Dual-current-based control method for grid-connected power factor of flyback inverter, and controller

Abstract

The present application discloses a dual-current-based control method for a grid-connected power factor of a flyback inverter, and a controller. The method comprises: acquiring an working electrical signal of a target power grid; obtaining a first current modulation wave signal; obtaining a second current modulation wave signal; obtaining a waveform of a corrected modulation wave signal; and controlling a flyback inverter to output, to the target power grid or an electric device, a target alternating current corresponding to the waveform of the corrected modulation wave signal. The corrected modulation wave signal, which is generated by using a second half waveform of the first current modulation wave signal and a first half waveform of the second current modulation wave signal, has a signal having a phase and frequency consistent with those of the working electrical signal of the power grid, and also has a signal having a phase angle difference from the working electrical signal of the power grid. By using the corrected modulation wave signal of the present application to control the flyback inverter, the flyback inverter can accurately adjust the power factor during grid connection and the harmonic distortion rate is reduced.

Description

Method and controller for grid-connected power factor of dual-current control flyback inverter TECHNICAL FIELD

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

[0002] In recent years, with the increasing energy crisis and environmental problems, solar energy as a clean and renewable energy has developed rapidly. Photovoltaic power generation based on renewable solar energy 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 SPWM technology, the inverter simulates a sine waveform by rapidly switching switching devices (such as IGBTs). 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 photovoltaic power generation circuit generally has inductive or capacitive load, thereby generating active power and reactive power, which are out of sync or have a phase angle, resulting in a change 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 prior art.

[0005] SUMMARY

[0006] The main purpose of the present application is to provide a method and controller for grid-connected power factor of dual-current control flyback inverter, aiming to solve the problem of how to accurately adjust the power factor.

[0007] To achieve the above purpose, the present application provides a method for grid-connected power factor of dual-current control flyback inverter, comprising the following steps:

[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 and a first current modulation wave signal consistent with the phase and frequency of the working electrical signal;

[0010] The first current modulation wave signal is phase-shifted according to a phase angle corresponding to a preset power factor, to obtain a second current modulation wave signal which has a same frequency as the first current modulation wave signal and has a phase angle difference with respect to the first current modulation wave signal;

[0011] Waveforms of the first current modulation wave signal and the second current modulation wave signal are obtained, partial waveforms of the first current modulation wave signal and the second current modulation wave signal are selected respectively, and the two waveforms are fused to obtain a waveform of a corrected modulation wave signal;

[0012] The flyback inverter is controlled to output target alternating current corresponding to the waveform of the corrected modulation wave signal to a target power grid or a target electrical device.

[0013] In some embodiments, the fusing of the corrected waveform and the partial waveform of the current modulation wave signal to obtain the waveform of the corrected modulation wave signal comprises:

[0014] An intersection of the waveform of the first current modulation wave signal and the waveform of the second current modulation wave signal in each half cycle is obtained;

[0015] The waveform of the first current modulation wave signal on one side of the intersection is taken as a first half waveform, and the waveform of the second current modulation wave signal on the other side of the intersection is taken as a second half waveform;

[0016] The first half waveform and the second half waveform are spliced to obtain the waveform of the corrected modulation wave signal.

[0017] In some embodiments, the fusing of the corrected waveform and the partial waveform of the current modulation wave signal to obtain the waveform of the corrected modulation wave signal comprises:

[0018] When the first current modulation wave signal leads the second current modulation wave signal, the waveform of the second current modulation wave signal corresponding to a zero point of the second current modulation wave signal to the intersection is selected as the first half waveform, and the waveform of the first current modulation wave signal corresponding to the intersection to an end point of the half cycle in each half cycle is selected as the second half waveform;

[0019] When the first current modulation wave signal lags behind the second current modulation wave signal, the waveform of the second current modulation wave signal corresponding to the intersection to a zero point of the second current modulation wave signal in each half cycle is selected as the first half waveform, and the waveform of the first current modulation wave signal corresponding to a start point of the half cycle to the intersection in each half cycle is selected as the second half waveform.

[0020] In some embodiments, the phase angle corresponding to the preset power factor is used to phase shift the first current modulation wave signal to obtain a second current modulation wave signal having the same frequency as the first current modulation wave signal and a phase angle difference with respect to the first current modulation wave signal, and the second current modulation wave signal is obtained by:

[0021] When the load connected to the flyback inverter is an inductive load, the first current modulation wave signal is phase shifted in a lagging direction according to the power factor angle corresponding to the preset power factor; or,

[0022] When the load connected to the flyback inverter is a capacitive load, the first current modulation wave signal is phase shifted in a leading direction according to the power factor angle corresponding to the preset power factor.

[0023] In some embodiments, the phase angle corresponding to the preset power factor is used to phase shift the first current modulation wave signal to obtain a second current modulation wave signal having the same frequency as the first current modulation wave signal and a phase angle difference with respect to the first current modulation wave signal, and the second current modulation wave signal is obtained by:

[0024] The phase difference angle of the second current modulation wave signal with respect to the first current modulation wave is calculated according to the power factor angle corresponding to the preset power factor;

[0025] The phase of the first current modulation wave is operated with the phase difference angle to obtain the phase of the second current modulation wave signal;

[0026] The frequency of the first current modulation wave signal is used as the frequency of the current modulation wave signal, and the second current modulation wave signal is obtained according to the phase of the second current modulation wave signal.

[0027] In some embodiments, the two waveforms are fused to obtain the waveform of the modified modulation wave signal, including:

[0028] The two waveforms are fused to obtain the waveform of the sinusoidal modulation wave signal;

[0029] The carrier signal is obtained, and the carrier signal is a triangular wave signal or a sawtooth wave signal;

[0030] The sinusoidal modulation wave signal and the carrier signal are superimposed to obtain the modified modulation wave signal.

[0031] In some embodiments, the two waveforms are fused to obtain the waveform of the modified modulation wave signal, including:

[0032] The waveform of the modified modulation wave signal in the positive half cycle and the waveform of the modified modulation wave signal in the negative half cycle are obtained to obtain the waveform of the modified modulation wave signal in one period.

[0033] In some embodiments, the acquiring the waveforms of the first current modulation wave signal and the second current modulation wave signal, respectively selecting partial waveforms of the first current modulation wave signal and the second current modulation wave signal, and fusing the two waveforms to obtain the waveform of the corrected modulation wave signal include:

[0034] When the first current modulation wave signal leads the second current modulation wave signal, the first half waveform is obtained by performing logical AND operation on the time period of the first current modulation wave signal from the positive half cycle starting point to the intersection point, the time period of the first current modulation wave signal from the negative half cycle starting point to the intersection point, and the logical low level; the second half waveform is obtained by performing logical AND operation on the time period of the second current modulation wave signal from the intersection point to the positive half cycle ending point, the time period of the second current modulation wave signal from the intersection point to the negative half cycle ending point, and the logical low level; or,

[0035] When the first current modulation wave signal lags behind the second current modulation wave signal, the first half waveform is obtained by performing logical AND operation on the time period of the second current modulation wave signal from the positive half cycle starting point to the intersection point, the time period of the second current modulation wave signal from the negative half cycle starting point to the intersection point, and the logical low level; the second half waveform is obtained by performing logical AND operation on the time period of the first current modulation wave signal from the intersection point to the positive half cycle ending point, the time period of the first current modulation wave signal from the intersection point to the negative half cycle ending point, and the logical low level.

[0036] In some embodiments, the generating the corrected modulation wave signal according to the first current modulation wave signal and the second current modulation wave signal further includes:

[0037] Performing logical OR operation on the first half waveform and the second half waveform to obtain the corrected modulation wave signal.

[0038] The application also provides an inverter controller, which stores a computer program, and the computer program is executed by a processor to implement the method for double-current control flyback inverter grid-connected power factor according to any one of the above technical solutions.

[0039] The application generates the corrected modulation wave signal through the first half waveform of the second current modulation wave signal and the second half waveform of the first current modulation wave signal, and the corrected modulation wave signal has a signal consistent with the phase and frequency of the working signal of the grid and a signal having a phase angle difference with the working signal of the grid. Through the corrected modulation wave signal in the application, the flyback inverter can accurately adjust the power factor when connected to the grid, and the harmonic distortion rate is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0040] FIG. 1 is a step schematic diagram of a method for double-current control flyback inverter grid-connected power factor provided by an embodiment of the application;

[0041] Fig. 2 is a waveform diagram of u1, i1 and i2 when i2 lags u1 according to an embodiment of the present application;

[0042] Fig. 3 is a timing diagram of the waveform diagram of u1 and the modified modulation wave signal and the SPWM waveform diagram of the modified modulation wave signal when i2 lags u1 according to an embodiment of the present application;

[0043] Fig. 4 is a waveform diagram of u1, i1 and i2 when i2 leads u1 according to an embodiment of the present application;

[0044] Fig. 5 is a timing diagram of the waveform diagram of u1 and the modified modulation wave signal and the SPWM waveform diagram of the modified modulation wave signal when i2 leads u1 according to an embodiment of the present application;

[0045] Fig. 6 is a flowchart according to an embodiment of the present application;

[0046] Fig. 7 is a circuit diagram according to an embodiment of the present application.

[0047] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0048] The schemes in the embodiments of the present application will be described in a clear and complete manner with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0049] In addition, the description of "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the following steps. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0050] As shown in Fig. 1, the present application provides a method for double current control flyback inverter grid-connected power factor, which includes the following steps (S1, S2, S3, S4 and S5):

[0051] Step S1: obtaining a working electrical signal of a target power grid. The power grid in the present application refers to a system composed of power plants, power transmission lines, substations and power distribution facilities and other power devices. In the power grid, power transmission is carried out in an alternating current mode. The current and voltage in the power grid are sinusoidal alternating current, and the frequency is 50Hz or 60Hz. Therefore, the working electrical signal obtained by the present application is a sinusoidal alternating current signal with a frequency of 50Hz or 60Hz.

[0052] Step S2: phase locking the working electrical signal to obtain a voltage modulation wave signal u1 and a first current modulation wave signal i1 consistent with the phase and frequency of the working electrical signal. Specifically, phase locking the working electrical signal refers to obtaining a voltage modulation wave signal u1 and a first current modulation wave signal i1 consistent with the phase and frequency of the working electrical signal through phase locking technology. It should be noted that the working electrical signal is a voltage signal. Phase locking technology is a technology that controls the phase of a controlled oscillator with a standard signal or an external signal, which is used to achieve phase synchronization with an external signal or track the frequency or phase of an external signal.

[0053] Step S3: obtaining a second current modulation wave signal i2 consistent with the frequency of the first current modulation wave signal i1 and having a phase angle difference with respect to the first current modulation wave signal i1 according to a preset power factor and the first current modulation wave signal i1. The correction modulation wave signal includes a first half waveform and a second half waveform. The first half waveform is the waveform signal of the second current modulation wave signal i2 in the first preset time period or the second preset time period. The second half waveform is the waveform signal of the first current modulation wave signal i1 in the third preset time period or the fourth preset time period. It should be noted that the phase angle difference is the difference between the initial phase of the second current modulation wave signal i2 and the initial phase of the first current modulation wave signal i1. As an embodiment, after obtaining the preset power factor, the power factor angle is obtained by the power factor. The power factor angle is the phase angle difference. The first current modulation wave signal i1 leads or lags the second current modulation wave signal i2. As an embodiment, the second current modulation wave signal i2 lags the first current i1 by Ψ. Specifically, the preset power factor angle is the power factor angle required by the power grid. As an embodiment, the working electrical signal is a sinusoidal alternating voltage signal with a frequency of 50Hz, the preset power factor angle is Ψ, and the preset power factor is cosΨ.

[0054] In some embodiments, step S3 comprises: phase-shifting the first current modulation wave signal according to the phase angle corresponding to the preset power factor to obtain a second current modulation wave signal i2 which is consistent with the frequency of the first current modulation wave signal i1 and has a phase angle difference with respect to the first current modulation wave signal i1. Specifically, when the load connected to the flyback inverter is an inductive load, the first current modulation wave signal i1 is phase-shifted in a lagging direction according to the phase angle corresponding to the preset power factor to obtain the second current modulation wave signal i2 which is consistent with the frequency of the first current modulation wave signal i1 and has a phase angle difference with respect to the first current modulation wave signal i1; when the load connected to the flyback inverter is a capacitive load, the first current modulation wave signal i1 is phase-shifted in an advancing direction according to the phase angle corresponding to the preset power factor to obtain the second current modulation wave signal i2 which is consistent with the frequency of the first current modulation wave signal i1 and has a phase angle difference with respect to the first current modulation wave signal i1.

[0055] Step S4: obtaining waveforms of the first current modulation wave signal i1 and the second current modulation wave signal i2, respectively selecting partial waveforms of the first current modulation wave signal i1 and the second current modulation wave i2, and fusing the two waveforms to obtain a waveform of a corrected modulation wave signal. The corrected modulation wave signal comprises a first half waveform and a second half waveform connected to each other, the first half waveform is a waveform signal of the second current modulation wave signal i2 in a first preset time period, and the second half waveform is a waveform signal of the first current modulation wave signal i1 in a second preset time period. Since the corrected modulation wave is generated according to the first current modulation wave signal i1 and the second current modulation wave signal i2, the flyback inverter is controlled by the corrected modulation wave signal, which is called double current control.

[0056] As an implementation manner, the first current modulation wave signal i1 and the second current modulation wave signal i2 are both sinusoidal pulse width modulation (SPWM) wave signals, which are output signals approximating sinusoidal waves. SPWM adjusts the width of square wave pulses so that the average value changes to a sinusoidal waveform in a cycle, thereby realizing control of alternating voltage and current. SPWM wave signals have the characteristics of low harmonic content, flexible control and high efficiency. In some embodiments, the corrected modulation wave signal is a sinusoidal pulse width modulation wave signal. Specifically, as shown in FIG. 3 and FIG. 5, FIG. 3 has a SPWM waveform diagram of a sinusoidal corrected modulation wave when the second sinusoidal modulation wave signal lags behind the operating electric signal, and FIG. 5 has a SPWM waveform diagram of a sinusoidal corrected modulation wave when the second sinusoidal modulation wave signal advances the operating electric signal.

[0057] As an implementation manner, either of the first current modulation wave signal i1 and the second current modulation wave signal i2 is a SPWM wave signal.

[0058] Step S5: controlling the flyback inverter to output target AC power corresponding to the waveform of the modified modulation wave signal to the target power grid or the power utilization device. It should be noted that the flyback inverter in the present application refers to an inverter using flyback switching power supply technology. Flyback switching power supply refers to a switching power supply using a flyback high-frequency transformer to isolate the input and output circuits. 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 inverter in the 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.

[0059] In some embodiments, the first current modulation wave signal i1 and the second current modulation wave signal i2 have intersection points in each half cycle. Specifically, as shown in FIG. 2, the second current modulation wave signal i2 lags behind the first current modulation wave signal i1 by Ψ. The intersection point of the first current modulation wave signal i1 and the second current modulation wave signal i2 in the positive half cycle corresponds to point A, and the intersection point of the first current modulation wave signal i1 and the second current modulation wave signal i2 in the negative half cycle corresponds to point B. The first preset time period is the time period from the zero point of the value of the second current modulation wave signal i2 (for example, points Ψ and π+Ψ in FIGS. 2 and 3) to the intersection point in each half cycle of the second current modulation wave signal i2, that is, the time period from point Ψ to point A and the time period from point π+Ψ to point B in FIGS. 2 and 3 are both the first preset time period. The third preset time period is the time period from the intersection point to the end point of the half cycle (for example, points π and 2π in FIGS. 2 and 3) in each half cycle of the first current modulation wave signal i1, that is, the time period from point A to the end point of the positive half cycle (π) and the time period from point B to the end point of the negative half cycle (2π) in FIG. 2 are both the third preset time period.

[0060] In some embodiments, as shown in FIGS. 2 and 3, the first half waveform is obtained by performing logical AND operation on the first current modulation wave signal i1 and the logical low level in the time period from the start point of the positive half cycle (for example, point 0 in FIG. 2) to point A and the time period from the start point of the negative half cycle (π) to point B. Preferably, the logical low level for performing logical AND operation with the first current modulation wave signal i1 is the logical low level in the half cycle of the first current modulation wave signal i1.

[0061] In some embodiments, as shown in FIG. 2 and FIG. 3, the second half waveform is obtained by performing logical AND operation between the second current modulation wave signal i2 and the logical low level in the time period from point A to the end point of the positive half cycle (π+Ψ) and the time period from point B to the end point of the negative half cycle (2π+Ψ). Then, the first half waveform and the second half waveform are subjected to logical OR operation to obtain the modified modulation wave signal. Preferably, the logical low level subjected to the logical AND operation with the second current modulation wave signal i2 is the logical low level in the half cycle of the second current modulation wave signal i2.

[0062] As an implementation, as shown in FIG. 4 and FIG. 5, the second current modulation wave signal i2 is ahead of the first current modulation wave signal i1 by Ψ. The fourth preset time period is the time period corresponding to the intersection point to the start point of the half cycle (e.g. 0 point and π point in FIG. 4 and FIG. 5) of the first current modulation wave signal i1 in each half cycle, i.e. the time period from 0 point to A point and the time period from π point to B point in FIG. 4 and FIG. 5. The second preset time period is the time period corresponding to the intersection point to the zero point of the value of the second current modulation wave signal i2 (e.g. π-Ψ point and 2π-Ψ point in FIG. 4 and FIG. 5) in each half cycle of the second current modulation wave signal i2, i.e. the time period from A point to the end point of the positive half cycle (π-Ψ) and the time period from B point to the end point of the negative half cycle (2π-Ψ) in FIG. 4 and FIG. 5.

[0063] In some embodiments, as shown in FIG. 4 and FIG. 5, when the second current modulation wave signal i2 is ahead of the first current modulation wave signal i1 by Ψ, the first half waveform is obtained by performing logical AND operation between the second current modulation wave signal i2 and the logical low level in the time period from the start point of the positive half cycle (e.g. -Ψ point in FIG. 4 and FIG. 5) to A point and the time period from the start point of the negative half cycle (e.g. π point in FIG. 4 and FIG. 5) to B point. Preferably, the logical low level subjected to the logical AND operation with the second current modulation wave signal i2 is the logical low level in the half cycle of the second current modulation wave signal i2.

[0064] In some embodiments, as shown in FIG. 4 and FIG. 5, the second half waveform is obtained by performing logical AND operation between the first current modulation wave signal i1 and the logical low level in the time period from A point to the end point of the positive half cycle (e.g. π point in FIG. 4 and FIG. 5) and the time period from B point to the end point of the negative half cycle (e.g. 2π point in FIG. 4 and FIG. 5). Then, the first half waveform and the second half waveform are subjected to logical OR operation to obtain the modified modulation wave signal. Preferably, the logical low level subjected to the logical AND operation with the first current modulation wave signal i1 is the logical low level in the half cycle of the first current modulation wave signal i1.

[0065] In some embodiments, the control of the flyback inverter to output the target AC power corresponding to the modified modulation wave signal to the target power grid or the target electrical device comprises the following steps:

[0066] The switch tube in the flyback inverter is controlled by the modified modulation wave signal, so that the power supply outputs the target AC power corresponding to the modified modulation wave signal to the target power grid or the target electrical device through the flyback inverter.

[0067] In some embodiments, the first current modulation wave signal i1 and the second current modulation wave signal i2 have the same frequency. The first current modulation wave signal i1 and / or the second current modulation wave signal i2 are generated by a high-frequency carrier, preferably a sawtooth wave or a triangular wave.

[0068] As an embodiment, as shown in FIG. 6, the working signal of the target power grid is obtained by the controller. Specifically, the controller is an inverter controller for controlling the flyback inverter, and the controller includes a microprocessor, which is one of the core components of the controller and is 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 requirements of the power grid. The microprocessor also provides a communication interface with external systems, such as a monitoring system, and a power 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 and voltage sensors) and input devices (such as buttons and switches), and make appropriate decisions based on the monitored conditions, such as switching operating modes or adjusting output parameters.

[0069] In some embodiments, after the controller acquires the working signal of the target power grid, the working signal is phase-locked to obtain a first current modulation wave signal i1 consistent with the initial phase and frequency of the working signal by a phase-locked loop technique. Meanwhile, the controller can acquire a preset power factor of the power supply to be connected to the grid. It should be noted that, assuming that the power factor of the power grid is 1, the preset power factor can be set to 0.8 or 0.9 according to the nature of the load in the power supply to be connected to the grid (for example, an inductive load or a capacitive load). After acquiring the preset power factor, the controller obtains a second current modulation wave signal i2 consistent with the frequency of the first current modulation wave signal i1 and having a phase angle difference with respect to the first current modulation wave signal i1 according to the preset power factor and the first current modulation wave signal i1. Specifically, the second current modulation wave signal i2 is obtained by phase-shifting the first current modulation wave signal i1, and the phase-shifting angle is the angle corresponding to the preset power factor, i.e., the phase angle difference. When the load is an inductive load, the second current modulation wave signal i2 is obtained by phase-shifting the first current modulation wave signal i1 in the lag direction; when the load is a capacitive load, the second current modulation wave signal i2 is obtained by phase-shifting the first current modulation wave signal i1 in the lead direction. The controller obtains a time difference corresponding to the phase angle difference according to the phase angle difference. Then the controller generates a corrected modulation wave signal according to the time difference and the first current modulation wave signal i1, wherein the half-cycle time length of the corrected modulation wave signal is equal to the difference between the half-cycle time length of the first current modulation wave signal i1 and the time difference. It can be seen that the period and frequency of the corrected modulation wave signal are thus generated, and the corrected modulation wave signal is generated. Finally, the controller controls the flyback inverter to output target alternating current corresponding to the corrected modulation wave signal to the target power grid or the power device based on the corrected modulation wave signal.

[0070] As an implementation, phase-shifting the first current modulation wave signal according to the phase angle corresponding to the preset power factor to obtain a second current modulation wave signal consistent with the frequency of the first current modulation wave signal and having a phase angle difference with respect to the first current modulation wave signal includes:

[0071] calculating the phase difference angle of the second current modulation wave signal with respect to the first current modulation wave signal according to the power factor angle corresponding to the preset power factor;

[0072] operating the phase of the first current modulation wave with the phase difference angle to obtain the phase of the second current modulation wave signal;

[0073] taking the frequency of the first current modulation wave signal as the frequency of the current modulation wave signal, and obtaining the second current modulation wave signal according to the phase of the second current modulation wave signal.

[0074] In some embodiments, the controller generates a modified modulation wave signal according to the first current modulation wave signal i1 and the second current modulation wave signal i2, wherein the modified modulation wave signal comprises a first half waveform and a second half waveform, the first half waveform is a waveform signal of the second current modulation wave signal i2 in a first preset time period, and the second half waveform is a waveform signal of the first current modulation wave signal i1 in a second preset time period. Finally, the controller controls the flyback inverter to output target alternating current corresponding to the modified modulation wave signal to the target power grid or the target electrical equipment based on the modified modulation wave signal.

[0075] As an implementation, as shown in FIG. 7, the flyback inverter specifically comprises a transformer T, switch tubes S0-S2, filter capacitors C1-C3, thyristors SCR1-SCR2, diodes D1, and an inductor L1. In the circuit structure of FIG. 7, MOS tubes or IGBT tubes are arranged as flyback switch tubes on the primary side and the secondary side of the transformer, respectively, and when the power grid absorbs power, the MOS tube S0 on the primary side of the transformer serves as a main switch to store power in the transformer, and the diode D1 on the secondary side of the transformer serves as an auxiliary switch to rectify; when the power grid sends out power, the MOS tube S0 on the primary side of the transformer serves as an auxiliary switch to rectify, and the diode D1 on the secondary side of the transformer serves as a main switch to store power in the transformer. The circuit structure of FIG. 7 further comprises a photovoltaic panel, which provides an input voltage of the inverter, the high-frequency flyback switch S0 is composed of MOS tubes 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 connection of S2 and SCR2, thereby forming a power-frequency switch structure as shown in FIG. 7, the output power-frequency switch tubes are composed of MOS tubes or IGBT tubes, and a controller is connected to the input end of the power grid and the flyback inverter. It should be noted that the circuit diagram described in the present application is for illustration only, and the specific structure of the circuit diagram is not limited in the present application.

[0076] The present application also provides an inverter controller, which stores a computer program executed by a processor to implement the method for double-current control flyback inverter grid-connected power factor according to any one of the above technical solutions.

[0077] The technical scheme of the present application has the advantages that: the first half waveform of the second current modulation wave signal and the second half waveform of the first current modulation wave signal generate a modified modulation wave signal having a signal consistent with the phase and frequency of the working signal of the power grid and a signal having a phase angle difference with the working signal of the power grid. The flyback inverter is controlled by the modified modulation wave signal in the present application, so that the flyback inverter can accurately adjust the power factor during grid connection, and the harmonic distortion rate is reduced.

[0078] The above merely provides part or preferred embodiments of the present application, and neither the text nor the drawings can limit the scope of protection of the present application. Any equivalent structure transformation made with the content of the present application and the drawings, or direct / indirect application in other related technical fields under the concept of the present application as a whole are included in the scope of protection of the present application.

Claims

1. A method for double current control flyback inverter grid-connected power factor, characterized in that, The method comprises the following steps: obtaining an operating signal of a target power grid; phase-locked the operating signal to obtain a voltage modulation wave signal and a first current modulation wave signal consistent with the phase and frequency of the operating signal; phase-shifting the first current modulation wave signal according to a phase angle corresponding to a preset power factor to obtain a second current modulation wave signal consistent with the frequency of the first current modulation wave signal and having a phase angle difference with respect to the first current modulation wave signal; obtaining waveforms of the first current modulation wave signal and the second current modulation wave signal, selecting partial waveforms of the first current modulation wave signal and the second current modulation wave respectively, and fusing the two waveforms to obtain a waveform of a corrected modulation wave signal; controlling the flyback inverter to output target alternating current corresponding to the waveform of the corrected modulation wave signal to the target power grid or a power consuming device.

2. The method of claim 1, wherein, The step of obtaining waveforms of the first current modulation wave signal and the second current modulation wave signal, selecting partial waveforms of the first current modulation wave signal and the second current modulation wave respectively, and fusing the two waveforms to obtain a waveform of a corrected modulation wave signal comprises: obtaining an intersection point of the waveform of the first current modulation wave signal and the waveform of the second current modulation wave signal in each half cycle; taking the waveform of the first current modulation wave signal on one side of the intersection point as a first half waveform and taking the waveform of the second current modulation wave signal on the other side of the intersection point as a second half waveform; splicing the first half waveform and the second half waveform to obtain the waveform of the corrected modulation wave signal.

3. The method of claim 2, wherein, The step of obtaining waveforms of the first current modulation wave signal and the second current modulation wave signal, selecting partial waveforms of the first current modulation wave signal and the second current modulation wave respectively, and fusing the two waveforms to obtain a waveform of a corrected modulation wave signal comprises: when the first current modulation wave signal leads the second current modulation wave, selecting a waveform of the second current modulation wave signal corresponding to a zero point of the second current modulation wave signal to the intersection point as a first half waveform and selecting a waveform of the first current modulation wave signal corresponding to the intersection point to an end point of the half cycle as a second half waveform; when the first current modulation wave signal lags behind the second current modulation wave, selecting a waveform of the second current modulation wave signal corresponding to the intersection point to a zero point of the second current modulation wave signal as a first half waveform and selecting a waveform of the first current modulation wave signal corresponding to a start point of the half cycle to the intersection point as a second half waveform.

4. The method of claim 1, wherein, The step of phase-shifting the first current modulation wave signal according to a phase angle corresponding to a preset power factor to obtain a second current modulation wave signal consistent with the frequency of the first current modulation wave signal and having a phase angle difference with respect to the first current modulation wave signal comprises: when a load connected to the flyback inverter is an inductive load, phase-shifting the first current modulation wave signal in a lagging 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, the first current modulation wave signal is phase-shifted in a leading direction according to a power factor angle corresponding to a preset power factor.

5. The method of claim 1, wherein, The phase-shifting the first current modulation wave signal according to a phase angle corresponding to a preset power factor to obtain a second current modulation wave signal having a same frequency as the first current modulation wave signal and having a phase angle difference with respect to the first current modulation wave signal comprises: calculating a phase angle difference of the second current modulation wave signal with respect to the first current modulation wave according to a power factor angle corresponding to a preset power factor; operating the phase of the first current modulation wave with the phase angle difference to obtain the phase of the second current modulation wave signal; taking the frequency of the first current modulation wave signal as the frequency of the second current modulation wave signal and obtaining the second current modulation wave signal according to the phase of the second current modulation wave signal.

6. The method of dual current controlled flyback inverter grid- tied power factor according to claim 1, wherein, The fusing the two waveforms to obtain the waveform of the modified modulation wave signal comprises: fusing the two waveforms to obtain the waveform of a sine modulation wave signal; 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.

7. The method of dual current controlled flyback inverter grid- tied power factor according to claim 2, wherein, The fusing the two waveforms to obtain the waveform of the modified modulation wave signal comprises: obtaining the waveform of the modified modulation wave signal in a positive half cycle and the waveform of the modified modulation wave signal in a negative half cycle to obtain the waveform of the modified modulation wave signal in a cycle.

8. The method of dual current controlled flyback inverter grid- tied power factor according to claim 7, characterized in that, The obtaining the waveforms of the first current modulation wave signal and the second current modulation wave signal, respectively selecting partial waveforms of the first current modulation wave signal and the second current modulation wave, and fusing the two waveforms to obtain the waveform of the modified modulation wave signal comprises: when the first current modulation wave signal leads the second current modulation wave signal, selecting a time period of the first current modulation wave signal from a positive half cycle starting point to the intersection point and a time period of the first current modulation wave signal from a negative half cycle starting point to the intersection point and a logic low level to perform a logical "and" operation to obtain a first half waveform; selecting a time period of the second current modulation wave signal from the intersection point to a positive half cycle ending point and a time period of the second current modulation wave signal from the intersection point to a negative half cycle ending point and a logic low level to perform a logical "and" operation to obtain a second half waveform; or when the first current modulation wave signal lags the second current modulation wave signal, selecting a time period of the second current modulation wave signal from a positive half cycle starting point to the intersection point and a time period of the second current modulation wave signal from a negative half cycle starting point to the intersection point and a logic low level to perform a logical "and" operation to obtain a first half waveform; selecting a time period of the first current modulation wave signal from the intersection point to a positive half cycle ending point and a time period of the first current modulation wave signal from the intersection point to a negative half cycle ending point and a logic low level to perform a logical "and" operation to obtain a second half waveform.

9. The method of claim 8, wherein, The obtaining the waveforms of the first current modulation wave signal and the second current modulation wave signal, respectively selecting partial waveforms of the first current modulation wave signal and the second current modulation wave, and fusing the two waveforms to obtain the waveform of the modified modulation wave signal further comprises: The first half-wave and the second half-wave are subjected to a logical OR operation to obtain the modified modulation wave signal.

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 method for double-current control flyback inverter grid-connected power factor as claimed in any one of claims 1 to 9.

Images