A carrier synchronization control method for multiple converters

Abstract

The application discloses a carrier synchronous control method of multiple converters, wherein each converter corresponds to an independent controller, the controllers are set as one master and multiple slaves, optical fiber connection from the master controller to each slave controller is established, or a communication architecture of full-duplex optical fiber communication between each two of the multiple controllers is established; when the controllers are set as one master and multiple slaves, the corresponding carrier synchronous control method comprises the following steps: the master controller outputs a carrier synchronous signal to each slave controller; after receiving the carrier synchronous signal of the master controller, each slave controller reloads the carrier initial value and the carrier initial direction, and reinitializes the carrier, so as to realize carrier synchronization or phase difference between the master controller and the slave controllers. The application can realize carrier synchronization of multiple converters, realize pulse approximation consistency, prevent large zero sequence current from causing out-of-control, realize carrier strict phase difference of multiple converters, realize ripple cancellation, and improve output performance.

Description

Technical Field

[0001] This invention mainly relates to the field of converter technology, and specifically to a carrier synchronization control method for multiple converters. Background Technology

[0002] The wind-solar-hydrogen storage industry is developing rapidly and is moving towards higher power, larger capacity, and larger scale. Among them, the inverter, as an important component of the wind-solar-hydrogen storage system, is one of the main ways to achieve high power and large capacity through parallel application, thereby realizing the trend of large-scale development of wind-solar-hydrogen storage systems.

[0003] In wind power systems, the common converter topology is AC / DC / AC, with the first AC side connected to the grid via a transformer and the second AC side connected to the wind turbine generator. In photovoltaic systems, the common converter topology is AC / DC or AC / DC / DC, with the AC side connected to the grid via a transformer and the DC side directly or indirectly connected to the photovoltaic modules. In energy storage systems, the common converter topology is AC / DC or AC / DC / DC, with the AC side connected to the grid via a transformer and the DC side connected to energy storage carriers such as batteries and supercapacitors. In hydrogen production systems, the common converter topology is AC / DC or AC / DC / DC, with the AC side connected to the grid via a transformer and the DC side connected to the electrolyzer.

[0004] To reduce system costs, especially grid-connected transformer costs, the above systems often use multiple parallel connections of AC / DC converters to achieve high-power solutions. This often abandons the traditional approach of parallel connection on the DC side and independent transformer windings on the AC side, instead adopting a method where both AC and DC sides are directly paralleled, with the AC side connected to a single transformer winding. While this approach reduces the design and manufacturing complexity and cost of the grid-connected transformer, it presents significant challenges to the coordinated control of the independently controlled AC / DC converters within the parallel system. The clock differences of independent controllers make it difficult to naturally maintain near-consistency of the drive pulses of each AC / DC converter. If the drive pulse differences between the parallel AC / DC converters are large and the system's zero-sequence impedance is low, a large zero-sequence circulating current will be generated. This can range from affecting the normal power output of the converters to causing control loop failure, leading to overvoltage and overcurrent faults.

[0005] In the above systems, when multiple DC / DC converters are connected in parallel to achieve a high-power solution, phase-shift control is often used to further improve the DC-side output performance or reduce costs. However, the clock differences of the independent controllers make it difficult to naturally maintain a strict phase-shift angle for the drive pulses of each DC / DC converter, causing phase-shift failure, affecting DC output performance, and failing to guarantee the cancellation of current ripple between parallel branches to achieve better output current ripple performance.

[0006] Conventional synchronous SPWM modulation maintains a carrier frequency that is a fixed multiple of the AC voltage phase-locked loop frequency (power frequency). Each controller locks onto the same AC voltage, and the phase of the phase-locked AC voltage over the entire power frequency cycle is then divided equally by a fixed multiple. Each segment after division constitutes one carrier cycle, achieving carrier generation for each controller and carrier synchronization between multiple controllers. However, the program cycle of the limited phase-locked loop controller chip is not very small (it is difficult to reach the nanosecond or tens of nanosecond levels), typically ranging from microseconds to hundreds of microseconds. Therefore, there are certain differences in the real-time phase of the AC voltage locked by each controller. These differences have a low impact on carrier synchronization at lower switching frequencies (lower division multiples), and the basic carrier synchronization performance between multiple controllers is guaranteed, so this difference can be ignored. However, at higher switching frequencies (kHz or above 10kHz), the difference in carrier synchronization becomes significant. At this point, carrier consistency synchronization of multiple AC / DC converters or carrier phase missynchronization synchronization of multiple DC / DC converters cannot be guaranteed, leading to adverse effects such as zero-sequence circulating current or phase missynchronization failure. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: in view of the technical problems existing in the prior art, the present invention provides a carrier synchronization control method for multiple converters to achieve carrier synchronization to prevent runaway caused by large zero-sequence current, and to achieve strict phase misalignment of multiple converter carriers to achieve ripple cancellation.

[0008] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0009] A carrier synchronization control method for multiple converters, wherein each converter has a corresponding controller, and each controller is configured as one master and multiple slaves, and the master controller and each slave controller are connected by optical fiber; or the multiple controllers establish mutual full-duplex optical fiber communication between each other, and the multiple controllers can freely select any one of them as the master controller and the others as slave controllers.

[0010] When the controllers are configured as one master and multiple slaves, the corresponding carrier synchronization control method includes the following steps:

[0011] The master controller outputs a carrier synchronization signal to each slave controller based on the carrier peak or carrier trough flags during its own carrier generation process.

[0012] After receiving the carrier synchronization signal from the master controller, the slave controller reloads its initial carrier value and initial carrier direction, and reinitializes the carrier to achieve carrier consistency synchronization or phase missynchronization between the master controller and the slave controller.

[0013] Preferably, when establishing pairwise full-duplex optical fiber communication between multiple controllers, the carrier synchronization control method for each controller includes the following steps:

[0014] Each controller outputs a carrier peak flag and a carrier trough flag, and then outputs a carrier synchronization signal based on the carrier peak and carrier trough flags. This signal is then ANDed with the master-slave flag signal of the current controller before being output to other controllers. Each controller performs an OR operation on the multiple received carrier synchronization signals, and then performs an AND operation with the inverted master-slave flag signal of the current controller to obtain the final carrier synchronization signal to control carrier generation. In the master-slave flag signal, master is 1 and slave is 0.

[0015] Preferably, when the carrier wave is in a triangular configuration, the specific process of the main controller outputting the carrier synchronization signal is as follows:

[0016] Load the initial carrier value and initial carrier direction; where the initial carrier value and initial carrier direction are the carrier value and carrier direction of the first clock cycle after the carrier is enabled.

[0017] Determine the carrier direction: When the carrier direction increases, the carrier value is incremented by 1. If the actual carrier value reaches its peak value after incrementing by 1, the carrier direction changes to decrease, a carrier peak flag is output, and the process returns to the carrier direction determination stage. If the actual carrier value does not reach its peak value after incrementing by 1, the process directly returns to the carrier direction determination stage and continues to the next determination stage.

[0018] When the carrier direction decreases, the carrier value is -1. If the actual carrier value after -1 reaches 0, the carrier direction becomes increasing, and a carrier trough flag is output. Then, the process returns to the carrier direction determination stage. If the actual carrier value after -1 does not reach 0, the process directly returns to the carrier direction determination stage and continues to the next determination stage.

[0019] The master controller outputs a carrier synchronization signal to the slave controller at the carrier peak or carrier trough marker.

[0020] Preferably, when the carrier configuration is triangular, the specific process of generating and applying the input carrier synchronization signal from the corresponding carrier in the controller is as follows:

[0021] Load the initial carrier value and initial carrier direction; where the initial carrier value and initial carrier direction are the carrier value and carrier direction of the first clock cycle after the carrier is enabled.

[0022] Determine the carrier direction: When the carrier direction increases, the carrier value is incremented by 1. If the actual carrier value reaches its peak value after incrementing by 1, the carrier direction changes to decrease, a carrier peak flag is output, and the process returns to the carrier direction determination stage. If the actual carrier value does not reach its peak value after incrementing by 1, the process directly returns to the carrier direction determination stage and continues to the next determination stage.

[0023] When the carrier direction decreases, the carrier value is -1. If the actual carrier value after -1 reaches 0, the carrier direction becomes increasing, and a carrier trough flag is output. Then, the process returns to the carrier direction determination stage. If the actual carrier value after -1 does not reach 0, the process directly returns to the carrier direction determination stage and continues to the next determination stage.

[0024] When the controller receives the carrier synchronization signal from the main controller in real time, it directly returns to the step of loading the initial carrier value and the initial carrier direction.

[0025] Finally, a carrier signal synchronized with the main controller is generated.

[0026] Preferably, when the carrier mode is a sawtooth wave, the specific process of the main controller outputting the carrier synchronization signal is as follows:

[0027] The carrier direction is determined. When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is incremented by 1. If the actual carrier value after incrementing by 1 reaches the peak value, the carrier value is directly changed to 0, and the carrier peak-valley flag is output. Then, the process returns to the carrier value incrementing step. If the actual carrier value after incrementing by 1 does not reach the peak value, the process returns directly to the carrier value incrementing step and continues to the next step. The initial carrier value is the carrier value of the first step after the carrier is enabled.

[0028] When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is decremented by 1. If the actual carrier value after decrementing by 1 reaches 0, the carrier value directly becomes the peak value, and the carrier peak-valley flag is output. Then, the process returns to the carrier value decrementing step. If the actual carrier value after decrementing by 1 does not reach 0, the process returns directly to the carrier value decrementing step and continues to the next step for judgment.

[0029] The master controller outputs a carrier synchronization signal to the slave controller at the carrier peak or carrier trough marker.

[0030] Preferably, when the carrier mode is a sawtooth wave, the specific process of generating and applying the input carrier synchronization signal from the controller corresponding to the carrier is as follows:

[0031] The carrier direction is determined. When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is incremented by 1. If the actual carrier value after incrementing by 1 reaches the peak value, the carrier value is directly changed to 0, and the carrier peak-valley flag is output. Then, the process returns to the carrier value incrementing step. If the actual carrier value after incrementing by 1 does not reach the peak value, the process returns directly to the carrier value incrementing step and continues to the next step. The initial carrier value is the carrier value of the first step after the carrier is enabled.

[0032] When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is decremented by 1. If the actual carrier value after decrementing by 1 reaches 0, the carrier value directly becomes the peak value, and the carrier peak-valley flag is output. Then, the process returns to the carrier value decrementing step. If the actual carrier value after decrementing by 1 does not reach 0, the process returns directly to the carrier value decrementing step and continues to the next step for judgment.

[0033] When the controller receives the carrier synchronization signal from the main controller in real time, it directly returns to the step of loading the initial carrier value.

[0034] Finally, a carrier signal synchronized with the main controller is generated.

[0035] Preferably, when each converter is an AC / DC converter and the AC and DC sides are directly connected in parallel, the carrier consistency synchronization between the master controller and the slave controller is achieved.

[0036] Preferably, the carrier mode is a triangular wave. When the master controller outputs a carrier synchronization signal to the slave controller at the carrier wave trough, and the initial carrier value of each slave controller is set to 0, the carrier consistency synchronization between the master controller and the slave controller is achieved. When the master controller outputs a carrier synchronization signal to the slave controller at the carrier wave peak, and the initial carrier value of each slave controller is set to the carrier wave peak value, the carrier consistency synchronization between the master controller and the slave controller is also achieved.

[0037] Preferably, when each converter is a DC / DC converter and the input and output sides are directly connected in parallel, the carrier phase misalignment synchronization between the master controller and the slave controller is achieved.

[0038] Preferably, the carrier mode is a sawtooth wave. When the master controller outputs a carrier synchronization signal to the slave controller at the carrier trough or peak, and the initial carrier value of each slave controller is set to a multiple of 1 / n, 2 / n, ..., (n-1) / n of the carrier peak value, strict phase-out synchronization of the carriers among multiple controllers is achieved; where n is a natural number greater than 1.

[0039] Preferably, carrier generation and synchronization control are performed on a chip with a high-speed clock in the controller.

[0040] Compared with the prior art, the advantages of the present invention are as follows:

[0041] The multi-converter carrier synchronization control method of the present invention can realize the carrier synchronization of multiple converters, thereby achieving pulse approximate consistency and preventing runaway caused by large zero-sequence current. It can also achieve strict phase misalignment of multiple converter carriers, realize ripple cancellation, and improve output performance.

[0042] The independent controller of the multi-converter in this invention uses high-speed fiber optic communication for synchronization, and carrier generation and synchronization control are executed on a control chip with a high-speed clock, without relying on a phase-locked loop (PLL) controller. Differences in the PLL controller's program cycle have no impact on carrier generation. Although a high-speed fiber optic interface is required, true carrier synchronization (whether for carrier consistency synchronization of multiple AC / DC converters or carrier phase misalignment synchronization of multiple DC / DC converters) can be achieved, thereby avoiding carrier synchronization differences caused by PLL controller program cycle differences and the resulting adverse effects of zero-sequence circulating current or phase misalignment failures. Attached Figure Description

[0043] Figure 1 This is a diagram showing the topology and controller communication architecture of the multi-converter independent control parallel system of the present invention.

[0044] Figure 2 This is a flowchart of the main controller carrier generation and carrier synchronization signal output of the present invention.

[0045] Figure 3 This is a flowchart of the controller carrier generation and carrier synchronization control process of the present invention.

[0046] Figure 4 This is a flowchart of the master-slave controller compatible carrier generation and carrier synchronization control of the present invention. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0048] In the carrier synchronization control method for multiple converters in this embodiment of the invention, the corresponding multiple converter is as follows: Figure 1 As shown, this is specifically applied in hydrogen production power sources, etc. Converter 1, Converter 2, ..., Converter n can be either an AC / DC topology or an AC / DC / DC topology, controlled by the corresponding numbered controller. The controllers form a master-slave high-speed communication architecture, with controller 1 as the master and the other controllers as slaves. The master communicates with the slaves via high-speed communication, typically using fiber optic communication. Where n ≥ 2. Based on the above hardware, each controller achieves carrier synchronization and pulse consistency in carrier generation and pulse modulation using the following methods:

[0049] The master controller outputs a carrier synchronization signal to each slave controller based on the carrier peak or carrier trough flags during its own carrier generation process.

[0050] After receiving the carrier synchronization signal from the master controller, the slave controller reloads its initial carrier value and initial carrier direction, and reinitializes the carrier to achieve carrier consistency synchronization or phase missynchronization between the master controller and the slave controller.

[0051] The independent controllers of the aforementioned multi-converter employ high-speed fiber optic communication for synchronization, and carrier generation and synchronization control are executed on a chip with a high-speed clock, independent of the phase-locked loop (PLL) controller. Differences in the PLL controller's program cycle have no impact on carrier generation. Although a high-speed fiber optic interface is required, true carrier synchronization (whether for carrier consistency synchronization of multiple AC / DC converters or carrier phase misalignment synchronization of multiple DC / DC converters) can be achieved. This avoids carrier synchronization differences caused by PLL controller program cycle variations and the resulting adverse effects of zero-sequence circulating current or phase misalignment failures.

[0052] The above carrier synchronization control method is as follows: Figure 2 As shown:

[0053] After receiving a valid carrier enable signal, the main controller loads the carrier peak value and carrier mode.

[0054] Determine the carrier mode: When the carrier mode is triangular wave mode, continue to load the initial carrier value and initial carrier direction, where the initial carrier value and initial carrier direction are the carrier value and carrier direction of the first step after the carrier is enabled;

[0055] Next, determine the carrier direction: when the carrier direction increases, the carrier value is incremented by 1. If the actual carrier value reaches its peak value after incrementing by 1, the carrier direction changes to decrease, and a carrier peak flag is output. Then, return to the carrier direction determination stage. If the actual carrier value does not reach its peak value after incrementing by 1, return directly to the carrier direction determination stage and continue to the next determination.

[0056] When the carrier direction decreases, the carrier value is -1. If the actual carrier value reaches 0 after -1, the carrier direction becomes increasing, and a carrier trough flag is output. Then, the process returns to the carrier direction judgment stage. If the actual carrier value does not reach 0 after -1, the process directly returns to the carrier direction judgment stage and continues to the next judgment.

[0057] When the carrier mode is sawtooth wave mode, carrier direction determination is performed: When it is an increasing sawtooth wave, the initial carrier value is loaded again, which is the carrier value of the first cycle after the carrier enable is effective; then the carrier value is incremented by 1. If the actual carrier value reaches the peak value after incrementing by 1, the carrier value directly becomes 0, and the carrier peak-valley flag is output, and then the process returns to the carrier value incrementing step; if the actual carrier value does not reach the peak value after incrementing by 1, the process returns directly to the carrier value incrementing step and continues to the next cycle determination; When it is a decreasing sawtooth wave, the initial carrier value is loaded again, which is the carrier value of the first cycle after the carrier enable is effective, and then the carrier value is decremented by 1. If the actual carrier value reaches 0 after decrementing by 1, the carrier value directly becomes the peak value, and the carrier peak-valley flag is output, and then the process returns to the carrier value decrementing step; if the actual carrier value does not reach 0 after decrementing by 1, the process returns directly to the carrier value decrementing step and continues to the next cycle determination.

[0058] Regardless of the carrier mode, the master controller outputs the required carrier synchronization signal to the high-speed communication (fiber optic) output port based on the carrier peak or trough markers, and then transmits it to each slave controller via high-speed (fiber optic) communication. The above carrier synchronization signal generation method is simple to operate and easy to implement.

[0059] The carrier generation control of the controller is basically the same as that of the main controller, such as... Figure 3 As shown, the difference lies in that after the carrier startup enable is effective, the carrier outputs a carrier synchronization signal in the same way that the main controller generates the carrier. If an externally input carrier synchronization signal is received at any time, the carrier value and carrier direction are reloaded with the initial carrier value and initial carrier direction, and the carrier is reinitialized. Similarly, external inputs such as carrier synchronization signals are input through a high-speed communication (fiber optic) input port.

[0060] The carrier synchronization signal output by the main controller and the carrier synchronization signal input by the slave controller can be either level signals or edge signals. In actual use, edge signals are less affected by communication transmission and are more commonly used.

[0061] In one specific embodiment, when each converter is an AC / DC converter, the carrier synchronization between the master controller and the slave controller is achieved. Specifically, the carrier mode is a triangular wave. When the master controller outputs a carrier synchronization signal to the slave controller at a carrier trough, and the initial carrier value of each slave controller is set to 0, carrier synchronization between the master and slave controllers can be achieved. Similarly, when the master controller outputs a carrier synchronization signal to the slave controller at a carrier peak, and the initial carrier value of each slave controller is set to the carrier peak value, carrier synchronization between the master and slave controllers can also be achieved. Regardless of the mode, while achieving carrier synchronization, the multiple AC / DC converters have the same control objective and control parameters, and the electrical parameters of the multiple converter circuits are also the same. The modulation waves output by the closed-loop control are approximately consistent, and after comparison with the carrier wave that has completed the synchronization process, the pulses are approximately consistent.

[0062] When multiple AC / DC converters are directly connected in parallel on the AC and DC sides, the carrier consistency synchronization control of multiple converters is used to achieve pulse approximate consistency. This not only enables the parallel system to increase power, capacity and scale, but also suppresses the generation of large zero-sequence circulating current, increases the stability of system operation, prevents overvoltage and overcurrent faults caused by control loop failure, and protects the converter from zero-sequence current pressure, thus avoiding power loss of the converter output.

[0063] In each DC / DC converter, the carrier phase misalignment synchronization between the master controller and the slave controller is achieved. Specifically, the carrier mode is a sawtooth wave. When the master controller outputs a carrier synchronization signal to the slave controller at the carrier trough or peak, and the initial carrier value of each slave controller is set to a multiple of 1 / n, 2 / n, ..., (n-1) / n of the carrier peak value, strict phase misalignment of the multiple controller carriers can be achieved. When the modulation waves (or duty cycles) are equal or approximately equal, strict phase misalignment of the pulses is achieved, realizing phase misalignment harmonic cancellation or ripple reduction effect.

[0064] When multiple DC / DC converters are directly connected in parallel, the carrier phase reversal synchronization control of the multiple converters achieves strict pulse phase reversal. This not only enables the parallel system to increase power, capacity, and scale, but also allows multiple phase reversals to cancel ripple, resulting in better output current ripple performance. If the existing output current ripple performance is maintained, the volume and cost of chopper reactors and other components can be significantly reduced, and the power density of the converter can be increased.

[0065] High-speed fiber optic communication must meet the requirement of high-speed communication rate. Under the current industry technology background, the underlying controller (usually FPGA, CPLD or DSP, MCU) that processes carrier control and PWM modulation algorithm has a high clock frequency, and high-speed communication meets the requirements of baud rate above 1Mbps and bandwidth above 1MHz.

[0066] If the parallel system has sufficient fiber optic interface resources or other high-speed digital communication interface resources for each controller, a communication architecture for full-duplex communication between multiple controllers can be established. This communication architecture allows for completely flexible configuration of the master and slave units, and both master and slave controllers possess the same carrier generation and pulse modulation functions, such as... Figure 4 As shown in the diagram, each controller, after outputting a carrier synchronization signal based on the carrier peak and trough indicators, performs an AND operation with the current controller's master-slave flag signal (master = 1, slave = 0) before outputting it to multiple fiber optic output ports for transmission to other controllers. Conversely, each controller performs an OR operation on the multiple carrier synchronization signals received at the fiber optic input port, then performs an AND operation with the inverted master-slave flag signal (master = 1, slave = 0) of the current controller, using this as the final carrier synchronization signal to control carrier generation. The carrier generation method of these controllers is the same as that of the main controller and will not be described further here.

[0067] The multi-converter carrier synchronization control method of the present invention can realize the carrier synchronization of multiple converters, thereby achieving pulse approximate consistency and preventing runaway caused by large zero-sequence current. It can also achieve strict phase misalignment of multiple converter carriers, realize ripple cancellation, and improve output performance.

[0068] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A carrier synchronization control method for multiple converters, wherein each converter has a corresponding controller, characterized in that, The multiple controllers establish pairwise full-duplex fiber optic communication, and each controller can freely select any one of them as the master controller, with the others as slave controllers. When establishing pairwise full-duplex fiber optic communication between multiple controllers, the carrier synchronization control method for each controller includes the following steps: Each controller outputs a carrier peak flag and a carrier trough flag, and then outputs a carrier synchronization signal based on the carrier peak and carrier trough flags. This signal is then ANDed with the master-slave flag signal of the current controller before being output to other controllers. Each controller performs an OR operation on the multiple received carrier synchronization signals, and then performs an AND operation with the inverted master-slave flag signal of the current controller to obtain the final carrier synchronization signal to control carrier generation. In the master-slave flag signal, master is 1 and slave is 0.

2. The carrier synchronization control method for multiple converters according to claim 1, characterized in that, When the carrier wave is in a triangular configuration, the specific process of the main controller outputting the carrier synchronization signal is as follows: Load the initial carrier value and initial carrier direction; where the initial carrier value and initial carrier direction are the carrier value and carrier direction of the first clock cycle after the carrier is enabled. Determine the carrier direction: When the carrier direction increases, the carrier value is incremented by 1. If the actual carrier value reaches its peak value after incrementing by 1, the carrier direction changes to decrease, a carrier peak flag is output, and the process returns to the carrier direction determination stage. If the actual carrier value does not reach its peak value after incrementing by 1, the process directly returns to the carrier direction determination stage and continues to the next determination stage. When the carrier direction decreases, the carrier value is -1. If the actual carrier value after -1 reaches 0, the carrier direction becomes increasing, and a carrier trough flag is output. Then, the process returns to the carrier direction determination stage. If the actual carrier value after -1 does not reach 0, the process directly returns to the carrier direction determination stage and continues to the next determination stage. The master controller outputs a carrier synchronization signal to the slave controller at the carrier peak or carrier trough marker.

3. The carrier synchronization control method for multiple converters according to claim 2, characterized in that, When the carrier is in a triangular configuration, the specific process of generating and applying the input carrier synchronization signal from the corresponding carrier in the controller is as follows: Load the initial carrier value and initial carrier direction; where the initial carrier value and initial carrier direction are the carrier value and carrier direction of the first clock cycle after the carrier is enabled. Determine the carrier direction: When the carrier direction increases, the carrier value is incremented by 1. If the actual carrier value reaches its peak value after incrementing by 1, the carrier direction changes to decrease, a carrier peak flag is output, and the process returns to the carrier direction determination stage. If the actual carrier value does not reach its peak value after incrementing by 1, the process directly returns to the carrier direction determination stage and continues to the next determination stage. When the carrier direction decreases, the carrier value is -1. If the actual carrier value after -1 reaches 0, the carrier direction becomes increasing, and a carrier trough flag is output. Then, the process returns to the carrier direction determination stage. If the actual carrier value after -1 does not reach 0, the process directly returns to the carrier direction determination stage and continues to the next determination stage. When the controller receives the carrier synchronization signal from the main controller in real time, it directly returns to the step of loading the initial carrier value and the initial carrier direction. Finally, a carrier signal synchronized with the main controller is generated.

4. The carrier synchronization control method for a multi-converter according to claim 1 or 2, characterized in that, When the carrier mode is sawtooth wave, the specific process of the main controller outputting the carrier synchronization signal is as follows: The carrier direction is determined. When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is incremented by 1. If the actual carrier value after incrementing by 1 reaches the peak value, the carrier value is directly changed to 0, and the carrier peak and valley flag is output. Then, the process returns to the carrier value increment step. If the actual carrier value after incrementing by 1 does not reach the peak value, the process returns directly to the carrier value increment step and continues to the next step. The initial carrier value is the carrier value in the first frame after the carrier enable is active; When the carrier direction decreases, the initial carrier value is loaded, and then the carrier value is decremented by 1. If the actual carrier value after decrementing by 1 reaches 0, the carrier value directly becomes the peak value, and the carrier peak-valley flag is output. Then, the process returns to the carrier value decrementing step. If the actual carrier value after decrementing by 1 does not reach 0, the process directly returns to the carrier value decrementing step and continues to the next step for judgment. The master controller outputs a carrier synchronization signal to the slave controller at the carrier peak or carrier trough marker.

5. The carrier synchronization control method for multiple converters according to claim 4, characterized in that, When the carrier mode is sawtooth wave, the specific process of generating and applying the input carrier synchronization signal from the controller corresponding to the carrier is as follows: The carrier direction is determined. When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is incremented by 1. If the actual carrier value after incrementing by 1 reaches the peak value, the carrier value is directly changed to 0, and the carrier peak and valley flag is output. Then, the process returns to the carrier value increment step. If the actual carrier value after incrementing by 1 does not reach the peak value, the process returns directly to the carrier value increment step and continues to the next step. The initial carrier value is the carrier value in the first frame after the carrier enable is active; When the carrier direction increases, the initial carrier value is loaded, and then the carrier value is decremented by 1. If the actual carrier value after decrementing by 1 reaches 0, the carrier value directly becomes the peak value, and the carrier peak-valley flag is output. Then, the process returns to the carrier value decrementing step. If the actual carrier value after decrementing by 1 does not reach 0, the process directly returns to the carrier value decrementing step and continues to the next step for judgment. When the controller receives the carrier synchronization signal from the main controller in real time, it directly returns to the step of loading the initial carrier value. Finally, a carrier signal synchronized with the main controller is generated.

6. The carrier synchronization control method for a multi-converter according to claim 1 or 2, characterized in that, When each converter is an AC / DC converter and both the AC and DC sides are directly connected in parallel, the carrier consistency synchronization between the master controller and the slave controller is achieved.

7. The carrier synchronization control method for a multi-converter according to claim 6, characterized in that, The carrier mode is a triangular wave. When the master controller outputs a carrier synchronization signal to the slave controller at the carrier wave trough, and the initial carrier value of each slave controller is set to 0, the carrier consistency synchronization between the master controller and the slave controller is achieved. When the master controller outputs a carrier synchronization signal to the slave controller at the carrier wave peak, and the initial carrier value of each slave controller is set to the carrier wave peak value, the carrier consistency synchronization between the master controller and the slave controller is also achieved.

8. The carrier synchronization control method for a multi-converter according to claim 1 or 2, characterized in that, When each converter is a DC / DC converter and both the input and output sides are directly connected in parallel, the carrier phase misalignment synchronization between the master controller and the slave controller is achieved.

9. The carrier synchronization control method for a multiple converter according to claim 8, characterized in that, The carrier mode is sawtooth wave. When the master controller is at the trough or peak of the carrier wave, it outputs a carrier synchronization signal to the slave controller. The initial carrier value of each slave controller is set to a multiple of 1 / n, 2 / n, ..., (n-1) / n of the carrier peak value, respectively, to achieve strict phase-out synchronization of the carriers among multiple controllers. Here, n is a natural number greater than 1.

10. The carrier synchronization control method for a multiple converter according to claim 1 or 2, characterized in that, Carrier generation and synchronization control are performed on a chip with a high-speed clock on the controller.

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