Modular power conversion system and communication method thereof

Abstract

This application discloses a modular power conversion system and its communication method, wherein a central controller and multiple power units communicate via a ring fiber optic network. The central controller is configured to generate and transmit signal frames with one or more fault indication bits, and each power unit's local controller is configured to continuously output fault indication bits indicating a fault state in response to the absence of a fault indication bit indicating a normal state within a preset time period or in response to the detection of an internal fault. In this manner, fault information can be rapidly transmitted in the event of a serious fault, and corresponding protective measures can be implemented within microseconds, thereby providing rapid protection for the modular power conversion system.

Description

Technical Field

[0001] This application relates to the field of power electronic control, and in particular to communication control and fast protection methods for modular power conversion systems. Background Technology

[0002] Modular power conversion systems, through the cooperation of a central controller and local controllers in each power unit, can flexibly support multiple voltage and power levels and offer high reliability and redundancy design. They are widely used in high-voltage / high-power applications. Taking a medium-voltage solid-state transformer as an example, multiple medium-voltage power units are connected in series to modulate the medium-voltage voltage, while multiple low-voltage power units are connected in parallel to provide very high power output.

[0003] In a modular power conversion system, all power units need to communicate with a central controller. When a critical fault occurs in one of the power units, rapid protection is required to shut down the entire system. Improving the speed of fault broadcasting to achieve rapid protection in a modular power conversion system is a challenging task. Summary of the Invention

[0004] The purpose of this application is to provide a fast protection scheme for modular power conversion systems that can quickly transmit fault information and implement corresponding protection measures within microseconds in the event of a serious fault.

[0005] According to a first aspect of the embodiments of this application, a system is provided comprising a central controller and a plurality of power units, wherein the central controller and local controllers of each power unit communicate via a ring fiber optic network. The central controller is configured to generate and transmit signal frames with one or more fault indication bits, and to continuously output fault indication bits indicating a fault state in response to the absence of a fault indication bit indicating a normal state within a preset time period or in response to the detection of an internal fault. The local controllers of the power units are configured to continuously output fault indication bits indicating a fault state in response to the absence of a fault indication bit indicating a normal state within a preset time period or in response to the detection of an internal fault.

[0006] In some embodiments, the central controller may also be configured to insert fault indication bits into the data payload of a signal frame at preset intervals. In some embodiments, a fault indication bit may be spaced between every two valid data bits in the signal frame. In some embodiments, the preset time period may be set to two baud rate cycles. In some embodiments, the preset time period may be determined based on the position of the fault indication bit in the signal frame.

[0007] In some embodiments, the central controller may also be configured to generate and send a reset signal in response to an external instruction, and the local controller of the power unit may also be configured to stop outputting a fault indication bit indicating a fault state in response to receiving a reset signal.

[0008] According to a second aspect of the embodiments of this application, a communication method for a modular power conversion system is provided. The modular power conversion system includes a central controller and multiple power units. The central controller and the local controllers of each power unit communicate through a ring optical fiber network. The method includes: generating and sending a signal frame with one or more fault indication bits by the central controller; and continuously outputting fault indication bits indicating a fault state by the central controller and the local controllers of each power unit in response to the absence of a fault indication bit indicating a normal state within a preset time period or in response to the detection of an internal fault.

[0009] In some embodiments, the one or more fault indication bits may be inserted into the data payload of a signal frame at preset intervals. In the signal frame, a fault indication bit may be spaced between every two valid data bits. The preset time period may be set to two baud rate cycles.

[0010] In the embodiments of this application, the central controller communicates with the local controller of each power unit through a fiber-optic ring network and can quickly transmit fault information in the event of a serious fault, implementing corresponding protective measures within microseconds, thereby providing rapid protection for the modular power conversion system. Simultaneously, this scheme integrates communication and rapid protection functions into a single communication ring, saving a significant amount of fiber optic cable.

[0011] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0012] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0013] Figure 1 A schematic diagram of the communication structure of a modular power conversion system according to an embodiment of this application is shown.

[0014] Figure 2 A schematic diagram of the structure of a data frame used for communication in a modular power conversion system according to an embodiment of this application is shown.

[0015] Figure 3 This diagram illustrates the valid data bits and fault indication bits in a data frame according to an embodiment of this application.

[0016] Figure 4 A flowchart illustrating a communication method in a modular power conversion system according to an embodiment of this application is shown. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this application. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0018] Furthermore, unless otherwise specified, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application may be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc. may be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0019] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0020] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0021] Modular power conversion systems typically consist of a central controller and multiple power units. The central controller communicates with each power unit via a network. Each power unit is equipped with a local controller, which works in conjunction with the central controller. The local controllers are responsible for monitoring and controlling the operating status of their respective power units (such as input / output voltage and current) and feeding this status information back to the central controller. The central controller can then perform global optimization and coordination based on this feedback. For example, the central controller can send control commands to each power unit based on the overall system requirements. Each power unit's local controller adjusts its operating status according to the received control commands. Furthermore, when an anomaly is detected, the local controller can send fault information to the central controller via the network, allowing the central controller to take measures such as shutting down the faulty unit or adjusting the operating status of other units.

[0022] In existing modular power conversion systems, a star network topology is typically used between the central controller and each power unit. Each power unit is connected to the central controller via a dedicated optical fiber. While this structure ensures timely and reliable communication between the central controller and each power unit, the large amount of optical fiber not only occupies system deployment space and increases deployment complexity, but also incurs high hardware costs.

[0023] Some modular power conversion systems also employ a ring topology, integrating the central controller and each power unit into a communication ring. This saves a significant amount of fiber optic cable and reduces deployment complexity and hardware costs. In a ring-based network, the central controller sends information to the power units directly connected to it. Each power unit's controller receives information from the previous node in the ring network and transmits it to the next node, until it returns to the central controller. However, the inventors discovered in practice that each node in the ring network requires a certain amount of time to receive or transmit a data frame. This accumulated time across nodes leads to a delay in information transmission. Especially when a fault is detected in a power unit, it often takes hundreds of microseconds to notify all nodes in the ring network of the fault information, making it difficult to quickly protect the entire modular power conversion system.

[0024] In response, this application provides a novel solution for modular power conversion systems that use a ring topology for communication. This solution can quickly notify each node in the ring network of fault information, thereby enabling appropriate protective measures (such as shutting down the entire system) to be taken within microseconds, thus achieving rapid protection of the modular power conversion system.

[0025] Figure 1A schematic diagram of the communication structure of a modular power conversion system according to an embodiment of this application is shown. The modular power conversion system includes a central controller and multiple power units. The central controller communicates with each power unit via a fiber-optic ring bus network. Each power unit is equipped with a local controller for monitoring and controlling the operating status of its respective power unit. These local controllers work in conjunction with the central controller.

[0026] In this ring bus network, the basic unit of transmission is a data frame or control frame (hereinafter referred to as a signal frame for convenience). A signal frame typically includes a frame header, a data payload, and a frame trailer. The frame header may contain information such as the source address (the address of the node sending the signal frame), the destination address (the address of the node receiving the signal frame), and the frame type. The data payload is the actual data content to be transmitted, and the frame trailer may contain some checksum information for error detection, such as a Cyclic Redundancy Check (CRC) code. The sending node encapsulates the data to be transmitted, adding frame header and trailer information. The encapsulated signal frame is sent to the ring network through the fiber optic interface. In fiber optic communication, the binary data (0s and 1s) in the signal frame is converted into corresponding changes in optical signal intensity. The receiving node's fiber optic interface receives the optical signal and converts it into a digital signal.

[0027] In this embodiment, the central controller inserts one or more fault indication bits into each signal frame to be transmitted according to a preset rule, so that each node in the ring network can receive the corresponding fault indication bit at a preset time interval. Thus, the local controller of each power unit can promptly understand whether an external fault has occurred in the network based on the received fault indication bits, and can take corresponding protective measures. Simultaneously, the local controller of each power unit can also quickly notify other nodes in the ring of internal faults occurring locally within that power unit by setting or adjusting the fault indication bits in the signal frame, enabling other nodes to take timely protective measures.

[0028] like Figure 2 As shown, the signal frame format used in some embodiments of this application includes a header, a data payload, and a cyclic redundancy check (CRC) as the frame tail. Figure 2 In network communication, IDLE represents the idle state between frames. During the idle state, specific signals are typically transmitted to maintain the stability, synchronization, and integrity of the communication link. These signals may include, for example, an idle code to indicate that the network is idle, specific voltage levels corresponding to the idle state, or meaningless signals used to fill in the idle time. Figure 2Each frame header is represented by a high-level signal of a predetermined duration. When each node receives consecutive "1"s within the predetermined time period, it recognizes this as the frame header and begins receiving subsequent data payloads. In addition to the data to be transmitted, one or more fault indication bits (also called fault indication bits) are inserted into the data payload. In some embodiments, corresponding fault indication bits can be inserted at one or more predetermined positions in the data payload, such as at the beginning, middle, or end of the data payload. In other embodiments, fault indication bits can be inserted into the data payload at preset intervals, such as one fault indication bit every other data bit, or one fault indication bit every two data bits, and so on. However, the fewer data bits at the interval, the less time is required for fault detection and fault notification, making it easier to implement faster protection. Preferably, one fault indication bit is inserted every other data bit, so that each node only needs to receive two consecutive bits to detect a fault and respond to it or notify it of a fault.

[0029] by Figure 3 Taking the data payload shown as an example, in Figure 3 The shaded area in the upper half corresponds to the valid data bits, with a fault indicator bit between every two valid data bits. When no fault occurs, each fault indicator bit is represented by a "1". When a fault is detected, the fault indicator bit is set to "0". Therefore, when no fault occurs, if... Figure 3 If the actual data content to be transmitted in the data payload is 011001, then the waveform of the signal frame actually transmitted over the communication network is as follows: Figure 3 The lower half indicates the waveform 01111101011. It should be understood that in other embodiments, for the fault indication bit, "0" may represent a normal state, and "1" may represent a fault. For ease of description, this document will use the example of each fault indication bit being "1" to indicate no fault.

[0030] Still with Figure 3 The signal frame shown (01111101011) with fault indication bit is used as an example, combined with Figure 4 This section describes the fault detection process of the local controller for each power unit. The fault detection process mainly includes external fault detection, internal fault detection, fault latching, and output. External faults refer to faults occurring outside the power unit, such as faults in other power units within the network. Internal faults refer to faults occurring within the power unit itself. When an external fault is detected, each power unit needs to implement appropriate protective measures and transmit the fault information to its subsequent nodes. When an internal fault is detected, each power unit needs to promptly transmit the fault information to other nodes in the network.

[0031] like Figure 4 As shown, each power unit has a receive port RX and an output port TX. Under normal conditions, each power unit should receive one or two "1" bits every two baud rate cycles at its receive port RX, because... Figure 3 As shown in the signal frame transmitted over the fiber optic network, a fault indication bit (set to "1" under normal conditions) is spaced between every two valid data bits. The baud rate period refers to the duration of each bit, i.e., the time required to receive or transmit one bit, and is the reciprocal of the baud rate. In other words, if the local controller of each power unit can receive a "1" bit at RX every two baud rate periods, it means that at least all power units upstream of that power unit in the network are currently operating normally, indicating that no external fault has been detected for that power unit.

[0032] If the local controller does not detect a "1" bit at RX for two consecutive baud rate cycles, it indicates at least an external fault has been detected. In response to the external fault detection, the local controller of this power unit immediately sets all outputs to "0" at the output interface TX to promptly notify the next node in the network of the fault information. This ensures that the receiving port of the next power unit can detect a "0" bit indicating a fault status for two consecutive baud rate cycles, thus enabling timely detection of external faults.

[0033] If the local controller of a power unit detects a fault in the power unit itself (an internal fault), it immediately sets all outputs at the output interface TX to "0", regardless of whether the bits received at the receive port RX from the previous node are 0 or 1. In this way, the fault information of the power unit can be promptly notified to other nodes in the network.

[0034] As can be seen, in the above embodiments, the power unit will immediately output a "0" bit indicating the fault status to the next power unit in response to the detection of either an internal fault or an external fault, and will not output any other valid data.

[0035] To enhance system stability and reliability, each power unit can maintain its fault state via a latch module upon detecting either an internal or external fault. This ensures that the power unit's output interface continuously outputs a "0" bit indicating the fault state until a reset signal is received. This reset signal is generated by the central controller. Upon receiving the reset signal, each power unit clears its latch module to restore the normal output function of its output interface. Under normal operating conditions, when no fault is detected, each power unit's controller can directly bypass the signal received from the receive interface RX to the output interface TX to expedite signal frame transmission.

[0036] The fault detection process of the central controller is almost identical to that of the local controllers of the power units, detecting both external and internal faults. The difference lies in the operation of the output interfaces. In normal mode, the central controller actively generates a signal frame with a fault indication bit and sends it through its output interface TX. However, the local controllers of each power unit do not actively generate such signal frames. Instead, they receive signals from the previous power unit through their receiving interface RX and, if no fault is detected, bypass the signal directly to their output interface TX to pass it on to the next power unit.

[0037] Figure 4 A flowchart illustrating a communication method for a modular power conversion system according to an embodiment of this application is shown. Figure 4 As shown, in step S1, the central controller generates and sends a signal frame with one or more fault indication bits, each fault indication bit being set to indicate a normal state. For example... Figure 3 As shown, a fault indication bit is spaced between every two valid data bits. This fault indication bit is set to "1" under normal conditions. In some other embodiments, fault indication bits can also be inserted into the data payload of the signal frame at other preset intervals. As mentioned above, the fewer data bits between intervals, the less time is required for subsequent fault detection and fault notification, which is more conducive to rapid protection. Preferably, a fault indication bit is inserted every other data bit, so that each node only needs to receive two consecutive bits to detect a fault and respond to it or notify it of a fault.

[0038] In step S2, the central controller and the local controllers of each power unit continuously output fault indicator bits indicating a fault state in response to the absence of a fault indicator bit indicating a normal state within a preset time period or in response to the detection of an internal fault. The fault indicator bits indicating a fault state have opposite Boolean values ​​to the fault indicator bits indicating a normal state, and are indicated by opposite level signals. Figure 3For example, if the fault indicator bit is set to "1" in the normal state, it will be set to "0" in the fault state, and vice versa.

[0039] The preset time period is associated with the specific position of the fault indication bit in the signal frame. If using... Figure 3 The signal frame shown represents a preset time period of two baud rate cycles. Under normal conditions, each power unit should receive at least one fault indication bit (indicating normal status) at its receiving port RX every two baud rate cycles; that is, it should receive one or two "1" bits. If not, it indicates an external fault has been detected. In response to the detection of either an external or internal fault, the local controller of that power unit immediately outputs a fault indication bit at its output interface TX, i.e., continuously outputting "0" bits, to promptly notify the next node in the network of the fault information. This ensures that the receiving port of the next power unit can detect the "0" bits indicating the fault status for two consecutive baud rate cycles, thus promptly detecting external faults.

[0040] In yet another embodiment, the method may further include: after the local controller of each power unit detects the first fault (whether an external or internal fault), continuously outputting a fault indication bit indicating the fault status, unless a reset signal is received; and the central controller generating a reset signal in response to an external command.

[0041] In modular power conversion systems, this communication method allows each node to rapidly transmit fault information in the event of a serious fault, without needing to transmit the entire signal frame. Corresponding protective measures are implemented within microseconds, thus providing rapid protection for the modular power conversion system. Furthermore, this method effectively integrates communication and rapid protection functions into the same communication loop, saving a significant amount of optical fiber.

[0042] References to "various embodiments," "some embodiments," "one embodiment," or "embodiment," etc., in this specification refer to a specific feature, structure, or property described in connection with the said embodiment, included in at least one embodiment. Therefore, the appearance of the phrases "in various embodiments," "in some embodiments," "in one embodiment," or "in an embodiment," etc., throughout this specification does not necessarily refer to the same embodiment. Furthermore, specific features, structures, or properties can be combined in any suitable manner in one or more embodiments. Therefore, a specific feature, structure, or property shown or described in connection with one embodiment can be combined, in whole or in part, with features, structures, or properties of one or more other embodiments without limitation, provided that the combination is not illogical or inoperable.

[0043] The terms "comprising," "having," and similar expressions used in this specification are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus. "A" or "an" does not exclude multiple instances. Furthermore, the elements in the accompanying drawings are for illustrative purposes only and are not drawn to scale.

[0044] Although the present invention has been described through the above embodiments, the present invention is not limited to the embodiments described herein, and includes various changes and variations without departing from the scope of the present invention.

Claims

1. A modular power conversion system, comprising a central controller and multiple power units, wherein the central controller and the local controllers of each power unit communicate via a ring fiber optic network, characterized in that: The central controller is configured to generate and send signal frames with one or more fault indication bits, and to continuously output fault indication bits indicating a fault state in response to the absence of a fault indication bit indicating a normal state within a preset time period or in response to the detection of an internal fault. The local controller of the power unit is configured to continuously output a fault indication bit indicating a fault state in response to the absence of a fault indication bit indicating a normal state within a preset time period or in response to the detection of an internal fault.

2. The system of claim 1, wherein the central controller is configured to insert a fault indication bit into the data payload of a signal frame at preset intervals.

3. The system according to claim 2, wherein in the signal frame, a fault indication bit is spaced between every two valid data bits.

4. The system according to claim 3, wherein the preset time period is two baud rate cycles.

5. The system according to claim 1, wherein the preset time period is determined based on the position of the fault indication bit in the signal frame.

6. The system of claim 1, wherein the central controller is further configured to generate and send a reset signal in response to an external instruction, and the local controller of the power unit is further configured to stop outputting a fault indication bit indicating a fault state in response to receiving the reset signal.

7. A communication method for a modular power conversion system, the modular power conversion system including a central controller and multiple power units, wherein the central controller and the local controllers of each power unit communicate via a ring fiber optic network, the method comprising: The central controller generates and sends a signal frame with one or more fault indication bits. The central controller and the local controller of each power unit continuously output a fault indication bit indicating the fault status in response to the absence of a fault indication bit indicating normal status within a preset time period or in response to the detection of an internal fault.

8. The method of claim 7, wherein the one or more fault indication bits are inserted into the data payload of the signal frame at preset intervals.

9. The system of claim 8, wherein in the signal frame, a fault indication bit is spaced between every two valid data bits.

10. The system according to claim 9, wherein the preset time period is two baud rate cycles.

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