CN110943637B - Control method of non-isolated clamping type three-phase Heric photovoltaic inverter - Google Patents

Control method of non-isolated clamping type three-phase Heric photovoltaic inverter Download PDF

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CN110943637B
CN110943637B CN201910675252.7A CN201910675252A CN110943637B CN 110943637 B CN110943637 B CN 110943637B CN 201910675252 A CN201910675252 A CN 201910675252A CN 110943637 B CN110943637 B CN 110943637B
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phase
switch tube
bridge arm
tube
switching
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CN110943637A (en
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马海啸
张晓峰
兰摘星
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Nanjing University of Posts and Telecommunications
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Nanjing University of Posts and Telecommunications
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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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/487—Neutral point clamped inverters
    • 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
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
    • 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
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • 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
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/123—Suppression of common mode voltage or current
    • 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
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Inverter Devices (AREA)

Abstract

The invention relates to a control method of a non-isolated clamping type three-phase Heric photovoltaic inverter, which comprises the steps of respectively intercepting three sinusoidal modulation waves with 120-degree phase difference with one triangular carrier to obtain six switching tube preprocessing signals, and determining that the inverter works in a non-follow current mode and a follow current mode through judging the six switching tube preprocessing signals. According to the invention, firstly, the three-phase follow current circuit is used for saving energy feedback power supply when the inverter is in a follow current mode, so that the conversion efficiency of the inverter is improved; secondly, the selective conduction of the clamping switch tube not only reduces the amplitude of the common mode voltage, but also increases the frequency of the common mode voltage in the common mode loop to three times of the triangular carrier frequency, so that the impedance of the filter inductor in the common mode loop is increased, and the effect of inhibiting leakage current is achieved.

Description

Control method of non-isolated clamping type three-phase Heric photovoltaic inverter
Technical Field
The invention relates to a control method of a non-isolated clamping type three-phase Heric photovoltaic inverter, and belongs to the technical field of power electronic direct current-alternating current conversion.
Background
The photovoltaic inverter is required to have high conversion efficiency and low cost, can bear the adverse effect of large output voltage fluctuation of the photovoltaic cell, and the alternating current output of the inverter also needs to meet higher electric energy quality. The photovoltaic inverter can be classified into an isolated type and a non-isolated type according to whether an isolation transformer is provided or not. The isolated photovoltaic inverter realizes the electrical isolation between a power grid and a battery panel, ensures the safety of operators and equipment, and has the advantages of large volume, heavy weight, high cost and low system conversion efficiency. The non-isolated photovoltaic inverter structurally does not contain a transformer, so that the non-isolated photovoltaic inverter has the advantages of small size, light weight, low cost and the like, but the transformer is not used for electrical isolation, a parasitic capacitor between a photovoltaic cell panel and the ground forms a common-mode loop with the inverter, a filter inductor and a power grid, and leakage current can be generated in the loop along with the high-frequency switching action of a power switching device. The existence of leakage current can increase inverter output current harmonic content, increase electromagnetic interference to reduce the electric energy quality, cause the electric wire netting current distortion, cause certain power loss, simultaneously, the leakage current also brings certain hidden danger to operating personnel's safety, consequently, for guarantee personnel and equipment safety, the leakage current must be restrained in certain within range.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the control method of the non-isolation clamping type three-phase Heric photovoltaic inverter is provided, the common mode characteristic of the inverter can be effectively improved, the system conversion efficiency is improved, the common mode leakage current is restrained, and the safety of personnel and equipment is guaranteed.
The invention adopts the following technical scheme for solving the technical problems:
the control method of the non-isolated clamping type three-phase Heric photovoltaic inverter is provided, the inverter topology comprises a solar photovoltaic cell, a traditional three-phase bridge type inverter circuit, a three-phase output filter circuit and a three-phase load, and the control method is characterized by further comprising a three-phase follow current circuit and a clamping circuit; the traditional three-phase bridge inverter circuit comprises an A-phase upper bridge arm switch tube (S)a1) Phase A lower bridge arm switch tube (S)a2) B phase upper bridge arm switch tube (S)b1) B phase lower bridge arm switch tube (S)b2) C phase upper bridge arm switch tube (S)c1) And C phase lower bridge arm switch tube (S)c2) (ii) a The three-phase output filter circuit comprises an A-phase filter inductor (L)fa) B phase filter inductor (L)fb) C phase filter inductor (L)fc) Phase A filter capacitor (C)fa) Phase B filter capacitor (C)fb) And a C-phase filter capacitor (C)fc) (ii) a The three-phase load comprises an A-phase load (R)a) Phase B load (R)b) And C phase load (R)c) (ii) a The three-phase follow current circuit comprises an A-phase first follow current switch tube (S)a3) And a phase A second follow current switch tube (S)a4) B phase first follow current switch tube (S)b3) B phase second follow current switch tube (S)b4) C-phase first follow current switch tube (S)c3) And C phase second follow current switch tube (S)c4) (ii) a The clamping circuit comprises a first DC capacitor (C)dc1) A second DC capacitor (C)dc2) And a third DC capacitor (C)dc3) Upper clamping switch tube (S)H) And a lower clamp switch tube (S)L) (ii) a Wherein the solar photovoltaic cell (U)PV) Positive electrode of (2) and first direct current capacitor (C)dc1) The positive pole and the A phase upper bridge arm switch tube (S)a1) Collector electrode, B phase upper bridge arm switch tube (S)b1) Collector and C phase upper bridge arm switch tube (S)c1) Are respectively connected with the solar photovoltaic cell (U)PV) Negative electrode of (2) and a third direct current capacitor (C)dc3) Negative pole of (1), A phase lower arm switching tube (S)a2) Emitter, B-phase lower arm switch tube (S)b2) Emitter and C-phase lower bridge arm switching tube (S)c2) The emitting electrodes of the two phase bridge arm switching tubes are respectively connected with the point Q and the phase A (S)a1) Emitter of (2) and A phase lower bridge arm switching tube (S)a2) Collector electrode, A phase filter inductor (L)fa) And a first freewheeling switch tube of phase A (S)a3) The collector electrodes of the two phase bridge arm switching tubes are respectively connected with the points A and B (S)b1) Emitter of (2) and B phase lower bridge arm switch tube (S)b2) Collector electrode, B-phase filter inductor (L)fb) And a B-phase first freewheel switching tube (S)b3) The collector electrodes of the two bridge arm switching tubes are respectively connected with the points B and C (S)c1) Emitter and C-phase lower bridge arm switching tube (S)c2) Collector electrode, C phase filter inductor (L)fc) And a C-phase first freewheel switching tube (S)c3) Is connected to a point C and a first DC capacitor (C)dc1) And a second direct current capacitor (C)dc2) Positive pole, upper clamping switch tube (S)H) Are connected to a second direct current capacitor (C)dc2) Negative electrode of (2) and a third direct current capacitor (C)dc3) Positive and lower clamping switch tube (S)L) Are respectively connected with the upper clamping switch tube (S)H) Collector and lower clamping switch tube (S)L) Collector of (1), and A-phase second freewheel switching tube (S)a4) Collector of (2), and a B-phase second freewheel switching tube (S)b4) Collector and C-phase second freewheeling switch tube (S)c4) Are respectively connected with the collectors of the A-phase first follow current switching tubes (S)a3) Emitter of (2) and A phase second freewheeling switching tube (S)a4) Is connected with the emitting electrode of the B-phase first follow current switching tube (S)b3) Emitter of (2) and a B-phase second freewheeling switching tube (S)b4) Is connected with the emitting electrode of the C-phase first follow current switching tube (S)c3) Emitter of (2) and C-phase second freewheeling switching tube (S)c4) Is connected with the emitter of the A-phase filter inductor (L)fa) The other end of the first phase filter capacitor (C) is connected with the A phase filter capacitor (C)fa) Positive electrode and A phase load (R)a) Are connected with each other, a B-phase filter inductor (L)fb) The other end of the first capacitor and the B-phase filter capacitor (C)fb) Positive electrode and B phase load (R)b) Are connected with each other, a C-phase filter inductance (L)fc) And the other end of the filter capacitor (C) is connected with a phase C filter capacitor (C)fc) Positive electrode of (2) and C-phase load (R)c) Are connected to each other, and an A-phase filter capacitor (C)fa) Negative pole of (2) and B phase filter capacitor (C)fb) Negative pole, C phase filter capacitor (C)fc) Negative electrode of (2), A phase load (R)a) The other end of (2), B-phase load (R)b) The other end of (2) and a C-phase load (R)c) The other ends of the two are respectively connected with a point N;
the control method of the inverter includes the steps of:
the first step is as follows: sine-modulating the A phase by a wave (u)ra) B phase sine modulation wave (u)rb) And C phase sine modulation wave (u)rb) Respectively in the triangular carrier (u)c) Intersecting, obtaining six pre-processing signals u through a comparatora1'、ua2'、ub1'、ub2'、uc1' and uc2'；
The second step is that: dividing the working mode of the non-isolation clamping type three-phase Heric photovoltaic inverter into six non-follow current modes and two follow current modes by judging the preprocessed signals;
the third step: will preprocess the signal ua1'、ub1' and uc1' AND operation to obtain signal ugeL', to preprocess the signal ua2'、ub2' and uc2' AND operation to obtain signal ugeH', to preprocess the signal ua1'、ub1' and uc1Two by two are subjected to same or operation to obtain three signals, and the three signals are subjected to and operation to obtain a signal ut'；
The fourth step: will signal ugeL' sum signal ut' AND operation to obtain the lower clamping switch tube (S)L) Drive signal u ofgeLWill signal ugeH' sum signal ut' AND operation to obtain the upper clamping switch tube (S)H) Drive signal u ofgeHWill signal ugeL' sum signal ugeH' OR operation to obtain six-way switch tube of follow current circuit (S)a3、Sa4、Sb3、Sb4、Sc3And Sc4) Drive signal u ofge34；
The fifth step: will clamp the switch tube (S) downL) Drive signal u ofgeLAfter taking the logical negation, respectively comparing with the preprocessed signal ua1'、ub1' and uc1' obtaining A phase upper bridge arm switch tube (S) after AND operationa1) Drive signal ugea1B phase upper bridge arm switch tube (S)b1) Drive signal ugeb1And C phase upper bridge arm switch tube (S)c1) Drive signal ugec1. Will clamp the switch tube (S)H) Drive signal u ofgeHAfter taking the logical negation, respectively comparing with the preprocessed signal ua2'、ub2' and uc2' obtaining A phase lower bridge arm switch tube (S) after AND operationa2) Drive signal ugea2B phase lower bridge arm switch tube (S)b2) Drive signal ugeb2And C phase lower bridge arm switch tube (S)c2) Drive signal ugec2。
As a control method of the non-isolated clamp type three-phase Heric photovoltaic inverter according to the present invention, preferably, in the first step, the a-phase sinusoidal modulation wave (u) isra) B phase sine modulation wave (u)rb) And C phase sine modulation wave (u)rb) The phase difference is 120 degrees; a phase sine modulation wave (u)ra) And a triangular carrier (u)c) Intercept, when uraGreater than ucWhen the output is high, when uraLess than ucOutputting low level in time to obtain A phase upper bridge arm switch tube (S)a1) Is pre-processeda1', to preprocess the signal ua1' getting logical negation to get A phase lower bridge arm switch tube (S)a2) Is pre-processeda2', B phase sine modulation wave (u)rb) And a triangular carrier (u)c) Intercept, when urbGreater than ucWhen the output is high, when urbLess than ucOutputting low level in time to obtain B phase upper bridge arm switch tube (S)b1) Is pre-processedb1', to preprocess the signal ub1' taking logic negation to obtain B-phase lower bridge arm switch tube (S)b2) Is pre-processedb2', C phase sine modulation wave (u)rc) And a triangular carrier (u)c) Intercept, when urcGreater than ucWhen the output is high, when urcLess than ucOutputting low level in time to obtain C-phase upper bridge arm switch tube (S)c1) Is pre-processedc1', to preprocess the signal uc1' getting logical negation to get C phase lower bridge arm switch tube (S)c2) Is pre-processedc2'。
As the control method of the non-isolated clamping type three-phase Heric photovoltaic inverter, preferably, in the second step, when the inverter operates in the non-freewheeling mode, the a-phase upper arm switching tube (S)a1) Phase A lower bridge arm switch tube (S)a2) B phase upper bridge arm switch tube (S)b1) B phase lower bridge arm switch tube (S)b2) C phase upper bridge arm switch tube (S)c1) And C phase lower bridge arm switch tube (S)c2) Switching on and off according to SPWM control mode, and clamping switch tube (S)H) Lower clamping switch tube (S)L) And a follow current circuit six-way switch tube (S)a3、Sa4、Sb3、Sb4、Sc3And Sc4) Are all in an off state.
As the control method of the non-isolated clamping type three-phase Heric photovoltaic inverter, preferably, in the second step, when the inverter operates in the non-freewheeling mode, the a-phase upper arm switching tube (S)a1) Drive signal ugea1And A phase lower bridge arm switch tube (S)a2) Drive signal ugea2On the contrary, B phase upper arm switch tube (S)b1) Drive signal ugeb1And B phase lower bridge arm switch tube (S)b2) Drive signal ugeb2On the contrary, C-phase upper arm switch tube (S)c1) Drive signal ugec1And C phase lower bridge arm switch tube (S)c2) Drive signal ugec2The opposite is true.
As the control method of the non-isolated clamping type three-phase Heric photovoltaic inverter, preferably, in the second step, when the inverter operates in the freewheeling mode, the three-phase bridge arm six switching tubes (S)a1、Sa2、Sb1、Sb2、Sc1And Sc2) Six-way switch tube (S) of turn-off and follow current circuita3、Sa4、Sb3、Sb4、Sc3And Sc4) All are conducted, the clamping circuit clamps the switch tube up and down (S)HAnd SL) And selectively conducting. The specific scheme of selective conduction is as follows: if A phase upper bridge arm switch tube (S)a1) Is pre-processeda1', B phase upper bridge arm switch tube (S)b1) Is pre-processedb1' and C phase upper bridge arm switch tube (S)c1) Is pre-processedc1' simultaneously high level, the clamp switch tube is turned down (S)L) If the A-phase lower bridge arm switching tube is conducted (S)a2) Is pre-processeda2', B phase lower bridge arm switch tube (S)b2) Is pre-processedb2' and C phase lower bridge arm switch tube (S)c2) Is pre-processedc2' simultaneously high level, the upper clamp switch tube (S)H) And conducting.
As the control method of the non-isolated clamping type three-phase Heric photovoltaic inverter, preferably, when the inverter is controlled by the method, the common-mode voltage u of the inverter is controlledcmIs a square wave, the upper peak value of the square wave is 2UPV(ii)/3, lower peak is UPVAnd/3, the frequency is three times the triangular carrier frequency. The expression for the common mode voltage is:
ucm＝(uAQ+uBQ+uCQ)/3
wherein u isAQIs the potential difference between the A point and the Q point, uBQIs the potential difference between B point and Q point, uCQIs the potential difference between the point C and the point Q.
As the control method of the non-isolated clamping type three-phase Heric photovoltaic inverter, the switching state of the inverter is preferably defined as [ M [ ]1,M2,M3,M4,M5]。M1Representing the switching state of the switching tube of the A-phase bridge arm, M11 represents that the switching tube of the upper bridge arm of the A phase is conducted and the switching tube of the lower bridge arm is turned off, and M1When the switching tube of the upper bridge arm of the A phase is turned off and the switching tube of the lower bridge arm is turned on, M is 01Z represents that the switching tubes of the upper and lower bridge arms of the phase A are all turned off; m2Representing the switching state of the B-phase bridge arm switching tube, M21 represents that the switching tube of the upper bridge arm of the B phase is conducted and the switching tube of the lower bridge arm is turned off, and M2When the upper bridge arm switching tube of the B phase is turned off and the lower bridge arm switching tube of the B phase is turned on, M represents that M represents the number of the upper bridge arm switching tubes of the B phase2Z represents that the switching tubes of the upper and lower bridge arms of the B phase are all turned off; m3Representing the switching state of the C-phase bridge arm switching tube, M31 represents that the C-phase upper bridge arm switching tube is conducted and the lower bridge arm switching tube is turned off, and M3When the C-phase upper bridge arm switching tube is turned off and the lower bridge arm switching tube is turned on, M is 03Z represents that the switching tubes of the upper and lower bridge arms of the C phase are all turned off; m4Indicating the switching state of the upper and lower clamping switch tubes of the clamping circuit, M41 means that the upper clamping switch tube is conducted and the lower clamping switch tube is turned off, M4When the upper clamping switch tube is turned off and the lower clamping switch tube is turned on, M is equal to 04Z represents that the upper clamping switch tube and the lower clamping switch tube are both turned off; m5Indicating the switching state of the six switching tubes of the freewheel circuit, M51 indicates that six switching tubes of the follow current circuit are all conducted, M50 represents that the six switching tubes of the follow current circuit are all turned off;
therefore, the 6 non-freewheeling switching modes of the inverter are [1,0,0, Z,0], [1,1,0, Z,0], [0,1,1, Z,0], [0,0,1, Z,0] and [1,0,1, Z,0], respectively, and the 2 freewheeling switching modes are [ Z,1,1] and [ Z,0,1], respectively.
Compared with the prior art, the non-isolated clamping type three-phase Heric photovoltaic inverter topology three-phase follow current circuit has the following technical advantages that the inverter is enabled not to flow through a direct current power supply in the follow current stage due to the addition of the non-isolated clamping type three-phase Heric photovoltaic inverter topology three-phase follow current circuit, so that the energy feedback is omitted, and the conversion efficiency of the inverter is improved; the clamping circuit is added, so that the common-mode voltage of the inverter at the follow current stage is clamped to be 1/3 and 2/3 of the direct-current input voltage, the amplitude of the common-mode voltage is reduced, the frequency of the common-mode voltage in the common-mode loop is three times of the frequency of a triangular carrier wave through selective conduction of the upper clamping switch tube and the lower clamping switch tube, the impedance of a filter inductor in the loop is increased, the leakage current of the photovoltaic inverter is restrained, and the safety of personnel and equipment in use is ensured.
Drawings
The invention will be further described with reference to the accompanying drawings.
Fig. 1 is a main circuit structure diagram of a non-isolated clamping type three-phase Heric photovoltaic inverter topology.
Fig. 2 is a schematic diagram of the generation of control signals of a non-isolated clamped three-phase Heric photovoltaic inverter.
Fig. 3 is a timing diagram of driving signals of a non-isolation clamping type three-phase Heric photovoltaic inverter.
Fig. 4 is a schematic diagram of a first mode of a non-isolated clamped three-phase Heric photovoltaic inverter.
Fig. 5 is a schematic diagram of a second mode of a non-isolated clamped three-phase Heric photovoltaic inverter.
Fig. 6 is a schematic diagram of a mode three of a non-isolated clamped three-phase Heric photovoltaic inverter.
Fig. 7 is a schematic diagram of a non-isolation clamp type three-phase Heric photovoltaic inverter mode four.
Fig. 8 is a schematic diagram of a mode five of a non-isolated clamped three-phase Heric photovoltaic inverter.
Fig. 9 is a schematic diagram of a non-isolated clamped three-phase Heric photovoltaic inverter mode six.
Fig. 10 is a schematic diagram of a non-isolated clamped three-phase Heric photovoltaic inverter mode seven.
Fig. 11 is a schematic diagram of a mode eight of a non-isolated clamped three-phase Heric photovoltaic inverter.
Fig. 12 is a schematic diagram of a common-mode voltage of a non-isolated clamped three-phase Heric photovoltaic inverter.
Detailed Description
The technical scheme of the invention is further explained by combining the accompanying drawings as follows:
the technical solution of the invention is to provide a control method of a non-isolated clamping type three-phase Heric photovoltaic inverter, the inverter structure is shown as figure 1, and the control method comprises the following stepsThe solar photovoltaic cell comprises a solar photovoltaic cell, a traditional three-phase bridge type inverter circuit, a three-phase output filter circuit and a three-phase load, and is characterized by further comprising a three-phase follow current circuit and a clamping circuit; the traditional three-phase bridge inverter circuit comprises an A-phase upper bridge arm switch tube (S)a1) Phase A lower bridge arm switch tube (S)a2) B phase upper bridge arm switch tube (S)b1) B phase lower bridge arm switch tube (S)b2) C phase upper bridge arm switch tube (S)c1) And C phase lower bridge arm switch tube (S)c2) (ii) a The three-phase output filter circuit comprises an A-phase filter inductor (L)fa) B phase filter inductor (L)fb) C phase filter inductor (L)fc) Phase A filter capacitor (C)fa) Phase B filter capacitor (C)fb) And a C-phase filter capacitor (C)fc) (ii) a The three-phase load comprises an A-phase load (R)a) Phase B load (R)b) And C phase load (R)c) (ii) a The three-phase follow current circuit comprises an A-phase first follow current switch tube (S)a3) And a phase A second follow current switch tube (S)a4) B phase first follow current switch tube (S)b3) B phase second follow current switch tube (S)b4) C-phase first follow current switch tube (S)c3) And C phase second follow current switch tube (S)c4) (ii) a The clamping circuit comprises a first DC capacitor (C)dc1) A second DC capacitor (C)dc2) And a third DC capacitor (C)dc3) Upper clamping switch tube (S)H) And a lower clamp switch tube (S)L) (ii) a Wherein the solar photovoltaic cell (U)PV) Positive electrode of (2) and first direct current capacitor (C)dc1) The positive pole and the A phase upper bridge arm switch tube (S)a1) Collector electrode, B phase upper bridge arm switch tube (S)b1) Collector and C phase upper bridge arm switch tube (S)c1) Are respectively connected with the solar photovoltaic cell (U)PV) Negative electrode of (2) and a third direct current capacitor (C)dc3) Negative pole of (1), A phase lower arm switching tube (S)a2) Emitter, B-phase lower arm switch tube (S)b2) Emitter and C-phase lower bridge arm switching tube (S)c2) The emitting electrodes of the two phase bridge arm switching tubes are respectively connected with the point Q and the phase A (S)a1) Emitter of (2) and A phase lower bridge arm switching tube (S)a2) Collector electrode, A phase filter inductor (L)fa) And a first freewheeling switch tube of phase A (S)a3) Are respectively connected with the collector electrodesAt point A, B phase upper bridge arm switch tube (S)b1) Emitter of (2) and B phase lower bridge arm switch tube (S)b2) Collector electrode, B-phase filter inductor (L)fb) And a B-phase first freewheel switching tube (S)b3) The collector electrodes of the two bridge arm switching tubes are respectively connected with the points B and C (S)c1) Emitter and C-phase lower bridge arm switching tube (S)c2) Collector electrode, C phase filter inductor (L)fc) And a C-phase first freewheel switching tube (S)c3) Is connected to a point C and a first DC capacitor (C)dc1) And a second direct current capacitor (C)dc2) Positive pole, upper clamping switch tube (S)H) Are connected to a second direct current capacitor (C)dc2) Negative electrode of (2) and a third direct current capacitor (C)dc3) Positive and lower clamping switch tube (S)L) Are respectively connected with the upper clamping switch tube (S)H) Collector and lower clamping switch tube (S)L) Collector of (1), and A-phase second freewheel switching tube (S)a4) Collector of (2), and a B-phase second freewheel switching tube (S)b4) Collector and C-phase second freewheeling switch tube (S)c4) Are respectively connected with the collectors of the A-phase first follow current switching tubes (S)a3) Emitter of (2) and A phase second freewheeling switching tube (S)a4) Is connected with the emitting electrode of the B-phase first follow current switching tube (S)b3) Emitter of (2) and a B-phase second freewheeling switching tube (S)b4) Is connected with the emitting electrode of the C-phase first follow current switching tube (S)c3) Emitter of (2) and C-phase second freewheeling switching tube (S)c4) Is connected with the emitter of the A-phase filter inductor (L)fa) The other end of the first phase filter capacitor (C) is connected with the A phase filter capacitor (C)fa) Positive electrode and A phase load (R)a) Are connected with each other, a B-phase filter inductor (L)fb) The other end of the first capacitor and the B-phase filter capacitor (C)fb) Positive electrode and B phase load (R)b) Are connected with each other, a C-phase filter inductance (L)fc) And the other end of the filter capacitor (C) is connected with a phase C filter capacitor (C)fc) Positive electrode of (2) and C-phase load (R)c) Are connected to each other, and an A-phase filter capacitor (C)fa) Negative pole of (2) and B phase filter capacitor (C)fb) Negative pole, C phase filter capacitor (C)fc) Negative electrode of (2), A phase load (R)a) The other end of (2), B-phase load (R)b) The other end of (1) and a C-phase load(Rc) The other ends of the two are respectively connected with a point N;
the control method of the inverter is shown in fig. 2 and 3, and comprises the following steps:
the first step is as follows: sine-modulating the A phase by a wave (u)ra) B phase sine modulation wave (u)rb) And C phase sine modulation wave (u)rb) Respectively in the triangular carrier (u)c) Intersecting, obtaining six pre-processing signals u through a comparatora1'、ua2'、ub1'、ub2'、uc1' and uc2'；
The second step is that: dividing the working mode of the non-isolation clamping type three-phase Heric photovoltaic inverter into six non-follow current modes and two follow current modes by judging the preprocessed signals;
the third step: will preprocess the signal ua1'、ub1' and uc1' AND operation to obtain signal ugeL', to preprocess the signal ua2'、ub2' and uc2' AND operation to obtain signal ugeH', to preprocess the signal ua1'、ub1' and uc1Two by two are subjected to same or operation to obtain three signals, and the three signals are subjected to and operation to obtain a signal ut'；
The fourth step: will signal ugeL' sum signal ut' AND operation to obtain the lower clamping switch tube (S)L) Drive signal u ofgeLWill signal ugeH' sum signal ut' AND operation to obtain the upper clamping switch tube (S)H) Drive signal u ofgeHWill signal ugeL' sum signal ugeH' OR operation to obtain six-way switch tube of follow current circuit (S)a3、Sa4、Sb3、Sb4、Sc3And Sc4) Drive signal u ofge34；
The fifth step: will clamp the switch tube (S) downL) Drive signal u ofgeLAfter taking the logical negation, respectively comparing with the preprocessed signal ua1'、ub1' and uc1' obtaining A phase upper bridge arm switch tube (S) after AND operationa1) Drive signal ugea1B phase upper bridge arm switch tube (S)b1) Drive signal ugeb1And C phase upper bridge arm switch tube (S)c1) Drive signal ugec1. Will clamp the switch tube (S)H) Drive signal u ofgeHAfter taking the logical negation, respectively comparing with the preprocessed signal ua2'、ub2' and uc2' obtaining A phase lower bridge arm switch tube (S) after AND operationa2) Drive signal ugea2B phase lower bridge arm switch tube (S)b2) Drive signal ugeb2And C phase lower bridge arm switch tube (S)c2) Drive signal ugec2。
Fig. 3 shows a timing diagram of driving signals of the switching tube in the control method of the present invention, where waveforms from top to bottom are: a-phase upper bridge arm switch tube Sa1Voltage waveform u between gate and emittergea1(ii) a A-phase lower bridge arm switch tube Sa2Voltage waveform u between gate and emittergea2(ii) a B-phase upper bridge arm switch tube Sb1Voltage waveform u between gate and emittergeb1(ii) a B-phase lower bridge arm switch tube Sb2Voltage waveform u between gate and emittergeb2(ii) a C-phase upper bridge arm switch tube Sc1Voltage waveform u between gate and emittergec1(ii) a C-phase lower bridge arm switch tube Sc2Voltage waveform u between gate and emittergec2(ii) a Upper clamping switch tube SHVoltage waveform u between gate and emittergeH(ii) a Lower clamping switch tube SLVoltage waveform u between gate and emittergeL(ii) a Six switching tubes S of follow current circuita3、Sa4、 Sb3、Sb4、Sc3And Sc4Voltage waveform u between gate and emitterge34。
In addition, the inverter switch state is defined as [ M ]1,M2,M3,M4,M5]。M1Representing the switching state of the switching tube of the A-phase bridge arm, M11 represents that the switching tube of the upper bridge arm of the A phase is conducted and the switching tube of the lower bridge arm is turned off, and M1When the switching tube of the upper bridge arm of the A phase is turned off and the switching tube of the lower bridge arm is turned on, M is 01Z represents that the switching tubes of the upper and lower bridge arms of the phase A are all turned off; m2Representing the switching state of the B-phase bridge arm switching tube, M21 represents a B-phase upper bridge arm switching tubeConducting and switching tube of lower bridge arm is turned off, M2When the upper bridge arm switching tube of the B phase is turned off and the lower bridge arm switching tube of the B phase is turned on, M represents that M represents the number of the upper bridge arm switching tubes of the B phase2Z represents that the switching tubes of the upper and lower bridge arms of the B phase are all turned off; m3Representing the switching state of the C-phase bridge arm switching tube, M31 represents that the C-phase upper bridge arm switching tube is conducted and the lower bridge arm switching tube is turned off, and M3When the C-phase upper bridge arm switching tube is turned off and the lower bridge arm switching tube is turned on, M is 03Z represents that the switching tubes of the upper and lower bridge arms of the C phase are all turned off; m4Indicating the switching state of the upper and lower clamping switch tubes of the clamping circuit, M41 means that the upper clamping switch tube is conducted and the lower clamping switch tube is turned off, M4When the upper clamping switch tube is turned off and the lower clamping switch tube is turned on, M is equal to 04Z represents that the upper clamping switch tube and the lower clamping switch tube are both turned off; m5Indicating the switching state of the six switching tubes of the freewheel circuit, M51 indicates that six switching tubes of the follow current circuit are all conducted, M5And 0 represents that the six switching tubes of the freewheeling circuit are all turned off.
Therefore, the 6 non-freewheeling switching modes of the inverter are [1,0,0, Z,0], [1,1,0, Z,0], [0,1,1, Z,0], [0,0,1, Z,0] and [1,0,1, Z,0], respectively, and the 2 freewheeling switching modes are [ Z,1,1] and [ Z,0,1], respectively. The modes are shown in fig. 4 to 11, and the working principle of the inverter in each mode is briefly analyzed as follows:
the first mode is as follows: as shown in FIG. 4, the inverter switching states are [1,0,0, Z,0]Switching tube Sa1、 Sb2And Sc2Is high level, Sa1、Sb2And Sc2In a conducting state; switch tube Sa2、Sb1、Sc1、Sa3、Sa4、Sb3、Sb4、Sc3、Sc4、SHAnd SLIs low level, Sa2、Sb1、Sc1、Sa3、Sa4、Sb3、 Sb4、Sc3、Sc4、SHAnd SLIn an off state. The current flows from the positive pole of the power supply and flows through Sa1—Lfa—Ra-midpoint N —Rb、Rc—Lfb、Lfc—Sb2、Sc2And then flows back to the negative electrode of the power supply after being grouped. At this time uAQ＝UPV，uBQ＝uCQ0, so the common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝UPV/3。
Mode two: as shown in FIG. 5, the inverter switching states are [1,1,0, Z,0]]Switching tube Sa1、 Sb1And Sc2Is high level, Sa1、Sb1And Sc2In a conducting state; switch tube Sa2、Sb2、Sc1、Sa3、Sa4、Sb3、Sb4、Sc3、Sc4、SHAnd SLIs low level, Sa2、Sb2、Sc1、Sa3、Sa4、Sb3、Sb4、 Sc3、Sc4、SHAnd SLIn an off state. The current flows from the positive pole of the power supply and flows through Sa1、 Sb1—Lfa、Lfb—Ra、RbMidpoint N-Rc—Lfc—Sc2And then flows back to the negative electrode of the power supply after being grouped. At this time uAQ＝uBQ＝UPV，uCQ0, so the common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝2UPV/3。
Mode three: as shown in FIG. 6, the inverter switching states are [0,1,0, Z,0]]Switching tube Sa2、 Sb1And Sc2Is high level, Sa2、Sb1And Sc2In a conducting state; switch tube Sa1、Sb2、Sc1、Sa3、Sa4、Sb3、Sb4、Sc3、Sc4、SHAnd SLIs low level, Sa1、Sb2、Sc1、Sa3、Sa4、Sb3、 Sb4、Sc3、Sc4、SHAnd SLIn an off state. The current flows from the positive pole of the power supply and flows through Sb1—Lfb—RbMidpoint N-Ra、Rc—Lfa、Lfc—Sa2、Sc2And then flows back to the negative electrode of the power supply after being grouped. At this time uAQ＝uCQ＝0，uBQ＝UPVSo that the common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝UPV/3。
And a fourth mode: as shown in FIG. 7, the inverter switching states are [0,1,1, Z,0]]Switching tube Sa2、 Sb1And Sc1Is high level, Sa2、Sb1And Sc1In a conducting state; switch tube Sa1、Sb2、Sc2、Sa3、Sa4、Sb3、Sb4、Sc3、Sc4、SHAnd SLIs low level, Sa1、Sb2、Sc2、Sa3、Sa4、Sb3、Sb4、 Sc3、Sc4、SHAnd SLIn an off state. The current flows from the positive pole of the power supply and flows through Sb1、 Sc1—Lfb、Lfc—Rb、RcMidpoint N-Ra—Lfa—Sa2And then flows back to the negative electrode of the power supply after being grouped. At this time uAQ＝0，uBQ＝uCQ＝UPVSo that the common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝2UPV/3。
A fifth mode: as shown in FIG. 8, the inverter switching states are [0,0,1, Z,0]]Switching tube Sa2、 Sb2And Sc1Is high level, Sa2、Sb2And Sc1In a conducting state; switch tube Sa1、Sb1、Sc2、Sa3、Sa4、Sb3、Sb4、Sc3、Sc4、SHAnd SLIs low level, Sa1、Sb1、Sc2、Sa3、Sa4、Sb3、 Sb4、Sc3、Sc4、SHAnd SLIn an off state. The current flows from the positive pole of the power supply and flows through Sc1—Lfc—RcMidpoint N-Ra、Rb—Lfa、Lfb—Sa2、Sb2And then flows back to the negative electrode of the power supply after being grouped. At this time uAQ＝uBQ＝0，uCQ＝UPVSo that the common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝UPV/3。
A sixth mode: as shown in FIG. 9, the inverter switching states are [1,0,1, Z,0]]Switching tube Sa1、 Sb2And Sc1Is high level, Sa1、Sb2And Sc1In a conducting state; switch tube Sa2、Sb1、Sc2、Sa3、Sa4、Sb3、Sb4、Sc3、Sc4、SHAnd SLIs low level, Sa2、Sb1、Sc2、Sa3、Sa4、Sb3、Sb4、 Sc3、Sc4、SHAnd SLIn an off state. The current flows from the positive pole of the power supply and flows through Sa1、 Sc1—Lfa、Lfc—Ra、RcMidpoint N-Rb—Lfb—Sb2And then flows back to the negative electrode of the power supply after being grouped. At this time uAQ＝uCQ＝UPV，uBQ0, so the common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝2UPV/3。
A seventh mode: as shown in FIG. 10, the inverter switching states are [ Z, Z, Z,1 [ ]]. Once switch tube Sa2、Sb2And Sc2Is simultaneously high level, Sa2、Sb2And Sc2In a conducting state, the switch tube Sa1、Sa2、Sb1、Sb2、Sc1、Sc2Requiring immediate turn-off of the freewheeling switch tube Sa3、Sa4、Sb3、Sb4、Sc3And Sc4And an upper clamping switch tube SHOn and the current enters the freewheeling stage. The former state of the mode is generally that two of three switching tubes of the lower bridge arm are conducted, and here, the mode one enters the mode seven, and other conditions are similar. At this time, the inductor current flows, and the current flows through L in sequencefa—RaMidpoint N-Rb、Rc—Lfb、Lfc—Sb3、Sc3—Sb4(body diode), Sc4(body diode) -Sa4— Sa3(body diode). In the follow current stage, the solar cell panel is disconnected from the power grid, and the upper clamping switch tube SHConduction clamps the potential at the point of A, B and C to 2/3 of the input voltage, when u isAQ＝uBQ＝uCQ＝2UPV/3, so common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝2UPV/3。
The mode is eight: as shown in FIG. 11, the inverter switching states are [ Z, Z, Z,0,1]]. Once switch tube Sa1、Sb1And Sc1Is simultaneously high level, Sa1、Sb1And Sc1In a conducting state, the switch tube Sa1、Sa2、Sb1、Sb2、Sc1、Sc2Requiring immediate turn-off of the freewheeling switch tube Sa3、Sa4、Sb3、Sb4、Sc3And Sc4And a lower clamping switch tube SLOn and the current enters the freewheeling stage. The former state of the mode is generally that two of three switching tubes of the upper bridge arm are conducted, and the mode two enters the mode eight as an example, and other conditions are similar. At this time, the inductor current flows, and the current flows through L in sequencefa、Lfb—Ra、RbMidpoint N-Rc—Lfc—Sc3—Sb4(body diode) -Sa4、Sb4—Sa3(body diode), Sb3(body diode). In the follow current stage, the solar cell panel is disconnected from the power grid, and the lower clamping switch tube SLConduction clamps the potential at the point of A, B and C to 1/3 of the input voltage, when u isAQ＝uBQ＝uCQ＝UPV/3, so common mode voltage ucm＝(uAQ+uBQ+uCQ)/3＝UPV/3。
With reference to the timing diagram of the driving signal of the switching tube and the eight different switching modes in the inverter control method of the present invention shown in fig. 3, the specific mode switching process sequentially starts from zero time: seven [ Z, Z, Z,1,1] -mode five [0,0,1, Z,0] -mode six [1,0,1, Z,0] -mode eight [ Z, Z, Z,0,1] -mode six [1,0,1, Z,0] -mode one [1,0,0, Z,0] -mode seven [ Z, Z,1,1] -mode one [1,0,0, Z,0] -mode two [1,1,0, Z,0] -mode eight [ Z, Z, Z,0,1] -mode two [1,1,0, Z,0, 0] -mode three [0,1,0, Z,0, 0] -mode seven [ Z, Z,1,1] -three [0,1,0, Z,0] -four [0,1,1, 1, Z,0] -mode four [ Z,0,1, 1, Z,0] -mode Z,0,1, 1, Z,0, 0,1,1, 1, Z,0, 0] -mode four [0,1, Z,0, 0,1,1, Z,0, 0],0, 1,1, 1, Z,0, 0,0,1, 0, Z,0, 0,1,1, 1,0,0, 1, Z,0, 0,1,1, 0,0, 0,1,1, 1,0,0, 1,1, 1,0,0, 0,1,1, 1,0,0, 0,1,1, 1,0,1, 1,0,0, 0,1,1, 1,0,0, 1,1,0, 0,1,1, 0,0, 0,1,1, 0,0, 0,1,1, 0,0,1, 1,0,0, 0,1,1, 0,0, 0,1,1, 0,1,1, 0,1, Z,0] -mode hepta [ Z, Z, Z,1,1 ].
Fig. 12 is a schematic diagram of common mode voltage in the control method of the present invention, and it can be seen from the diagram that the common mode voltage is a square wave, and the upper peak value of the square wave is 2UPV(ii)/3, lower peak is UPVAnd/3, the frequency is three times the triangular carrier frequency.
From the above analysis, since the voltage of the freewheeling loop of the inverter is clamped to one third and two thirds of the input voltage, the amplitude of the common mode voltage of the inverter varies from 0 to U of the conventional three-phase bridge inverter during the entire inversion periodPVReduced to UPV/3～2UPVAnd/3, due to the selective conduction of the upper and lower clamping switch tubes, the frequency of the common-mode voltage in the whole inversion period is three times of the triangular carrier frequency, and the impedance of the filter inductor in the common-mode loop is increased. Due to the reduction of the amplitude and the increase of the frequency of the common-mode voltage, the leakage current in the common-mode loop can be effectively inhibited, the electromagnetic interference of the system is reduced, and the improvement of the common-mode voltageThe quality of electric energy reduces the distortion rate of the power grid and ensures the safety of personnel and equipment.
In conclusion, the invention solves the technical problems of large leakage current, low conversion efficiency and the like of the non-isolated three-phase photovoltaic inverter, provides a method for inhibiting the leakage current of the non-isolated three-phase photovoltaic inverter, and has a certain engineering application value.
The above description is only for the purpose of illustrating the embodiments of the present invention and should not be taken as limiting the scope of the present invention, and any equivalent changes and modifications made by those skilled in the art without departing from the spirit and principle of the present invention should fall within the protection scope of the present invention.

Claims (7)

1. A control method of a non-isolation clamping type three-phase Heric photovoltaic inverter is characterized by comprising the following steps:
the inverter topology comprises a solar photovoltaic cell, a traditional three-phase bridge inverter circuit, a three-phase output filter circuit, a three-phase load, a three-phase follow current circuit and a clamping circuit; the traditional three-phase bridge inverter circuit comprises an A-phase upper bridge arm switch tube Sa1Phase A lower bridge arm switch tube Sa2B phase upper bridge arm switch tube Sb1B-phase lower bridge arm switch tube Sb2C-phase upper bridge arm switch tube Sc1And C-phase lower bridge arm switching tube Sc2(ii) a The three-phase output filter circuit comprises an A-phase filter inductor LfaB-phase filter inductor LfbC-phase filter inductor LfcPhase A filter capacitor CfaB phase filter capacitor CfbAnd C phase filter capacitor Cfc(ii) a The three-phase load comprises an A-phase load RaB phase load RbAnd C phase load Rc(ii) a The three-phase follow current circuit comprises an A-phase first follow current switch tube Sa3A phase second follow current switch tube Sa4B-phase first follow current switch tube Sb3B-phase second follow current switch tube Sb4C-phase first follow current switch tube Sc3And C-phase second follow current switch tube Sc4(ii) a The clamping circuit comprises a first DC capacitor Cdc1A second DC capacitor Cdc2And a third DC capacitor Cdc3Upper clamping switch tube SHAnd a lower clamping switch tubeSL(ii) a Wherein the solar photovoltaic cell UPVPositive electrode and first direct current capacitor Cdc1The positive pole and the A phase upper bridge arm switch tube Sa1Collector and B-phase upper bridge arm switching tube Sb1Collector and C-phase upper bridge arm switch tube Sc1The collector electrodes of the solar photovoltaic cell U are respectively connectedPVNegative pole of and third direct current capacitor Cdc3Is connected to the lower arm switching tube S of the Q, A phasea2Emitter and B-phase lower bridge arm switch tube Sb2Emitter and C-phase lower bridge arm switch tube Sc2The emitting electrode of the phase A is connected with a point Q, and the phase A upper bridge arm switch tube Sa1Emitter and A-phase lower bridge arm switching tube Sa2Collector electrode, A phase filter inductor LfaAnd a first freewheeling switch tube S of phase Aa3The collectors of the two bridge arm switching tubes are respectively connected with the points A and Bb1Emitter and B-phase lower bridge arm switching tube Sb2Collector electrode, B-phase filter inductor LfbAnd a B-phase first follow current switching tube Sb3The collectors of the two bridge arm switching tubes are respectively connected with the points B and Cc1Emitter and C-phase lower bridge arm switching tube Sc2Collector electrode, C phase filter inductor LfcAnd a C-phase first follow current switching tube Sc3The collectors are respectively connected with a point C and a first direct current capacitor Cdc1Negative pole of and second direct current capacitor Cdc2Positive pole, upper clamping switch tube SHAre respectively connected with second direct current capacitors Cdc2Negative pole of and third direct current capacitor Cdc3Positive and lower clamping switch tube SLAre respectively connected with an upper clamping switch tube SHCollector and lower clamping switch tube SLCollector of (1), A phase second follow current switch tube Sa4Collector of (2), B-phase second freewheeling switch tube Sb4Collector and C-phase second freewheeling switch tube Sc4Are respectively connected with the collectors of the A-phase first follow current switch tube Sa3Emitter of and A phase second follow current switch tube Sa4Is connected with the emitting electrode of the B-phase first follow current switch tube Sb3Emitter of and B phase second follow current switch tube Sb4Is connected with the emitting electrode of the C-phase first follow current switch tube Sc3And an emitter electrode ofC-phase second follow current switch tube Sc4Is connected with the emitting electrode of the A-phase filter inductor LfaThe other end of the capacitor (C) is connected with an A-phase filter capacitor (C)faPositive electrode and A phase load RaAre connected respectively, a B-phase filter inductor LfbThe other end of the capacitor (C) is connected with a B-phase filter capacitor (C)fbPositive electrode and B phase load RbAre connected respectively, a C-phase filter inductance LfcThe other end of the capacitor (C) is connected with a C-phase filter capacitor (C)fcPositive electrode and C-phase load RcAre connected with each other, and an A-phase filter capacitor CfaNegative pole of the capacitor and a B-phase filter capacitor CfbNegative pole, C phase filter capacitor CfcNegative electrode of (1), A phase load RaThe other end of (1), B phase load RbAnd the other end of (2) and a C-phase load RcThe other ends of the two are respectively connected with a point N;
the control method comprises the following steps:
the first step is as follows: sine-modulating wave u of A phaseraB phase sine modulation wave urbAnd C phase sine modulation wave urbRespectively at triangular carrier ucIntersecting, obtaining six pre-processing signals u through a comparatora1'、ua2'、ub1'、ub2'、uc1' and uc2'；
The second step is that: dividing the working mode of the non-isolation clamping type three-phase Heric photovoltaic inverter into six non-follow current modes and two follow current modes by judging the preprocessed signals;
the third step: will preprocess the signal ua1'、ub1' and uc1' AND operation to obtain signal ugeL', to preprocess the signal ua2'、ub2' and uc2' AND operation to obtain signal ugeH', to preprocess the signal ua1'、ub1' and uc1Two by two are subjected to same or operation to obtain three signals, and the three signals are subjected to and operation to obtain a signal ut'；
The fourth step: will signal ugeL' sum signal ut' AND operation to obtain the lower clamping switch tube SLDrive signal u ofgeLWill signal ugeH' sum signal ut' AND operation to obtain the upper clamping switch tube SHDrive signal u ofgeHWill signal ugeLSum signal ugeHObtaining a six-way switch tube S of a follow current circuit by OR operationa3、Sa4、Sb3、Sb4、Sc3And Sc4Drive signal u ofge34；
The fifth step: will lower the clamping switch tube SLDrive signal u ofgeLAfter taking the logical negation, respectively comparing with the preprocessed signal ua1'、ub1' and uc1' obtaining the A-phase upper bridge arm switch tube S in sequence after the AND operationa1Drive signal ugea1B phase upper bridge arm switch tube Sb1Drive signal ugeb1And C-phase upper bridge arm switching tube Sc1Drive signal ugec1(ii) a Will clamp the switch tube SHDrive signal u ofgeHAfter taking the logical negation, respectively comparing with the preprocessed signal ua2'、ub2' and uc2' obtaining the A-phase lower bridge arm switch tube S in sequence after the AND operationa2Drive signal ugea2B-phase lower bridge arm switch tube Sb2Drive signal ugeb2And C-phase lower bridge arm switching tube Sc2Drive signal ugec2。
2. The method for controlling the non-isolated clamped three-phase Heric photovoltaic inverter as recited in claim 1, wherein: in the first step, an A-phase sine modulation wave uraB phase sine modulation wave urbAnd C phase sine modulation wave urbThe phase difference is 120 degrees; a phase sine modulation wave uraAnd a triangular carrier ucIntercept, when uraGreater than ucWhen the output is high, when uraLess than ucOutputting low level in time to obtain A-phase upper bridge arm switch tube Sa1Is pre-processeda1', to preprocess the signal ua1' getting logical negation to obtain A-phase lower bridge arm switch tube Sa2Is pre-processeda2' B phase sine modulation wave urbAnd a triangular carrier ucIntercept, when urbGreater than ucWhen the output is high, when urbLess than ucOutputting low level in time to obtain B-phase upper bridge arm switch tube Sb1Pretreatment ofSignal ub1', to preprocess the signal ub1Getting logical negation to obtain B-phase lower bridge arm switch tube Sb2Is pre-processedb2' C phase sine modulation wave urcAnd a triangular carrier ucIntercept, when urcGreater than ucWhen the output is high, when urcLess than ucOutputting low level in time to obtain C-phase upper bridge arm switch tube Sc1Is pre-processedc1', to preprocess the signal uc1' getting logical negation to obtain C-phase lower bridge arm switch tube Sc2Is pre-processedc2'。
3. The method for controlling the non-isolated clamped three-phase Heric photovoltaic inverter as recited in claim 1, wherein: in the second step, when the inverter works in a non-follow current mode, the A-phase upper bridge arm switching tube Sa1Phase A lower bridge arm switch tube Sa2B phase upper bridge arm switch tube Sb1B-phase lower bridge arm switch tube Sb2C-phase upper bridge arm switch tube Sc1And C-phase lower bridge arm switching tube Sc2Switching on and off according to SPWM control mode, and an upper clamping switch tube SHLower clamping switch tube SLAnd follow current circuit six-way switch tube Sa3、Sa4、Sb3、Sb4、Sc3And Sc4Are all in an off state.
4. The method for controlling the non-isolated clamped three-phase Heric photovoltaic inverter as claimed in claim 3, wherein: in the second step, when the inverter works in a non-follow current mode, the A-phase upper bridge arm switching tube Sa1Drive signal ugea1And A phase lower bridge arm switch tube Sa2Drive signal ugea2On the contrary, B phase upper bridge arm switch tube Sb1Drive signal ugeb1And B phase lower bridge arm switch tube Sb2Drive signal ugeb2On the contrary, C-phase upper bridge arm switch tube Sc1Drive signal ugec1And C-phase lower bridge arm switching tube Sc2Drive signal ugec2The opposite is true.
5. The method for controlling the non-isolated clamped three-phase Heric photovoltaic inverter as claimed in claim 3, wherein: in the second step, when the inverter works in a follow current mode, the three-phase bridge arm six switching tubes Sa1、Sa2、Sb1、Sb2、Sc1And Sc2Six-way switch tube S with turn-off and follow current circuitsa3、Sa4、Sb3、Sb4、Sc3And Sc4All conducting, upper and lower clamping switch tubes S of clamping circuitHAnd SLSelectively conducting; the specific scheme of selective conduction is as follows: if A phase upper bridge arm switch tube Sa1Is pre-processeda1' B phase upper bridge arm switch tube Sb1Is pre-processedb1' and C phase upper bridge arm switch tube Sc1Is pre-processedc1' simultaneously high level, the lower clamp switch tube SLConducting if the A-phase lower bridge arm switch tube Sa2Is pre-processeda2' B phase lower bridge arm switch tube Sb2Is pre-processedb2' and C-phase lower bridge arm switch tube Sc2Is pre-processedc2' simultaneously high level, the upper clamping switch tube SHAnd conducting.
6. The control method of the non-isolated clamp type three-phase Heric photovoltaic inverter as claimed in any one of claims 1 to 5, wherein: when the inverter is controlled using this method, its common-mode voltage ucmIs a square wave, the upper peak value of the square wave is 2UPV(ii)/3, lower peak is UPVA frequency is three times of the triangular carrier frequency; the expression for the common mode voltage is:
ucm＝(uAQ+uBQ+uCQ)/3
wherein u isAQIs the potential difference between the A point and the Q point, uBQIs the potential difference between B point and Q point, uCQIs the potential difference between the point C and the point Q.
7. The method for controlling a non-isolated clamped three-phase Heric photovoltaic inverter as claimed in any one of claims 1 to 5, wherein said method comprises: defining the inverter switch state as [ M1,M2,M3,M4,M5]；M1Representing the switching state of the switching tube of the A-phase bridge arm, M11 represents that the switching tube of the upper bridge arm of the A phase is conducted and the switching tube of the lower bridge arm is turned off, and M1When the switching tube of the upper bridge arm of the A phase is turned off and the switching tube of the lower bridge arm is turned on, M is 01Z represents that the switching tubes of the upper and lower bridge arms of the phase A are all turned off; m2Representing the switching state of the B-phase bridge arm switching tube, M21 represents that the switching tube of the upper bridge arm of the B phase is conducted and the switching tube of the lower bridge arm is turned off, and M2When the upper bridge arm switching tube of the B phase is turned off and the lower bridge arm switching tube of the B phase is turned on, M represents that M represents the number of the upper bridge arm switching tubes of the B phase2Z represents that the switching tubes of the upper and lower bridge arms of the B phase are all turned off; m3Representing the switching state of the C-phase bridge arm switching tube, M31 represents that the C-phase upper bridge arm switching tube is conducted and the lower bridge arm switching tube is turned off, and M3When the C-phase upper bridge arm switching tube is turned off and the lower bridge arm switching tube is turned on, M is 03Z represents that the switching tubes of the upper and lower bridge arms of the C phase are all turned off; m4Indicating the switching state of the upper and lower clamping switch tubes of the clamping circuit, M41 means that the upper clamping switch tube is conducted and the lower clamping switch tube is turned off, M4When the upper clamping switch tube is turned off and the lower clamping switch tube is turned on, M is equal to 04Z represents that the upper clamping switch tube and the lower clamping switch tube are both turned off; m5Indicating the switching state of the six switching tubes of the freewheel circuit, M51 indicates that six switching tubes of the follow current circuit are all conducted, M50 represents that the six switching tubes of the follow current circuit are all turned off;
therefore, the 6 non-freewheeling switching modes of the inverter are [1,0,0, Z,0], [1,1,0, Z,0], [0,1,1, Z,0], [0,0,1, Z,0] and [1,0,1, Z,0], respectively, and the 2 freewheeling switching modes are [ Z,1,1] and [ Z,0,1], respectively.
CN201910675252.7A 2019-07-25 2019-07-25 Control method of non-isolated clamping type three-phase Heric photovoltaic inverter Active CN110943637B (en)

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CN106849722A (en) * 2017-03-29 2017-06-13 中南大学 A kind of modified HERIC single-phase inverters
CN106849728A (en) * 2017-03-15 2017-06-13 南京邮电大学 The control method of the Clamp three-phase non-isolated photovoltaic DC-to-AC converter with continued flow switch

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106849728A (en) * 2017-03-15 2017-06-13 南京邮电大学 The control method of the Clamp three-phase non-isolated photovoltaic DC-to-AC converter with continued flow switch
CN106849722A (en) * 2017-03-29 2017-06-13 中南大学 A kind of modified HERIC single-phase inverters

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