CN114257102A - 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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- CN114257102A CN114257102A CN202011018478.9A CN202011018478A CN114257102A CN 114257102 A CN114257102 A CN 114257102A CN 202011018478 A CN202011018478 A CN 202011018478A CN 114257102 A CN114257102 A CN 114257102A
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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
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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
- 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)
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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
- 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)
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Abstract
The invention discloses a double-sampling single-refreshing method based on a three-phase two-level topological structure, wherein the three-phase two-level topological structure comprises a three-phase fully-controlled rectifier bridge, a direct-current bus capacitor, a three-phase fully-controlled inverter bridge, an LCL (lower control limit) filter circuit on a rectification side and an inverter side and a series transformer coupled with a power grid voltage, a controller DSP (digital signal processor) generates a modulation wave through operation, a PWM (pulse-width modulation) signal is generated after PWM (pulse-width modulation) modulation to control the on-off state of the three-phase fully-controlled inverter bridge, specifically, the controller DSP generates the modulation wave through operation, a comparison threshold value of a modulation wave amplitude value is arranged in the controller DSP, the modulation wave is sampled at both the wave crest and the wave trough of a carrier, and the modulation wave amplitude value obtained through actual sampling is compared with the comparison threshold value to determine the refreshing loading time. 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 power electronic devices is widely applied and developed due to superior performance. The method is highly applied to grid-connected inverters, energy storage converters and electric energy management equipment. 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 method for refreshing by double sampling of wave crests and wave troughs, a method for refreshing by approaching the sampling time to the refreshing time, a method for refreshing by sampling for multiple times and the like. The peak-valley double sampling refreshing is to implement sampling at the peak and valley of the carrier wave, the modulation wave obtained by current sampling calculation is updated at the next sampling moment, and the method is still a lagging sampling mode essentially and lags for half a carrier wave period; the method of multiple sampling and the sampling time close 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 waves of the inductive current, and the influence of switching noise on the control of the system can be introduced; some researchers have studied predictive control, but the control depends on the accuracy of a control model of a system, and a change in an actual system hardware parameter is likely to cause a prediction deviation to affect the stability of the system. Although the above mentioned method reduces the control delay to some extent, the control delay is not completely eliminated, and still has a certain influence on the stability margin of the system.
The modulation process of dual-sampling dual refresh adopted to solve the problem of the sampling calculation delay limiting the maximum duty ratio in the prior art is shown in fig. 1, in which V istriIs the peak value of the carrier triangular wave, VinvFor inverting output voltage, V, of topological bridge armmFor modulating waves, defining the waves to be larger than the carrier wave VtriThe PWM output is positive logic, the inverter outputs high level, namely the duty ratio is formed by the modulation waveProportional ratio; defining the modulation wave obtained by refreshing immediately after sampling the wave crest and the wave trough as V under the condition of no control delaym1(ii) a However, in the actual situation, because the delay of sampling and calculation exists in the DSP processor, the sampling calculation delay T exists after the peak and the trough are sampleddThe modulated wave obtained after time delay is Vm2。
Sampling computation delay TdThe existence of (2) limits the maximum duty ratio of output, and the figure shows the modulation state when the modulation wave amplitude is a positive value, for example, the interval (c) shows that the delay time T is calculated due to samplingdThe time which is more than 50% of the negative duty ratio causes the modulation wave to be intersected with the carrier wave before the modulation wave is updated, so that the size of the maximum output duty ratio is limited; when the amplitude of the modulation wave is a negative value, the modulation wave is intersected with the carrier wave before the modulation wave is updated when the amplitude of the modulation wave is larger than a certain degree and the modulation wave is sampled, calculated and updated at the wave trough; based on the knowledge, the delay time of sampling calculation limits the size of the duty ratio to be incapable of realizing the change in the range of 0% -100%. Because the range of the duty ratio is limited by the sampling delay, the modulation mode of double-sampling double-refresh in fig. 2 refreshes the modulation wave in a delayed one-beat delay refresh mode, that is, the modulation wave calculated in the current sampling period is not refreshed immediately but refreshed immediately when the next sampling period starts, although the problem of the limitation of the duty ratio is solved, the bandwidth and the stability margin of the system are affected by the control delay of one beat.
How to solve the problems of the existing series active voltage quality regulator is the matter that the skilled person is dedicated to solve.
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 purpose, the invention adopts the technical scheme that: a double-sampling single-refreshing method based on a three-phase two-level topological structure comprises a three-phase fully-controlled rectifier bridge, a direct-current bus capacitor, a three-phase fully-controlled inverter bridge, an LCL filter circuit on a rectification side and an inversion side and a series transformer coupled with a power grid voltage, wherein a controller DSP generates a modulation wave through operation, a PWM signal is generated after PWM modulation to control the on-off state of the three-phase fully-controlled inverter bridge, specifically, the controller DSP generates the modulation wave through operation, a comparison threshold value of a modulation wave amplitude value is set in the controller DSP, the modulation wave carries out sampling calculation on the wave crest and the wave trough of a carrier, the modulation wave amplitude value obtained through actual sampling is compared with the threshold value to determine the time of refreshing loading, 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 a triangular carrier; and when the set modulation wave is 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 be 0, and if the modulation wave amplitude is 0, the output duty ratio is 50%; when the amplitude of the modulation wave is a positive value, the output duty ratio is more than 50 percent; when the amplitude of the modulation wave is negative, the duty ratio is less than 50%.
As a specific embodiment, the sampling interruption configured in the controller DSP has a frequency 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 sampling time is the on and off time of the switching tube, and the distortion of a sampling signal caused by high-frequency switching noise cannot be introduced;
2) in the invention, when the amplitude of the modulation wave is a positive value, the trough sampling is carried out and the refreshing is carried out immediately, and when the amplitude of the modulation wave is a negative value, the wave crest is sampled and refreshed immediately, so that the digital control delay can be completely eliminated, the adverse effect on the system caused by the control delay is avoided, the system bandwidth is improved, and the stability margin of the system is increased;
3) in the invention, the frequency of sampling interruption configured in the controller is twice of the carrier frequency, thereby realizing the peak-valley sampling of the triangular carrier wave, judging the moment of refreshing and loading the modulation wave according to the comparison between the amplitude of the modulation wave and the set threshold value, and being easy to realize in the DSP of the controller.
Drawings
FIG. 1 illustrates a conventional dual sampling and dual refresh modulation process in the prior art;
FIG. 2 is a system structure diagram of a three-phase two-level topology structure according to the present invention;
fig. 3 is a diagram of an adjustment process of double sampling single refresh based on a three-phase two-level topology structure in the present invention.
Detailed Description
The technical solution of the present invention is further explained with reference to the drawings and the specific embodiments.
Referring to fig. 2, the three-phase two-level topology includes a three-phase fully-controlled rectifier bridge, a dc bus capacitor, a three-phase fully-controlled inverter bridge, an LCL filter circuit at the rectifier side and the inverter side, and a series transformer coupled to a grid voltage, where a controller DSP generates a modulation wave by performing an operation on a voltage and current signal collected by an actual system, and generates a PWM signal to control a switching state of the three-phase fully-controlled inverter bridge after PWM modulation (i.e., the modulation wave is output through a control loop and compared with a carrier).
The controller DSP samples voltage and current for double closed-loop control, according to the running speed of the existing processor and the switching frequency of the system, the sampling and calculating time of a modulation wave is generally less than 1/4 switching cycles, the modulation wave samples at the wave crest and the wave trough of a carrier wave, under the mode of bipolar body modulation, a comparison threshold value of the amplitude value of the modulation wave is set to be 0 in the controller DSP, and whether the amplitude value of the modulation wave is greater than the threshold value is judged to determine the moment of refreshing and loading;
under the bipolar modulation mode, the output is positive level when the modulation wave is larger than the carrier wave, if the amplitude of the modulation wave is 0, the output duty ratio is fixed to 50%, when the amplitude of the modulation wave is positive, the output duty ratio is larger than 50%, and when the amplitude of the modulation wave is negative, the output duty ratio is smaller than 50%, namely the negative duty ratio is larger than 50%;
the double-sampling single-brushing method is implemented specifically as follows: when the amplitude of the modulation wave is a positive value, sampling calculation is carried out at the wave trough of the triangular carrier wave and the modulation wave is refreshed immediately, so that the sampling calculation can be completed before the modulation and the carrier wave are intersected, and the control delay can be well eliminated by refreshing immediately; when the negative value of the modulation wave is a negative value, sampling calculation is carried out at the peak of the triangular carrier wave and the modulation wave is refreshed immediately, and because the negative duty ratio is more than 50% and sampling is carried out at the peak, the modulation wave can be guaranteed to be sampled and calculated immediately after the sampling is finished and the modulation wave is still guaranteed to be finished before the modulation wave and the triangular wave are intersected, and the change of the output duty ratio of 0% -100% can be realized on the basis of the above, so that the 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. The modulation process has eight states according to the modulation process and the size of the three-phase modulation wave, and four cases of the three phases in the positive half period of the phase A in FIG. 3 are taken as an example for analysis; in the interval, the A-phase and C-phase modulated waves at the wave crest and the wave trough are positive values, the B-phase modulated wave is negative value, the modulated wave calculated by the B-phase is refreshed immediately at the wave crest, and the sampling delay T isdTime (1-D) Ts/2 less than half negative duty ratio, refreshing the modulated wave calculated by A phase and C phase at the trough, and sampling delay TdLess than half forward duty ratio D of each phase Ts/2, the refreshing of the modulation wave can be completed before the interval modulation wave intersects with the carrier wave; in the interval II, the A-phase and C-phase modulation waves at the wave crest are positive values, the B-phase modulation wave is a negative value, the modulation wave calculated for the B-phase is refreshed immediately, the A-phase modulation wave at the wave trough is a positive value, the B-phase and C-phase modulation waves are negative values, and the modulation wave calculated for the A-phase is refreshed immediately; in the third interval, the A phase modulation wave at the wave crest and the wave trough is a positive value, the B phase modulation wave and the C phase modulation wave are negative values, the B phase modulation wave and the C phase modulation wave calculated at the wave crest are refreshed immediately, and the A phase modulation wave calculated at the wave trough is refreshed immediately; in the interval (iv), the phase-A and phase-B modulated waves at the wave crest and the wave trough are positive values, the phase-C modulated wave is a negative value, the modulated wave calculated for the phase-C at the wave crest is refreshed immediately, and the modulated wave calculated for the phase-A and phase-B at the wave trough is refreshed immediately; 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 merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (3)
1. A double-sampling single-refreshing method based on a three-phase two-level topological structure is characterized in that the three-phase two-level topological structure comprises a three-phase fully-controlled rectifier bridge, a direct-current bus capacitor, a three-phase fully-controlled inverter bridge, an LCL filter circuit on a rectification side and an inverter side and a series transformer coupled with a power grid voltage, a controller DSP generates a modulation wave through operation, a PWM signal is generated through PWM modulation to control the on-off state of the three-phase fully-controlled inverter bridge, concretely, the controller DSP generates the modulation wave through operation, a threshold value of a modulation wave amplitude value is set in the controller DSP, the modulation wave is sampled at both a wave crest and a wave trough of a carrier wave, the moment of refreshing loading is determined through comparison between the modulation wave amplitude value obtained through actual sampling and the threshold value, when the modulation wave is set to be larger than the threshold value, sampling calculation is carried out at a wave trough of a triangular carrier wave, and the modulation wave is refreshed immediately; and when the set modulation wave is smaller than the threshold value, sampling calculation is carried out on the wave crest of the triangular carrier wave, and the modulation wave is refreshed immediately.
2. The method for double-sampling single refresh based on three-phase two-level topology structure as claimed in claim 1, wherein the threshold value is set to 0, if the modulation wave amplitude value is 0, the output duty ratio is 50%; when the amplitude of the modulation wave is a positive value, the output duty ratio is more than 50 percent; when the amplitude of the modulation wave is negative, the duty ratio is less than 50%.
3. The method of claim 1, wherein the sampling interrupt configured in the controller DSP has a frequency twice the carrier frequency.
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Citations (5)
| 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 |
| US20180262125A1 (en) * | 2017-03-08 | 2018-09-13 | Delta Electronics (Shanghai) Co.,Ltd. | Modulation method for a three-phase multilevel converter |
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- 2020-09-24 CN CN202011018478.9A patent/CN114257102B/en active Active
Patent Citations (5)
| 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 |
| US20180262125A1 (en) * | 2017-03-08 | 2018-09-13 | Delta Electronics (Shanghai) Co.,Ltd. | Modulation method for a three-phase multilevel converter |
| 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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