scholarly journals Wielopoziomowe przekształtniki energoelektroniczne – topologie, zasada działania, metody modulacji

2020 ◽  
pp. 5-18
Author(s):  
Anna Czmil ◽  
Keyword(s):  
General Structure ◽  
Control Loop ◽  
Power Losses ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Modulation Technique ◽  
Modulation Methods ◽  
And Control ◽  
Hybrid Converters ◽  
Made In

In this paper selected issues concerning topological structure, operation and control as well as modulation methods used in multilevel converters are presented. There is reviewed general topologies of multilevel converters, which include Diode-Clamped Converters, Capacitor-Clamped Converters, Cascade Converters and Hybrid Converters. The general structure of a multilevel converter consisting of several stages depending on its application and topology is described. In the structure of operation, the stages of Outer Control Loop, Inner Control Loop, DC voltage stabilization and modulation are specified. Next, the division of modulation methods used in multilevel converters is presented and a detailed description of selected modulation methods is made. In the further part of the article the modulation methods were described in detail, i.e. the Level-Shifted Carrier Modulation Technique and Phase-Shifted Carrier Modulation Technique were used to present the analysis of power losses in multilevel converters.

scholarly journals Operation and Control of a Seven-Level V-Clamp Multilevel Converter

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4761
Author(s):  
Yao Xue ◽  
Xiaofeng Yang ◽  
Lutian Yuan ◽  
Trillion Q. Zheng
Keyword(s):  
Power Conversion ◽  
Modulation Method ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Output Performance ◽  
Flying Capacitors ◽  
Dynamic Voltage ◽  
Set Up ◽  
And Control ◽  
Laboratory Prototype

Multilevel converters are well suited for high-power and high-quality power conversion. This paper presents a new seven-level V-clamp multilevel converter (VMC) with reduced clamping devices. All phases of the VMC share common DC-link capacitors and realize bidirectional power conversion without flying capacitors. Each branch of the VMC sustains only a single-level voltage of the DC-link capacitors during its commutation process. Hence, the series switches can be controlled as simple as one switch and the dynamic voltage unbalancing issue is avoided. In this paper, the operation principle and the modulation method of the VMC are analyzed in detail. In addition, compensation control for non-ideal factors is designed to improve the output performance. The output fundamental distortion is compensated and the harmonics are reduced. Finally, a laboratory prototype of the seven-level VMC is set up to verify the feasibility of the presented topology and analysis.

scholarly journals Hybrid Multilevel Converters: Topologies, Evolutions and Verifications

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 615 ◽  
Author(s):  
Jianzhong Zhang ◽  
Shuai Xu ◽  
Zakiud Din ◽  
Xing Hu
Keyword(s):  
High Voltage ◽  
Control Strategies ◽  
Multilevel Converter ◽  
Power Devices ◽  
Multilevel Converters ◽  
Voltage Balancing ◽  
In Series ◽  
Good Potential ◽  
And Control ◽  
Balancing Control

Multilevel converters have good potential in high power and high voltage applications due to their advantages of reduced voltage or current stress on power devices. In recent years, hybrid multilevel converter (HMC) have attracted increasing attention since less equipment is required. In this paper, the topologies and evolutions of HMCs are presented, where five topology derivation ways are given by using basic cells in series-parallel/parallel-series. Some general topologies or structures that are used to generate higher levels are also deducted. Then many existing HMCs can be derived, and new topologies of the HMC might be inspired. The capabilities of neutral point and FC voltage balancing control are investigated. The performance of the selected FC-based HMCs is analyzed. Finally, the verifications of operation principle and control strategies for the derived HMCs are carried out.

Continuous PWM Modulation Strategy for NPC/H and H Bridge Hybrid Multilevel Converter

2013 ◽  
Vol 748 ◽  
pp. 510-513
Author(s):  
Hong Zheng ◽  
Yue Lei Shi ◽  
Hang Hui Zhang
Keyword(s):  
Control Strategy ◽  
Output Voltage ◽  
Supply Voltage ◽  
Matlab Simulation ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Voltage Variation ◽  
Slave Converter ◽  
And Control

f the ratio of NPC/H and H bridge hybrid multilevel converters DC supply voltage changed, the output voltage PWM waveform will be discontinuous. Thus an improved topology and control strategy is proposed. In new method, master converter operates at the fundamental frequency based on command voltage, slave converter adopts carrier phase shifted PWM technology (CPS-SPWM) at a higher frequency to enhance the quality of output voltage waveform. The amplitude of command voltage is higher than output voltage amplitude of the master converter at any time, to ensure that output voltage variation of both converters keeps in the same direction without any current flow backwards. Matlab simulation results demonstrate the effectiveness of the proposed control strategy and topology.

An Efficient Approach for Modeling and Control of a Quadrotor

2016 ◽  
Vol 4 (2) ◽  
pp. 1-16
Author(s):  
Ahmed S. Khusheef
Keyword(s):  
Pid Control ◽  
Control Method ◽  
Mechanical Design ◽  
Loop Control ◽  
Modeling And Control ◽  
Loop Control System ◽  
And Control ◽  
Close Loop Control ◽  
Close Loop Control System ◽  
Made In

 A quadrotor is a four-rotor aircraft capable of vertical take-off and landing, hovering, forward flight, and having great maneuverability. Its platform can be made in a small size make it convenient for indoor applications as well as for outdoor uses. In model there are four input forces that are essentially the thrust provided by each propeller attached to each motor with a fixed angle. The quadrotor is basically considered an unstable system because of the aerodynamic effects; consequently, a close-loop control system is required to achieve stability and autonomy. Such system must enable the quadrotor to reach the desired attitude as fast as possible without any steady state error. In this paper, an optimal controller is designed based on a Proportional Integral Derivative (PID) control method to obtain stability in flying the quadrotor. The dynamic model of this vehicle will be also explained by using Euler-Newton method. The mechanical design was performed along with the design of the controlling algorithm. Matlab Simulink was used to test and analyze the performance of the proposed control strategy. The experimental results on the quadrotor demonstrated the effectiveness of the methodology used.

scholarly journals Fault Simulations in a Multiterminal High Voltage DC Network with Modular Multilevel Converters Using Full-Bridge Submodules

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1653
Author(s):  
Ioan-Cătălin Damian ◽  
Mircea Eremia ◽  
Lucian Toma
Keyword(s):  
High Voltage ◽  
Energy Resource ◽  
Fault Analysis ◽  
Renewable Energy Resource ◽  
Dynamic Simulations ◽  
Multilevel Converters ◽  
Strong Focus ◽  
Modular Multilevel Converters ◽  
Overhead Power Lines ◽  
And Control

The concept of high-voltage DC transmission using a multiterminal configuration is presently a central topic of research and investment due to rekindled interest in renewable energy resource integration. Moreover, great attention is given to fault analysis, which leads to the necessity of developing proper tools that enable proficient dynamic simulations. This paper leverages models and control system design techniques and demonstrates their appropriateness for scenarios in which faults are applied. Furthermore, this paper relies on full-bridge submodule topologies in order to underline the increase in resilience that such a configuration brings to the multiterminal DC network, after an unexpected disturbance. Therefore, strong focus is given to fault response, considering that converters use a full-bridge topology and that overhead power lines connect the terminals.

Structural and Genetic Aspects of Proline-rich Proteins

1987 ◽  
Vol 66 (2) ◽  
pp. 457-461 ◽  
Author(s):  
A. Bennick
Keyword(s):  
General Structure ◽  
Single Gene ◽  
Conclusive Evidence ◽  
In Vitro Translation ◽  
Binding Studies ◽  
Nmr Studies ◽  
Post Translational Modifications ◽  
Single Precursor ◽  
Made In

Considerable advances have been made in the genetics of salivary proline-rich proteins (PRP). The genes for acidic, basic, and glycosylated PRP have been cloned. They code for precursor proteins that all have an acidic N-terminal followed by proline-rich repeat sequences. Structural studies on secreted proteins have demonstrated that not only acidic but also some basic PRPs have this general structure. It is possible that mRNA for different PRP may have originated from a single gene by differential mRNA splicing, but post-translational cleavages of the primary translation product apparently also occur. In vitro translation of salivary gland mRNA results in a single precursor protein for acidic PRP. Such in vitro translated protein can be cleaved by salivary kallikrein, giving rise to two commonly secreted acidic PRPs, and kallikrein or kallikrein-like enzymes may be responsible for other post-translational cleavages of PRPs. Acidic as well as some basic PRPs are phosphorylated. A protein kinase has been demonstrated in salivary glands which phosphorylates the PRPs and other secreted salivary proteins in a cAMP and Ca2+-calmodulinindependent manner. Knowledge of the conformation of PRPs is limited. There is no conclusive evidence of polyproline-like structure in the proline-rich part of PRPs. Ca2+ binding studies on acidic PRPs indicate that there is interaction between the Ca2+ binding N-terminal end and the proline-rich C-terminal part. This interaction is relieved by modification of arginine side-chains. 1H, 32P, and 43Ca NMR studies have further elucidated the conformation of acidic PRPs in solution. Present evidence shows that salivary PRPs constitute a unique superfamily of proteins which pose a number of interesting questions concerning gene structure, pre- and post-translational modifications, and protein conformation.

scholarly journals Diagnosis and Therapeutic Management of Liver Fibrosis by microRNA

2021 ◽  
Vol 22 (15) ◽  
pp. 8139
Author(s):  
Tomoko Tadokoro ◽  
Asahiro Morishita ◽  
Tsutomu Masaki
Keyword(s):  
Liver Fibrosis ◽  
Viral Infections ◽  
Primary Biliary Cholangitis ◽  
Medical Need ◽  
Key Factor ◽  
Complications Of Cirrhosis ◽  
And Control ◽  
Functional Rnas ◽  
Remarkable Progress ◽  
Made In

Remarkable progress has been made in the treatment and control of hepatitis B and C viral infections. However, fundamental treatments for diseases in which liver fibrosis is a key factor, such as cirrhosis, alcoholic/nonalcoholic steatohepatitis, autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis, are still under development and remain an unmet medical need. To solve this problem, it is essential to elucidate the pathogenesis of liver fibrosis in detail from a molecular and cellular perspective and to develop targeted therapeutic agents based on this information. Recently, microRNAs (miRNAs), functional RNAs of 22 nucleotides, have been shown to be involved in the pathogenesis of liver fibrosis. In addition, extracellular vesicles called “exosomes” have been attracting attention, and research is being conducted to establish noninvasive and extremely sensitive biomarkers using miRNAs in exosomes. In this review, we summarize miRNAs directly involved in liver fibrosis, miRNAs associated with diseases leading to liver fibrosis, and miRNAs related to complications of cirrhosis. We will also discuss the efficacy of each miRNA as a biomarker of liver fibrosis and pathology, and its potential application as a therapeutic agent.

Sign in / Sign up

Export Citation Format

Share Document