CN117650712B

CN117650712B - Control method and controller for ANPC (advanced personal computer) type three-level converter

Info

Publication number: CN117650712B
Application number: CN202410117211.7A
Authority: CN
Inventors: 王宁宁; 仇成丰; 王振存; 潘逸菎; 刘欣; 熊启国
Original assignee: Shuangyili Ningbo Battery Co ltd
Current assignee: Shuangyili Ningbo Battery Co ltd
Priority date: 2024-01-29
Filing date: 2024-01-29
Publication date: 2024-05-03
Anticipated expiration: 2044-01-29
Also published as: CN117650712A

Abstract

The embodiment of the application relates to the technical field of power electronics, and provides a control method and a controller of an ANPC (automatic network programmable logic controller) type three-level converter, wherein the control method comprises the steps of determining the fluctuation trend of a neutral point voltage compacting value according to the acquired neutral point voltage compacting value and a preset neutral point voltage value on a direct current bus; determining modulation waves of each phase according to the fluctuation trend of the neutral-point voltage compacting value; determining driving signals of each phase and driving complementary signals of each phase according to the modulated wave, the upper carrier wave and the lower carrier wave of each phase; and controlling the switching tube of each phase according to the driving signal of each phase and the driving complementary signal of each phase. The application has the effects of midpoint voltage control and lower switching loss in the full power factor range.

Description

Control method and controller for ANPC (advanced personal computer) type three-level converter

Technical Field

The application relates to the field of power electronics, in particular to a control method and a controller of an ANPC type three-level converter.

Background

Compared with an NPC type converter, the existing ANPC type three-level converter can generate a redundant zero-voltage state by using a fully-controlled device instead of a clamping diode, and the loss distribution of a power device can be adjusted by reasonably switching the redundant zero-voltage state in the circulation process, so that the balance of junction temperature is realized.

In the related art, an ANPC type three-level converter is controlled, and a driving signal of a switching tube is generally obtained by single-modulation wave carrier modulation or double-modulation wave carrier modulation. However, shan Diaozhi wave carrier modulation is limited by a system power factor and a modulation degree, and the waveform fluctuation of the direct current bus can be restrained only in a certain range; the double-modulation wave carrier modulation can restrain low-frequency fluctuation of midpoint voltage in a full power factor range, but the switching frequency of the double-modulation wave carrier modulation is 4/3 times of that of the single-modulation wave carrier modulation, so that the loss of a switching tube is increased, and the efficiency is reduced.

However, the inventor has realized that in practical use, it is desirable to combine the advantages of two modulation strategies in the same ANPC type three-level converter, and if the control method in the related art is used, the complementary logic between the driving signals needs to be modified, and to implement the control logic of the changed driving signals, the hardware structure in the ANPC type three-level converter needs to be correspondingly modified, which is complex in operation and high in replacement cost.

Disclosure of Invention

One or more embodiments of the present application provide a control method and a controller for an ANPC-type three-level converter, so as to solve or at least partially alleviate the problem in the related art that two modulation strategies are compatible on the same ANPC-type three-level converter, and the operation is complex and the cost of the alternation is higher.

In a first aspect of the present application, an ANPC three-level converter control method is provided, which adopts the following technical scheme:

the ANPC type three-level converter control method comprises the following steps:

and determining the fluctuation trend of the neutral point voltage compacting value according to the acquired neutral point voltage compacting value and a preset neutral point voltage value on the direct current bus, wherein the neutral point voltage compacting value is the voltage value of the direct current bus in an ANPC three-level circuit in the ANPC three-level converter.

And determining the modulation wave of each phase according to the fluctuation trend of the neutral point voltage compacting value.

And determining driving signals of each phase and driving complementary signals of each phase according to the modulated wave, the upper carrier wave and the lower carrier wave of each phase.

And controlling switching tubes of each phase on the ANPC three-level circuit according to the driving signals of each phase and the driving complementary signals of each phase.

By adopting the technical scheme, the midpoint voltage on the direct current bus is monitored in real time by acquiring the midpoint voltage compacting value and the preset midpoint voltage value on the direct current bus, and the fluctuation trend of the midpoint voltage compacting value is determined; the preset midpoint voltage value is a theoretical value calculated in an ideal state of no voltage fluctuation of the converter, and the fluctuation condition of the midpoint voltage compacting time value is judged by taking the preset midpoint voltage value as a reference; when the fluctuation of the midpoint voltage is smaller, a single modulation wave modulation strategy can be adopted to inhibit the fluctuation of the midpoint voltage, when the fluctuation of the midpoint voltage is larger, the single modulation wave modulation strategy cannot play a good role in inhibiting the fluctuation of the midpoint voltage, and at the moment, the modulation strategy is switched, and the double modulation wave modulation strategy is adopted to inhibit the low-frequency fluctuation of the midpoint voltage in the full power factor range, so that the modulation waves of each phase can be determined according to the fluctuation condition of the midpoint voltage compact value.

Obtaining driving signals of each phase and driving complementary signals of each phase according to the modulated wave, the upper carrier wave and the lower carrier wave of each phase; according to the driving signals of each phase and the driving complementary signals of each phase, the switching tubes of each phase on the ANPC three-level circuit are controlled, two switching tubes on the same bridge arm are guaranteed not to be simultaneously turned on, the state that the two switching tubes are alternately turned on is achieved, the continuous conduction time of a single switching tube is reduced, and the loss of the switching tubes is reduced. When the middle-point voltage compact value is reduced from larger fluctuation to smaller fluctuation, the control strategy can be switched to the single-modulation strategy again, at the moment, the switching frequency of the switching tube is reduced, the loss of the switching tube is reduced, the switching tube can dissipate heat in time, and the probability of damage and faults of the switching tube is reduced. The method does not need to change the hardware structure inside the converter, and simultaneously considers two modulation strategies in one converter under the condition of keeping the complementary logic of the driving signal, thereby realizing midpoint voltage control and lower switching loss in the full power factor range.

In one embodiment, the determining the modulation wave of each phase according to the fluctuation trend of the neutral point voltage compacting value comprises:

and determining a corresponding zero sequence component and a modulation strategy according to the fluctuation trend.

And determining the modulation wave of each phase according to the determined modulation strategy, the corresponding zero sequence component and the initial modulation wave of each phase.

In one embodiment, the corresponding zero sequence component and modulation strategy are determined according to the fluctuation trend; determining the modulation wave of each phase according to the determined modulation strategy, the corresponding zero sequence component and the initial modulation wave of each phase comprises:

And under the condition that the fluctuation value of the neutral voltage value relative to the preset neutral voltage value is smaller than the preset fluctuation value, determining single modulation waves of each phase according to the first zero sequence component and the initial modulation waves of each phase, wherein the single modulation waves comprise an upper modulation wave and a lower modulation wave.

And under the condition that the fluctuation value is larger than or equal to the preset fluctuation value, determining double modulation waves of each phase according to the first zero sequence component, the second zero sequence component and the initial modulation waves of each phase, wherein the double modulation waves comprise an upper modulation wave and a lower modulation wave.

In one embodiment, the determining the driving signal of each phase and the driving complementary signal of each phase according to the modulated wave, the upper carrier wave and the lower carrier wave of each phase includes:

And comparing the upper modulation wave and the upper carrier wave of each phase to obtain an upper driving signal and an upper driving complementary signal of the corresponding phase.

And comparing the lower modulation wave and the lower carrier wave of each phase to obtain a lower driving signal and a lower driving complementary signal of the corresponding phase.

And under the condition that the initial modulation wave is larger than zero, comparing the lower modulation wave of each phase with the lower carrier wave to obtain a middle driving signal and a middle driving complementary signal of the corresponding phase.

And under the condition that the initial modulation wave is smaller than zero, comparing the upper modulation wave of each phase with the upper carrier wave to obtain the middle driving signal and the middle driving complementary signal of the corresponding phase.

In one embodiment, at least part of the phases of the ANPC three-level circuit include an upper bridge arm, a middle bridge arm and a lower bridge arm, the upper bridge arm includes a first switching tube and a fifth switching tube, the middle bridge arm includes a second switching tube and a third switching tube, and the lower bridge arm includes a fourth switching tube and a sixth switching tube.

The switching tube for controlling each phase on the ANPC three-level circuit according to the driving signal of each phase and the driving complementary signal of each phase comprises:

And controlling the first switching tube in the upper bridge arm according to the upper driving signal.

And controlling the fifth switching tube in the upper bridge arm according to the upper driving complementary signal.

And controlling the second switching tube in the middle bridge arm according to the middle driving signal.

And controlling the third switching tube in the middle bridge arm according to the middle driving complementary signal.

And controlling the fourth switching tube in the lower bridge arm according to the lower driving signal.

And controlling the sixth switching tube in the lower bridge arm according to the lower driving complementary signal.

In one embodiment, before determining the corresponding zero sequence component and modulation strategy according to the fluctuation trend, the method further includes:

and determining a zero sequence component according to the initial modulation wave.

And determining an upper carrier and a lower carrier according to the principle of double-carrier up-down lamination.

In one embodiment, said determining a zero sequence component from said initial modulated wave comprises:

And obtaining an initial modulation wave maximum value and an initial modulation wave minimum value according to the initial modulation wave.

The first zero sequence component is。

The second zero sequence component is。

Wherein,For the initial modulation wave maximum,/>Is the initial modulation wave minimum.

In one embodiment, when the fluctuation value of the midpoint voltage value relative to the preset midpoint voltage value is smaller than a preset fluctuation value, determining the single modulation wave of each phase according to the first zero sequence component and the initial modulation wave of each phase includes:

The upper modulation wave of the single modulation wave is ，/>。

The lower modulation wave of the single modulation wave is，/>。

Wherein,For the initial modulation wave,/>For the first zero sequence component, x represents x phase, and a, b and c represent a phase, b phase and c phase respectively in the ANPC three-level circuit.

In one embodiment, when the fluctuation value is greater than or equal to the preset fluctuation value, determining the dual modulation wave of each phase according to the first zero sequence component, the second zero sequence component and the initial modulation wave of each phase includes:

the upper modulation wave of the double modulation wave is ，/>。

The lower modulation wave of the double modulation wave is，/>。

Wherein,For the initial modulation wave,/>For the first zero sequence component,/>For the second zero sequence component, x represents x phase, and a, b and c represent a phase, b phase and c phase respectively in the ANPC three-level circuit.

And obtaining the distance from the initial modulation wave to the preset boundary according to the initial modulation wave and the preset boundary, wherein the distance from the initial modulation wave to the preset boundary comprises an upper boundary distance and a lower boundary distance.

And determining the first zero sequence component according to the upper boundary distance and the lower boundary distance.

And determining the second zero sequence component according to the maximum value of the initial modulation wave and the minimum value of the initial modulation wave.

In one embodiment, the obtaining, according to the initial modulation wave and a preset boundary, a distance from the initial modulation wave to the preset boundary includes:

The upper boundary distance is ，/>。

The lower boundary distance is，/>。

Wherein,For the initial modulated wave, x represents the x-phase, and a, b and c represent the a-phase, b-phase and c-phase, respectively, in the ANPC three-level circuit.

The upper boundary distance And the lower boundary distance/>Respectively/>，/>。

In one embodiment, said determining said first zero sequence component from said upper boundary distance and said lower boundary distance comprises:

The first zero sequence component is Wherein/>For the upper boundary distance,/>Is the lower boundary distance, and when/>Get/>Time,/>The sign of (2) is positive, when/>Get/>Time,/>Is negative in sign.

The upper modulation wave of the single modulation wave is ，/>。

The lower modulation wave of the single modulation wave is，/>。

In a second aspect of the present application, a controller is provided, which adopts the following technical scheme:

A controller comprising a memory, a processor and a computer program stored in the memory and executable on the processor, which when executed by the processor implements an ANPC-type three-level converter control method as described above.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following brief description will be given to the accompanying drawings of the embodiments, and it is apparent that the accompanying drawings in the following description relate only to some embodiments of the present application, not to limit the present application.

Fig. 1 is a schematic diagram of a one-phase bridge arm of an ANPC three-level circuit in an ANPC three-level converter in the related art.

Fig. 2 is a flow chart of a control method of an ANPC type three-level converter according to some embodiments of the present application.

Fig. 3 is a schematic diagram of a driving signal generation flow according to some embodiments of the present application.

Fig. 4 is a schematic diagram of signal waveforms generated using a first single modulation wave correspondence according to some embodiments of the present application.

Fig. 5 is an enlarged schematic view of the portion a in fig. 4.

Fig. 6 is a schematic diagram of signal waveforms generated using dual modulation wave correspondence according to some embodiments of the present application.

Fig. 7 is a schematic diagram of signal waveforms generated using a second single modulation wave correspondence in accordance with some embodiments of the present application.

Fig. 8 is a schematic diagram of signal waveforms generated using a third single modulation wave correspondence in accordance with some embodiments of the present application.

Fig. 9 is a schematic structural diagram of a controller according to some embodiments of the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings showing various embodiments according to the present application, and it should be understood that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art without undue burden on the person of ordinary skill in the art based on the embodiments described herein, are intended to be within the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising," "including," "having," "containing," and the like in the description of the present application and in the claims and drawings are used for open ended terms. Thus, a method or apparatus that "comprises," includes, "" has "or" has, for example, one or more steps or elements, but is not limited to having only the one or more elements. The terms first, second and the like in the description and in the claims or in the above-described figures, are used for distinguishing between different objects and not necessarily for describing a particular sequential or chronological order. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present application, it should be noted that, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "attached" are to be construed broadly, and may be, for example, directly connected or indirectly connected through an intermediary, or may be in communication with the interior of two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the described embodiments of the application may be combined with other embodiments.

As noted above, it should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The terms "a" and "an" in this specification may mean one, but may also be consistent with the meaning of "at least one" or "one or more". The term "about" generally means that the value mentioned is plus or minus 10%, or more specifically plus or minus 5%. The term "or" as used in the claims means "and/or" unless explicitly indicated to the contrary, only alternatives are indicated.

The term "and/or" in the present application is merely an association relation describing the association object, and indicates that three kinds of relations may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In the present application, the character "/" generally indicates that the front and rear related objects are an or relationship.

Fig. 1 is a schematic structural diagram of an ANPC three-level circuit-phase bridge arm in an ANPC three-level converter in the related art, the ANPC three-level circuit includes three phases, which are an a phase, a b phase and a C phase, the three phases are the same, only the a-phase bridge arm structure is shown in fig. 1, each phase includes an upper bridge arm, a middle bridge arm, a lower bridge arm, a first capacitor C1 and a second capacitor C2, one end of the first capacitor C1 is connected with one end of the second capacitor C2, a connection point of the first capacitor C1 and the second capacitor C2 is a midpoint O of a direct current bus, one end of the upper bridge arm is connected with one end of a lower bridge arm, a connection point O of the first bridge arm and the second bridge arm is a first connection point, the other end of the upper bridge arm is connected with the other end of the first capacitor C1, the other end of the lower bridge arm is connected with the other end of the second capacitor C2, one end of the upper bridge arm, the lower bridge arm and the middle bridge arm includes two switching tubes, one end of the upper bridge arm and the lower bridge arm is connected with one end of the corresponding switching tubes, and the other end of the two switching tubes are connected between the two corresponding connection points of the two switching tubes. The upper bridge arm comprises a first switching tube S1 and a fifth switching tube S5, the middle bridge arm comprises a second switching tube S2 and a third switching tube S3, and the lower bridge arm comprises a fourth switching tube S4 and a sixth switching tube S6.

One or more embodiments of the present application disclose an ANPC type three-level converter control method. Referring to fig. 2, the anpc type three-level converter control method includes:

S1: and determining the fluctuation trend of the neutral point voltage compacting value according to the acquired neutral point voltage compacting value and a preset neutral point voltage value on the direct current bus, wherein the neutral point voltage compacting value is the neutral point voltage compacting value on the direct current bus in an ANPC three-level circuit in the ANPC three-level converter. And acquiring a midpoint voltage compacting value at a midpoint of the direct current bus in real time so as to monitor the fluctuation condition of midpoint voltage, and switching different control strategies according to the fluctuation condition of midpoint voltage.

S2: determining modulation waves of each phase according to the fluctuation trend of the neutral-point voltage compacting value;

Specifically, as can be seen from fig. 1, the voltage on the first capacitor C1 is the first voltage V1, the voltage on the second capacitor C2 is the second voltage V2, and ideally, the three-phase voltage of the ANPC type three-level converter has no fluctuation, the preset midpoint voltage value of each phase is (v1+v2)/2, and the fluctuation condition of the midpoint voltage compacting value is analyzed based on the preset midpoint voltage value. The fluctuation condition of the neutral point voltage compacting value can be the amplitude of up-and-down oscillation around a preset neutral point voltage value, the speed of the neutral point voltage real-time value relative to the increasing trend or the decreasing trend of the neutral point voltage compacting value, the distance of the neutral point voltage real-time value from the neutral point voltage compacting value and the like, when the oscillation amplitude of the neutral point voltage compacting value is overlarge, the increasing trend or the decreasing trend is overlarge, or the deviation distance is overlarge, double modulation waves can be generated, when the oscillation amplitude of the neutral point voltage compacting value is smaller, the increasing trend or the decreasing trend is slower, or the deviation distance is not great, shan Diaozhi waves can be generated, and different modulation waves are generated according to the fluctuation condition of the neutral point voltage compacting value.

S3: and determining driving signals of each phase and driving complementary signals of each phase according to the modulated wave, the upper carrier wave and the lower carrier wave of each phase. Specifically, for example, the modulated waves of each phase may be divided into an upper carrier and a lower carrier, the upper modulated waves are compared with the upper carrier to obtain an upper driving signal, and an upper driving complementary signal is obtained according to the upper driving signal, the driving signal and the driving complementary signal are complementary, and are a group of control signals for controlling two switching tubes on the same bridge arm, and the upper driving signal and the upper driving complementary signal are used for controlling two switching tubes in the upper bridge arm.

S4: and controlling switching tubes of each phase on the ANPC three-level circuit according to the driving signals of each phase and the driving complementary signals of each phase. Specifically, for example, the upper driving signal and the upper driving complementary signal control the first switching tube and the fifth switching tube in the upper bridge arm, so that two switching tubes on the same bridge arm cannot be turned on simultaneously, and the state that the two switching tubes are turned on alternately is realized.

Acquiring a neutral point voltage compacting value and a preset neutral point voltage value on a direct current bus through acquisition, and monitoring the neutral point voltage on the direct current bus in real time to determine the fluctuation trend of the neutral point voltage compacting value; the preset midpoint voltage value is a theoretical value calculated in an ideal state of no voltage fluctuation of the converter, and the fluctuation condition of the midpoint voltage compacting time value is judged by taking the preset midpoint voltage value as a reference; when the fluctuation of the midpoint voltage is smaller, a single modulation wave modulation strategy can be adopted to inhibit the fluctuation of the midpoint voltage, when the fluctuation of the midpoint voltage is larger, the single modulation wave modulation strategy cannot play a good role in inhibiting the fluctuation of the midpoint voltage, and at the moment, the modulation strategy is switched, and the double modulation wave modulation strategy is adopted to inhibit the low-frequency fluctuation of the midpoint voltage in the full power factor range, so that the modulation waves of each phase can be determined according to the fluctuation condition of the midpoint voltage compact value.

In some embodiments, said determining the modulation wave for each phase based on the trend of the fluctuation of the midpoint voltage compact value comprises:

Specifically, as described above, the fluctuation condition of the neutral voltage compacting value may be the amplitude of the up-and-down oscillation around the preset neutral voltage value, the speed of the neutral voltage real-time value relative to the increasing trend or the decreasing trend of the neutral voltage compacting value, the distance of the neutral voltage real-time value from the neutral voltage compacting value, and the like. When the oscillation amplitude of the middle-point voltage compacting time value is too large, the increasing trend or the decreasing trend is too fast, the deviation distance is too large, and the like, a double-modulation wave modulation strategy can be selected, and the zero sequence component adopted by the double-modulation wave modulation strategy is determined; when the oscillation amplitude of the middle-point voltage compacting time value is smaller, the increasing trend or the decreasing trend is slower, the deviation distance is not large, and the like, a single modulation wave modulation strategy can be selected, and the zero sequence component adopted by the single modulation wave modulation strategy can be determined.

Specifically, when the modulation strategies are different, the modulation waves of each phase generated according to the corresponding zero-sequence component and the initial modulation wave transformation are also different, for example, under Shan Diaozhi wave modulation strategies, the generated single modulation wave is formed by dividing one continuous initial modulation wave after shifting the corresponding zero-sequence component; however, under the dual-modulation-wave modulation strategy, the generated dual modulation wave is two different modulation waves formed after the initial modulation wave is respectively offset by different zero sequence components. Different modulation strategies are suitable for different fluctuation trends of the neutral voltage compacting value, so that the ANPC three-level circuit can realize two modulation strategies, namely the neutral voltage control in the full power factor range is realized, and the switching loss is lower.

In some embodiments, the determining a corresponding zero sequence component and modulation strategy according to the fluctuation trend; determining the modulation wave of each phase according to the determined modulation strategy, the corresponding zero sequence component and the initial modulation wave of each phase comprises:

And analyzing the fluctuation value of the neutral point voltage compacting value relative to the preset neutral point voltage value.

Specifically, a fluctuation condition of the neutral voltage compacting value is analyzed by taking a preset neutral voltage value as a reference, wherein the fluctuation value is an absolute value of the neutral voltage compacting value deviated from the preset neutral voltage value.

And judging whether the fluctuation value is larger than or equal to a preset fluctuation value.

And when the fluctuation value is smaller than a preset fluctuation value, determining single modulation waves of each phase according to the first zero sequence component and the initial modulation waves of each phase, wherein the single modulation waves comprise upper modulation waves and lower modulation waves.

Specifically, the preset fluctuation value can be set to be 10V, when the fluctuation value is smaller than the preset fluctuation value, the fact that the fluctuation of the midpoint voltage real-time value is smaller at the moment is indicated, the midpoint voltage fluctuation suppression can be achieved by adopting a single modulation wave modulation strategy, the switching frequency of a switching tube in the circuit is not high, the loss of the switching tube is smaller, the upper modulation wave and the lower modulation wave of the single modulation wave are analyzed, and therefore a driving signal is determined according to Shan Diaozhi waves.

Specifically, when the fluctuation value is greater than or equal to a preset fluctuation value, it is indicated that the fluctuation of the midpoint voltage is greater in real time at this time, an upper modulation wave and a lower modulation wave of a single modulation wave are adopted to determine a driving signal, the suppression effect on the fluctuation of the midpoint voltage is not ideal, at this time, a modulation strategy needs to be replaced, a dual modulation wave modulation strategy is selected, and the driving signal is determined according to the upper modulation wave and the lower modulation wave of the dual modulation wave, at this time, although the switching frequency of a switching tube is increased, the switching tube loss is increased, the dual modulation wave modulation strategy has a good suppression effect on the fluctuation of the midpoint voltage, and can realize that the fluctuation of the midpoint voltage is suppressed in a full power factor range, when the fluctuation value of the midpoint voltage is reduced to be smaller than the preset fluctuation value, the control strategy is switched to a single modulation wave modulation strategy again, at this time, the switching frequency of the switching tube is reduced, the switching tube loss can radiate heat timely, and the probability of damage and faults of the switching tube is reduced.

In this embodiment, when the fluctuation value is smaller than the preset fluctuation value, it is indicated that the fluctuation of the midpoint voltage is smaller at this time, and a single modulation wave modulation strategy may be adopted to suppress the fluctuation of the midpoint voltage, and according to the first zero sequence component and the initial modulation wave of each phase, a single modulation wave of each phase is determined, where the single modulation wave includes an upper modulation wave and a lower modulation wave; when the fluctuation value is larger than or equal to a preset fluctuation value, the fact that the fluctuation of the midpoint voltage is larger at the moment is indicated, a single modulation wave modulation strategy cannot play a good role in inhibiting the fluctuation of the midpoint voltage, at the moment, the modulation strategy is switched, a double modulation wave modulation strategy is adopted, and double modulation waves of each phase are determined according to the first zero sequence component, the second zero sequence component and initial modulation waves of each phase, wherein the double modulation waves comprise upper modulation waves and lower modulation waves; the low-frequency fluctuation of the midpoint voltage is restrained in the full power factor range. When the fluctuation value of the midpoint voltage is reduced from high to less than a preset fluctuation value, the control strategy is switched to a single modulation strategy again, at the moment, the switching frequency of the switching tube is reduced, the loss of the switching tube is reduced, the switching tube can dissipate heat in time, and the probability of damage and faults of the switching tube is reduced.

In some embodiments, as shown in fig. 3, determining the driving signal for each phase and the driving complementary signal for each phase according to the modulated wave, the upper carrier, and the lower carrier for each phase includes:

S30: and comparing the upper modulation wave and the upper carrier wave of each phase to obtain an upper driving signal and an upper driving complementary signal of the corresponding phase.

S31: and comparing the lower modulation wave and the lower carrier wave of each phase to obtain a lower driving signal and a lower driving complementary signal of the corresponding phase.

S32: and judging whether the initial modulation wave is larger than zero.

S33: and under the condition that the initial modulation wave is larger than zero, comparing the lower modulation wave of each phase with the lower carrier wave to obtain a middle driving signal and a middle driving complementary signal of the corresponding phase.

S34: and under the condition that the initial modulation wave is smaller than zero, comparing the upper modulation wave of each phase with the upper carrier wave to obtain the middle driving signal and the middle driving complementary signal of the corresponding phase, wherein the driving signals comprise the upper driving signal, the lower driving signal and the middle driving signal, and the driving complementary signals comprise the upper driving complementary signal, the lower driving complementary signal and the middle driving complementary signal.

In at least one embodiment, the modulated wave is in a band above the carrier wave, corresponding to an output high level; the modulated wave is in a band below the carrier wave, corresponding to the output low level. By comparing the up/down modulated wave with the up/down carrier wave, a corresponding drive signal and drive complementary signal are generated. In addition, for the generation of the intermediate drive signal, it is necessary to output the initial modulation wave of different sizes in a segmented manner according to the size of the initial modulation wave, and the modulation wave and the carrier wave used are different, so that the final drive signal is output. The complementary control of the three bridge arms is realized by respectively outputting the driving signals of the three bridge arms.

In some embodiments, the controlling the switching tube of each phase on the ANPC tri-level circuit according to the driving signal of each phase and the driving complementary signal of each phase comprises:

And controlling the first switching tube in the upper bridge arm according to the upper driving signal. And controlling the fifth switching tube in the upper bridge arm according to the upper driving complementary signal. And controlling the second switching tube in the middle bridge arm according to the middle driving signal. And controlling the third switching tube in the middle bridge arm according to the middle driving complementary signal. And controlling the fourth switching tube in the lower bridge arm according to the lower driving signal. And controlling the sixth switching tube in the lower bridge arm according to the lower driving complementary signal.

In at least one embodiment, a schematic diagram of signal waveforms generated using a single modulation wave is shown in fig. 4, where the waveforms of the driving signals of six switching transistors are shown. As can be seen from the figure, the driving signal of the first switching tube S1 is complementary to the driving signal of the switching tube S5, and if the driving signal of the first switching tube S1 is referred to as an upper driving signal, the driving signal of the fifth switching tube S5 may be referred to as an upper driving complementary signal accordingly. Similarly, it can be seen that the driving signals of the second switching tube S2 and the third switching tube S3 are complementary, the driving signals of the fourth switching tube S4 and the sixth switching tube S6 are complementary, the complementary driving signals can ensure that two switching tubes in the same bridge arm are not conducted simultaneously, the two switching tubes are conducted alternately, the conduction time of a single switching tube is reduced, and the single switching tube can dissipate heat in time. In addition, in fig. 4, the thicker black solid line is a black solid line formed by aggregating waveforms together due to the smaller unit distance of the abscissa, and the enlarged waveform is similar to the waveform shown in fig. 5, and the specific waveform may be a regular waveform with regular distribution of high and low levels as shown in fig. 5, or an irregular waveform with unequal interval and duration between high and low levels.

In some embodiments, before determining the corresponding zero sequence component and modulation strategy according to the fluctuation trend, the method further includes:

In at least one embodiment, the initial modulation carrier wave can be selected from sine modulation wave, and three-phase sine modulation wave isWherein/>For modulation ratio, ωt is fundamental angular frequency,/>、/>And/>The sine modulated waves of a phase, b phase and c phase are respectively represented, and the phase difference of any two-phase modulated wave is 120 degrees according to the expression.

And determining an upper carrier and a lower carrier according to the principle of double-carrier up-down lamination. The principle of stacking dual carriers vertically is that one carrier is shifted vertically along the ordinate to form the other carrier, and the two carriers are called dual carriers, so that the frequencies of the two carriers in the dual carriers are the same.

In some embodiments, said determining a zero sequence component from said initial modulated wave comprises:

The first zero sequence component is; The second zero sequence component is; Wherein/>For the initial modulation wave maximum,/>Is the initial modulation wave minimum.

Under the condition that the fluctuation value of the neutral point voltage value relative to the preset neutral point voltage value is smaller than the preset fluctuation value, determining the single modulation wave of each phase according to the first zero sequence component and the initial modulation wave of each phase comprises the following steps:

The upper modulation wave of the single modulation wave is ，/>。

The lower modulation wave of the single modulation wave is，/>。

In at least one embodiment, the driving signal formed according to the above single modulation wave is shown in fig. 4, and the driving signal and the driving complementary signal formed are used to control the switching tube, so that a good effect of inhibiting the fluctuation of the midpoint voltage can be formed, the second switching tube and the third switching tube control the overall on-off of the upper bridge arm and the lower bridge arm, the first switching tube and the fifth switching tube control the on-off of the upper bridge arm, the fourth switching tube and the sixth switching tube control the on-off of the lower bridge arm, and as can be seen from fig. 4, the switching frequency of the second switching tube and the third switching tube is lower, and further the on-off switching frequency of the upper bridge arm and the lower bridge arm is relatively lower, so that the electric energy with higher quality is obtained from the ac output end. The Shan Diaozhi wave modulation strategy has low switching tube frequency, high output current electric energy quality, large space for transforming other modulation modes and rapid change of injected zero sequence components, thereby realizing different control requirements.

In some embodiments, the determining the dual modulation wave of each phase according to the first zero sequence component, the second zero sequence component, and the initial modulation wave of each phase when the fluctuation value is greater than or equal to the preset fluctuation value includes:

the upper modulation wave of the double modulation wave is ，/>。

The lower modulation wave of the double modulation wave is，/>。

Wherein,For the initial modulation wave,/>For the first zero sequence component,/>For the second zero sequence component, x represents x phase, and a, b and c represent a phase, b phase and c phase respectively in the ANPC three-level circuit. /(I)

In at least one embodiment, the driving signal generated using the above-described dual modulation wave, as shown in fig. 6, achieves suppression of mid-point voltage low frequency fluctuations over the full power factor range. As can be seen from the waveform, the switching frequency of the second switching tube and the third switching tube is lower, so that the electric energy with higher quality is obtained from the ac output end.

In at least one embodiment, the initial modulation carrier wave can be selected from sine modulation wave, and three-phase sine modulation wave isWherein/>For modulation ratio, ωt is fundamental angular frequency,/>、/>And/>The sine modulated waves of a phase, b phase and c phase are respectively represented, and the phase difference of any two-phase modulated wave is 120 degrees according to the expression. The preset boundary may be set to ±1, wherein the upper boundary is 1 and the lower boundary is-1.

In some embodiments, the obtaining the distance from the initial modulation wave to the preset boundary according to the initial modulation wave and the preset boundary includes:

The upper boundary distance is ，/>。

The lower boundary distance is，/>。

Said determining said first zero sequence component from said upper boundary distance and said lower boundary distance comprises:

In some embodiments, in a case where the fluctuation value of the midpoint voltage value relative to the preset midpoint voltage value is smaller than a preset fluctuation value, determining a single modulation wave for each phase from the first zero sequence component and the initial modulation wave for each phase includes:

The upper modulation wave of the single modulation wave is ，/>。

The lower modulation wave of the single modulation wave is，/>。

Wherein,For the initial modulation wave,/>For the first zero sequence component, x represents x phase, and a, b and c represent a phase, b phase and c phase respectively in the ANPC three-level circuit. /(I)

In at least one embodiment, waveforms of a driving signal and a driving complementary signal obtained by adopting the single modulation wave are shown in fig. 7, compared with fig. 4, in fig. 7, control switching frequencies of the second switching tube and the third switching tube are unchanged, but control switching frequencies of the first switching tube and the fifth switching tube, and control switching frequencies of the fourth switching tube and the sixth switching tube are increased, on one hand, on-off time of the switching tube is shortened, on-off loss of the switching tube is reduced, and therefore efficiency of a circuit is improved; on the other hand, the switching frequency of the switching tube is increased, the switching loss of the switching tube is also increased, and the harmonic wave in the output waveform is increased, so that the output waveform may be distorted, and the quality of electric energy output is reduced. Therefore, the driving signal generated by the single modulation wave used in fig. 7 can improve the efficiency of the circuit to a certain extent compared with the driving signal generated by the single modulation wave used in fig. 4, but correspondingly, the power quality of the circuit output can also be reduced.

The upper modulation wave of the single modulation wave is ，/>。

The lower modulation wave of the single modulation wave is，/>。

In at least one embodiment, waveforms of a driving signal and a driving complementary signal obtained by adopting the single modulation wave are shown in fig. 8, compared with fig. 7, fig. 8 is obvious in that the control switching frequency of the second switching tube and the third switching tube is increased, and the control switching frequency of the first switching tube and the fifth switching tube is also increased, so that the on-off state changing frequency of the switching tube is further increased, on one hand, the switching frequency of the switching tube is increased, so that the on-off time of the switching tube is shortened, and the on-off loss of the switching tube is reduced, thereby improving the efficiency of a circuit; on the other hand, the switching frequency of the switching tube is increased, the switching loss of the switching tube is also increased, and the harmonic wave in the output waveform is increased, so that the output waveform may be distorted, and the quality of electric energy output is reduced. Therefore, compared with the driving signal generated by the single modulation wave adopted in fig. 7, the driving signal adopted in fig. 8 controls the switching tube, the driving signal can further improve the efficiency of the circuit, and the power quality of the circuit output is reduced. Therefore, while increasing the switching frequency may increase the efficiency of an ANPC-type three-level circuit, it may also adversely affect the quality of the power output. In practical applications, a trade-off between efficiency and output quality is required, choosing an appropriate single-tone wave generation switching frequency.

the upper modulated wave of the dual modulated wave And the lower modulation wave/>The method comprises the following steps of:

，/>。

Wherein, Is the initial modulation wave, and when determining the upper modulation wave of the dual modulation wave, the initial modulation wave is minimized/>As said second zero sequence component. When determining the lower modulation wave of the dual modulation wave, maximum value/>, of the initial modulation waveAs said second zero sequence component.

The beneficial effects of one or more embodiments of the application are that: the single modulation wave carrier modulation and the double modulation wave carrier modulation can be used simultaneously in one transducer while maintaining the drive signal complementary logic. According to the amplitude change of the midpoint voltage fluctuation, two modulation modes are respectively selected, so that Shan Diaozhi wave carrier modulation and double modulation wave carrier modulation can be rapidly switched under the control logic without changing hardware connection and dead zone compensation and narrow pulse limitation, and midpoint voltage control and lower switching loss in the full power factor range are realized.

One or more embodiments of the application also disclose a controller. Referring to fig. 9, the controller includes a memory 100, a processor 200, and a computer program stored in the memory 100 and executable on the processor 200, which when executed by the processor 200, implements the ANPC type three-level converter control method as described above.

When the controller executes the control method of the ANPC type three-level converter, the midpoint voltage on the direct current bus can be monitored in real time by acquiring the midpoint voltage compacting value on the direct current bus; analyzing the fluctuation value of the neutral voltage compacting value relative to a preset neutral voltage value, wherein the preset neutral voltage value is a theoretical value calculated in an ideal state that the converter has no voltage fluctuation, and judging the fluctuation condition of the neutral voltage compacting value by taking the preset neutral voltage value as a reference; when the fluctuation value is smaller than the preset fluctuation value, the fact that the fluctuation of the midpoint voltage is smaller at the moment is indicated, a single modulation wave modulation strategy can be adopted to inhibit the fluctuation of the midpoint voltage, and single modulation waves of each phase are determined according to the first zero sequence component and the initial modulation waves of each phase, wherein the single modulation waves comprise upper modulation waves and lower modulation waves; when the fluctuation value is larger than or equal to a preset fluctuation value, the fact that the fluctuation of the midpoint voltage is larger at the moment is indicated, a single modulation wave modulation strategy cannot play a good role in inhibiting the fluctuation of the midpoint voltage, at the moment, the modulation strategy is switched, a double modulation wave modulation strategy is adopted, and double modulation waves of each phase are determined according to the first zero sequence component, the second zero sequence component and initial modulation waves of each phase, wherein the double modulation waves comprise upper modulation waves and lower modulation waves; the low-frequency fluctuation of the midpoint voltage is restrained in the full power factor range. Obtaining driving signals of each phase and driving complementary signals of each phase according to the upper modulation wave of each phase, the lower modulation wave of each phase, the upper carrier wave and the lower carrier wave; according to the driving signals of each phase and the driving complementary signals of each phase, the switching tubes of each phase on the ANPC three-level circuit are controlled, two switching tubes on the same bridge arm are guaranteed not to be simultaneously turned on, the state that the two switching tubes are alternately turned on is achieved, the continuous conduction time of a single switching tube is reduced, and the loss of the switching tubes is reduced. When the fluctuation value of the midpoint voltage is reduced from high to less than a preset fluctuation value, the control strategy is switched to a single modulation strategy again, at the moment, the switching frequency of the switching tube is reduced, the loss of the switching tube is reduced, the switching tube can dissipate heat in time, and the probability of damage and faults of the switching tube is reduced. The method does not need to change the hardware structure in the converter, and simultaneously considers two modulation strategies under the condition of keeping the complementary logic of the driving signal, thereby realizing midpoint voltage control and lower switching loss in the full power factor range.

The foregoing has outlined the basic principles, features, and advantages of the present application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present application, and various changes and modifications may be made therein without departing from the spirit and scope of the application, which is defined by the appended claims. The scope of the application is defined by the appended claims and equivalents thereof.

Claims

1. An ANPC type three-level converter control method, comprising:

Determining the fluctuation trend of a neutral point voltage compacting value according to the acquired neutral point voltage compacting value and a preset neutral point voltage value on a direct current bus, wherein the neutral point voltage compacting value is the voltage value of the direct current bus in an ANPC three-level circuit in the ANPC three-level converter;

determining modulation waves of each phase according to the fluctuation trend of the neutral-point voltage compacting value;

determining driving signals of each phase and driving complementary signals of each phase according to the modulated wave, the upper carrier wave and the lower carrier wave of each phase;

2. The ANPC type three-level converter control method of claim 1, wherein the determining the modulation wave of each phase according to the fluctuation trend of the neutral point electric compaction value includes:

Determining a corresponding zero sequence component and a modulation strategy according to the fluctuation trend;

3. The ANPC type three-level converter control method of claim 2, wherein the determining of the corresponding zero sequence component and modulation strategy is based on the ripple trend; determining the modulation wave of each phase according to the determined modulation strategy, the corresponding zero sequence component and the initial modulation wave of each phase comprises:

Under the condition that the fluctuation value of the neutral voltage value relative to the preset neutral voltage value is smaller than the preset fluctuation value, determining single modulation waves of each phase according to the first zero sequence component and the initial modulation waves of each phase, wherein the single modulation waves comprise an upper modulation wave and a lower modulation wave;

4. The ANPC type three-level converter control method of claim 3, wherein the determining the driving signal of each phase and the driving complementary signal of each phase based on the modulated wave, the upper carrier wave, and the lower carrier wave of each phase includes:

Comparing the upper modulation wave and the upper carrier wave of each phase to obtain an upper driving signal and an upper driving complementary signal of the corresponding phase;

Comparing the lower modulation wave and the lower carrier wave of each phase to obtain a lower driving signal and a lower driving complementary signal of the corresponding phase;

Comparing the lower modulation wave of each phase with the lower carrier wave under the condition that the initial modulation wave is larger than zero to obtain a middle driving signal and a middle driving complementary signal of the corresponding phase;

5. The ANPC type three-level converter control method of claim 4, wherein at least a partial phase of the ANPC three-level circuit includes an upper bridge arm, a middle bridge arm and a lower bridge arm, the upper bridge arm includes a first switching tube and a fifth switching tube, the middle bridge arm includes a second switching tube and a third switching tube, and the lower bridge arm includes a fourth switching tube and a sixth switching tube;

According to the upper driving signal, controlling the first switching tube in the upper bridge arm;

controlling the fifth switching tube in the upper bridge arm according to the upper driving complementary signal;

Controlling the second switching tube in the middle bridge arm according to the middle driving signal;

controlling the third switching tube in the middle bridge arm according to the middle driving complementary signal;

controlling the fourth switching tube in the lower bridge arm according to the lower driving signal;

6. The ANPC type three-level converter control method of claim 3, wherein before determining the corresponding zero sequence component and modulation strategy according to the ripple trend, further comprising:

determining a zero sequence component according to the initial modulation wave;

7. The ANPC type three-level converter control method of claim 6, wherein the determining a zero sequence component from the initial modulated wave includes:

Obtaining an initial modulation wave maximum value and an initial modulation wave minimum value according to the initial modulation wave;

The first zero sequence component is ；

The second zero sequence component is；

8. The ANPC type three-level converter control method of claim 7, wherein the determining a single modulation wave for each phase from the first zero sequence component and the initial modulation wave for each phase in the case where the fluctuation value of the midpoint voltage value with respect to the preset midpoint voltage value is smaller than a preset fluctuation value comprises:

The upper modulation wave of the single modulation wave is ，/>；

The lower modulation wave of the single modulation wave is，/>；

9. The ANPC type three-level converter control method of claim 7, wherein the determining the double modulation wave of each phase from the first zero sequence component, the second zero sequence component, and the initial modulation wave of each phase in the case where the ripple value is greater than or equal to the preset ripple value includes:

the upper modulation wave of the double modulation wave is ，/>；

The lower modulation wave of the double modulation wave is，/>；

10. The ANPC type three-level converter control method of claim 6, wherein the determining a zero sequence component from the initial modulated wave includes:

obtaining the distance from the initial modulation wave to the preset boundary according to the initial modulation wave and the preset boundary, wherein the distance from the initial modulation wave to the preset boundary comprises an upper boundary distance and a lower boundary distance;

determining the first zero sequence component according to the upper boundary distance and the lower boundary distance;

11. The ANPC type three-level converter control method of claim 10, wherein the obtaining a distance from the initial modulation wave to a preset boundary based on the initial modulation wave and the preset boundary includes:

The upper boundary distance is ，/>；

The lower boundary distance is，/>；

12. The ANPC type three-level converter control method of claim 10, wherein the obtaining a distance from the initial modulation wave to a preset boundary based on the initial modulation wave and the preset boundary includes:

The upper boundary distance And the lower boundary distance/>Respectively/>，/>；

13. The ANPC type three-level converter control method of claim 11 or 12, wherein the determining the first zero sequence component from the upper boundary distance and the lower boundary distance includes:

14. The ANPC type three-level converter control method of claim 13, wherein the determining a single modulation wave for each phase from the first zero sequence component and the initial modulation wave for each phase if the fluctuation value of the midpoint voltage value relative to the preset midpoint voltage value is less than a preset fluctuation value comprises:

The upper modulation wave of the single modulation wave is ，/>；

The lower modulation wave of the single modulation wave is，/>；

15. A controller comprising a memory, a processor and a computer program stored in the memory and executable on the processor, which when executed by the processor, implements the ANPC-type three-level converter control method of any one of claims 1-14.