A control method of an inverter and an inverter

Abstract

This application proposes a control method for an inverter, including: S10: obtaining the current AC voltage sample value V when the inverter is in grid-connected operation. ac_AD2 S20: Determine V ac_AD2 Does it cross zero positively? If yes, proceed to step S30; otherwise, proceed to step S40. S30: Reset N to 0 (N is a natural number) and proceed to step S10. S40: Update the stored value V. N‑2 =V N‑1 V N‑1 =V N V N =V ac_AD2 S50: Calculate and obtain the current compensation value NewDeltaV N‑2 =V N ‑ V N‑2 S60: Obtain the data from memory related to V ac_AD2 The corresponding pre-stored compensation value PreDeltaV N‑2 S70: According to New Delta V N‑2 and PreDeltaV N‑2 Obtain updated compensation value DeltaV N‑2 And update the pre-stored compensation value PreDeltaV in memory. N‑2 =DeltaV N‑2 S80: Obtain from memory and V ac_AD2 The corresponding PreDeltaV N And according to V ac_AD2 and PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL S90: Output V AC_CONTROL Then update N=N+1 and proceed to step S10.

Description

Technical Field

[0001] This application relates to the field of power supply, and in particular to a control method for an inverter and an inverter. Background Technology

[0002] Inverters are used to convert direct current (DC) to alternating current (AC), and have been widely used in recent years in areas such as grid connection of new energy sources.

[0003] In inverter grid-connected control systems employing digital signal processors (DSPs) or microcontrollers (MCUs), the sampling of grid voltage and current and the output of switching control signals for the inverter's main circuit are typically performed with fixed interrupt cycles, introducing an inherent system latency problem. Specifically, there is a delay of approximately one interrupt cycle (Ts) from the time the grid voltage signal is sampled by the ADC (analog-to-digital converter) to the time the interrupt service routine is entered for calculation. Furthermore, there is another delay of approximately one interrupt cycle from the completion of the interrupt routine calculation to the output of the corresponding modulated wave by the PWM (pulse width modulation) driver. Therefore, the total delay from voltage sampling to the output of the switching control signal for the inverter's main circuit is approximately two interrupt cycles (2Ts).

[0004] This delay causes the controller to use historical grid voltage information from two cycles ago, rather than the current actual value. For grid-connected inverters that need to quickly and accurately track the phase and amplitude of the grid voltage, this delay introduces phase deviation and amplitude error, leading to a decrease in grid current quality (such as increased total harmonic distortion (THD)).

[0005] This problem is particularly severe under weak grid conditions. A weak grid typically refers to a power supply network with high grid impedance, where the grid voltage is inherently prone to fluctuations and distortions due to load changes and power injection from distributed generation sources. In this scenario:

[0006] 1. Phase errors caused by sampling delay will cause the inverter's control response to lag, which may exacerbate grid voltage fluctuations.

[0007] 2. Delay will change the phase characteristics of the control loop, and at certain frequencies may form positive feedback with the grid impedance and inverter output filter, inducing or aggravating system resonance and threatening the stable operation of the system.

[0008] Existing technologies for addressing delay and resonance issues typically employ complex algorithms such as state observers, repetitive predictive control, or model-based phase lead compensation. For example, resonance is suppressed by establishing discrete predictive models or predicting capacitor voltage. However, these methods suffer from the following significant drawbacks:

[0009] 1. Computational complexity: It relies on an accurate mathematical model of the system, the algorithm has a large amount of computation, and it requires high computing power from the controller, which increases hardware costs.

[0010] 2. Parameter sensitivity: The compensation effect is highly dependent on the accuracy of system parameters (such as LCL filter parameters). In practical applications, due to factors such as component aging and temperature drift, the parameters will change, leading to a decrease in the compensation effect or even introducing unstable factors.

[0011] 3. Difficulty in implementation: The complex control algorithm increases the difficulty of software development and debugging, and the engineering implementation threshold is high. Summary of the Invention

[0012] According to one embodiment, this application provides a control method for an inverter, including: S10: obtaining the current AC voltage sampling value V when the inverter is in grid-connected operation. ac_AD2 S20: Determine the current AC voltage sampling value V ac_AD2 Does it cross zero positively? If yes, proceed to step S30; otherwise, proceed to step S40. S30: Reset N to 0, where N is a natural number, and proceed to step S10. S40: Update the stored value V. N-2 =V N-1 V N-1 =V N V N =V ac_AD2 S50: Calculate and obtain the current compensation value NewDeltaV N-2 =V N - V N-2 S60: Obtain the sampled value V of the current AC voltage from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N-2 S70: Based on the current compensation value NewDeltaV N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 S80: Obtain the sampled value V of the current AC voltage from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N And based on the current AC voltage sample value V ac_AD2 and the pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL S90: Output the current actual AC voltage feedback value V AC_CONTROL Then update N=N+1 and proceed to step S10.

[0013] Furthermore, it also includes: S110: Obtaining the current AC voltage sampling value V before the inverter is connected to the grid. ac_AD1 S120: Determine the current AC voltage sampling value V ac_AD1 Is it a positive zero crossing? If yes, proceed to step S130; otherwise, proceed to step S150. S130: Determine the current AC voltage sampling value V. ac_AD1 Is this the first positive zero crossing? If yes, proceed to step S140; otherwise, proceed to step S180. S140: Reset N to 0, where N is a natural number. S150: Update the stored value V. N-2 =V N-1 V N-1 =V N V N =V ac_AD1 S160: Calculate and obtain the pre-stored compensation value PreDeltaV N-2 And store; S170: Update N=N+1, proceed to step S110; S180: End.

[0014] Furthermore, after step S90, the following step is also included: S100: The controller receives the current actual AC voltage feedback value V. AC_CONTROL And based on the current actual AC voltage feedback value V AC_CONTROL Output control signals for the switching of the inverter's main circuit.

[0015] Furthermore, step S60 includes: S61: obtaining the current AC voltage sample value V ac_AD2 The corresponding phase value; S62: Query the memory to obtain the pre-stored compensation value PreDeltaV corresponding to the phase value shifted forward by two phase intervals. N-2 .

[0016] Furthermore, step S70 involves: using a filtering unit to filter the current compensation value NewDeltaV... N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 .

[0017] Furthermore, the filtering unit performs DeltaV N-2 = PreDeltaV N-2 * a + NewDeltaV N-2 *(1-a), where a is between 0 and 1.

[0018] Furthermore, step S80 is: according to formula VAC_CONTROL = V ac_AD2 - PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL .

[0019] This application also provides an inverter, comprising: an inverter main circuit, including at least one switching transistor, for converting DC power received at its DC terminal into AC power output at its AC terminal; a voltage sampling circuit, connected to the AC terminal of the inverter main circuit, for obtaining AC voltage sampling values; a memory, which stores a pre-stored compensation value array for one power frequency cycle; and a processing unit, for updating the pre-stored compensation value array in the memory and processing the current AC voltage sampling value V obtained by the inverter operating in grid-connected mode. ac_AD2 and the current AC voltage sample value V in the memory ac_AD2 The corresponding pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL The controller receives the current actual AC voltage feedback value V. AC_CONTROL The output controls the switching signals of the switching transistors in the main circuit of the inverter.

[0020] Furthermore, the processing unit executes: S10: Obtain the current AC voltage sampling value V in the inverter's grid-connected operation state. ac_AD2 S20: Determine the current AC voltage sampling value V ac_AD2 Does it cross zero positively? If yes, proceed to step S30; otherwise, proceed to step S40. S30: Reset N to 0, where N is a natural number, and proceed to step S10. S40: Update the stored value V. N-2 =V N-1 V N-1 =V N V N =V ac_AD2 S50: Calculate and obtain the current compensation value NewDeltaV N-2 =V N - V N-2 S60: Obtain the sampled value V of the current AC voltage from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N-2 S70: Based on the current compensation value NewDeltaV N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2S80: Obtain the sampled value V of the current AC voltage from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N And based on the current AC voltage sample value V ac_AD2 and the pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL S90: Output the current actual AC voltage feedback value V AC_CONTROL Then update N=N+1 and proceed to step S10.

[0021] Furthermore, the processing unit also performs: S110: Obtaining the current AC voltage sampling value V before the inverter is connected to the grid. ac_AD1 S120: Determine the current AC voltage sampling value V ac_AD1 Is it a positive zero crossing? If yes, proceed to step S130; otherwise, proceed to step S150. S130: Determine the current AC voltage sampling value V. ac_AD1 Is this the first positive zero crossing? If yes, proceed to step S140; otherwise, proceed to step S180. S140: Reset N to 0, where N is a natural number. S150: Update the stored value V. N-2 =V N-1 V N-1 =V N V N =V ac_AD1 S160: Calculate and obtain the pre-stored compensation value PreDeltaV N-2 And store; S170: Update N=N+1, proceed to step S110; S180: End.

[0022] The features and technical advantages of this disclosure have been outlined quite extensively above to facilitate a better understanding of the detailed description that follows. Additional features and advantages of this disclosure, which form the subject matter of the claims, will be described below. Those skilled in the art will understand that the disclosed concepts and specific embodiments can be readily used as the basis for modifying or designing other structures or processes for achieving the same purpose as this disclosure. Those skilled in the art will also recognize that such equivalent structures do not depart from the spirit and scope of this disclosure as set forth in the appended claims. Attached Figure Description

[0023] To gain a more complete understanding of this disclosure and its advantages, the following description is given in conjunction with the accompanying drawings, wherein:

[0024] Figure 1 A schematic flowchart of an inverter control method according to an embodiment of this application is shown;

[0025] Figure 2This diagram illustrates the AC voltage and current waveforms in the prior art when there are significant harmonics in the mains voltage.

[0026] Figure 3 The diagram shows the AC voltage and current waveforms under conditions where there are relatively large harmonics in the grid voltage after adopting the control method of the inverter provided in this application;

[0027] Figure 4 This invention illustrates a schematic diagram of a process for obtaining a pre-stored compensation value before the inverter is connected to the grid, according to an embodiment of this application.

[0028] Figure 5 A schematic block diagram of an inverter circuit according to an embodiment of this application is shown.

[0029] Unless otherwise stated, corresponding numbers and symbols in the various figures generally refer to corresponding parts. These figures are drawn to clearly illustrate relevant aspects of the various embodiments and are not necessarily drawn to scale. Detailed Implementation

[0030] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] One embodiment of this application provides a control method for an inverter; please refer to [link / reference]. Figure 1 The schematic diagram shown is a flowchart of an inverter control method according to an embodiment of this application. The inverter control method proposed in this application includes:

[0032] S10: Obtain the current AC voltage sampling value V when the inverter is in grid-connected operation. ac_AD2 ;

[0033] S20: Determine the current AC voltage sampling value V ac_AD2 Is it a positive zero crossing? If yes, proceed to step S30; otherwise, proceed to step S40.

[0034] S30: Reset N to 0, where N is a natural number, and proceed to step S10;

[0035] S40: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD2 ;

[0036] S50: Calculate and obtain the current compensation value NewDeltaVN-2 =V N - V N-2 ;

[0037] S60: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N-2 ;

[0038] S70: Based on the current compensation value NewDeltaV N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 ;

[0039] S80: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N And based on the current AC voltage sample value V ac_AD2 and the pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL ;

[0040] S90: Output the current actual AC voltage feedback value V AC_CONTROL Then update N=N+1 and proceed to step S10.

[0041] As can be seen, after the inverter is connected to the grid, this application continuously and smoothly updates the compensation value through the aforementioned dynamic tracking mechanism. This two-stage strategy of "initial calibration + dynamic update" allows the compensation value to adapt to minor changes in system delay caused by chip temperature rise, component aging, etc., thereby achieving a more accurate and robust compensation effect. Specifically, the pre-stored compensation value PreDeltaV N This is one of the pre-stored compensation value arrays stored in memory, where N is a natural number. In practical applications, before the inverter is connected to the grid, the inherent transmission delay of the system can be obtained through a one-time measurement to form a pre-stored compensation value array, which is then stored in memory. During the first power frequency cycle of the inverter's grid-connected operation, this pre-stored compensation value array can be used to update the pre-stored compensation value array used during grid-connected operation and obtain the current actual AC voltage feedback value V. AC_CONTROL During the second and subsequent power frequency cycles of inverter grid-connected operation, the pre-stored compensation value array can be updated using the pre-stored compensation value array from the previous cycle stored in memory to obtain the current actual AC voltage feedback value V. AC_CONTROLThis means implementing a two-stage strategy of "initial calibration + dynamic update".

[0042] More specifically, after grid connection, the compensation value of the AC voltage sampling value adopts a dynamic update mechanism. That is, it is no longer a fixed value, but a variable that can adaptively adjust according to the actual operating state of the system (such as slight changes in delay characteristics caused by chip temperature and component aging). This ensures that the compensation effect remains optimal throughout the entire life cycle of the inverter, with an accuracy far exceeding that of a one-time calibration scheme.

[0043] As can be seen from the above description, although this application adds a dynamic update step, the core algorithm is still only a simple four arithmetic operations, the amount of computation is still very small, and it is easy to implement on low-performance MCUs. That is, it has the advantages of simple calculation, high real-time performance and low cost.

[0044] Furthermore, it is evident that this application directly measures delay error through system self-calibration and self-updating, completely avoiding the dependence on complex mathematical models inherent in traditional methods. This results in extremely strong robustness and ease of engineering implementation. Thus, this application achieves a low-cost, high-reliability approach to effectively suppress the negative impact of sampling delay on grid-connected performance, particularly reducing voltage fluctuations and suppressing system resonance under weak grid conditions.

[0045] In practical implementation, the inverter control method further includes the following step after step S90: S100: The controller receives the current actual AC voltage feedback value V. AC_CONTROL And based on the current actual AC voltage feedback value V AC_CONTROL The output controls the switching control signal of the inverter's main circuit. As can be seen, the inverter control method provided in this application allows the controller to obtain the switching control signal for the inverter's main circuit based on real-time and accurate AC voltage feedback values. This helps reduce voltage fluctuations under weak grid conditions and suppresses system resonance by improving the phase characteristics of the control loop. See also... Figure 2 The diagram shows AC voltage and current waveforms of the prior art under conditions of significant harmonics in the mains voltage. It is evident that the prior art is prone to large current spikes under such conditions, and distortion can lead to incorrect calculations, causing the system to malfunction and fail to operate normally at time t0 due to protection mechanisms. However, further reference... Figure 3 The diagram shown illustrates the AC voltage and current waveforms under conditions of significant grid harmonics after employing the inverter control method provided in this application. It is evident that even with substantial grid harmonics, the AC output current remains relatively smooth, and the system continues to operate normally. This demonstrates that the inverter control method proposed in this application improves system reliability and effectively enhances the performance of weak grid applications.

[0046] More specifically, in one embodiment of this application, please refer to Figure 4The flowchart shown is a schematic diagram of the process of obtaining a pre-stored compensation value before the inverter is connected to the grid, according to an embodiment of this application. That is, the inverter control method proposed in this application also includes:

[0047] S110: Obtain the current AC voltage sampling value V before the inverter is connected to the grid. ac_AD1 ;

[0048] S120: Determine the current AC voltage sampling value V ac_AD1 Is it a positive zero crossing? If yes, proceed to step S130; otherwise, proceed to step S150.

[0049] S130: Determine the current AC voltage sampling value V ac_AD1 Is this the first positive zero crossing? If yes, proceed to step S140; otherwise, proceed to step S180.

[0050] S140: Reset N to 0, where N is a natural number;

[0051] S150: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD1 ;

[0052] S160: Calculate and obtain the pre-stored compensation value PreDeltaV N-2 And store;

[0053] S170: Update N=N+1, proceed to step S110;

[0054] S180: End.

[0055] As can be seen, before the inverter is connected to the grid, this application controls the inverter to operate and repeatedly executes steps S110 to S180 to obtain the deviation between the sampled value and the actual value (i.e., the value after a delay of two control cycles) at each sampling point within one power frequency cycle, thus forming a pre-stored compensation value array within one power frequency cycle. Each value in the pre-stored compensation value array corresponds to a phase value within one power frequency cycle from 0° to 360°. Taking a power grid frequency of 50Hz and a controller frequency of 20kHz as an example, it can be seen that a pre-stored compensation value array consisting of 400 pre-stored compensation values ​​can be obtained within one power frequency cycle, and the correspondence table between the pre-stored compensation value array and the phase can be stored in memory.

[0056] Furthermore, as can be seen from step S150, during the process of obtaining the pre-stored compensation value array, the memory only needs to store the sampled values ​​of the current time, the previous time, and the two previous times, thus occupying a small amount of memory space.

[0057] In a specific implementation, in one embodiment of this application, step S60 includes: S61: obtaining the current AC voltage sampling value V. ac_AD2 The corresponding phase value; S62: Query the memory to obtain the pre-stored compensation value PreDeltaV corresponding to the phase value shifted forward by two phase intervals. N-2 In practical applications, the phase interval is determined by the power frequency and the control frequency, and its phase interval is 360° / (fc / fs), where fc is the controller's control frequency and fs is the power frequency. For example, taking a power frequency fs of 50Hz and a controller control frequency fc of 20kHz as an example, it can be seen that within one power frequency cycle, a pre-stored compensation value array consisting of 400 (fc / fs) pre-stored compensation values ​​can be obtained, and the phase interval is 360° / 400 = 0.9°. Therefore, if the current AC voltage sample value V obtained in step S61... ac_AD2 The corresponding phase value is 45°; then step S62: retrieve the pre-stored compensation value PreDeltaV corresponding to the phase value shifted forward by two phase intervals from the memory. N-2 This is the pre-stored compensation value corresponding to a phase value of 43.2°. In actual implementation, the current AC voltage sampling value V can be obtained through a phase-locked loop. ac_AD2 The corresponding phase value is then used to look up the pre-stored compensation value array and the corresponding phase in the memory to obtain the pre-stored compensation value PreDeltaV corresponding to the current AC voltage sampling value. N-2 .

[0058] In a specific implementation, in one embodiment of this application, step S70 is: using a filtering unit to filter the current compensation value NewDeltaV... N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 This means implementing a two-stage strategy of "initial calibration + dynamic update".

[0059] In one specific embodiment, a combination of "initial calibration + dynamic update" is achieved by employing a first-order low-pass filter. Specifically, the filtering unit performs DeltaV... N-2 = PreDeltaV N-2 * a + NewDeltaV N-2 * (1-a), where a is between 0 and 1. Using a first-order low-pass filter for updating effectively smooths out the interference of occasional noise and glitches in the grid voltage on the compensation value calculation, preventing drastic jumps in the compensation value due to single sampling anomalies, and ensuring the stability of system control.

[0060] However, this application is not limited to a first-order low-pass filter; any suitable filter can be used, such as a band-pass filter, which can actually be implemented using a digital controller.

[0061] In one specific embodiment, step S80 is: according to formula V AC_CONTROL = V ac_AD2 - PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL Similarly, the current AC voltage sample value V is obtained through a phase-locked loop. ac_AD2 The corresponding phase value is used to obtain the pre-stored compensation value DeltaV at that phase value. N Therefore, according to the formula V AC_CONTROL = V ac_AD2 - DeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL .

[0062] One embodiment of this application also provides an inverter, which can be referred to in [reference]. Figure 5 The schematic diagram of an inverter circuit according to an embodiment of this application shown includes:

[0063] The inverter main circuit 10 includes at least one switching transistor for converting the DC power VDCin received at its DC terminal into the AC power VACout output at its AC terminal.

[0064] Voltage sampling circuit 21 is connected to the AC terminal of the inverter main circuit 10 and is used to obtain AC voltage sampling value;

[0065] Memory 23 stores an array of pre-stored compensation values ​​for one power frequency cycle;

[0066] Processing unit 22 updates the pre-stored compensation value array in the memory, and calculates the current AC voltage sampling value V obtained by the inverter operating in grid-connected mode. ac_AD2 and the current AC voltage sample value V in the memory ac_AD2 The corresponding pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL ;

[0067] Controller 24 receives the current actual AC voltage feedback value V AC_CONTROL The output controls the switching signals of the switching transistors in the main circuit of the inverter.

[0068] Furthermore, the processing unit 22 performs:

[0069] S10: Obtain the current AC voltage sampling value V when the inverter is in grid-connected operation. ac_AD2 ;

[0070] S20: Determine the current AC voltage sampling value V ac_AD2 Is it a positive zero crossing? If yes, proceed to step S30; otherwise, proceed to step S40.

[0071] S30: Reset N to 0, where N is a natural number, and proceed to step S10;

[0072] S40: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD2 ;

[0073] S50: Calculate and obtain the current compensation value NewDeltaV N-2 =V N - V N-2 ;

[0074] S60: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N-2 ;

[0075] S70: Based on the current compensation value NewDeltaV N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 ;

[0076] S80: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N And based on the current AC voltage sample value V ac_AD2 and the pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL ;

[0077] S90: Output the current actual AC voltage feedback value V AC_CONTROL Then update N=N+1 and proceed to step S10.

[0078] Furthermore, the processing unit 22 also performs:

[0079] S110: Obtain the current AC voltage sampling value V before the inverter is connected to the grid. ac_AD1 ;

[0080] S120: Determine the current AC voltage sampling value V ac_AD1 Is it a positive zero crossing? If yes, proceed to step S130; otherwise, proceed to step S150.

[0081] S130: Determine the current AC voltage sampling value V ac_AD1 Is this the first positive zero crossing? If yes, proceed to step S140; otherwise, proceed to step S180.

[0082] S140: Reset N to 0, where N is a natural number;

[0083] S150: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD1 ;

[0084] S160: Calculate and obtain the pre-stored compensation value PreDeltaV N-2 And store;

[0085] S170: Update N=N+1, proceed to step S110;

[0086] S180: End.

[0087] Its principle and advantages are the same as the control method of the inverter mentioned above, and will not be repeated here.

[0088] Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the present disclosure as defined by the appended claims.

[0089] Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, apparatuses, methods, and steps described in the specification. As will be readily understood by those skilled in the art from the disclosure of this publication, processes, machines, manufactures, compositions of matter, means, methods, or steps that perform substantially the same function, currently exist or will be developed or implemented thereafter, will yield substantially the same results as the corresponding embodiments described herein that are available according to this disclosure. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, apparatuses, methods, or steps within their scope.

Claims

1. A control method for an inverter, characterized in that, include: S10: Obtain the current AC voltage sampling value V when the inverter is in grid-connected operation. ac_AD2 ; S20: Determine the current AC voltage sampling value V ac_AD2 Is it a positive zero crossing? If yes, proceed to step S30; otherwise, proceed to step S40. S30: Reset N to 0, where N is a natural number, and proceed to step S10; S40: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD2 ; S50: Calculate and obtain the current compensation value NewDeltaV N-2 =V N - V N-2 ; S60: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N-2 ; S70: Based on the current compensation value NewDeltaV N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 ; S80: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N And based on the current AC voltage sample value V ac_AD2 and the pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL ; S90: Output the current actual AC voltage feedback value V AC_CONTROL Then update N=N+1 and proceed to step S10.

2. The control method for the inverter according to claim 1, characterized in that, Also includes: S110: Obtain the current AC voltage sampling value V before the inverter is connected to the grid. ac_AD1 ; S120: Determine the current AC voltage sampling value V ac_AD1 Is it a positive zero crossing? If yes, proceed to step S130; otherwise, proceed to step S150. S130: Determine the current AC voltage sampling value V ac_AD1 Is this the first positive zero crossing? If yes, proceed to step S140; otherwise, proceed to step S180. S140: Reset N to 0, where N is a natural number; S150: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD1 ; S160: Calculate and obtain the pre-stored compensation value PreDeltaV N-2 And store; S170: Update N=N+1, proceed to step S110; S180: End.

3. The control method for the inverter according to claim 2, characterized in that, The process after step S90 also includes: S100: The controller receives the current actual AC voltage feedback value V. AC_CONTROL And based on the current actual AC voltage feedback value V AC_CONTROL Output control signals for the switching of the inverter's main circuit.

4. The control method for the inverter according to claim 3, characterized in that, Step S60 includes: S61: Obtain the current AC voltage sampling value V ac_AD2 The corresponding phase value; S62: Retrieve the pre-stored compensation value PreDeltaV corresponding to the phase value shifting forward by two phase intervals from the memory. N-2 .

5. The control method for the inverter according to claim 4, characterized in that, Step S70 is: The current compensation value NewDeltaV is determined by a filtering unit. N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 .

6. The control method for the inverter according to claim 5, characterized in that, The filtering unit executes DeltaV. N-2 = PreDeltaV N-2 * a + NewDeltaV N-2 * (1-a), where a is between 0 and 1.

7. The control method for the inverter according to claim 6, characterized in that, Step S80 is: According to formula V AC_CONTROL =V ac_AD2 -PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL .

8. An inverter, characterized in that, include: The inverter main circuit includes at least one switching transistor for converting the DC power received at its DC terminal into AC power output at its AC terminal. A voltage sampling circuit, connected to the AC terminal of the inverter main circuit, is used to obtain AC voltage sampling values; The memory stores an array of pre-stored compensation values ​​for one power frequency cycle. The processing unit updates the pre-stored compensation value array in the memory and, based on the current AC voltage sampling value V obtained by the inverter operating in grid-connected mode, updates the pre-stored compensation value array in the memory. ac_AD2 and the current AC voltage sample value V in the memory ac_AD2 The corresponding pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL ; The controller receives the current actual AC voltage feedback value V. AC_CONTROL The output controls the switching signals of the switching transistors in the main circuit of the inverter.

9. The inverter according to claim 8, characterized in that, The processing unit performs: S10: Obtain the current AC voltage sampling value V when the inverter is in grid-connected operation. ac_AD2 ; S20: Determine the current AC voltage sampling value V ac_AD2 Is it a positive zero crossing? If yes, proceed to step S30; otherwise, proceed to step S40. S30: Reset N to 0, where N is a natural number, and proceed to step S10; S40: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD2 ; S50: Calculate and obtain the current compensation value NewDeltaV N-2 =V N - V N-2 ; S60: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N-2 ; S70: Based on the current compensation value NewDeltaV N-2 and the pre-stored compensation value PreDeltaV N-2 Obtain updated compensation value DeltaV N-2 And update the pre-stored compensation value PreDeltaV in memory. N-2 = DeltaV N-2 ; S80: Obtain the current AC voltage sample value V from the memory. ac_AD2 The corresponding pre-stored compensation value PreDeltaV N And based on the current AC voltage sample value V ac_AD2 and the pre-stored compensation value PreDeltaV N Obtain the current actual AC voltage feedback value V AC_CONTROL ; S90: Output the current actual AC voltage feedback value V AC_CONTROL Then update N=N+1 and proceed to step S10.

10. The inverter according to any one of claims 8 or 9, characterized in that, The processing unit also performs: S110: Obtain the current AC voltage sampling value V before the inverter is connected to the grid. ac_AD1 ; S120: Determine the current AC voltage sampling value V ac_AD1 Is it a positive zero crossing? If yes, proceed to step S130; otherwise, proceed to step S150. S130: Determine the current AC voltage sampling value V ac_AD1 Is this the first positive zero crossing? If yes, proceed to step S140; otherwise, proceed to step S180. S140: Reset N to 0, where N is a natural number; S150: Update stored value V N-2 =V N-1 V N-1 =V N V N =V ac_AD1 ; S160: Calculate and obtain the pre-stored compensation value PreDeltaV N-2 And store; S170: Update N=N+1, proceed to step S110; S180: End.

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