A single-phase flyback inverter grid-connected control system and method

Abstract

This invention discloses a grid-connected control system and method for a single-phase flyback inverter. The system includes: a single-phase phase-locked loop (PLL) for acquiring the voltage signal of a single-phase power grid and obtaining an inner-loop current control reference signal based on the voltage signal; a linear active disturbance rejection controller (ADC) for acquiring the current signal of a single-phase power grid and obtaining a control quantity based on the current signal and the inner-loop current control reference signal; a PWM modulation module for obtaining a drive signal for controlling the primary-side main switch of the single-phase flyback inverter based on the control quantity; and a zero-crossing comparator for obtaining a drive signal for controlling the inverter bridge switch of the single-phase flyback inverter based on the control quantity. This invention acquires the voltage signal of the power grid through a single-phase PLL and generates an inner-loop current control reference signal. It also designs a feedforward compensation stage based on the reference current to improve the linear ADC, thereby enhancing the current control performance of the single-phase flyback grid-connected inverter. This invention can be widely applied in the field of flyback inverter control technology.

Description

Technical Field

[0001] This invention relates to the field of flyback inverter control technology, and in particular to a grid-connected control system and method for a single-phase flyback inverter. Background Technology

[0002] Currently, most grid-connected control systems use traditional PI-type phase-locked loops to achieve phase tracking. Traditional phase-locked loops can achieve good phase tracking capability when running smoothly, but when the grid voltage is disturbed, the phase and frequency information output by them deviates. This is because the control performance of traditional PI-type phase-locked loops is limited and their ability to cope with disturbances is insufficient.

[0003] Active disturbance rejection (ADRROC) methods are highly adaptable and widely applicable, suitable for various control scenarios. However, due to their internal structure, while the observation performance of the extended state observer improves with increasing order, its hysteresis also increases. Therefore, to some extent, the order of the ADRROC also becomes a limiting factor in its capabilities. In control scenarios with high speed requirements, the control performance of high-order ADRROCs is not ideal. Summary of the Invention

[0004] In order to at least partially solve one of the technical problems existing in the prior art, the purpose of this invention is to provide a grid-connected control system and method for a single-sided flyback inverter.

[0005] The technical solution adopted in this invention is:

[0006] A grid-connected control system for a single-phase flyback inverter includes:

[0007] A single-phase phase-locked loop is used to acquire the voltage signal of a single-phase power grid and obtain the inner loop current control reference signal based on the voltage signal.

[0008] A linear active disturbance rejection controller is used to acquire the current signal of a single-phase power grid and obtain the control quantity u based on the current signal and the inner loop current control reference signal.

[0009] The PWM modulation module is used to obtain the drive signal for controlling the primary-side main switch of the single-sided flyback inverter according to the control quantity u.

[0010] A zero-crossing comparator is used to obtain the drive signal for controlling the inverter bridge switch of the single-sided flyback inverter based on the control quantity u.

[0011] Furthermore, the single-phase phase-locked loop includes an orthogonal signal generation module, a coordinate transformation module, a digital signal processing module, an active disturbance rejection controller module, a limiting module, an integrator module, and a sine calculation module;

[0012] The single-phase phase-locked loop operates as follows:

[0013] The voltage signal V0 is input into the quadrature signal generation module, which outputs two orthogonal signals V with the same amplitude. α and V β , where signal V β and V α The phase difference is 90°;

[0014] The coordinate transformation module transforms the orthogonal signal V α and V β And perform coordinate transformation on the 0 signal to obtain the signal V under the rotating coordinate axis. q and V d ;

[0015] The digital signal processing module will process signal V q Perform phase-locked control and synchronize with the reference signal V. q * The error signal e is obtained by subtracting the subtrahend.

[0016] After the error signal e passes through the active disturbance rejection controller module and the limiting module, it is input into the integration module to obtain the power grid phase information ωt;

[0017] The grid phase information ωt is calculated by the sine wave calculation module and then multiplied by the gain k to obtain the inner loop current control reference signal i. r .

[0018] Furthermore, the transfer function of the single-phase phase-locked loop is as follows:

[0019]

[0020]

[0021]

[0022] Where, α i To track the differentiator parameters, k i β is the parameter of the error feedback control law. i For the extended state observer parameters, l i t i p i and q i These are all simplified parameters for the controller;

[0023] p1=α1k1

[0024] p2=α1k2

[0025] p3=α1k3

[0026] q1=α1

[0027] q2=α2

[0028] q3=α3

[0029] l1=-k1β4

[0030] l2=k1β3-k2β4

[0031] l3=k1β2+k2β3-k3β4

[0032] l4=k1β1+k2β2+k3β3-β4

[0033] t1=-β4b0

[0034] t2=β3b0

[0035] t3=β2b0

[0036] t4=β1b0

[0037] t5=b0

[0038] Furthermore, the orthogonal signal generation module is implemented using a second-order generalized integrator.

[0039] Furthermore, the expression for the coordinate transformation module is as follows:

[0040]

[0041] In the formula, v a Indicates signal V α v b Indicates signal V β v c This indicates a 0 signal.

[0042] Furthermore, the linear active disturbance rejection controller includes a third-order tracking differentiator, a fourth-order linear extended observer, and a linear error feedback control law;

[0043] The linear active disturbance rejection controller operates as follows:

[0044] The inner loop current control reference signal i r The input to the third-order tracking differentiator outputs a multi-order differential signal m1 = i r ,

[0045] According to the inner loop current control reference signal i r The current signal i output by a single-flyback inverter o After compensation and correction, the compensated current signal is obtained. The compensated current signal is then input into a fourth-order linear extended observer, which outputs the observations z1, z2, z3, and z4.

[0046] The observed quantities z1, z2, and z3 are combined with the differential signals of each order generated by the third-order tracking differentiator to obtain the error signals e1, e2, and e3 of each order.

[0047] The error signals e1, e2, and e3 of each order are input into the linear error feedback control law, and the initial control quantity u is output. o ;

[0048] The observed quantity z4 is compared with the initial control quantity u. o Adjustments are made to obtain the final control quantity u.

[0049] Furthermore, the expression for the compensated current signal is:

[0050] i′ o =t1i r +t2i o

[0051] Where t1 and t2 are weights.

[0052] Furthermore, the observation z4 is used to adjust the initial control quantity u. o The expression for adjustment is:

[0053]

[0054] Where b0 is the controller parameter.

[0055] Furthermore, the single-sided flyback inverter includes a transformer, a primary-side main switch, diodes, and an inverter bridge;

[0056] The primary-side main switch is connected in series with the primary side of the transformer. The secondary side of the transformer is connected in series with a diode and then in parallel with the inverter bridge. The inverter bridge consists of two sets of transistors connected in parallel, each set of transistors including two transistors connected in series. The inverter bridge is connected to a single-phase power grid through a filter.

[0057] Another technical solution adopted in this invention is:

[0058] A grid-connected control method for a single-phase flyback inverter includes the following steps:

[0059] The voltage signal of a single-phase power grid is acquired, the voltage signal is input into a single-phase phase-locked loop, and the inner loop current control reference signal is output.

[0060] The current signal of a single-phase power grid is acquired, and the current signal and the inner loop current control reference signal are input into a linear active disturbance rejection controller, which outputs the acquired control quantity u.

[0061] The control quantity u is input into the PWM modulation module, and the output is a drive signal that controls the primary-side main switch of the single-sided flyback inverter.

[0062] The control quantity u is input to the zero-crossing comparator, which outputs a drive signal to control the inverter bridge switch of the single-sided flyback inverter.

[0063] The beneficial effects of this invention are: This invention obtains the voltage signal of the power grid through a single-phase phase-locked loop and generates an inner-loop current control reference signal. It designs a feedforward compensation link based on the reference current to improve the linear active disturbance rejection controller, which can enhance the current control effect of the single-phase flyback grid-connected inverter. Attached Figure Description

[0064] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following description is provided with accompanying drawings of the relevant technical solutions in the embodiments of the present invention or the prior art. It should be understood that the accompanying drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0065] Figure 1 This is a schematic diagram of the grid-connected control system for a single-phase flyback inverter according to an embodiment of the present invention;

[0066] Figure 2 This is a schematic diagram of the structure of the linear active disturbance rejection controller in an embodiment of the present invention;

[0067] Figure 3 This is a schematic diagram of the structure of a single-phase phase-locked loop in an embodiment of the present invention;

[0068] Figure 4 This is a schematic diagram of the structure of the second-order generalized integrator in an embodiment of the present invention;

[0069] Figure 5 This is a block diagram of the transfer function structure of a single-phase phase-locked loop in an embodiment of the present invention;

[0070] Figure 6 This is a Bode diagram of a single-phase phase-locked loop in an embodiment of the present invention;

[0071] Figure 7 This is a comparison of the frequency curves of the simulation results of the grid-connected control system of a single-flyback inverter according to an embodiment of the present invention under the condition of frequency mutation and the traditional PI control method.

[0072] Figure 8 This is a comparison of the output current waveforms of the single-flyback inverter grid-connected control system of this invention under frequency mutation conditions with the traditional PI control method simulation results.

[0073] Figure 9This is a comparison of the phase curves of the single-flyback inverter grid-connected control system of this invention under phase change conditions with the traditional PI control method simulation results.

[0074] Figure 10 This is a comparison of the output current waveforms of the single-flyback inverter grid-connected control system under phase change conditions and the traditional PI control method, according to simulation results of an embodiment of the present invention. Detailed Implementation

[0075] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0076] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0077] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0078] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0079] like Figure 1 As shown, a single-phase flyback inverter grid-connected system includes:

[0080] The DC input terminal is used to provide DC current to the flyback inverter.

[0081] The DC voltage regulator capacitor C is used to make the input voltage more stable.

[0082] A single-phase flyback inverter is used to convert direct current (DC) into sinusoidal alternating current (AC).

[0083] LC filters are used to filter out harmonics in the output AC signal;

[0084] Single-phase power grid.

[0085] See Figure 1 This embodiment provides a grid-connected control system for a single-phase flyback inverter, including:

[0086] A single-phase phase-locked loop (ADRC-PLL) is used to acquire the voltage signal of a single-phase power grid and obtain the inner loop current control reference signal based on the voltage signal.

[0087] A linear active disturbance rejection controller is used to acquire the current signal of a single-phase power grid and obtain the control quantity u based on the current signal and the inner loop current control reference signal.

[0088] The PWM modulation module is used to obtain the drive signal for controlling the primary-side main switch of the single-sided flyback inverter according to the control quantity u.

[0089] A zero-crossing comparator is used to obtain the drive signal for controlling the inverter bridge switch of the single-sided flyback inverter based on the control quantity u.

[0090] In this embodiment, the flyback inverter employs current control, and an improved phase-locked loop based on self-disruption rejection is used to acquire grid phase information and generate a current reference signal i. r The generated current reference signal i r The output current of the flyback inverter, i.e., the grid-connected current, is... o An input active disturbance rejection controller is used to generate control signals to drive the flyback inverter.

[0091] As an optional implementation method, such as Figure 3 As shown, the single-phase phase-locked loop includes an orthogonal signal generation module, a coordinate transformation module, a digital signal processing module, an active disturbance rejection controller module, a limiting module, an integrator module, and a sine calculation module;

[0092] The single-phase phase-locked loop operates as follows:

[0093] The voltage signal V0 is input into the quadrature signal generation module, which outputs two orthogonal signals V with the same amplitude. α and V β , where signal V α and V β The phase difference is 90°, and the signal V α and V β Maintain consistency. Specifically, V α =V0,V βPhase lag V α 90°.

[0094] The coordinate transformation module transforms the orthogonal signal V α and V β And perform coordinate transformation on the 0 signal to obtain the signal V under the rotating coordinate axis. q and V d ;

[0095] The digital signal processing module will process signal V q Perform phase-locked control and synchronize with the reference signal V. q * The error signal e is obtained by subtracting the subtrahend.

[0096] The error signal e is passed through the Active Disturbance Rejection Controller (ADRC) module and the limiting module, and then input into the integration module to obtain the power grid phase information ωt;

[0097] The grid phase information ωt is calculated by the sine wave calculation module and then multiplied by the gain k to obtain the inner loop current control reference signal i. r .

[0098] The inner loop current control reference signal i r and grid-connected current i o Input the inner-loop active disturbance rejection controller to obtain the control quantity u. Input the control quantity u into the PWM modulation stage to obtain the primary-side main switch drive signal S of the flyback inverter. Input the control quantity u into the zero-crossing comparator to obtain the inverter bridge switch drive signals S1 to S4.

[0099] As an optional implementation, see [link to previous document]. Figure 4 The orthogonal signal generation module is implemented using a second-order generalized integrator.

[0100] As an optional implementation, see [link to previous document]. Figure 3 The second-order generalized integrator outputs an orthogonal signal V. α and V β Afterwards, a coordinate transformation process is required to convert from the three-phase ABC coordinate system to the two-phase synchronous rotating (dq) coordinate system. Specifically, the expression for this coordinate transformation module is as follows:

[0101]

[0102] As an optional implementation, see [link to implementation details]. Figure 2 The aforementioned linear active disturbance rejection controller includes a third-order tracking differentiator (TD), a fourth-order linear extended observer (LESO), and a linear error feedback control law (LSEF). Among these, Figure 2 The flyback inverter in the text refers to a flyback inverter.

[0103] Design a third-order tracking differentiator (TD), i r Using the reference signal, output a multi-order differential signal.

[0104]

[0105] Design a fourth-order linear extended state observer (LESO), i o The signal is the current output of the single-phase grid-connected inverter, u is the control quantity generated by the active disturbance rejection controller, and the observer realizes the observed quantity z1 = i. o z2, z3, and z4 are differential signals of various orders. z1 to z3 are used to combine with the differential signals of various orders generated by the tracking differentiator to obtain error signals of various orders, so as to adjust the controlled object from the tracking error differential level. z4 is used to further correct the control signal u.

[0106]

[0107] Using reference current i r The feedforward method applies the grid-connected current i to the input third-order linear extended state observer. o Compensation and correction are performed to improve the observation performance of the third-order linear extended state observer. That is, i′ o =t1i r +t2i o

[0108] Design a linear error feedback control law (LSEF), and sum the product of each order error signal e with its corresponding gain to obtain the initial control quantity u. o ,u o The final control quantity u is obtained by adjusting z4.

[0109] e i =z i -m i i = 1, 2, 3

[0110] u0=∑k i e i i = 1, 2, 3

[0111]

[0112] As an optional implementation, the active disturbance rejection controller module in a single-phase phase-locked loop can be adopted with... Figure 2 The circuit structure of the linear active disturbance rejection controller shown is used to implement this.

[0113] See Figure 5 The transfer function of this single-phase phase-locked loop is as follows:

[0114]

[0115]

[0116]

[0117] p1=α1k1

[0118] p2=α1k2

[0119] p3=α1k3

[0120] q1=α1

[0121] q2=α2

[0122] q3=α3

[0123] l1=-k1β4

[0124] l2=k1β3-k2β4

[0125] l3=k1β2+k2β3-k3β4

[0126] l4=k1β1+k2β2+k3β3-β4

[0127] t1=-β4b0

[0128] t2=β3b0

[0129] t3=β2b0

[0130] t4=β1b0

[0131] t5=b0

[0132] Plot its frequency response curve, i.e., the Bode plot. Figure 6 As shown in the figure, at its operating frequency of 314 rad / s (50 Hz), its amplitude-frequency characteristic is positive, and both its amplitude margin and phase margin are positive. It exhibits stable characteristics at the operating frequency. In the high-frequency range, its amplitude-frequency characteristic is negative, which has an attenuation effect on high-frequency harmonics and has a good high-frequency harmonic suppression capability.

[0133] Simulation circuits were built using the MATLAB / SIMULINK platform. The control system circuit based on the proposed method and the traditional PI control system circuit were constructed respectively. At 0.115s, the simulated power grid operating frequency changed abruptly from 50Hz to 60Hz. The frequency curves of the simulation results are shown in the figure below. Figure 7 As shown. By Figure 7 As can be seen, under traditional PI control, the output frequency curve exhibits jitter and excessive overshoot. However, under the system control proposed in this embodiment, the output frequency curve shows less fluctuation and no significant overshoot, demonstrating better control performance. The simulation results and output current curve comparison are shown in the figure below. Figure 8 As shown. By Figure 8 As can be seen, at the start of the simulation, the traditional PI control method exhibits significant jitter and overshoot, while these effects are much weaker under the control of this invention. At frequency abrupt changes, the output current waveform is significantly distorted with a large amplitude under the traditional PI control method, while the distortion amplitude is smaller and the waveform recovers more quickly under the control of this invention.

[0134] Simulation circuits were built using the MATLAB / SIMULINK platform. The control system circuit based on the proposed method and the traditional PI control system circuit were constructed respectively. A 30-degree phase abrupt change disturbance in the power grid was simulated at 0.04s. The phase curve comparison of the simulation results is shown in the figure below. Figure 9 As shown. By Figure 9 As can be seen, the two control methods do not show a significant difference in the phase curves; both phase curves exhibit distortion, and both recover within half a cycle. A comparison of the simulation results' output current curves is shown below. Figure 10 As shown. By Figure 10 As can be seen, at the start of the simulation, there is a significant overshoot under the traditional PI control method, while the effect is much weaker under the control of this invention. At the phase abrupt change, the output current waveform is significantly distorted under the traditional PI control method, while the distortion amplitude is smaller and the waveform recovers faster under the control of this invention.

[0135] In summary, this embodiment has at least the following advantages and beneficial effects compared to the corresponding technology:

[0136] (1) This invention improves the linear active disturbance rejection controller, enhances the control accuracy and disturbance rejection capability of the linear active disturbance rejection controller, and realizes the grid-connected current control method of flyback inverter based on the improved linear active disturbance rejection controller.

[0137] (2) The present invention improves the single-phase phase-locked loop (PLL) by adopting the proposed improved linear active disturbance rejection control method, derives the transfer function of the control system, draws Bode plots to analyze the feasibility of the proposed method from a theoretical perspective, and verifies the feasibility of the method through simulation experiments.

[0138] (3) The present invention applies the anti-disturbance characteristics of the proposed improved active disturbance rejection control method to a single-phase phase-locked loop to improve the phase tracking effect of the single-phase phase-locked loop and thus improve the current control effect of the single-phase exciter grid-connected inverter.

[0139] (4) This invention uses the reference current signal i r For the grid-connected current i of the input third-order linear extended state observer o Compensation and correction were performed to improve the observation performance of the third-order linear extended state observer.

[0140] This embodiment also provides a grid-connected control method for a single-phase flyback inverter, including the following steps:

[0141] S1. Acquire the voltage signal of a single-phase power grid, input the voltage signal into a single-phase phase-locked loop, and output the inner loop current control reference signal;

[0142] S2. Acquire the current signal of a single-phase power grid, input the current signal and the inner loop current control reference signal into the linear active disturbance rejection controller, and output the acquired control quantity u;

[0143] S3. Input the control quantity u into the PWM modulation module and output the drive signal to control the primary main switch of the single-sided flyback inverter;

[0144] S4. Input the control quantity u into the zero-crossing comparator and output the drive signal to control the inverter bridge switch of the single-sided flyback inverter.

[0145] The grid-connected control method for a single-flyback inverter in this embodiment corresponds to the grid-connected control system for a single-flyback inverter described above. Therefore, the method in this embodiment possesses the functions and beneficial effects of the system embodiment described above.

[0146] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0147] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0148] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A grid-connected control system for a single-phase flyback inverter, characterized in that, include: A single-phase phase-locked loop is used to acquire the voltage signal of a single-phase power grid and obtain the inner loop current control reference signal based on the voltage signal. A linear active disturbance rejection controller is used to acquire the current signal of a single-phase power grid and obtain the control quantity u based on the current signal and the inner loop current control reference signal. The PWM modulation module is used to obtain the drive signal for controlling the primary-side main switch of the single-sided flyback inverter according to the control quantity u. A zero-crossing comparator is used to obtain the drive signal for controlling the inverter bridge switch of the single-sided flyback inverter based on the control quantity u. The single-phase phase-locked loop includes an orthogonal signal generation module, a coordinate transformation module, a digital signal processing module, an active disturbance rejection controller module, a limiting module, an integrator module, and a sine calculation module; The single-phase phase-locked loop operates as follows: The voltage signal V0 is input into the quadrature signal generation module, which outputs two orthogonal signals V with the same amplitude. α and V β , where signal V α and V β The phase difference is 90°; The coordinate transformation module transforms the orthogonal signal V α and V β And perform coordinate transformation on the 0 signal to obtain the signal V under the rotating coordinate axis. q and V d ; The digital signal processing module will process signal V q Perform phase-locked control and synchronize with the reference signal V. q * The error signal e is obtained by subtracting the subtrahend. The error signal e is passed through the active disturbance rejection controller module and the limiting module, and then input into the integration module to obtain the grid phase information ωt. The grid phase information ωt is then calculated by the sine wave calculation module and multiplied by the gain k to obtain the inner loop current control reference signal i. r .

2. The grid-connected control system for a single-phase flyback inverter according to claim 1, characterized in that, The transfer function of the single-phase phase-locked loop is as follows: Among them, l i t i p i and q i These are all simplified parameters for the controller.

3. The grid-connected control system for a single-phase flyback inverter according to claim 1, characterized in that, The orthogonal signal generation module is implemented using a second-order generalized integrator.

4. A grid-connected control system for a single-phase flyback inverter according to claim 1, characterized in that, The expression for the coordinate transformation module is as follows: In the formula, v a Indicates signal V α v b Indicates signal V β v c This indicates a 0 signal.

5. A grid-connected control system for a single-phase flyback inverter according to claim 1, characterized in that, The linear active disturbance rejection controller includes a third-order tracking differentiator, a fourth-order linear extended observer, and a linear error feedback control law; The linear active disturbance rejection controller operates as follows: The inner loop current control reference signal i r The input to the third-order tracking differentiator outputs a multi-order differential signal m1 = i r , According to the inner loop current control reference signal i r The current signal i output by a single-flyback inverter o After compensation and correction, the compensated current signal is obtained. The compensated current signal is then input into a fourth-order linear extended observer, which outputs the observations z1, z2, z3, and z4. The observed quantities z1, z2, and z3 are combined with the differential signals of each order generated by the third-order tracking differentiator to obtain the error signals e1, e2, and e3 of each order. The error signals e1, e2, and e3 of each order are input into the linear error feedback control law, and the initial control quantity u is output. o ; The observed quantity z4 is compared with the initial control quantity u. o Adjustments are made to obtain the final control quantity u.

6. A grid-connected control system for a single-phase flyback inverter according to claim 5, characterized in that, The expression for the compensated current signal is: i' o =t1i r +t2i o Where t1 and t2 are weights.

7. A grid-connected control system for a single-phase flyback inverter according to claim 5, characterized in that, The observation z4 is compared with the initial control quantity u o The expression for adjustment is: Where b0 is the controller parameter.

8. A grid-connected control system for a single-phase flyback inverter according to claim 1, characterized in that, The single-sided flyback inverter includes a transformer, a primary-side main switch, diodes, and an inverter bridge; the primary-side main switch is connected in series with the primary side of the transformer, and the secondary side of the transformer is connected in series with the diodes and then in parallel with the inverter bridge; The inverter bridge consists of two sets of transistors connected in parallel, each set including two transistors connected in series. The inverter bridge is connected to a single-phase power grid through a filter.

9. A grid-connected control method for a single-phase flyback inverter, applied to the system described in any one of claims 1-8, characterized in that, Includes the following steps: The voltage signal of a single-phase power grid is acquired, the voltage signal is input into a single-phase phase-locked loop, and the inner loop current control reference signal is output. The current signal of a single-phase power grid is acquired, and the current signal and the inner loop current control reference signal are input into a linear active disturbance rejection controller, which outputs the acquired control quantity u. The control quantity u is input into the PWM modulation module, and the output is a drive signal that controls the primary-side main switch of the single-sided flyback inverter. The control quantity u is input to the zero-crossing comparator, which outputs a drive signal to control the inverter bridge switch of the single-sided flyback inverter.

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