scholarly journals A Unified Controller for Multi-State Operation of the Bi-Directional Buck–Boost DC-DC Converter

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7921
Author(s):  
Gabriel R. Broday ◽  
Gilney Damm ◽  
William Pasillas-Lépine ◽  
Luiz A. C. Lopes
Keyword(s):  
Feedback Linearization ◽  
Power Flow ◽  
Negative Impact ◽  
Input Voltage ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Control Loops ◽  
Variable Control ◽  
Wide Range ◽  
The Right

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.

scholarly journals X-Type Step-Up Multi-Level Inverter with Reduced Component Count Based on Switched-Capacitor Concept

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1987
Author(s):  
Erfan Azimi ◽  
Aryorad Khodaparast ◽  
Mohammad Javad Rostami ◽  
Jafar Adabi ◽  
M. Ebrahim Adabi ◽  
...  
Keyword(s):  
Power Flow ◽  
Input Voltage ◽  
Switching Frequency ◽  
Switched Capacitor ◽  
Level Control ◽  
Voltage Balancing ◽  
Simulink Model ◽  
Wide Range ◽  
Multi Level ◽  
Laboratory Prototype

This paper aims to present a novel switched-capacitor multi-level inverter. The presented structure generates a staircase near sinusoidal AC voltage by using a single DC source and a few capacitors to step-up the input voltage. The nearest level control (NLC) strategy is used to control the operation of the converter. These switching states are designed in a way that they always ensure the self-voltage balancing of the capacitors. Low switching frequency, simple control, and inherent bipolar output are some of the advantages of the presented inverter. Compared to other existing topologies, the structure requires fewer circuit elements. Bi-directional power flow ability of the proposed topology, facilitates the operation of the circuit under wide range of load behaviors which makes it applicable in most industries. Besides, a 13-level laboratory prototype is implemented to realize and affirm the efficacy of the MATLAB Simulink model under different load conditions. The simulation and experimental results accredit the appropriate performance of the converter. Finally, a theoretical efficiency of 92.73% is reached.

scholarly journals Influence of Power Losses in the Inductor Core on Characteristics of Selected DC–DC Converters

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1991 ◽  
Author(s):  
Krzysztof Górecki ◽  
Kalina Detka
Keyword(s):  
Nanocrystalline Material ◽  
Input Voltage ◽  
Load Resistance ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Power Losses ◽  
Boost Converters ◽  
The Core ◽  
Operation Conditions ◽  
Wide Range

The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is used. Correctness of this model is verified experimentally for three different magnetic materials. Computations are performed with the use of this model and the Excel software for inductors including cores made of ferrite, powdered iron, and nanocrystalline material in a wide range of load resistance, as well as input voltage of both the considered converters operating at different values of switching frequency. The obtained computation results show that power losses in the inductor core and watt-hour efficiency of converters strongly depend on the material used to make this core, in addition to the input voltage and parameters of the control signal and load resistance of the considered converters. The obtained results of watt-hour efficiency of the considered direct current (DC)–DC converters show that it changes up to 30 times in the considered ranges of the mentioned factors. In turn, in the same operating conditions, values of power losses in the considered cores change from a fraction of a watt to tens of watts. The paper also considers the issue of which material should be used to construct the inductor core in order to obtain the highest value of watt-hour efficiency at selected operation conditions of the considered converters.

scholarly journals Analysis of Control Valves Stiction Quantification Tool

2017 ◽  
Vol 16 (2) ◽  
pp. 70
Author(s):  
H. Zabiri ◽  
M Gaberalla M K Elarafi
Keyword(s):  
Case Studies ◽  
Process Model ◽  
Control Valve ◽  
Operating Conditions ◽  
Optimal Conditions ◽  
Model Accuracy ◽  
Control Loops ◽  
Wide Range ◽  
Valve Stiction ◽  
The Impact

Control valve stiction is considered as one of the main sources of control loops nonlinearities which impacts plants profitability. In turn, this phenomenon hinders the plant from being operated at optimal conditions. Therefore, an efficient and accurate stiction quantification algorithm is required for accurate stiction compensation and timely scheduling of control valve maintenance. This research investigates the robustness and recommends improvements to the previously developed stiction quantification approach by Zabiri et al. The approach was tested under several operating conditions which were simulated in five case studies by using MATLAB software. The case studies investigated the impact of a wide range of stiction values, controller tuning, disturbance, time delay and noise on the quantification approach. The algorithm was found to be robust since it quantified the correct values of stiction regardless of the operating conditions. It was found that the accuracy of the quantification results depends on the process model accuracy, number of data samples and the search resolution. A number of improvements were recommended and validated by simulation in order to further enhance the current quantification approach. As conclusion, the algorithm can be applied on any type of process due to its robustness.

scholarly journals Pi Power System Controller: Eigenstructure – Based Design and Sensitivities

2021 ◽  
Vol 15 ◽  
pp. 84-89
Author(s):  
A. El kashlan ◽  
Shady El kashlan
Keyword(s):  
Power System ◽  
Operating Conditions ◽  
System Control ◽  
System Matrix ◽  
Power System Stabilizers ◽  
Power System Control ◽  
Response Characteristics ◽  
Wide Range ◽  
Parameter Variations ◽  
The Right

Significant advances in power system control design techniques that can take into consideration plants linearized around a number of operating conditions. Most of these techniques are based on eigenspectrum analysis which has numerous advantages. A wealth of applications of eigenstructure assignment are available in the literature and showed that new applications have been found and parametric solution of eigenspectrum assignment can be used successfully to design feedback controllers. The use of supplementary controller added to the automatic voltage regulator (AVR) is a practical effective way to supply additional positive damping to system oscillations via power system stabilizers. The present paper utilizes eigenspectrum analysis in the practical design of proportional integral (PI) type power system stabilizers, in order to achieve good steady state as well as transient response characteristics. Eigenspectrum analysis is attractive since it takes into account freedom in determining feedback gains and provides the frequencies and the damping at each frequency for the entire system in a single calculation. Moreover sensitivity of eigenvalues and eigenvectors with respect to parameter variations are assessed so as to provide information to improve setting parameters for power system damping and stability, without ignoring the operating conditions. The results of eigenvalue/eigenvector sensitivity are tangible for analysis with a wide range of parameter variations and is presented through the right and left eigenvectors of the system matrix and also through Taylor series analysis.

scholarly journals Social Orientation of the Prosecutor’s Supervision

2018 ◽  
Vol 5 (2) ◽  
pp. 200-204
Author(s):  
M V Kolesov
Keyword(s):  
Negative Impact ◽  
Well Being ◽  
Individual Characteristics ◽  
Social Orientation ◽  
Labor Rights ◽  
Commercial Activities ◽  
The Social ◽  
Wide Range ◽  
The Individual ◽  
The Right

The article examines one of the possible ways to optimize the activities of the prosecutor’s office in one of the most priority areas of prosecutorial activity - the protection of small and medium-sized businesses, as well as labor rights of workers, in particular, the right to timely and full payment of labor. The social importance of observance of labor rights and the orientation towards the development of small and medium-sized businesses are not subject to challenge and are emphasized by the President of the Russian Federation. The author justifies the need to introduce new approaches in the activity of the prosecutor’s office in these branches of legal relations, proposes a fundamentally new socially-oriented model for the implementation of prosecutorial supervision and the adoption of measures for prosecutorial response.The prevalence and scale of violations committed by controlling bodies in relation to small and medium-sized businesses, and the latter - with respect to their employees should be identified as one of the most important problems of modern Russia, which has an extremely negative impact on the country’s economic development and the social well-being of the population. Taking into account this vector, it is justified to make proposals on changing and improving the current legislation, which can contribute to the timely elimination of the revealed violations of the law, and also effectively carry out the preventive function. Apart from this, what is especially important, the proposed novels take into account the individual characteristics of small and medium-sized businesses, in particular their reputation as employers for a wide range of people in respect of the observance of the rights of employees in the course of their commercial activities for timely and full pay. The recommendations also help to save budget funds and improve the social and economic situation in the country.

scholarly journals Wide Input Voltage Range Operation of the Series Resonant DC-DC Converter with Bridgeless Boost Rectifier

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4220
Author(s):  
Abualkasim Bakeer ◽  
Andrii Chub ◽  
Dmitri Vinnikov ◽  
Argo Rosin
Keyword(s):  
Input Voltage ◽  
Voltage Regulation ◽  
Operating Conditions ◽  
Reverse Direction ◽  
Switching Frequency ◽  
Half Cycle ◽  
Wide Range ◽  
Series Resonant ◽  
Boost Rectifier ◽  
Abnormal Operating Conditions

The series resonant DC-DC converter (SRC) can regulate the input voltage in a wide range at a fixed switching frequency. In this work, the bridgeless rectifier, which is utilized intensively in the applications of the power factor correction, has been integrated into the SRC as a voltage step-up cell at the output-side of the SRC. It is shown that the conventional overlapping pulse-width modulation (PWM) of the two metal oxide semiconductor field-effect transistors MOSFETs in this rectification cell limits the input voltage regulation range of the converter due to excessive power losses in abnormal operating conditions. The abnormal operating conditions occur when the instantaneous voltage across the resonant capacitor is larger than the secondary voltage of the isolation transformer. This happens at high values of the DC voltage gain, i.e., low input voltages and high currents, which causes the resonant current to flow in the reverse direction in the same half-cycle through a parasitic path formed by overlapping PWM of the rectifier MOSFETs. The abnormal operation results in additional conduction loss in the converter as the MOSFETs of the bridgeless boost rectifier turn on at high current at the beginning of each half of the switching period. Accordingly, the overall efficiency of the converter significantly deteriorates. This paper proposes the hybrid PWM aiming to improve the efficiency of the SRC with a bridgeless boost rectifier in a wide input voltage regulation range. The converter swaps between the overlapping and the proposed short-pulse PWM schemes to drive the MOSFETs in the bridgeless boost rectifier. The transition between the two PWM schemes is defined according to the boundary condition that relies upon the operating point of the converter power and the input voltage. The proposed hybrid PWM scheme is analyzed and compared to the overlapping PWM at different levels of the input voltage and the load power. A 300 W prototype was studied in the laboratory to show the feasibility of the proposed hybrid PWM scheme with the closed-loop control system to switch between the two PWM schemes.

Engine Variables Affecting the SI Engine Knock

2001 ◽  
Author(s):  
Mansoor Karimifar
Keyword(s):  
Pressure Fluctuations ◽  
Careful Analysis ◽  
Operating Conditions ◽  
Design Stage ◽  
Control Loops ◽  
Numerical Result ◽  
Crank Angle ◽  
Wide Range ◽  
General Aspects ◽  
Experimental Findings

Abstract To program the automatic performance control loops of the modern cars at the design stage, numerical result of engine variables effecting knock intensity is the most important tool. Although general aspects of the effect of engine operating conditions on knock have been studied in previous investigations, precise numerical results of that, are not available. The procedures proposed in the past to provide the requirements of the models either predicting or measuring knock are complicated and the details are not presented. In the current work, on the basis of the ‘sampling frequency theorem’ and in regard to the measured frequency of the knocking-pressure fluctuations, a fast on-line data acquisition system was designed and developed. The system was used on a variable compression ratio research engine using two different fuels. Large number of the engine pressure crank angle data were recorded at different operating conditions. Knock, intensity measurement was carried out using a developed criteria obtained by a careful analysis of pressure oscillations at 0.25 degree crank angle intervals. This lead to identification of cycles having specified knock intensity over a wide range of operating conditions. Effect of engine variables on knock intensity was therefore measured numerically for both fuels. Using the simple criteria to study the effect of engine operating conditions on the intensity of knock produced the results which agreed with the earlier experimental findings.

Analysis and Comparison Between Fixed and Variable Volume Ratio Expander for Micro-Scale ORC

2015 ◽  
Author(s):  
Sergei Gusev ◽  
Martijn van den Broek
Keyword(s):  
Waste Heat ◽  
Volume Ratio ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Working Fluid ◽  
Small Scale ◽  
Variable Volume ◽  
Fixed Volume ◽  
Wide Range ◽  
The Right

Waste heat recovery has become very important in the last decennia. The Organic Rankine Cycle is the most popular technology to transform waste heat into mechanical work or electricity. While large and medium scale installations are widely available on the market for various temperature and power levels, small scale ORCs are still in a pre-commercial phase because of a relatively high specific price. To make small scale ORCs more attractive for potential customers, the price has to be drastically reduced which means reducing the manufacturing and assembling operations, the number of parts in assemblies and unification of these assemblies. In addition, the performance has to be increased by using advanced cycle architectures and the right fluids. Not only the right choice of the working fluid is important but also the expander built-in volume ratio (BVR) has to be optimal or improved. Neither a fixed volume ratio expander, nor a turbine can provide an optimal expansion of a working fluid in a wide range of operating conditions [1]. In automotive applications, for instance, a strongly fluctuating heat input will be introduced to an ORC unit. To estimate losses caused by non-optimal operation, a model of a volumetric expander has been developed and verified using the result of extensive test campaigns with a screw expander. The volume ratio of the expander mentioned cannot be physically changed, so under widely changing pressure ratio, caused by varying inlet waste heat and ambient temperatures, it operates mostly far from its design point. The model gives a possibility to vary the BVR in order to compare a fixed-volume ratio expander with a variable one. Benefits from replacement of this expander by an adaptive one are studied. Only steady states are taken into account since there is no dynamic model of this expander developed yet. As a consequence of the results obtained, a concept of a variable volume ratio expander is proposed.

scholarly journals Three-Port Series-Resonant DC/DC Converter for Automotive Charging Applications

Electronics ◽  
2021 ◽  
Vol 10 (20) ◽  
pp. 2543
Author(s):  
Jannik Schäfer ◽  
Johann Walter Kolar
Keyword(s):  
Power Density ◽  
Power Flow ◽  
Low Voltage ◽  
Circuit Complexity ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Distribution Grid ◽  
Arbitrary Power ◽  
Series Resonant ◽  
Electrical Loads

In the energy distribution grid of electric vehicles (EVs), multiple different voltage potentials need to be interconnected, to allow arbitrary power flow between the various energy sources and the different electrical loads. However, between the different potentials, galvanic isolation is absolutely necessary, either due to safety reasons and/or due to different grounding schemes. This paper presents an isolated three-port DC/DC converter topology, which, in combination with an upstream PFC rectifier, can be used as combined EV charger for interconnecting the single-phase AC mains, the high-voltage (HV) battery and the low-voltage (LV) bus in EVs. The proposed topology comprises two synergetically controlled and magnetically coupled converter parts, namely, a series-resonant converter between the PFC-sided DC-link capacitor and the HV battery, as well as a phase-shifted full-bridge circuit equivalent in the LV port, and is mainly characterized by simplicity in terms of control and circuit complexity. For this converter, a simple soft switching modulation scheme is proposed and comprehensively analyzed, in consideration of all parasitic components of a real converter implementation. Based on this analysis, the design of a 3.6kW, 500V/ 500V/ 15V prototype is discussed, striving for the highest possible power density and as low as possible manufacturing costs, by using PCB-integrated windings for all magnetic components. The hardware demonstrator achieves a measured full-load efficiency in charge mode of 96.5% for nominal operating conditions and a power density of 16.4kW/L.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

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