CN202076951U - Integrated control system of modular multi-lever converter - Google Patents

Abstract

The utility model relates to an integrated control system of a modular multi-lever converter, which comprises M phases of modular multi-lever converters, wherein each phase of modular multi-lever converter is connected with a respective integrated control device, all the integrated control devices are connected with M phases of pulse-width modulation (PWM) signal generators, have same structures and respectively comprise an upper bridge arm controller, a master controller and a lower bridge arm controller, an output terminal of each phase of modular multi-lever converter is respectively connected with input terminals of the upper bridge arm controller, the master controller and the lower bridge arm controller, the output terminal of the master controller respectively outputs PWM common duty ratio dap of an upper bridge arm to the upper bridge arm controller and PWM common duty ratio dan of a lower bridge arm to the lower bridge arm controller, and the output terminals of the upper bridge arm controller and the lower bridge arm controller are connected with the PWM signal generators with corresponding phases. The integrated control system is applicable to various PWM modes, can flexibly control circulation to meet special needs, and is clear and definite in physical significance, and sufficient in theoretical basis.

Description

A kind of complex control system of modular multilevel converter

Technical field

The utility model relates to a kind of complex control system of modular multilevel converter, belongs to the control technology field of multilevel power electronic power converter.

Background technology

The modular multilevel converter topology adopts tandem type, modular, need not the stepped-up voltage that the direct series connection of power device just can obtain many level, have lower dU/dt and lower voltage harmonic content, in/have broad application prospects in the high-voltage large-capacity system.This converter topology structure as shown in Figure 1, among the figure, last brachium pontis and following brachium pontis respectively have the individual sub-module cascade of N to form, each submodule is a half-bridge structure, the submodule DC side parallel has identical capacitor.Because each submodule dc bus capacitor of modular multilevel converter is in suspended state, difference can appear discharging and recharging in each submodule electric capacity during operation, therefore can cause the imbalance problem of capacitance voltage.The safe operation of the uneven directly threat of capacitance voltage converter, thus this problem can effectively solve be the key of modular multilevel converter safety, reliability service.

" based on the dc-voltage balance control of the 50MVA STATCOM of chain inverter " literary composition (author Liu Wenhua etc.) in the publication of " Proceedings of the CSEE " 2004 the 24th volume the 4th phase 145-150 page or leaf is studied the DC side submodule capacitive balance control method of tandem type STATCOM, proposed to adopt to add the special power circuit, realized the capacitance voltage Balance Control by discharging and recharging of control dc bus capacitor device in each submodule DC side.But this method need additionally increase the special power circuit of external complex, cost height, big, the control complexity of volume.

At " novel many level VSC submodule capacitance parameter with all press strategy " literary composition (author's fourth champion etc.) of " Proceedings of the CSEE " 2009 the 29th volume the 30th phase 1-6 page or leaf publication the method that the capacitance voltage Balance Control is carried out in based on software ordering has been proposed, this method adopts the size to each submodule dc capacitor voltage to compare, sort, according to brachium pontis power (or electric current) direction, determine the switching state of each submodule again.When the brachium pontis absorbed power, drop into the minimum submodule of voltage; Otherwise, when brachium pontis sends power, drop into the highest submodule of voltage.(Pulse-Width Modulation, PWM) mode has specific (special) requirements to this method, is not suitable for the phase-shifting carrier wave formula PWM mode that is generally adopted in multi-level converter to pulse-width modulation.

Publication number is in the Chinese patent of CN1767345A disclosed " a kind of hybrid clamped multilevel inverter top ", a kind of many level topology that realizes clamp by active device and passive device has jointly been proposed, can not need adjunct circuit to realize the midpoint potential balance, solve traditional many level topology and counted the problem that the capacitance voltage balance under the situation is difficult to realize at high level.Belong to many level of clamp type topological structure of the direct cascaded structure of power device but publication number is the Chinese patent of CN1767345A disclosed " a kind of hybrid clamped multilevel inverter top ", do not belong to same type multi-level converter topology with modular multilevel topology shown in Figure 1, there is essential distinction in two kinds of topological structures, therefore, the capacitance voltage balancing technique of this clamping multilevel converter topology is not suitable for modular multilevel topology shown in Figure 1, does not solve the equilibrium problem of each submodule capacitance voltage of modular multilevel converter.

Publication number is in the Chinese patent of CN101546964A disclosed " module combined multi-level converter ", disclose a kind of combined multi-level converter topology, proposed to realize a kind of converter topology that can be used for the mesohigh large-power occasions by the connection in series-parallel of using power cell.But publication number is the Chinese patent of CN101546964A, and disclosed " module combined multi-level converter " only is to disclose a kind of combined multi-level converter topology, do not solve the equilibrium problem of each submodule capacitance voltage of modular multilevel converter.

The utility model content

The purpose of this utility model proposes a kind of complex control system of modular multilevel converter exactly for addressing the above problem, with the equilibrium problem and the control problem of each submodule capacitance voltage of solving this converter.This method is from the angle of power-balance, and its basic thought is by regulating total active power of this converter, to realize the Balance Control of the upper and lower brachium pontis total capacitance voltage of this converter; Distribute by the active power of regulating between the upper and lower brachium pontis, realize the capacitance voltage Balance Control between the upper and lower brachium pontis; By finely tuning the distribution of the active power between each submodule on the same brachium pontis, realize the capacitance voltage Balance Control between each submodule on the same brachium pontis.This method has not only realized each submodule capacitance voltage Balance Control, and electric current, the voltage control of converter have been realized, it is a kind of integrated control method of modular multilevel converter, explicit physical meaning, do not need to use the capacitor special use to discharge and recharge power circuit, be applicable to various PWM modes.

For achieving the above object, the utility model adopts following technical scheme:

A kind of integrated control method of modular multilevel converter, by each submodule capacitance voltage of the upper and lower brachium pontis of detection module multi-level converter, upper and lower brachium pontis electric current, and AC side supply voltage are through obtaining the public duty ratio of upper and lower brachium pontis PWM after the master controller calculation process; The public duty ratio of each submodule capacitance voltage of upper and lower brachium pontis and above-mentioned upper and lower brachium pontis PWM obtains the PWM duty ratio of upper and lower each submodule of brachium pontis through upper and lower brachium pontis controller calculation process; The PWM duty ratio process pwm signal generator of each submodule produces the pwm control signal of each submodule, realizes electric current, the voltage control of each submodule capacitance voltage Balance Control and converter.

Its concrete steps are:

(1), obtains brachium pontis N sub-module capacitance voltage detecting value u by each N of brachium pontis on the detection module multi-level converter sub-module capacitance voltage _Ap1, u _Ap2... and u _ApN,, obtain brachium pontis submodule average capacitor voltage by the unit A that averages

By each N of brachium pontis under the detection module multi-level converter sub-module capacitance voltage, obtain down brachium pontis N sub-module capacitance voltage detecting value u _An1, u _An2... and u _AnN,, obtain down brachium pontis submodule average capacitor voltage by the unit B of averaging

With the above-mentioned brachium pontis submodule average capacitor voltage of going up

With following brachium pontis submodule average capacitor voltage

Be sent to the unit C that averages, obtain upper and lower brachium pontis overall average capacitance voltage

(2) by detecting AC side supply voltage u _Sa, handle through normalization unit A, obtain corresponding unit amplitude supply voltage u _Sau

(3) with the overall average capacitance voltage

With Voltage Reference u _Dc ^*Be sent to the total capacitance voltage controller and handle, obtain total capacitance voltage control current i ₀ ^*

(4) will go up brachium pontis submodule and following brachium pontis submodule average capacitor voltage

With Be sent to/following bridge arm balance controller handles the output valve I that obtains _ACMWith unit amplitude supply voltage u _SauAfter multiplying each other, multiplier l obtains/following bridge arm balance adjustment electric current Δ i _AC, i.e. Δ i _AC=I _ACMU _Sau

(5) with AC side power supply reference current i _Sa ^*, i ₀ ^*, Δ i _ACElectric current with the generation of circulation unit

Send into arithmetic element A and obtain the brachium pontis reference current Promptly $i_{\mathrm{ap}}^{*}=\frac{1}{2}({i_{\mathrm{sa}}}^{*}+\mathrm{\Δ}{i}_{\mathrm{AC}})+{i_0}^{*}+i_{\mathrm{aL}}^{*};$

(6) with AC side power supply reference current i _Sa ^*, i ₀ ^*, Δ i _ACElectric current with the generation of circulation unit

Send into arithmetic element B and obtain down the brachium pontis reference current Promptly $i_{\mathrm{an}}^{*}=\frac{1}{2}({i_{\mathrm{sa}}}^{*}-\mathrm{\Δ}{i}_{\mathrm{AC}})-{i_0}^{*}-i_{\mathrm{aL}}^{*};$

(7) will go up brachium pontis current detection value i _ApWith reference current

Be sent to current controller AP and handle, obtain the public duty ratio d of brachium pontis PWM _Ap

(8) will descend brachium pontis current detection value i _AnWith reference current

Be sent to current controller AB and handle, obtain down the public duty ratio d of brachium pontis PWM _An

(9) will go up brachium pontis current detection value i _ApSend into the normalization unit AP and handle, obtain brachium pontis unit amplitude current i _ApuTo descend brachium pontis current detection value i _AnSend into normalization unit AN and handle, obtain down brachium pontis unit amplitude current i _Anu

(10) will

With last brachium pontis j sub-module capacitance voltage detecting value u _Apj, wherein, j=1,2 ..., N-1 is sent to j submodule fine setting of brachium pontis controller APj and handles the output D of fine setting controller APj _MpjThrough corresponding multiplier APj and i _ApuPass through corresponding adder APj and the public duty ratio d of last brachium pontis PWM after multiplying each other again _ApAddition obtains j submodule PWM of brachium pontis duty ratio d _Apj

(11) N-1 is gone up brachium pontis fine setting controller AP1, fine setting controller AP2 ... and the output D of fine setting controller AP (N-1) _Mp1, D _Mp2... and D _MpN-1Sue for peace after opposite sign device AP oppositely obtains D through adder AP _MpN, again with i _ApuAPN multiplies each other through multiplier, then with the public duty ratio d of last brachium pontis PWM _ApAddition obtains N submodule PWM of brachium pontis duty ratio d _ApN

(12) will

With following brachium pontis j sub-module capacitance voltage detecting value u _Anj, j=1 wherein, 2 ..., N-1 is sent to down j submodule fine setting of brachium pontis controller ANj and handles the output D of fine setting controller ANj _MnjThrough corresponding multiplier ANj and i _AnuPass through corresponding adder ANj and the public duty ratio d of following brachium pontis PWM after multiplying each other again _AnAddition obtains down j submodule PWM of brachium pontis duty ratio d _Anj

(13) with N-1 down brachium pontis fine setting controller AN1, fine setting controller AN2 ... and the output D of fine setting controller AN (N-1) _Mn1, D _Mn2... and D _MnN-1Sue for peace after opposite sign device AN oppositely obtains D through adder AN _MnN, again with i _AnuANN multiplies each other through multiplier, then with the public duty ratio d of following brachium pontis PWM _AnAddition obtains down N submodule PWM of brachium pontis duty ratio d _AnN

(14) with each submodule PWM duty ratio d _Ap1, d _Ap2... and d _ApNAnd d _An1, d _An2... and d _AnNBe sent to the PWM generator unit, produce the pwm control signal of each submodule.

In the described step (2), by detecting AC side supply voltage u _Sa, adopt known Phase Lock Technique, obtain and u _SaWith the unit amplitude SIN function of frequency homophase, replace unit amplitude supply voltage u _Sau

In the described step (9), use the brachium pontis reference current

Brachium pontis current detection value i in the replacement _Ap, use brachium pontis reference current down Replace brachium pontis current detection value i down _AnThat is, will go up the brachium pontis reference current Send into the normalization unit AP and handle, obtain brachium pontis unit amplitude current i _ApuTo descend the brachium pontis reference current

Send into normalization unit AN and handle, obtain down brachium pontis unit amplitude current i _Anu

In described step (5) and (6), the electric current that the circulation unit produces

Satisfy

With

Wherein, T represents the AC side supply voltage cycle,

Amplitude by AC side power supply reference current i _Sa ^*The size decision.

In described step (5) and (6), when modular multilevel converter dc bus external load rather than DC power supply, need to increase the DC bus-bar voltage closed loop controller, the output control AC side power supply reference current i of this controller _Sa ^*The real component amplitude, the input of this controller is from DC bus-bar voltage detected value and DC bus-bar voltage reference value.

A kind of complex control system of modular multilevel converter, it comprises M phase module multi-level converter, each phase module multi-level converter is connected with separately composite control apparatus, each composite control apparatus then with M mutually the pwm signal generator connect; Wherein, described each composite control apparatus structure is identical, comprises brachium pontis controller, master controller and following brachium pontis controller; The modular multilevel converter output terminal of each phase is connected with last brachium pontis controller, master controller and following brachium pontis controller input respectively; The output of master controller is exported the public duty ratio d of brachium pontis PWM respectively _ApTo last brachium pontis controller, output is the public duty ratio d of brachium pontis PWM down _AnArrive brachium pontis controller down; Last brachium pontis controller is connected with corresponding pwm signal generator mutually with following brachium pontis controller output end.

Described master controller comprises the unit A that averages, the unit B of averaging, their input is connected with the modular multilevel converter output terminal, output then is connected with last/following bridge arm balance controller with the unit C that averages respectively, the output of unit C of averaging is connected with the total capacitance voltage controller, on/following bridge arm balance controller output end is connected with multiplier I, and multiplier I also is connected with normalization unit AN; The total capacitance voltage controller is connected with arithmetic element A, arithmetic element B respectively with multiplier I, and the circulation unit also is connected with arithmetic element A, arithmetic element B simultaneously; Arithmetic element A, arithmetic element B connect with corresponding current controller AN, current controller AP respectively; Submodule dc bus capacitor reference voltage is sent into total capacitance voltage controller input; The phase supply voltage of modular multilevel converter is sent into normalization unit AN; Following brachium pontis phase current is sent into current controller AN.

It is described that upward the brachium pontis controller is identical with following brachium pontis controller architecture, wherein:

The described brachium pontis controller of going up comprises with each and goes up the individual sub-module capacitance voltage detecting value u of brachium pontis N _Ap1, u _Apj... and u _ApNCorresponding fine setting controller AP1, fine setting controller APj ... fine setting controller AP (N-1); Each finely tune controller AP output respectively with corresponding multiplier AP1, multiplier APj ... multiplier AP (N-1) connects; Simultaneously respectively finely tuning controller AP output also is connected with adder AP, adder AP is connected with opposite sign device AP, multiplier APN successively, the output of each multiplier AP and corresponding adder AP1 ... adder APj ... adder AP (N-1) ... adder APN connects; Last brachium pontis current detection value i _ApSend into the normalization unit AP, normalization unit AP and each multiplier AP1 ... multiplier APN connects;

Described brachium pontis controller down comprises and each time brachium pontis N sub-module capacitance voltage detecting value u _An1, u _Anj... and u _AnNCorresponding fine setting controller AN1, fine setting controller ANj ... fine setting controller AN (N-1); Each finely tune controller AN output respectively with corresponding multiplier AN1, multiplier ANj ... multiplier AN (N-1) connects; Simultaneously respectively finely tuning controller AN output also is connected with adder AN, adder AN is connected with opposite sign device AN, multiplier ANN successively, the output of each multiplier AN and corresponding adder AN1 ... adder ANj ... adder AN (N-1) ... adder ANN connects; Following brachium pontis current detection value i _AnSend into normalization unit AN, normalization unit AN and each multiplier AN1 ... multiplier ANN connects.

Theoretical foundation of the present utility model is:

By uniphase mode blocking multi-level converter shown in Figure 2 as can be known, establishing the AC side supply voltage is u _Sa, the AC side source current is i _Sa, each submodule output total voltage switch periods mean value of upper and lower brachium pontis is respectively u _Ap, u _An, the electric current of upper and lower brachium pontis is respectively i _Ap, i _An, AC side power supply power absorbed is P _AC, the active power that dc bus sends is P _DC, total active power that each submodule of upper and lower brachium pontis absorbs is respectively P _Ap, P _An, establishing the AC side power cycle is T.

During stable state, if ignore the influence of supposing inductance L, then voltage relationship is:

$\left\{\begin{array}{c}{u}_{\mathrm{ap}}\&ap;\frac{U_d}{2}-u_{\mathrm{sa}}\\ u_{\mathrm{an}}\&ap;\frac{{\mathrm{<figure-callout\; id="2"\; label="U\; d"\; filenames="DEST\_PATH\_HDA0000069054230000041.png"\; state="\{\{state\}\}">U</figure-callout>}}_d}{2}+u_{\mathrm{sa}}\end{array}\right.---\left(1\right)$

Current relationship is:

i _sa＝i _ap+i _an (2)

With current i _ApAnd i _AnDo following decomposition

$\left\{\begin{array}{c}{i}_{\mathrm{ap}}=i_{\mathrm{apAC}}+i_0\\ i_{\mathrm{an}}=i_{\mathrm{anAC}}-i_0\end{array}\right.---\left(3\right)$

Wherein, i _ApAC, i _AnACAnd i ₀Satisfy following formula,

$\left\{\begin{array}{c}{\&Integral;}_0^T{U}_d{i}_{\mathrm{apAC}}\mathrm{dt}=0\\ {\&Integral;}_0^T{U}_d{i}_{\mathrm{apnAC}}\mathrm{dt}=0\\ {\&Integral;}_0^T{u}_{\mathrm{sa}}{i}_0\mathrm{dt}=0\end{array}\right.---\left(4\right)$

Concern by the law of conservation of energy available power:

P _DC＝P _AC+P _ap+P _an (5)

Wherein

$\left\{\begin{array}{c}{P}_{\mathrm{AC}}=-\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{sa}}{i}_{\mathrm{sa}}\mathrm{dt}=-\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{sa}}(i_{\mathrm{apAC}}+i_{\mathrm{anAC}})\mathrm{dt}\\ P_{\mathrm{DC}}=-\frac{1}{T}{\&Integral;}_0^T\frac{U_d}{2}{i}_{\mathrm{ap}}\mathrm{dt}+\frac{1}{T}{\&Integral;}_0^T\frac{U_d}{2}{i}_{\mathrm{an}}\mathrm{dt}=-\frac{1}{T}{\&Integral;}_0^T{U}_d{i}_0\mathrm{dt}\end{array}\right.---\left(6\right)$

$\left\{\begin{array}{c}{P}_{\mathrm{ap}}=-\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{ap}}{i}_{\mathrm{ap}}\mathrm{dt}=-\frac{1}{T}{\&Integral;}_0^T\frac{U_d}{2}{i}_0\mathrm{dt}+\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{sa}}{i}_{\mathrm{apAC}}\mathrm{dt}\\ P_{\mathrm{an}}=\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{an}}{i}_{\mathrm{an}}\mathrm{dt}=-\frac{1}{T}{\&Integral;}_0^T\frac{U_d}{2}{i}_0\mathrm{dt}+\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{sa}}{i}_{\mathrm{anAC}}\mathrm{dt}\end{array}\right.---\left(7\right)$

By formula (6) as can be seen, by adjusting current i ₀In flip-flop, can adjust the active power P that dc bus sends _DC, and then regulate the active power summation (P that upper and lower brachium pontis submodule absorbs _Ap+ P _An), thereby adjust full-bridge each submodule total capacitance voltage of arm or mean value size.

By formula (7) as can be seen, by adjusting current i _ApACOr i _AnACIn the active current composition (promptly with supply voltage u _SaWith frequently, homophase or with the electric current composition of shape), i.e. the active power P that absorbs of the upper and lower brachium pontis submodule of scalable _ApAnd P _AnBetween distribution, thereby adjust the equilibrium of each the submodule total capacitance voltage between the upper and lower brachium pontis.Can get P by formula (7) _ApAnd P _AnDifference be

$P_{\mathrm{ap}}-P_{\mathrm{an}}=\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{sa}}(i_{\mathrm{apAC}}-i_{\mathrm{apAC}})\mathrm{dt}=\frac{1}{T}{\&Integral;}_0^T{u}_{\mathrm{sa}}\mathrm{\&Delta;}{i}_{\mathrm{AC}}\mathrm{dt}---\left(8\right)$

Δ i in the formula _ACFor with supply voltage u _SaWith frequently, homophase or with the electric current composition of shape, have

Δi _AC＝i _apAC-i _anAC (9)

Convolution (2) and (3) can be arrived

$\left\{\begin{array}{c}{i}_{\mathrm{apAC}}=\frac{1}{2}(i_{\mathrm{sa}}+\mathrm{\&Delta;}{i}_{\mathrm{AC}})\\ i_{\mathrm{anAC}}=\frac{1}{2}(i_{\mathrm{sa}}-\mathrm{\&Delta;}{i}_{\mathrm{AC}})\end{array}\right.---\left(10\right)$

Owing to can have each species diversity between each submodule in the reality, the capacitance voltage equilibrium problem between each submodule on the same brachium pontis also can appear, and can adopt the method for each submodule active power of fine setting to realize its capacitance voltage Balance Control for this reason.

In order to reach the poor of total active power that the upper and lower brachium pontis submodule of above-mentioned adjusting absorbs, active power that upper and lower brachium pontis submodule absorbs, and the purpose of the active power of each submodule, the utility model adopts many closed-loop controls of difference FEEDBACK CONTROL and each submodule capacitance voltage FEEDBACK CONTROL of the direct FEEDBACK CONTROL of upper and lower brachium pontis electric current, total capacitance average voltage FEEDBACK CONTROL, upper and lower brachium pontis total capacitance mean value.Concrete scheme is:

1) the direct FEEDBACK CONTROL of upper and lower brachium pontis electric current realizes the quick control of upper and lower brachium pontis electric current by current controller, and the output of its controller produces the public duty ratio d of upper and lower brachium pontis PWM respectively _ApAnd d _An, it is input as by arithmetic element and calculates the upper and lower brachium pontis reference current i that produces _Ap ^*And i _An ^*, and detect current i _ApAnd i _An

2) total capacitance average voltage FEEDBACK CONTROL realizes the closed-loop control of each submodule total capacitance average voltage by the total capacitance voltage controller, and its controller is output as current i ₀In the direct current composition

Have

$i_0=i_0^{*}+i_{\mathrm{aL}}^{*}---\left(11\right)$

In the formula

Represent non-direct current and satisfy the electric current (can be 0) of formula (4), be called circulation here, promptly

Satisfy following relationship.

$\left\{\begin{array}{c}{\&Integral;}_0^T{U}_d{i}_{\mathrm{aL}}^{*}\mathrm{dt}=0\\ {\&Integral;}_0^T{u}_{\mathrm{sa}}{i}_{\mathrm{aL}}^{*}\mathrm{dt}=0\end{array}\right.---\left(12\right)$

3) the difference FEEDBACK CONTROL of upper and lower brachium pontis total capacitance mean value realizes equilibrium control between the upper and lower brachium pontis total capacitance average voltage by last/following bridge arm balance controller, and its controller is output as electric current Δ i _ACAmplitude I _ACM, have

Δi _AC＝I _ACM·u _sau (13)

In the formula, u _SauThe supply voltage u of representation unit amplitude _Sa, can be by u _SaObtain through normalization, also can be and u _SaUnit amplitude SIN function with the frequency homophase.

4) establish i _Sa ^*Be current i _SaReference signal, can get the reference current i of upper and lower brachium pontis current controller in sum _Ap ^*And i _An ^*For

$\left\{\begin{array}{c}{i_{\mathrm{ap}}}^{*}=\frac{1}{2}({i_{\mathrm{sa}}}^{*}+\mathrm{\&Delta;}{i}_{\mathrm{AC}})+{i_0}^{*}+{i_{\mathrm{aL}}}^{*}\\ {i_{\mathrm{an}}}^{*}=\frac{1}{2}({i_{\mathrm{sa}}}^{*}-\mathrm{\&Delta;}{i}_{\mathrm{AC}})-{i_0}^{*}-{i_{\mathrm{aL}}}^{*}\end{array}\right.---\left(14\right)$

5) each submodule capacitance voltage FEEDBACK CONTROL can realize capacitance voltage Balance Control between each submodule of same brachium pontis by submodule capacitance voltage fine setting controller, and j fine setting controller is output as submodule PWM duty ratio amount trimmed Δ d _Apj(or Δ d _Anj) amplitude D _Mpj(or D _Mnj), the i of unit amplitude _Ap(or i _Ap ^*) and i _An(or i _An ^*) use i respectively _ApuAnd i _AnuExpression, the two is through i _Ap(or i _Ap ^*) and i _An(or i _An ^*) normalization obtain j submodule PWM duty ratio amount trimmed Δ d then _Apj(or Δ d _Anj) be

$\left\{\begin{array}{c}\mathrm{\&Delta;}{d}_{\mathrm{apj}}=D_{\mathrm{mpj}}\&CenterDot;i_{\mathrm{apu}}\\ \mathrm{\&Delta;}{d}_{\mathrm{anj}}=D_{\mathrm{mnj}}\&CenterDot;i_{\mathrm{anu}}\end{array}\right.,j=\mathrm{1,2},...,N---\left(15\right)$

Amount trimmed Δ d _ApjWith Δ d _AnjRespectively with the public duty ratio d of upper and lower brachium pontis PWM _ApAnd d _AnAfter the stack, can obtain the public duty ratio d of PWM of j submodule _ApjAnd d _Anj, promptly

$\left\{\begin{array}{c}{d}_{\mathrm{apj}}=d_{\mathrm{ap}}+\mathrm{\&Delta;}{d}_{\mathrm{apj}}\\ d_{\mathrm{anj}}=d_{\mathrm{an}}+\mathrm{\&Delta;}{d}_{\mathrm{anj}}\end{array}\right.,j=\mathrm{1,2},...,N---\left(16\right)$

Produce pwm control signal through the pwm signal generator again.

Capacitance voltage between each submodule of same brachium pontis fine setting control its objective is the power division between each submodule of fine setting, and this just requires the brachium pontis current amplitude can not be too small.Suitable adding circulation

The too small problem of brachium pontis current amplitude in the time of can solving converter and be in zero load or underloading.Can be according to i _Sa ^*Size decide adding circulation Size.

6) when modular multilevel converter dc bus external load rather than DC power supply, need to increase the DC bus-bar voltage closed loop controller, the output control AC side power supply reference current i of this controller _Sa ^*The amplitude of real component.

The integrated control method of above-mentioned a kind of modular multilevel converter of the present utility model not only can be realized the Balance Control of each submodule capacitance voltage, and can realize electric current, the voltage control of converter.

The beneficial effects of the utility model are:

1) do not need extra capacitor charging/discharging special circuit;

2) be applicable to various PWM modes;

3) when realizing each the module capacitance balance of voltage control of modular multilevel converter, also realized electric current, the voltage control of converter, be a kind of integrated control method of modular multilevel converter;

4) can control circulation flexibly, satisfy special requirement;

5) explicit physical meaning, theoretical foundation is abundant.

Description of drawings

Fig. 1 is typical modular multilevel converter three-phase topological structure schematic diagram.

Fig. 1 a is submodule among Fig. 1.

Fig. 1 b is the concrete structure figure of Fig. 1 a.

Fig. 2 is single-phase topological structure of modular multilevel converter and master control schematic diagram of the present utility model.

Fig. 3 is the control principle figure of master controller among the control principle figure of the present utility model.

Fig. 4 is the control principle figure that goes up the brachium pontis controller among the control principle figure of the present utility model.

Fig. 5 is the control principle figure of following brachium pontis controller among the control principle figure of the present utility model.

Fig. 6 is the control system schematic diagram that the utility model is applied to heterogeneous modular multilevel converter.

Wherein, 1, master controller, 2, last brachium pontis controller, 3, following brachium pontis controller, 4, the modular multilevel converter, 5, the pwm signal generator, 6, the complex control system unit, 7, M phase pwm signal generator, 8, M phase module multi-level converter, 9, complex control system unit 1,10, complex control system unit k, 11, complex control system unit M, 1-1, the unit A that averages, 1-2, the unit B of averaging, 1-3, unit C averages, 1-4, on/following bridge arm balance controller, 1-5, normalization unit AN, 1-6, the total capacitance voltage controller, 1-7, multiplier I, 1-8, arithmetic element A, 1-9, arithmetic element B, 1-10, current controller AN, 1-11, current controller AP, 1-12, the circulation unit, 2-1, fine setting controller AP1,2-2, fine setting controller APj, 2-3, fine setting controller AP (N-1), 2-4, the normalization unit AP, 2-5, multiplier AP1,2-6, multiplier APj, 2-7, multiplier AP (N-1), 2-8, adder AP1,2-9, adder APj, 2-10, adder AP (N-1), 2-11, adder AP, 2-12, opposite sign device AP, 2-13, multiplier APN, 2-14, adder APN, 3-1, fine setting controller AN1,3-2, fine setting controller ANj, 3-3, fine setting controller AN (N-1), 3-4, normalization unit AN, 3-5, multiplier AN1,3-6, multiplier ANj, 3-7, multiplier AN (N-1), 3-8, adder AN1,3-9, adder ANj, 3-10, adder AN (N-1), 3-11, adder AN, 3-12, opposite sign device AN, 3-13, multiplier ANN, 3-14, adder ANN, 4-1, the positive direct-current bus, 4-2, negative dc bus.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

Fig. 1 has provided typical modular multilevel converter three-phase topological structure schematic diagram.Whenever go up mutually/following brachium pontis has N submodule to constitute, and the structure of each submodule is shown in Fig. 1 a, Fig. 1 b.

Among Fig. 2-6, a kind of complex control system of modular multilevel converter, it comprises M phase module multi-level converter 8, and each phase module multi-level converter 4 is connected with separately composite control apparatus, each composite control apparatus then with M mutually pwm signal generator 7 connect; Wherein, described each composite control apparatus structure is identical, comprises brachium pontis controller 2, master controller 1 and following brachium pontis controller 3; Modular multilevel converter 4 outputs of each phase are connected with last brachium pontis controller 2, master controller 1 and following brachium pontis controller 3 inputs respectively; The output of master controller 1 is exported the public duty ratio d of brachium pontis PWM respectively _ApTo last brachium pontis controller 2, output is the public duty ratio d of brachium pontis PWM down _AnArrive brachium pontis controller 3 down; Last brachium pontis controller 2 is connected with corresponding pwm signal generator 5 mutually with following brachium pontis controller 3 outputs.The last brachium pontis of modular multilevel converter 4 is connected with negative dc bus 4-2 with positive direct-current bus 4-1 respectively with following brachium pontis.

Described master controller 1 comprises the unit A 1-1 that averages, the unit B of averaging 1-2, their input is connected with modular multilevel converter 4 outputs, output then is connected with last/following bridge arm balance controller 1-4 with the unit C 1-3 that averages respectively, the output of unit C 1-3 of averaging is connected with total capacitance voltage controller 1-6, on/following bridge arm balance controller 1-4 output is connected with multiplier I1-7, and multiplier I1-7 also is connected with normalization unit AN1-5; Total capacitance voltage controller 1-6 is connected with arithmetic element A1-8, arithmetic element B1-9 respectively with multiplier I1-7, and circulation unit 1-12 also is connected with arithmetic element A1-8, arithmetic element B1-9 simultaneously; The output of arithmetic element A1-8, arithmetic element B1-9 connects with corresponding current controller AN1-10, current controller AP1-11 respectively; Submodule dc bus capacitor reference voltage is sent into total capacitance voltage controller 1-6 input; The phase supply voltage of modular multilevel converter 4 is sent into normalization unit AN1-5; Last brachium pontis electric current is sent into current controller AP1-11, and following brachium pontis electric current is sent into current controller AN1-10.

It is described that upward brachium pontis controller 2 is identical with following brachium pontis controller 3 structures, wherein:

The described brachium pontis controller 2 of going up comprises with each and goes up the individual sub-module capacitance voltage detecting value u of brachium pontis N _Ap1, u _Apj... and u _ApNCorresponding fine setting controller AP1 2-1, fine setting controller APj2-2 ... fine setting controller AP (N-1) 2-3; Each finely tune controller AP output respectively with corresponding multiplier AP1 2-5, multiplier APj2-6 ... multiplier AP (N-1) 2-7 connects; Simultaneously respectively finely tuning controller AP output also is connected with adder AP2-11, adder AP2-11 is connected with opposite sign device AP2-12, multiplier APN2-13 successively, the output of each multiplier AP and corresponding adder AP1 2-8 ... adder APj2-9 ... adder AP (N-1) 2-10 ... adder APN2-14 connects; Last brachium pontis current detection value i _ApSend into normalization unit AP 2-4, normalization unit AP 2-4 and each multiplier AP12-5 ... multiplier APN2-13 connects;

Described brachium pontis controller 3 down comprises and each time brachium pontis N sub-module capacitance voltage detecting value u _An1, u _Anj... and u _AnNCorresponding fine setting controller AN13-1, fine setting controller ANj3-2 ... fine setting controller AN (N-1) 3-3; Each finely tune controller AN output respectively with corresponding multiplier AN13-5, multiplier ANj3-6 ... multiplier AN (N-1) 3-7 connects; Simultaneously respectively finely tuning controller AN output also is connected with adder AN3-11, adder AN3-11 is connected with opposite sign device AN3-12, multiplier ANN3-13 successively, the output of each multiplier AN and corresponding adder AN13-8 ... adder ANj3-9 ... adder AN (N-1) 3-10 ... adder ANN3-14 connects; Following brachium pontis current detection value i _AnSend into normalization unit AN3-4, normalization unit AN3-4 and each multiplier AN13-5 ... multiplier ANN3-13 connects.

Wherein,

Representation module multi-level converter positive direct-current busbar voltage,

The negative DC bus-bar voltage of expression, Mpj, Mnj represent respectively j submodule of upper and lower brachium pontis (j=1,2 ..., N), u _SaRepresentation module multi-level converter AC side a phase supply voltage, u _SauExpression and u _SaThe amplitude of frequency homophase is 1 AC signal together, i _Sa, i _ApAnd i _AnRepresentation module multi-level converter AC side a phase current and a go up brachium pontis electric current, a mutually and descend brachium pontis electric current, i mutually respectively _Sa ^*, i _Ap ^*And i _An ^*Representation module multi-level converter AC side a phase reference current and a go up brachium pontis reference current, a mutually and descend brachium pontis reference current, i mutually respectively ₀ ^*The voltage-controlled output of expression total capacitance, i _ApuExpression and current i _ApWith the unit amplitude electric current of frequency homophase, i _AnuExpression and current i _AnWith the unit amplitude electric current of frequency homophase, Δ i _ACFor last/following bridge arm balance is adjusted electric current, I _ACMIn the expression/and the output of following bridge arm balance controller, u _Dc ^*Be submodule dc bus capacitor reference voltage, u _ApjThe individual sub-module capacitance voltage of brachium pontis j in the expression (j=1,2 ..., N detected value, u _AnjThe individual sub-module capacitance voltage of brachium pontis j under the expression (j=1,2 ..., N) detected value,

Each submodule overall average capacitance voltage of expression upper and lower bridge arm,

Brachium pontis submodule average capacitor voltage in the expression,

Expression is brachium pontis submodule average capacitor voltage down, d _ApThe public duty ratio of brachium pontis PWM in the expression, d _AnExpression is the public duty ratio of brachium pontis PWM down, d _ApjJ submodule PWM of brachium pontis duty ratio in the expression (j=1,2 ..., N), d _AnjJ submodule PWM of brachium pontis duty ratio under the expression (j=1,2 ..., N), Δ d _ApjJ submodule fine setting of brachium pontis duty ratio in the expression (j=1,2 ..., N), Δ d _AnjJ submodule fine setting of brachium pontis duty ratio under the expression (j=1,2 ..., N), D _MpjFor the output valve of j fine setting controller of last brachium pontis (j=1,2 ..., N), D _MnjFor the following output valve of j fine setting controller of brachium pontis (j=1,2 ..., N), u _ApGo up each submodule of brachium pontis for a mutually and export total voltage switch periods mean value, u _AnExport total voltage switch periods mean value for a descends each submodule of brachium pontis mutually, L represents inductance, and C represents electric capacity.

Among Fig. 3, each submodule capacitance voltage detected value of unit A 1-1 input and last brachium pontis u averages _Ap1, u _Ap2..., u _ApNLink to each other, output not only links to each other with the input of the unit C 1-3 that averages, and also an input with last/following bridge arm balance controller 1-4 links to each other.The unit B of averaging 1-2 input and each submodule capacitance voltage detected value of following brachium pontis u _An1, u _An2..., u _AnNLink to each other, output not only links to each other with another input of the unit C 1-3 that averages, and also another input with last/following bridge arm balance controller 1-4 links to each other.Two inputs of total capacitance voltage controller 1-6 respectively with output and the electric capacity reference voltage u of the unit C 1-3 that averages _Dc ^*Link to each other, the input of output and arithmetic element A 1-8 and the input of arithmetic element B 1-9 link to each other.Normalization unit AN 1-5 input and AC side supply voltage u _SaLink to each other, output links to each other with the input of multiplier l 1-7.Another input of multiplier l 1-7 links to each other with the output of last/following bridge arm balance controller 1-4, and the input of output and arithmetic element A 1-8 and the input of arithmetic element B 1-9 link to each other.The output of circulation unit 1-12 links to each other with another input of arithmetic element A 1-8 and another input of arithmetic element B 1-9.The remaining input of arithmetic element A 1-8 with after the remaining input of arithmetic element B 1-9 links to each other also with AC side reference current i _Sa ^*Link to each other.The input of the output of arithmetic element A 1-8 and current controller AP 1-11 links to each other, and the input of the output of arithmetic element B 1-9 and current controller AN 1-10 links to each other.Another input of current controller AP 1-11 and last brachium pontis current feedback input variable i _ApLink to each other output d _ApLink to each other with last brachium pontis controller 2 (referring to Fig. 2).Another input of current controller AN1-10 and following brachium pontis current feedback input variable i _AnLink to each other output d _AnLink to each other with following brachium pontis controller 3 (referring to Fig. 2).

Among Fig. 4 fine setting controller AP1 2-1, fine setting controller APj 2-2, fine setting controller AP (N-1) 2-3 have identical structure and all have an input with

Link to each other, another input is respectively and each submodule capacitance voltage detected value of last brachium pontis u _Ap1, u _Apj, u _ApN-1Link to each other.The output of fine setting controller AP1 2-1, fine setting controller APj 2-2, fine setting controller AP (N-1) 2-3 links to each other with the input of multiplier AP1 2-5, multiplier APj 2-6, multiplier AP (N-1) 2-7 respectively, links to each other with the input of adder AP 2-11 simultaneously.The input of normalization unit AP 2-4 and last brachium pontis current i _ApLink to each other, output links to each other with another input of multiplier AP1 2-5, multiplier APj 2-6, multiplier AP (N-1) 2-3, links to each other with the input of multiplier APN2-13 simultaneously.The output of adder AP 2-11 links to each other with the input of opposite sign device AP 2-12.The output of opposite sign device AP 2-12 links to each other with another input of multiplier APN 2-13.The output of multiplier AP1 2-5, multiplier APj 2-6, multiplier AP (N-1) 2-7, multiplier APN 2-13 links to each other with the input of adder AP1 2-8, adder APj 2-9, adder AP (N-1) 2-10, adder APN 2-14 respectively.Another input of adder AP1 2-8, adder APj 2-9, adder AP (N-1) 2-10, adder APN 2-14 and the public duty ratio d of last brachium pontis PWM _ApLink to each other, output respectively with last brachium pontis PWM duty ratio d _Ap1, d _Apj, d _ApN-1, d _ApNLink to each other.

Among Fig. 5, fine setting controller AN1 3-1, fine setting controller ANj 3-2, fine setting controller AN (N-1) 3-3 have identical structure and all have an input with

Link to each other, another input is respectively and each submodule capacitance voltage detected value of following brachium pontis u _An1, u _Anj, u _AnNLink to each other.The output of fine setting controller AN1 3-1, fine setting controller ANj 3-2, fine setting controller AN (N-1) 3-3 links to each other with the input of multiplier AN1 3-5, multiplier ANj 3-6, multiplier AN (N-1) 3-7 respectively, links to each other with the input of adder AN 3-11 simultaneously.The input of normalization unit AN 3-4 and following brachium pontis current i _AnLink to each other, output links to each other with another input of multiplier AN1 3-5, multiplier ANj 3-6, multiplier AN (N-1) 3-7, links to each other with the input of multiplier ANN 3-13 simultaneously.The output of adder AN 3-11 links to each other with the input of opposite sign device AN 3-12.The output of opposite sign device AN 3-12 links to each other with another input of multiplier ANN 3-13.The output of multiplier AN1 3-5, multiplier ANj3-6, multiplier AN (N-1) 3-7, multiplier ANN 3-13 links to each other with the input of adder AN1 3-8, adder ANj 3-9, adder AN (N-1) 3-10, adder ANN 3-14 respectively.Another input of adder AN1 3-8, adder ANj 3-9, adder AN (N-1) 3-10, adder ANN 3-14 and the public duty ratio d of following brachium pontis PWM _AnLink to each other, output respectively with following brachium pontis PWM duty ratio d _An1, d _Anj, d _AnN-1, d _AnNLink to each other.

Among Fig. 6, be example mutually with M.Complex control system unit l 9, complex control system unit k 10, complex control system unit M 11 have identical structure and its input links to each other with the 1st phase, k phase, the M of M phase module multi-level converter 8 respectively, and its output all links to each other with M phase pwm signal generator 7.Complex control system unit k 10 has identical structure with complex control system unit 6, and M phase module multi-level converter 8 is made of M modular multilevel converter 4, and positive direct-current bus 4-1, negative dc bus 4-2 link to each other respectively.

The integrated control method of a kind of modular multilevel converter of the present utility model, by each submodule capacitance voltage of the upper and lower brachium pontis of detection module multi-level converter, upper and lower brachium pontis electric current, and the AC side supply voltage, through obtaining the public duty ratio of upper and lower brachium pontis PWM after the master controller calculation process; Go up each submodule capacitance voltage of (descending) brachium pontis and the public duty ratio of above-mentioned (descending) the brachium pontis PWM of going up through last (descending) brachium pontis controller calculation process, obtain the PWM duty ratio of (descending) each submodule of brachium pontis; The PWM duty ratio process pwm signal generator of each submodule produces the pwm control signal of each submodule, realizes electric current, the voltage control of each submodule capacitance voltage Balance Control and converter.

Its concrete steps are:

(1), obtains brachium pontis N sub-module capacitance voltage detecting value u by each N of brachium pontis on the detection module multi-level converter sub-module capacitance voltage _Ap1, u _Ap2... and u _ApN,, obtain brachium pontis submodule average capacitor voltage by the unit A that averages

By each N of brachium pontis under the detection module multi-level converter sub-module capacitance voltage, obtain down brachium pontis N sub-module capacitance voltage detecting value u _An1, u _An2... and u _AnN,, obtain down brachium pontis submodule average capacitor voltage by the unit B of averaging

With the above-mentioned brachium pontis submodule average capacitor voltage of going up With following brachium pontis submodule average capacitor voltage Be sent to the unit C that averages, obtain upper and lower brachium pontis overall average capacitance voltage

(2) by detecting AC side supply voltage u _Sa, handle through normalization unit A, obtain corresponding unit amplitude supply voltage u _Sau

(3) with the overall average capacitance voltage

With Voltage Reference u _Dc ^*Be sent to the total capacitance voltage controller and handle, obtain total capacitance voltage control current i ₀ ^*

(4) will go up brachium pontis submodule and following brachium pontis submodule average capacitor voltage

With

Be sent to/following bridge arm balance controller handles the output valve I that obtains _ACMWith unit amplitude supply voltage u _SauAfter multiplying each other, multiplier l obtains/following bridge arm balance adjustment electric current Δ i _AC, i.e. Δ i _AC=I _ACMU _Sau

(5) with AC side power supply reference current i _Sa ^*, i ₀ ^*, Δ i _ACElectric current with the generation of circulation unit

Send into arithmetic element A and obtain the brachium pontis reference current

Promptly $i_{\mathrm{ap}}^{*}=\frac{1}{2}({i_{\mathrm{sa}}}^{*}+\mathrm{\&Delta;}{i}_{\mathrm{AC}})+{i_0}^{*}+i_{\mathrm{aL}}^{*};$

(6) with AC side power supply reference current i _Sa ^*, i ₀ ^*, Δ i _ACElectric current with the generation of circulation unit

Send into arithmetic element B and obtain down the brachium pontis reference current Promptly $i_{\mathrm{an}}^{*}=\frac{1}{2}({i_{\mathrm{sa}}}^{*}-\mathrm{\&Delta;}{i}_{\mathrm{AC}})-{i_0}^{*}-i_{\mathrm{aL}}^{*};$

(7) will go up brachium pontis current detection value i _ApWith reference current

Be sent to current controller AP and handle, obtain the public duty ratio d of brachium pontis PWM _Ap

(8) will descend brachium pontis current detection value i _AnWith reference current

Be sent to current controller AB and handle, obtain down the public duty ratio d of brachium pontis PWM _An

(9) will go up brachium pontis current detection value i _ApSend into the normalization unit AP and handle, obtain brachium pontis unit amplitude current i _ApuTo descend brachium pontis current detection value i _AnSend into normalization unit AN and handle, obtain down brachium pontis unit amplitude current i _Anu

(10) will

With last brachium pontis j sub-module capacitance voltage detecting value u _Apj, wherein, j=1,2 ..., N-1 is sent to j submodule fine setting of brachium pontis controller APj and handles the output D of fine setting controller APj _MpjThrough corresponding multiplier APj and i _ApuPass through corresponding adder APj and the public duty ratio d of last brachium pontis PWM after multiplying each other again _ApAddition obtains j submodule PWM of brachium pontis duty ratio d _Apj

(11) N-1 is gone up brachium pontis fine setting controller AP1, fine setting controller AP2 ... and the output D of fine setting controller AP (N-1) _Mp1, D _Mp2... and D _MpN-1Sue for peace after opposite sign device AP oppositely obtains D through adder AP _MpN, again with i _ApuAPN multiplies each other through multiplier, then with the public duty ratio d of last brachium pontis PWM _ApAddition obtains N submodule PWM of brachium pontis duty ratio d _ApN

(12) will

With following brachium pontis j sub-module capacitance voltage detecting value u _Anj, j=1 wherein, 2 ..., N-1 is sent to down j submodule fine setting of brachium pontis controller ANj and handles the output D of fine setting controller ANj _MnjThrough corresponding multiplier ANj and i _AnuPass through corresponding adder ANj and the public duty ratio d of following brachium pontis PWM after multiplying each other again _AnAddition obtains down j submodule PWM of brachium pontis duty ratio d _Anj

(13) with N-1 down brachium pontis fine setting controller AN1, fine setting controller AN2 ... and the output D of fine setting controller AN (N-1) _Mn1, D _Mn2... and D _MnN-1Sue for peace after opposite sign device AN oppositely obtains D through adder AN _MnN, again with i _AnuANN multiplies each other through multiplier, then with the public duty ratio d of following brachium pontis PWM _AnAddition obtains down N submodule PWM of brachium pontis duty ratio d _AnN

(14) with each submodule PWM duty ratio d _Ap1, d _Ap2... and d _ApNAnd d _An1, d _An2... and d _AnNBe sent to the PWM generator unit, produce the pwm control signal of each submodule.

Claims (3)

1. the complex control system of a modular multilevel converter, it is characterized in that, it comprises M phase module multi-level converter, and each phase module multi-level converter is connected with separately composite control apparatus, each composite control apparatus then with M mutually the pwm signal generator connect; Wherein, described each composite control apparatus structure is identical, comprises brachium pontis controller, master controller and following brachium pontis controller; The modular multilevel converter output terminal of each phase is connected with last brachium pontis controller, master controller and following brachium pontis controller input respectively; The output of master controller is exported the public duty ratio d of brachium pontis PWM respectively _ApTo last brachium pontis controller, output is the public duty ratio d of brachium pontis PWM down _AnArrive brachium pontis controller down; Last brachium pontis controller is connected with corresponding pwm signal generator mutually with following brachium pontis controller output end.

2. the complex control system of modular multilevel converter as claimed in claim 1, it is characterized in that, described master controller comprises the unit A that averages, the unit B of averaging, their input is connected with the modular multilevel converter output terminal, output then is connected with last/following bridge arm balance controller with the unit C that averages respectively, the output of unit C of averaging is connected with the total capacitance voltage controller, on/following bridge arm balance controller output end is connected with multiplier I, and multiplier I also is connected with normalization unit AN; The total capacitance voltage controller is connected with arithmetic element A, arithmetic element B respectively with multiplier I, and the circulation unit also is connected with arithmetic element A, arithmetic element B simultaneously; Arithmetic element A, arithmetic element B connect with corresponding current controller AN, current controller AP respectively; Submodule dc bus capacitor reference voltage is sent into total capacitance voltage controller input; The phase supply voltage of modular multilevel converter is sent into normalization unit AN; Following brachium pontis phase current is sent into current controller AN.

3. the complex control system of modular multilevel converter as claimed in claim 1 is characterized in that, described upward the brachium pontis controller is identical with following brachium pontis controller architecture, wherein:

The described brachium pontis controller of going up comprises with each and goes up the individual sub-module capacitance voltage detecting value u of brachium pontis N _Ap1, u _Apj... and u _ApNCorresponding fine setting controller AP1, fine setting controller APj ... fine setting controller AP (N-1); Each finely tune controller AP output respectively with corresponding multiplier AP1, multiplier APj ... multiplier AP (N-1) connects; Simultaneously respectively finely tuning controller AP output also is connected with adder AP, adder AP is connected with opposite sign device AP, multiplier APN successively, the output of each multiplier AP and corresponding adder AP1 ... adder APj ... adder AP (N-1) ... adder APN connects; Last brachium pontis current detection value i _ApSend into the normalization unit AP, normalization unit AP and each multiplier AP1 ... multiplier APN connects;

Described brachium pontis controller down comprises and each time brachium pontis N sub-module capacitance voltage detecting value u _An1, u _Anj... and u _AnNCorresponding fine setting controller AN1, fine setting controller ANj ... fine setting controller AN (N-1); Each finely tune controller AN output respectively with corresponding multiplier AN1, multiplier ANj ... multiplier AN (N-1) connects; Simultaneously respectively finely tuning controller AN output also is connected with adder AN, adder AN is connected with opposite sign device AN, multiplier ANN successively, the output of each multiplier AN and corresponding adder AN1 ... adder ANj ... adder AN (N-1) ... adder ANN connects; Following brachium pontis current detection value i _AnSend into normalization unit AN, normalization unit AN and each multiplier AN1 ... multiplier ANN connects.

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