Control method for power factor of flyback inverter during grid connection, and controller

Abstract

The present application discloses a control method for a power factor of a flyback inverter during grid connection, and a controller. The method comprises: acquiring a working electrical signal of a target power grid; performing phase locking on the working electrical signal to obtain a voltage modulation wave signal; on the basis of a power factor angle corresponding to a preset power factor, performing phase shift on the voltage modulation wave signal to obtain a current modulation wave signal; selecting part of the waveform of the voltage modulation wave signal as a correction waveform of the current modulation wave signal in a corresponding time period; fusing the correction waveform with part of the waveform of the current modulation wave signal to obtain a corrected modulation wave signal waveform; and controlling a flyback inverter to output, to the target power grid or an electric device, a target alternating current corresponding to the corrected modulation wave signal waveform. By using the corrected modulation wave signal generated by the method of the present application to control the flyback inverter, accurate adjustment of the power factor of the flyback inverter during grid connection can be achieved, and harmonics are reduced.

Description

Control method and controller for grid-connected power factor of flyback inverter TECHNICAL FIELD

[0001] The present application relates to the technical field of flyback inverter grid connection, and particularly relates to a control method and controller for grid-connected power factor of flyback inverter. BACKGROUND

[0002] Based on renewable solar energy, photovoltaic power generation can produce more electric energy, thereby solving the growing demand for electricity. Photovoltaic power generation often needs to convert direct current into alternating current based on an inverter, and the alternating current is connected to the corresponding power grid.

[0003] An inverter is a device that converts direct current (DC) into alternating current (AC). A general inverter uses a technology called PWM (pulse width modulation) or SPWM (sine pulse width modulation) to generate alternating current. In the process of using the SPWM technology, the inverter simulates a sine waveform by rapidly switching a switching device (such as an IGBT). Because the switching speed of the switching device is very fast, the inverter will generate high-frequency harmonics when switching the switching device to simulate the sine wave. And the generated alternating current will generate active power and reactive power when connected to the grid, and the active power and reactive power will be out of sync or have a phase angle, resulting in a decrease in power factor.

[0004] In related technologies, the output of the flyback circuit usually uses a diode. This circuit can achieve a grid-connected current with a power factor of 1, but due to the unidirectional conduction characteristic of the diode, energy cannot be transmitted from the grid to the photovoltaic side, and the power factor adjustment of the inverter grid connection cannot be achieved. There is no detailed disclosure of a special flyback micro power factor adjustment inverter grid connection control method in the related art.

[0005] SUMMARY

[0006] The main purpose of the present application is to provide a control method and controller for grid-connected power factor of flyback inverter, which aims to solve the problem that there is no detailed disclosure of a special flyback micro power factor adjustment inverter grid connection control method in the prior art.

[0007] To achieve the above-mentioned purpose, the present application provides a control method for grid-connected power factor of flyback inverter, which comprises:

[0008] obtaining a working electrical signal of a target power grid;

[0009] phase-locked to the working electrical signal to obtain a voltage modulation wave signal consistent with the phase and frequency of the working electrical signal;

[0010] The voltage modulation wave signal is phase-shifted according to the power factor angle corresponding to the preset power factor, to obtain a current modulation wave signal consistent in frequency with the voltage modulation wave signal and having a phase angle difference relative to the voltage modulation wave signal; the waveforms of the voltage modulation wave signal and the current modulation wave signal are both sinusoidal modulation waveforms.

[0011] The waveforms of the voltage modulation wave signal and the current modulation wave signal and the intersection of the two waveforms are obtained, and a partial waveform of the voltage modulation wave signal is selected as a corrected waveform of the current modulation wave signal in a corresponding time period.

[0012] The corrected waveform is fused with a partial waveform of the current modulation wave signal to obtain a corrected modulation wave signal waveform.

[0013] The flyback inverter is controlled to output target alternating current corresponding to the corrected modulation wave signal waveform to a target power grid or a power consumption device.

[0014] In some embodiments, the voltage modulation wave signal is phase-shifted according to the power factor angle corresponding to the preset power factor, to obtain a current modulation wave signal consistent in frequency with the voltage modulation wave signal and having a phase angle difference relative to the voltage modulation wave signal, including:

[0015] The phase difference angle of the current modulation wave signal relative to the voltage modulation wave signal is calculated according to the power factor angle corresponding to the preset power factor.

[0016] The phase of the voltage modulation wave signal is operated with the phase difference angle to obtain the phase of the current modulation wave signal.

[0017] The voltage modulation wave signal is phase-shifted according to the phase of the current modulation wave signal to obtain the current modulation wave signal.

[0018] In some embodiments, the voltage modulation wave signal is phase-shifted according to the power factor angle corresponding to the preset power factor, to obtain a current modulation wave signal consistent in frequency with the voltage modulation wave signal and having a phase angle difference relative to the voltage modulation wave signal, including:

[0019] When the load connected with the flyback inverter is an inductive load, the voltage modulation wave signal is phase-shifted in a lag direction according to the power factor angle corresponding to the preset power factor; or,

[0020] When the load connected with the flyback inverter is a capacitive load, the voltage modulation wave signal is phase-shifted in a lead direction according to the power factor angle corresponding to the preset power factor.

[0021] In some embodiments, the acquiring the waveform of the voltage modulation wave signal, the waveform of the current modulation wave signal, and the intersection of the two waveforms, selecting a partial waveform of the voltage modulation wave signal as a corrected waveform of the current modulation wave signal in a corresponding time period comprises:

[0022] When the current modulation wave signal lags behind the voltage modulation wave signal in phase, the intersection of the waveform of the current modulation wave signal and the waveform of the voltage modulation wave signal in a half cycle is acquired, and the waveform of the voltage modulation wave signal from the intersection to the zero-crossing point of the voltage modulation wave signal is taken as the corrected waveform of the current modulation wave signal;

[0023] When the current modulation wave signal leads the voltage modulation wave signal in phase, the intersection of the waveform of the voltage modulation wave signal and the waveform of the current modulation wave signal in a half cycle is acquired, and the waveform of the voltage wave signal from the zero-crossing point to the intersection is taken as the corrected waveform of the current modulation wave signal.

[0024] In some embodiments, the fusing the corrected waveform with the partial waveform of the current modulation wave signal to obtain the waveform of the corrected modulation wave signal comprises:

[0025] The intersection of the waveform of the current modulation wave signal and the waveform of the voltage modulation wave signal in a positive half cycle and the intersection in a negative half cycle are acquired;

[0026] When the current modulation wave signal lags behind the voltage modulation wave signal in phase, the time period of the intersection of the current modulation wave signal in the positive half cycle to the end point of the positive half cycle and the time period of the intersection in the negative half cycle to the end point of the negative half cycle are selected, and a logical AND operation is performed with a logical low level to obtain a first waveform signal; the time period of the intersection of the voltage modulation wave signal in the positive half cycle to the start point of the positive half cycle and the time period of the intersection in the negative half cycle to the start point of the negative half cycle are selected, and a logical AND operation is performed with a logical low level to obtain a second waveform signal; and the waveform of the corrected modulation wave signal is generated according to the first waveform signal and the second waveform signal;

[0027] When the current modulation wave signal leads the voltage modulation wave signal in phase, the time period of the intersection of the current modulation wave signal in the positive half cycle to the start point of the positive half cycle and the time period of the intersection in the negative half cycle to the start point of the negative half cycle are selected, and a logical AND operation is performed with a logical low level to obtain a first waveform signal; the time period of the intersection of the voltage modulation wave signal in the positive half cycle to the end point of the positive half cycle and the time period of the intersection in the negative half cycle to the end point of the negative half cycle are selected, and a logical AND operation is performed with a logical low level to obtain a second waveform signal; and the waveform of the corrected modulation wave signal is generated according to the first waveform signal and the second waveform signal.

[0028] In some embodiments, the generating a modified modulation wave signal according to the first waveform signal and the second waveform signal comprises:

[0029] performing a logical OR operation on the first waveform signal and the second waveform signal to obtain the modified modulation wave signal.

[0030] In some embodiments, after the step of fusing the modified waveform with the partial waveform of the current modulation wave signal to obtain the waveform of the modified modulation wave signal, the method further comprises:

[0031] generating a waveform of a sinusoidal modulation wave signal according to the waveform of the voltage modulation wave signal and the waveform of the current modulation wave signal, wherein the frequency and the phase of the sinusoidal modulation wave signal are consistent with the frequency and the phase of the modified modulation wave signal, respectively;

[0032] obtaining a carrier signal, the carrier signal being a triangular wave signal or a sawtooth wave signal;

[0033] superimposing the sinusoidal modulation wave signal and the carrier signal to obtain the modified modulation wave signal.

[0034] In some embodiments, the fusing the modified waveform with the partial waveform of the current modulation wave signal to obtain the waveform of the modified modulation wave signal comprises:

[0035] fusing the waveform of the current modulation wave in a positive half cycle with the modified waveform to obtain a waveform of a modified modulation wave signal in the positive half cycle;

[0036] fusing the waveform of the current modulation wave in a negative half cycle with the modified waveform to obtain a waveform of a modified modulation wave signal in the negative half cycle.

[0037] In some embodiments, the frequency of the working electrical signal is 50 Hz or 60 Hz.

[0038] The application also provides an inverter controller, the inverter controller storing a computer program, the computer program being executed by a processor to implement the control method of the flyback inverter grid-connected power factor as described above.

[0039] The application first acquires a voltage modulation wave signal according to a working signal of a target power grid, then obtains a current modulation wave signal by phase-shifting according to the voltage modulation wave signal and a preset power factor, uses part of the waveform of the voltage modulation wave signal as a correction waveform of the current modulation wave signal and fuses the waveform of the current modulation wave signal to obtain a waveform of a corrected modulation wave signal, and inputs the generated corrected modulation wave signal into the flyback inverter to accurately adjust the power factor when the flyback inverter is connected to the grid, reduce harmonics, improve the power efficiency and power quality of the power supply system, and ensure the economic and safe operation of the power grid and electrical equipment. BRIEF DESCRIPTION OF DRAWINGS

[0040] Fig. 1 is a flow chart of a control method of a power factor of a flyback inverter connected to a grid according to an embodiment of the application;

[0041] Fig. 2 is a flow chart of step S300 according to an embodiment of the application;

[0042] Fig. 3 is a waveform diagram of u1 and i1 when i1 lags u1 according to an embodiment of the application;

[0043] Fig. 4 is a timing sequence diagram composed of a waveform diagram of u1 and a corrected modulation wave signal and an SPWM waveform diagram of the corrected modulation wave signal when i1 lags u1 according to an embodiment of the application;

[0044] Fig. 5 is a waveform diagram of u1 and i1 when i1 leads u1 according to an embodiment of the application;

[0045] Fig. 6 is a timing sequence diagram composed of a waveform diagram of u1 and a corrected modulation wave signal and an SPWM waveform diagram of the corrected modulation wave signal when i1 leads u1 according to an embodiment of the application;

[0046] Fig. 7 is a flow chart of a method for generating a corrected modulation wave signal according to an embodiment of the application;

[0047] Fig. 8 is a flow chart of step S500 according to an embodiment of the application;

[0048] Fig. 9 is an information flow direction diagram of a control method of a power factor of a flyback inverter connected to a grid according to an embodiment of the application;

[0049] Fig. 10 is a circuit schematic diagram according to an embodiment of the application. DETAILED DESCRIPTION

[0050] The scheme in the embodiments of the application will be described in detail below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the application.

[0051] The descriptions related to “first”, “second” and the like in the embodiments of the present application are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0052] In view of the technical defects existing in the related technologies of the existing flyback micro-grid power factor adjustment, an embodiment of the present application provides a control method for the grid-connected power factor of a flyback inverter, referring to FIG. 1, the method comprises:

[0053] In the step S100, the working electrical signal of the target power grid is acquired; specifically, the power grid in the present application refers to a system composed of power plants, power transmission lines, substations and power distribution facilities and the like, and the power transmission in the power grid is in an alternating current mode, the current and voltage in the power grid are sinusoidal alternating currents, and the frequency is 50Hz or 60Hz. Therefore, the working electrical signal of the target power grid acquired in the present application is a sinusoidal alternating current signal with a frequency of 50Hz or 60Hz.

[0054] In the step S200, the working electrical signal is phase-locked to obtain a voltage modulation wave signal consistent with the phase and frequency of the working electrical signal; specifically, the phase-locked technology is a technology for controlling the phase of a controlled oscillator by a standard signal or an external signal, and is used to realize the phase synchronization with the external signal or track the frequency or phase of the external signal.

[0055] In the step S300, the voltage modulation wave signal is phase-shifted according to the power factor angle corresponding to the preset power factor to obtain a current modulation wave signal consistent with the frequency of the voltage modulation wave signal and having a phase angle difference with respect to the voltage modulation wave signal; the waveforms of the voltage modulation wave signal and the current modulation wave signal are both sinusoidal modulation waveforms; specifically, when the preset power factor is acquired, the corresponding power factor angle φ can be obtained through the preset power factor cosφ, and the power factor angle is equal to the difference between the phase angles of the two waveforms, that is, the current modulation wave signal leads or lags the voltage modulation wave signal by the power factor angle corresponding to the preset power factor.

[0056] Further, taking the preset power factor as 0.8, the grid working frequency as 50Hz, and the current modulation wave signal lagging the voltage modulation wave signal by the angle φ as an example, cosφ=0.8, and the corresponding power factor angle φ is about π / 5, so the angle by which the current modulation wave signal lags the voltage modulation wave signal is equal to the power factor angle corresponding to the preset power factor, both of which are about π / 5.

[0057] In the step S400, the waveforms of the voltage modulation wave signal and the current modulation wave signal and the intersection of the two waveforms are acquired, and part of the waveform of the voltage modulation wave signal is selected as the correction waveform of the current modulation wave signal in the corresponding time period;

[0058] Step S500, fuse the modified waveform with the partial waveform of the current modulation wave signal to obtain a modified modulation wave signal waveform; specifically, fuse the partial waveform of the voltage modulation wave signal with the partial waveform of the current modulation wave signal, and the obtained waveform of the modified modulation wave signal is equivalent to that the waveform of the current modulation wave signal borrows a part of the waveform of the voltage modulation wave signal, so the method for generating the waveform of the modified modulation wave signal in the present application can also be referred to as a u-borrow method.

[0059] Step S600, control the flyback inverter to output target alternating current corresponding to the modified modulation wave signal waveform to the target power grid or electrical equipment. It should be noted that the flyback inverter in the present application refers to an inverter using flyback switching power supply technology, and the flyback switching power supply refers to a switching power supply using a flyback high-frequency transformer to isolate the input and output circuits. The "flyback" (Flyback or flyback) specifically refers to when the switch tube is turned on, the output transformer acts as an inductor, and the electrical energy is converted into magnetic energy, at which time there is no current in the output circuit. On the contrary, when the switch tube is turned off, the output transformer releases energy, and the magnetic energy is converted into electrical energy, and there is current in the output circuit. Preferably, the flyback inverter in the present embodiment is a micro inverter, which can realize maximum power point tracking (MPPT) at the component level and has advantages over centralized inverters. In this way, the output power of each module can be optimized to maximize the overall output power.

[0060] Specifically, the present application first obtains a voltage modulation wave signal according to a working electrical signal of a target power grid, then obtains a current modulation wave signal by phase shifting according to the voltage modulation wave signal and a preset power factor, borrows a part of the waveform of the voltage modulation wave signal as a correction waveform of the current modulation wave signal and fuses it with the waveform of the current modulation wave signal to obtain a waveform of the modified modulation wave signal. When the generated modified modulation wave signal is input into the flyback inverter, the part of the current that cannot flow back due to the unidirectional conduction of the diode can be eliminated, so that the power factor can be accurately adjusted when the flyback inverter is connected to the grid. In addition, since the waveform of the modified modulation wave signal is the waveform of the current modulation wave signal borrowing a part of the waveform of the voltage modulation wave signal, the waveform of the modified modulation wave signal can be made smoother, thereby reducing harmonics and improving the power efficiency and power quality of the power supply system, and ensuring the economic and safe operation of the power grid and electrical equipment.

[0061] In some embodiments, referring to FIG. 2, step S300 includes:

[0062] Step S301, calculate the phase difference angle of the current modulation wave signal relative to the voltage modulation wave signal according to the power factor angle corresponding to the preset power factor;

[0063] Step S302, the phase of the voltage modulation wave signal is operated with the phase difference angle to obtain the phase of the current modulation wave signal;

[0064] Step S303, the phase of the current modulation wave signal is obtained by phase-shifting the voltage modulation wave signal according to the phase of the current modulation wave signal.

[0065] Specifically, when the preset power factor is obtained, the corresponding power factor angle φ can be obtained through the preset power factor cosφ, φ is the phase difference angle of the voltage modulation wave signal and the current modulation wave signal, and the phase of the current modulation wave signal relative to the voltage modulation wave signal can be obtained through operation. Phase advance or lag, so as to phase-shift the voltage modulation wave signal according to the phase, that is, to obtain the current modulation wave signal.

[0066] In some embodiments, step S300 includes:

[0067] When the load connected with the flyback inverter is an inductive load, the voltage modulation wave signal is phase-shifted in the lag direction according to the power factor angle corresponding to the preset power factor; or,

[0068] When the load connected with the flyback inverter is a capacitive load, the voltage modulation wave signal is phase-shifted in the lead direction according to the power factor angle corresponding to the preset power factor.

[0069] In some embodiments, referring to FIGS. 3-6, step S400 includes:

[0070] When the phase of the current modulation wave signal lags the phase of the voltage modulation wave signal, the intersection of the current modulation wave signal and the voltage modulation wave signal waveform in a half cycle is obtained, and the waveform of the voltage modulation wave signal from the intersection to the zero crossing point of the voltage modulation wave signal is taken as the modified waveform of the current modulation wave signal. Specifically, taking one integral period of 0-2π as an example, the waveforms of the voltage modulation wave signal from A to π and from B to 2π are selected as the modified waveforms of the current modulation wave signal.

[0071] When the phase of the current modulation wave signal leads the phase of the voltage modulation wave signal, the intersection of the voltage modulation wave signal waveform and the current modulation wave signal waveform in a half cycle is obtained, and the waveform of the voltage modulation wave signal from the zero crossing point to the intersection is taken as the modified waveform of the current modulation wave signal. Specifically, taking one integral period of 0-2π as an example, the waveforms of the voltage modulation wave signal from 0 to A and from π to B are selected as the modified waveforms of the current modulation wave signal.

[0072] In some embodiments, referring to FIGS. 4 and 6, taking one integral period as an example, step S500 includes:

[0073] The intersection (A point) of the current modulation wave signal waveform and the voltage modulation wave signal waveform in the positive half cycle and the intersection (B point) in the negative half cycle are obtained.

[0074] When the current modulation wave signal lags behind the voltage modulation wave signal, the time period from the intersection point to the end point of the positive half cycle and the time period from the intersection point to the end point of the negative half cycle of the current modulation wave signal in the positive half cycle and the negative half cycle are selected and logically ANDed with the logic low level to obtain the first waveform signal; the time period from the start point to the intersection point of the positive half cycle and the time period from the start point to the intersection point of the negative half cycle of the voltage modulation wave signal in the positive half cycle and the negative half cycle are selected and logically ANDed with the logic low level to obtain the second waveform signal; and the waveform of the corrected modulation wave signal is generated according to the first waveform signal and the second waveform signal.

[0075] Specifically, with reference to FIG. 4, in one integral period of the current modulation wave signal from φ to 2π+φ, the time period from A point to π in the positive half cycle of the current modulation wave signal and the time period from B point to 2π in the negative half cycle of the current modulation wave signal are selected and logically ANDed with the logic low level, so that the waveform corresponding to the time period from φ to A and the time period from π+φ to B of the current modulation wave signal is obtained as the first waveform signal; in one integral period of the voltage modulation wave signal from 0 to 2π, the time period from 0 to A in the positive half cycle of the voltage modulation wave signal and the time period from π to B in the negative half cycle of the voltage modulation wave signal are selected and logically ANDed with the logic low level, so that the waveform corresponding to the time period from A to π and the time period from B to 2π of the voltage modulation wave signal is obtained as the second waveform signal; and the first waveform signal and the second waveform signal are fused, so that the waveform of the corrected modulation wave signal is obtained.

[0076] When the current modulation wave signal leads the voltage modulation wave signal, the time period from the start point to the intersection point of the positive half cycle and the time period from the start point to the intersection point of the negative half cycle of the current modulation wave signal in the positive half cycle and the negative half cycle are selected and logically ANDed with the logic low level to obtain the first waveform signal; the time period from the intersection point to the end point of the positive half cycle and the time period from the intersection point to the end point of the negative half cycle of the current modulation wave signal in the positive half cycle and the negative half cycle are selected and logically ANDed with the logic low level to obtain the second waveform signal; and the waveform of the corrected modulation wave signal is generated according to the first waveform signal and the second waveform signal.

[0077] Specifically, referring to FIG. 6, in one integral period of the current modulation wave signal from -φ to 2π-φ, the time period of the current modulation wave signal from -φ to A in the positive half period of the current modulation wave signal and the time period of the current modulation wave signal from π-φ to B in the negative half period of the current modulation wave signal are selected to perform logical AND operation with the logic low level, so as to obtain the waveform corresponding to the time period of A to π-φ and the time period of B to 2π-φ of the current modulation wave signal, as the first waveform signal; in one integral period of the voltage modulation wave signal from 0 to 2π, the time period of the voltage modulation wave signal from A to π in the positive half period of the voltage modulation wave signal and the time period of the voltage modulation wave signal from B to 2π in the negative half period of the voltage modulation wave signal are selected to perform logical AND operation with the logic low level, so as to obtain the waveform corresponding to the time period of 0 to A and the time period of π to B of the voltage modulation wave signal, as the second waveform signal; then, the first waveform signal and the second waveform signal are fused, so as to obtain the waveform of the modified modulation wave signal.

[0078] In some embodiments, the waveform of the modified modulation wave signal is generated according to the first waveform signal and the second waveform signal, including:

[0079] The first waveform signal and the second waveform signal are logically ORed to obtain the modified modulation wave signal.

[0080] Specifically, since the first waveform signal and the second waveform signal correspond to different time periods respectively, the first waveform signal and the second waveform signal are logically ORed, so as to obtain the modified modulation wave signal.

[0081] In some embodiments, referring to FIG. 7, after the step S500, the method further includes:

[0082] In step A100, the waveform of the sinusoidal modulation wave signal is obtained according to the waveform of the voltage modulation wave signal and the waveform of the current modulation wave signal, wherein the frequency and the phase of the sinusoidal modulation wave signal are consistent with the frequency and the phase of the modified modulation wave signal respectively.

[0083] In step A200, a carrier signal is obtained, and the carrier signal is a triangular wave signal or a sawtooth wave signal.

[0084] In step A300, the sinusoidal modulation wave signal and the carrier signal are superimposed to obtain the modified modulation wave signal.

[0085] Specifically, the sinusoidal waveform of the modified modulation wave signal is generated by the waveform of the voltage modulation wave signal and the waveform of the current modulation wave signal, and the sinusoidal waveform of the modified modulation wave signal is superimposed with the high-frequency carrier signal, so as to obtain the modified modulation wave signal.

[0086] In some embodiments, the frequency of the voltage modulation wave signal and the current modulation wave signal are both 50 Hz or both 60 Hz. The frequency of the voltage modulation wave signal and the current modulation wave signal are mainly consistent with the frequency standard of the corresponding target power grid, for example, when the frequency standard of the target power grid is 50 Hz, the frequency of the voltage modulation wave signal and the current modulation wave signal correspond to 50 Hz, and the angular frequency of the voltage modulation wave signal and the current modulation wave signal ω = 100π; when the frequency standard of the target power grid is 60 Hz, the frequency of the voltage modulation wave signal and the current modulation wave signal correspond to 60 Hz, and the angular frequency of the voltage modulation wave signal and the current modulation wave signal ω = 120π.

[0087] In some embodiments, referring to FIG. 8, step S500 includes:

[0088] Step S501, fusing the waveform of the current modulation wave in the positive half cycle with the correction waveform to obtain the waveform of the corrected modulation wave signal in the positive half cycle;

[0089] Step S502, fusing the waveform of the current modulation wave in the negative half cycle with the correction waveform to obtain the waveform of the corrected modulation wave signal in the negative half cycle.

[0090] Specifically, taking 0-2π as an integer period for example, referring to FIG. 4, when the current modulation wave signal lags behind the voltage modulation wave signal, the waveform of the corrected modulation wave signal obtained by fusing the waveform of the current modulation wave in the positive half cycle with the correction waveform is that in the positive half cycle, no wave is emitted in the time period of 0 to φ, the waveform of the current modulation wave signal is emitted in the time period of φ to A, and the waveform of the voltage modulation wave signal is emitted in the time period of A to π; the waveform of the corrected modulation wave signal obtained by fusing the waveform of the current modulation wave in the negative half cycle with the correction waveform is that in the negative half cycle, no wave is emitted in the time period of π to π+φ, the waveform of the current modulation wave signal is emitted in the time period of π+φ to B, and the waveform of the voltage modulation wave signal is emitted in the time period of B to 2π.

[0091] Further, taking 0-2π as an integral period for example, referring to FIG. 6, when the current modulation wave signal is phase-advanced relative to the voltage modulation wave signal, the waveform of the current modulation wave in the positive half period is fused with the correction waveform, and the waveform of the corrected modulation wave signal obtained is that in the positive half period, in the time period of 0 to A, the waveform of the voltage modulation wave signal is emitted, in the time period of A to π-φ, the waveform of the current modulation wave signal is emitted, and in the time period of π-φ to π, no wave is emitted; the waveform of the current modulation wave in the negative half period is fused with the correction waveform, and the waveform of the corrected modulation wave signal obtained is that in the negative half period, in the time period of π to B, the waveform of the voltage modulation wave signal is emitted, in the time period of B to 2π-φ, the waveform of the current modulation wave signal is emitted, and in the time period of 2π-φ to 2π, no wave is emitted.

[0092] The application also provides an inverter controller, which stores a computer program executed by a processor to implement the control method of the flyback inverter grid-connected power factor as described above.

[0093] In some other embodiments, referring to FIG. 9, the method of the application is implemented by obtaining, by the inverter controller, the working signal of the target power grid; then the working signal is phase-locked by the phase-locked technology to obtain a voltage modulation wave signal consistent in phase and frequency with the working signal; the inverter controller calculates the power factor angle according to the phase and frequency of the voltage modulation wave signal and the preset power factor input by the user obtained by the inverter controller, thereby determining the phase of the current modulation wave signal, and taking the frequency of the voltage modulation wave signal as the frequency of the current modulation wave signal, thereby generating the current modulation wave signal; then the inverter controller generates the waveform of the corrected modulation wave signal according to the waveform of the voltage modulation wave signal, the waveform of the current modulation wave signal and the intersection of the two waveforms; wherein the waveform of the corrected modulation wave signal includes the first waveform of the current modulation wave in the first preset time period and the second waveform of the voltage modulation wave in the second preset time period; finally, the inverter controller inputs the generated waveform of the corrected modulation wave signal into the flyback inverter to control the flyback inverter to output the target alternating current corresponding to the waveform of the corrected modulation wave signal to the target power grid or the power consumption device.

[0094] Specifically, the controller is an inverter controller for controlling the flyback inverter. The controller includes a microprocessor, which is one of the core components of the controller, responsible for overall control and coordination functions. The microprocessor can implement the control algorithm and logic of the flyback inverter, including power regulation, frequency control, voltage adjustment, etc., to ensure that the output power of the flyback inverter meets the grid requirements. The microprocessor also provides a communication interface with external systems, such as a monitoring system, for example, a grid interface. Through the communication interface, the microprocessor can exchange data with external devices, receive instructions, and report the operating status of the flyback inverter through the monitoring system. In addition, the microprocessor can process data from various sensors (such as current sensors, voltage sensors) and input devices (such as buttons, switches), and make appropriate decisions based on the monitored conditions, such as switching operating modes or adjusting output parameters.

[0095] As an example of the controlled object, as shown in FIG. 10, the flyback inverter specifically includes a transformer T, switch tubes S0-S2, filter capacitors C1-C3, thyristors SCR1-SCR2, diodes D1, and inductors L1. In the circuit structure of FIG. 10, MOS or IGBT tubes are included but not limited to as flyback switch tubes on the primary side and secondary side of the transformer, respectively. When the grid absorbs power, the transformer primary side MOS tube S0 acts as a main switch to store energy in the transformer, and the transformer secondary side diode D1 acts as a secondary switch to rectify; when the grid sends out power, the transformer primary side MOS tube S0 acts as a secondary switch to rectify, and the transformer secondary side diode D1 acts as a main switch to store energy in the transformer. The circuit structure in FIG. 10 also includes a photovoltaic panel, which provides an input voltage for the inverter. The high-frequency flyback switch S0 is composed of MOS or IGBT tubes, S1 and S2 are output power frequency switch tubes, SCR1 and SCR2 are thyristors, S1 and SCR1 are connected in series, S2 and SCR2 are connected in series, S1 and SCR1 are connected in parallel with the series circuit of S2 and SCR2, forming a power frequency switch structure as shown in FIG. 10. The output power frequency switch tubes are composed of MOS or IGBT tubes, and the controller is connected to the grid and the input end of the flyback inverter. It should be noted that the circuit diagram described in the present application is for illustration only, and the present application does not limit the specific structure of the circuit diagram.

[0096] To sum up, the application firstly acquires a voltage modulation wave signal according to a working signal of a target power grid, then obtains a current modulation wave signal by phase shifting according to the voltage modulation wave signal and a preset power factor, uses part of the waveform of the voltage modulation wave signal as a correction waveform of the current modulation wave signal and fuses the waveform of the current modulation wave signal to obtain a waveform of a corrected modulation wave signal, and inputs the generated corrected modulation wave signal into a flyback inverter, so that the power factor can be accurately adjusted when the flyback inverter is connected to the grid, the harmonics can be reduced, the power efficiency and power quality of the power supply system are improved, and the economic and safe operation of the power grid and electrical equipment is ensured.

[0097] The above only describes some or preferred embodiments of the application, and neither the text nor the drawings can limit the scope of protection of the application. Any equivalent structural transformation using the content of the specification and drawings, or direct / indirect application in other related technical fields is included in the scope of protection of the application.

Claims

1. A control method of a flyback inverter grid-connected power factor, characterized in that, The method comprises the following steps: acquiring an operating signal of a target power grid; phase-locked the operating signal to obtain a voltage modulation wave signal consistent with the phase and frequency of the operating signal; phase-shifting the voltage modulation wave signal according to a power factor angle corresponding to a preset power factor to obtain a current modulation wave signal consistent with the frequency of the voltage modulation wave signal and having a phase angle difference relative to the voltage modulation wave signal; the waveforms of the voltage modulation wave signal and the current modulation wave signal are both sinusoidal modulation waveforms; acquiring the waveforms of the voltage modulation wave signal and the current modulation wave signal and the intersection of the two waveforms, selecting a partial waveform of the voltage modulation wave signal as a corrected waveform of the current modulation wave signal in a corresponding time period; fusing the corrected waveform and a partial waveform of the current modulation wave signal to obtain a corrected modulation wave signal waveform; controlling a flyback inverter to output target alternating current corresponding to the corrected modulation wave signal waveform to the target power grid or a power consumption device.

2. The control method of the flyback inverter grid-connected power factor according to claim 1, characterized in that, The phase-shifting the voltage modulation wave signal according to a power factor angle corresponding to a preset power factor to obtain a current modulation wave signal consistent with the frequency of the voltage modulation wave signal and having a phase angle difference relative to the voltage modulation wave signal comprises: calculating a phase difference angle of the current modulation wave signal relative to the voltage modulation wave signal according to a power factor angle corresponding to a preset power factor; operating the phase of the voltage modulation wave signal with the phase difference angle to obtain the phase of the current modulation wave signal; phase-shifting the voltage modulation wave signal according to the phase of the current modulation wave signal to obtain the current modulation wave signal.

3. The control method of the flyback inverter grid-connected power factor according to claim 2, characterized in that, The phase-shifting the voltage modulation wave signal according to a power factor angle corresponding to a preset power factor to obtain a current modulation wave signal consistent with the frequency of the voltage modulation wave signal and having a phase angle difference relative to the voltage modulation wave signal comprises: when the load connected with the flyback inverter is an inductive load, phase-shifting the voltage modulation wave signal in a lag direction according to a power factor angle corresponding to a preset power factor; or when the load connected with the flyback inverter is a capacitive load, phase-shifting the voltage modulation wave signal in a lead direction according to a power factor angle corresponding to a preset power factor.

4. The control method of the flyback inverter grid-connected power factor according to claim 3, characterized in that, The acquiring the waveforms of the voltage modulation wave signal and the current modulation wave signal and the intersection of the two waveforms, selecting a partial waveform of the voltage modulation wave signal as a corrected waveform of the current modulation wave signal in a corresponding time period comprises: when the phase of the current modulation wave signal lags behind the phase of the voltage modulation wave signal, acquiring the intersection of the waveform of the current modulation wave signal and the waveform of the voltage modulation wave signal in a half cycle, and taking the waveform of the voltage modulation wave signal from the intersection to the zero-crossing point of the voltage modulation wave signal as the corrected waveform of the current modulation wave signal; when the phase of the current modulation wave signal leads the phase of the voltage modulation wave signal, acquiring the intersection of the waveform of the voltage modulation wave signal and the waveform of the current modulation wave signal in a half cycle, and taking the waveform from the zero-crossing point of the voltage wave signal to the intersection as the corrected waveform of the current modulation wave signal.

5. The control method of the flyback inverter grid-connected power factor according to claim 1, characterized in that, The fusing of the modified waveform with the partial waveform of the current modulation wave signal comprises: obtaining the intersection points of the waveform of the current modulation wave signal and the waveform of the voltage modulation wave signal in the positive half cycle and the negative half cycle; when the current modulation wave signal lags behind the voltage modulation wave signal in phase, selecting the time period from the intersection point in the positive half cycle to the end point of the positive half cycle and the time period from the intersection point in the negative half cycle to the end point of the negative half cycle of the current modulation wave signal and the logical low level to perform logical and operation to obtain a first waveform signal; selecting the time period from the start point of the positive half cycle to the intersection point in the positive half cycle and the time period from the start point of the negative half cycle to the intersection point in the negative half cycle of the voltage modulation wave signal and the logical low level to perform logical and operation to obtain a second waveform signal; and generating the waveform of the modified modulation wave signal according to the first waveform signal and the second waveform signal; when the current modulation wave signal leads the voltage modulation wave signal in phase, selecting the time period from the start point of the positive half cycle to the intersection point in the positive half cycle and the time period from the start point of the negative half cycle to the intersection point in the negative half cycle of the current modulation wave signal and the logical low level to perform logical and operation to obtain a first waveform signal; selecting the time period from the intersection point in the positive half cycle to the end point of the positive half cycle and the time period from the intersection point in the negative half cycle to the end point of the negative half cycle of the voltage modulation wave signal and the logical low level to perform logical and operation to obtain a second waveform signal; and generating the waveform of the modified modulation wave signal according to the first waveform signal and the second waveform signal.

6. The control method of the flyback inverter grid-connected power factor according to claim 5, characterized in that, The generating of the waveform of the modified modulation wave signal according to the first waveform signal and the second waveform signal comprises: performing logical or operation on the first waveform signal and the second waveform signal to obtain the modified modulation wave signal.

7. The control method of the flyback inverter grid-connected power factor according to claim 1, characterized in that, The method further comprises, after the step of fusing the modified waveform with the partial waveform of the current modulation wave signal to obtain the waveform of the modified modulation wave signal: obtaining the waveform of the sine modulation wave signal according to the waveform of the voltage modulation wave signal and the waveform of the current modulation wave signal, wherein the frequency and the phase of the sine modulation wave signal are consistent with the frequency and the phase of the modified modulation wave signal respectively; obtaining a carrier signal, the carrier signal being a triangular wave signal or a sawtooth wave signal; superimposing the sine modulation wave signal and the carrier signal to obtain the modified modulation wave signal.

8. The control method of the flyback inverter grid-connected power factor according to claim 1, characterized in that, The fusing of the modified waveform with the partial waveform of the current modulation wave signal comprises: fusing the waveform of the current modulation wave in the positive half cycle with the modified waveform to obtain the waveform of the modified modulation wave signal in the positive half cycle; fusing the waveform of the current modulation wave in the negative half cycle with the modified waveform to obtain the waveform of the modified modulation wave signal in the negative half cycle.

9. The control method of the flyback inverter grid-connected power factor according to any one of claims 1 to 8, characterized in that, The frequency of the working electrical signal is 50 Hz or 60 Hz.

10. An inverter controller characterized by comprising: The inverter controller stores a computer program, and the computer program is executed by a processor to implement the control method of the flyback inverter grid-connected power factor. The inverter controller stores a computer program, and the computer program is executed by a processor to implement the control method of the flyback inverter grid-connected power factor.

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