Phase Shift Angle Research Articles

Developing of functioning algorithm ofinformation-control system for phase-shifting devices in power lines

The article is devoted todevelopment of afunctioning algorithm of the control systemof phase-shifting devices in double-circuit overhead power lines, as well as to the formulation of the main tasks of this system. Based on these, functional schemes for controllingphase-shifting devices were developed.The developed system will allow, through the use of phase-shifting transformers, which belong to the flexible alternating currenttransmission system (FACTS)technology, to change the value of phase shift angle of the voltage and current vectors of one circuit relative to anotherthat.Thiswill lead to a change in the value of the wave impedance of double-circuit lines, due to the emergence of new electromagnetic connections between the conductors of the two circuits. The main task of the developed system is to support the operation of power lines in the matched load mode, when the value of the wave imped-anceis equal to the value of the load impedance. It follows from the analysis that this mode provides the lowest losses in the trans-mission of electricity through power lines.The implementation of this control system is planned by using the Internet of Things in-formation technology, that is, the formation of a wireless connection between the main elements of the system for data transmission.The developed system can be attributed to information systems, as well as the current concept of SmartGrid.Thus, a method has been proposed to increase efficiency by reducing losses during the transmission of electricity through double-circuit power lines through the use of the concept of Smart Grid.

Single-Stage Isolated and Bidirectional Three-Phase Series-Resonant AC–DC Converter: Modulation for Active and Reactive Power Control

Single-stage isolated and bidirectional (SSIB) AC–DC converters have a high potential for future solid-state transformers and smart battery chargers due to their reduced volume and high efficiency. However, there is a research gap for SSIB reactive power injection. This article introduces an SSIB three-phase AC–DC converter composed of three low frequency rectifiers linked by tiny film capacitors with a quad-active-bridge series-resonant (QABSR) DC–DC. A novel QAB modulation is proposed to solve three issues: (1) Three DC inputs with high ripple compensation, (2) active–reactive power injection, and (3) minimization of high-frequency (HF) transformers currents. The rectified grid voltages were modulated by time-variant duty ratio (DR) angles. In contrast, the DC source was modulated by a fixed DR (FDR) angle along with a phase-shift angle which changes according to the grid current amplitude. A constant HF current amplitude with minimum value was obtained. It is shown that the HF current amplitude is increased for reactive power injection. Hence, the FDR angle was used to compensate for this increase. Active and reactive power control were validated in a 2 kW prototype. Compared with other structures, tiny DC-link capacitors and smaller L filters were used. Moreover, higher efficiency (96%) and smaller grid currents THDi (3%) were obtained.

Research on the Influence of Moisture Exchange between Oil and Cellulose on the Electrical Parameters of the Insulating Oil in Power Transformers

The article presents an oil moistening method, identical to the oil moistening in power transformers. Moistening took place through the migration of moisture from the moistened pressboard to the brand new oil. The AC electrical parameters (admittance, phase shift angle, permittivity, loss tangent and conductivity) of the brand new and moistened insulating oil were tested. All measured parameters were found to be affected by the oil moistening. The greatest changes were observed in the loss tangent and conductivity. Moisturization increases the value of tanδ at a frequency of 10−4 Hz from about 20 to about 70. With an increase in frequency to about 400–1000 Hz, a minimum is observed, the position of which depends on the temperature. Its value for moistened oil is about six times lower than for brand new oil. This moisturizing increased the activation energy of the conductivity from 0.466 ± 0.0265 eV to 0.890 ± 0.0115 eV. This is likely due to the acceleration of water molecules diffusion from the pressboard into the oil with increasing temperatures. The observed changes in the oil parameters caused by moistening should be taken into account while analyzing the power transformers insulation condition using the FDS method.

Current stress minimization for isolated dual active bridge DC–DC converter

This paper presents a new phase-shift modulation for isolated dual active bridge (DAB) direct current–direct current (DC–DC) converter. The proposed technique aims to minimize the maximum current stress of the converter, which could directly increase the efficiency and reduce the device losses. This modulation technique controls the converter power through only two phase-shift angles or two degrees of freedom; one phase shift is used between the legs of its first bridge and the other one between the legs of the second bridge. Although the traditional single-phase shift (SPS) technique has only one degree of freedom, it suffers from many drawbacks in terms of high current stress and reverse circulating power flow, which decrease the converter efficiency. On the other hand, increasing the number of phase-shift angles can enhance the system performance but also increase the control complexity. Thus, a comparative analysis between the proposed modulation technique and the traditional SPS was conducted; the new method showed better performance in terms of current stress reduction, along with implementation simplicity.

Effect of the Concentration, pH, and Ca2+ Ions on the Rheological Properties of Concentrate Proteins from Quinoa, Lentil, and Black Bean.

Given consumer trends propelling a movement toward using plant protein in the food industry and searching for alternative protein ingredients by the industry, this study aimed to assess the influence of factors such as protein concentration, medium pH, and the presence of a divalent ion (Ca2+) upon the rheological properties such as viscosity change and gel formation of dispersion proteins extracted from quinoa, black beans, and lentils. A solution of each protein was prepared by varying its concentration (2.5%, 5.0%, and 10%), the pH (5.0, 7.0, and 9.0), and the incorporation of calcium chloride (0.0% and 1.0%). Each obtained solution was subjected to rheological tests to determine the parameters: consistency index (K), flow behavior (n), the storage (G’) and loss (G’’) modules, and the phase shift angle (δ). The results demonstrate that the incorporation of Ca2+, the shift in protein levels, and the decrease in pH modified the rheological behaviors of proteins, which were also influenced by the structural characteristics of each protein studied. However, thermal treatment and protein concentrations caused the most significant impact on proteins’ rheological behavior, forming gels independently of other conditions. It was possible to study and interpret the studied proteins’ rheological variations according to the environment’s conditions.

Influence of Annealing on the Dielectric Properties of Zn-SiO2/Si Nanocomposites Obtained in "Hot" Implantation Conditions.

This paper presents the results of AC electrical measurements of Zn-SiO2/Si nanocomposites obtained by ion implantation. Implantation of Zn ions was carried out into thermally oxidized p-type silicon substrates with energy of 150 keV and fluence of 7.5 × 1016 ion·cm−2 at a temperature of 773 K, and is thus called implantation in “hot” conditions. The samples were annealed in ambient air for 60 min at 973 K. Electrical measurements of Zn-SiO2/Si nanocomposites were carried out before and after annealing. Measurements were performed in the temperature range from 20 K to 375 K. The measurement parameters were the resistance Rp, the capacitance Cp, the phase shift angle θ and the tangent of loss angle tanδ, as a function of the frequency in the range from 50 Hz to 5 MHz. Based on the characteristics σ(f) and the Jonscher power law before and after sample annealing, the values of the exponent s were calculated depending on the measurement temperature. Based on this, the conductivity models were matched. Additionally, the real and imaginary parts of the dielectric permittivity were determined, and on their basis, the polarization mechanisms in the tested material were also determined.

An Improved Control Scheme for Reducing Circulating Current and Reverse Power of Bidirectional Phase-Shifted Full-Bridge Converter

Phase-shifted full-bridge (PSFB) converter is widely adopted in electric vehicle and energy storage applications. However, it suffers from serval technical drawbacks such as voltage overshoot, hard switching, severe circulating current, and large reverse power. To address such issues, an improved control scheme is proposed to enhance the performances of bidirectional operation in the PSFB converter. In this method, the precharge stage and the co-charge stage are added by adjusting the phase shift angle and duty ratio. The reverse power, circulating current and transformer Root Mean Square (RMS) Current can be reduced with the co-charge stage. Due to the precharge stage, this method can constrict voltage overshoot, while achieving zero current switching (ZCS) on the large current side devices and zero voltage switching (ZVS) on the high voltage side devices nearly along all the load range. The proposed method is described, analyzed, and validated in a 1 kW prototype which presents 96.1% peak efficiency and improves average efficiency by about 2% in the experimental results.

Microwave photonic multiform microwave frequency shift keying signal generator.

A photonic approach to realizing multiform microwave frequency shift keying (FSK) signal generation is proposed and demonstrated. In the scheme, a commercial dual-polarization quadrature phase shift keying modulator (DP-QPSKM) is employed to generate two orthogonally-polarized signals containing specific optical sidebands, and a subsequent Sagnac loop structure govern the interference results of these two signals. From a theoretical analysis, when the modulators are properly biased, microwave FSK signal with fixed double relationship or flexibly tunable subcarrier frequencies can be obtained, and high frequency multiplication can be realized in the meantime. Furthermore, a photonic-optimized coherent demodulation structure is designed to recover the binary coding data, which can effectively avoid the electronic bottleneck. Simulation has been performed to investigate the mechanism and the discussions about the robustness to non-ideal parameters including DC bias, phase shift and polarization angle are also given. In the proof-of-concept experiment, microwave FSK signal with subcarrier frequencies of 2/4, 2.2/3.8, 2.4/3.6, 2.6/3.4, 2.8/3.2 GHz are generated, and the correct binary coding data is successfully recovered with the aid of simulation platform. The simulation and experimental results can verify the feasibility of the proposed multiform microwave FSK signal generator, which may find applications in modern radar and communication systems.

Using conditional averaging of delayed signals to measure phase shift angle

Using conditional averaging of delayed signals to measure phase shift angle

A current sensor fault diagnosis method based on phase angle shift technique applying to induction motor drive

<div id="eJOY__extension_root" class="eJOY__extension_root_class" style="all: unset;">An improved method using the phase angle shift characteristic of the sine wave is proposed to diagnose the fault states of the current sensors in an induction motor drive. The induction motor drive (IMD) system applied in this study uses the field-oriented control (FOC) loop with integrated two current sensors and a speed encoder to control the rotor speed. The space vectors created from the phase angle shift technique are compared to the estimated current for the fault diagnosis algorithm. Various types of current sensor failures are investigated by MATLAB/Simulink software to check the effectiveness of the proposed method. The simulation results have proved the performance of the proposed method in enhancing the reliability and stability of the IMD system.</div>

High-Frequency Current Predictive Control Method for Multiactive-Bridge Converter

The multiactive-bridge (MAB) structure has obvious efficiency and cost advantages in multiport power electric transformer, but it brings the characteristics of strong current coupling of each transformer. To improve the dynamic response speed of MAB and reduce the coupling characteristics, a high-frequency current predictive control (CPC) method for MAB is proposed in this letter. The controller uses the enhanced single-phase shift modulation method to adjust the phase shift angle and duty cycle of four ports at the same time so that the high-frequency current can be adjusted in several switching cycles. In the proposed CPC method, the influence of control delay is analyzed and compensated, and the dc offset, which may occur in the dynamic process is analyzed and gives corresponding solutions. More importantly, the proposed CPC method can be extended to the power predictive control method to realize power decoupling of multiple ports of MAB. The parameter robustness of current and power predictive control is analyzed briefly in this letter. The proposed control method is validated on a hardware-in-loop simulation platform based on RT-lab. Experiment results show the superior dynamic performance and good robustness of the proposed method.

A High-Efficiency and High-Power-Density Interleaved Integrated Buck-Boost-LLC Converter and Its Comprehensive Optimal Design Method

Integrated buck-boost- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> (IBBL) dcconverter is a good solution for high efficiency and high power density applications. However, the bridge leg integration causes asymmetrical zero-voltage-switching process and asymmetrical secondary current. The method of high quality factor or symmetric phase shift modulation proposed in the existing research can improve the asymmetrical current issue under heavy load, but is ineffective for light load conditions. This article proposes a novel Interleaved IBBL converter to improve the asymmetry issue for whole load range. Interleaving makes the secondary current be symmetric naturally. In addition, a comprehensive optimal design method for phase-shift angle and choke inductor is proposed to minimize the total power loss of all primary elements. A 600 W/1 MHz prototype verifies that the proposed IIBBL converter achieves symmetric secondary current in whole load range, and it achieves 95.7% efficiency and 180 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> under the proposed comprehensive optimal design method.

Design of hybrid SiC/Si based T‐type three‐level LLC$ LLC$ resonant converter with wide‐input range and low conduction loss for automotive auxiliary power module

The auxiliary power module (APM) in the electrical vehicle converts the high voltage of battery pack to the low voltage to supply the electric power for the internal loads, including electric power steering, electric turbo, headed windshield and cooling pumps. The increasing demands on charging time and mileage have made the battery packs with even higher voltage (e.g. 800 V) a promising option. However, it brings a new challenge for the APM, and either the 1.2-kV silicon carbide (SiC) device or the three-level (TL) topology are used conventionally. This work proposes a cost-effective hybrid SiC/Si-based T-type TL L L C $ LLC$ resonant converter for the vehicular APM application with a high step-down ratio. The 1.2-kV SiC and 650-V Si devices are used as the main and auxiliary switches, respectively. It fully utilizes the voltage rating of device, and also improves the efficiency compared with conventional TL topology. To improve the gain range and electromagnetic interference performance, a variable frequency and adjustable phase-shift modulation scheme is adopted. At the same time, the steady-state time-domain model is established to elaborate the operation principles, topology features, and boundary conditions for soft-switching. Furthermore, the precise solutions for switching frequency and phase-shift angle are figured out. Finally, the effectiveness of model is verified by the simulation as well as the experiment. A 1-kW prototype for the application in the APM is demonstrated with the input voltage of 640–840 V and a constant output of 48 V/ 21 A.

Comprehensive Analysis of Asymmetric Modulated Dual-Active-Bridge Converter and Its Hybrid Control Strategy

Dual active bridge (DAB) converter has been widely used in distributed power supply, new energy vehicles, energy storage systems, etc. Their modulation strategy is an important research direction. At present, the research on modulation strategy is basically symmetric phase shift, but it is not enough to generalize modulation strategy comprehensively. In this article, an asymmetric phase-shifting (APS) strategy is proposed to control the power flow by simultaneously adjusting the asymmetric duty cycle and the phase-shifting angle. With this modulation scheme, the current stress and cyclic power loss can be reduced by adjusting the modulation ratio of the inductor current waveform. As a result, the light-load efficiency can be improved compared with the conventional symmetric modulation scheme. The power characteristic, current stress, soft switching characteristic, and backflow power of this modulation strategy are analyzed and calculated comprehensively. Then, based on this asymmetric strategy, a hybrid modulation strategy that can achieve ZVS over the entire power range with low current stress, low return power, and minimum rms current at light load is proposed. Finally, a 100–50 V/300 W prototype is built to verify the analysis.

Structural optimization design of sinusoidal wavy plate fin heat sink with crosscut by Bayesian optimization

• Develop an intelligent optimization scheme based on Bayesian Optimization algorithm. • Optimum design is performed by integrating the structure modeling, meshing, and evaluation. • Bayesian Optimization algorithm demonstrates a great advantage over evolutionary algorithms in efficiency. • The comprehensive thermal performance factor of the heat sink with the optimal structure increases by 17.6%. • The enhancement is explained by the reduction of the synergy angle between the velocity and the pressure gradient. The optimal structure of a sinusoidal wavy plate fin heat sink with crosscut (SWHS-WC) is determined by an efficient intelligent optimization method based on Bayesian Optimization (BO) algorithm. The comprehensive thermal performance factor (TPF) is the objective function, which is associated with the heat transfer and the pressure drop. The parametric modeling, meshing, and numerical calculation are integrated to optimize three structural parameters, including the fin amplitude, period, and phase shift angle of the heat sink, in an iterative and automated way. The result shows that the TPF of the SWHS-WC with the optimized structure is increased by 17.6%, due to the significant reduction in the pressure drop penalty, and the corresponding synergy angle between the pressure gradient and the velocity decreases by about 6.2°. Compared to the evolutionary algorithms, the BO algorithm demonstrates a great advantage in calculation efficiency, which can be used to find the global optimum design at a much smaller computational cost.

Improved ZVS Range for Three-Phase Dual-Active-Bridge Converter With Wye-Extended-Delta Transformer

The three-phase dual-active-bridge (3p-DAB) is a popular topology suitable for high-power dc–dc isolated conversion. This converter features bidirectional power flow, zero-voltage switching capability, and reduced transformer and filter volume. These features meet the requirements of several applications, such as solid-state transformers. However, when operating under light load, the resulting converter efficiency is highly degraded by the loss of soft-switching capability. This article introduces the use of a Wye-extended-Delta (Y- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta$</tex-math></inline-formula> e) transformer winding in the 3p-DAB converter, which increases the efficiency under light load, keeping the simplicity of phase-shift control. The framework developed allows a complete analysis of the converter, including the determination of the power and rms current, zero-voltage switching boundaries, and the impact of the selected phase-shifting angle in the transformer design. Additionally, this article presents a negative-sequence modulation scheme, allowing maximum efficiency under light loads to be achieved for both direct and reverse power flows. The performance of the 3p-DAB with Y- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta$</tex-math></inline-formula> e transformers is compared with previously reported winding options for the 3p-DAB. The experimental results show a converter efficiency increase, up to 10% for direct power flow and up to 9% for reverse power flow, when operating at light load (10% of nominal power).

A Bidirectional DHC-LT Resonant DC-DC Converter with Research on Improved Fundamental Harmonic Analysis Considering Phase Angle of Load Impedance

This paper presents a novel 400 V–50 V bidirectional DHC-LT resonant DC-DC converter. By adding a resonant capacitor and an auxiliary transformer based on LLC, zero-voltage switching (ZVS) and zero-current switching (ZCS) are achieved, while the output voltage gain range is broadened in two directions. Operation principles and robustness are discussed with equations. Then, the error factor of fundamental harmonic analysis (FHA) in resonant converters is analyzed. Considering the phase difference between the output voltage and resonant tank current, an improved method is proposed to describe the behavior of the DHC-LT converter more precisely. A comparison is conducted to prove the effectiveness of the proposed FHA. Furthermore, in order to reduce the output voltage and provide a ripple-free charging current, a fixed-frequency phase-shift strategy is introduced in the DHC-LT converter. ZVS can be realized through the reasonable design of dead time and phase-shift angle. Finally, a 2.5 kW prototype of the DHC-LT resonant DC-DC converter with a digital signal processor (DSP) platform and a battery/PV DC test system is established in the lab to validate the theoretical analysis.

Effect of the Phase-Shift Angle on the vertical axis Savonius wind turbine performance as a renewable-energy harvesting instrument

Wind energy is the third-largest renewable energy source after hydro and solar energy, so it has great potential in increasing renewable energy as a percentage of national energy. However, wind energy installation is only at 0.25% of the existing potential; so, it still needs to be developed. One of the development efforts is to optimize the wind turbine rotor design. Savonius rotors are among the most popular rotors to convert wind energy into electrical energy. The Savonius turbine is a simple structure, easy to modify to upgrade Savonius performance, and can be operated at low velocity. Phase-shift angles of 0°, 30°, 60°, and 90° were utilized in this study on a two-stage Savonius wind turbine. This study was carried out using Solver CFX utilizing the Computational Fluid Dynamic technique on the ANSYS Student version software. An SST (shear stress transport) turbulence model with steady-state turbulence was used. The purpose of this study was to assess the influence of PSA on the performance of the Savonius two-stage turbine. Factorial design analysis was used in conjunction with the CFD approach. The results indicated that PSA influenced the Savonius turbine’s performance, with 30° being the optimal PSA. Simultaneously, the Cpmax may be obtained using 0.29. The factorial design study with two components revealed that the Phase-Shift Angle had a considerable effect on rotor performance, and the two factors (TSR and PSA) had an interaction.

A Novel Topology for Solar PV Inverter Based on an LLC Resonant Converter With Optimal Frequency and Phase-Shift Control

In this article, a new topology for a grid-connected solar photovoltaic inverter for the direct connection to the medium-voltage grid is proposed. This topology employs an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter with a high-frequency (HF) isolation transformer in the dc–dc stage. The output of the dc–dc stage is a rectified sine wave voltage and current at the line frequency. An unfolder inverter interfaces between this dc stage and the grid. A combined phase-shift and frequency control method is used to control the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter. The phase-shift angle and switching frequency values of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter are regulated to track the reference current signal for the whole operation range. The Lagrange multiplier method is applied to find the optimal trajectory to calculate the optimal phase-shift angle and switching frequency pairs for any operation condition by considering power converter and HF transformer losses to achieve the highest efficiency at a varying current. The transformer leakage and magnetization inductances are properly designed to provide a zero-voltage switching (ZVS) for a wide operation area, and additional resonant inductor requirement is removed. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter operates in a ZVS region except in a narrow band around the zero-current crossings of the inverter output. Using an HF transformer in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter, a bulky line frequency transformer requirement is eliminated, and thus, a more compact and efficient design is obtained. The proposed topology is validated by the simulation and experimental results.

Impedance spectroscopy of polymer-ceramic composites

Polymer-ceramic composites from a new class of construction and functional materials of great potential applications in having combined hardness and stiffness of ceramics along with flexibility, elasticity, low density, and higher breakdown strength of polymers and hence are being increasingly harnessed for their specific dielectric, ferroelectric, piezoelectric, piezoelectric, electro-optic, as well as superconducting properties in micro-devices. The charge transport mechanism in polymer-ceramic composites is a longstanding problem. Alternating Current Impedance Spectroscopy (ACIS) is faind to be a valuable experimental tool for the understanding of the phenomenon of the charge transport in micro-and nano composites. Keywords: polymer composite; impedance spectroscopy; polymer; complex resistance; electric field; relaxation time; phase shift angle.