CN116526813A - A single-phase bridge rectifier input current third harmonic suppression method and system - Google Patents

Abstract

The invention discloses a method and a system for inhibiting third harmonic of input current of a single-phase bridge rectifier, wherein the method comprises the following steps: collecting voltage real-time value u of power grid _s And calculates the voltage amplitude U _sm The method comprises the steps of carrying out a first treatment on the surface of the Based on the electric compacting time value u _s Acquiring a voltage vector angle theta of a power grid through a phase-locked loop; generating a cosine signal cos theta based on the voltage vector angle theta; output direct-current voltage command U based on preset _dc ^* Obtaining an active current instruction I of the power grid through a voltage outer loop control loop _sd ^* The method comprises the steps of carrying out a first treatment on the surface of the Based on voltage amplitude U _sm Cosine signal cos theta and power grid active current command I _sd ^* Predicting power fluctuation of a power grid; based on the predicted power fluctuation of the power grid, predicting voltage ripple in the output voltage by combining hardware parameters of the single-phase PWM rectifier; output voltage compacting value U for superimposing voltage ripple to control system _dc Through electricityPressing the outer ring to obtain an active value instruction I of the power grid current _sd ^* The method comprises the steps of carrying out a first treatment on the surface of the Instruction I based on power grid current active value _sd ^* The third harmonic of the input current of the single-phase PWM rectifier is suppressed.

Description

A single-phase bridge rectifier input current third harmonic suppression method and system

technical field

The present invention relates to the technical field of single-phase pulse width modulation PWM rectifiers, and more specifically, to a method and system for suppressing the third harmonic of input current of a single-phase bridge rectifier.

Background technique

Single-phase pulse width modulation PWM rectifier is a relatively common AC-DC conversion topology. The power factor is controllable, which can realize the bidirectional flow of energy; the grid input current has high sine degree and low harmonic; the output bus voltage is controllable. It is widely used in the pre-stage rectification of various small and medium power AC-DC-DC power supplies, and has a very wide range of applications in the fields of communication power supplies, superconducting energy storage, uninterruptible power supplies, and special power supplies.

Since the single-phase input power has a periodic pulsation of twice the power frequency, there will inevitably be a corresponding double power frequency ripple component in the output DC voltage. After these double power frequency ripples are introduced into the control system, they will eventually cause power grid Distortion of the current waveform, large third harmonics appear, increase the total harmonic distortion of the current, and affect the power quality of the grid.

In order to reduce the impact of the output voltage ripple on the grid current, the traditional approach is to introduce a low-pass filter in the feedback loop, but this will reduce the bandwidth of the system and affect the response speed of the converter. Therefore, a technology is needed to suppress the third harmonic of the input current of the single-phase bridge rectifier.

Contents of the invention

The technical solution of the present invention provides a method and system for suppressing the third harmonic of the input current of a single-phase bridge rectifier to solve the problem of how to suppress the third harmonic of the input current of the single-phase bridge rectifier.

In order to solve the above problems, the invention provides a method for suppressing the third harmonic of the input current of a single-phase bridge rectifier, said method comprising:

Collect the real-time voltage value u _s of the grid, and calculate the voltage amplitude U _sm ;

Based on the voltage real-time value u _s through a phase-locked loop, the voltage vector angle θ of the grid is obtained; based on the voltage vector angle θ, a cosine signal cosθ is generated;

Based on the preset output DC voltage command U _dc ^* , the grid active current command I _sd ^* is obtained through the voltage outer loop control loop; based on the voltage amplitude U _sm , the cosine signal cosθ and the grid active current command I _sd ^* predicts grid power fluctuations;

Based on the predicted grid power fluctuations, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier, the voltage ripple in the output voltage is predicted;

Superimpose the voltage ripple to the real-time value U _dc of the output voltage of the control system, and obtain the grid current active value command I _sd ^* through the voltage outer loop; based on the grid current active value command I _sd ^* , single-phase pulse width modulation The third harmonic of the input current of the PWM rectifier is suppressed.

Preferably, the acquisition of the grid voltage vector angle θ through a phase-locked loop based on the real-time voltage value u _s includes:

Map the real-time voltage value u _s to the two-phase stationary coordinate system to get u _sα , delay the real-time voltage value u _s by 90° to get u _sβ , and transform u _sα and u _sβ to get u _sd , u in the two-phase rotating coordinate system _sq ; u _sq is controlled to 0 by the control system, and the speed feedforward of 314rad/s is added, and the vector angle θ of the grid voltage is obtained through integration.

Preferably, the predicted grid power fluctuation is:

Among them, p _s is the real-time power of the power grid, θ=ωt, ω is the angular frequency of the grid voltage, t is time, and _Δps is the fluctuation component of power.

Preferably, the voltage ripple in the predicted output voltage is:

Among them, θ=ωt, ω is the grid voltage angular frequency, t is time, U _dc ^* is the output voltage command value, C is the output filter capacitor of the single-phase pulse width modulation PWM rectifier.

Preferably, the grid current active value command I _sd ^* is:

Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted voltage ripple.

Based on another aspect of the present invention, the present invention provides a single-phase bridge rectifier input current third harmonic suppression system, said system comprising:

The initial unit is used to collect the real-time value u _s of the grid voltage and calculate the voltage amplitude U _sm ;

The execution unit is used to obtain the voltage vector angle θ of the power grid through the phase-locked loop based on the real-time voltage value u _s ; based on the voltage vector angle θ, generate a cosine signal cosθ; based on the preset output DC voltage command U _dc ^* , the grid active current command I _sd ^* is obtained through the voltage outer loop control loop; based on the voltage amplitude U _sm , the cosine signal cosθ and the grid active current command I _sd ^* , the grid power fluctuation is predicted; based on the prediction The grid power fluctuation, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier, predicts the voltage ripple in the output voltage;

The result unit is used to superimpose the voltage ripple to the real-time value U _dc of the output voltage of the control system, and obtain the grid current active value command I _sd ^* through the voltage outer loop; based on the grid current active value command I _sd ^* for The third harmonic of the input current of the single-phase pulse width modulated PWM rectifier is suppressed.

Preferably, the execution unit is configured to acquire the vector angle θ of the grid voltage through a phase-locked loop based on the real-time voltage value u _s , including:

Map the real-time voltage value u _s to the two-phase stationary coordinate system to get u _sα , delay the real-time voltage value u _s by 90° to get u _sβ , and transform u _sα and u _sβ to get u _sd , u in the two-phase rotating coordinate system _sq ; u _sq is controlled to 0 by the control system, and the speed feedforward of 314rad/s is added, and the vector angle θ of the grid voltage is obtained through integration.

Preferably, the predicted grid power fluctuation is:

Among them, p _s is the real-time power of the power grid, θ=ωt, ω is the angular frequency of the grid voltage, t is time, and _Δps is the fluctuation component of power.

Preferably, the voltage ripple in the predicted output voltage is:

Among them, θ=ωt, ω is the grid voltage angular frequency, t is time, U _dc ^* is the output voltage command value, C is the output filter capacitor of the single-phase pulse width modulation PWM rectifier.

Preferably, the grid current active value command I _sd ^* is:

Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted voltage ripple.

The present invention provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and the computer program is used to implement the above-mentioned method for suppressing the third harmonic of the input current of a single-phase bridge rectifier.

The present invention provides an electronic device, and the electronic device includes: a processor and a memory; wherein,

memory for storing processor-executable instructions;

The processor is used for reading executable instructions from the memory, and executing the instructions to realize the above-mentioned method for suppressing the third harmonic of the input current of a single-phase bridge rectifier.

The technical scheme of the present invention provides a single-phase bridge rectifier input current third harmonic suppression method and system, wherein the method includes: collecting the voltage real-time value u _s of the power grid, and calculating the voltage amplitude U _sm ; based on the voltage real-time value u _s Through the phase-locked loop, the voltage vector angle θ of the grid is obtained; based on the voltage vector angle θ, the cosine signal cosθ is generated; based on the preset output DC voltage command U _dc ^* , the active current command I _sd of the grid is obtained through the voltage outer loop control loop ^* ; Based on voltage amplitude U _sm , cosine signal cosθ and grid active current command I _sd ^* , predict grid power fluctuations; based on predicted grid power fluctuations, combined with hardware parameters of single-phase pulse width modulation PWM rectifiers, predict output voltage The voltage ripple; the voltage ripple is superimposed on the real-time value U _dc of the output voltage of the control system, and the grid current active value command I _sd ^* is obtained through the voltage outer loop; the single-phase pulse width modulation is based on the grid current active value command I _sd ^* The third harmonic of the input current of the PWM rectifier is suppressed. The technical solution of the present invention does not need to add an output current sensor, only starts from the existing data, optimizes the algorithm, does not increase the hardware cost, is applicable to different load conditions, and realizes the effective suppression of the third harmonic of the grid current.

Description of drawings

A more complete understanding of the exemplary embodiments of the present invention can be had by referring to the following drawings:

Fig. 1 is a flow chart of a method for suppressing the third harmonic of a single-phase bridge rectifier input current according to a preferred embodiment of the present invention;

Fig. 2 is a flow chart of a method for suppressing the third harmonic of the input current of a single-phase bridge rectifier according to a preferred embodiment of the present invention;

Fig. 3 is the main circuit topological diagram provided according to a kind of single-phase high-frequency pulse width modulation PWM rectifier input current third harmonic suppression method according to the preferred embodiment of the present invention;

4 is a voltage and current control block diagram provided by the single-phase high-frequency pulse width modulation PWM rectifier input current third harmonic suppression method according to a preferred embodiment of the present invention;

Fig. 5 is according to not using the grid input current THD of the preferred embodiment of the present invention;

Fig. 6 is grid input current THD according to a preferred embodiment of the present invention;

Fig. 7 is a structural diagram of a third harmonic suppression system for input current of a single-phase bridge rectifier according to a preferred embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the drawings; however, the present invention may be embodied in many different forms and are not limited to the embodiments described herein, which are provided for the purpose of exhaustively and completely disclosing the present invention. invention and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings do not limit the present invention. In the figures, the same units/elements are given the same reference numerals.

Unless otherwise specified, the terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it can be understood that terms defined by commonly used dictionaries should be understood to have consistent meanings in the context of their related fields, and should not be understood as idealized or overly formal meanings.

Fig. 1 is a flowchart of a method for suppressing the third harmonic of input current of a single-phase bridge rectifier according to a preferred embodiment of the present invention. Aiming at the defects and improvement needs of the prior art, the present invention provides a method for suppressing the third harmonic of the input current of a single-phase high-frequency pulse width modulation PWM rectifier, which improves the influence of the output DC voltage twice the power frequency ripple on the input side power grid current, At the same time, the problem of slow system response caused by the existing solution of adding a low-pass filter in the control loop is improved. The present invention performs current third harmonic suppression based on FIG. 3 .

As shown in Figure 1, the present invention provides a method for suppressing the third harmonic of the input current of a single-phase bridge rectifier, the method comprising:

Step 101: collect the real-time value u _s of the grid voltage, and calculate the voltage amplitude U _sm ;

In step 101 of the present invention: collect the real-time voltage and current values of the power grid to obtain its amplitude and phase information. The voltage and current information on the grid side, the real-time voltage value u _s and the real-time current value is is collected through the sensor, and the effective value of the grid voltage U _s , the effective value of the current I _s , the voltage amplitude _{U sm ,} and the current amplitude I _sm are calculated.

Step 102: Obtain the voltage vector angle θ of the power grid through the phase-locked loop based on the real-time voltage value u _s ; generate a cosine signal cosθ based on the voltage vector angle θ;

Preferably, based on the real-time voltage value u _s , the vector angle θ of the grid voltage is obtained through a phase-locked loop, including:

Map the real-time voltage value u _s to the two-phase stationary coordinate system to get u _sα , delay the real-time voltage value u _s by 90° to get u _sβ , and transform u _sα and u _sβ to get u _sd , u in the two-phase rotating coordinate system _sq ; u _sq is controlled to 0 by the control system, and the speed feedforward of 314rad/s is added, and the vector angle θ of the grid voltage is obtained through integration.

In step 102, according to the real-time voltage value u _s obtained in step 101, the present invention uses a phase-locked loop to obtain the vector angle θ of the grid voltage, and generates a set of sinθ and cosine signals sinθ, cosθ.

In step 102, the present invention maps the real-time voltage value u _s to the two-phase stationary coordinate system to obtain u _sα , delays the real-time voltage value u _s by 90° to obtain u _sβ , and performs coordinate transformation on u _sα and u _sβ to obtain two-phase rotating coordinates Department of u _sd , u _sq . The control system controls u _sq to 0, plus the speed feedforward of 314rad/s, and integrates to obtain the grid voltage vector angle θ.

Step 103: Based on the preset output DC voltage command U _dc ^* , the grid active current command I _sd ^* is obtained through the voltage outer loop control loop; based on the voltage amplitude U _sm , the cosine signal cosθ and the grid active current command I _sd ^* Grid power fluctuations are predicted;

Preferably, the predicted grid power fluctuation is:

Among them, p _s is the real-time power of the power grid, θ=ωt, ω is the angular frequency of the grid voltage, t is time, and _Δps is the fluctuation component of power.

In step 103, the present invention obtains the grid voltage real-time value U _sm cosθ based on cosθ in step 102 and U _sm in S1; and obtains grid active power through a voltage outer loop control loop based on a given output DC voltage command U _dc ^* Current command I _sd ^* , and get the predicted grid current real-time value I _sd ^* cosθ, and predict the power fluctuation of the grid.

The grid voltage real-time value U _sm cosθ used in step 103 of the present invention is a calculated value calculated based on the grid voltage effective value and the vector angle θ, not the real-time value sampled by the grid voltage sensor.

The grid power expression that the present invention predicts is:

Among them, p _s is the real-time power of the grid, U _sm is the amplitude of the grid voltage, I _sd ^* is the current loop command, θ is the vector angle of the grid voltage, θ=ωt, and ω is the angular frequency of the grid voltage.

Step 104: Predict the voltage ripple in the output voltage based on the predicted grid power fluctuations, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier;

Preferably, the voltage ripple in the predicted output voltage is:

Among them, θ=ωt, ω is the grid voltage angular frequency, t is time, U _dc ^* is the output voltage command value, C is the output filter capacitor of the single-phase pulse width modulation PWM rectifier.

In step 104 of the present invention, according to the grid power fluctuation predicted in step 103, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier, the amplitude and phase of twice the power frequency ripple that will be included in the output voltage are predicted.

The current information used to predict the grid power fluctuation in step 103 of the present invention is the active current command I _sd ^* obtained by the DC voltage command U _dc ^* through the control loop, not the real-time value sampled by the grid current sensor, and is only used for Unity power factor operating conditions.

The output voltage ripple expression that the present invention predicts is:

Among them, U _sm is the amplitude of grid voltage, I _sd ^* is the current loop command, θ is the vector angle of grid voltage, θ=ωt, ω is the angular frequency of grid voltage, U _dc ^* is the command value of output voltage, and C is single-phase Output Filter Capacitor for Pulse Width Modulation PWM Rectifier. U _dc ^* is used instead of the real-time sampled value U _dc of the output voltage for calculation to avoid introducing ripples in the output voltage into the control system.

Step 105: Superimpose the voltage ripple to the real-time value U _dc of the output voltage of the control system, and obtain the grid current active value command I _sd ^* through the voltage outer loop; based on the grid current active value command I _sd ^* , single-phase pulse width modulation PWM The third harmonic of the input current of the rectifier is suppressed.

Preferably, the grid current active value command I _sd ^* is:

Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted voltage ripple.

In step 105 of the present invention, the output voltage ripple predicted in step 104 is reversed, superimposed on the real-time value U _dc of the output voltage injected into the control system, and through the voltage outer loop, the grid current active value command I _sd ^* is obtained, suppressing The influence of twice the power frequency ripple in the output voltage suppresses the third harmonic of the grid side current, and the final spwm signal is obtained through PI control and coordinate transformation. As shown in Figure 4.

The ripple in the output voltage in step 104 of the present invention is a predicted predicted value based on power fluctuation at the grid side, not a real-time value sampled by the output voltage sensor.

The output voltage ripple predicted in step 105 of the present invention is reversed and superimposed on the real-time value of the output voltage of the injection control system without passing through a low-pass filter, thereby ensuring the response speed of the system.

The grid current active value instruction expression of the present invention is:

Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted output voltage ripple.

The invention provides a single-phase high-frequency pulse width modulation PWM rectifier input current third harmonic suppression method, by predicting the power fluctuation of the power grid, predicting the ripple of the DC output voltage, and superimposing it on the output voltage collected by the sensor in real time In terms of values, they are also sent to the control system to suppress the influence of the output voltage ripple on the control system. The active current component command value I _sd ^* is obtained through PI control, and the third harmonic of the input current of the single-phase high-frequency pulse width modulation PWM rectifier is suppressed. The present invention does not depend on the low-pass filter to attenuate the output DC voltage ripple, and will not affect the bandwidth of the system. The hardware cost is suitable for different load conditions, and the effective suppression of the third harmonic of the grid current is realized.

The invention proposes a single-phase high-frequency pulse width modulation PWM rectifier input current third harmonic suppression method, the input current third harmonic can be reduced by 80%;

The invention proposes a harmonic prediction method, which uses command values instead of actual sampling values for calculation during prediction, and avoids the influence of harmonic components in actual parameters.

The present invention provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and the computer program is used to implement the above-mentioned method for suppressing the third harmonic of the input current of a single-phase bridge rectifier.

The present invention provides an electronic device, and the electronic device includes: a processor and a memory; wherein,

memory for storing processor-executable instructions;

The processor is used for reading executable instructions from the memory, and executing the instructions to realize the above-mentioned method for suppressing the third harmonic of the input current of a single-phase bridge rectifier.

Fig. 7 is a structural diagram of a third harmonic suppression system for input current of a single-phase bridge rectifier according to a preferred embodiment of the present invention.

As shown in Figure 7, the present invention provides a single-phase bridge rectifier input current third harmonic suppression system, said system comprising:

The initial unit 701 is used to collect the real-time value u _s of the grid voltage and calculate the voltage amplitude U _sm ;

The execution unit 702 is used to obtain the voltage vector angle θ of the power grid through a phase-locked loop based on the real-time voltage value u _s ; generate a cosine signal cosθ based on the voltage vector angle θ; output a DC voltage command U _dc based on a preset ^* , the grid active current command I _sd ^* is obtained through the voltage outer loop control loop; the grid power fluctuation is predicted based on the voltage amplitude U _sm , the cosine signal cosθ and the grid active current command I _sd ^* ; The predicted grid power fluctuation, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier, predicts the voltage ripple in the output voltage;

Preferably, the predicted grid power fluctuation is:

Among them, p _s is the real-time power of the power grid, θ=ωt, ω is the angular frequency of the grid voltage, t is time, and _Δps is the fluctuation component of power.

Preferably, the voltage ripple in the predicted output voltage is:

Among them, θ=ωt, ω is the grid voltage angular frequency, t is time, U _dc ^* is the output voltage command value, C is the output filter capacitor of the single-phase pulse width modulation PWM rectifier.

Preferably, the grid current active value command I _sd ^* is:

Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted voltage ripple.

The result unit 703 is used to superimpose the voltage ripple on the real-time value U _dc of the output voltage of the control system, and obtain the grid current active value command I _sd ^* through the voltage outer loop; based on the grid current active value command I _sd ^* The third harmonic of the input current of the single-phase pulse width modulation PWM rectifier is suppressed.

Preferably, the execution unit 702 is configured to obtain the vector angle θ of the grid voltage through a phase-locked loop based on the real-time voltage value u _s , including:

Map the real-time voltage value u _s to the two-phase stationary coordinate system to get u _sα , delay the real-time voltage value u _s by 90° to get u _sβ , and transform u _sα and u _sβ to get u _sd , u in the two-phase rotating coordinate system _sq ; u _sq is controlled to 0 by the control system, and the speed feedforward of 314rad/s is added, and the vector angle θ of the grid voltage is obtained through integration.

The present invention provides a single-phase bridge rectifier input current third harmonic suppression system corresponding to the present invention provides a single-phase bridge rectifier input current third harmonic suppression method, which will not be repeated here.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein. The solutions in the embodiments of the present invention can be realized by using various computer languages, for example, the object-oriented programming language Java and the literal translation scripting language JavaScript.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

While preferred embodiments of the invention have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, it is intended that the appended claims be construed to cover the preferred embodiment as well as all changes and modifications which fall within the scope of the invention.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

The invention has been described with reference to a small number of embodiments. However, it is clear to a person skilled in the art that other embodiments than the invention disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a/the/the [means, component, etc.]" are openly construed to mean at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (12)

1. a single-phase bridge rectifier input current third harmonic suppression method, said method comprising: Collect the real-time voltage value u _s of the grid, and calculate the voltage amplitude U _sm ; Based on the voltage real-time value u _s through a phase-locked loop, the voltage vector angle θ of the grid is obtained; based on the voltage vector angle θ, a cosine signal cosθ is generated; Based on the preset output DC voltage command U _dc ^* , the grid active current command I _sd ^* is obtained through the voltage outer loop control loop; based on the voltage amplitude U _sm , the cosine signal cosθ and the grid active current command I _sd ^* predicts grid power fluctuations; Based on the predicted grid power fluctuations, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier, the voltage ripple in the output voltage is predicted; Superimpose the voltage ripple to the real-time value U _dc of the output voltage of the control system, and obtain the grid current active value command I _sd ^* through the voltage outer loop; based on the grid current active value command I _sd ^* , single-phase pulse width modulation The third harmonic of the input current of the PWM rectifier is suppressed. 2. The method according to claim 1, said based on said voltage real-time value u _s , through a phase-locked loop, to obtain the vector angle θ of grid voltage, comprising: Map the real-time voltage value u _s to the two-phase stationary coordinate system to get u _sα , delay the real-time voltage value u _s by 90° to get u _sβ , and transform u _sα and u _sβ to get u _sd , u in the two-phase rotating coordinate system _sq ; u _sq is controlled to 0 by the control system, and the speed feedforward of 314rad/s is added, and the vector angle θ of the grid voltage is obtained through integration. 3. The method according to claim 1, the predicted grid power fluctuation is: Among them, p _s is the real-time power of the power grid, θ=ωt, ω is the angular frequency of the grid voltage, t is time, and _Δps is the fluctuation component of power. 4. The method according to claim 1, the voltage ripple in the predicted output voltage is: Among them, θ=ωt, ω is the grid voltage angular frequency, t is time, U _dc ^* is the output voltage command value, C is the output filter capacitor of the single-phase pulse width modulation PWM rectifier. 5. The method according to claim 1, the grid current active value command I _sd ^* is: Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted voltage ripple. 6. A single-phase bridge rectifier input current third harmonic suppression system, said system comprising: The initial unit is used to collect the real-time value u _s of the grid voltage and calculate the voltage amplitude U _sm ; The execution unit is used to obtain the voltage vector angle θ of the power grid through a phase-locked loop based on the real-time voltage value u _s ; based on the voltage vector angle θ, generate a cosine signal cosθ; based on the preset output DC voltage command U _dc ^* , the grid active current command I _sd ^* is obtained through the voltage outer loop control loop; based on the voltage amplitude U _sm , the cosine signal cosθ and the grid active current command I _sd ^* , the grid power fluctuation is predicted; based on the prediction The grid power fluctuation, combined with the hardware parameters of the single-phase pulse width modulation PWM rectifier, predicts the voltage ripple in the output voltage; The result unit is used to superimpose the voltage ripple to the real-time value U _dc of the output voltage of the control system, and obtain the grid current active value command I _sd ^* through the voltage outer loop; based on the grid current active value command I _sd ^* for The third harmonic of the input current of the single-phase pulse width modulated PWM rectifier is suppressed. 7. The system according to claim 6, the execution unit is configured to acquire the vector angle θ of the grid voltage through a phase-locked loop based on the real-time voltage value u _s , comprising: Map the real-time voltage value u _s to the two-phase stationary coordinate system to get u _sα , delay the real-time voltage value u _s by 90° to get u _sβ , and transform u _sα and u _sβ to get u _sd , u in the two-phase rotating coordinate system _sq ; u _sq is controlled to 0 by the control system, and the speed feedforward of 314rad/s is added, and the vector angle θ of the grid voltage is obtained through integration. 8. The system according to claim 6, the predicted grid power fluctuation is: Among them, p _s is the real-time power of the power grid, θ=ωt, ω is the angular frequency of the grid voltage, t is time, and _Δps is the fluctuation component of power. 9. The system of claim 6, the predicted voltage ripple in the output voltage is: Among them, θ=ωt, ω is the grid voltage angular frequency, t is time, U _dc ^* is the output voltage command value, C is the output filter capacitor of the single-phase pulse width modulation PWM rectifier. 10. The system according to claim 6, the grid current active value instruction I _sd ^* is: Among them, K _p and K _i are the parameters of the PI controller, s is the Laplacian operator, U _dc ^* is the DC voltage command, U _dc is the real-time sampled value of the output voltage, and Δu _dc is the predicted voltage ripple. 11. A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and the computer program is used to execute the method according to any one of claims 1-5. 12. An electronic device, characterized in that the electronic device comprises: a processor and a memory; wherein, the memory for storing memory executable by the processor; The processor is configured to read the executable instruction from the memory, and execute the instruction to implement the method according to any one of claims 1-5.