Development and Research of Power Electronic Converters for Adjustable Transformers

2021 ◽  
Author(s):  
◽  
Mārcis Priedītis
Keyword(s):  
Single Phase ◽  
Theoretical Calculations ◽  
Control Methods ◽  
Electronic Control ◽  
Two Phase ◽  
Semiconductor Switches ◽  
Calculation Methodology ◽  
Depth Study ◽  
Control Circuits ◽  
High Frequency Ac

The Thesis is devoted to research of for injection transformer (IT) electronic control methods for IT which are based on high-frequency AC pulse regulation in electrical circuits with the purpose to change AC electrical parameters (amplitude, rms value, phase shift) in IT control circuits. As such pulse control methods of AC systems have been rarely studied, the work pays more attention to the in-depth study of these methods, developing both calculation methods based on the basic harmonic determination of modulated AC and AC and their effect on the electrical load circuit operating parameters. In this way unipolar, bipolar and interphase modulation systems using bi-directional electronic semiconductor switches have been studied. A calculation methodology for the LC filtering system of modulated voltage signals has been developed which is based on the above-mentioned basic harmonic influence method. The transmission of such modulated regulatory influence signals through the IT system and the possibilities to provide an extended influence on the possibility of changes in IT load parameters are also considered. The paper discusses the possibilities to create new modulation-based electronic control and conversion systems for various AC applications, such as single-phase-two-phase and single-phase-three-phase voltage splitting systems. All the proposed technical solutions have been tested with computer models, and the results agree well with the theoretical calculations, which allows us to consider that the technical proposals are applicable in practice.

Effect of oxygen on the stability of 1-D Lps in Cu3Pd

1990 ◽  
Vol 48 (4) ◽  
pp. 166-167
Author(s):  
P. Huang ◽  
E. S. K. Menon ◽  
G. Ceder ◽  
D. de Fontaine
Keyword(s):  
Single Phase ◽  
Theoretical Calculations ◽  
High Resolution Electron Microscopy ◽  
Pair Interaction ◽  
Deep Minimum ◽  
Two Phase ◽  
Resolution Electron ◽  
Diffraction Patterns ◽  
The Stability ◽  
Effect Of Oxygen

The variety of ordered phases exhibited by Cu-Pd alloys has led many investigators to study it both experimentally and theoretically. Recently, we have determined the Cu-rich portion of the Cu-Pd phase diagram (Fig. 1) and indicated that the region denoted as 1-d LPS actually represents a large number of single phase fields of long period superstructures (LPS) separated by narrow two phase regions in agreement with theoretical calculations. Each single phase field would correspond to an LPS with a characteristic modulation period, which can be measured from the splitting of the 001 reflection in diffraction patterns. High resolution electron microscopy (HREM) studies on Cu-Pd alloys have revealed that the antiphase boundaries (APB) associated with the LPS formed at low temperatures exhibit a sharp character, while those in LPS equilibrated at high temperatures are diffuse. In a recent theoretical study on LPS, Ceder et al. pointed out that the pair interaction potential in reciprocal space, V(k), associated with Cu-Pd alloys shows a rather deep minimum which arises as a result of flat sections on the Fermi surface. Ordering concentration waves located away from the minimum of V(k) would quickly disappear at higher temperatures because of their higher contribution to the configuration energy, thus leading to the formation of a smooth modulation profile. Consequently, in selected area diffraction patterns (SAD), only first order satellites are expected. On the other hand, at lower temperatures, where the contribution from the ordering concentration waves away from the minimum in V(k) is also significant, higher order satellites should be observable in SAD patterns.

A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

1986 ◽  
Vol 44 ◽  
pp. 568-569
Author(s):  
G. Mackiewicz Ludtka
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Phase Field ◽  
Single Phase ◽  
Superplastic Behavior ◽  
Two Phase ◽  
Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

Measurements of single-phase and two-phase flows in a vertical pipe using ultrasonic pulse Doppler method and ultrasonic time-domain cross-correlation method

2013 ◽  
Vol 35 (3) ◽  
Author(s):  
Tat Thang Nguyen ◽  
Hiroshige Kikura ◽  
Ngoc Hai Duong ◽  
Hideki Murakawa ◽  
Nobuyoshi Tsuzuki
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Single Phase ◽  
Ultrasonic Pulse ◽  
Phase Flow ◽  
Beam Diameter ◽  
Vertical Pipe ◽  
Two Phase ◽  
Ultrasonic Time ◽  
Pulse Doppler

Ultrasonic Velocity Profile (UVP) method for measurement of single-phase and two-phase flow in a vertical pipe has recently been developed in the Laboratory for industrial and Environmental Fluid Dynamics, Institute of Mechanics, VAST. The signal processings of the UVP method include the ultrasonic pulse Doppler method (UDM)and the ultrasonic time-domain cross-correlation (UTDC) method. For two-phase flow, simultaneous measurements of both liquid and gas are enabled by using a multi-wave ultrasonic transducer (multi-wave TDX). The multi-wave TDX is able to emit and receive ultrasound of two different center frequencies of 2 MHz and 8 MHz at the same time and position. 2 MHz frequency with beam diameter 10 mm is exploited for measurement of gas. 8 MHz one with beam diameter 3 mm is used for liquid. Measurements have been carried out for laminar and turbulent single-phase flows and bubbly counter-current two-phase flows in two flow loops using two vertical pipes of 26 mm inner diameter (I.D.) and 50 mm I.D. respectively. Based on the measured results, assessment of each method is clarified. Applicability of each method for different conditions of pipe flow has been tested. Suggestions for application of the two methods have been recommended.

On the Problem of “Two-Phase” Activated Sludge

1991 ◽  
Vol 24 (7) ◽  
pp. 59-64 ◽  
Author(s):  
R. W. Szetela
Keyword(s):  
Activated Sludge ◽  
Single Phase ◽  
Phase System ◽  
Two Phase ◽  
Wastewater Treatment Process ◽  
Sludge Stabilization ◽  
Technological Advantage ◽  
In Series ◽  
State Models ◽  
Activated Sludge Systems

Steady-state models are presented to describe the wastewater treatment process in two activated sludge systems. One of these makes use of a single complete-mix reactor; the other one involves two complete-mix reactors arranged in series. The in-series system is equivalent to what is known as the “two-phase” activated sludge, a concept which is now being launched throughout Poland in conjunction with the PROMLECZ technology under implementation. Analysis of the mathematical models has revealed the following: (1) treatment efficiency, excess sludge production, energy consumption, and the degree of sludge stabilization are identical in the two systems; (2) there exists a technological equivalence of “two-phase” sludge with “single-phase” sludge; (3) the “two-phase” system has no technological advantage over the “single-phase” system.

A Novel Two-phase Soft Starter Used for Three-phase Asynchronous Motors

2020 ◽  
Vol 13 (8) ◽  
pp. 1175-1182
Author(s):  
Jingwen Chen ◽  
Hongshe Dang
Keyword(s):  
Pulse Generation ◽  
Power Module ◽  
Two Phase ◽  
Power Semiconductor ◽  
Starting Current ◽  
Semiconductor Switches ◽  
Soft Starter ◽  
Three Phase ◽  
And Control ◽  
Driving Circuit

Background: Traditional thyristor-based three-phase soft starters of induction motor often suffer from high starting current and heavy harmonics. Moreover, both the trigger pulse generation and driving circuit design are usually complicated. Methods: To address these issues, we propose a novel soft starter structure using fully controlled IGBTs in this paper. Compared to approaches of traditional design, this structure only uses twophase as the input, and each phase is controlled by a power module that is composed of one IGBT and four diodes. Results: Consequently, both driving circuit and control design are greatly simplified due to the requirement of fewer controlled power semiconductor switches, which leads to the reduction of the total cost. Conclusion: Both Matlab/Simulink simulation results and experimental results on a prototype demonstrate that the proposed soft starter can achieve better performances than traditional thyristorbased soft starters for Starting Current (RMS) and harmonics.

scholarly journals Comparative Study of Classical and MPC Control for Single-Phase MMC Based on V-HIL Simulations

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3230
Author(s):  
Milovan Majstorovic ◽  
Marco Rivera ◽  
Leposava Ristic ◽  
Patrick Wheeler
Keyword(s):  
Single Phase ◽  
Current Control ◽  
Superior Performance ◽  
Control Methods ◽  
Reference Tracking ◽  
Voltage Balancing ◽  
Current Reference ◽  
Circulating Current ◽  
Ac Current ◽  
Classical Control

The operation of single-phase Modular Multilevel Converter (MMC) is analyzed in the paper. A mathematical model of the converter is developed and described, based on which the structure and selection of parameters for Classical Control and Optimal Switching State Model Predictive Control (OSS-MPC) are defined. Additionally, the procedure for the determination of circuit parameters, such as submodule capacitance and arm inductance, is described and carried out. The listed control methods are designed and evaluated in Virtual Hardware-in-the-Loop together with single-phase MMC power circuit, regarding three control objectives: AC current control, voltage balancing control and circulating current control. Control methods are evaluated for both steady-state and transient performance and compared based on nine criteria: AC current reference tracking, THD of AC current and voltage, submodule capacitor voltage balancing, total submodule voltage control, circulating current magnitude and THD, number of control parameters and computational complexity. This is the first time that a fair comparison between Classical Control and MPC is considered in literature, resulting in superior performance of both control methods regarding four different criteria and the same performance regarding AC current reference tracking.

Analysis of Single- and Two-Phase Flows in Turbopump Inducers

1967 ◽  
Vol 89 (4) ◽  
pp. 577-586 ◽  
Author(s):  
P. Cooper
Keyword(s):  
Equation Of State ◽  
Flow Field ◽  
Thermal Effects ◽  
Single Phase ◽  
Fluid Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Recent Theory ◽  
Two Phase ◽  
Overall Efficiency

A model is developed for analytically determining pump inducer performance in both the single-phase and cavitating flow regimes. An equation of state for vaporizing flow is used in an approximate, three-dimensional analysis of the flow field. The method accounts for losses and yields internal distributions of fluid pressure, velocity, and density together with the resulting overall efficiency and pressure rise. The results of calculated performance of two sample inducers are presented. Comparison with recent theory for fluid thermal effects on suction head requirements is made with the aid of a resulting dimensionless vaporization parameter.

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