A multi-level unit communication synchronous power electronic transformer

Abstract

The present invention relates to a multi-level unit communication synchronous power electronic transformer, each unit has a high-frequency transformer, and a primary circuit and a secondary circuit of the high-frequency transformer, and: a main controller, N primary controllers and N secondary controllers; each unit corresponds to a primary controller and a secondary controller, the primary controller is used to interact and control the primary circuit, and the secondary controller is used to interact and control the secondary circuit; a serial communication channel is provided between the main controller and the primary controller, and a serial communication channel is also provided between the primary controller and the secondary controller; the serial communication channel is an optical fiber channel. The present invention can reduce the optical fiber and optical fiber interface data, as well as the resource consumption of the main controller, and reduce the cost. And combined with software, the synchronization of data transmission and reception between each level of units and the synchronization of primary / secondary PWM control are realized.

Description

Technical Field

[0001] The invention relates to the field of power electronic transformers, in particular to a power electronic transformer capable of realizing multi-level unit communication synchronization. Background Art

[0002] With the deployment and construction of distributed power sources across the country, higher requirements are placed on the power grid in terms of port diversity for accessing distributed energy and controllability of energy flow.

[0003] Power electronic transformers are a type of transformer that uses a fully controlled converter and a high-frequency transformer. They can achieve voltage conversion, electrical isolation, energy flow control, and provide multiple ports to facilitate the access of distributed energy and energy storage devices. At present, power electronic transformers are often used in medium and high voltage and high power applications, so multi-stage DC / DC modules are generally required to be cascaded to meet the needs of high voltage and high power. The main configurations of DC / DC modules include: DAB converter, Boost+DAB converter, LLC resonant converter, etc.

[0004] like Figure 1 As shown, a power electronic transformer built based on Boost+DAB unit. In order to be applied to medium and high voltage occasions (above 10kV), and the voltage resistance of the switch device is limited, its input end needs to be cascaded with multiple units, and the output end relies on multiple units in parallel to ensure high output power. That is, the power electronic transformer is composed of multiple DC / DC units (DC / DC unit 1, DC / DC unit 2, DC / DC unit 3, DC / DC unit 4...), each DC / DC unit includes a Boost circuit, a primary converter, a high-frequency transformer and a secondary converter, and both the primary converter and the secondary converter adopt an H-bridge structure. The input ends of each Boost circuit are cascaded, and the output ends of the secondary converters are paralleled.

[0005] From the perspective of overall control requirements, the synchronization of sending and receiving information and the drive synchronization generation control must be ensured between multi-level units. From the perspective of unit composition, in the Boost+DAB unit, the primary side of the high-frequency transformer bears a larger voltage and the secondary side bears a smaller voltage. The sampling volume needs to sample the primary side Boost bus voltage and boost input current, and the secondary side needs to sample the DAB output voltage and current. In order to ensure the isolation sampling of the primary and secondary sides, it is usually necessary to configure the primary and secondary side controllers to complete the sampling and drive control respectively to ensure the insulation and signal isolation of the transformer.

[0006] Therefore, in order to meet the requirements of control and balance, it is necessary to ensure the synchronization of communication between multi-level units and within the units. The existing technology generally adopts a master-slave structure, including a master controller and a slave controller, and uses optical fiber to achieve communication and isolation. However, the defects of the existing technology include too many optical fiber interfaces, occupying more resources of the master controller, and high cost. Summary of the invention

[0007] The purpose of the present application is to provide a multi-level unit communication synchronous power electronic transformer to solve the problem of multiple optical fiber interfaces and high resource occupation in the prior art.

[0008] To achieve the above object, the present invention proposes a multi-level unit communication synchronous power electronic transformer, each unit having a high-frequency transformer, and a primary circuit and a secondary circuit of the high-frequency transformer, and:

[0009] One main controller, N primary side controllers and N secondary side controllers;

[0010] Each unit corresponds to a primary side controller and a secondary side controller, the primary side controller is used to interact and control the primary side circuit, and the secondary side controller is used to interact and control the secondary side circuit;

[0011] A serial communication channel is provided between the main controller and the primary side controller, and a serial communication channel is also provided between the primary side controller and the secondary side controller; the serial communication channel is an optical fiber channel.

[0012] Furthermore, the serial communication data is encoded by Manchester encoding.

[0013] Further, after the primary side controller starts to receive the control data from the main controller, it sets its synchronization signal and directly forwards the control data to the secondary side controller; after the primary side controller completes receiving, it pulls down its synchronization signal;

[0014] When the secondary side controller starts to receive the control data forwarded by the primary side controller, it sets its synchronization signal; after the secondary side controller completes receiving the control data, it pulls down its synchronization signal.

[0015] Furthermore, the primary-side controller performs PWM control based on the falling edge of its synchronization signal; and the secondary-side controller performs PWM control based on the falling edge of its synchronization signal.

[0016] Furthermore, for the primary side / secondary side control, when the data starts to be received, the receiving flag Flag_rx is set to "1", and after the reception is completed, the receiving flag Flag_rx is set to "0", and the receiving register reg1 is set to store the read flag, with reg1 = "10" as the sign of the completion of reception; when the data starts to be sent, the sending flag Flag_tx is set to "1", and after the reception is completed, the reading flag Flag_tx is set to "0", and the receiving register reg2 is set to store the sending flag, with reg2 = "10" as the sign of the completion of sending.

[0017] The present invention also provides a multi-level unit communication synchronous power electronic transformer, each unit having a high-frequency transformer, and a primary circuit and a secondary circuit of the high-frequency transformer, and:

[0018] A main controller, N primary side controllers and N secondary side controllers;

[0019] Each unit corresponds to a primary side controller and a secondary side controller, the primary side controller is used to interact and control the primary side circuit, and the secondary side controller is used to interact and control the secondary side circuit;

[0020] A serial communication channel is provided between the main controller and the secondary controller, and a serial communication channel is also provided between the primary controller and the secondary controller; the serial communication channel is an optical fiber channel.

[0021] Furthermore, the serial communication data is encoded by Manchester encoding.

[0022] Further, when the secondary controller starts to receive the control data from the primary controller, it sets its synchronization signal and directly forwards the control data to the primary controller; after the secondary controller completes receiving the control data, it pulls down its synchronization signal;

[0023] After the primary side controller starts to receive the control data forwarded by the secondary side controller, it sets its synchronization signal; after the primary side controller completes receiving, it pulls down its synchronization signal.

[0024] Furthermore, the primary-side controller performs PWM control based on the falling edge of its synchronization signal; and the secondary-side controller performs PWM control based on the falling edge of its synchronization signal.

[0025] Furthermore, for the primary side / secondary side control, when the data starts to be received, the receiving flag Flag_rx is set to "1", and after the reception is completed, the receiving flag Flag_rx is set to "0", and the receiving register reg1 is set to store the read flag, with reg1 = "10" as the sign of the completion of reception; when the data starts to be sent, the sending flag Flag_tx is set to "1", and after the reception is completed, the reading flag Flag_tx is set to "0", and the receiving register reg2 is set to store the sending flag, with reg2 = "10" as the sign of the completion of sending.

[0026] The beneficial effects of the present invention are as follows: firstly, through the communication layout of the main controller and the primary / secondary controllers, the optical fiber and the interface, as well as the resource consumption of the main controller are reduced, thereby reducing the cost.

[0027] Furthermore, the Manchester encoding method can include clock information and further reduce the number of optical fiber interfaces.

[0028] Furthermore, since the primary / secondary side controller directly forwards the data from the main controller, the data transmission and reception of each unit can be synchronized through the respective synchronization signals, thereby conveniently realizing the synchronization of data transmission and reception between units at all levels.

[0029] Moreover, the synchronization signal can also be used to synchronize the PWM signals of the primary and secondary controllers. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a multi-level cell topology;

[0031] Figure 2 It is a communication structure diagram of the present invention;

[0032] Figure 3 It is a schematic diagram of Manchester coding;

[0033] Figure 4 It is a schematic diagram of data transmission and reception synchronization. DETAILED DESCRIPTION

[0034] This embodiment is introduced by taking a power electronic transformer with a Boost+DAB structure as an example. It should be noted that the technical solution of the present invention can be applied to other types of power electronic converters.

[0035] like Figure 2 The circuit diagram of this embodiment is shown in FIG. Figure 1 The same, no further elaboration. Figure 2 The relevant control components are shown in Figure 1, including the main controller, primary controller and secondary controller. Each DC / DC unit is equipped with a primary controller and a secondary controller; the primary controller is used to control the Boost circuit and the primary converter, and collect input voltage and current; the secondary controller is used to control the secondary controller, and uses output voltage and current; the primary controller is connected to the secondary controller by optical fiber communication. The main controller is connected to the primary controller of each unit by optical fiber communication. Figure 2 It can be seen that TX11 and RX11 of the main controller correspond to DC / DC unit 1, and TXN1 and RXN1 correspond to DC / DC unit N.

[0036] The main controller communicates with the primary controller only through a pair of optical fibers, and the secondary controller is connected to the primary controller only through a pair of optical fibers (2 channels). Therefore, each unit has less demand for the data resources and communication interface of the main controller, which greatly increases the number of controllable unit groups of the conventional main controller platform. In addition, the number of optical fibers used for communication synchronization control is small, and the communication cost is low. The primary controller generates a total of 6 switch drives for the boost half bridge and the DAB primary H bridge, and is responsible for sampling the input voltage and current. The secondary controller generates 4 switch drives for the DAB secondary H bridge and is responsible for sampling the output voltage and current. Therefore, in the actual circuit design, the primary controller and the secondary controller can use the same circuit schematic and PCB board design to simplify the control platform development process and time.

[0037] like Figure 2 Taking DC / DC unit 1 as an example, the data sent synchronously by the main controller (through the TX11 optical fiber port) is transmitted to the optical fiber port RX12 of the primary controller. At the same time, the code is written through the primary controller to make the output and input port TX13 of the primary controller = RX12, that is, the primary controller is used as an intermediary to directly forward the secondary control data. Since the optical fiber of the primary and secondary controllers is shorter and the transmission rate is high, the delay caused by forwarding can be completely ignored. Therefore, the optical fiber port RX12 of the primary controller and the optical fiber port RX14 of the secondary controller receive data synchronously. In addition, the secondary controller sends the collected information to the optical fiber port RX13 of the primary through the optical fiber port TX14, and the primary controller sends the collected information and the information received from the secondary controller to the optical fiber port RX11 of the main controller through the optical fiber port TX12.

[0038] In this embodiment, the main controller is a single chip microcomputer, and the primary side controller and the secondary side controller are implemented by FPGA.

[0039] like Figure 3 As shown, since Manchester encoding can contain clock information, in this embodiment, in order to reduce the fiber interface, the serial fiber channel is encoded by Manchester encoding. Based on the clock CLK of the main controller, the data value to be sent is confirmed at the center of each clock cycle (i.e., the falling edge of CLK). If the data is "1", the Manchester encoding generates a falling edge (i.e., a jump from 1 to 0), and if the data is "0", the Manchester encoding generates a rising edge (i.e., a jump from 0 to 1), and finally the data code converted into Manchester form is obtained. It can be seen that the data code contains both data information and the internal clock CLK of the sending subject, which can transmit two types of information, data and main controller clock. The clock information can be used as a synchronization correction signal for the receiving object.

[0040] In the absence of a dedicated clock data channel, it is necessary to consider how to synchronize communication and control. Figure 4As shown, after the optical fiber port of the primary controller RX12 receives data, the receiving flag Flag_rx is set to "1". After the data is read, Flag_rx is set to "0". The register reg1 is set to store a binary two-digit number, and reg1 = reg1 (1) & Flag_rx (the corresponding data under the two clocks before and after Flag_rx is stored). Only when reg1 = "10" (i.e., Flag_rx is delayed by one CLK cycle after the falling edge appears), the synchronization correction signal Sync has a falling edge, and the falling edge enables the primary controller to send data. When the optical fiber port TX13 starts to send data, Flag_tx is set to "1" as the sending flag. After the data is sent, Flag_tx is set to "0". The register reg2 is set to store a binary two-digit number, and reg2 = reg2 (1) & Flag_tx (the corresponding data under the two clocks before and after Flag_tx is stored). Only when reg2 = "10" (i.e., Flag_tx is delayed by one CLK cycle after the falling edge appears), the synchronization correction signal Sync has a rising edge, and the data transmission and reception synchronization process ends. Similarly, RX13 and TX12 can also be controlled in this way.

[0041] Similarly, the secondary controller RX14 and TX14 optical fiber ports send and receive data, and also set corresponding flags, registers and synchronization signals Sync, using the same control method as above. In other words, the primary controller and the secondary controller have their own synchronization signals, registers, flags, etc. For the convenience of representation, this article will no longer distinguish the signal labels.

[0042] Among them, the synchronization signal Sync plays the role of synchronous data transmission and reception. In addition, the falling edge of Sync is used as the reference signal of the primary and secondary controllers, that is, in the PWM generation link of the primary and secondary controllers, the falling edge of Sync is used as the correction enable signal of the carrier count value. The falling edge of Sync indicates that the data reception is completed, and the primary and secondary controllers obtain their respective phase shift, proportion and other information. The phase shift value determines the initial value of the carrier count, that is, with the falling edge of Sync as a sign, the received phase shift value is assigned to the initial value of the carrier count, ensuring that the carrier used in the PWM generation of the primary and secondary controllers can count synchronously, ensuring the synchronization of the drive control generated by PWM.

[0043] In this embodiment, the realization of communication synchronization control not only depends on the hardware connection structure of the main controller, the primary controller and the secondary controller, but also depends on the software design - the synchronization signal Sync is set in the primary controller and the secondary controller, and the synchronization of data transmission and reception, as well as the synchronization of the PWM signal of the primary and secondary controllers are conveniently realized through the synchronization signal Sync. It should be noted that when the hardware connection method of this embodiment is adopted, the existing software design can also be adopted, for example, the synchronization tag is transmitted between the main controller, the primary controller and the secondary controller through a serial channel, so as to realize communication synchronization; but the existing software design method is more complicated to implement than the method of this embodiment.

[0044] In this embodiment, when receiving data, Sync is high, and a falling edge is generated after the reception is completed. Obviously, it can also be set that when receiving data, Sync is low, and a rising edge is generated after the reception is completed; these technical means are equivalent technical means in the field.

[0045] In this embodiment, the main controller is connected to the primary side controller, and the primary side controller is connected to the secondary side controller; from the perspective of communication control, the primary side controller and the secondary side controller are actually equivalent, so as another implementation method, the main controller can be connected to the secondary side controller, and the secondary side controller can be connected to the primary side controller.

Claims

1. A multi-level unit communication synchronous power electronic transformer, characterized in that: Each unit has a high-frequency transformer, a primary circuit and a secondary circuit of the high-frequency transformer, and: One main controller, N primary side controllers and N secondary side controllers; Each unit corresponds to a primary side controller and a secondary side controller, the primary side controller is used to interact and control the primary side circuit, and the secondary side controller is used to interact and control the secondary side circuit; Each group of input and output ports of the main controller corresponds to each unit one by one and is provided with a serial communication channel between the primary controller of the corresponding unit, and a serial communication channel is also provided between the primary controller and the secondary controller; the serial communication channel is an optical fiber channel; The data sent by the output port of the primary controller to the input port of the secondary controller is consistent with the data synchronously sent by the main controller received by the input port of the primary controller, so that the input port of the primary controller receives data synchronously with the input port of the secondary controller.

2. The multi-level unit communication synchronous power electronic transformer according to claim 1, characterized in that: The serial communication data is encoded by Manchester encoding.

3. The multi-level unit communication synchronous power electronic transformer according to claim 2, characterized in that: After the primary side controller starts to receive the control data from the main controller, it sets its synchronization signal and directly forwards the control data to the secondary side controller; after the primary side controller completes receiving the control data, it pulls down its synchronization signal; When the secondary side controller starts to receive the control data forwarded by the primary side controller, it sets its synchronization signal; after the secondary side controller completes receiving the control data, it pulls down its synchronization signal.

4. The multi-level unit communication synchronous power electronic transformer according to claim 3, characterized in that: The primary side controller performs PWM control based on the falling edge of its synchronization signal; the secondary side controller performs PWM control based on the falling edge of its synchronization signal.

5. The multi-level unit communication synchronous power electronic transformer according to claim 2, characterized in that: For primary / secondary side control, when data starts to be received, the receiving flag Flag_rx is set to "1". After receiving, the receiving flag Flag_rx is set to "0". The receiving register reg1 is set to store the read flag, and reg1 = "10" is used as a sign of receiving completion. When data starts to be sent, the sending flag Flag_tx is set to "1". After receiving, the reading flag Flag_tx is set to "0". The receiving register reg2 is set to store the sending flag, and reg2 = "10" is used as a sign of sending completion.

6. A multi-level unit communication synchronous power electronic transformer, characterized in that: Each unit has a high-frequency transformer, a primary circuit and a secondary circuit of the high-frequency transformer, and: A main controller, N primary side controllers and N secondary side controllers; Each unit corresponds to a primary side controller and a secondary side controller, the primary side controller is used to interact and control the primary side circuit, and the secondary side controller is used to interact and control the secondary side circuit; Each group of input and output ports of the main controller corresponds to each unit one by one and is provided with a serial communication channel between the secondary controller of the corresponding unit, and a serial communication channel is also provided between the primary controller and the secondary controller; the serial communication channel is an optical fiber channel; The data sent by the output port of the primary controller to the input port of the secondary controller is consistent with the data synchronously sent by the main controller received by the input port of the primary controller, so that the input port of the primary controller receives data synchronously with the input port of the secondary controller.

7. The multi-level unit communication synchronous power electronic transformer according to claim 6, characterized in that: The serial communication data is encoded by Manchester encoding.

8. The multi-level unit communication synchronous power electronic transformer according to claim 7, characterized in that: When the secondary controller starts to receive control data from the primary controller, it sets its synchronization signal and directly forwards the control data to the primary controller; after the secondary controller completes receiving the control data, it pulls down its synchronization signal; After the primary side controller starts to receive the control data forwarded by the secondary side controller, it sets its synchronization signal; after the primary side controller completes receiving, it pulls down its synchronization signal.

9. The multi-level unit communication synchronous power electronic transformer according to claim 8, characterized in that: The primary side controller performs PWM control based on the falling edge of its synchronization signal; the secondary side controller performs PWM control based on the falling edge of its synchronization signal.

10. The multi-level unit communication synchronous power electronic transformer according to claim 7, characterized in that: For primary / secondary side control, when data starts to be received, the receiving flag Flag_rx is set to "1". After receiving, the receiving flag Flag_rx is set to "0". The receiving register reg1 is set to store the read flag, and reg1 = "10" is used as a sign of receiving completion. When data starts to be sent, the sending flag Flag_tx is set to "1". After receiving, the reading flag Flag_tx is set to "0". The receiving register reg2 is set to store the sending flag, and reg2 = "10" is used as a sign of sending completion.

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