CN114257102B - Double-sampling single-refreshing method based on three-phase two-level topological structure - Google Patents
Double-sampling single-refreshing method based on three-phase two-level topological structure Download PDFInfo
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- CN114257102B CN114257102B CN202011018478.9A CN202011018478A CN114257102B CN 114257102 B CN114257102 B CN 114257102B CN 202011018478 A CN202011018478 A CN 202011018478A CN 114257102 B CN114257102 B CN 114257102B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/084—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters using a control circuit common to several phases of a multi-phase system
- H02M1/0845—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters using a control circuit common to several phases of a multi-phase system digitally controlled (or with digital control)
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a double-sampling single-refreshing method based on a three-phase two-level topological structure, which comprises a three-phase full-control rectifier bridge, a direct-current bus capacitor, a three-phase full-control inverter bridge, a rectifier side, an LCL filter circuit on the inverter side and a series transformer coupled with grid voltage, wherein a controller DSP generates a modulation wave through operation, PWM signals are generated after PWM modulation to control the switching state of the three-phase full-control inverter bridge, specifically, the controller DSP generates the modulation wave through operation, a comparison threshold value of the amplitude of the modulation wave is set in the controller DSP, the modulation wave is sampled at the wave crest and the wave trough of a carrier, and the amplitude of the modulation wave obtained through actual sampling is compared with the comparison threshold value to determine the refreshing loading moment. The method effectively eliminates the problem of digital control delay and solves the adverse effect of control delay on the system.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a double-sampling single-refreshing method based on a three-phase two-level topological structure.
Background
With the application and development of power electronic devices, digital control based on the power electronic devices is widely used in the development due to superior performance. The method is highly applied to equipment for grid-connected inverters, energy storage converters and electric energy management. However, the inherent sampling calculation delay and PWM delay problems of digital control severely limit the control bandwidth of the system, and also affect the steady state and dynamic performance of the system.
The conventionally adopted method for reducing the control delay mainly comprises a peak-trough double-sampling refreshing method, a method for enabling sampling time to be close to refreshing time, a method for enabling multiple sampling refreshing and the like. The peak-trough double sampling refreshing is to sample the peak trough of the carrier wave, the modulation wave obtained by the current sampling calculation is updated at the next sampling moment, the method is still a mode of lag sampling essentially, and the lag is delayed for half a carrier wave period; the method of sampling for multiple times and the sampling time approaching to the refreshing time can effectively reduce the control delay, but the sampling time of the inductive current is not at the average value of the ripple wave of the inductive current, and the switching noise is introduced to influence the control of the system; still other scholars have studied predictive control, but this control depends on the accuracy of the control model of the system, and variations in the actual system hardware parameters tend to produce predictive deviations that affect the stability of the system. Although the above-mentioned approach reduces the control delay to some extent, the control delay is not completely eliminated, which still has some effect on the stability margin of the system.
The prior art commonly used double sampling double refresh modulation process for solving the problem of maximum duty cycle limited by sampling computation delay is shown in FIG. 1, in which V tri Is the triangular wave peak value of the carrier wave, V inv For inverting output voltage of topological bridge arm, V m For modulating the wave, it is defined herein that the modulated wave is greater than the carrier V tri When the PWM output is positive logic, the inverter outputs high level, namely the duty ratio is in direct proportion to the modulation wave; defining that the obtained modulated wave is V after the wave crest and the wave trough are sampled under the condition of no control delay m1 The method comprises the steps of carrying out a first treatment on the surface of the However, in practice, there is a sampling and computation delay T after the peak and trough sampling due to the sampling and computation delay of the DSP processor d The modulation wave obtained after time delay is V m2 。
Sampling calculation delay T d The maximum duty ratio of the output is limited, the modulation state is shown in the figure when the amplitude of the modulation wave is positive, and the delay time T is calculated due to sampling as shown in the interval (3) d A time greater than 50% of the negative duty cycle results in the modulated wave having intersected the carrier wave before the modulated wave was updated, thus limiting the magnitude of the output maximum duty cycle; when the amplitude of the modulated wave is negative, the modulated wave is intersected with the carrier wave before the modulated wave is updated when the amplitude of the modulated wave is larger than a certain degree and the modulated wave is calculated and updated through wave trough sampling; based on this, we can know the acquisitionThe delay time of sample calculation limits the size of the duty cycle from achieving a range of 0% -100%. Because the sampling delay limits the range of the duty cycle, the dual-sampling dual-refresh modulation mode in fig. 2 adopts a mode of lagging one-beat delay refresh to refresh the modulation wave, i.e. the modulation wave calculated in the current sampling period is not refreshed immediately but refreshed immediately at the beginning of the next sampling period, although the problem of the duty cycle limitation is solved, the bandwidth and the stability margin of the system are still affected by one-beat control delay.
How to solve the problems of the series active voltage quality regulator existing above is a matter that the person skilled in the art is dedicated to.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a double-sampling single-refreshing method based on a three-phase two-level topological structure.
In order to achieve the above purpose, the invention adopts the following technical scheme: the method comprises the steps that a three-phase two-level topological structure comprises a three-phase full-control rectifier bridge, a direct-current bus capacitor, a three-phase full-control inverter bridge, a rectifier side, an LCL filter circuit on the inverter side and a series transformer coupled with grid voltage, a controller DSP generates a modulation wave through operation, PWM signals are generated after PWM modulation to control the switching state of the three-phase full-control inverter bridge, specifically, the controller DSP generates the modulation wave through operation, a comparison threshold value of the amplitude of the modulation wave is set in the controller DSP, the modulation wave is sampled and calculated at the wave crest and the wave trough of a carrier wave, the amplitude of the modulation wave obtained through actual sampling is compared with the threshold value to determine the refreshing loading moment, and when the modulation wave is set to be larger than the threshold value, the modulation wave is refreshed immediately at the wave trough of the triangular carrier wave; when the modulation wave is set to be smaller than the threshold value, the modulation wave is refreshed immediately at the peak of the triangular carrier wave.
As a specific embodiment, the comparison threshold is set to 0, and if the amplitude of the modulation wave is 0, the output duty ratio is 50%; when the amplitude of the modulation wave is positive, the output duty ratio is more than 50%; when the amplitude of the modulated wave is negative, the duty cycle is less than 50%.
As a specific embodiment, the frequency of the sampling interrupt configured in the controller DSP is twice the carrier frequency.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
1) Compared with multiple sampling, the double-sampling single-refreshing method based on the three-phase two-level topological structure provided by the invention has the advantages that the sampling time is the switching-on and switching-off time of the switching tube, and the distortion of sampling signals caused by high-frequency switching noise is avoided;
2) In the invention, trough sampling is implemented and refreshed immediately when the modulation wave amplitude is positive, and the sampling at the wave crest is refreshed immediately when the modulation wave amplitude is negative, so that the digital control delay can be completely eliminated, the adverse effect of the control delay on the system is avoided, the system bandwidth is improved, and the stability margin of the system is increased;
3) In the invention, the frequency of the configuration sampling interruption in the controller is twice of the carrier frequency, so that the wave crest and wave trough sampling of the triangular carrier is realized, the time of refreshing and loading the modulated wave is judged according to the comparison between the amplitude of the modulated wave and the set threshold value, and the method is easy to realize in the controller DSP.
Drawings
FIG. 1 is a conventional double sampling double refreshing modulation process in the prior art;
FIG. 2 is a system architecture diagram of a three-phase two-level topology in accordance with the present invention;
fig. 3 is a diagram of a process of adjusting double sampling single refresh based on a three-phase two-level topology in the present invention.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and specific embodiments.
Referring to fig. 2, the three-phase two-level topological structure comprises a three-phase full-control rectifier bridge, a direct-current bus capacitor, a three-phase full-control inverter bridge, an LCL filter circuit at a rectifying side and an inverting side and a series transformer coupled with power grid voltage, wherein a controller DSP generates a modulation wave by performing operation processing on voltage and current signals acquired by an actual system, and generates PWM signals to control the switching state of the three-phase full-control inverter bridge after PWM modulation (namely, the modulation wave is compared with a carrier wave through a control loop output).
The controller DSP samples voltage and current double closed-loop control, the time for sampling and calculating a modulation wave is generally less than 1/4 of a switching period according to the running speed of the existing processor and the switching frequency of the system, the modulation wave is sampled at the wave crest and the wave trough of a carrier wave, the comparison threshold value of the amplitude of the modulation wave is set to be 0 in the controller DSP in a bipolar body modulation mode, and whether the amplitude of the modulation wave is greater than the threshold value is judged to determine the refreshing loading moment;
in the bipolar modulation mode, the output is set to be positive level when the modulation wave is larger than the carrier wave, the output duty ratio is fixed to be 50% when the modulation wave amplitude is 0, the output duty ratio is larger than 50% when the modulation wave amplitude is positive, and the output duty ratio is smaller than 50% when the modulation wave amplitude is negative, namely the negative duty ratio is larger than 50%;
the double-sampling single-refreshing method is specifically implemented as follows: when the amplitude of the modulated wave is positive, sampling calculation is carried out in the trough of the triangular carrier wave, and the modulated wave is refreshed immediately, so that the sampling calculation can be completed before the modulated wave intersects with the carrier wave, and the control delay can be eliminated well by carrying out the refresh immediately; when the negative value of the modulation wave is negative, sampling calculation is carried out at the peak of the triangular carrier wave, and the modulation wave is refreshed immediately, because the negative duty ratio is more than 50 percent and sampling is carried out at the peak, the fact that the sampling calculation of the modulation wave is completed before the modulation wave intersects with the triangular wave can be guaranteed after the sampling is completed, the change of 0-100 percent of the output duty ratio can be realized based on the fact, and the time delay of digital control is eliminated.
Referring to fig. 3, a process of double sampling single refresh based on a three-phase two-level topology is shown. Eight states exist in the modulation process according to the modulation process and the size of the three-phase modulation wave, and four cases of three phases in the positive half period of phase A in FIG. 3 are taken as an example for analysis; in interval (1), the A phase and C phase modulation wave at the wave crest and wave trough are positive values, the B phase modulation wave is negative values, the modulation wave calculated by the B phase is refreshed immediately at the wave crest, and the sampling delay T is prolonged d Less than half of the negative direction is occupiedTime (1-D) Ts/2 of the space ratio, the modulation wave calculated by the A phase and the C phase is refreshed immediately at the trough, and the sampling delay T is carried out d The forward duty ratio is less than half of the forward duty ratio D of each phase, and refreshing of the modulated wave can be completed before the interval modulated wave intersects with the carrier wave; in the interval (2), the A phase modulation wave and the C phase modulation wave at the wave crest are positive values, the B phase modulation wave is negative values, the B phase calculated modulation wave is refreshed immediately, the A phase modulation wave at the wave trough is positive values, the B phase modulation wave and the C phase modulation wave are negative values, and the A phase calculated modulation wave is refreshed immediately; in the interval (3), the A phase modulation wave at the wave crest and the wave trough is positive, the B phase modulation wave and the C phase modulation wave are negative, the modulation waves calculated by the B phase and the C phase are refreshed immediately at the wave crest, and the modulation waves calculated by the A phase are refreshed immediately at the wave trough; in the interval (4), the A phase modulation wave and the B phase modulation wave are positive values, the C phase modulation wave is negative values, the C phase calculated modulation wave is refreshed immediately at the wave crest, and the A phase modulation wave and the B phase modulation wave are refreshed immediately at the wave trough; the modulation process based on the double sampling single immediate refreshing can effectively eliminate the delay of digital control, improve the system bandwidth and increase the system stability.
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.
Claims (2)
1. The double-sampling single-refreshing method based on the three-phase two-level topological structure is characterized in that the three-phase two-level topological structure comprises a rectifying side LCL filter circuit, a three-phase full-control rectifier bridge, a direct-current bus capacitor, a three-phase full-control inverter bridge, an inversion side LCL filter circuit and a series transformer coupled with power grid voltage which are sequentially connected in series, a controller DSP generates a modulation wave through operation, PWM signals are generated after PWM modulation to control the switching state of the three-phase full-control inverter bridge, specifically, the controller DSP generates the modulation wave through operation, a threshold value of the amplitude of the modulation wave is set in the controller DSP, the modulation wave is sampled at the wave crest and the wave trough of a carrier, the amplitude of the modulation wave obtained through actual sampling is compared with the threshold value to determine refreshing loading time, sampling calculation is implemented at the wave trough of a triangular carrier wave when the set modulation wave is larger than the threshold value, and the modulation wave is refreshed immediately; when the modulation wave is set to be smaller than the threshold value, sampling calculation is carried out on the triangular carrier wave crest, the modulation wave is refreshed immediately, the threshold value is set to be 0, and when the amplitude value of the modulation wave is set to be 0, the output duty ratio is set to be 50%; when the amplitude of the modulation wave is positive, the output duty ratio is more than 50%; when the amplitude of the modulated wave is negative, the output duty cycle is less than 50%.
2. The method of double sampling single refresh based on a three-phase two-level topology according to claim 1, wherein the frequency of sampling interrupts configured in the controller DSP is twice the carrier frequency.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103178851A (en) * | 2013-03-15 | 2013-06-26 | 苏州科技学院 | Novel sampling method for generating SPWM (sinusoidal pulse width modulation) control signals |
| CN104298107A (en) * | 2014-08-26 | 2015-01-21 | 苏州科技学院 | Combined local frequency multiplication sampling algorithm for generating SPWM waves |
| CN106787875A (en) * | 2015-11-20 | 2017-05-31 | 台达电子企业管理（上海）有限公司 | Pulsed drive system and pulse drive method |
| CN107505497A (en) * | 2017-07-24 | 2017-12-22 | 同济大学 | A kind of passive magnetoelectricity signals of rotational speed sensor peak-to-peak value ime-domain measuring method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108599584B (en) * | 2017-03-08 | 2020-09-11 | 台达电子企业管理（上海）有限公司 | Modulation method of three-phase multi-level frequency converter |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103178851A (en) * | 2013-03-15 | 2013-06-26 | 苏州科技学院 | Novel sampling method for generating SPWM (sinusoidal pulse width modulation) control signals |
| CN104298107A (en) * | 2014-08-26 | 2015-01-21 | 苏州科技学院 | Combined local frequency multiplication sampling algorithm for generating SPWM waves |
| CN106787875A (en) * | 2015-11-20 | 2017-05-31 | 台达电子企业管理（上海）有限公司 | Pulsed drive system and pulse drive method |
| CN107505497A (en) * | 2017-07-24 | 2017-12-22 | 同济大学 | A kind of passive magnetoelectricity signals of rotational speed sensor peak-to-peak value ime-domain measuring method |
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