Method and controller for controlling grid-connected power factor of flyback inverter

Abstract

The present invention discloses a method for controlling the grid-connected power factor of a flyback inverter, comprising: obtaining a sinusoidal pulse width modulation wave signal of a target power grid, and a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period; performing a logic AND operation on the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal; and controlling the flyback inverter to output a target alternating current corresponding to the waveform of the modified modulation wave signal to the target power grid or electrical equipment. The present invention performs a logic AND operation on the pulse wave signal and the sinusoidal pulse width modulation wave signal to obtain a modified modulation wave signal, and by inputting the generated modified modulation wave signal into the flyback inverter, accurate adjustment of the power factor when the flyback inverter is connected to the grid can be achieved, thereby improving the power efficiency and power quality of the power supply system and ensuring the economical and safe operation of the power grid and electrical equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter control, and in particular to a method and a controller for controlling a grid-connected power factor of a flyback inverter. Background Art

[0002] Photovoltaic power generation based on renewable solar energy can produce more electric energy, thereby meeting the growing demand for electricity. Photovoltaic power generation often requires an inverter to convert direct current into alternating current, and then connect the alternating current to the corresponding power grid.

[0003] An inverter is a device that converts direct current (DC) into alternating current (AC). General inverters use a technique called PWM (pulse width modulation) or SPWM (sinusoidal pulse width modulation) to generate AC power. In the process of using SPWM technology, the inverter simulates a sine waveform by quickly switching switching devices (such as IGBT). Since the switching instantaneous change 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. In addition, the generated AC power will generate active power and reactive power when connected to the grid. The active power and reactive power will be out of sync or have a phase angle, resulting in a decrease in the power factor.

[0004] In the prior art, a diode is usually used for the output of a flyback circuit. This circuit can achieve a grid-connected current with a power factor of 1. However, due to the unidirectional conduction characteristics of the diode, it is impossible to transmit energy from the grid to the photovoltaic side, and it is also impossible to adjust the power factor of the inverter grid-connected. Currently, there is no detailed publicly disclosed inverter grid-connected control method specifically for flyback micro power factor adjustment in the prior art. Summary of the invention

[0005] The main purpose of the present invention is to propose a method for controlling the grid-connected power factor of a flyback inverter and an inverter controller, aiming to solve the problem that there is no detailed disclosure in the prior art of an inverter grid-connected control method specifically for adjusting the flyback micro power factor.

[0006] To achieve the above object, the present invention provides a method for controlling the grid-connected power factor of a flyback inverter, the method comprising:

[0007] Acquire a sinusoidal pulse width modulation wave signal of the target power grid, and a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period;

[0008] Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain the waveform of the modified modulation wave signal;

[0009] The flyback inverter is controlled to output target alternating current corresponding to the waveform of the modified modulation wave signal to the target power grid or power-consuming equipment.

[0010] Preferably, the step of acquiring a sinusoidal pulse width modulation wave signal of a target power grid comprises:

[0011] Acquire a sine wave signal and a carrier signal of a target power grid; the carrier signal is a triangular wave signal or a sawtooth wave signal; the frequency of the sine wave signal is less than the frequency of the carrier signal;

[0012] The sinusoidal wave signal is compared with the carrier signal to obtain the sinusoidal pulse width modulation wave signal having the same frequency as the sinusoidal wave signal.

[0013] Preferably, the frequency and phase of the sinusoidal pulse width modulation wave signal and the pulse wave signal are consistent;

[0014] The step of performing a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain the waveform of the modified modulation wave signal comprises:

[0015] The frequency and phase of the modified modulation wave signal are kept consistent with those of the sinusoidal pulse width modulation wave signal, a logic AND operation is performed on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal, and the waveform of the sinusoidal pulse width modulation wave signal within a preset time period is cut off to obtain the waveform of the modified modulation wave signal.

[0016] Preferably, obtaining a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period includes:

[0017] Acquire the frequency of the sinusoidal pulse width modulation wave signal;

[0018] Calculating the duration of the preset time period according to the frequency of the sinusoidal pulse width modulation wave signal and the preset power factor;

[0019] The frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, and the pulse wave signal is obtained according to the length of the preset time period.

[0020] Preferably, the calculating the duration of the preset time period according to the frequency of the sinusoidal pulse width modulation wave signal and the preset power factor comprises:

[0021] Calculating the period of the sinusoidal pulse width modulation wave signal according to the frequency of the sinusoidal pulse width modulation wave signal;

[0022] The duration of the preset time period is calculated according to the power factor angle corresponding to the preset power factor and the period of the sinusoidal pulse width modulation wave signal.

[0023] Preferably, the step of using the frequency of the sinusoidal pulse width modulation wave signal as the frequency of the pulse wave signal and obtaining the pulse wave signal according to the duration of the preset time period comprises:

[0024] When the load connected to the flyback inverter is an inductive load, the frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, so as to obtain a pulse wave signal that is at a logic low level between the start point of the half cycle and the power factor angle corresponding to the preset power factor, and at a logic high level between the power factor angle corresponding to the preset power factor and the end point of the half cycle in each half cycle;

[0025] Alternatively, when the load connected to the flyback inverter is a capacitive load, the frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, and a pulse wave signal is obtained that is a logic high level between the starting point of the half cycle and the power factor angle corresponding to the preset power factor in each half cycle, and a logic low level between the power factor angle corresponding to the preset power factor and the end point of the half cycle.

[0026] Preferably, the step of performing a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal, and removing the waveform of the sinusoidal pulse width modulation wave signal within a preset time period to obtain the waveform of the modified modulation wave signal comprises:

[0027] A logic AND operation is performed on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal which is a logic low level in a preset time period and is consistent with the waveform of the sinusoidal pulse width modulation wave signal in a non-preset time period.

[0028] Preferably, the waveform of the sinusoidal pulse width modulation wave signal is subjected to a logic AND operation with the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal which is a logic low level in a preset time period and is consistent with the waveform of the sinusoidal pulse width modulation wave signal in a non-preset time period, including:

[0029] Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal at a logic low level to obtain a first waveform corresponding to the logic low level;

[0030] Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal at a logic high level to obtain a second waveform consistent with the waveform of the sinusoidal pulse width modulation wave signal;

[0031] A logical OR operation is performed on the first waveform and the second waveform to obtain the waveform of the modified modulated wave signal.

[0032] Preferably, the frequency of the sinusoidal pulse width modulation wave signal is 50 Hz or 60 Hz.

[0033] The present invention also provides an inverter controller, wherein the inverter controller stores a computer program, and the computer program is executed by a processor to implement the method for controlling the grid-connected power factor of a flyback inverter as described above.

[0034] The beneficial effect of the technical solution of the present invention is that the present invention obtains a corrected modulated wave signal by performing a logical AND operation on a pulse wave signal and a sinusoidal pulse width modulation wave signal. Since the pulse wave signal is at a logical low level within a preset time period, the corrected modulated wave signal obtained after performing a logical AND operation with the sinusoidal pulse width modulation wave signal can cut off the part of the current that cannot flow back, so that when the generated corrected modulated wave signal is input into the flyback inverter, the power factor can be accurately adjusted when the flyback inverter is connected to the grid, thereby improving the power efficiency and power quality of the power supply system and ensuring the economical and safe operation of the power grid and electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flow chart of a method for controlling the grid-connected power factor of a flyback inverter provided by an embodiment of the present invention;

[0036] Figure 2 A flow chart of obtaining a sinusoidal pulse width modulation wave signal of a target power grid according to an embodiment of the present invention;

[0037] Figure 3 The waveform diagram of u1 and i0 provided in the embodiment of the present invention;

[0038] Figure 4 A flow chart of obtaining a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period according to an embodiment of the present invention;

[0039] Figure 5 This is a flowchart of step S104 of an embodiment of the present invention;

[0040] Figure 6 A timing diagram of a waveform diagram of a modified modulation wave signal and an SPWM waveform diagram of a modified modulation wave signal when the power factor is lagging provided by an embodiment of the present invention;

[0041] Figure 7 A timing diagram of a waveform diagram of a corrected modulation wave signal when the power factor is leading and an SPWM waveform diagram of a corrected modulation wave signal provided by an embodiment of the present invention;

[0042] Figure 8 An information flow diagram for implementing a method for controlling a flyback inverter grid-connected power factor according to an embodiment of the present invention;

[0043] Fig. 9 A circuit diagram provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] In view of the technical defects in the related technologies of the existing flyback micro grid-connected power factor adjustment, the embodiment of the present invention proposes a method for controlling the grid-connected power factor of a flyback inverter, referring to Figure 1 , the method comprising:

[0046] Step S100, obtaining a sinusoidal pulse width modulated wave signal of a target power grid, and a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period; in some embodiments, the inverter controller can obtain a sinusoidal pulse width modulated wave signal (frequency is f1, period T1=1 / f1) of the target power grid from the target power grid, obtain the power factor input by the user from the user end as the preset power factor, and obtain the corresponding power factor angle φ according to the preset power factor (cosφ), then the duration of the preset time period t=(φ / π)*T1 / 2=φ / 2πf1.

[0047] Step S200, perform a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal; as an implementation mode, the inverter controller performs a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal that is a logic low level within a preset time period and is consistent with the waveform of the sinusoidal pulse width modulation wave signal within a non-preset time period.

[0048] Step S300: Control the flyback inverter to output target alternating current corresponding to the modified modulation wave signal waveform to the target power grid or power-consuming equipment.

[0049] In this embodiment, a corrected modulated wave signal is obtained by performing a logical AND operation on a pulse wave signal and a sinusoidal pulse width modulated wave signal. Since the pulse wave signal is at a logic low level within a preset time period, the corrected modulated wave signal obtained by performing a logical AND operation on the sinusoidal pulse width modulated wave signal can cut off the portion of the current that cannot flow back, thereby inputting the generated corrected modulated wave signal into the flyback inverter to accurately adjust the power factor when the flyback inverter is connected to the grid, thereby improving the power efficiency and power quality of the power supply system and ensuring the economical and safe operation of the power grid and electrical equipment.

[0050] Reference Figure 2In some embodiments, obtaining the sinusoidal pulse width modulation wave signal of the target power grid in the aforementioned step S100 includes:

[0051] Step S101, obtaining a sine wave signal and a carrier signal of a target power grid; the carrier signal is a triangular wave signal or a sawtooth wave signal; the frequency of the sine wave signal is less than the frequency of the carrier signal;

[0052] Step S102: Compare the sine wave signal with the carrier signal to obtain a sine pulse width modulation wave signal having the same frequency as the sine wave signal.

[0053] The sinusoidal pulse width modulation wave signal can be a voltage modulation wave signal u1 or a current modulation wave signal i0. In this embodiment, the sinusoidal modulation wave signal is a current modulation wave signal as an example. s ) is used as the carrier wave, and the sine wave with the power grid working frequency (f1, 50Hz in China and 60Hz in the United States) is used as the modulation wave. The modulation wave changes in a sinusoidal manner within the half cycle from 0 to π and from π to 2π. The modulation wave with a frequency of f1 is combined with the modulation wave with a frequency of f s The carrier wave is compared to generate f s It is the SPWM (sinusoidal pulse width modulation) waveform of the switching frequency f1, that is, the sine pulse width modulation wave signal, and its waveform is as follows Figure 3 As shown in the waveform of i0, this waveform has the following characteristics: the pulse width is small when the amplitude of the sine wave is small, and the pulse width is large when the amplitude of the sine wave is large, reaching the maximum value at π / 2 and 3π / 2 respectively.

[0054] SPWM technology simulates the shape of a sine wave by generating a group of pulses whose width varies according to the sine law. This technology simulates a sine waveform by adjusting the pulse width. Its basic principle is the area equivalence principle, that is, when a series of narrow pulses with equal impulses but different shapes are added to a link with inertia, the effect is basically the same. This means that by adjusting the width of the pulse, these pulses can be functionally equivalent to the required sine wave. Common sampling methods for SPWM include natural sampling and regular sampling. The natural sampling method calculates the pulse width directly from the intersection of the modulated wave and the carrier, while the regular sampling method simplifies this process and quickly determines the pulse width through a fixed geometric relationship, thereby reducing the computational complexity and improving real-time performance.

[0055] In some embodiments, the frequency and phase of the sinusoidal pulse width modulation wave signal and the pulse wave signal are consistent;

[0056] The waveform of the modified modulation wave signal obtained by performing a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the pulse wave signal includes:

[0057] The frequency and phase of the modified modulation wave signal are kept consistent with those of the sinusoidal pulse width modulation wave signal, the waveform of the sinusoidal pulse width modulation wave signal is logically ANDed with the waveform of the pulse wave signal, and the waveform of the sinusoidal pulse width modulation wave signal within a preset time period is cut off to obtain the waveform of the modified modulation wave signal.

[0058] Specifically, since the pulse wave signal is at a logic low level within a preset time period, when a logic AND operation is performed on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal, the waveform of the obtained modified modulation wave signal is equivalent to the waveform formed after the waveform of the sinusoidal pulse width modulation wave signal is cut off from the waveform within the preset time period.

[0059] In some embodiments, reference Figure 4 , in step S100, obtaining a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period includes:

[0060] Step S103, obtaining the frequency of the sinusoidal pulse width modulation wave signal; specifically, the power grid in this application refers to a system composed of power plants, power transmission lines, substations and distribution facilities and other power devices, and AC is used for power transmission in the power grid.

[0061] Step S104, calculating the duration of the preset time period according to the frequency of the sinusoidal pulse width modulation wave signal and the preset power factor; specifically, determining the corresponding power factor angle according to the preset power factor, and then calculating the width corresponding to the power factor angle and the frequency of the sinusoidal pulse width modulation wave signal to obtain the duration of the preset time period.

[0062] Step S105, using the frequency of the sinusoidal pulse width modulation wave signal as the frequency of the pulse wave signal, and obtaining the pulse wave signal according to the length of the preset time period; specifically, setting the frequency of the pulse wave signal to be the same as the frequency of the sinusoidal pulse width modulation wave signal can ensure that in each half cycle, the waveform of the pulse wave signal maintains a consistent rule when performing a logical AND operation with the waveform of the sinusoidal pulse width modulation wave signal, that is, in each half cycle, the pulse wave signal is at a logical low level within the preset time period.

[0063] In some embodiments, reference Figure 5 , the aforementioned step S104 includes:

[0064] Step S1041, calculating the period of the sinusoidal pulse width modulation wave signal according to the frequency of the sinusoidal pulse width modulation wave signal; specifically, the frequency of the sinusoidal pulse width modulation wave signal is defined as f, then the period of the sinusoidal pulse width modulation wave signal is T=1 / f.

[0065] Step S1042, calculate the duration of the preset time period according to the power factor angle corresponding to the preset power factor and the period of the sinusoidal pulse width modulation wave signal; specifically, the preset power factor is defined as cosφ, then the corresponding power factor angle is φ, then the duration of the preset time period t=(φ / π)*T / 2=φ / 2πf.

[0066] Furthermore, taking the preset power factor of 0.8 and the grid operating frequency of 50 Hz as an example, cosφ=0.8, and the corresponding power factor angle φ is approximately π / 5, then the width of the pulse wave signal at the logic low level can be calculated, that is, within the half cycle, the pulse wave signal is in a logic low level state at the position of 0 to approximately π / 5 (inductive load), or the pulse wave signal is in a logic low level state at the position of approximately 4π / 5 to π (capacitive load).

[0067] In some embodiments, the aforementioned step S105 includes:

[0068] When the load connected to the flyback inverter is an inductive load, the frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, and a pulse wave signal is obtained that is a logic low level between the start point of the half cycle and the power factor angle corresponding to the preset power factor in each half cycle, and is a logic high level between the power factor angle corresponding to the preset power factor and the end point of the half cycle;

[0069] Specifically, refer to Figure 3 and Figure 6 When the load connected to the flyback inverter is an inductive load, it is equivalent to the pulse wave signal lagging behind the sinusoidal pulse width modulation wave signal by an angle φ. The pulse wave signal is a logic low level between 0 to φ and π to π+φ, and a logic high level between φ to π and π+φ to 2π.

[0070] In some embodiments, the aforementioned step S105 may further include:

[0071] When the load connected to the flyback inverter is a capacitive load, the frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, and a pulse wave signal is obtained that is a logic high level between the starting point of the half cycle and the power factor angle corresponding to the preset power factor in each half cycle, and is a logic low level between the power factor angle corresponding to the preset power factor and the end point of the half cycle.

[0072] Specifically, refer to Figure 3 and Figure 7When the load connected to the flyback inverter is a capacitive load, it is equivalent to the pulse wave signal leading the sinusoidal pulse width modulation wave signal by an angle φ. The pulse wave signal is a logic low level between π-φ to π and 2π-φ to 2π, and a logic high level between 0 to π-φ and π to 2π-φ.

[0073] In some embodiments, performing a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal, and removing the waveform of the sinusoidal pulse width modulation wave signal within a preset time period to obtain the waveform of the modified modulation wave signal includes:

[0074] A logic AND operation is performed on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal which is a logic low level in a preset time period and is consistent with the waveform of the sinusoidal pulse width modulation wave signal in a non-preset time period.

[0075] In some embodiments, a waveform of a sinusoidal pulse width modulation wave signal is logically ANDed with a waveform of a pulse wave signal to obtain a waveform of a modified modulation wave signal that is a logic low level in a preset time period and consistent with the waveform of the sinusoidal pulse width modulation wave signal in a non-preset time period, including:

[0076] Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal at a logic low level to obtain a first waveform corresponding to the logic low level;

[0077] Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal at a logic high level to obtain a second waveform consistent with the waveform of the sinusoidal pulse width modulation wave signal;

[0078] A logic OR operation is performed on the first waveform and the second waveform to obtain a waveform of a modified modulated wave signal.

[0079] Specifically, when the waveform of the sinusoidal pulse width modulated wave signal is logically ANDed with a logic low level, the waveform obtained is also the waveform corresponding to the logic low level, which is equivalent to cutting off the waveform of the sinusoidal pulse width modulated wave signal within a preset time period, and when the waveform of the sinusoidal pulse width modulated wave signal is logically ANDed with a logic high level, the waveform of the sinusoidal pulse width modulated wave signal is retained, thereby obtaining a waveform of a modified modulated wave signal that is a logic low level within a preset time period and is consistent with the waveform of the sinusoidal pulse width modulated wave signal within a non-preset time period.

[0080] Further, controlling the flyback inverter to output a target alternating current corresponding to the waveform of the modified modulation wave signal to the target power grid or power-consuming equipment includes:

[0081] When the load connected to the flyback inverter is an inductive load, refer to Figure 6, within one cycle, the target AC power is not pulsated between 0 and φ and π to π+φ, and is pulsated with a waveform of a sinusoidal pulse width modulation wave signal between φ to π and π+φ to 2π;

[0082] Or, when the load connected to the flyback inverter is a capacitive load, refer to Figure 7 In one cycle, the target AC current does not generate a wave between π-φ to π and 2π-φ to 2π, and generates a wave with a waveform of a sinusoidal pulse width modulation wave signal between 0 to π-φ and π to 2π-φ.

[0083] In some embodiments, the frequency of the sinusoidal pulse width modulation wave signal is 50 Hz or 60 Hz.

[0084] In the present embodiment, since the modified modulated wave signal is obtained by synthesizing the sinusoidal pulse width modulated wave signal and the pulse wave, and the synthesis process is equivalent to performing a logical AND operation on the sinusoidal pulse width modulated wave signal and the pulse wave signal, the modified modulated wave signal obtained after the logical AND operation is equivalent to being blocked within the preset time period, that is, there is no driving waveform output within the preset time period, which is equivalent to the waveform within the preset time period being cut off, and the waveform within the non-preset time period is consistent with the waveform of the sinusoidal pulse width modulated wave signal. Therefore, the method in the present invention can also be figuratively referred to as the "AND-cut method", that is, performing a logical AND operation on the sinusoidal pulse width modulated wave signal and the pulse wave signal is figuratively referred to as "cutting off" the modulated wave signal corresponding to the preset time period.

[0085] Furthermore, an embodiment of the present invention also provides an inverter controller, in which a computer program is stored, and the computer program is executed by a processor to implement the aforementioned method for controlling the grid-connected power factor of a flyback inverter.

[0086] In some embodiments, see Figure 8 When the method of the present application is implemented, the inverter controller obtains the sinusoidal pulse width modulation wave signal of the target power grid and the pulse wave signal corresponding to the preset power factor input by the user obtained by the inverter controller and being at a logic low level within a preset time period; then the inverter controller performs a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal that is at a logic low level within a preset time period and consistent with the waveform of the sinusoidal pulse width modulation wave signal within a non-preset time period; finally, the inverter controller inputs the waveform of the generated modified modulation wave signal into the flyback inverter to control the flyback inverter to output the target AC power corresponding to the waveform of the modified modulation wave signal to the target power grid or electrical equipment.

[0087] Specifically, the controller is an inverter controller for controlling a flyback inverter, and the controller includes a microprocessor, which is one of the core components of the controller and is responsible for the overall control and coordination functions. The microprocessor can implement the control algorithm and logic of the flyback inverter, including power regulation, frequency control, voltage regulation, 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 an external system, such as a monitoring system, and a communication interface such as a power grid interface. Through the communication interface, the microprocessor can exchange data and receive instructions with external devices, 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 corresponding decisions based on the monitored conditions, such as switching operating modes or adjusting output parameters.

[0088] As the controlled object of the embodiment, Fig. 9 As shown, the flyback inverter specifically includes a transformer T, switch tubes S0-S2, filter capacitors C1-C3, thyristors SCR1-SCR2, a diode D1 and an inductor L1, wherein Fig. 9 In the circuit structure, MOS tubes or IGBT tubes are respectively arranged on the primary side and the secondary side of the transformer as flyback switch tubes. When the power grid absorbs power, the MOS tube S0 on the primary side of the transformer is used as the main switch to store electric energy in the transformer, and the diode D1 on the secondary side of the transformer is used as the auxiliary switch to perform rectification; when the power grid emits power, the MOS tube S0 on the primary side of the transformer is used as the auxiliary switch to perform rectification, and the diode D1 on the secondary side of the transformer is used as the main switch to store electric energy in the transformer. Fig. 9 The circuit structure also includes a photovoltaic panel, which provides an input voltage for an inverter. The high-frequency flyback switch S0 is composed of a MOS tube or an IGBT tube. S1 and S2 are output power frequency switch tubes, respectively. SCR1 and SCR2 are thyristors, respectively. The power frequency switch tubes S1 and SCR1 are connected in series, S2 and SCR2 are connected in series, and S1 and SCR1 are connected in series in parallel with S2 and SCR2 in series, forming a series circuit as shown in the figure. Fig. 9 In the power frequency switch structure shown, the output power frequency switch tubes are composed of MOS tubes or IGBT tubes, and the controller is connected to the power grid and the input end of the flyback inverter respectively. It should be noted that the circuit diagram described in the present invention is for illustration only, and the present invention does not limit the specific structure of the circuit diagram.

[0089] In summary, the present invention obtains a corrected modulated wave signal by performing a logical AND operation on a pulse wave signal and a sinusoidal pulse width modulation wave signal. Since the pulse wave signal is at a logic low level within a preset time period, the corrected modulated wave signal obtained after performing a logical AND operation with the sinusoidal pulse width modulation wave signal can cut off the part of the current that cannot flow back, so that when the generated corrected modulated wave signal is input into the flyback inverter, the power factor can be accurately adjusted when the flyback inverter is connected to the grid, thereby improving the power efficiency and power quality of the power supply system and ensuring the economical and safe operation of the power grid and electrical equipment.

[0090] The above are only partial or preferred embodiments of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.

Claims

1. A method for controlling the grid-connected power factor of a flyback inverter, characterized in that: include: Acquire a sinusoidal pulse width modulation wave signal of a target power grid, and a pulse wave signal corresponding to a preset power factor and at a logic low level within a preset time period, wherein the duration of the preset time period is calculated by the period of the sinusoidal pulse width modulation wave signal and the power factor angle corresponding to the preset power factor; Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain the waveform of the modified modulation wave signal; Controlling the flyback inverter to output target alternating current corresponding to the modified modulation wave signal waveform to the target power grid or power-consuming equipment; The corresponding power factor angle is determined according to the preset power factor, and the duration of the preset time period is obtained by calculating the width corresponding to the power factor angle and the frequency of the sinusoidal pulse width modulation wave signal.

2. The method for controlling the grid-connected power factor of a flyback inverter according to claim 1, characterized in that: The obtaining of the sinusoidal pulse width modulation wave signal of the target power grid comprises: Acquire a sine wave signal and a carrier signal of a target power grid; the carrier signal is a triangular wave signal or a sawtooth wave signal; the frequency of the sine wave signal is less than the frequency of the carrier signal; The sinusoidal wave signal is compared with the carrier signal to obtain the sinusoidal pulse width modulation wave signal having the same frequency as the sinusoidal wave signal.

3. The method for controlling the grid-connected power factor of a flyback inverter according to claim 1, characterized in that: The frequency and phase of the sinusoidal pulse width modulation wave signal and the pulse wave signal are consistent; The step of performing a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain the waveform of the modified modulation wave signal comprises: The frequency and phase of the modified modulation wave signal are kept consistent with those of the sinusoidal pulse width modulation wave signal, a logic AND operation is performed on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal, and the waveform of the sinusoidal pulse width modulation wave signal within a preset time period is cut off to obtain the waveform of the modified modulation wave signal.

4. The method for controlling the grid-connected power factor of a flyback inverter according to claim 3, characterized in that: Acquiring a pulse wave signal corresponding to a preset power factor and being at a logic low level within a preset time period includes: Acquire the frequency of the sinusoidal pulse width modulation wave signal; Calculating the duration of the preset time period according to the frequency of the sinusoidal pulse width modulation wave signal and the preset power factor; The frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, and the pulse wave signal is obtained according to the length of the preset time period.

5. The method for controlling the grid-connected power factor of a flyback inverter according to claim 4, characterized in that: The step of calculating the duration of the preset time period according to the frequency of the sinusoidal pulse width modulation wave signal and the preset power factor comprises: Calculating the period of the sinusoidal pulse width modulation wave signal according to the frequency of the sinusoidal pulse width modulation wave signal; The duration of the preset time period is calculated according to the power factor angle corresponding to the preset power factor and the period of the sinusoidal pulse width modulation wave signal.

6. The method for controlling the grid-connected power factor of a flyback inverter according to claim 5, characterized in that: The step of using the frequency of the sinusoidal pulse width modulation wave signal as the frequency of the pulse wave signal and obtaining the pulse wave signal according to the duration of the preset time period comprises: When the load connected to the flyback inverter is an inductive load, the frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, so as to obtain a pulse wave signal that is at a logic low level between the start point of the half cycle and the power factor angle corresponding to the preset power factor, and at a logic high level between the power factor angle corresponding to the preset power factor and the end point of the half cycle in each half cycle; Alternatively, when the load connected to the flyback inverter is a capacitive load, the frequency of the sinusoidal pulse width modulation wave signal is used as the frequency of the pulse wave signal, and a pulse wave signal is obtained that is a logic high level between the starting point of the half cycle and the power factor angle corresponding to the preset power factor in each half cycle, and a logic low level between the power factor angle corresponding to the preset power factor and the end point of the half cycle.

7. The method for controlling the grid-connected power factor of a flyback inverter according to claim 6, characterized in that: The step of performing a logical AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal, and removing the waveform of the sinusoidal pulse width modulation wave signal within a preset time period to obtain the waveform of the modified modulation wave signal comprises: A logic AND operation is performed on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal which is a logic low level in a preset time period and is consistent with the waveform of the sinusoidal pulse width modulation wave signal in a non-preset time period.

8. The method for controlling the grid-connected power factor of a flyback inverter according to claim 7, characterized in that: The waveform of the sinusoidal pulse width modulation wave signal is subjected to a logic AND operation with the waveform of the pulse wave signal to obtain a waveform of a modified modulation wave signal which is at a logic low level in a preset time period and is consistent with the waveform of the sinusoidal pulse width modulation wave signal in a non-preset time period, including: Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal at a logic low level to obtain a first waveform corresponding to the logic low level; Performing a logic AND operation on the waveform of the sinusoidal pulse width modulation wave signal and the waveform of the pulse wave signal at a logic high level to obtain a second waveform consistent with the waveform of the sinusoidal pulse width modulation wave signal; A logical OR operation is performed on the first waveform and the second waveform to obtain the waveform of the modified modulated wave signal.

9. The method for controlling the grid-connected power factor of a flyback inverter according to any one of claims 1 to 8, characterized in that: The frequency of the sinusoidal pulse width modulation wave signal is 50 Hz or 60 Hz.

10. An inverter controller, characterized in that: The inverter controller stores a computer program, and the computer program is executed by a processor to implement the method for controlling the grid-connected power factor of a flyback inverter according to any one of claims 1 to 9.

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