CN106411168B - A kind of diode clamping tri-level powder inverter common-mode voltage suppressing method - Google Patents

A kind of diode clamping tri-level powder inverter common-mode voltage suppressing method Download PDF

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CN106411168B
CN106411168B CN201610927655.2A CN201610927655A CN106411168B CN 106411168 B CN106411168 B CN 106411168B CN 201610927655 A CN201610927655 A CN 201610927655A CN 106411168 B CN106411168 B CN 106411168B
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vector
voltage
small vector
operating condition
small
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CN106411168A (en
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吕佃顺
林资旭
张勇波
王贵鹏
张伟华
任晓娜
陈立权
徐铮
李海东
武鑫
许洪华
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Baoding Corona Control Equipment Co ltd
Corona Wind Energy Equipment Beijing Co ltd
Beijing Corona Science and Technology Co Ltd
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BAODING CORONA CONTROL EQUIPMENT Co Ltd
Kenuo Weiye Wind Energy Equipment (beijing) Co Ltd
Beijing Corona Science and Technology Co Ltd
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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
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

A kind of common-mode voltage suppressing method suitable for diode clamping tri-level inverter, it is characterised in that the method will remove positive small vector in vector that output voltage synthesizes, while maintain neutral point voltage balance.Sector cell number where needing output voltage according to inverter, selects basic space vector, includes zero vector, transition small vector, the big vector of middle vector sum.In order to control neutral point voltage balance, two negative small vectors with 120 degree of transition small vector mutual deviation are introduced as the first additional small vector and the second additional small vector.According to transition small vector, the first additional small vector and the corresponding three-phase current of the second additional small vector and mid-point voltage deviation, mid-point voltage control is divided into 3 kinds of operating conditions, calculates the control ability of every kind of operating condition alignment voltage, control ability the maximum is optimum operating condition.Each vector final action time is calculated according to the optimum operating condition of selection, power electronic devices on-off is controlled, output common mode voltage magnitude is reduced to 1/6 DC bus-bar voltage.

Description

A kind of diode clamping tri-level powder inverter common-mode voltage suppressing method
Technical field
The present invention relates to a kind of common-mode voltage suppressing methods suitable for diode clamping tri-level inverter.
Background technique
With the protrusion of energy and environmental problem, more sight are invested renewable energy, apoplexy by countries in the world Power power generation has become the renewable energy power generation mode of current on the largest scaleization exploit condition and commercialized development prospect.In wind In power power generation, PWM frequency converter is needed to handle electric energy, wherein the four-quadrant being made of diode clamping tri-level inverter Current transformer has the advantages that energy conversion efficiency is high, control is relatively easy, du/dt is low etc. and is widely adopted, but applies at it There are some negative effects in journey, typical problem is the high frequency common mode voltage that inverter generates.
High frequency common mode voltage can induce high frequency shaft voltage on alternator shaft, and then form shaft current, corrosion power generation Machine bearing.High frequency common mode voltage and generator windings parasitic capacitance interact, and reduce winding insulation against ground；High frequency common mode simultaneously Voltage generates very strong electromagnetic interference, influences the normal operation of other control systems and electronic equipment.With the raising of voltage, electricity Power equipment is smaller and smaller for the voltage margin of design, it is contemplated that more level blocks are the classical pathway for realizing high voltage, research More level PWM inverter output common mode voltage suppression technologies have important theory significance and practical value.
Document " research of common-mode voltage suppression technology in multilevel SPWM frequency converter " Jiang Yanshu, the such as Xu Dianguo, " mostly electricity The inhibition of flat powder inverter common-mode voltage " Zhao Li, Song Pinggang etc., it proposes to inhibit powder inverter common-mode voltage output using software mode, But do not consider neutral-point voltage balance.And neutral point voltage balance is the base of diode clamping tri-level inverter stable operation Plinth.
Summary of the invention
The purpose of the present invention is overcoming existing common-mode voltage suppressing method not can control neutral point voltage balance, propose A kind of suppressing method reducing diode clamping tri-level inverter output common mode voltage, while reaching common-mode voltage inhibition It can control neutral point voltage balance.
The vector space of diode clamping tri-level inverter is divided into 6 sectors by the present invention, and each sector is subdivided into 2 Cell, midpoint electric current and corresponding phase current direction when being acted on according to small vector, is divided into positive small vector and negative small vector for small vector, Using PWM (NPSVPWM) the Vector modulation strategy for being free of positive small vector, just small arrow is removed in the vector of output voltage synthesis Amount, while maintaining neutral point voltage balance；The negative small vector for participating in output voltage synthesis is divided into transition according to Vector modulation relationship Small vector, the first additional small vector and the second additional small vector, and according to the control of alignment voltage when the effect of different small vectors Ability derives optimum operating condition selection criteria, realizes that alignment voltage effectively controls.The present invention can be by inverter output common mode electricity Pressure amplitude value is reduced to 1/6 DC bus-bar voltage by 1/3 original DC bus-bar voltage.
For diode clamping tri-level inverter, it is made of 12 IGBT and 6 clamp diodes.Use switching variable Sa、Sb、ScEach bridge arm switch state of three-level inverter is respectively indicated, 0,1,2 three state respectively corresponds bridge arm0、Three voltage outputs.The switch state for defining three-level inverter is SaSbSc, then three-level inverter shares 27 switches State respectively corresponds 19 spatialities.
Entire vector space is divided into 6 sectors, each sector is divided into 2 cells, is indicated with (xy), and x represents sector number, Y represents cell id, for example (12) area indicates the 2nd cell of the 1st sector.Vector is divided into 4 classes according to length: zero vector, small vector, in The big vector of vector sum is zero vector positioned at 0 point, and it is small vector that length, which is located at small vector circle, and length is located at middle vector circle For middle vector, it is big vector that length, which is located at big vector circle,.Small vector has 1 redundant state, and zero vector has 2 redundant states. Define three-phase current IabcWith midpoint electric current ImIt is positive with output, if small vector corresponds to midpoint electric current and phase current when acting on Direction is identical, referred to as positive small vector, and such as 100,122；If small vector effect when correspond to midpoint electric current with phase current on the contrary, if claim Be negative small vector, and such as 011,211.
Different vectors correspond to different common-mode voltage amplitudes | VN0|, as shown in table 1.Wherein, UdcFor inverter DC bus electricity Pressure.
Table 1
Wherein, middle vector corresponds to common-mode voltage amplitude | VN0|=0, big vector corresponds to common-mode voltage amplitudeJust Small vector corresponds to common-mode voltage amplitudeNegative small vector corresponds to common-mode voltage amplitudeZero vector 111 Corresponding common-mode voltage amplitude | VN0|=0, the corresponding common-mode voltage amplitude of zero vector 000,222If participating in synthesis The vector state of output voltage does not include 000,222 two zero vector, and inverter output common mode voltage magnitude will be fromIt reduces It arrivesIf removing positive small vector again, inverter output common mode voltage magnitude will be fromIt is reduced toRemoval 000, 222 two zero vectors, remove 6 positive small vectors, and remaining 19 vector positions uniquely correspond to 19 spatialities.
In order to realize the purpose for inhibiting common-mode voltage output, the vector for participating in output voltage synthesis removes two zero vectors 000 and 222, remove 6 positive small vectors.Zero vector 111, negative small vector, middle vector sum 4 bases of big vector are used for each cell Plinth vector participates in output voltage synthesis.The basis vector that each cell participates in output voltage synthesis is as shown in table 2.
Table 2
Vector used in synthesising output voltage is selected, each vector action time is sought.For each on off sequence, in order to Control neutral point voltage balance, the big vector of vector sum in preferential use；Negative small vector distributes the least action time for status transition Tmin, referred to as transition small vector；Zero vector is filled for remaining time.If transition small vector VstIt is T between workst, middle vector VmEffect Time is Tm, big vector VlAction time is Tl, zero vector V0Action time is T0, sector number n.
It defines inverter and needs output voltage UoαβIt is U in α axis componentα, it is U in beta -axis componentβIf maximum vector length isTo each vector according to DC bus-bar voltage UdcIt carries out marking change, middle vectorBig vector
Transition small vector when 1 cell of each sectorWhen calculating each vector effect of the 1st cell Between as shown in formula (1).
When 2 cell of each sector, small vectorCalculate the 2nd cell each vector action time such as formula (2) shown in.
In formula (1) and formula (2), T0For zero vector V0Action time, TstFor transition small vector VstAction time, TmFor middle vector VmAction time, TlFor big vector VlAction time, n is sector number, TminFor the distribution of transition small vector Least action time, VαAnd VβRespectively inverter needs output voltage U0αβIn α axis and beta -axis component.
Each on off sequence includes that a negative small vector is used for status transition, and single negative small vector cumulative function will make midpoint Voltage loses unbalance, it is necessary to introduce other negative small vectors as additional small vector, other two of 120 degree of mutual deviation of introducing bear small Vector is that suitably, one side transition small vector and the two negative small vectors effects introduced respectively correspond different three-phase currents, It can satisfy the real-time control demand of mid-point voltage, on the other hand guarantee that each bridge arm device at most acts one in a PWM cycle It is secondary.Other two negative small vectors of introducing are referred to as the first additional small vector and the second additional small vector by the present invention.Wherein, The additional small vector of vector is named as the first additional small vector in synthesis together with big vector, and 0.5 times is synthesized together with middle vector The additional small vector of big vector is named as the second additional small vector.
The present invention is about transition small vector, the first additional small vector, the definition of the second additional small vector and alignment electricity The control action of pressure, is described in detail by taking (11) cell as an example.
It includes big vector 200, middle vector 210, transition small vector that (11) cell, which participates in output voltage synthesis basis vector, 211 and zero vector 111.In addition, controlling needs according to mid-point voltage, introducing 121 as the first additional small vector or introducing 112 works Participate in output voltage synthesis for the second additional small vector, additional small vector 121 and big vector 200 can synthesize in vector 210, it is attached Add small vector 112 and middle vector 210 that can synthesize 0.5 times big vector 200.
After introducing additional small vector, according to transition small vector Vst, the first additional small vector Vsa1With the second additional small vector Vsa2It acts on corresponding midpoint current symbol and mid-point voltage adjustment direction and the control of alignment voltage is divided into 3 kinds of operating conditions, transition is small Vector adjustment mid-point voltage corresponds to operating condition 1, and the first additional small vector adjustment mid-point voltage corresponds to operating condition 2, the second additional small vector Adjustment mid-point voltage corresponds to operating condition 3.Operating condition 1, operating condition 2, operating condition 3 are described in detail by taking (11) cell as an example.
Operating condition 1: transition small vector acts on corresponding midpoint current symbol and meets mid-point voltage control requirement, adjusts the small arrow of transition Measure action time control mid-point voltage.For (11) cell, big vector 200 is identical as 211 phase of transition small vector, length phase Poor 1 times, transition small vector 211 acts on corresponding midpoint electric current Im=-Ia, 211 effects make mid-point voltage liter when A phase current is output Height, 211 effects reduce mid-point voltage when A phase current is input.The adjustment of 211 alignment voltage of transition small vector is most direct, but It is that can only be controlled toward the direction in half of primitive period.
The additional small vector of operating condition 2: the first effect corresponding current symbol meets mid-point voltage control and requires, and it is additional to increase by first Small vector participates in output voltage synthesis.For (11) cell, the first additional small vector 121 acts on corresponding midpoint electric current Im=- Ib, first adds the effect of small vector 121 and increases mid-point voltage when B phase current is output, and first is additional when B phase current is input The effect of small vector 121 reduces mid-point voltage.Meanwhile 121 synthesize with 200 equal time effects in vector 210, reduce 210 and act on Time, 210 act on corresponding midpoint electric current Im=Ib.Pass through increase-IbAction time reduces IbAction time realizes alignment electricity Press dual regulation effect.
The additional small vector of operating condition 3: the second effect corresponding current symbol meets mid-point voltage control and requires, and it is additional to increase by second Small vector participates in output voltage synthesis.For (11) cell, the second additional small vector 112 acts on corresponding midpoint electric current Im=- Ic, second adds the effect of small vector 112 and increases mid-point voltage when C phase current is output, and second is additional when C phase current is input The effect of small vector 112 reduces mid-point voltage.Meanwhile the time effects such as 112 and middle vector 210 can synthesize 0.5 times of big vector 200,210 action time of vector in increase, 210 act on corresponding midpoint electric current Im=Ib.Pass through increase-IcAction time increases Ib Action time realizes alignment voltage dual regulation effect.
For (11) cell, operating condition 1 is corresponding to increase by 211 action time of transition small vector, realizes A phase current alignment electricity Press control action；Operating condition 2 is corresponding to increase by the first additional 121 action time of small vector, and 210 action time of vector in reduction realizes B The effect of phase current alignment voltage dual regulation；Operating condition 3 is corresponding to increase by the second additional 112 action time of small vector, swears in increase It measured for 210 action times, realizes the effect of C, B biphase current alignment voltage dual regulation.3 kinds of operating conditions respectively correspond 3 phase currents, lead to It crosses and adjusts negative small vector, middle vector action time, realize the real-time control of three-phase current alignment voltage.
The rest may be inferred for other cells, summarizes as shown in table 3, and electric current is corresponding midpoint electric current feelings when vector acts in bracket Condition.
Table 3
Cell Transition small vector First additional small vector Second additional small vector Middle vector
11 211(-Ia) 121(-Ib) 112(-Ic) 210(Ib)
12 110(-Ic) 101(-Ib) 011(-Ia) 210(Ib)
21 110(-Ic) 011(-Ia) 101(-Ib) 120(Ia)
22 121(-Ib) 211(-Ia) 112(-Ic) 120(Ia)
31 121(-Ib) 112(-Ic) 211(-Ia) 021(Ic)
32 011(-Ia) 110(-Ic) 101(-Ib) 021(Ic)
41 011(-Ia) 101(-Ib) 110(-Ic) 012(Ib)
42 112(-Ic) 121(-Ib) 211(-Ia) 012(Ib)
51 112(-Ic) 211(-Ia) 121(-Ib) 102(Ia)
52 101(-Ib) 011(-Ia) 110(-Ic) 102(Ia)
61 101(-Ib) 110(-Ic) 011(-Ia) 201(Ic)
62 211(-Ia) 112(-Ic) 121(-Ib) 201(Ic)
After increasing mid-point voltage control strategy, each vector action time will change on the basis of formula (1) and formula (2), Define Tsa'、T0'、Tst'、Tm'、Tl' it is respectively additional small vector Vsa, zero vector V0, transition small vector Vst, middle vector Vm, big arrow Measure VlFinal action time.
When controlling mid-point voltage using transition small vector, each vector final action time is as shown in formula (3):
When using the first additional small vector control mid-point voltage, each vector final action time is as shown in formula (4):
When using the second additional small vector control mid-point voltage, each vector final action time is as shown in formula (5).
Formula (3), formula (4), in formula (5), Tsa′、T0′、Tst′、Tm′、Tl' it is respectively attached after considering neutral-point voltage balance Add small vector Vsa, zero vector V0, transition small vector Vst, middle vector Vm, greatly swear VlFinal action time is measured, it is wherein attached when operating condition 2 Add small vector VsaCorresponding first additional small vector Vsa1, additional small vector V when operating condition 3saCorresponding second additional small vector Vsa2；T0、 Tst、Tm、TlRespectively using the zero vector V being calculated before mid-point voltage control by formula (1) or formula (2)0, transition small vector Vst, middle vector Vm, big vector VlAction time, TminFor the least action time of transition small vector distribution, K is according to midpoint electricity Deviation PI closed loop is pressed to adjust output quantity.
As can be seen that when the different operating conditions in three kinds of operating conditions of selection act on, each vector is made for analysis mode (3), formula (4), formula (5) It will be changed with the time, the adjustment of different resultant vectors is by occupying zero vector action time T0To realize.Operating condition 1, operating condition 2, operating condition 3 is acted on is respectively to the holding time of zero vectorK(T0-Tmin) and K (T0-Tmin).List is to zero Vector holding time angle considers, is 2 times of operating condition 1 using the cost that operating condition 2 or operating condition 3 adjust mid-point voltage.Meanwhile small arrow It is directly proportional to act on corresponding size of current to vector for the control ability of amount or middle vector alignment voltage.
The standard of analysis selection optimal operating condition equally by taking (11) cell as an example.In (11) cell, the small arrow of transition The effective object of amount, the first additional small vector and the second additional small vector respectively corresponds as A phase current ia, B phase current ibWith C phase Electric current ic, the adjustment characteristic of alignment voltage and zero vector time occupy relationship when in conjunction with the effect of different operating conditions, define different works The control ability of condition alignment voltage is e, as shown in formula (6):
In formula (6), e1、e2、e3Respectively operating condition 1, operating condition 2, the control ability of 3 alignment voltage of operating condition, wherein operating condition 1 The control ability e of alignment voltage1Taking 2 multiplying factors because of operating condition 1 is operating condition 2 or operating condition 3 to zero vector holding time The control ability e of 2 alignment voltage of operating condition2Two electric current i of middle appearancebIncrease by the first additional small vector effect when being because of operating condition 2 B phase current, sign (Δ U are all corresponded to vector effect in reductionneut) it is mid-point voltage symbol.The meaning of formula (6) is in Point voltage sign and vector action characteristic obtain alignment voltage control capability e when the effect of different operating conditions, and control ability e includes e1、e2And e3, e1Corresponding operating condition 1, e2Corresponding operating condition 2, e3Corresponding operating condition 3.Wherein control ability e the maximum alignment voltage controls Ability is most strong, for the optimum condition for adjusting mid-point voltage.
Specific step is as follows by the present invention:
Step 1: entire 360 degree of vector spaces of diode clamping tri-level inverter being divided according to angle, often 60 degree are a sector, are divided into 6 sectors, and number is followed successively by 1~6；60 degree of each sector space carries out carefully again according to angle Point, preceding 30 degree of spaces are the 1st cell, and rear 30 degree of spaces are the 2nd cell.Entire vector space is divided into 12 cells.According to inverse Become device and needs output voltage UoαβIdentify sector and cell number.Specific method: output voltage U is needed to inverteroαβIn α axis and Beta -axis component UαAnd UβIt seeks arc tangent and obtains vector space angle, θ, vector space angle, θ rounds up divided by 60 as sector Number；Remainder is the 1st cell less than 30 degree simultaneously, and it is the 2nd cell that remainder, which is more than or equal to 30 degree,.Such as when vector space angle, θ is At 70 degree, rounding up divided by 60 is 2, and sector number 2, remainder 10 is less than 30, cell id 1.
Step 2: output voltage U is needed according to inverteroαβPlace sector cell number, selection participate in output voltage synthesis Basic space vector, the basic space vector include zero vector V0, transition small vector Vst, middle vector VmWith big vector Vl。 By taking (11) cell as an example, basic space vector includes zero vector 111, transition small vector 211, middle vector 210 and big vector 200；
Step 3: output voltage U is needed according to inverteroαβPlace sector cell number, calculates according to formula (1) and formula (2) Zero vector V0, transition small vector Vst, middle vector Vm, big vector VlAction time, be denoted as T respectively0、Tst、TmAnd Tl；
Step 4: in order to realize mid-point voltage UneutBalance control, needs output voltage U according to inverteroαβPlace sector Cell number, will be with transition small vector VstSpatial position differs 120 degree of two negative small vectors as the first additional small vector Vsa1 With the second additional small vector Vsa2.Wherein, with the big vector V in basis vectorlVector V in common synthesismAdditional small vector life Entitled first additional small vector Vsa1, with the middle vector V in basis vectormCommon synthesis vector V 0.5 times biglAdditional small vector It is named as the second additional small vector Vsa2.By taking (11) cell as an example, 121 with big vector 200 can synthesize in vector 210, referred to as First additional small vector Vsa1, 112 can synthesize 0.5 times big vector 200, the referred to as second additional small vector V with middle vector 210sa2。
Step 5: output voltage U is needed according to inverteroαβPlace sector cell number, referring to transition small vector Vst, first Additional small vector Vsa1With the second additional small vector Vsa2Corresponding three-phase current IabcWith mid-point voltage UneutDeviation, according to formula (6) The control ability e of 3 kinds of operating condition alignment voltage is calculated, control ability e includes e1、e2And e3, e1Corresponding operating condition 1, e2Corresponding operating condition 2, e3Corresponding operating condition 3.Select control ability e the maximum for optimized operation operating condition.
Step 6: the basic space vector selected according to step 2, the additional small vector that step 4 selects, step 5 select most Excellent operating condition, each basis vector action time that step 3 calculates, it is final to substitute into formula (3), formula (4) or each vector of formula (5) calculating Action time generates on off sequence, controls corresponding power electronic devices on-off, realizes final voltage control.
The advantage of the invention is that by the way of software optimization output voltage blended space vector action time, by two poles Pipe clamped three-level inverter output common mode voltage magnitude is reduced to 1/6 DC bus electricity by 1/3 original DC bus-bar voltage Pressure is realized under the premise of not increasing device hardware cost and inhibits powder inverter common-mode voltage output, reduces common-mode voltage to other The harm of equipment.
Detailed description of the invention
Fig. 1 diode clamping tri-level topology；
Fig. 2 three-level inverter space vector divides；
Fig. 3 (11) cell adds small vector and the mutual compositive relation of other vectors；
Fig. 4 diode clamping tri-level powder inverter common-mode voltage inhibits tactful block diagram.
Specific embodiment
The present invention is further illustrated below in conjunction with the drawings and specific embodiments.
Diode clamping tri-level inverter topology is as shown in Figure 1.Inverter acquires positive and negative direct current busbar voltage, remembers respectively For UdcPAnd UdcN；Three-phase alternating current is acquired, I is denoted asabc, wherein A phase, B phase, C phase respectively corresponds Ia、IbAnd Ic；To positive direct-current Busbar voltage UdcPWith negative DC bus-bar voltage UdcNSummation, obtains DC bus-bar voltage Udc；To positive pole line voltage UdcPWith negative direct current Busbar voltage UdcNIt makes the difference, obtains mid-point voltage deviation delta Uneut。
Inverter uses vector control method, 10 in Fig. 1 shown in vector control module output inverter need output voltage Uoαβ.The present invention is as shown in Figure 4 for diode clamping tri-level powder inverter common-mode voltage suppressing method:
Step 1: entire vector space being divided for 360 degree according to angle, every 60 degree are a sector, are divided into 6 Sector, number are 1~6 according to this；60 degree of each sector space is finely divided again according to angle, and preceding 30 degree of spaces are the 1st cell, after 30 degree of spaces are the 2nd cell, and entire vector space is divided into 12 cells, as shown in Figure 2.Output voltage is needed according to inverter Uoαβ, sector and cell number are identified, as shown in 110 in Fig. 4.Specific method: to inverter output voltage UoαβIn α axis and β axis Component UαAnd UβIt seeks arc tangent and obtains vector space angle, θ, vector space angle, θ rounds up divided by 60 as sector number；Together When remainder less than 30 degree be the 1st cell, remainder be more than or equal to 30 degree be the 2nd cell.Such as when vector space angle, θ is 70 degree When, asking whole upwards is 2, sector number 2, and remainder 10 is less than 30, cell id 1.
Step 2: output voltage U being needed according to inverter according to 110 parts in Fig. 4oαβThe sector cell of identification is numbered, choosing The basic space vector for participating in output voltage synthesis is selected, the basic space vector includes zero vector V0, transition small vector Vst、 Middle vector VmWith big vector Vl, as shown in 120 in Fig. 4.By taking (11) cell as an example, basic space vector include zero vector 111, Transition small vector 211, middle vector 210 and big vector 200；
Step 3: output voltage U being needed according to inverter according to 110 parts in Fig. 4oαβThe sector cell of identification is numbered, will DC voltage Udc, inverter need output voltage UoαβIt brings formula (1) (2) into and calculates zero vector V0, transition small vector Vst, middle arrow Measure VmWith big vector VlAction time is denoted as T respectively0、Tst、TmAnd Tl, as shown in 150 in Fig. 4；
Step 4: in order to realize mid-point voltage UneutBalance control, needs to export according to 110 parts in Fig. 4 according to inverter Voltage UoαβThe sector cell of identification is numbered, and the first additional small vector V is selecteda1With the second additional small vector 2Va2, as 130 in Fig. 4 It is shown.Wherein, the additional small vector of vector is named as the first additional small vector in synthesis together with the big vector in basis vector Va1, the additional small vector that 0.5 times big vector is synthesized together with the middle vector in basis vector is named as the second additional small vector Va2.By taking (11) cell as an example, 121 with big vector 200 can synthesize in vector 210, the referred to as first additional small vector Vsa1, 112 0.5 times big vector 200, the referred to as second additional small vector V can be synthesized with middle vector 210sa2, compositive relation is as shown in Figure 3.
Step 5: output voltage U being needed according to inverter according to 110 parts in Fig. 4oαβThe sector cell of identification is numbered, ginseng According to transition small vector Vst, the first additional small vector Va1With the second additional small vector Va2Corresponding three-phase current IabcAnd mid-point voltage UneutDeviation, the control ability e of 3 kinds of operating condition alignment voltage is calculated according to formula (6), and control ability e includes e1、e2And e3, e1It is right Answer operating condition 1, e2Corresponding operating condition 2, e3Corresponding operating condition 3.Select control ability e the maximum for optimized operation operating condition, such as 140 institute in Fig. 4 Show.
Step 6: according to the basis vector of 120 parts selection in step 2, the selection of 130 parts adds small arrow in step 4 It measures, the optimized operation operating condition of 140 parts selection in step 5, each basis vector action time that 150 parts calculate in step 3, band Enter formula (3), (4) or (5) and calculate each vector final action time, produce on off sequence, controls corresponding power electronic devices on-off, The contravarianter voltage output needed is realized, as shown in 160 in Fig. 4.

Claims (5)

1. a kind of diode clamping tri-level powder inverter common-mode voltage suppressing method, it is characterised in that: the method is by two poles The vector space of pipe clamped three-level inverter is divided into 6 sectors, and each sector is subdivided into 2 cells, is acted on according to small vector Shi Zhongdian electric current and corresponding phase current direction, are divided into positive small vector and negative small vector for small vector, using without positive small vector PWM Vector modulation strategy removes positive small vector in the vector of output voltage synthesis, realizes the mesh for reducing common-mode voltage output 's；In order to maintain neutral point voltage balance, the negative small vector for participating in output voltage synthesis is divided into transition according to Vector modulation relationship Small vector, the first additional small vector and the second additional small vector；First additional small vector is defined as together with big vector in synthesis The additional small vector of vector, the second additional small vector are defined as synthesizing the additional small vector of 0.5 times big vector together with middle vector； Transition small vector, the first additional small vector and the second additional small vector are spatially 120 degree of mutual deviation of negative small vector, when effect in Point electric current respectively corresponds three-phase current；Transition small vector, the first additional small vector and the second additional small vector adjust mid-point voltage Corresponding three kinds of different operating conditions, every kind of operating condition pass through increase corresponding negative small vector action time, it is real to reduce zero vector action time It is existing；According to corresponding midpoint size of current when occupying zero vector action time length and acting on, transition small vector, first add it is small The control ability of alignment voltage is different when vector sum second adds small vector effect, select the strongest operating condition of control ability as Optimum operating condition, alignment voltage control effectively.
2. diode clamping tri-level powder inverter common-mode voltage suppressing method according to claim 1, it is characterised in that institute The step of stating method is as follows:
Step 1, entire 360 degree of vector spaces of diode clamping tri-level inverter are divided according to angle, every 60 degree For a sector, 6 sectors are divided into, number is followed successively by 1~6；60 degree of each sector space is finely divided again according to angle, preceding 30 degree of spaces are the 1st cell, and rear 30 degree of spaces are the 2nd cell；Entire vector space is divided into 12 cells；According to inverter need Want output voltage UoαβIdentify sector and cell number, specifically: output voltage U is needed to inverteroαβIn α axis and beta -axis component UαAnd UβIt seeks arc tangent and obtains vector space angle, θ, vector space angle, θ rounds up divided by 60 as sector number；Simultaneously Remainder is the 1st cell less than 30 degree, and it is the 2nd cell that remainder, which is more than or equal to 30 degree,；
Step 2, output voltage U is needed according to inverteroαβPlace sector cell number, selection participate in the base of output voltage synthesis Plinth space vector, the basic space vector include zero vector V0, transition small vector Vst, middle vector VmWith big vector Vl；
Step 3, output voltage U is needed according to inverteroαβPlace sector cell number, calculates zero vector V0, transition small vector Vst, middle vector Vm, big vector VlAction time, be denoted as T respectively0、Tst、TmAnd Tl；
Step 4, in order to realize mid-point voltage UneutBalance control, needs output voltage U according to inverteroαβIt compiles place sector cell Number, it will be with transition small vector VstSpatial position differs 120 degree of two negative small vectors as the first additional small vector Vsa1With second Additional small vector Vsa2；Wherein, with the big vector V in basis vectorlVector V in common synthesismAdditional small vector be named as One additional small vector Vsa1, with the middle vector V in basis vectormCommon synthesis vector V 0.5 times biglAdditional small vector be named as Second additional small vector Vsa2；
Step 5, output voltage U is needed according to inverteroαβPlace sector cell number, referring to transition small vector Vst, it is first additional Small vector Vsa1With the second additional small vector Vsa2Corresponding three-phase current IabcWith mid-point voltage UneutDeviation calculates 3 kinds of operating conditions pair The control ability e of mid-point voltage, control ability e include e1、e2And e3, wherein e1Corresponding operating condition 1, e2Corresponding operating condition 2, e3Corresponding work Condition 3；Select control ability e the maximum for optimized operation operating condition；
Step 6, the basic space vector selected according to step 2, the additional small vector that step 4 selects, the optimal fortune that step 5 selects Row operating condition, each basis vector action time that step 3 calculates calculate each vector final action time, generate on off sequence, control Corresponding power electronic devices on-off realizes the output of inverter required voltage.
3. diode clamping tri-level powder inverter common-mode voltage suppressing method according to claim 2, it is characterised in that institute It states step 3 and calculates zero vector V0, transition small vector Vst, middle vector Vm, big vector VlAction time carried out according to following formula:
Each vector action time is as shown in formula (1) when 1 cell of each sector:
Each vector action time is as shown in formula (2) when 2 cell of each sector:
In formula, T0For zero vector V0Action time, TstFor transition small vector VstAction time, TmFor middle vector VmEffect Time, TlFor big vector VlAction time, n is sector number, TminFor the least action time of transition small vector distribution, UαAnd Uβ Respectively inverter needs output voltage U0αβIn the component of α axis and β axis.
4. diode clamping tri-level powder inverter common-mode voltage suppressing method according to claim 2, it is characterised in that: institute The step 5 stated calculates the control ability e of three kinds of operating condition alignment voltage, and control ability e includes e1、e2And e3, wherein e1Corresponding work Condition 1, e2Corresponding operating condition 2, e3Corresponding operating condition 3；Select control ability e the maximum as follows for the method for optimized operation operating condition；
According to transition small vector Vst, the first additional small vector Vsa1With the second additional small vector Vsa2Act on corresponding midpoint current symbol The control of alignment voltage is divided into 3 kinds of operating conditions with mid-point voltage adjustment direction；
Operating condition 1: transition small vector acts on corresponding midpoint current symbol and meets mid-point voltage control requirement, and adjustment transition small vector is made Mid-point voltage is controlled with the time；
The additional small vector of operating condition 2: the first effect corresponding current symbol meets mid-point voltage control and requires, and increases by first and adds small arrow Amount participates in output voltage synthesis；
The additional small vector of operating condition 3: the second effect corresponding current symbol meets mid-point voltage control and requires, and increases by second and adds small arrow Amount participates in output voltage synthesis；
The adjustment characteristic of alignment voltage and zero vector time occupy relationship when in conjunction with the effect of different operating conditions, define different operating conditions pair The control ability of mid-point voltage is e, as shown in formula (6):
In formula (6), e1、e2、e3Respectively operating condition 1, operating condition 2, the control ability of 3 alignment voltage of operating condition, ia、ibAnd icFor three-phase Alternating current, wherein the control ability e of 1 alignment voltage of operating condition1Taking 2 multiplying factors is because operating condition 1 is to zero vector holding time It is operating condition 2 or operating condition 3The control ability e of 2 alignment voltage of operating condition2Two electric current i of middle appearancebIncreasing when being because of operating condition 2 Vector effect all corresponds to B phase current, sign (Δ U in adding the first additional small vector effect and reducingneut) it is mid-point voltage symbol； The meaning of formula (6) is that alignment voltage controls energy when obtaining the effect of different operating conditions according to mid-point voltage symbol and vector action characteristic Power e, wherein e1Corresponding operating condition 1, e2Corresponding operating condition 2, e3Corresponding operating condition 3；Control ability e the maximum alignment voltage control capability It is most strong, for the optimum condition for controlling mid-point voltage.
5. diode clamping tri-level powder inverter common-mode voltage suppressing method according to claim 2, it is characterised in that: institute The method that the step 6 stated calculates each vector final action time is as follows:
The optimized operation work selected according to the additional small vector that the basic space vector that step 2 selects, step 4 select, step 5 Condition, each basis vector action time that step 3 calculates substitute into formula (3), formula (4) or formula (5), when calculating each vector and finally acting on Between；
When controlling mid-point voltage using transition small vector, each vector final action time is as shown in formula (3):
When using the first additional small vector control mid-point voltage, each vector final action time is as shown in formula (4):
When using the second additional small vector control mid-point voltage, each vector final action time is as shown in formula (5):
Formula (3), formula (4), in formula (5), T 'sa、T’0、T’st、T’m、T’lIt is respectively added after consideration neutral-point voltage balance small Vector Vsa, zero vector V0, transition small vector Vst, middle vector Vm, greatly swear VlFinal action time is measured, is wherein added when operating condition 2 small Vector VsaCorresponding first additional small vector Vsa1, additional small vector V when operating condition 3saCorresponding second additional small vector Vsa2；T0、Tst、 Tm、TlRespectively using the zero vector V being calculated before mid-point voltage control by formula (1) or formula (2)0, transition small vector Vst, in Vector Vm, big vector VlAction time, TminFor the least action time of transition small vector distribution, K is according to mid-point voltage deviation PI closed loop adjusts output quantity.
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