The control letter of modularization multi-level converter based on two level SVPWM modulator approaches
Change method
Technical field
The invention belongs to power electronics field, more particularly to a kind of module based on two level SVPWM modulator approaches
The control for changing multilevel converter simplifies method.
Background technology
Relatively traditional UHV AC transmission technique, HVDC Transmission Technology big, power transmission distance, line loss with transmission capacity
The advantages that low, construction investment saves, corridor utilization rate is high, the method for operation is flexible, so that extra-high voltage direct-current transmission engineering is in state
Extensive concern and development are inside obtained.It is straight using the flexibility of insulated gate bipolar transistor IGBT in HVDC Transmission Technology
Flowing technology of transmission of electricity need not be a large amount of idle, can be had broad application prospects in field of power transmission with effectively save cost and space,
But due to being limited by IGBT power so that flexible DC power transmission engineering is difficult to realize high capacity transmission, to a certain degree
On limit the development of the technology.With being constantly progressive for science and technology, the trend that IGBT power is inevitable, flexible direct current are improved
Technology of transmission of electricity will replace traditional HVDC Transmission Technology, become the following main power transmission mode.Modularization multi-level converter
It is the research emphasis that also will be future now as a ring mostly important in flexible DC transmission technology.
Space vector pulse width modulation (Space Vector Pulse Width Modulation, SVPWM) relies on it
The advantage that switching loss is low, waveform quality is good, DC voltage utilization rate is high is widely used in the control of converters
Field is concentrated mainly on two level and three level, it is difficult to it is applied to higher level, reason is the increase with level number,
Voltage vector space diagram can become sufficiently complex, be not easy digitlization reality.Therefore, in modularization multi-level converter (Modular
Multilevel converter, MMC) control field it is also fewer about the research of SVPWM technologies.Based on above-mentioned point
Analysis, if the simplification SVPWM technologies of MMC control fields can be obtained, that will make full use of the excellent of SVPWM technologies and MMC structures
Point is widely applied in flexible DC power transmission, high-pressure frequency-conversion or even power electronics transverter every field, will be one very
Significant research topic.
Invention content
In order to overcome the disadvantages of the above prior art, the present invention provides a kind of based on two level SVPWM modulator approaches
Modularization multi-level converter control simplifies algorithm, which simplifies the SVPWM method of modularization multi-level converter
At the combination of two level SVPWM modulator approaches and phase-shifting carrier wave modulator approach, algorithm is simple, versatile, and suitable for arbitrary
Level.
It realizes above-mentioned technical purpose, reaches above-mentioned technique effect, the invention is realized by the following technical scheme:
A kind of control simplification method of the modularization multi-level converter based on two level SVPWM modulator approaches, including with
Lower step:
Step 1: the single module of modularization multi-level converter is equivalent at concatenated upper bridge arm three-phase half-bridge and lower bridge arm
Three-phase half-bridge;
Step 2: establishing the SVPWM Controlling model equivalent with the SPWM Controlling models of modularization multi-level converter;Its
In, SPWM Controlling models include:Reference voltage control module, balancing energy control module, 2N capacitor voltage equalizing control module and
For output drive signal to 2N phase-shifted SPWM modulation module of modularization multi-level converter, the SVPWM controls
Phase-shifted SPWM modulation module in SPWM Controlling models is substituted for phase-shifting carrier wave 2D-SVPWM modulation modules, carrier wave by model
Phase shift 2D-SVPWM modulation modules include phase-shifting carrier wave modulation module and 2D-SVPWM generation modules, phase-shifting carrier wave 2D-SVPWM tune
The output signal value of molding block is restricted in [- 1,1] range, and N is the quantity of single module in modularization multi-level converter.
Step 3: the quantity of 2D-SVPWM generation modules is simplified to 2, and each 2D-SVPWM generation modules are moved to
Between balancing energy control module and capacitor voltage equalizing control module, while the output signal value of capacitor voltage equalizing control module being limited
It is substituted for phase-shifted SPWM modulation module into [- 1,1] range, and by phase-shifting carrier wave 2D-SVPWM modulation modules;
Step 4: the quantity of 2D-SVPWM generation modules is simplified to 1, and 2D-SVPWM generation modules are advanced to original
After reference voltage control module, new reference voltage control is collectively formed with former reference voltage control module in 2D-SVPWM generation modules
Molding block, in new reference voltage control module, the output signal of former reference voltage control module is output to 2D- after negating
SVPWM generation modules;The output signal value of energy equalization control module and capacitor voltage equalizing control module is restricted to simultaneously [- 1,
1] in range, the final control for realizing the modularization multi-level converter based on two level SVPWM modulator approaches.
Preferably, the reference voltage control module in the step 2 includes outer voltage and current inner loop, reference voltage
The course of work of control module includes the following steps:Ensure that DC bus lateral capacitance stagnation pressure is constant using outer voltage, utilizes electricity
Inner ring track reference electric current is flowed, outer voltage and current inner loop cooperatively form double -loop control;The reference voltage control module is defeated
Go out two paths of signals, be respectively used to control bridge arm three-phase half-bridge and lower bridge arm three-phase half-bridge, and energy after wherein signal negates all the way
It measures equalization control module and carries out operation, another way signal directly carries out operation with balancing energy control module.
Preferably, proportional and integral controller is respectively adopted in the outer voltage and voltage inter-loop,.
Preferably, the course of work of the balancing energy control module includes the following steps:By the modular multilevel change of current
The single module capacitance voltage desired value of device and all single module capacitance voltage average values make the difference after by proportional and integral controller, obtain
To the desired value of bridge arm circulation;Take the average value of upper and lower bridge arm current as actual rings flow valuve;By the desired value of bridge arm circulation with
By proportional and integral controller after actual rings flow valuve work difference, the output signal of balancing energy control module is obtained.
Preferably, the course of work of the capacitor voltage equalizing control module includes the following steps:By the modular multilevel change of current
After device single module capacitance voltage desired value and single module capacitance voltage actual value work difference after proportional controller, it is multiplied by ratio system
Number, you can obtain the output signal of single module capacitor voltage equalizing control module.
Preferably, the course of work of the phase-shifted SPWM modulation module includes the following steps:By modular multilevel
Compared with transverter single module reference voltage differs the high frequency triangular carrier of fixed angle with phase, drive signal is generated.
Preferably, the course of work of the 2D-SVPWM generation modules includes the following steps:By reference voltage control module
Output voltage by space vector pulse width modulation module SVPWM, generate reference voltage signal, energy be superimposed on reference voltage signal
Equalization control module output signal and capacitor voltage equalizing control module output signal are measured, single module reference voltage, and and triangle are obtained
Carrier wave compares to generate drive signal.
Preferably, in the step 4, signal, balancing energy control module are defeated all the way for new reference voltage control module output
Go out two paths of signals, the output signal of new reference voltage control module directly with balancing energy control module wherein all the way signal into
Row operation, the another way signal of balancing energy control module negate the rear output signal with new reference voltage control module and are transported
It calculates.
Beneficial effects of the present invention:
1. the SVPWM method of modularization multi-level converter is simplified to two level SVPWM modulator approaches by the present invention
With the combination of phase-shifting carrier wave modulator approach.
2. the present invention can effectively improve DC voltage utilization rate, optimize the quality of output waveform.
3. realization process of the present invention is simple, it is easy to accomplish, and it is suitable for any level, it is versatile, it can be controlled in MMC
Field is widely used and promoted.
Description of the drawings
Fig. 1 is the topological structure of the single module MMC in a kind of embodiment of the present invention;
Fig. 2 is traditional modular multilevel converter SPWM control methods;
Fig. 3 is the equivalent SVPWM control method of Modular multilevel converter that step of the present invention (1) obtains;
Fig. 4 is that the Modular multilevel converter that step of the present invention (2) obtains simplifies SVPWM control method;
Fig. 5 is the simplification SVPWM control method for the Modular multilevel converter that the present invention finally obtains.
Specific implementation mode
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to embodiments, to the present invention
It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to
Limit the present invention.
The application principle of the present invention is explained in detail below in conjunction with the accompanying drawings.
Fig. 1 is the topological structure of single module MMC in an embodiment of the present invention, V in figurepa1And Vpa2Indicate single module MMC
A phases on bridge arm power device, Vna1And Vna2Indicate the power device of a phase lower bridge arms of single module MMC;Vpb1And Vpb2It indicates
The power device of bridge arm, V in the b phases of single module MMCnb1And Vnb2Indicate the power device of the b phase lower bridge arms of single module MMC;Vpc1
And Vpc2Indicate the power device of bridge arm in the c phases of single module MMC, Vnc1And Vnc2Indicate the work(of the c phase lower bridge arms of single module MMC
Rate device.
A kind of control simplification method of the modularization multi-level converter based on two level SVPWM modulator approaches, including with
Lower step:
Step 1: the single module of modularization multi-level converter is equivalent at concatenated upper bridge arm three-phase half-bridge and lower bridge arm
Three-phase half-bridge;
As shown in phantom in Figure 1, when by the three-phase of single module MMC each single module of bridge arm capacitance positive and negative anodes distinguish phase
It connects, then constitutes a upper bridge arm three-phase half-bridge;Similarly, distinguish when by each single module capacitance positive and negative anodes of three-phase lower bridge arm
It is connected with each other, also constitutes a lower bridge arm three-phase half-bridge.Therefore, upper bridge arm three-phase half can be regarded as by single module MMC is equivalent
The series connection of bridge and lower bridge arm three-phase half-bridge.
Step 2: establishing the SVPWM Controlling model equivalent with the SPWM Controlling models of modularization multi-level converter;Such as figure
Shown in 2, SPWM Controlling models include:Reference voltage control module, balancing energy control module, 2N capacitor voltage equalizing control module
With the 2N phase-shifted SPWM modulation module for output drive signal to modularization multi-level converter, phase-shifted SPWM
Modulation includes phase-shifting carrier wave modulation module and SPWM modulation modules;As shown in figure 3, SVPWM Controlling models are by SPWM Controlling models
In phase-shifted SPWM modulation module be substituted for phase-shifting carrier wave 2D-SVPWM modulation modules, that is, use two level space vector arteries and veins
Wide modulator approach (SVPWM) replaces sinusoidal pulse width modulation method (SPWM), and phase-shifting carrier wave 2D-SVPWM modulation modules include carrier wave
Phase shift modulation module and 2D-SVPWM generation modules, N are the quantity of single module in modularization multi-level converter, the electricity of single module
Line structure is as shown in Figure 1, include upper and lower two three-phase half-bridges;
Traditional SPWM Controlling models of the modularization multi-level converter in Fig. 2 are carried out in conjunction with the single module MMC in Fig. 1
Description;U in figuredcIt is DC bus-bar voltage desired value, IRefIt is reference current value.Tradition SPWM Controlling models are broadly divided into four
A part:Reference voltage control, balancing energy control, voltage Pressure and Control and phase-shifting carrier wave modulation.Wherein, reference voltage controls
It is mainly used for controlling desired output voltage, including outer voltage module and current inner loop module, outer voltage module is for protecting
It is constant to demonstrate,prove DC bus lateral capacitance stagnation pressure, current inner loop module is used for track reference electric current, it is preferable that outer voltage module and electricity
Stream inner loop module is all made of proportional and integral controller, and the reference voltage control module exports two paths of signals, is respectively used to control
Upper bridge arm three-phase half-bridge and lower bridge arm three-phase half-bridge, and wherein signal negates rear balancing energy control module progress operation all the way,
Another way signal directly carries out operation with balancing energy control module;It is to ensure modularization that balancing energy, which controls main purpose,
The three-phase bridge arm of multilevel converter divides gross energy equally, i.e., so that each phase bridge arm direct current stagnation pressure is identical;Capacitor voltage equalizing control is main
Purpose is the energy by redistributing single module in bridge arm so that the capacitance voltage of each single module remains constant;And carrier wave moves
Mutually modulation mainly (uses 2D-SVPWM to generate mould using the modulating wave for using different modulating means to obtain in each single module
The modulating wave that block generates), the triangular carrier obtained from different phase-moving methods is compared, and the switch to generate power device drives
Dynamic signal.Further, phase-moving method above-mentioned is:When N is odd number, the phase by pi of upper and lower bridge arm modulating wave, above and below
The phase that bridge arm corresponds to single module carrier wave is identical, and the phase of adjacent single module carrier wave differs 2 π/N;When N is even number, upper and lower bridge
The phase by pi of arm modulating wave, upper and lower bridge arm correspond to phase by pi/N of single module carrier wave, the phase of adjacent single module carrier wave
Differ 2 π/N.
As shown in Figure 3, Uw1pxIndicate the modulated signal of x-th of single module of bridge arm on MMC, Uw1nxIndicate MMC lower bridge arms the
The modulated signal of x single module, 0≤x≤N., and modularization multi-level converter is connected in series by N number of single module
Step 3: in view of before capacitor voltage equalizing controlling unit, the modulating wave of upper and lower all single modules of bridge arm shares respectively
The output signal of respective balancing energy controlling unit, as shown in figure 4, the quantity of 2D-SVPWM generation modules is simplified to 2, and
Each 2D-SVPWM generation modules are moved between balancing energy control module and capacitor voltage equalizing control module, while capacitance is equal
The output signal value of pressure control module is restricted in [- 1,1] range so that the output signal of balancing energy control module is divided first
Not Jing Guo each 2D-SVPWM generation modules, 2D-SVPWM generation modules and corresponding capacitor voltage equalizing control module are defeated after operation
Go out to phase-shifted SPWM modulation module, as seen from Figure 4, Uw2pIndicate the shared control letter of all single modules of bridge arm on MMC
Number, Uw2nIndicate the shared control signals of all single modules of MMC lower bridge arms;
Step 4: in view of before balancing energy controlling unit, the modulating wave of upper and lower all single modules of bridge arm shares reference
The output signal of voltage control loop section, as shown in figure 5, the quantity of 2D-SVPWM generation modules is simplified to 1, and by 2D-
SVPWM generation modules are advanced to after former reference voltage control module, and 2D-SVPWM generation modules control mould with former reference voltage
Block is collectively formed new reference voltage control module, and in new reference voltage control module, the output of former reference voltage control module is believed
It is output to 2D-SVPWM generation modules after number negating;Simultaneously by the output of energy equalization control module and capacitor voltage equalizing control module
Signal value is restricted in [- 1,1] range, and the output of new reference voltage control module and balancing energy control module is transported by plus-minus
After calculation plus and minus calculation, final output signal to phase-shifting carrier wave are done with the output signal of corresponding capacitor voltage equalizing control module respectively
SPWM modulation modules (the final modulating wave for generating each module), by each phase-shifted SPWM modulation module by modulating wave above-mentioned
It is compared with the triangular carrier of out of phase, the switching drive signal of all power devices of final output is to modular multilevel
Transverter realizes the control of the modularization multi-level converter based on two level SVPWM modulator approaches, in Fig. 5, Uw3nIndicate MMC
The output signal of reference voltage controlling unit.The output signal of the new reference voltage control module is directly controlled with balancing energy
The wherein signal progress operation all the way of module, the another way signal of balancing energy control module negate rear and new reference voltage and control
The output signal of module carries out operation.
In an embodiment of the present invention, the course of work of the reference voltage control module includes the following steps:Electricity
Press the double -loop control of outer shroud and current inner loop, voltage inter-loop that proportional and integral controller, current inner loop is used to use proportional integration tune
Save device.
Preferably, the course of work of the balancing energy control module includes the following steps:By the modular multilevel change of current
The single module capacitance voltage desired value of device and all single module capacitance voltage average values make the difference after by proportional and integral controller, obtain
To the desired value of bridge arm circulation;Take the average value of upper and lower bridge arm current as actual rings flow valuve;By the desired value and reality of circulation
By proportional and integral controller after circulation value work difference, the output signal of balancing energy control module is obtained.
Preferably, the course of work of the capacitor voltage equalizing control module includes the following steps:By the modular multilevel change of current
After device single module capacitance voltage desired value and single module capacitance voltage actual value work difference after proportional controller, it is multiplied by ratio system
Number, you can obtain the output signal of single module capacitor voltage equalizing control module.
Preferably, the course of work of the phase-shifted SPWM modulation module includes the following steps:By modular multilevel
Compared with transverter single module reference voltage differs the high frequency triangular carrier of fixed angle with phase, drive signal is generated.
Preferably, the course of work of the 2D-SVPWM generation modules includes the following steps:By the modular multilevel change of current
The output voltage of device original reference voltage control module generates new reference voltage signal, newly by space vector pulse width modulation module
Stack power equalization control module output signal and capacitor voltage equalizing control module output signal, obtain single mode on reference voltage signal
Block reference voltage, and to generate drive signal compared with triangular carrier.
The control process of simplification algorithm of the present invention is:By modularization multi-level converter direct voltage reference value UdcWith it is defeated
Go out current reference value IRef, by reference to voltage control module, obtain reference voltage signal;After reference voltage signal is negated, lead to
2DSVPWM modules are crossed, reference voltage signal after being modulated;Stack power equilibrium control is distinguished on the modulation reference voltage signal
Module output signal and capacitor voltage equalizing control module output signal processed, can be obtained the corresponding reference voltage level of each single module;It should
Reference voltage level is respectively compared with the triangular carrier of out of phase, you can obtains the drive signal of power device.Relative to existing
For technology, the present invention is by the equivalent string for regarding upper bridge arm three-phase half-bridge and lower bridge arm three-phase half-bridge as of modularization multi-level converter
After connection, Rational Simplification Controlling model, with two level SVPWM modules instead of three level SVPWM modules, control algolithm is able into one
Step simplifies, and has popularization, application value.
The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention.The technology of the industry
Personnel are it should be appreciated that the present invention is not limited to the above embodiments, and the above embodiments and description only describe this
The principle of invention, without departing from the spirit and scope of the present invention, various changes and improvements may be made to the invention, these changes
Change and improvement all fall within the protetion scope of the claimed invention.The claimed scope of the invention by appended claims and its
Equivalent thereof.