Control method, control device, grid-connected inverter unit and readable storage medium

Abstract

The present application discloses a control method, a control device, a grid-connected inverter unit and a readable storage medium. The control method includes obtaining a first sampling current at the beginning of a first interruption cycle and a second sampling current at the beginning of a second interruption cycle in a first wave-generating cycle, and the wave-generating cycle is equally divided into a first interruption cycle and a second interruption cycle; calculating a third sampling current at the end of the second interruption cycle according to the first sampling current and the second sampling current; and calculating a duty cycle in the next wave-generating cycle according to the third sampling current. The control method of the grid-connected inverter unit provided in the embodiment of the present application calculates the third sampling current at the beginning of the next wave-generating cycle by using the first sampling current and the second sampling current, and calculates the duty cycle according to the third sampling current, thereby eliminating the delay of the current collection when calculating the duty cycle, which is beneficial for the duty cycle to better meet the current working conditions when extreme working conditions occur, so that the control of the grid-connected inverter unit is relatively smooth.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and more specifically, to a control method, a control device, a grid-connected inverter unit and a readable storage medium. Background Art

[0002] In the control method of the grid-connected inverter unit, it is necessary to collect the bus voltage and AC current into the DSP chip, generate the modulation wave through the dual-loop control operation, and then convert the modulation wave into a duty cycle through the PWM modulation module. In order to avoid conflicts between the modulation wave writing and the duty cycle conversion, it is usually necessary to use a shadow register to delay the time of the modulation wave conversion duty cycle by 1 PWM wave cycle to prevent the modulation wave writing and duty cycle conversion from being carried out at the same time. However, this also leads to a delay in the bus voltage and AC current that generate the duty cycle. When extreme working conditions occur, such as when a capacitive load is put into the inverter side, the sampled current increases rapidly. Due to the delay in the collected bus voltage and AC current, the generated duty cycle cannot meet the current working conditions, which can easily trigger the system's wave-by-wave current limiting function or cause the grid-connected inverter unit to be controlled unevenly. Summary of the invention

[0003] The embodiments of the present application provide a control method, a control device, a grid-connected inverter unit and a readable storage medium to solve at least one of the above-mentioned technical problems.

[0004] The control method of the grid-connected inverter unit according to the embodiment of the present application includes:

[0005] Acquire a first sampling current at the beginning of a first interruption period in a first wave transmission period and a second sampling current at the beginning of a second interruption period, wherein the wave transmission period is equally divided into the first interruption period and the second interruption period;

[0006] Calculate a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current;

[0007] The duty cycle is calculated in the next wave generation cycle according to the third sampling current.

[0008] The control method of the grid-connected inverter unit provided in the embodiment of the present application calculates the third sampling current at the beginning of the next wave transmission cycle through the first sampling current and the second sampling current, and calculates the duty cycle according to the third sampling current, thereby eliminating the delay of collecting the current when calculating the duty cycle. This is beneficial when extreme working conditions occur, so that the duty cycle can better meet the current working conditions, avoid triggering the wave-by-wave current limiting function of the system, and make the control of the grid-connected inverter unit relatively smooth.

[0009] In some embodiments, calculating a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current includes:

[0010] The relationship among the first sampling current, the second sampling current and the third sampling current is:

[0011] I(t1)=2×I(t0_1)-I(t0);

[0012] Wherein, I(t0) is the first sampling current, I(t0_1) is the second sampling current, and I(t1) is the third sampling current.

[0013] In this way, when the carrier wave is a triangular wave, there is symmetry in the current waveform around one PWM wave transmission cycle, and calculating the third sampling current based on this can make the calculated value of the third sampling current more accurate.

[0014] In some embodiments, current sampling points of the first sampling current and the second sampling current are located in a transformer on a DC side or an AC side.

[0015] In this way, the first sampling current and the second sampling current can be accurately measured, which helps to achieve precise control.

[0016] In some embodiments, calculating the duty cycle according to the third sampled current includes:

[0017] Get the sampled voltage of the first wave generation cycle;

[0018] According to the sampled voltage and the third sampled current, a voltage regulation amount and a current regulation amount are obtained by using a dual-loop control algorithm;

[0019] generating a modulation wave according to the voltage adjustment amount and the current adjustment amount;

[0020] The duty cycle is calculated according to the modulation wave in the next wave transmission cycle.

[0021] In this way, the output power of the inverter can be flexibly adjusted, which helps to adapt to different load and grid requirements.

[0022] In some embodiments, obtaining the sampled voltage of the first wave transmission cycle includes:

[0023] The bus voltage value is collected in real time as the sampling voltage through the sampling circuit.

[0024] In this way, by collecting the bus voltage value in real time, the fluctuation of the bus voltage can be discovered and processed in time, so as to adjust the output voltage of the inverter and ensure the stability of the output voltage.

[0025] In some embodiments, the step of obtaining a voltage regulation amount and a current regulation amount by using a dual-loop control algorithm according to the sampled voltage and the third sampled current includes:

[0026] Preprocessing the sampled voltage;

[0027] The required voltage regulation amount is calculated according to the pre-processed sampled voltage through a voltage loop control algorithm.

[0028] In this way, by using the voltage loop control algorithm to calculate the voltage regulation amount, it can be ensured that the output voltage can be maintained near the set value to avoid excessive fluctuations.

[0029] In some embodiments, the step of obtaining a voltage regulation amount and a current regulation amount by using a dual-loop control algorithm according to the sampled voltage and the third sampled current includes:

[0030] Preprocessing the third sampling current;

[0031] The required current regulation amount is calculated according to the preprocessed third sampling current through the current loop control algorithm.

[0032] In this way, by calculating the current regulation amount using the current loop control algorithm, precise control of the output current can be achieved.

[0033] The control device of the grid-connected inverter unit according to the second embodiment of the present application includes:

[0034] An acquisition module, used for acquiring a first sampling current at the beginning of a first interruption period in a first wave transmission period and a second sampling current at the beginning of a second interruption period, wherein the wave transmission period is equally divided into the first interruption period and the second interruption period;

[0035] A first calculation module, configured to calculate a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current;

[0036] The second calculation module is used to calculate the duty cycle in the next wave transmission period according to the third sampling current.

[0037] The grid-connected inverter unit of the third embodiment of the present application includes a processor and a memory, wherein the memory stores a computer program. When the computer program is executed by the processor, the processor implements the control method as described in any one of the above items.

[0038] The fourth embodiment of the present application is a non-volatile computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method as described in any one of the above items is implemented.

[0039] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0041] Figure 1 is a flow chart of a control method of a grid-connected inverter unit according to an embodiment of the present application;

[0042] Figure 2 is a module schematic diagram of a control device for a grid-connected inverter unit according to an embodiment of the present application;

[0043] Figure 3 is a module schematic diagram of a grid-connected inverter unit according to an embodiment of the present application;

[0044] Figure 4 is a current timing diagram of a grid-connected inverter unit according to an embodiment of the present application;

[0045] Figure 5 is a flow chart of a control method of a grid-connected inverter unit in certain embodiments of the present application;

[0046] Figure 6 is a flow chart of a control method of a grid-connected inverter unit in certain embodiments of the present application;

[0047] Figure 7 It is a flow chart of a control method of a grid-connected inverter unit in certain embodiments of the present application.

[0048] Description of the main component symbols: grid-connected inverter unit 100 , control device 10 , acquisition module 11 , first calculation module 12 , second calculation module 13 , processor 20 , memory 30 . DETAILED DESCRIPTION

[0049] The following further describes the embodiments of the present application in conjunction with the accompanying drawings. The same or similar reference numerals in the accompanying drawings represent the same or similar elements or elements with the same or similar functions.

[0050] In addition, the embodiments of the present application described below in conjunction with the drawings are exemplary and are only used to explain the embodiments of the present application and should not be construed as limiting the present application.

[0051] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0052] In the control method of the grid-connected inverter unit, it is necessary to collect the bus voltage and AC current into the DSP chip, generate the modulation wave through the dual-loop control operation, and then convert the modulation wave into a duty cycle through the PWM modulation module. In order to avoid conflicts between the modulation wave writing and the duty cycle conversion, it is usually necessary to use a shadow register to delay the time of the modulation wave conversion duty cycle by 1 PWM wave cycle to prevent the modulation wave writing and duty cycle conversion from being carried out at the same time. However, this also leads to a delay in the bus voltage and AC current that generate the duty cycle. When extreme working conditions occur, such as when a capacitive load is put into the inverter side, the sampled current increases rapidly. Due to the delay in the collected bus voltage and AC current, the generated duty cycle cannot meet the current working conditions, which can easily trigger the system's wave-by-wave current limiting function or cause the grid-connected inverter unit to be controlled unevenly.

[0053] See also Figure 1 , the control method of the grid-connected inverter unit 100 according to the embodiment of the present application includes:

[0054] Step 01: obtaining a first sampling current at the beginning of a first interruption period in a first wave transmission period and a second sampling current at the beginning of a second interruption period, wherein the wave transmission period is equally divided into the first interruption period and the second interruption period;

[0055] Step 02: Calculate a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current;

[0056] Step 03: Calculate the duty cycle in the next wave transmission cycle according to the third sampling current.

[0057] Please refer to Figure 2The control device 10 of the grid-connected inverter unit 100 of the second embodiment of the present application includes an acquisition module 11, a first calculation module 12 and a second calculation module 13, wherein the acquisition module 11 is used to obtain a first sampling current at the beginning of a first interruption cycle and a second sampling current at the beginning of a second interruption cycle in a first wave transmission cycle, and the wave transmission cycle is equally divided into a first interruption cycle and a second interruption cycle. The first calculation module 12 is used to calculate a third sampling current at the end of the second interruption cycle according to the first sampling current and the second sampling current, and the second calculation module 13 is used to calculate the duty cycle in the next wave transmission cycle according to the third sampling current.

[0058] Please refer to Figure 3 The grid-connected inverter unit 100 of the third embodiment of the present application includes a processor 20 and a memory 30. The memory 30 stores a computer program. When the computer program is executed by the processor 20, the processor 20 implements any of the control methods described above. In other words, the processor 20 can be used to obtain a first sampling current at the beginning of a first interruption cycle and a second sampling current at the beginning of a second interruption cycle in a first wave-generating cycle, and the wave-generating cycle is equally divided into a first interruption cycle and a second interruption cycle; calculate a third sampling current at the end of the second interruption cycle based on the first sampling current and the second sampling current; and calculate a duty cycle in the next wave-generating cycle based on the third sampling current.

[0059] The control method of the grid-connected inverter unit 100 provided in the embodiment of the present application calculates the third sampling current at the beginning of the next wave transmission cycle through the first sampling current and the second sampling current, and calculates the duty cycle according to the third sampling current, thereby eliminating the delay of collecting the current when calculating the duty cycle. This is beneficial when extreme working conditions occur, so that the duty cycle can better meet the current working conditions, avoid triggering the wave-by-wave current limiting function of the system, and make the control of the grid-connected inverter unit 100 relatively smooth.

[0060] Specifically, the wave period is the period of the wave, which refers to the time required for a wave to complete a complete vibration cycle. Figure 4 , Figure 4 : is a current timing diagram of an embodiment of the present application. In the embodiment of the present application, the time when the first wave-generating cycle starts is t0, the time when the first wave-generating cycle ends, that is, the time when the next wave-generating cycle starts is t1, and the time when the second wave-generating cycle ends is t2. Both the time periods t0-t1 and t1-t2 are one wave-generating cycle, denoted as T pwm .

[0061] The interrupt cycle is a specific stage in the computer instruction cycle, which occurs in the process of the CPU executing instructions and after the execution cycle. When the CPU is executing instructions, if an interrupt request (such as an interrupt signal from an external device or an internal exception) is detected, it will enter the interrupt cycle. The main function of the interrupt cycle is to allow the CPU to respond to and process other emergency events or external requests while processing the current instruction. Through the interrupt mechanism, the CPU can process input / output requests from external devices, handle abnormal events, or perform other task scheduling while executing a program. In the embodiment of the present application, a wave transmission cycle is evenly divided into two segments to form two interrupt cycles, denoted as T int , please refer to Figure 4 The time when the first interruption cycle ends, that is, the time when the second interruption cycle begins, is t0_1, t0_1 is the midpoint between t0 and t1, t0-t0_1 and t0_1-t1 are two interruption cycles in the first wave transmission cycle, t0-t0_1 is the first interruption cycle in the first wave transmission cycle, and t0_1-t1 is the first interruption cycle in the first wave transmission cycle.

[0062] In the embodiment of the present application, since there are similarities between the left and right current waveforms within one wave transmission cycle when the carrier is a triangular wave, the third sampling current can be predicted and calculated by the first sampling current and the second sampling current, and the third sampling current is the current at the start of the next wave transmission cycle. The duty cycle can be calculated using the third sampling current to offset the delay of one PWM wave transmission cycle caused by using the shadow register.

[0063] In some embodiments, calculating a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current includes:

[0064] The relationship among the first sampling current, the second sampling current and the third sampling current is:

[0065] I(t1)=2×I(t0_1)-I(t0);

[0066] Wherein, I(t0) is the first sampling current, I(t0_1) is the second sampling current, and I(t1) is the third sampling current.

[0067] In this way, when the carrier wave is a triangular wave, there is symmetry in the current waveform around one PWM wave transmission cycle, and calculating the third sampling current based on this can make the calculated value of the third sampling current more accurate.

[0068] For details, please refer to Figure 4 In the embodiment of the present application, the wave period is T pwm, since the left and right current waveforms within one wave transmission cycle are usually centrally symmetrical when the carrier is a triangular wave, that is, the currents at the start, midpoint and end of one cycle should be on the same straight line in the current timing diagram, so it can be concluded that the relationship between the first sampling current, the second sampling current and the third sampling current is: I(t1)=2×I(t0_1)-I(t0).

[0069] In some embodiments, current sampling points of the first sampling current and the second sampling current are located in a transformer on a DC side or an AC side.

[0070] In this way, the first sampling current and the second sampling current can be accurately measured, which helps to achieve precise control.

[0071] Specifically, when selecting the sampling points, multiple factors need to be considered comprehensively, including measurement accuracy, cost, fault tolerance, etc. Sampling inside the transformer can accurately measure the current value inside the transformer with high accuracy and small measurement error, but the selection and implementation of the sampling points may be more complicated. Selecting transformer sampling on the DC side can accurately measure the array power generation current, which helps to achieve precise control and protection. Selecting transformer sampling on the AC side can measure the inverter output current and perform control and protection based on the measurement results. The specific current sampling points of the first sampling current and the second sampling current can be selected according to actual needs, and I will not go into details here.

[0072] See also Figure 5 In some embodiments, step 03 includes:

[0073] 031: Get the sampling voltage of the first wave cycle;

[0074] 032: Obtain a voltage regulation amount and a current regulation amount using a dual-loop control algorithm according to the sampled voltage and the third sampled current;

[0075] 033: Generate a modulation wave according to the voltage adjustment amount and the current adjustment amount;

[0076] 034: Calculate the duty cycle in the next transmission cycle based on the modulation wave.

[0077] In this way, the output power of the inverter can be flexibly adjusted, which helps to adapt to different load and grid requirements.

[0078] In some embodiments, sub-steps 031, 032, 033 and 034 are implemented by the second calculation module 13, or the second calculation module 13 can be used to obtain the sampled voltage of the first wave transmission cycle; obtain the voltage regulation amount and the current regulation amount using the dual-loop control algorithm based on the sampled voltage and the third sampled current; generate a modulation wave based on the voltage regulation amount and the current regulation amount; and calculate the duty cycle in the next wave transmission cycle based on the modulation wave.

[0079] In some embodiments, the processor 20 can be used to obtain a sampled voltage of the first wave transmission cycle; obtain a voltage regulation amount and a current regulation amount using a dual-loop control algorithm based on the sampled voltage and the third sampled current; generate a modulation wave based on the voltage regulation amount and the current regulation amount; and calculate a duty cycle in the next wave transmission cycle based on the modulation wave.

[0080] Specifically, in the embodiment of the present application, the sampled voltage is acquired in the first wave transmission period and the dual-loop control algorithm is used to acquire the voltage regulation amount. The third sampled current is also acquired in the first wave transmission period and the dual-loop control algorithm is used to acquire the voltage regulation amount and the current regulation amount. It should be noted that the sampled voltage acquisition and the third current acquisition are performed simultaneously without any order of precedence. Similarly, the dual-loop control algorithm acquires the voltage regulation amount and the current regulation amount simultaneously without any order of precedence.

[0081] Further, based on the voltage regulation amount and the current regulation amount, a corresponding modulation wave is generated by the digital signal processor 20. The shape and frequency of the modulation wave determine the quality and characteristics of the AC power output by the inverter. Then, in the next wave generation cycle, the modulation wave is sent to the PWM modulation module for further processing to calculate the duty cycle. Figure 4 As shown, Duty(T0) is a duty cycle obtained according to the sampled voltage in the first wave transmission cycle and the third sampled current.

[0082] In some embodiments, obtaining a sampled voltage of a first wave generation cycle includes:

[0083] The bus voltage value is collected in real time as the sampling voltage through the sampling circuit.

[0084] In this way, by collecting the bus voltage value in real time, the fluctuation of the bus voltage can be discovered and processed in time, so as to adjust the output voltage of the inverter and ensure the stability of the output voltage.

[0085] Specifically, in the embodiment of the present application, the sampling circuit can capture the value of the bus voltage in real time and convert it into a digital signal for subsequent processing. This enables the system to monitor the changes in the bus voltage in real time, thereby promptly discovering voltage fluctuations or abnormal conditions. Optionally, the sampling method of the sampling circuit can select a resistor voltage division method, a linear photoelectric coupler isolation sampling method, etc.

[0086] The bus is the transmission channel of DC power in the inverter, and the output voltage of the inverter is also realized through the bus. By collecting the bus voltage value in real time, the fluctuation of the bus voltage can be discovered and processed in time, so as to adjust the output voltage of the inverter and ensure the stability of the output voltage.

[0087] Real-time acquisition of bus voltage values ​​can also help the inverter achieve more efficient operation. By processing and analyzing the sampled data, problems such as inverter output voltage fluctuations and grid voltage fluctuations can be discovered in a timely manner, and the inverter can be adjusted in a timely manner to optimize its working state and improve operating efficiency.

[0088] In addition, real-time acquisition of bus voltage values ​​and control of the inverter accordingly can enhance the robustness of the system. When the grid voltage fluctuates or the inverter encounters other abnormal conditions, the system can respond quickly and take appropriate protective measures to prevent the inverter from being damaged or affecting normal operation. This helps to improve the reliability and stability of the system and ensure the long-term stable operation of the photovoltaic power generation system.

[0089] See also Figure 6 In some embodiments, sub-step 032 includes:

[0090] 0321: pre-process the sampled voltage;

[0091] 0322: The required voltage regulation amount is calculated based on the pre-processed sampled voltage through the voltage loop control algorithm.

[0092] In this way, by using the voltage loop control algorithm to calculate the voltage regulation amount, it can be ensured that the output voltage can be maintained near the set value to avoid excessive fluctuations.

[0093] In some embodiments, sub-steps 0321 and 0322 are implemented by the second calculation module 13, or the second calculation module 13 can be used to pre-process the sampled voltage; and calculate the required voltage regulation amount through the voltage loop control algorithm based on the pre-processed sampled voltage.

[0094] In some embodiments, the processor 20 may be used to pre-process the sampled voltage; and calculate the required voltage regulation amount through a voltage loop control algorithm according to the pre-processed sampled voltage.

[0095] Specifically, the voltage preprocessing before the voltage loop control generates the modulation wave mainly includes voltage signal filtering, denoising, etc., which is used to eliminate harmonic interference, high-frequency noise interference, power frequency interference, electromagnetic radiation interference, drift interference caused by temperature changes, etc., thereby ensuring the accuracy and stability of the voltage signal and improving the performance and reliability of the grid-connected inverter unit 100.

[0096] In an embodiment of the present application, the voltage loop control algorithm calculates the required voltage regulation amount. First, the reference voltage should be determined. The reference voltage is usually set by the system or determined according to the control target. Then the pre-processed collected voltage is compared with the reference voltage to calculate the voltage error. Then the voltage loop controller is used to adjust and calculate the voltage regulation amount according to the voltage error. The output of the PI controller is a control signal, which is used to adjust the switching state of the inverter or the duty cycle of the modulation wave, thereby changing the output voltage. Among them, the voltage loop controller usually adopts a PI (proportional-integral) controller.

[0097] See also Figure 7 In some embodiments, sub-step 032 includes:

[0098] 0323: pre-processing the third sampling current;

[0099] 0324: Calculate the required current regulation amount through the current loop control algorithm according to the third sampling current after preprocessing.

[0100] In this way, by calculating the current regulation amount using the current loop control algorithm, precise control of the output current can be achieved.

[0101] In some embodiments, sub-steps 0323 and 0324 are implemented by the second calculation module 13, or the second calculation module 13 can be used to preprocess the third sampled current; and calculate the required current regulation amount through the current loop control algorithm according to the preprocessed third sampled current.

[0102] In some embodiments, the processor 20 may be used to pre-process the third sampled current; and calculate the required current regulation amount through a current loop control algorithm according to the pre-processed third sampled current.

[0103] Specifically, the current preprocessing step before the current loop control generates the modulation wave also includes filtering and denoising of the current signal, etc., to eliminate environmental interference, power supply noise, sensor noise, signal processing noise, numerical calculation errors, etc., to ensure the accuracy and stability of the current signal.

[0104] In an embodiment of the present application, similar to the voltage loop control algorithm, the current loop control algorithm calculates the required current regulation amount. First, the reference current should be determined. The reference current is the desired current value, which is usually determined by the output of the speed loop or the position loop, or is directly set according to the control target of the system. Then the third sampled current is compared with the reference current to calculate the current error. Then adjust according to the current error. The output of the controller is a control signal, which is used to adjust the switching state of the inverter or the duty cycle of the modulation wave, thereby changing the output current. The current loop controller usually adopts a PI (proportional-integral) controller or a P (proportional) controller. It should be noted that when selecting a current loop controller, it is necessary to select a suitable controller type according to the specific requirements and characteristics of the system.

[0105] The non-volatile computer-readable storage medium of the fourth embodiment of the present application stores a computer program. When the computer program is executed by the processor 20, any of the control methods described above is implemented.

[0106] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital video disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0107] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0108] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, unless otherwise clearly and specifically defined.

[0109] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A control method for a grid-connected inverter unit, characterized in that: include: Acquire a first sampling current at the beginning of a first interruption period in a first wave transmission period and a second sampling current at the beginning of a second interruption period, wherein the wave transmission period is equally divided into the first interruption period and the second interruption period; Calculate a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current; The duty cycle is calculated in the next wave generation cycle according to the third sampling current.

2. The control method according to claim 1, characterized in that: The calculating the third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current includes: The relationship among the first sampling current, the second sampling current and the third sampling current is: I(t1)=2×I(t0_1)-I(t0); Wherein, I(t0) is the first sampling current, I(t0_1) is the second sampling current, and I(t1) is the third sampling current.

3. The control method according to claim 1, characterized in that: Current sampling points of the first sampling current and the second sampling current are located in a transformer on a DC side or an AC side.

4. The control method according to claim 1, characterized in that: The calculating the duty cycle according to the third sampling current comprises: Get the sampled voltage of the first wave generation cycle; According to the sampled voltage and the third sampled current, a voltage regulation amount and a current regulation amount are obtained by using a dual-loop control algorithm; generating a modulation wave according to the voltage adjustment amount and the current adjustment amount; The duty cycle is calculated according to the modulation wave in the next wave transmission cycle.

5. The control method according to claim 4, characterized in that: The step of obtaining the sampled voltage of the first wave generation cycle includes: The bus voltage value is collected in real time as the sampling voltage through the sampling circuit.

6. The control method according to claim 4, characterized in that: The step of obtaining a voltage regulation amount and a current regulation amount by using a dual-loop control algorithm according to the sampled voltage and the third sampled current includes: Preprocessing the sampled voltage; The required voltage regulation amount is calculated according to the pre-processed sampled voltage through a voltage loop control algorithm.

7. The control method according to claim 4, characterized in that: The step of obtaining a voltage regulation amount and a current regulation amount by using a dual-loop control algorithm according to the sampled voltage and the third sampled current includes: Preprocessing the third sampling current; The required current regulation amount is calculated according to the preprocessed third sampling current through the current loop control algorithm.

8. A control device for a grid-connected inverter unit, characterized in that: include: An acquisition module, used for acquiring a first sampling current at the beginning of a first interruption period in a first wave transmission period and a second sampling current at the beginning of a second interruption period, wherein the wave transmission period is equally divided into the first interruption period and the second interruption period; A first calculation module, configured to calculate a third sampling current at the end of the second interruption period according to the first sampling current and the second sampling current; The second calculation module is used to calculate the duty cycle in the next wave transmission period according to the third sampling current.

9. A grid-connected inverter unit, characterized in that: The method comprises a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor implements the control method according to any one of claims 1 to 7.

10. A non-volatile computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the control method according to any one of claims 1 to 7 is implemented.

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