CN118337077A - Control method and device for direct current inverter and direct current inverter - Google Patents

Abstract

The application relates to the technical field of frequency conversion, and discloses a control method for a direct current inverter, which comprises the following steps: under the condition that the inverter works normally, detecting the voltage frequency of the direct current side of the inverter in real time; judging whether a first driving signal of the DC side voltage of the inverter needs to be modulated or not according to the real-time voltage frequency and the frequency threshold value; the frequency threshold is used for identifying high and low frequencies of direct-current side voltage, and the first driving signal is a driving signal based on a standard sinusoidal signal; and if so, acquiring a modulated second driving signal and controlling the inverter to work under the second driving signal. The method identifies a modulation occasion of the drive signal based on the frequency threshold. The harmonic distortion degree of the output voltage of the frequency converter is reduced when the voltage frequency of the direct current side is higher and lower. The application also discloses a control device for the direct current inverter, the direct current inverter and a storage medium.

Description

Control method and device for direct current inverter and direct current inverter

Technical Field

The present application relates to the field of inverter technology, and for example, to a control method and apparatus for a dc inverter, and a storage medium.

Background

In the current inversion occasion, the instantaneous power of the AC side and the DC side of the inverter is unbalanced. This causes the doubled ripple power to radiate to the dc side, where the voltage is present at the doubled ripple voltage. In order to ensure that the ripple voltage on the dc side is within a certain range (i.e., the ripple ratio is smaller than a certain value), it is generally necessary to connect an electrolytic capacitor having a larger capacitance value in parallel to the dc side. However, as the power increases and the frequency decreases, the ripple voltage on the dc side gradually increases, resulting in an increase in the degree of harmonic distortion on the ac side.

The related art discloses a method for suppressing voltage fluctuation at the DC side of an inverter, which comprises the following steps: (1) The total direct current side voltage control is used for realizing that the direct current side voltage of each H bridge unit tracks the maximum power point voltage of the H bridge unit and obtaining the active current instruction value of the system; (2) The decoupling control of the network side current can realize the independent control of active current and reactive current and generate an original modulation signal of the inverter; (3) And (3) suppressing direct-current side voltage fluctuation control, and correcting the three-phase original modulation signal by injecting third harmonic wave to reduce H bridge direct-current side voltage fluctuation.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

Modulation voltage fluctuation is corrected through decoupling control and third harmonic, but the control is relatively complex, and the realization difficulty is high.

It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview, and is intended to neither identify key/critical elements nor delineate the scope of such embodiments, but is intended as a prelude to the more detailed description that follows.

The embodiment of the disclosure provides a control method and device for a direct current inverter, the direct current inverter and a storage medium, and the degree of harmonic distortion of alternating current measurement of a frequency converter is reduced by a relatively simple control method.

In some embodiments, the method comprises: under the condition that the inverter works normally, detecting the voltage frequency of the direct current side of the inverter in real time; judging whether a first driving signal of the DC side voltage of the inverter needs to be modulated or not according to the real-time voltage frequency and the frequency threshold value; the frequency threshold is used for identifying high and low frequencies of direct-current side voltage, and the first driving signal is a driving signal based on a standard sinusoidal signal; and if so, acquiring a modulated second driving signal and controlling the inverter to work under the second driving signal.

In some embodiments, the apparatus comprises: a processor and a memory storing program instructions, the processor being configured to perform the control method for a dc-inverter as described before when the program instructions are run.

In some embodiments, the dc inverter includes: a DC inverter body; and the control device for a dc inverter as described above is mounted to the dc inverter body.

In some embodiments, the storage medium stores program instructions that, when executed, perform a control method for a dc-dc converter as previously described.

The control method and device for the direct current inverter, the direct current inverter and the storage medium provided by the embodiment of the disclosure can realize the following technical effects:

In the disclosed embodiment, the voltage frequency on the dc side of the inverter is detected in real time and compared to a frequency threshold. To determine whether the real-time voltage frequency is a high frequency or a low frequency, and thus whether the first driving signal based on the standard sinusoidal signal needs to be modulated. The first drive signal is modulated and the inverter is controlled to operate on the modulated second drive signal, if necessary. In this manner, the modulation timing of the drive signal is identified based on the frequency threshold. The harmonic distortion degree of the output voltage of the frequency converter is reduced when the voltage frequency of the direct current side is higher and lower. And the control method is relatively simple and easy to realize.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which like reference numerals refer to similar elements, and in which:

fig. 1 is a schematic diagram of a control method for a dc inverter provided by an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a method for obtaining a modulated second driving signal according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of another control method for a dc inverter provided by an embodiment of the present disclosure;

fig. 4 is a schematic diagram of another control method for a dc inverter provided by an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of frequency acquisition of an embodiment of the present disclosure;

Fig. 6 is a schematic diagram of another control method for a dc inverter provided by an embodiment of the present disclosure;

fig. 7 is a schematic diagram of a control apparatus for a dc inverter provided in an embodiment of the present disclosure;

fig. 8 is a schematic diagram of a dc converter according to an embodiment of the disclosure.

Detailed Description

So that the manner in which the features and techniques of the disclosed embodiments can be understood in more detail, a more particular description of the embodiments of the disclosure, briefly summarized below, may be had by reference to the appended drawings, which are not intended to be limiting of the embodiments of the disclosure. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may still be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawing.

The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present disclosure. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

The term "plurality" means two or more, unless otherwise indicated.

In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B.

The term "and/or" is an associative relationship that describes an object, meaning that there may be three relationships. For example, a and/or B, represent: a or B, or, A and B.

The term "corresponding" may refer to an association or binding relationship, and the correspondence between a and B refers to an association or binding relationship between a and B.

As shown in fig. 1, an embodiment of the present disclosure provides a control method for a dc inverter, including:

s101, under the condition that the inverter works normally, the processor detects the voltage frequency of the direct current side of the inverter in real time.

S102, the processor judges whether the first driving signal of the DC side voltage of the inverter needs to be modulated or not according to the real-time voltage frequency and the frequency threshold value. The frequency threshold is used for identifying high and low frequencies of the direct-current side voltage, and the first driving signal is a driving signal based on a standard sinusoidal signal.

And S103, if so, the processor acquires the modulated second driving signal and controls the inverter to work under the second driving signal.

Here, the processor may be an FPGA (Filed Programmable GATE ARRAY, field programmable logic array). The FPGA is provided with a sampling circuit, so that the voltage frequency of the DC side of the inverter can be detected in real time. And further judging whether the first driving signal on the DC side of the inverter needs to be modulated or not based on the acquired real-time voltage frequency and the frequency threshold value. Wherein, when the inverter is in operation, a driving signal (i.e., a first driving signal) is input to the dc side voltage input terminal of the inverter. The first drive signal is a drive signal based on a standard sinusoidal signal. Therefore, the dc side voltage frequency collected by the sampling circuit is the voltage frequency including the driving signal. It will be appreciated that the voltage on the dc side is almost constant without ripple in the absence of a drive signal. At this time, the acquisition of the voltage frequency on the direct current side is not significant for the harmonic distortion adjustment of the output voltage. In the embodiment of the present disclosure, therefore, the detection of the dc side voltage frequency is based on the voltage frequency detection of the driving signal.

Along with the reduction of the voltage frequency of the direct current side of the frequency converter, the voltage ripple of the double frequency voltage on the direct current side DC-Link capacitor is gradually increased, and the increase of the voltage ripple of the direct current side can lead to the increase of the THD (Total Harmonic Distortion, harmonic distortion) of the alternating current side. Accordingly, a frequency threshold is set to identify high and low of the dc side voltage frequency. To modulate the first drive signal at low frequencies. The inverter is controlled to work under the modulated second driving signal, so that the harmonic distortion degree of the output voltage caused by low frequency is reduced. Wherein, the direct current side voltage signal is modulated by adopting an active closed loop mode. The frequency threshold can be obtained through multiple tests, namely, when the distortion degree of the output voltage is heavy, the corresponding DC side voltage frequency range is tested through the tests. The frequency range or one of the fixed values is taken as the frequency threshold.

By adopting the control method for the direct current inverter provided by the embodiment of the disclosure, the voltage frequency of the direct current side of the inverter is detected in real time and compared with the frequency threshold value. To determine whether the real-time voltage frequency is a high frequency or a low frequency, and thus whether the first driving signal based on the standard sinusoidal signal needs to be modulated. The first drive signal is modulated and the inverter is controlled to operate on the modulated second drive signal, if necessary. In this manner, the modulation timing of the drive signal is identified based on the frequency threshold. The harmonic distortion degree of the output voltage of the frequency converter is reduced when the voltage frequency of the direct current side is higher and lower. And the control method is relatively simple and easy to realize.

Optionally, in step S102, the processor determines the frequency threshold by:

Under the rated working condition, the processor acquires a first frequency harmonic distortion curve of the DC side of the inverter under the first driving signal and a second frequency harmonic distortion curve under the second driving signal.

The processor takes the direct current voltage frequency corresponding to the intersection point of the first frequency harmonic distortion curve and the second frequency harmonic distortion curve as a frequency threshold.

Here, the frequency harmonic distortion curve of the ac test output voltage of the frequency converter is tested based on the first drive signal and the second drive signal, respectively. Namely a first harmonic distortion curve and a second harmonic distortion curve. Wherein the first driving signal is a driving signal based on a sinusoidal signal and the second driving signal is a modulated driving signal. Since the modulation scheme is active closed loop modulation, the first drive signal is a drive signal without closed loop, and the second drive signal is a drive signal after closed loop modulation. Further, under the first driving signal, harmonic distortion of the output voltage is low at high frequency, and harmonic distortion of the output voltage is high at low frequency. Under the second driving signal, the phase shift of the sampling circuit is increased at high frequency, so that the harmonic distortion of the output voltage is higher, and the harmonic frequency of the output voltage is lower at low frequency. Therefore, the intersection of the harmonic distortion curves under these two signals can be taken as the frequency threshold.

Optionally, in step S102, the processor determines whether modulation is required for the first driving signal of the dc side voltage of the inverter according to the real-time voltage frequency and the frequency threshold, including:

In the case that the real-time voltage frequency is less than the frequency threshold, the processor determines that the first drive signal of the inverter dc side voltage needs to be modulated.

In the case where the real-time voltage frequency is greater than or equal to the frequency threshold, the processor determines that modulation is not required for the first drive signal of the inverter dc side voltage.

Here, as described above, in the case where the dc side driving signal of the frequency converter is the first frequency signal, if the dc side real-time voltage frequency is greater than or equal to the frequency threshold value, it indicates that active closed-loop modulation is not required. If the direct current side real-time voltage frequency is less than the frequency threshold, the first driving signal is required to be subjected to active closed-loop modulation. So that the direct-current side voltage fluctuation signal and the modulated signal are partially counteracted, and the harmonic distortion of the alternating-current side voltage is ensured to be within a certain range.

Optionally, in step S103, the processor acquires the modulated second driving signal by:

s131, the processor obtains an average value of the DC side voltage of the frequency converter and an instantaneous value of the DC side voltage of the frequency converter. The voltage average value refers to an average value when the voltage fluctuation of the direct current side meets a preset condition.

And S132, the processor takes the ratio of the average voltage value to the instantaneous voltage value as a modulation coefficient.

And S133, the processor modulates the first driving signal according to the modulation coefficient to obtain a second driving signal.

Here, the modulation factor is acquired, and the first drive signal is modulated based on the modulation factor, thereby obtaining the second drive signal. Specifically, the modulation factor is obtained by calculating the average value of the dc side voltage of the frequency converter and the instantaneous value of the voltage. The average value of the voltage at the direct current side refers to the average value of the voltage when the voltage fluctuation at the direct current side meets the preset condition. The preset condition may be that the dc side voltage fluctuation range is less than or equal to a preset range (for example, the voltage fluctuation range is less than or equal to 5% of the ripple voltage). I.e. the voltage average is obtained with small dc-side voltage fluctuations. The instantaneous value of the DC side voltage is obtained when the DC side voltage fluctuates greatly or normally.

Optionally, in step S131, the processor obtains an average value of the dc side voltage of the frequency converter and an instantaneous value of the dc side voltage of the frequency converter, including:

under the condition that the driving signal of the frequency converter is turned off, the processor obtains the average value of the direct-current side voltage of the frequency converter.

Under the condition that a driving signal of the frequency converter is normally input, the processor acquires a direct-current side voltage instantaneous value of the frequency converter.

Here, the conditions for acquiring the average value of the dc-side voltage and the instantaneous value of the voltage of the inverter are defined. And under the condition that the driving signal of the frequency converter is turned off, obtaining a voltage average value. Wherein the drive signal comprises a first drive signal or other drive signal. It will be appreciated that the voltage on the dc side of the frequency converter is substantially constant and free of fluctuations after switching off the drive signal. At this time, the dc side voltage average value was sampled and recorded as V _dc-ref. In the case of normal input of the driving signal of the frequency converter, the dc side voltage fluctuates due to the instantaneous power unbalance. At this time, the sampling is performed to obtain the dc-side instantaneous voltage V _dc-ins.

Optionally, in step S134, the processor modulates the first driving signal according to the modulation factor to obtain a second driving signal, including:

the processor takes the product of the modulation factor and the first drive signal as a modulated second drive signal.

Here, since the modulation factor is a ratio of the average voltage value and the instantaneous voltage value, the product of the modulation factor and the first drive signal is used as the modulated second drive signal. In this way, the voltage fluctuation on the direct current side is offset by the voltage instantaneous value, and the standard sinusoidal voltage can be obtained on the alternating current side. Thereby greatly reducing the degree of harmonic distortion.

As shown in conjunction with fig. 3, an embodiment of the present disclosure provides another control method for a dc inverter, including:

s201, under the condition that the inverter works normally, the processor detects the voltage frequency of the direct current side of the inverter in real time.

S202, the processor judges whether the first driving signal of the DC side voltage of the inverter needs to be modulated or not according to the real-time voltage frequency and the frequency threshold value. The frequency threshold is used for identifying high and low frequencies of the direct-current side voltage, and the first driving signal is a driving signal based on a standard sinusoidal signal.

And S203, if yes, the processor acquires the modulated second driving signal and controls the inverter to work under the second driving signal.

S204, if not, the processor controls the inverter to operate under the first driving signal.

Here, if the real-time voltage frequency is greater than or equal to the frequency threshold, it is determined that the first driving signal of the dc side voltage of the inverter does not need modulation. At this time, the frequency converter is controlled to continue to work under the first driving signal. In this way, when the modulation signal is recognized as high frequency, the direct-current side voltage fluctuation is small. The first drive signal based on the standard sinusoidal signal is taken as the drive signal. At this time, the sampling circuit has a large phase shift, and if the first driving signal is modulated, THD is raised. Therefore, the first driving signal is modulated only when the frequency of the modulating signal is low. The modulated second driving signal is offset with the ac component existing on the dc side, and harmonic distortion can be reduced.

As shown in conjunction with fig. 4, an embodiment of the present disclosure provides another control method for a dc inverter, including:

S301, under the condition that the inverter works normally, the processor detects the voltage frequency of the direct current side of the inverter in real time.

S302, the processor judges whether the first driving signal of the DC side voltage of the inverter needs to be modulated or not according to the real-time voltage frequency and the frequency threshold value. The frequency threshold is used for identifying high and low frequencies of the direct-current side voltage, and the first driving signal is a driving signal based on a standard sinusoidal signal.

And S303, if so, the processor acquires the modulated second driving signal and controls the inverter to work under the second driving signal.

And S304, controlling the inverter to work under the first driving signal by the processor under the condition that the real-time voltage threshold value is larger than or equal to the frequency threshold value.

S305, if not, the processor controls the inverter to operate under the first driving signal.

Here, after the real-time voltage frequency is low and the first driving signal is modulated, the voltage frequency of the dc side needs to be detected in real time. When the voltage frequency increases to be greater than the frequency threshold value, the inverter is controlled to operate on the first drive signal, which is the drive signal before modulation. That is, when the frequency converter works, the driving signal of the frequency converter is controlled to be switched between the first driving signal and the second driving signal according to the real-time voltage frequency, so that harmonic distortion is reduced.

In some embodiments, as shown in fig. 5, the sinusoidal signal is a modulated signal. Setting the square wave signal to be 1 when the amplitude of the modulation signal is larger than y ₁; when the amplitude of the modulated signal is less than y ₂, the square wave signal is set to 0. The sine modulation signal with one period is arranged between two rising edges of the square wave signal. The comparison values y ₁ and y ₂ should be properly far from the zero crossing point so that the error caused by the jitter of the modulated signal can be greatly reduced. Meanwhile, a high-frequency clock count (clock) with a known frequency is adopted in one period, so that the frequency of the sinusoidal modulation signal can be calculated. Since the drive signal is generated by multiplying the triangular carrier on the basis of the sinusoidal signal. The frequency obtained by calculation in the above manner is the real-time voltage frequency.

As shown in conjunction with fig. 6, an embodiment of the present disclosure provides another control method for a dc inverter, including:

s401, operating an inverter;

S402, detecting the voltage frequency of the direct current side of the inverter in real time;

s403, judging whether the real-time voltage frequency is greater than or equal to a frequency threshold, if so, executing S404; otherwise, executing S410;

s404, judging that a first driving signal of the DC side voltage of the inverter needs to be modulated;

S405, under the condition that a driving signal of the frequency converter is turned off, obtaining a direct-current side voltage average value of the frequency converter;

S406, under the condition that a driving signal of the frequency converter is normally input, acquiring a DC side voltage instantaneous value of the frequency converter;

s407, taking the ratio of the average voltage value to the instantaneous voltage value as a modulation coefficient;

s408, taking the product of the modulation coefficient and the first driving signal as a modulated second driving signal;

S409, controlling the inverter to work under the modulated second driving signal; then S402 is performed;

s410, judging that the first driving signal of the DC side voltage of the inverter does not need to be modulated;

S411, the inverter is controlled to operate under the first driving signal, and then S402 is performed.

As shown in conjunction with fig. 7, an embodiment of the present disclosure provides a control apparatus 200 for a dc-dc converter, including a processor (processor) 100 and a memory (memory) 101. Optionally, the apparatus may further comprise a communication interface (Communication Interface) 102 and a bus 103. The processor 100, the communication interface 102, and the memory 101 may communicate with each other via the bus 103. The communication interface 102 may be used for information transfer. The processor 100 may call logic instructions in the memory 101 to perform the control method for a dc-inverter of the above-described embodiments.

Further, the logic instructions in the memory 101 described above may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand alone product.

The memory 101 is a computer readable storage medium that can be used to store a software program, a computer executable program, such as program instructions/modules corresponding to the methods in the embodiments of the present disclosure. The processor 100 executes functional applications and data processing by executing program instructions/modules stored in the memory 101, i.e., implements the control method for a dc-dc converter in the above-described embodiments.

The memory 101 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, at least one application program required for a function; the storage data area may store data created according to the use of the terminal device, etc. Further, the memory 101 may include a high-speed random access memory, and may also include a nonvolatile memory.

As shown in conjunction with fig. 8, an embodiment of the present disclosure provides a dc inverter 300, comprising: a dc inverter body, and the control device 200 for a dc inverter described above. The control device 200 for a dc inverter is mounted to the dc inverter body. The mounting relationships described herein are not limited to placement within a product, but include mounting connections to other components of a product, including but not limited to physical, electrical, or signal transmission connections, etc. Those skilled in the art will appreciate that the control device 200 for a dc-dc converter may be adapted to a viable product body, thereby enabling other viable embodiments.

The disclosed embodiments provide a computer-readable storage medium storing computer-executable instructions configured to perform the above-described control method for a dc-inverter.

The computer readable storage medium may be a transitory computer readable storage medium or a non-transitory computer readable storage medium.

Embodiments of the present disclosure may be embodied in a software product stored on a storage medium, including one or more instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of a method according to embodiments of the present disclosure. And the aforementioned storage medium may be a non-transitory storage medium including: a plurality of media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or a transitory storage medium.

The above description and the drawings illustrate embodiments of the disclosure sufficiently to enable those skilled in the art to practice them. Other embodiments may involve structural, logical, electrical, process, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of others. Moreover, the terminology used in the present application is for the purpose of describing embodiments only and is not intended to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a," "an," and "the" (the) are intended to include the plural forms as well, unless the context clearly indicates otherwise. Similarly, the term "and/or" as used in this disclosure is meant to encompass any and all possible combinations of one or more of the associated listed. Furthermore, when used in the present disclosure, the terms "comprises," "comprising," and/or variations thereof, mean that the recited features, integers, steps, operations, elements, and/or components are present, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Without further limitation, an element defined by the phrase "comprising one …" does not exclude the presence of other like elements in a process, method or apparatus that includes the element. In this context, each embodiment may be described with emphasis on the differences from the other embodiments, and the same similar parts between the various embodiments may be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method sections disclosed in the embodiments, the description of the method sections may be referred to for relevance.

Those of skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. The skilled artisan may use different methods for each particular application to achieve the described functionality, but such implementation should not be considered to be beyond the scope of the embodiments of the present disclosure. It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.

In the embodiments disclosed herein, the disclosed methods, articles of manufacture (including but not limited to devices, apparatuses, etc.) may be practiced in other ways. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the units may be merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form. The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to implement the present embodiment. In addition, each functional unit in the embodiments of the present disclosure may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. In the description corresponding to the flowcharts and block diagrams in the figures, operations or steps corresponding to different blocks may also occur in different orders than that disclosed in the description, and sometimes no specific order exists between different operations or steps. For example, two consecutive operations or steps may actually be performed substantially in parallel, they may sometimes be performed in reverse order, which may be dependent on the functions involved. Each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Claims (10)

1. A control method for a dc inverter, comprising:

under the condition that the inverter works normally, detecting the voltage frequency of the direct current side of the inverter in real time;

Judging whether a first driving signal of the DC side voltage of the inverter needs to be modulated or not according to the real-time voltage frequency and the frequency threshold value; the frequency threshold is used for identifying high and low frequencies of direct-current side voltage, and the first driving signal is a driving signal based on a standard sinusoidal signal;

and if so, acquiring a modulated second driving signal and controlling the inverter to work under the second driving signal.

2. The method of claim 1, wherein the frequency threshold is determined by:

under the rated working condition, a first frequency harmonic distortion curve of the direct current side of the inverter under a first driving signal and a second frequency harmonic distortion curve of the direct current side of the inverter under a second driving signal are obtained;

and taking the direct current voltage frequency corresponding to the intersection point of the first frequency harmonic distortion curve and the second frequency harmonic distortion curve as a frequency threshold.

3. The method of claim 1, wherein determining whether the first drive signal of the inverter dc side voltage requires modulation comprises:

Under the condition that the frequency of the real-time voltage is smaller than a frequency threshold value, judging that a first driving signal of the voltage of the direct current side of the inverter needs to be modulated;

and under the condition that the frequency of the real-time voltage is greater than or equal to a frequency threshold value, judging that the first driving signal of the DC side voltage of the inverter does not need to be modulated.

4. The method of claim 1, wherein the modulated second drive signal is obtained by:

obtaining a DC side voltage average value and a voltage instantaneous value of the frequency converter; the voltage average value refers to an average value when the voltage fluctuation of the direct current side accords with a preset condition;

Taking the ratio of the voltage average value to the voltage instantaneous value as a modulation coefficient;

The first drive signal is modulated according to the modulation factor to obtain a second drive signal.

5. The method of claim 4, wherein modulating the first drive signal to obtain the second drive signal according to the modulation factor comprises:

taking the product of the modulation factor and the first driving signal as the adjusted second driving signal.

6. The method according to any one of claims 1 to 5, further comprising:

and if not, controlling the inverter to work under the first driving signal.

7. The method of any one of claims 1 to 5, wherein said controlling said inverter to operate under a modulated second drive signal further comprises:

And controlling the inverter to work under a first driving signal under the condition that the frequency of the modulated real-time voltage is larger than or equal to a frequency threshold value.

8. A control device for a dc-inverter comprising a processor and a memory storing program instructions, characterized in that the processor is configured to execute the control method for a dc-inverter according to any of claims 1 to 7 when running the program instructions.

9. A dc inverter, comprising:

a DC inverter body;

the control device for a dc inverter according to claim 8, mounted to the dc inverter body.

10. A storage medium storing program instructions which, when executed, perform the control method for a dc-inverter according to any one of claims 1 to 7.