CN106411168A - Diode clamp three-level inverter common-mode voltage suppression method - Google Patents

Abstract

The present invention provides a common-mode voltage suppression method applicable for a diode clamp three-level inverter. The method is configured to remove the positive small vectors in the vectors synthesized by output voltage and maintain the neutral-point voltage balance. The community numbers of a section where the voltage are located is outputted according to the inverter requirement, and the basic space vectors are selected, wherein the space vectors comprise zero vectors, transition small vectors, medium vectors and big vectors. In order to control the neutral-point voltage balance, two negative small vectors having 120-degree mutual difference from the transition small vectors are taken as a first additional small vector and a second additional small vector. According to the three-phase current and the neutral-point voltage deviation corresponding to the transition small vectors, the first additional small vector and the second additional small vector, the neutral-point voltage is divided into three work conditions, the control capacity of the neutral-point voltage of each work condition is calculated, and the work condition with the biggest control capacity is the optimal work condition. According to the selected optimal work condition, the final action time of each vector is calculated, the switching of a power electronic device is controlled, and the outputted common-mode voltage amplitude is reduced to the 1/6 direct current bus 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 method being applied to diode clamping tri-level inverter.

Background technology

Prominent with the energy and environmental problem, regenerative resource, its apoplexy are invested more sight in countries in the world Power generates electricity and has become as the renewable energy power generation mode of on the largest scaleization exploit condition and commercialized development prospect at present.In wind During power generates electricity, need PWM converter that electric energy is processed, the four-quadrant being wherein made up of diode clamping tri-level inverter Current transformer has that energy conversion efficiency is high, it is relatively easy to control, the low advantage of du/dt is widely adopted, but should be used at it There are some negative effects, the high frequency common mode voltage that typical problem produces for inverter in journey.

High frequency common mode voltage can induce high frequency shaft voltage on alternator shaft, and then forms shaft current, and corrosion generates electricity Machine bearing.High frequency common mode voltage is interacted with generator windings parasitic capacitance, reduces winding insulation against ground；High frequency common mode simultaneously Voltage produces very strong electromagnetic interference, the normal operation of the other control system of impact and electronic equipment.With the rising of voltage, electricity Power equipment be available for design voltage margin less and less it is contemplated that many level block are to realize high-tension classical pathway, research Many level PWMs inverter output common mode voltage suppression technology has important theory significance and practical value.

Document《The research of common-mode voltage suppression technology in multilevel SPWM converter》Jiang Yanshu, Xu Dianguo etc.,《How electric The suppression of flat powder inverter common-mode voltage》Zhao Li, Song Pinggang etc., propose using software mode suppression powder inverter common-mode voltage output, But all do not consider neutral-point voltage balance.And neutral point voltage balance is the base of diode clamping tri-level inverter stable operation Plinth.

Content of the invention

The purpose of the present invention is the shortcoming overcoming existing common-mode voltage suppressing method can not control neutral point voltage balance, proposes A kind of suppressing method reducing diode clamping tri-level inverter output common mode voltage, while reaching common-mode voltage suppression Neutral point voltage balance can be controlled.

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, when being acted on according to small vector, midpoint electric current and corresponding phase current direction, small vector is divided into positive small vector and negative small vector, Using PWM (NPSVPWM) the Vector modulation strategy without positive small vector, in the vector of output voltage synthesis, remove just little arrow Amount, maintains neutral point voltage balance simultaneously；The negative small vector participating in output voltage synthesis is divided into transition according to Vector modulation relation Small vector, the first additional small vector and the second additional small vector, and when being acted on according to different small vectors centering point voltage control Ability derives optimum operating condition selection standard, realizes centering point voltage effective control.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 up of 12 IGBT and 6 clamp diodes.Use switching variable S_a、S_b、S_cRepresent three-level inverter each brachium pontis on off state respectively, 0,1,2 three states correspond to brachium pontis respectively Three voltage outputs.The on off state defining three-level inverter is S_aS_bS_c, then three-level inverter have 27 On off state, corresponds to 19 spatialities respectively.

Whole vector space is divided into 6 sectors, each sector is divided into 2 cells, is represented with (xy), x represents sector number, Y represents cell id, and such as (12) area represents the 1st sector the 2nd cell.Vector is divided into 4 classes according to length：Zero vector, small vector, in The big vector of vector, is zero vector positioned at 0 point, and length is small vector positioned at small vector circle, and length is located at middle vector circle For middle vector, length is big vector positioned at big vector circle.Small vector has 1 redundant state, and zero vector has 2 redundant states. Define three-phase current I_abcWith midpoint electric current I_mAll to be just output as, if corresponding midpoint electric current and phase current during small vector effect Direction is identical, referred to as positive small vector, and such as 100,122；If corresponding midpoint electric current is contrary with phase current during small vector effect, claim For bearing small vector, such as 011,211.

Different vectors corresponding difference common-mode voltage amplitude | V_N0|, as shown in table 1.Wherein, U_dcFor inverter dc bus electricity Pressure.

Table 1

Wherein, middle vector corresponds to common-mode voltage amplitude | V_N0|=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 | V_N0|=0, zero vector 000,222 corresponds to common-mode voltage amplitudeIf participating in synthesis The vector state of output voltage does not comprise 000,222 two zero vectors, and inverter output common mode voltage magnitude will be fromReduce ArriveIf 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 of suppression common mode voltage output, the vector participating in output voltage synthesis removes two zero vectors 000 and 222, remove 6 positive small vectors.Zero vector 111, negative small vector, 4 bases of the big vector of middle vector are adopted 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

Select the vector used by synthesising output voltage, ask for each vector action time.For each on off sequence, in order to Control neutral point voltage balance, the big vector of vector in preferentially adopting；Negative small vector is used for status transition and distributes the least action time T_min, referred to as transition small vector；Zero vector is used for filling remaining time.If transition small vector V_stIt is T between work_st, middle vector V_mEffect Time is T_m, big vector V_lAction time is T_l, zero vector V₀Action time is T₀, sector number is n.

Defining inverter needs output voltage U_oαβIt is U in α axle component_α, it is U in beta -axis component_βIf maximum vector length isTo each vector according to DC bus-bar voltage U_dcCarry out standardization, middle vectorBig vector

Transition small vector during 1 cell of each sectorWhen calculating the effect of the 1st cell each vector Between as shown in formula (1).

During 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, T_stFor transition small vector V_stAction time, T_mFor middle vector V_mAction time, T_lFor big vector V_lAction time, n be sector number, T_minFor the distribution of transition small vector The least action time, V_αAnd V_βBeing respectively inverter needs output voltage U_0αβIn α axle and beta -axis component.

Each on off sequence comprises a negative small vector 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, the other two introducing 120 degree of mutual deviation is negative little Vector is suitable, and one side transition small vector and the two negative small vector effects introducing correspond to different three-phase currents respectively, Can meet the real-time control demand of mid-point voltage, on the other hand ensure the most action one of each brachium pontis device in a PWM cycle Secondary.Two negative small vectors of other that the present invention is introduced into are referred to as the first additional small vector and the second additional small vector.Wherein, In synthesizing together with big vector, the additional small vector of vector is named as the first additional small vector, synthesizes 0.5 times together with middle vector The additional small vector of big vector is named as the second additional small vector.

The present invention is with regard to transition small vector, the first additional small vector, the definition of the second additional small vector and alignment electricity The control action of pressure, taking (11st) cell is as a example described in detail.

(11st) cell participates in output voltage synthesis basis vector and comprises big vector 200, middle vector 210, transition small vector 211 and zero vector 111.In addition, needs are controlled according to mid-point voltage, introduce 121 as the first additional small vector or introduce 112 works Participate in output voltage synthesis for the second additional small vector, additional small vector 121 can synthesize with big vector 200 in vector 210, attached Plus small vector 112 can synthesize 0.5 times of big vector 200 with middle vector 210.

After introducing additional small vector, according to transition small vector V_st, the first additional small vector V_sa1With the second additional small vector V_sa2The control of centering point voltage is divided into 3 kinds of operating modes by the corresponding midpoint current symbol of effect and mid-point voltage adjustment direction, transition Small vector adjustment mid-point voltage corresponds to operating mode 1, and the first additional small vector adjustment mid-point voltage corresponds to operating mode 2, and second adds little arrow Amount adjustment mid-point voltage corresponds to operating mode 3.Taking (11st) cell as a example operating mode 1, operating mode 2, operating mode 3 are described in detail.

Operating mode 1：Transition small vector effect corresponding midpoint current symbol meets mid-point voltage and controls requirement, adjusts the little arrow of transition Amount controls mid-point voltage action time.For (11st) cell, big vector 200 is identical with transition small vector 211 phase place, length phase Differ from 1 times, the corresponding midpoint electric current I of transition small vector 211 effect_m=-I_a, A phase current is that during output, 211 effects make mid-point voltage liter Height, A phase current is that during input, 211 effects make mid-point voltage reduce.Transition small vector 211 alignment Voltage Cortrol is the most direct, but It is can only to control toward the direction in half primitive period.

Operating mode 2：First additional small vector effect corresponding current symbol meets mid-point voltage and controls requirement, increases by first and adds Small vector participates in output voltage synthesis.For (11st) cell, the first additional small vector 121 effect corresponds to midpoint electric current I_m=- I_b, B phase current is that during output, the first additional small vector 121 effect makes mid-point voltage raise, and B phase current adds for during input first Small vector 121 effect makes mid-point voltage reduce.Meanwhile, vector 210 in the time effect synthesis such as 121 and 200, reduces by 210 effects Time, the corresponding midpoint electric current I of 210 effects_m=I_b.By increase-I_bAction time, reduce I_bAction time, realize alignment electricity Pressure dual regulation effect.

Operating mode 3：Second additional small vector effect corresponding current symbol meets mid-point voltage and controls requirement, increases by second and adds Small vector participates in output voltage synthesis.For (11st) cell, the second additional small vector 112 effect corresponds to midpoint electric current I_m=- I_c, C phase current is that during output, the second additional small vector 112 effect makes mid-point voltage raise, and C phase current adds for during input second Small vector 112 effect makes mid-point voltage reduce.Meanwhile, 112 can synthesize 0.5 times of big vector with middle vector 210 grade time effect 200, vector 210 action time in increase, the corresponding midpoint electric current I of 210 effects_m=I_b.By increase-I_cAction time, increase I_b Realize centering point voltage dual regulation effect action time.

For (11st) cell, operating mode 1 is corresponding to increase transition small vector 211 action time, realizes A phase current alignment electricity Pressure control action；Operating mode 2 is corresponding to increase by first additional small vector 121 action time, and in minimizing, vector 210 action time, realizes B Phase current centering point voltage dual regulation acts on；Operating mode 3 is corresponding to increase by second additional small vector 112 action time, swears in increase Measured for 210 action times, realize the effect of C, B biphase current centering point voltage dual regulation.3 kinds of operating modes correspond to 3 phase currents respectively, lead to Spend the negative small vector of adjustment, middle vector action time, realize the real-time control of three-phase current centering point voltage.

The rest may be inferred for other cells, summarizes as shown in table 3, electric current corresponding midpoint electric current feelings when acting on for vector 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 will change action time on the basis of formula (1) and formula (2), Define T_sa'、T₀'、T_st'、T_m'、T_l' it is respectively additional small vector V_sa, zero vector V₀, transition small vector V_st, middle vector V_m, big swear Amount V_lFinal action time.

When controlling mid-point voltage using transition small vector, each vector final action time is as shown in formula (3)：

When controlling mid-point voltage using the first additional small vector, each vector final action time is as shown in formula (4)：

When controlling mid-point voltage using the second additional small vector, each vector final action time is as shown in formula (5).

In formula (3), formula (4), formula (5), T_sa’、T₀’、T_st’、T_m’、T_l' be respectively consider neutral-point voltage balance after attached Plus small vector V_sa, zero vector V₀, transition small vector V_st, middle vector V_m, greatly swear V_lMeasure attached during final action time, wherein operating mode 2 Plus small vector V_saCorresponding first additional small vector V_sa1, additional small vector V during operating mode 3_saCorresponding second additional small vector V_sa2；T₀、 T_st、T_m、T_lIt is respectively before adopting mid-point voltage to control by formula (1) or the calculated zero vector V of formula (2)₀, transition small vector V_st, middle vector V_m, big vector V_lAction time, T_minThe least action time distributed for transition small vector, K is according to midpoint electricity Pressure deviation PI closed loop adjusts output.

Analysis mode (3), formula (4), formula (5) are as can be seen that when selecting the different operating mode effect in three kinds of operating modes, each vector is made To be changed with the time, the adjustment of different resultant vectors is passed through to take zero vector T action time₀To realize.Operating mode 1, operating mode 2nd, operating mode 3 acts on the holding time to zero vector and is respectivelyWith K (T₀-T_min).Dan Cong Zero vector holding time angle is considered, is 2 times of operating mode 1 using the cost that operating mode 2 or operating mode 3 adjust mid-point voltage.Meanwhile, Small vector or the control ability of middle vector centering point voltage, act on corresponding size of current with vector and are directly proportional.

The standard of same taking (11st) cell as a example analysis selection optimal operating condition.In (11st) cell, the little arrow of transition The effective object of amount, the first additional small vector and the second additional small vector corresponds to A phase current i respectively_a, B phase current i_bWith C phase Electric current i_c, when acting in conjunction with different operating modes, the adjustment characteristic of centering point voltage and zero vector time take relation, the different work of definition The control ability of condition centering point voltage is e, as shown in formula (6)：

In formula (6), e₁、e₂、e₃It is respectively operating mode 1, operating mode 2, the control ability of operating mode 3 centering point voltage, wherein operating mode 1 Control ability e of centering point voltage₁2 multiplying factors are taken to be because that operating mode 1 is operating mode 2 or operating mode 3 to zero vector holding time Control ability e of operating mode 2 centering point voltage₂Two electric current i of middle appearance_bIt is because during operating mode 2 increasing by the first additional small vector effect All correspond to B phase current, sign (Δ U with vector effect in reduction_neut) it is mid-point voltage symbol.The implication of formula (6) is in basis Point voltage symbol and vector action characteristic obtain alignment voltage control capability e during different operating mode effect, and control ability e comprises e₁、e₂And e₃, e₁Corresponding operating mode 1, e₂Corresponding operating mode 2, e₃Corresponding operating mode 3.Wherein control ability e the maximum centering point voltage controls Ability is the strongest, for adjusting the optimum condition of mid-point voltage.

The present invention comprises the following steps that：

Step 1：Whole 360 degree of vector spaces of diode clamping tri-level inverter are divided according to angle, often 60 degree is a sector, is divided into 6 sectors, and numbering is followed successively by 1～6；60 degree of each sector space is carried out carefully according to angle again Point, front 30 degree of spaces are the 1st cell, and 30 degree of spaces are the 2nd cell afterwards.Whole vector space is divided into 12 cells.According to inverse Becoming device needs output voltage U_oαβIdentification sector and cell number.Concrete grammar：Inverter is needed with output voltage U_oαβIn α axle and Beta -axis component U_αAnd U_βAsk for arc tangent and obtain vector space angle, θ, vector space angle, θ rounds up as sector divided by 60 Number；Remainder is the 1st cell less than 30 degree simultaneously, and remainder is the 2nd cell more than or equal to 30 degree.For example when vector space angle, θ is When 70 degree, round up as 2 divided by 60, sector number is 2, and remainder 10 is less than 30, cell id is 1.

Step 2：Output voltage U is needed according to inverter_oαβPlace sector cell is numbered, and selects to participate in output voltage synthesis Basic space vector, described basic space vector comprises zero vector V₀, transition small vector V_st, middle vector V_mWith big vector V_l. Taking (11st) cell as a example, basic space vector comprises zero vector 111, transition small vector 211, middle vector 210 and big vector 200；

Step 3：Output voltage U is needed according to inverter_oαβPlace sector cell is numbered, and is calculated according to formula (1) and formula (2) Zero vector V₀, transition small vector V_st, middle vector V_m, big vector V_lAction time, be designated as T respectively₀、T_st、T_mAnd T_l；

Step 4：In order to realize mid-point voltage U_neutBalance controls, and needs output voltage U according to inverter_oαβPlace sector Cell number, will be with transition small vector V_stLocus differ 120 degree of two negative small vectors as the first additional small vector V_sa1 Small vector V additional with second_sa2.Wherein, with basis vector in big vector V_lVector V in common synthesis_mAdditional small vector life Entitled first additional small vector V_sa1, with the middle vector V in basis vector_mJointly synthesize 0.5 times of big vector V_lAdditional small vector It is named as the second additional small vector V_sa2.Taking (11st) cell as a example, 121 with big vector 200 can synthesize in vector 210, referred to as First additional small vector V_sa1, 112 can synthesize 0.5 times of big vector 200, the referred to as second additional small vector V with middle vector 210_sa2.

Step 5：Output voltage U is needed according to inverter_oαβPlace sector cell is numbered, with reference to transition small vector V_st, first Additional small vector V_sa1Small vector V additional with second_sa2Corresponding three-phase current I_abcWith mid-point voltage U_neutDeviation, according to formula (6) Calculate control ability e of 3 kinds of operating mode centering point voltages, control ability e comprises e₁、e₂And e₃, e₁Corresponding operating mode 1, e₂Corresponding operating mode 2, e₃Corresponding operating mode 3.Selection control ability e the maximum is optimized operation operating mode.

Step 6：The basic space vector being selected according to step 2, the additional small vector that step 4 selects, step 5 selects Excellent operating condition, each basis vector action time that step 3 calculates, substituting into formula (3), formula (4) or formula (5), to calculate each vector final Action time, generate on off sequence, control corresponding power electronic devices break-make, realize final voltage and control.

It is an advantage of the current invention 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, realizes suppression powder inverter common-mode voltage output on the premise of not increasing device hardware cost, reduces common-mode voltage to other The harm of equipment.

Brief description

Fig. 1 diode clamping tri-level topology；

Fig. 2 three-level inverter space vector divides；

The additional small vector of Fig. 3 (11st) cell and other mutual compositive relation of vector；

Fig. 4 diode clamping tri-level powder inverter common-mode voltage suppression strategy block diagram.

Specific embodiment

Further illustrate the present invention below in conjunction with the drawings and specific embodiments.

Diode clamping tri-level inverter topology is as shown in Figure 1.Inverter gathers positive and negative DC bus-bar voltage, remembers respectively For U_dcPAnd U_dcN；Collection three-phase alternating current, is designated as I_abc, wherein A phase, B phase, C phase corresponding I respectively_a、I_bAnd I_c；To positive direct-current Busbar voltage U_dcPWith negative DC bus-bar voltage U_dcNSummation, obtains DC bus-bar voltage U_dc；Align busbar voltage U_dcPWith negative direct current Busbar voltage U_dcNMake the difference, obtain mid-point voltage deviation delta U_neut.

Inverter adopts vector control method, and in Fig. 1, vector control module output inverter shown in 10 needs output voltage U_oαβ.The present invention is as shown in Figure 4 for diode clamping tri-level powder inverter common-mode voltage suppressing method：

Step 1：By whole vector space, 360 degree are divided according to angle, and every 60 degree is a sector, is divided into 6 Sector, numbering is 1～6 according to this；60 degree of each sector space is finely divided according to angle again, and front 30 degree of spaces are the 1st cell, after 30 degree of spaces are the 2nd cell, and whole vector space is divided into 12 cells, as shown in Figure 2.Output voltage is needed according to inverter U_oαβ, identify sector and cell number, as shown in Fig. 4 110.Concrete grammar：To inverter output voltage U_oαβIn α axle and β axle Component U_αAnd U_βAsk for arc tangent and obtain vector space angle, θ, vector space angle, θ rounds up as sector number divided by 60；With When remainder be the 1st cell less than 30 degree, remainder is the 2nd cell more than or equal to 30 degree.For example when vector space angle, θ is 70 degree When, asking whole upwards is 2, and sector number is 2, and remainder 10 is less than 30, and cell id is 1.

Step 2：According to 110 parts in Fig. 4, output voltage U is needed according to inverter_oαβThe sector cell numbering of identification, choosing Select the basic space vector participating in output voltage synthesis, described basic space vector comprises zero vector V₀, transition small vector V_st、 Middle vector V_mWith big vector V_l, as shown in Fig. 4 120.Taking (11st) cell as a example, basic space vector comprise zero vector 111, Transition small vector 211, middle vector 210 and big vector 200；

Step 3：According to 110 parts in Fig. 4, output voltage U is needed according to inverter_oαβThe sector cell numbering of identification, will DC voltage U_dc, inverter need output voltage U_oαβBring formula (1) (2) into and calculate zero vector V₀, transition small vector V_st, middle arrow Amount V_mWith big vector V_lAction time, it is designated as T respectively₀、T_st、T_mAnd Tl, as shown in Fig. 4 150；

Step 4：In order to realize mid-point voltage U_neutBalance controls, and needs to export according to inverter according to 110 parts in Fig. 4 Voltage U_oαβThe sector cell numbering of identification, selects the first additional small vector V_a1Small vector 2V additional with second_a2, 130 in such as Fig. 4 Shown.Wherein, in synthesizing together with the big vector in basis vector, the additional small vector of vector is named as the first additional small vector V_a1, the additional small vector synthesizing 0.5 times of big vector together with the middle vector in basis vector is named as the second additional small vector V_a2.Taking (11st) cell as a example, 121 with big vector 200 can synthesize in vector 210, the referred to as first additional small vector V_sa1, 112 0.5 times of big vector 200, the referred to as second additional small vector V can be synthesized with middle vector 210_sa2, compositive relation is as shown in Figure 3.

Step 5：According to 110 parts in Fig. 4, output voltage U is needed according to inverter_oαβThe sector cell numbering of identification, ginseng According to transition small vector V_st, the first additional small vector V_a1Small vector V additional with second_a2Corresponding three-phase current I_abcAnd mid-point voltage U_neutDeviation, calculates control ability e of 3 kinds of operating mode centering point voltages according to formula (6), and control ability e comprises e₁、e₂And e₃, e₁Right Answer operating mode 1, e₂Corresponding operating mode 2, e₃Corresponding operating mode 3.Selection control ability e the maximum is optimized operation operating mode, as 140 institute in Fig. 4 Show.

Step 6：The basis vector being selected according to 120 parts in step 2, the additional little arrow that in step 4,130 parts select Amount, the optimized operation operating mode that in step 5,140 parts select, each basis vector action time that in step 3,150 parts calculate, band Enter formula (3), (4) or (5) and calculate each vector final action time, produce on off sequence, control corresponding power electronic devices break-make, Realize the contravarianter voltage output needing, as shown in Fig. 4 160.

Claims (5)

1. a kind of diode clamping tri-level powder inverter common-mode voltage suppressing method it is characterised in that：Described 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, small vector is divided into positive small vector and negative small vector, using without positive small vector PWM (NPSVPWM) Vector modulation strategy, removes positive small vector in the vector of output voltage synthesis, maintains mid-point voltage simultaneously Balance；The negative small vector participating in output voltage synthesis is divided into transition small vector, the first additional little arrow according to Vector modulation relation Amount and the second additional small vector, and when being acted on according to different small vectors, the control ability of centering point voltage derives that optimum operating condition selects Select standard, realize centering point voltage effective control.

2. diode clamping tri-level powder inverter common-mode voltage suppressing method according to claim 1 is it is characterised in that institute The step stating method is as follows：

Step 1, whole 360 degree of vector spaces of diode clamping tri-level inverter is divided according to angle, every 60 degree For a sector, it is divided into 6 sectors, numbering is followed successively by 1～6；60 degree of each sector space is finely divided according to angle again, front 30 degree of spaces are the 1st cell, and 30 degree of spaces are the 2nd cell afterwards；Whole vector space is divided into 12 cells；According to inverter need Want output voltage U_oαβIdentification sector and cell number, specially：Inverter is needed with output voltage U_oαβIn α axle and beta -axis component U_αAnd U_βAsk for arc tangent and obtain vector space angle, θ, vector space angle, θ, divided by 60, rounds up as sector number；Simultaneously Remainder is the 1st cell less than 30 degree, and remainder is the 2nd cell more than or equal to 30 degree；

Step 2, needs output voltage U according to inverter_oαβPlace sector cell is numbered, and selects to participate in the base of output voltage synthesis Plinth space vector, described basic space vector comprises zero vector V₀, transition small vector V_st, middle vector V_mWith big vector V_l；

Step 3, needs output voltage U according to inverter_oαβPlace sector cell is numbered, and calculates zero vector V₀, transition small vector V_st, middle vector V_m, big vector V_lAction time, be designated as T respectively₀、T_st、T_mAnd T_l；

Step 4, in order to realize mid-point voltage U_neutBalance controls, and needs output voltage U according to inverter_oαβPlace sector cell is compiled Number, will be with transition small vector V_stLocus differ 120 degree of two negative small vectors as the first additional small vector V_sa1With second Additional small vector V_sa2；Wherein, with basis vector in big vector V_lVector V in common synthesis_mAdditional small vector be named as One additional small vector V_sa1, with the middle vector V in basis vector_mJointly synthesize 0.5 times of big vector V_lAdditional small vector be named as Second additional small vector V_sa2；

Step 5, needs output voltage U according to inverter_oαβPlace sector cell is numbered, with reference to transition small vector V_st, first add Small vector V_sa1Small vector V additional with second_sa2Corresponding three-phase current I_abcWith mid-point voltage U_neutDeviation, calculates 3 kinds of operating modes pair Control ability e of mid-point voltage, control ability e comprises e₁、e₂And e₃, wherein e₁Corresponding operating mode₁, e₂Corresponding operating mode 2, e₃Corresponding work Condition 3；Selection control ability e the maximum is optimized operation operating mode；

Step 6, the basic space vector being selected according to step 2, the additional small vector that step 4 selects, the optimum fortune that step 5 selects Row operating mode, each basis vector action time that step 3 calculates, substitutes into formula (3), formula (4) or formula (5) and calculates each vector and finally act on Time, generate on off sequence, control corresponding power electronic devices break-make, realize the output of inverter required voltage.

3. diode clamping tri-level powder inverter common-mode voltage suppressing method according to claim 2 is it is characterised in that institute State step 3 and calculate zero vector V₀, transition small vector V_st, middle vector V_m, big vector V_lAction time carry out according to below equation：

During 1 cell of each sector, each vector action time is as shown in formula (1)：

$\left\{\begin{array}{c}{T}_{st}=T_{\min }\\ T_m=\sqrt{2}\cos \frac{\left(2n+1\right)\mathrm{\π}}{6}{U}_{\mathrm{\α}}+\sqrt{2}\sin \frac{\left(2n+1\right)\mathrm{\π}}{6}{U}_{\mathrm{\β}}\\ T_l=-\sqrt{\frac{3}{2}}\cos \frac{\left(n+1\right)\mathrm{\π}}{3}{U}_{\mathrm{\α}}-\sqrt{\frac{3}{2}}\sin \frac{\left(n+1\right)\mathrm{\π}}{3}{U}_{\mathrm{\β}}-\frac{T_{\min }}{2}\\ T_0=-\sqrt{\frac{1}{2}}\cos \frac{\left(2n-1\right)\mathrm{\π}}{6}{U}_{\mathrm{\α}}-\sqrt{\frac{1}{2}}\sin \frac{\left(2n-1\right)\mathrm{\π}}{6}{U}_{\mathrm{\β}}-\frac{T_{\min }}{2}+1\end{array}\right.---\left(1\right)$

During 2 cell of each sector, each vector action time is as shown in formula (2)：

$\left\{\begin{array}{c}{T}_{st}=T_{\min }\\ T_m=\sqrt{2}\cos \frac{\left(2n-3\right)\mathrm{\π}}{6}{U}_{\mathrm{\α}}+\sqrt{2}\sin \frac{\left(2n-3\right)\mathrm{\π}}{6}{U}_{\mathrm{\β}}\\ T_l=\sqrt{\frac{3}{2}}\cos \frac{\left(n+1\right)\mathrm{\π}}{3}{U}_{\mathrm{\α}}+\sqrt{\frac{3}{2}}\sin \frac{\left(n+1\right)\mathrm{\π}}{3}{U}_{\mathrm{\β}}-\frac{T_{\min }}{2}\\ T_0=-\sqrt{\frac{1}{2}}\cos \frac{\left(2n-1\right)\mathrm{\π}}{6}{U}_{\mathrm{\α}}-\sqrt{\frac{1}{2}}\sin \frac{\left(2n-1\right)\mathrm{\π}}{6}{U}_{\mathrm{\β}}-\frac{T_{\min }}{2}+1\end{array}\right.---\left(2\right)$

In formula, T₀For zero vector V₀Action time, T_stFor transition small vector V_stAction time, T_mFor middle vector V_mEffect Time, T_lFor big vector V_lAction time, n be sector number, T_minFor the least action time of transition small vector distribution, V_αAnd V_β Being respectively inverter needs output voltage U_0αβComponent in α axle and β axle.

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 control ability e of three kinds of operating mode centering point voltages, and control ability e comprises e₁、e₂And e₃, wherein e₁Corresponding work Condition 1, e₂Corresponding operating mode 2, e₃Corresponding operating mode 3；The method selecting control ability e the maximum to be optimized operation operating mode is as follows；

According to transition small vector V_st, the first additional small vector V_sa1Small vector V additional with second_sa2Effect corresponding midpoint current symbol With mid-point voltage adjustment direction, the control of centering point voltage is divided into 3 kinds of operating modes；

Operating mode 1：Transition small vector effect corresponding midpoint current symbol meets mid-point voltage and controls requirement, and adjustment transition small vector is made Use time control mid-point voltage；

Operating mode 2：First additional small vector effect corresponding current symbol meets mid-point voltage and controls requirement, increases by first and adds little arrow Amount participates in output voltage synthesis；

Operating mode 3：Second additional small vector effect corresponding current symbol meets mid-point voltage and controls requirement, increases by second and adds little arrow Amount participates in output voltage synthesis；

When acting in conjunction with different operating modes, the adjustment characteristic of centering point voltage and zero vector time take relation, the different operating mode pair of definition The control ability of mid-point voltage is e, as shown in formula (6)：

$\left\{\begin{array}{c}{e}_1=2\left(-i_a\right)*sign\left({\mathrm{\ΔU}}_{neut}\right)\\ e_2=\left(-i_b-i_b\right)*sign\left({\mathrm{\ΔU}}_{neut}\right)\\ e_3=\left(-i_c+i_b\right)*sign\left({\mathrm{\ΔU}}_{neut}\right)\end{array}\right.---\left(6\right)$

In formula (6), e₁、e₂、e₃It is respectively operating mode 1, operating mode 2, the control ability of operating mode 3 centering point voltage, wherein operating mode 1 centering Control ability e of point voltage₁2 multiplying factors are taken to be because that operating mode 1 is operating mode 2 or operating mode 3 to zero vector holding timeOperating mode 2 Control ability e of centering point voltage₂Two electric current i of middle appearance_bIt is because during operating mode 2 increasing by the first additional small vector effect and subtract Little middle vector effect all corresponds to B phase current, sign (Δ U_neut) it is mid-point voltage symbol；The implication of formula (6) is according to midpoint electricity Pressure symbol and vector action characteristic obtain alignment voltage control capability e, wherein e during different operating mode effect₁Corresponding operating mode 1, e₂Right Answer operating mode 2, e₃Corresponding operating mode 3；Control ability e the maximum alignment voltage control capability is the strongest, for controlling mid-point voltage Good operating mode.

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 basic space vector being selected according to step 2, the additional small vector that step 4 selects, the optimized operation work that step 5 selects Condition, each basis vector action time that step 3 calculates, substitutes 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)：

$\left\{\begin{array}{c}{T_{sa}}^{,}=0\\ {T_0}^{,}=T_0-\frac{1}{2}K\left(T_0-T_{\min }\right)\\ {T_{st}}^{,}=T_{st}+K\left(T_0-T_{\min }\right)\\ {T_m}^{,}=T_m\\ {T_l}^{,}=T_l-\frac{1}{2}K\left(T_0-T_{\min }\right)\end{array}\right.---\left(3\right)$

When controlling mid-point voltage using the first additional small vector, each vector final action time is as shown in formula (4)：

$\left\{\begin{array}{c}{T_{sa}}^{,}=K\left(T_0-T_{\min }\right)\\ {T_0}^{,}=T_0-K\left(T_0-T_{\min }\right)\\ {T_{st}}^{,}=T_{st}\\ {T_m}^{,}=T_m-K\left(T_0-T_{\min }\right)\\ {T_l}^{,}=T_l+K\left(T_0-T_{\min }\right)\end{array}\right.---\left(4\right)$

When controlling mid-point voltage using the second additional small vector, each vector final action time is as shown in formula (5)：

$\left\{\begin{array}{c}{T_{sa}}^{,}=\frac{2}{3}K\left(T_0-T_{\min }\right)\\ {T_0}^{,}=T_0-K\left(T_0-T_{\min }\right)\\ {T_{st}}^{,}=T_{st}\\ {T_m}^{,}=T_m+\frac{2}{3}K\left(T_0-T_{\min }\right)\\ {T_l}^{,}=T_s-\frac{1}{3}K\left(T_0-T_{\min }\right)\end{array}\right.---\left(5\right)$

In formula (3), formula (4), formula (5), T_sa’、T₀’、T_st’、T_m’、T_l' be respectively consider additional little after neutral-point voltage balance Vector V_sa, zero vector V₀, transition small vector V_st, middle vector V_m, greatly swear V_lMeasure add during final action time, wherein operating mode 2 little Vector V_saCorresponding first additional small vector V_sa1, additional small vector V during operating mode 3_saCorresponding second additional small vector V_sa2；T₀、T_st、 T_m、T_lIt is respectively before adopting mid-point voltage to control by formula (1) or the calculated zero vector V of formula (2)₀, transition small vector V_st, in Vector V_m, big vector V_lAction time, T_minThe least action time distributed for transition small vector, K is according to mid-point voltage deviation PI closed loop adjusts output.