A method and system for synchronous calibration of modular solid state transformer control devices

Abstract

The application provides a synchronization calibration method and system of a modular solid-state transformer control device, the modular solid-state transformer control device comprising one secondary side controller and n primary side controllers, n being an integer greater than or equal to 1, the synchronization calibration method comprising: the secondary side controller generating and broadcasting a communication signal; the primary side controllers receiving the communication signal, each primary side controller performing synchronization calibration according to the received communication signal, so that the control signal of the secondary side controller is synchronized with the control signal of the primary side controller. The synchronization calibration method provided by the embodiment of the application solves the technical problems of synchronization difficulty and insufficient synchronization precision in the prior art, realizes high-precision synchronization of the power transmission operation of the primary multi-stage power unit (primary side controller) and the secondary power unit (secondary side controller), and guarantees stable operation of the system.

Description

Technical Field

[0001] This invention relates to the field of power electronic control system technology, and in particular to a synchronous calibration method and system for a modular solid-state transformer control device. Background Technology

[0002] With the development of smart grids, energy storage systems, and other fields, traditional power frequency transformers, due to their large size and poor controllability, can no longer meet the needs of flexible power grids. Solid-state transformers (SSTs), as core equipment of high-frequency power electronics, have functions such as isolation, voltage regulation, and bidirectional current control. Among them, SSTs in the form of medium- and high-voltage direct-connected DC modules have broad application prospects.

[0003] Currently, medium- and high-voltage direct-connected DC modules (SST) generally adopt a multi-power unit series connection method to directly connect to the medium- and high-voltage power grid (including 10kV level). This method can share the high-voltage stress, reduce costs, and has the advantages of high power density and strong controllability. It has been widely studied and applied in the field of medium- and high-voltage power conversion.

[0004] However, the modular multi-power unit cascade and the inherent characteristics of SST place extremely high demands on control synchronization. Insufficient synchronization accuracy can lead to system malfunctions or even device damage, specifically manifested as follows: First, multiple units connected in series need to be precisely synchronized. If the switching transistors of each power unit do not operate in sync, it will lead to uneven voltage distribution and increased circulating current, which may damage the devices and cause system failure in severe cases. Secondly, the primary and secondary controllers need to work together. Deviations in PWM signal control can lead to abnormal power transmission, increased spikes and glitches, and damage to switching devices. Third, the system switching frequency is higher than 20kHz, requiring synchronous control accuracy higher than 20ns, which is difficult to meet using traditional methods.

[0005] Existing synchronization technologies all have shortcomings and cannot meet actual needs: independent clock sources have clock drift, and the cumulative deviation affects system operation; GPS synchronization is costly, has poor indoor signal, and is unreliable; the IEEE 1588 standard does not consider specific needs such as multi-unit broadcast synchronization and switching frequency coupling; simple communication synchronization does not compensate for fiber optic transmission delay and is not accurate enough.

[0006] In summary, existing technologies cannot solve core issues such as multi-unit synchronization and high-precision clock correction in SST, which restricts its stable application. Therefore, developing a suitable synchronization calibration method has become an urgent problem to be solved in this field. Summary of the Invention

[0007] This invention provides a synchronous calibration method and system for a modular solid-state transformer control device. This synchronous calibration method solves the technical problems of difficulty in synchronizing multiple unit modules and insufficient synchronization accuracy in the prior art, and achieves high-precision synchronization of power transmission operations between primary-side multi-level power units (primary-side controllers) and secondary-side power units (secondary-side controllers), ensuring stable system operation.

[0008] According to one aspect of the present invention, a synchronous calibration method for a modular solid-state transformer control device is provided, the modular solid-state transformer control device comprising a secondary-side controller and n primary-side controllers, where n is an integer greater than or equal to 1, the synchronous calibration method comprising: The secondary controller generates and broadcasts communication signals; The primary-side controller receives the communication signal, and each primary-side controller performs synchronization calibration based on the received communication signal, so that the control signal of the primary-side controller is synchronized with the control signal of the secondary-side controller.

[0009] Optionally, after the primary-side controller receives the communication signal, and each primary-side controller performs synchronization calibration based on the received communication signal to synchronize the control signal of the primary-side controller with the control signal of the secondary-side controller, the method further includes: The secondary controller monitors the synchronization status and controls the operation of the solid-state transformer based on the synchronization status.

[0010] Optionally, the secondary-side controller monitors the synchronization status and controls the operating status of the solid-state transformer according to the synchronization status, including: When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than a first threshold and less than a second threshold, the solid-state transformer is controlled to operate normally and a warning message is issued. When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than or equal to the second threshold and less than the third threshold, the solid-state transformer is controlled to operate at a 50% derating and is recalibrated synchronously. When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than or equal to the third threshold, the solid-state transformer is controlled to stop and a fault message is issued. Wherein, the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

[0011] Optionally, the secondary-side controller and the primary-side controller are connected via an optical fiber splitter. The secondary-side controller is connected to the input of the optical fiber splitter, and the n primary-side controllers are respectively connected to the n outputs of the optical fiber splitter. The secondary-side controller generates and broadcasts communication signals, including: The secondary side controller generates and sends a synchronization signal, sends a follow signal carrying the synchronization signal sending timestamp T1, receives the synchronization feedback signal from the primary side controller, and sends a signal carrying the synchronization feedback signal receiving timestamp T4. Each of the primary-side controllers performs synchronization calibration based on the received communication signal, including: Each primary-side controller independently performs a bidirectional calibration process to synchronize the control signals of the primary-side controller with those of the secondary-side controller.

[0012] Optionally, the bidirectional calibration process includes: The primary-side controller receives the synchronization signal sent by the secondary-side controller and records the first reception timestamp T2; The primary-side controller receives a follow signal carrying a synchronization signal transmission timestamp T1 sent by the secondary-side controller; The primary edge controller sends a synchronization feedback signal to the secondary edge controller and records the sending timestamp T3. The primary-side controller receives a signal carrying a synchronization feedback signal and a reception timestamp T4 sent by the secondary-side controller; The clock deviation Δt is calculated based on Δt=[(T2-T1)-(T4-T3)] / 2 to achieve synchronization between the primary controller and the secondary controller.

[0013] Optionally, n primary-side controllers are connected in series. The transmitting port of the secondary-side controller is connected to the receiving port of the first-level primary-side controller via optical fiber. The transmitting port of the previous-level primary-side controller is connected to the receiving port of the next-level primary-side controller via optical fiber. The transmitting port of the nth-level primary-side controller is connected to the receiving port of the secondary-side controller via optical fiber. The secondary-side controller generates and broadcasts communication signals, including: The secondary controller generates and sends a synchronization signal and a synchronization communication signal. The synchronization signal includes the rising edge, falling edge, or high / low level, or a preset width level of an independent electrical signal, and the initial rising edge, falling edge, or high / low level, or a preset width level of a communication data electrical signal. The synchronization communication signal carries a timestamp T0 indicating the time of transmission of the synchronization signal, and a timestamp T of the synchronization signal returned from the primary controller. 延迟 ; Each of the primary-side controllers performs synchronization calibration based on the received communication signal, including: Each primary-side controller performs calibration based on the acquisition timestamp T1 of its own synchronization signal and the transmission parameters in the synchronization communication data, thereby synchronizing the control signal of the primary-side controller with the control signal of the secondary-side controller.

[0014] Optionally, the synchronization signal is sent before the synchronization communication signal, and the process of the secondary controller generating and sending the synchronization signal includes: The secondary controller generates the synchronization signal, broadcasts it simultaneously to all primary controllers via optical fiber, and records the timestamp T0 of the synchronization signal transmission time. The synchronization signal is sequentially transmitted to the next-level primary edge controller via each of the primary edge controllers. The nth-level primary edge controller transmits the synchronization signal back to the secondary edge controller, which captures the returned synchronization signal and records the synchronization signal return timestamp T. 延迟 .

[0015] Optionally, the primary-side controller performs calibration based on the acquisition timestamp Tn of its synchronization signal and the transmission parameters in the synchronization communication data, including: The secondary controller uses the synchronization signal transmission timestamp T0 and the synchronization signal return timestamp T0 as the basis for the synchronization signal transmission timestamp. 延迟 And the number of primary-side controller cascade groups, calculate the average transmission delay time parameter d of each primary-side controller hardware: d=(T 延迟 -T0) / (n+1); The secondary controller generates a synchronization communication signal, which is broadcast sequentially to all the primary controllers via optical fiber. The synchronization communication signal includes the hardware average transmission delay time parameter d of each primary controller. Each primary-side controller captures a synchronization signal and records the capture timestamp Tn of the synchronization signal. The primary-side controller is then synchronized according to tn = Tn + n × d.

[0016] Optionally, the transmission period of the synchronization signal is an integer multiple of the power unit switching control period in the solid-state transformer.

[0017] According to another aspect of the present invention, a synchronous calibration system for a modular solid-state transformer control device is provided for performing the synchronous calibration method for the modular solid-state transformer control device described above.

[0018] The synchronous calibration method for a modular solid-state transformer control device provided in this invention is applicable to multi-modal solid-state transformer control devices comprising one secondary controller and n primary controllers. The secondary controller acts as the master controller, generating and broadcasting communication signals; the primary controllers act as slave controllers, receiving these communication signals. Each primary controller performs synchronous calibration based on the received communication signal, independently calculating the clock deviation and correcting the local control signal of the solid-state transformer. This ensures that the control signals of the secondary controller and primary controllers are synchronized, with the synchronization error stable within the range of 0-20 ns. This invention solves the technical problems of difficulty in multi-unit synchronization and insufficient synchronization accuracy in existing technologies, achieving high-precision synchronization of power transmission operations between primary-side multi-level power units (primary controllers) and secondary-side power units (secondary controllers), ensuring stable system operation.

[0019] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic block diagram of a medium-high voltage AC direct-connected DC module provided in an embodiment of the present invention; Figure 2 A schematic flowchart illustrating a synchronous calibration method for a modular solid-state transformer control device provided in an embodiment of the present invention; Figure 3 A schematic flowchart illustrating a synchronous calibration method for another modular solid-state transformer control device provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the architecture of a modular solid-state transformer control device provided in an embodiment of the present invention; Figure 5 A schematic diagram of the architecture of another modular solid-state transformer control device provided in an embodiment of the present invention; Figure 6 A flowchart illustrating the master-slave sequential transparent synchronization architecture provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of another medium-high voltage AC direct-connected DC module provided in an embodiment of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that the terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "above," "below," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "above" or "below" another element, it can be formed not only directly "above" or "below" the other element, but also indirectly "above" or "below" the other element through an intermediate element. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are only used to distinguish different components. It should be understood that such terms can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0024] Medium- and high-voltage direct-connected DC modules (Solid State Transformer, SST) are suitable for medium- and high-voltage direct-connected energy storage systems, electric vehicle charging facilities, and new energy grid connection, among other fields. For example... Figure 1 This is a schematic block diagram of a medium-high voltage AC direct-connected DC module provided in an embodiment of the present invention, with reference to... Figure 1The medium- and high-voltage AC direct-connect DC module is essentially an AC-DC converter, including AC input terminals (Ain1, Ain2) for connecting to the medium- and high-voltage AC power supply, DC output terminals (DCout+, DCout-), 2n sets of AC / AC modules (AC / AC module 1-1, AC / AC module 1-2~AC / AC module n-2), n sets of AC / DC modules (AC / DC module 1~AC / DC module n), and n sets of high-frequency transformers (B1~Bn). The input terminals of the 2n sets of AC / AC modules are connected in series between the AC input terminals. The output terminals of every two sets of AC / AC modules are connected to the two primary windings of one high-frequency transformer. Each high-frequency transformer has one secondary winding, and each secondary winding is connected to the AC terminal of one AC / DC module. The DC terminals of the AC / DC modules are connected in parallel to the DC output terminals of the medium- and high-voltage AC direct-connect DC module. The AC / DC module and the AC / AC module are respectively connected to the corresponding secondary-side controller and primary-side controller. In this embodiment, there is one secondary-side controller and n primary-side controllers (primary-side controller 1 to primary-side controller n). One secondary-side controller and n primary-side controllers form a control device for the solid-state transformer, which is used to calibrate the control signal, thereby correcting the local PWM control signal. The local PWM control signal controls the operation of the switching devices in the AC / AC module and the AC / DC module.

[0025] Figure 2 This is a flowchart illustrating a synchronous calibration method for a modular solid-state transformer control device provided in an embodiment of the present invention. The modular solid-state transformer control device includes one secondary-side controller and n primary-side controllers, where n is an integer greater than or equal to 1. The synchronous calibration method includes: S110, the secondary controller generates and broadcasts communication signals.

[0026] The embodiments of the present invention adopt a master-slave or master-multiple slave synchronous architecture. The following embodiments will be described using a master-multiple slave synchronous architecture as an example. The secondary controller (the control system center of the secondary power unit) acts as the master controller and can broadcast communication signals to all primary controllers (the control system center of the primary power unit) simultaneously or sequentially through optical fiber.

[0027] S120. The primary-side controller receives the communication signal. Each primary-side controller performs synchronization calibration based on the received communication signal, so that the control signal of the primary-side controller is synchronized with the control signal of the secondary-side controller.

[0028] After the secondary controller broadcasts the communication signal, the primary controller receives the communication signal sent by the secondary controller. Each primary controller independently performs synchronization calibration operation according to the communication signal and independently corrects its local clock. For example, when the secondary controller sends communication signals to all primary controllers at the same time, each primary controller communicates bidirectionally with the secondary controller and independently performs bidirectional calibration. When the secondary controller sends communication signals to the primary controllers in sequence, the fiber optic transmitting port of the last primary controller is connected to the fiber optic receiving port of the secondary controller to form a closed-loop communication link. The secondary controller transmits the communication signal to all primary controllers in sequence through the fiber optic cable. The hardware of the primary controller captures the communication signal and performs synchronization calibration operation to realize the synchronization calibration of the primary controller. The specific implementation method can be referred to in the following embodiment.

[0029] The technical solution of this invention can solve the technical problems of difficulty in synchronizing multiple units and insufficient synchronization accuracy in the prior art, and achieve high-precision synchronization of power transmission operations between primary-side multi-level power units (primary-side controller) and secondary-side power units (secondary-side controller), ensuring stable system operation.

[0030] Based on the above embodiments, Figure 3 This invention provides a schematic flowchart of a synchronization calibration method for a modular solid-state transformer control device. This embodiment monitors the synchronization error after synchronization, deeply integrates the synchronization status with system safety protection, and controls the operating status of the solid-state transformer based on the synchronization status. (Reference) Figure 3 The synchronous calibration method includes: S210, the secondary controller generates and broadcasts communication signals.

[0031] S220. The primary-side controller receives communication signals. Each primary-side controller performs synchronization calibration based on the received communication signals, so that the control signals of the primary-side controller are synchronized with the control signals of the secondary-side controller.

[0032] The S230 secondary controller monitors the synchronization status and controls the operation of the solid-state transformer based on the synchronization status.

[0033] Among them, a fault coordination module can be set in the secondary controller to monitor the synchronization status of the secondary controller and the primary controller. Specifically, multiple thresholds can be designed according to the synchronization status to control the solid-state transformer to work in different states.

[0034] In practice, optionally, the secondary controller monitors the synchronization status and controls the operating status of the solid-state transformer based on the synchronization status, including: When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than the first threshold and less than the second threshold, the solid-state transformer is controlled to operate normally and a warning message is issued; when the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than or equal to the second threshold and less than the third threshold, the solid-state transformer is controlled to operate at a 50% derating and is re-synchronized; when the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than or equal to the third threshold, the solid-state transformer is controlled to stop and a fault message is issued; wherein, the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

[0035] For example, in one embodiment, the first threshold is an alarm threshold, which can be 20ns; the second threshold is a power limiting threshold, which can be 40ns; and the third threshold is a protection threshold, which can be 60ns. This embodiment of the invention deeply integrates synchronization status with system safety protection. When the synchronization error is less than or equal to 20ns, the solid-state transformer is controlled to operate normally. When the synchronization error is greater than or equal to 20ns and less than 40ns, that is, when the alarm threshold is reached, a warning message is reported to the monitoring system, and the normal operation of the solid-state transformer is not interfered with. When the synchronization error is greater than or equal to 40ns and less than 60ns, that is, when the power limiting threshold is reached, the solid-state transformer is controlled to operate at a 50% derating rate and self-calibration is initiated. When the synchronization error is greater than 60ns, that is, when the protection threshold is reached, it indicates that the synchronization error is large and continued operation may damage the solid-state transformer. At this time, the machine is immediately stopped, the fault is reported, and the staff is reminded to carry out maintenance.

[0036] In one embodiment, n primary-side controllers can be connected in parallel, and the secondary-side controllers simultaneously broadcast communication signals to the n primary-side controllers. For example, Figure 4 A schematic diagram of the architecture of a modular solid-state transformer control device provided in this embodiment of the invention is shown below. Figure 4 Optionally, the secondary-side controller 10 and the primary-side controller 20 are connected via an optical fiber splitter 30. The input terminals of the secondary-side controller 10 and the optical fiber splitter 30 are connected, and the n primary-side controllers 20 are respectively connected to the n output terminals of the optical fiber splitter 30. In this embodiment, the secondary-side controller generates and broadcasts communication signals, including: generating and sending a synchronization signal, sending a follow signal carrying a synchronization signal transmission timestamp T1, receiving a synchronization feedback signal from the primary-side controller, and sending a signal carrying a synchronization feedback signal reception timestamp T4; wherein the secondary-side controller may include a clock generator, a synchronization signal generation module, and a timestamp management module, which respectively send or receive corresponding signals. Each primary-side controller performs synchronization calibration according to the received communication signal, including: each primary-side controller independently performs a bidirectional calibration process to synchronize the control signals of the primary-side controller and the secondary-side controller.

[0037] In this embodiment, the secondary controller acts as the primary controller, generating and sending a synchronization signal, which is simultaneously broadcast to all primary controllers via an optical fiber splitter. The transmission period of the synchronization signal is coupled with the power unit switching control period. The synchronization signal period is an integer multiple of the power unit switching control period. For example, the power unit switching control frequency can be f_sw=40kHz, the period T_sw=25μs, and the synchronization signal period can be T_sync=M×T_sw, where M is an integer. When M=2, T_sync=50μs.

[0038] Then each primary-side controller independently performs bidirectional calibration. Optionally, the bidirectional calibration process includes: The primary-side controller receives the synchronization signal sent by the secondary-side controller and records the first reception timestamp T2; The primary-side controller receives a follow signal carrying a synchronization signal transmission timestamp T1 sent by the secondary-side controller; The primary-side controller sends a synchronization feedback signal to the secondary-side controller and records the sending timestamp T3; The primary-side controller receives a signal carrying a synchronization feedback signal and a reception timestamp T4 sent by the secondary-side controller; The clock deviation Δt is calculated based on Δt=[(T2-T1)-(T4-T3)] / 2 to achieve synchronization between the primary and secondary controllers.

[0039] Each primary-side controller can communicate bidirectionally with the secondary-side controller and achieve independent calibration according to the above process. Each primary-side controller can calculate the communication transmission delay d1 and clock deviation Δt based on T1, T2, T3, and T4: d1=[(T2-T1)+(T4-T3)] / 2, Δt=[(T2-T1)-(T4-T3)] / 2. Each primary-side controller independently corrects its local clock based on the calculated clock deviation Δt to achieve synchronization with the secondary-side controller.

[0040] For example, in a specific embodiment, the parameters of the solid-state transformer are: the grid voltage is 10kV, the number of power units is 12, the switching frequency is 40kHz, the synchronization period is 50μs, the fiber length is 10mm~100mm, and the timestamp resolution is 10ns, so that the synchronization pulse is aligned with the PWM period, ensuring that the PWM carrier phase of each power unit is consistent at the synchronization moment.

[0041] This invention addresses the physical characteristics of optical fiber communication. During system initialization, it measures the bidirectional transmission delay of the optical fiber using a calibration mode and records the baseline value. It can also establish a temperature compensation model to monitor the ambient temperature of the optical fiber in real time, correct the transmission delay based on the temperature coefficient, and perform automatic calibration periodically (e.g., hourly) to compensate for long-term drift. This invention employs hardware timestamp capture with an operating frequency ≥100MHz and a timestamp resolution of 10ns. The timestamp is synchronized with the PWM cycle to ensure accurate execution of control commands. A dedicated hardware module handles the synchronization protocol, freeing up CPU resources.

[0042] In another embodiment, n primary-side controllers can be connected in series, and secondary-side controllers sequentially broadcast communication signals to the n primary-side controllers, forming a master-multiple-slave sequential transparent synchronization architecture. For example, Figure 5 A schematic diagram of another modular solid-state transformer control device provided in this embodiment of the invention is shown below. Figure 5 Optionally, n primary-side controllers 20 are connected in series. The transmitting port of the secondary-side controller 10 is connected to the receiving port of the first-level primary-side controller 20 via optical fiber. The transmitting port of the previous-level primary-side controller 20 is connected to the receiving port of the next-level primary-side controller 20 via optical fiber. The transmitting port of the nth-level primary-side controller 20 is connected to the receiving port of the secondary-side controller 10 via optical fiber. In this way, the optical fiber communication between the primary and secondary-side controllers forms a closed-loop communication link. The secondary-side controller generates and broadcasts communication signals, including: the secondary-side controller generates and transmits synchronization signals and synchronization communication signals. The synchronization signals include the rising edge, falling edge, or high level, low level, or preset width level of an independent electrical signal, and the starting rising edge, falling edge, or high level, low level, or preset width level of the communication data electrical signal. The synchronization communication signal carries a synchronization signal transmission time stamp T0 to capture the synchronization signal return time stamp T returned from the primary-side controller. 延迟 The secondary-side controller may include a clock generator, a synchronization signal generation module, and a timestamp management module, which respectively send or receive corresponding signals. The secondary-side controller transmits the communication signals sequentially to all primary-side controllers via optical fiber. The primary-side controllers capture the synchronization signals and perform synchronization calibration, thus achieving synchronization calibration between the primary and secondary-side controllers. Each primary-side controller performs synchronization calibration based on the received communication signals, including: Each primary-side controller performs calibration based on the acquisition timestamp Tn of its own synchronization signal and the transmission parameters in the synchronization communication data, thereby synchronizing the control signals of the primary-side controller with those of the secondary-side controller.

[0043] Optionally, the synchronization signal is sent before the synchronization communication signal. The process of the secondary controller generating and sending the synchronization signal includes: The secondary controller generates a synchronization signal, which is simultaneously broadcast to all primary controllers via optical fiber, and records the timestamp T0 of the synchronization signal transmission time. The synchronization signal is sequentially transmitted from each primary-side controller to the next primary-side controller. The nth primary-side controller transmits the synchronization signal back to the secondary-side controller. The secondary-side controller captures the returned synchronization signal and records the synchronization signal return timestamp T. 延迟 .

[0044] Optionally, the primary-side controller performs calibration based on the acquisition timestamp Tn of its synchronization signal and the transmission parameters in the synchronization communication data, including: The secondary controller sends a time stamp T0 based on the synchronization signal and returns a time stamp T. 延迟 And the number of primary-side controller cascade groups, calculate the average transmission delay time parameter d of each primary-side controller hardware: d=(T 延迟 -T0) / (n+1); The secondary controller generates a synchronization communication signal, which is broadcast sequentially to all primary controllers via optical fiber. The synchronization communication signal includes the average transmission delay time parameter d of the hardware of each primary controller. Each primary-side controller captures the synchronization signal and records the capture timestamp Tn. The primary-side controller is then synchronized according to tn=Tn+n×d.

[0045] In this embodiment, the secondary controller acts as the primary controller, generating and sending a synchronization signal, which is then sequentially sent to all primary controllers. The transmission period of the synchronization signal is coupled with the power unit switching control period. The synchronization signal period is an integer multiple of the power unit switching control period. For example, the power unit switching control frequency can be f_sw=40kHz, the period T_sw=25μs, and the synchronization signal period can be T_sync=M×T_sw, where M is an integer. When M=2, T_sync=50μs.

[0046] Figure 6 This is a flowchart illustrating a master-slave sequential transparent synchronization architecture provided in an embodiment of the present invention. (Refer to...) Figure 6 At the start of synchronization, determine whether the secondary controller has captured the synchronization signal and returned a timestamp T. 延迟 Since the secondary controller has not yet sent a synchronization signal, the result is negative at this point (i.e., the synchronization signal is sent before the synchronization communication signal), and execution is performed. Figure 6In the left-hand flow, the secondary controller, acting as the primary controller, generates a synchronization signal, broadcasts it to the primary controller via fiber optic cable, and records the timestamp T0 of the synchronization signal transmission from primary controller n. The synchronization signal is then sequentially passed through each primary controller to the next level, with the final (nth) primary controller transmitting the synchronization signal back to the secondary controller. The secondary controller's hardware captures the returned synchronization signal and records the timestamp T of the return signal. 延迟 Then determine whether the secondary controller has captured the synchronization signal and returned the timestamp T. 延迟 At this time, it is determined to be yes, and execution is performed. Figure 6 In the right-hand part of the process, the secondary controller sends a time stamp T0 based on the synchronization signal and returns a time stamp T based on the synchronization signal. 延迟 And the number of cascaded primary-side controllers in the entire system, calculate the hardware transmission delay Δt1 of the entire communication link and the hardware transmission delay time parameter d of a single primary-side controller: Δt1=T 延迟 -T0; d=Δt1 / (n+1), that is, d=(T 延迟 -T0) / (n+1). The secondary controller, acting as the primary controller, generates a synchronization communication signal based on the hardware transmission delay time parameter d of the single-level controller and broadcasts it sequentially to all primary controllers via optical fiber. Each primary controller hardware captures the synchronization signal and records the capture timestamp Tn, while simultaneously receiving the transmission parameter d from the synchronization communication data. Based on the capture timestamp Tn of the local synchronization signal, n×d is added as the correction parameter time for hardware synchronization delay compensation, i.e., Tn+n×d, to perform PWM synchronization calibration on the local primary controller. n is the sequential number of the multi-level series connection position, with the first primary controller connected to the secondary controller being 1, and so on. When the difference between the local PWM timing signal and the captured synchronization calibration time (after compensation) is continuously <20ns, the synchronization calibration is considered successful, and a synchronization success signal is sent to the secondary controller. When the secondary controller receives calibration completion signals from all primary controllers, it is determined that the entire system has completed high-precision synchronization calibration <20ns.

[0047] This invention addresses the hardware physical delay characteristics of synchronous communication signals based on the consistent communication receiving and transmitting hardware processing of each controller, small ambient temperature deviation within the module chassis, and inherently low hardware delay (nanosecond level). Therefore, this compensation method can be applied to each controller. The embodiments of the present invention can use a DSP to implement hardware timestamp capture. The DSP operates at a frequency of ≥100MHz and has a timestamp resolution of 10ns. The timestamp is synchronized with the PWM cycle to ensure the accurate execution of control instructions. A dedicated hardware module handles the synchronization protocol, freeing up CPU resources.

[0048] Table 1 below shows a comparison of the effects of the embodiments of the present invention with those of the prior art: Table 1. Comparison of the effects of the embodiments of the present invention with those of the prior art. The synchronization calibration method for the modular solid-state transformer control device provided in this invention adopts a master-slave synchronization architecture: the secondary controller acts as the master controller, and the primary controller acts as the slave controller. The secondary controller sends synchronization signals to all primary controllers; each primary controller independently performs synchronization calibration operations based on the synchronization signals, independently correcting its local clock. This invention deeply couples the synchronization period with the switching frequency (the synchronization period is an integer multiple of the switching frequency), uses hardware to capture the synchronization signal (10ns resolution), and sets three threshold levels (20ns / 40ns / 60ns) to achieve synchronization status monitoring and fault protection linkage. This invention solves technical problems such as difficulty in synchronizing multiple power units, inability to compensate for clock deviations, and insufficient synchronization accuracy. The synchronization error is less than 20ns, making it suitable for medium- and high-voltage direct-connected energy storage systems, electric vehicle charging facilities, and new energy grid connection.

[0049] The synchronous calibration method provided in this invention is applicable not only to Figure 1 The solid-state transformer structure shown is also applicable to other structures, for example... Figure 7 A schematic diagram of another medium-high voltage AC direct-connected DC module provided in an embodiment of the present invention is shown below. Figure 7 Its and Figure 1 The differences between the medium and high voltage AC direct-connected DC modules shown are: 1. Figure 1 There are n sets of high-frequency transformers, and Figure 7 1. There is one set of high-frequency transformers; 2. Figure 1 Each high-frequency transformer shown has two primary windings. Figure 7 The high-frequency transformer has 2n sets of primary windings; 3. Figure 1 The 2n AC / AC modules shown are connected to the primary windings of n high-frequency transformers. Figure 7 All AC / AC modules are connected to the primary winding of the same high-frequency transformer; 4. Figure 1 The secondary windings of the n high-frequency transformers shown are connected to n AC / DC modules. Figure 7 There is only one set of secondary windings connected to one set of AC / DC modules. The specific implementation is that the structure of the solid-state transformer can be designed according to the actual situation. As long as there is a master-slave structure with one secondary controller and n primary controllers, it is applicable.

[0050] This invention also provides a synchronous calibration system for a modular solid-state transformer control device, used to execute any of the synchronous calibration methods for the modular solid-state transformer control device provided in the above embodiments.

[0051] Since the synchronous calibration system for the solid-state transformer control device provided in this embodiment of the invention is used to execute any of the synchronous calibration methods for the modular solid-state transformer control device provided in the above embodiments, and has the same or corresponding technical effects, it will not be described in detail here.

[0052] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A synchronous calibration method for a modular solid-state transformer control device, characterized in that, The modular solid-state transformer control device includes one secondary-side controller and n primary-side controllers, where n is an integer greater than or equal to 1. The synchronization calibration method includes: The secondary controller generates and broadcasts communication signals; The primary-side controller receives the communication signal, and each primary-side controller performs synchronization calibration based on the received communication signal, so that the control signal of the primary-side controller is synchronized with the control signal of the secondary-side controller.

2. The synchronous calibration method for the modular solid-state transformer control device according to claim 1, characterized in that, After the primary-side controller receives the communication signal, and each primary-side controller performs synchronization calibration based on the received communication signal to synchronize the control signal of the primary-side controller with the control signal of the secondary-side controller, the process further includes: The secondary controller monitors the synchronization status and controls the operation of the solid-state transformer based on the synchronization status.

3. The synchronous calibration method for the modular solid-state transformer control device according to claim 2, characterized in that, The secondary-side controller monitors the synchronization status and controls the operating status of the solid-state transformer based on the synchronization status, including: When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than a first threshold and less than a second threshold, the solid-state transformer is controlled to operate normally and a warning message is issued. When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than or equal to the second threshold and less than the third threshold, the solid-state transformer is controlled to operate at a 50% derating and is recalibrated synchronously. When the difference between the control signal of the secondary controller and the control signal of the primary controller is greater than or equal to the third threshold, the solid-state transformer is controlled to stop and a fault message is issued. Wherein, the first threshold is less than the second threshold, and the second threshold is less than the third threshold.

4. The synchronous calibration method for the modular solid-state transformer control device according to claim 1, characterized in that, The secondary-side controller and the primary-side controller are connected via an optical fiber splitter. The secondary-side controller is connected to the input end of the optical fiber splitter, and the n primary-side controllers are respectively connected to the n output ends of the optical fiber splitter. The secondary controller generates and broadcasts communication signals, including: The secondary side controller generates and sends a synchronization signal, sends a follow signal carrying the synchronization signal sending timestamp T1, receives the synchronization feedback signal from the primary side controller, and sends a signal carrying the synchronization feedback signal receiving timestamp T4. Each of the primary-side controllers performs synchronization calibration based on the received communication signal, including: Each primary-side controller independently performs a bidirectional calibration process to synchronize the control signals of the primary-side controller with those of the secondary-side controller.

5. The synchronous calibration method for the modular solid-state transformer control device according to claim 4, characterized in that, The bidirectional calibration process includes: The primary-side controller receives the synchronization signal sent by the secondary-side controller and records the first reception timestamp T2; The primary-side controller receives a follow signal carrying a synchronization signal transmission timestamp T1 sent by the secondary-side controller; The primary edge controller sends a synchronization feedback signal to the secondary edge controller and records the sending timestamp T3; The primary-side controller receives a signal carrying a synchronization feedback signal and a reception timestamp T4 sent by the secondary-side controller; The clock deviation Δt is calculated based on Δt=[(T2-T1)-(T4-T3)] / 2 to achieve synchronization between the primary controller and the secondary controller.

6. The synchronous calibration method for the modular solid-state transformer control device according to claim 1, characterized in that, The n primary-side controllers are connected in series. The transmitting port of the secondary-side controller is connected to the receiving port of the first-level primary-side controller via optical fiber. The transmitting port of the previous-level primary-side controller is connected to the receiving port of the next-level primary-side controller via optical fiber. The transmitting port of the nth-level primary-side controller is connected to the receiving port of the secondary-side controller via optical fiber. The secondary-side controller generates and broadcasts communication signals, including: The secondary controller generates and sends a synchronization signal and a synchronization communication signal. The synchronization signal includes the rising edge, falling edge, or high / low level, or a preset width level of an independent electrical signal, and the initial rising edge, falling edge, or high / low level, or a preset width level of a communication data electrical signal. The synchronization communication signal carries a timestamp T0 indicating the time of transmission of the synchronization signal and a timestamp T of the synchronization signal returned from the primary controller. 延迟 ; Each of the primary-side controllers performs synchronization calibration based on the received communication signal, including: Each primary-side controller performs calibration based on the acquisition timestamp Tn of its own synchronization signal and the transmission parameters in the synchronization communication data, thereby synchronizing the control signal of the primary-side controller with the control signal of the secondary-side controller.

7. The synchronous calibration method for the modular solid-state transformer control device according to claim 6, characterized in that, The synchronization signal is sent before the synchronization communication signal, and the process by which the secondary controller generates and sends the synchronization signal includes: The secondary controller generates the synchronization signal, broadcasts it simultaneously to all primary controllers via optical fiber, and records the timestamp T0 of the synchronization signal transmission time. The synchronization signal is sequentially transmitted to the next-level primary edge controller via each of the primary edge controllers. The nth-level primary edge controller transmits the synchronization signal back to the secondary edge controller, which captures the returned synchronization signal and records the synchronization signal return timestamp T. 延迟 .

8. The synchronous calibration method for the modular solid-state transformer control device according to claim 7, characterized in that, The primary-side controller performs calibration based on the acquisition timestamp Tn of its synchronization signal and the transmission parameters in the synchronization communication data, including: The secondary controller uses the synchronization signal transmission timestamp T0 and the synchronization signal return timestamp T0 as the basis for the synchronization signal transmission timestamp. 延迟 And the number of primary-side controller cascade groups, calculate the average transmission delay time parameter d of each primary-side controller hardware: d=(T 延迟 -T0) / (n+1); The secondary controller generates a synchronization communication signal, which is broadcast sequentially to all the primary controllers via optical fiber. The synchronization communication signal includes the hardware average transmission delay time parameter d of each primary controller. Each primary-side controller captures a synchronization signal and records the capture timestamp Tn of the synchronization signal. The primary-side controller is then synchronized according to tn = Tn + n × d.

9. The synchronous calibration method for the modular solid-state transformer control device according to claim 4 or 6, characterized in that, The transmission period of the synchronization signal is an integer multiple of the switching control period of the power unit in the solid-state transformer.

10. A synchronous calibration system for a modular solid-state transformer control device, characterized in that, Synchronous calibration method for performing the modular solid-state transformer control device according to any one of claims 1 to 9.

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