controller 10 can send a control signal (for example, an optical control signal containing three-phase PWM information). The control signal is sent to the first photoelectric conversion circuit 20-1 via the first optical fiber F. After the first photoelectric conversion circuit 20-1 performs photoelectric conversion on the control signal, the converted control signal is sent to the first isolation device 3011 of each isolation device group.

[0090] In some embodiments, Fig.15As shown, the first isolation device 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 isolation device 3011 sends the control signal to the first power unit 401A. For power unit group 40B, the first isolation device 3011 sends the control signal to the first power unit 401B. For power unit group 40C, the first isolation device 3011 sends the control signal to the first power unit 401C. In addition, the first isolation device 3011 can send the control signal to the second isolation device 3012, and the second isolation device 3012 can receive the control signal and send the control signal to the second power unit 402A and the third isolation device 3013. The example of sending the control signal to other power units (or other controllers) is similar to this and will not be repeated here. That is to say, the control signal converted by the first photoelectric conversion circuit can be directly sent to each power unit through the isolation device without being forwarded step by step through the power unit, which is similar to the aforementioned Figure 4 The embodiment is similar.

[0091] In other embodiments, the control signal converted by the first photoelectric conversion circuit can be sent to the first power unit through the isolation device, forwarded by the first power unit to the second power unit through the isolation device, and then received by the second power unit and forwarded to the third power unit through the isolation device, and so on. That is to say, the control signal converted by the first photoelectric conversion circuit can be forwarded (processed or not) to each power unit step by step through the power unit, which is similar to the above Figure 5 The embodiments are similar and will not be described again here.

[0092] In some embodiments, Fig.15 As shown, the fifth power unit 405A includes a fifth controller C5, and the fifth controller C5 can determine its own state information and send it to the fourth power unit 404A (fourth controller C4) via the isolation device. The fourth power unit 404A can determine its own state information, and can also receive the state information of the fifth power unit 405A, and can also forward the state information of the fourth power unit 404A and / or the state information of the fifth power unit 405A to the third power unit 403A (third controller C3) via the isolation device.

[0093] The third power unit 403A can determine its own status information, receive status information of the fourth power unit 404A and / or status information of the fifth power unit 405A, and 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 via the isolation device.

[0094] And so on. Until the first power unit sends the status information of itself and / or other power units to the first photoelectric conversion circuit and / or the second photoelectric conversion circuit, and after photoelectric conversion, it is sent to the main controller via the optical fiber. In other words, the controller of each power unit can determine its own status information, receive the status information of other power units, and send the status information of itself and / or other power units to other power units. In other words, the status information of each power unit can be forwarded (processed or not) to the photoelectric conversion circuit step by step through other power units. Figure 6 or Figure 8 The example is similar and will not be repeated here.

[0095] In other embodiments, after the controller of each power unit determines its own status information, it can be directly sent to the first photoelectric conversion circuit and / or the second photoelectric conversion circuit through the isolation device, and the first photoelectric conversion circuit and / or the second photoelectric conversion circuit perform photoelectric conversion and then send it to the main controller via the optical fiber without being forwarded step by step through other power units, which is similar to the above Figure 7 or Fig. 9 The example is similar and will not be repeated here.

[0096] In some embodiments, the first optical fiber F and the second optical fiber F' may be unidirectional optical fibers or bidirectional optical fibers.

[0097] Fig.16 FIG. 4 shows a schematic diagram of a modular series inverter 4000 according to other embodiments of the present invention. Fig.16 As shown, the modular series inverter 4000 includes three first photoelectric conversion circuits 20-1, each of which is respectively arranged inside the first power unit 401A-401C in each power unit group. It should be understood that each first photoelectric conversion circuit 20-1 can also be arranged outside the first power unit 401A-401C in each power unit group. Each first photoelectric conversion circuit 20-1 is connected to the main controller 10 through a first optical fiber F, and the first optical fiber F can be a bidirectional optical fiber.

[0098] In some embodiments, the modular series inverter of the present invention may be a modular series high-voltage inverter.

[0099] In some embodiments, the modular series inverter of the present invention may also include devices or circuits such as an amplifier, a housing, a rectifier, and a motor.

[0100] The utility model also provides a frequency converter system. Fig.17 FIG. 5 shows a schematic diagram of a frequency converter system 5000 according to some embodiments of the present invention. Fig.17As shown, the inverter system 5000 includes the modular series inverter 1000 / 2000 / 3000 / 4000 as described above.

[0101] In some embodiments, the inverter system 5000 may include one or more modular series inverters 1000 / 2000 / 3000 / 4000 ( Fig.17 A modular series frequency converter is shown as an example.

[0102] In some embodiments, the inverter system 5000 may further include a master controller (not shown). The master controller may be coupled to the modular series inverter 100 / 200 to control the operation of the modular series inverter 1000 / 2000 / 3000 / 4000.

[0103] The inverter system of the utility model can significantly reduce the use of optical fibers and optical fiber transceivers by adopting the above-mentioned module series inverter, can reduce costs, and can reduce communication failures caused by optical fibers (for example, plastic optical fibers) in humid, corrosive, and high-dust environments, thereby improving the communication quality and reliability of the inverter system.

[0104] The utility model also provides a working method of a module series frequency converter. Fig.18 FIG. 6 is a flowchart showing a method 6000 for operating a module series inverter according to some embodiments of the present invention. Fig.18 As shown, the working method 6000 includes steps S610 to S650.

[0105] In step S610, a control signal is sent through a main controller of the modular series inverter.

[0106] In step S620, a control signal is sent to a first photoelectric conversion circuit via a first optical fiber.

[0107] In step S630, the control signal is photoelectrically converted by the first photoelectric conversion circuit.

[0108] In step S640, the photoelectrically converted control signals are respectively sent to the first power units of the three power unit groups.

[0109] In step S650, the control signal is sent to the second power units of the three power unit groups through the isolation devices in the three isolation device groups respectively.

[0110] In some embodiments, each isolation device group includes a plurality of isolation devices, and the plurality of 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 via the first isolation device. The working method 6000 also includes: sending the photoelectrically converted control signal to the first isolation devices of the three isolation device groups respectively.

[0111] In some embodiments, the first power unit includes a first controller, the second power unit includes a second controller, and the working method 6000 also includes: receiving a converted control signal from the 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; receiving the converted control signal from the second isolation device through the second controller.

[0112] In some embodiments, the first power unit includes a first controller, the second power unit includes a second controller, and the working method 6000 also includes: receiving a converted control signal from the 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; receiving the converted control signal from the second isolation device through the second controller.

[0113] In some embodiments, each isolation device group further includes a third isolation device and a fourth isolation device, the third isolation device connects the second power unit with the first power unit, and the fourth isolation device connects the first power unit with the first photoelectric conversion circuit.

[0114] In some embodiments, the working method 6000 also 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.

[0115] In some embodiments, the working method 6000 also 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.

[0116] In some embodiments, the working method 6000 further includes: determining, by the first controller, state information of the first power unit, and sending the state information of the first power unit to the fourth isolation device.

[0117] In some embodiments, the working method 6000 also 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 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, and sending it to the main controller via the first optical fiber after photoelectric conversion.

[0118] In some embodiments, the modular series inverter further includes: a second photoelectric conversion circuit, the second photoelectric conversion circuit connecting the second power unit and the main controller.

[0119] In some embodiments, the working method 6000 also 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.

[0120] In some embodiments, the working method 6000 also 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.

[0121] In some embodiments, the working method 6000 further includes: determining state information of the second power unit by a second controller, and sending the state information of the second power unit to the second photoelectric conversion circuit.

[0122] In some embodiments, each isolation device group also includes: a fifth isolation device, the fifth isolation device connects 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 6000 also 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, and sending it to the main controller via the second optical fiber after photoelectric conversion.

[0123] In some embodiments, each power unit has an independent communication address, and the working method 6000 further includes: the main controller communicates with the power unit based on the communication address and a private protocol; and the power units communicate with each other based on the private protocol.

[0124] The working method 6000 of the modular series inverter of the utility model can be implemented by the above-mentioned modular series inverter 1000 / 2000 / 3000 / 4000, which can greatly reduce the use of optical fiber and optical fiber transceiver, reduce costs, and improve communication quality and communication reliability.

[0125] The utility model also provides a computer-readable storage medium, including computer executable instructions stored thereon, and the executable instructions implement the working method 6000 as described above when executed by a processor.

[0126] In some embodiments, a computer readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination 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, more specific examples (a non-exhaustive list) include: an electrical connection with one or more conductors, a portable computer hard disk, a hard disk, a random access memory (RAM), a non-volatile random access memory (NVRAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0127] It should be noted that this specification provides method operation steps such as embodiments or schematic diagrams, but more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual system or device product is executed, it can be executed in the order of the method shown in the embodiment or flowchart or in parallel.

[0128] It should be noted that any embodiments or combinations of the modular series inverter, the working method of the modular series inverter, the inverter system and the computer-readable storage medium disclosed in the present invention can be applied to each other, and these are all within the protection scope of the present utility model.

[0129] 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), and may also include other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), complex programmable logic devices (CPLD) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components and other similar devices.

[0130] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A modular series inverter, characterized in that: include: Main controller; The photoelectric conversion circuit includes a first photoelectric conversion circuit, wherein the first photoelectric conversion circuit is connected to the main controller via a first optical fiber communication; three power unit groups, each power unit group includes a plurality of power units, the plurality of 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 three isolation device groups, each isolation device group including one or more isolation devices; The power unit groups correspond to the isolation device groups one by one, and in each power unit group, the first power unit is communicatively connected with the second power unit through the isolation device.

2. The modular series inverter according to claim 1, characterized in that: Each isolation device group includes a plurality of isolation devices, wherein the plurality of isolation devices include at least a first isolation device and a second isolation device, and the first power unit is connected to the first photoelectric conversion circuit via the first isolation device.

3. The modular series inverter according to claim 2, characterized in that: The main controller is configured to send a control signal, which is sent 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.

4. The modular series inverter according to claim 3, characterized in that: The first power unit includes a first controller, the second power unit includes a second controller, and 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.

5. The modular series inverter according to claim 3, characterized in that: 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.

6. The modular series inverter according to claim 4 or 5, characterized in that: 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.

7. The modular series inverter according to claim 6, characterized in that: 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 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 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 series inverter according to claim 6, characterized in that: 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 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 series inverter according to claim 6, characterized in that: 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 series inverter according to claim 6, characterized in that: 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 status information of the first power unit and / or the second power unit from the fourth isolation device, and send it to the main controller via the first optical fiber after performing photoelectric conversion.

11. The modular series inverter according to claim 4 or 5, characterized in that: The photoelectric conversion circuit further includes: a second photoelectric conversion circuit, and the second photoelectric conversion circuit connects the second power unit and the main controller.

12. The modular series inverter according to claim 11, characterized in that: 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 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 status information of the first power unit and send the status information of the first power unit to the second photoelectric conversion circuit.

13. The modular series inverter according to claim 11, characterized in that: 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 status information of the first power unit and send the status information of the first power unit to the second photoelectric conversion circuit.

14. The modular series inverter according to claim 11, characterized in that: The second controller is configured to determine state information of the second power unit and send the state information of the second power unit to the second photoelectric conversion circuit.

15. The modular series inverter according to claim 11, characterized in that: Each isolation device group also includes: a fifth isolation device, which connects 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 status information of the first power unit and / or the second power unit is sent to the second photoelectric conversion circuit via the fifth isolation device; the second photoelectric conversion circuit is configured to receive the status information of the first power unit and / or the second power unit, and send it to the main controller via the second optical fiber after performing photoelectric conversion.

16. The modular series frequency converter according to any one of claims 1 to 5, characterized in that: 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 modular series inverter according to claim 11, characterized in that: The second photoelectric conversion circuit is arranged outside or inside the second power unit.

18. The modular series frequency converter according to any one of claims 1 to 5, characterized in that: The isolation device is arranged outside or inside the power unit.

19. The modular series frequency converter according to any one of claims 1 to 5, characterized in that: The isolation device is arranged outside or inside the photoelectric conversion circuit.

20. The modular series frequency converter according to any one of claims 1 to 5, characterized in that: The isolation device includes at least one of an optical isolator, a magnetic coupling isolation device and a capacitive isolator.

21. The modular series frequency converter according to any one of claims 1 to 5, characterized in that: 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.

22. A frequency converter system, characterized in that: It comprises a modular series frequency converter as claimed in any one of claims 1 to 21.

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