CN111740629B - Flat control method for modularized multi-level matrix converter - Google Patents

Flat control method for modularized multi-level matrix converter Download PDF

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CN111740629B
CN111740629B CN202010571604.7A CN202010571604A CN111740629B CN 111740629 B CN111740629 B CN 111740629B CN 202010571604 A CN202010571604 A CN 202010571604A CN 111740629 B CN111740629 B CN 111740629B
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control
input side
bridge arm
matrix converter
bridge
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CN111740629A (en
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程启明
马信乔
江畅
赵淼圳
程尹曼
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Shanghai University of Electric Power
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Shanghai University of Electric Power
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Ac-Ac Conversion (AREA)
  • Inverter Devices (AREA)

Abstract

The invention relates to a flat control method for a modularized multi-level matrix converter, which comprises the following steps: 1) Establishing a corresponding M3C mathematical model according to the M3C circuit topological structure; 2) Performing double alpha beta 0 transformation on the mathematical model to obtain an M3C decoupling model comprising an input side decoupling model, an output side decoupling model, a bridge arm capacitor voltage and circulation decoupling model and a common mode voltage decoupling model; 3) Performing dq transformation on the input side decoupling model, and constructing an input side flattening control strategy based on the feedforward reference control quantity and the error feedback compensation quantity; 4) PI control is carried out on the output side decoupling model, bridge arm capacitor voltage and loop decoupling model, and the input side flattening control strategy, common mode voltage control, H-bridge submodule voltage equalizing control and carrier phase shifting modulation are combined to jointly complete the flattening control of M3C. Compared with the prior art, the invention has the advantages of accelerating global stability, no static difference in tracking, high dynamic performance and the like.

Description

Flat control method for modularized multi-level matrix converter
Technical Field
The invention relates to the technical field of power electronic control, in particular to a flat control method for a modularized multi-level matrix converter.
Background
The M3C (modular multilevel matrix converter, MMMC, modular multilevel matrix converter) is a bidirectional switch formed by connecting a plurality of H bridge units in series, and unlike a semiconductor switching device in a traditional matrix converter, the M3C has the advantages of complete modularization, simple expansion to a high voltage level, flexible control, good harmonic quality, good redundancy and the like, and is very suitable for a high-power wind energy conversion system due to the unique advantages.
Due to the characteristics of nonlinearity, strong coupling and the like of the M3C, the control of the M3C is very complex, and the development is extremely slow. Until now, the control research of M3C is still in the stage of starting theoretical research, and no mature application exists at home and abroad at present. Studies on M3C control are currently mainly: control of the M3C input side, control of the M3C capacitor voltage and bridge arm circulation, and control of the M3C output side. Many studies on the control of the M3C capacitor voltage have been made, such as the injection of a circulating current and the application of reactive power at the input side as proposed in paper A broad range of frequency control for the modular multilevel cascade converter based on triple star bridge-cells (MMCC-TSBC) published at the institute of IEEE energy conversion and the exposition; the paper DC circulating current for capacitor voltage balancing in modular multilevel matrix converter published in the 14 th European conference of power electronics and applications adds a capacitor voltage balancing algorithm and the like. For the control of the M3C input side, PI control methods are mainly adopted at present, for example, the double αβ0 transformation proposed in paper Fully decouple current control and energy balancing of the modular multilevel matrix converter published in the 15 th international conference of power electronics and motion control is used to separate the input side current, the output side current and the bridge arm circulation from 9 bridge arm currents, so as to realize decoupling control. However, the current at the input side has obvious defects in simulation and engineering practical use in a PI control mode, and is mainly characterized by low response speed, easy overshoot, poor dynamic performance and poor robustness of a control system, and once the parameters of the control system change or external perturbation occurs, the global stability of the system cannot be realized.
Disclosure of Invention
The invention aims to provide a flat control method for a modularized multi-level matrix converter, which not only can combine output side PI control, bridge arm capacitor voltage and loop current PI control, common mode voltage control, H-bridge submodule voltage equalizing control and carrier phase shifting modulation by constructing an input side flat control strategy of feedforward reference control quantity and error feedback compensation quantity, so that the robustness of the whole control system is improved, the current stabilizing speed of the input side is improved, and the advantages of no overshoot, no static error in tracking, high dynamic performance and the like can be realized.
The aim of the invention can be achieved by the following technical scheme:
a flat control method for a modular multilevel matrix converter, comprising the steps of:
step 1, establishing a corresponding mathematical model of the modularized multi-level matrix converter, namely an M3C mathematical model, according to the circuit topology structure of the modularized multi-level matrix converter.
The circuit topology structure of the modularized multi-level matrix converter comprises nine bridge arms, each bridge arm comprises an inductor and a plurality of H bridge submodules which are connected in series, each H bridge submodule comprises a direct current capacitor and an H full bridge which are connected in parallel, each H full bridge is composed of four IGBT anti-parallel diodes, and the input side and the output side of the modularized multi-level matrix converter are three-phase alternating current symmetrical systems.
The expression of the M3C mathematical model is:
wherein u is mx And i mx The input side three-phase voltage and current of the power grid of the modularized multi-level matrix converter are respectively, x is the label of the input side three-phase bridge arm, and x=a, b and c; r is R s For input-side line resistance, L s Inductance for the input side line; l (L) qb Bridge arm inductance of the modularized multi-level matrix converter; i.e gy The three-phase current of the output side of the modularized multi-level matrix converter is y, which is the label of the three-phase bridge arm of the output side, and y=r, s and t; r is R g L is a resistive load g Is an inductive load; n is the neutral point of the input side; n is the neutral point of the output side, u nN Is a common mode voltage; i.e xy Is xy bridge arm current, u xy The total output voltage of all H bridge submodules on the xy bridge arm is obtained; u (u) gy Is the output side voltage; i.e gy Is the output side current.
And 2, performing double alpha beta 0 transformation on the established mathematical model of the modularized multi-level matrix converter to obtain a decoupling model of the modularized multi-level matrix converter, wherein the decoupling model of the modularized multi-level matrix converter comprises an input side decoupling model, an output side decoupling model, a bridge arm capacitor voltage and circulation decoupling model and a common mode voltage decoupling model. Specifically:
and respectively carrying out double alpha beta 0 transformation on the input side three-phase voltage and the input side three-phase current of the modularized multi-level matrix converter, carrying out double alpha beta 0 transformation on the output side three-phase voltage and the output side three-phase current of the modularized multi-level matrix converter, and carrying out double alpha beta 0 transformation on the bridge arm capacitor voltage and the bridge arm current to obtain a decoupling model of the modularized multi-level matrix converter.
The expression of the input side decoupling model is:
the expression of the output side decoupling model is as follows:
the expression of the bridge arm capacitor voltage and loop decoupling model is as follows:
the common mode voltage decoupling model has the expression:
wherein u is mo 、i mo 、u go 、i go U respectively mx 、i mx 、u gy 、i gy Quantity in the alpha beta 0 coordinate, u mx And i mx Input side grid three-phase voltage and current of modularized multi-level matrix converter respectively, x is input side three-phase bridge arm label, x=a, b, c, u xy The total output voltage of all H bridge submodules on an xy bridge arm is y, the label of the three-phase bridge arm on the output side is y=r, s and t; i.e op 、u op I respectively xy And u xy The quantity after transformation of double alpha beta 0, o is the coordinate axis label of the alpha beta 0 coordinate system, and o=alpha, beta and 0; p is the coordinate axis index of the αβ0 coordinate system, and p=α, β, 0.
Step 3, dq conversion is carried out on the decoupling model of the input side, and an input side flattening control signal is determined based on the feedforward reference control quantity and the error feedback compensation quantity, so as to construct an input side flattening control strategy; specifically:
31 According to the decoupling model of the input side, establishing a mathematical model of the input side under the dq coordinate system to determine a corresponding feedforward reference control quantity and an error feedback compensation quantity;
32 Based on the feedforward reference control amount and the error feedback compensation amount, a corresponding input-side flattening control signal is determined.
Wherein, the expression of the mathematical model of the input side under the dq coordinate system is:
wherein:u respectively mo 、i mo 、u op D-axis component and q-axis component in dq coordinate system; u (u) mo 、i mo 、u op U respectively mx 、i mx 、u xy The quantity in the double alpha beta 0 coordinates, o is the coordinate axis label of the alpha beta 0 coordinate system, and o=alpha, beta and 0; p is the coordinate axis index of the αβ0 coordinate system, and p=α, β, 0; u (u) mx 、i mx Three-phase voltage, current, x=a, b, c, u of the input-side network of the modular multilevel matrix converter xy For the total output power of all H-bridge submodules on xy bridge armThe voltage, y is the label of the three-phase bridge arm of the output side, y=r, s, t;
the specific expression of the feedforward reference control quantity is as follows:
in the method, in the process of the invention,and->State variables +.>And->Reference value of->And->Respectively->Andis used for controlling the feedforward reference control quantity;
the specific expression of the error feedback compensation quantity is as follows:
in the method, in the process of the invention,and->The d-axis component and q-axis component of the system state variable error are expressed as:
and->State variable errors ∈>And->Reference value of->And->Respectively->And->Error feedback compensation amount k of (a) DFp 、k DFi PI parameters in the flat control respectively;
the specific expression of the input side flat control signal is as follows:
in the method, in the process of the invention,and->The d and q axis components of the input side flat control signal, respectively.
And 4, performing PI control on the output side decoupling model, the bridge arm capacitor voltage and the loop decoupling model, and jointly completing the flat control on the M3C by combining the input side flat control strategy, the common mode voltage control, the H-bridge submodule voltage equalizing control and the carrier phase shifting modulation in the step 3.
The specific content of PI control on the bridge arm capacitor voltage and loop decoupling model is as follows:
collecting the capacitance voltage of each bridge arm of the modularized multi-level matrix converter, establishing a power energy model, carrying out double alpha beta 0 conversion on the model, and adopting PI to control the capacitance voltage of the bridge arm; and collecting each bridge arm current of the modularized multi-level matrix converter, performing double alpha beta 0 conversion, and performing PI control on each bridge arm current.
The H-bridge submodule voltage equalizing control comprises the following specific contents: the capacitor voltage of the ith H-bridge sub-module of the xy bridge arm is independently controlled by collecting the current of the xy bridge arm and the capacitor voltage of the ith H-bridge sub-module of the xy bridge arm.
The specific contents of the carrier phase shift modulation are as follows: control signal SM using the kth H bridge sub-module of the xy bridge arm xyk * And triangular carrier xy k Modulating to obtain the trigger signal of the kth H bridge sub-module on the xy bridge arm.
Compared with the prior art, the invention has at least the following beneficial effects:
1) According to the method, the decoupling M3C equivalent model is combined, the input side decoupling model is subjected to flat control, when the input side is subjected to flat control, double alpha beta 0 conversion and dq conversion are mainly carried out on three-phase voltage and current of the input side according to a circuit topological structure, an input side flat control signal is determined based on feedforward reference control quantity and error feedback compensation quantity, an input side flat control strategy is constructed, the method is simple, quick in response, free of overshoot and static difference in tracking, and high in dynamic performance, and compared with the traditional PI control, the stability of the current of the input side is improved, so that the global stability is accelerated;
2) The invention effectively improves the response speed and the dynamic performance by constructing the input side flattening control strategy of the feedforward reference control quantity and the error feedback compensation quantity, has smaller impact on the system, enhances the robustness of the whole M3C control system, and can quickly realize global stability when the external parameters are perturbed;
3) The method designs the flat controller and d-axis and q-axis current closed-loop transfer functions based on differential flat theory, so that the output current can track the reference given value well, an inertia link does not exist, the response speed is very good, the d-axis and q-axis can realize independent decoupling control, and further, when the frequency of the input side changes and the load of the output side changes, the flat control strategy responds fast, has no overshoot and no static difference in tracking, has high dynamic performance, smaller impact on the system, and is simple to control and easy to realize.
Drawings
FIG. 1 is a control block diagram of the M3C input side of the method of the present invention;
FIG. 2 is a block diagram of a differential flatness theory based flatness control in the method of the present invention;
FIG. 3 is a schematic diagram of the circuit topology of M3C in an embodiment;
FIG. 4 is a simplified topology of M3C in an embodiment;
FIG. 5 is an overall control block diagram of the method of the present invention;
FIG. 6 is a schematic diagram of the flat control of the present invention;
FIG. 7 is a block diagram illustrating a bridge arm capacitor voltage control in accordance with the method of the present invention;
FIG. 8 is a schematic diagram of the bridge arm loop control of M3C of the method of the present invention;
FIG. 9 is a graph showing the comparison of the d-axis current at the input side of M3C under the flat control of the present invention and PI control in the example;
FIG. 10 is a waveform of M3C input and output under PI control in one embodiment;
FIG. 11 is a waveform of M3C input and output under flat control according to an embodiment of the present invention;
FIG. 12 is a graph illustrating the operating state of M3C under the flat control of the present invention in an embodiment;
FIG. 13 is a graph showing the comparison of the current of the d-axis of the input side of M3C under the flat control of the present invention with PI control when the frequency of the input side is changed in the embodiment;
FIG. 14 is a schematic diagram of M3C input and output waveforms under flat control according to the present invention when the input side frequency is changed in the embodiment;
FIG. 15 is a graph showing the comparison of the current on the d-axis of the input side of M3C under the flat control of the present invention with PI control when the load on the output side is changed in the embodiment;
fig. 16 is a schematic diagram of waveforms of M3C input and output under flat control according to the present invention when the load on the output side is changed in the embodiment.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Examples
Referring to fig. 1 to 16, a flat control method for a modular multilevel matrix converter is provided for an embodiment of the present invention. In this embodiment, the circuit topology of M3C is shown in fig. 3 and 4, and is composed of 9 bridge arms, each bridge arm is composed of k H bridge Sub-modules (Sub-modules, SMs) connected in series and then connected in series with an inductor L, each H bridge Sub-module is composed of an H full bridge and a dc capacitor C connected in parallel, each H full bridge is composed of 4 IGBT anti-parallel diodes T 1 ～T 4 Composition is prepared. The input side and the output side of the M3C are three-phase alternating current symmetrical systems, the input side is usually a three-phase symmetrical alternating current voltage source, the output side is generally connected with a motor, a resistive load or a power grid and the like, and the system can operate in four quadrants. In FIG. 3, u mx And i mx Three-phase voltages and currents (x=a, b, c) of the input-side network, R s 、L s For input side line impedance, SM xyi Is the ith H bridge submodule (y=r, s),t is; i=1, 2, …, k), k represents the number of H-bridge sub-modules of the bridge arm, each H-bridge sub-module having a capacitance, i.e. the number of capacitances is the same as the number of H-bridge sub-modules. i.e xy Is bridge arm current, L qb Is the inductance of bridge arm, i gy R is the three-phase current at the output side g 、L g For resistive loads, N, n is the neutral point.
The invention provides a flat control method for a modularized multi-level matrix converter, which mainly lists a mathematical model of M3C according to a circuit structure of M3C, performs double alpha beta 0 conversion on the mathematical model to obtain an M3C decoupling model, performs dq change on an input side decoupling model in the model, analyzes input side flatness under a dq coordinate system to determine input side flat control signals based on feedforward reference control quantity and error feedback compensation quantity, so as to obtain an input side flat control strategy of M3C, and then jointly realizes M3C integral control shown in figure 5 by combining output side PI control, bridge arm capacitor voltage and circulation PI control, common mode voltage control, H bridge submodule voltage equalizing control and carrier phase shifting modulation. The method of the invention realizes the flat control of M3C by the following contents:
s1, establishing a corresponding M3C mathematical model according to the circuit topological structure of the M3C.
S2, performing double alpha beta 0 transformation on the M3C mathematical model to obtain an M3C decoupling model, wherein the M3C decoupling model comprises an input side decoupling model, an output side decoupling model, a bridge arm capacitance voltage and circulation decoupling model and a common mode voltage decoupling model.
S3, performing dq conversion on the input side decoupling model, and determining an input side flattening control signal based on the feedforward reference control quantity and the error feedback compensation quantity to obtain an input side flattening control strategy;
and S4, PI control is carried out on the output side decoupling model, the bridge arm capacitor voltage and the loop decoupling model, and the input side flattening control, the common mode voltage control, the H-bridge submodule voltage equalizing control and the carrier phase shifting modulation are combined to jointly complete the flattening control of the M3C. Wherein:
a) Bridge arm capacitor voltage PI control: collecting capacitance voltage of each bridge arm of M3C, establishing a power energy model, performing double alpha beta 0 conversion, and adopting PI control;
b) Bridge arm loop current PI control: collecting the current of each bridge arm of M3C, performing double alpha beta 0 conversion, and performing PI control on the double alpha beta 0 conversion;
the power energy model is deduced according to the power-capacitance mathematical model of M3C, and the main process is as follows:
for M3C, the total voltage u of the k capacitances of the xy bridge arm is noted cxy The method comprises the following steps:
then, it is possible to obtain:
wherein u is cxyi Is the capacitance voltage value in the ith H bridge submodule on the xy bridge arm.
And due to arm energy W xy The method comprises the following steps:
wherein, C is the capacitance value of the DC capacitor.
Neglecting internal losses and losses of bridge arm inductances, there are:
thus, it is possible to obtain:
in U dc The voltage of the capacitor at the direct current side, namely the capacitor voltage stabilizing value; p (P) xy Is the power of k capacitors on the xy bridge arm.
The above two-sided integral can be obtained:
can be regarded asWherein->Represents the mean component>Representing a ripple component; the double αβ0 transform of the above formula is:
on the other hand:
wherein,,the rest of the same principle can be found.
Let u be ma ＝u m cos(ω m t+δ)；u gr ＝u g cos(ω mg t)；u m 、i m The amplitude of the voltage and the current of the power grid at the input side of M3C; u (u) g 、i g Amplitude of voltage and current at the output side of M3C; omega m ＝2πf i For M3C input side angular frequency, ω g ＝2πf o And the output side angular frequency is M3C. f (f) i And f o The M3C input side frequency and the output side frequency, respectively. />And->The input side and output side phase angles, respectively, δ is the initial phase of the input side relative to the output side of t=0.
The formula (8) is obtained by performing double αβ0 conversion on the formula (5), sorting, substituting the formula (4) by the "design circulation" method of the formulas (6) and (7), and filtering out the ripple component. And (3) the following steps:
in the formula (8), u cop Is u cxy The amount after transformation by the double alpha beta 0,is u cop The amounts of ripple components are filtered out, and the amounts in the formulas (6) and (7) can be substituted by the amounts in the formula (8). Wherein i is op1ref Is the circulation reference value i inside the bridge arm capacitor op2ref Is a reference value for the loop current between the bridge arm capacitors. I d1 And I q1 Respectively is I αα1ref A sine component and a cosine component of (a); i d2 And I q2 Respectively is I αβ1ref Cosine and sine components of (a); i d3 And I d6 Respectively is I αβ2ref A net side sine component and a machine side cosine component; i d4 And I d6 Respectively is I ββ2ref Is on the net side of (2)Sinusoidal components and machine side sinusoidal components.
Equation (8) is a mathematical model of bridge arm capacitance voltage control, and a control block diagram thereof is shown in fig. 7.
And (3) the following steps:
the bridge arm circulation control law of M3C can be obtained by combining the formula (6), the formula (7) and the formula (9), as shown in figure 8.
The above shows the control of bridge leg circulation by injection circulation (i.e. the "design circulation" method) according to the power energy model of M3C.
c) Input side flattening control: collecting voltage and current of an M3C input side, establishing a mathematical model, transforming alpha beta 0, transforming dq, and designing a system flat controller based on feedforward reference control quantity and error feedback compensation quantity, thereby obtaining a flat control strategy of the M3C;
d) Output-side PI control: collecting voltage and current of an M3C output side, establishing a mathematical model, and obtaining an M3C output side control model through alpha beta 0 transformation and dq transformation;
e) Common mode voltage control: the invention does not consider the injection common-mode voltage, i.e. injection common-mode voltage u * 00 ＝0；
f) Equalizing control of the H bridge submodule: collecting current on an xy bridge arm and capacitance voltage of an ith H bridge sub-module on the xy bridge arm, and independently controlling the capacitance voltage of the ith H bridge sub-module on the xy bridge arm;
g) Carrier phase-shift modulation: using a control signal and a triangular carrier wave to control the control signal SM of the kth H bridge sub-module of the xy bridge arm xyk * And triangular carrier xy k Modulating to obtain a trigger signal of a kth H bridge sub-module on the xy bridge arm.
Specifically, when input-side flattening control is performed, the main process is as follows:
from the circuit topology of fig. 3, it is possible to obtain from Kirchhoff's Voltage Law:
wherein: u (u) mx 、i mx Three-phase voltage and current (x=a, b and C) of the power grid at the input side of M3C respectively; r is R s 、L s Respectively M3C input side impedance; l (L) qb The inductance is M3C bridge arm inductance; i.e xy 、u xy The current of the xy bridge arm of M3C and the total capacitance voltage (y=r, s, t) of k H bridge sub-modules on the xy bridge arm respectively; u (u) nN Is a common mode voltage. u (u) gy Is the output side voltage; i.e gy R is the output side current g L is a resistive load g Is an inductive load.
The double alpha beta 0 transformation is carried out on the formula, and the calculation and the arrangement are carried out to obtain the product:
wherein: u (u) mz 、i mz 、u gz U respectively mx 、i mx 、u gy The amount in αβ0 coordinates (z=α, β, 0); i.e zz 、u zz I respectively xy And u xy Amount transformed by double αβ0.
Therefore, the decoupling equivalent model of M3C can be obtained as:
among the above models, the input side decoupling model is:
the output side decoupling model is:
the bridge arm capacitance voltage and loop decoupling model is as follows:
the common-mode voltage decoupling model is:
in the above, u mo 、i mo 、u go 、i go U respectively mx 、i mx 、u gy 、i gy Quantity in the alpha beta 0 coordinate, u mx And i mx Input side grid three-phase voltage and current of modularized multi-level matrix converter respectively, x is input side three-phase bridge arm label, x=a, b, c, u xy The total output voltage of all H bridge submodules on an xy bridge arm is y, the label of the three-phase bridge arm on the output side is y=r, s and t; i.e op 、u op I respectively xy And u xy The quantity after transformation of double alpha beta 0, o is the coordinate axis label of the alpha beta 0 coordinate system, and o=alpha, beta and 0; p is the coordinate axis index of the αβ0 coordinate system, and p=α, β, 0.
At the same time, it is also possible to obtain:
then, according to the circuit topology of fig. 3, the following kirchhoff current theorem is obtained:
the above formula is transformed by αβ0, namely, the following steps:
after calculation and arrangement, the method can be as follows:
thus, the combination of the formulaThe method can obtain:
i mα ＝i αr +i αs +i αt
from the above formulaThe method can obtain:
then the same principle can be obtained:
/>
the above 4 equations are substituted:
the method can obtain:
according toThe mathematical model of the input side of the available M3C in the dq coordinate system is:
wherein:u respectively mz 、i mz 、u zz In dq coordinatesd-axis component and q-axis component.
Thereby obtaining the PI control law of the M3C input side according to the above formula:
wherein:respectively->Is included in the reference value of (2).
The flatness and stability of the input side are demonstrated below based on a two-phase rotational coordinate system.
According to
For convenience of deduction, recordThen it is obtainable by the formula:
from the above equation, the nonlinear system satisfies differential flattening theory, and there are 2 input variables u that are not considerable in the system 1 And u 2 The output variable y is required to be made 1 And y 2 Satisfy y 1 →y 1ref And y 2 →y 2ref Thereby achieving progressive tracking of its desired trajectory.
The output variable proportion-integral error is:
with the goal of global progressive stabilization of the system, an energy equation for the M3C system is designed as follows:
when the above formula satisfies the initial condition (i.e., e=0, E (0) = 0;e +.0, E > 0), the derivative of the above formula can be obtained:
the above formula can be represented by the formulaA kind of->The expression is as follows:
for a differential flattening system of M3C, when e+.0 and E>At 0, it is required to satisfyThe system can be enabled to realize E-0 when E-0, so that the total energy of the system is reduced to be globally stable along the expected track.
Thus, there are:
/>
wherein: l (L) eq ＝(3L s +L qb )。
Substituting the control input into the above formulaIn (2), can be obtained:
wherein: lambda (lambda) 1 >0，λ 2 >0, which are all the system control gains, is lambda 1 ＝λ 2 ＝ω m 。
The flat control system is proven to be stable.
According to differential flattening theory, strictly flattening systems must employ flattening control and control systems are stable.
The planar controller is designed based on a two-phase rotation coordinate system.
According toThe controller feedforward reference input control quantity of the available flattening control is as follows:
wherein:and->State variables +.>And->Is a reference value of (2); />And->Respectively->Andis used for controlling the feedforward reference control quantity;
let the system state variable error be:
substituting the above formula into the following formula:
an error model is available:
the error feedback compensation value obtained according to the above is:
wherein: k (k) DFp And k DFi PI control parameters for a flat controller;and->State variable errors ∈>And->Is a reference value of (2); />And->Respectively->And->Error feedback compensation amount of (a).
To eliminate errors, letThe reference input control amount based on the flat controller is then:
simultaneous up and down typeThe method can obtain:
the d-axis current and q-axis current closed loop transfer functions obtained by the method are as follows:
the output current of the M3C flat controller designed based on differential flat theory can track the reference given value well, no inertia links exist, the response speed is very good, and the d and q axes can realize independent decoupling control.
Thus, a flat control block diagram of M3C can be obtained, as shown in fig. 1 and 2.
In order to verify the effectiveness of the flat control method adopted by the M3C provided by the invention, the embodiment builds an M3C control system on a MATLAB/Simulink software platform, and simulates the operation conditions of input side frequency conversion and output side load conversion. The main parameters of the system are shown in table 1.
TABLE 1 System principal parameters
/>
The PI control strategy is compared with the flat control strategy, and the effectiveness and the correctness of the method are verified through theoretical analysis, deduction and software simulation, and the specific implementation effects are as follows:
fig. 9 to 12 show various output waveforms of M3C in the flattening control method of the present invention, in which: FIG. 9 is the current on the d-axis of the input side three-phase current of M3C under flat control and PI control; FIG. 10 is a waveform of M3C input and output under PI control; FIG. 11 is a waveform of M3C input and output under the flattening control of the present invention; fig. 12 is an operation state of M3C under the flat control. As can be seen from fig. 9, the input side current stabilizing speed is faster, tracking is free from static difference and overshoot, and the control effect is better when adopting the flat control.
Fig. 13 to 14 show various output waveforms of M3C when the analog input side frequency is changed. At 0.1s, the input side frequency is increased from 16.7Hz to 50Hz, at which time k is a flat control strategy DFp ＝197，k DFi =7, K in pi control strategy p1 ＝233，K i1 =8; at 0.2s, the input side frequency is reduced from 50Hz to 16.7Hz, and at this time k is the flat control strategy DFp ＝403，k DFi =11, K in pi control strategy p1 ＝419，K i1 =10. Fig. 13 and 14 are respectively the current on the d-axis of the input side three-phase current of M3C, the waveforms of the input and output of M3C, and the waveforms of the input and output of M3C under the flat control of the present invention.
As can be seen from fig. 13, when the input side frequency is changed, the input side current is stabilized faster, without overshoot, without static error in tracking, with high dynamic performance and better control effect when adopting the flat control.
At 0.1s, load R1 is added to the output side 1 ＝30Ω，L 1 Load r=0.05h and No. 2 2 ＝20Ω，L 2 =0.03h, and at this time k in the flat control strategy DFp ＝101，k DFi =5, K in pi control strategy p1 ＝317，K i1 =8; at 0.2s, the output side cuts off load No. 1, and at this time k in the flat control strategy DFp ＝61，k DFi =4, K in pi control strategy p1 ＝155，K i1 =6. The input frequency is 50/3Hz, and the output frequency is 50Hz.
Fig. 15 to 16 show various output waveforms of M3C when the analog output side load suddenly fluctuates. Wherein: FIG. 15 is the current on the d-axis for the input side three-phase current of M3C; fig. 16 is a waveform of input and output of M3C under the flattening control of the present invention. As can be seen from fig. 15, when the load on the output side changes, the current on the input side responds quickly, without overshoot, with smaller impact on the system, high dynamic performance and better control effect when adopting the flat control.
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions may be made without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (8)

1. A flat control method for a modular multilevel matrix converter, comprising the steps of:
1) Establishing a corresponding mathematical model of the modularized multi-level matrix converter according to the circuit topological structure of the modularized multi-level matrix converter;
2) Performing double alpha beta 0 transformation on the established mathematical model of the modularized multi-level matrix converter to obtain a decoupling model of the modularized multi-level matrix converter, wherein the decoupling model of the modularized multi-level matrix converter comprises an input side decoupling model, an output side decoupling model, a bridge arm capacitor voltage and circulation decoupling model and a common mode voltage decoupling model;
3) Performing dq conversion on the input side decoupling model, determining an input side flattening control signal based on a feedforward reference control quantity and an error feedback compensation quantity, and constructing an input side flattening control strategy;
4) PI control is carried out on the output side decoupling model, bridge arm capacitor voltage and loop decoupling model, and the input side flattening control strategy, common-mode voltage control, H-bridge submodule voltage equalizing control and carrier phase shifting modulation of the step 3) are combined to jointly complete flattening control on M3C;
the specific content of the input side flattening control strategy constructed in the step 3) is as follows:
31 According to the decoupling model of the input side, establishing a mathematical model of the input side under the dq coordinate system to determine a corresponding feedforward reference control quantity and an error feedback compensation quantity;
32 Determining a corresponding input side flattening control signal based on the feedforward reference control amount and the error feedback compensation amount;
the expression of the mathematical model of the input side in the dq coordinate system is:
wherein:u respectively mo 、i mo 、u op D-axis component and q-axis component in dq coordinate system; u (u) mo 、i mo 、u op U respectively mx 、i mx 、u xy The quantity in the double alpha beta 0 coordinates, o is the coordinate axis label of the alpha beta 0 coordinate system, and o=alpha, beta and 0; p is the coordinate axis index of the αβ0 coordinate system, and p=α, β, 0; u (u) mx 、i mx Input-side power grid three-phase power of modularized multi-level matrix converterVoltage, current, x=a, b, c, u xy The total output voltage of all H bridge submodules on an xy bridge arm is y, the label of the three-phase bridge arm on the output side is y=r, s and t;
the specific expression of the feedforward reference control quantity is as follows:
in the method, in the process of the invention,and->State variables +.>And->Reference value of->And->Respectively->And->Is used for controlling the feedforward reference control quantity;
the specific expression of the error feedback compensation quantity is as follows:
in the method, in the process of the invention,and->The d-axis component and q-axis component of the system state variable error are expressed as:
and->State variable errors ∈>And->Reference value of->And->Respectively->Anderror feedback compensation amount k of (a) DFp 、k DFi PI parameters in the flat control respectively;
the specific expression of the input side flat control signal is as follows:
in the method, in the process of the invention,and->The d and q axis components of the input side flat control signal, respectively.
2. The planar control method for a modular multilevel matrix converter according to claim 1, wherein in step 1), the circuit topology of the modular multilevel matrix converter includes nine bridge arms, each bridge arm includes one inductor and a plurality of H-bridge submodules connected in series, each H-bridge submodule includes one dc capacitor and one H-full bridge connected in parallel, each H-full bridge is composed of four IGBT antiparallel diodes, and the input side and the output side of the modular multilevel matrix converter are all three-phase ac symmetrical systems.
3. The flat control method for a modular multilevel matrix converter according to claim 2, wherein in step 4), the specific contents of the H-bridge submodule voltage equalizing control are:
the capacitor voltage of the ith H-bridge sub-module of the xy bridge arm is independently controlled by collecting the current of the xy bridge arm and the capacitor voltage of the ith H-bridge sub-module of the xy bridge arm.
4. The flat control method for a modular multilevel matrix converter according to claim 2, wherein the specific contents of the carrier phase shift modulation are:
control signal SM using the kth H bridge sub-module of the xy bridge arm xyk * And triangular carrier xy k Modulating to obtain the trigger signal of the kth H bridge sub-module on the xy bridge arm.
5. The flat control method for a modular multilevel matrix converter according to claim 2, wherein in step 1), the expression of the mathematical model of the modular multilevel matrix converter is:
wherein u is mx And i mx The input side three-phase voltage and current of the power grid of the modularized multi-level matrix converter are respectively, x is the label of the input side three-phase bridge arm, and x=a, b and c; r is R s For input-side line resistance, L s Inductance for the input side line; l (L) qb Bridge arm inductance of the modularized multi-level matrix converter; i.e gy The three-phase current of the output side of the modularized multi-level matrix converter is y, which is the label of the three-phase bridge arm of the output side, and y=r, s and t; r is R g L is a resistive load g Is an inductive load; n is the neutral point of the input side; n is the neutral point of the output side, u nN Is a common mode voltage; i.e xy Is xy bridge arm current, u xy The total output voltage of all H bridge submodules on the xy bridge arm is obtained; u (u) gy Is the output side voltage; i.e gy Is the output side current.
6. The flat control method for a modular multilevel matrix converter according to claim 5, wherein the specific contents of step 2) are:
and respectively carrying out double alpha beta 0 transformation on the input side three-phase voltage and the input side three-phase current of the modularized multi-level matrix converter, carrying out double alpha beta 0 transformation on the output side three-phase voltage and the output side three-phase current of the modularized multi-level matrix converter, and carrying out double alpha beta 0 transformation on the bridge arm capacitor voltage and the bridge arm current to obtain a decoupling model of the modularized multi-level matrix converter.
7. The flat control method for a modular multilevel matrix converter according to claim 5, wherein the expression of the input side decoupling model is:
the expression of the output side decoupling model is as follows:
the expression of the bridge arm capacitor voltage and loop decoupling model is as follows:
the common mode voltage decoupling model has the expression:
wherein u is mo 、i mo 、u go 、i go U respectively mx 、i mx 、u gy 、i gy Quantity in the alpha beta 0 coordinate, u mx And i mx Input side grid three-phase voltage and current of modularized multi-level matrix converter respectively, x is input side three-phase bridge arm label, x=a, b, c, u xy The total output voltage of all H bridge submodules on an xy bridge arm is y, the label of the three-phase bridge arm on the output side is y=r, s and t; i.e op 、u op I respectively xy And u xy The quantity after transformation of double alpha beta 0, o is the coordinate axis label of the alpha beta 0 coordinate system, and o=alpha, beta and 0; p is the coordinate axis index of the αβ0 coordinate system, and p=α, β, 0.
8. The flat control method for a modular multilevel matrix converter according to claim 1, wherein in step 4), the specific content of PI control on the bridge arm capacitor voltage and the loop decoupling model is:
collecting the capacitance voltage of each bridge arm of the modularized multi-level matrix converter, establishing a power energy model, carrying out double alpha beta 0 conversion on the model, and adopting PI to control the capacitance voltage of the bridge arm; and collecting each bridge arm current of the modularized multi-level matrix converter, performing double alpha beta 0 conversion, and performing PI control on each bridge arm current.
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CN112671249A (en) * 2020-12-30 2021-04-16 国网河北省电力有限公司沧州供电分公司 M3C control method and terminal equipment
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CN114123805B (en) * 2021-11-23 2024-04-02 西安交通大学 Capacitive dynamic voltage-sharing control method of modularized multi-level matrix converter
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110868091A (en) * 2018-08-28 2020-03-06 南京理工大学 Nonlinear control method of vehicle-mounted charger PFC converter based on differential flatness
CN111211562A (en) * 2019-11-13 2020-05-29 上海电力大学 MMC-UPQC passive control method based on power grid voltage unbalance condition

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110868091A (en) * 2018-08-28 2020-03-06 南京理工大学 Nonlinear control method of vehicle-mounted charger PFC converter based on differential flatness
CN111211562A (en) * 2019-11-13 2020-05-29 上海电力大学 MMC-UPQC passive control method based on power grid voltage unbalance condition

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
A Decoupled Control Strategy of Modular Multilevel Matrix Converter for Fractional Frequency Transmission System;Shenquan Liu等;《IEEE TRANSACTIONS ON POWER DELIVERY》;第32卷(第04期);2111-2121 *
基于微分平坦理论的模块化多电平换流器控制器设计;宋平岗 等;《电网技术》;第37卷(第12期);3475-3481 *
模块化多电平换流器功率平坦控制策略;宋平岗 等;《电网技术》;第40卷(第02期);563-570 *

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