Search results

1 – 10 of over 9000
Click here to view access options
Article
Publication date: 6 March 2009

S.H. Fathi, M.G. Hosseini Aghdam, A. Zahedi and G.B. Gharehpetian

The purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output…

Abstract

Purpose

The purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output voltage THD.

Design/methodology/approach

In cascaded multi‐level inverters, it is usually assumed that the DC sources have the same constant voltage and output harmonics minimization is accomplished by applying proper switching angles. Employing different DC voltages with proper ratios can result in further reduction of the harmonics. After formulation of the system, i.e. describing the inverter's output voltage components in terms of the switching angles and unequal DC source voltages, a rule is applied to obtain the step heights of the staircase output waveform (DC source voltages), so that the output waveform becomes as close to the required fundamental sine wave as possible. Substituting the obtained DC source voltages into the harmonics elimination equations results in a set of equations, which are functions of switching angles only. Solving these equations leads to proper switching angles, which, regardless of the fundamental component's value, provide the specified harmonic conditions. The output voltage is then controlled by DC sources voltage regulation.

Findings

Computer simulations show that employing the proposed concept results in substantial improvement in the harmonic minimization, as well as, extending the operating range of the inverter, compared to the conventional methods with equal DC source voltage multi‐level inverters.

Originality/value

The proposed concept according to which the ratio of the DC source voltages are determined, is original.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 1 January 2006

Zbigniew Fedyczak, Leszek Frąckowiak and Maciej Jankowski

Aims to focus on steady state and transient state analysis of basic properties of new solution for a single‐phase serial AC voltage controller. Furthermore, simulation and…

Abstract

Purpose

Aims to focus on steady state and transient state analysis of basic properties of new solution for a single‐phase serial AC voltage controller. Furthermore, simulation and experimental test results of 3 kVA models are provided to confirm and verify the theoretical approach.

Design/methodology/approach

Presents a converter with auxiliary transformer and bipolar PWM AC matrix‐reactance chopper (MRC), based on Ćuk B2 topology. The MRC has the possibility of bipolar AC voltage conversion with magnitude of voltage transformation function greater than 1. The peak voltage detection method in the control circuit is applied to fast control of the load voltage changes. The steady state and transient state theoretical analysis based on averaged models of the presented controller is used. There is a four‐terminal description of the basic properties in the presented approach.

Findings

In the proposed solution only half the number of switches compared with the case of full bridge matrix chopper solution is used. The nominal load voltage can be obtained even for 50 per cent step‐down of the supply voltage.

Originality/value

Presents new topology and properties of single‐phase serial AC voltage controller.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 1 February 1937

B. Sykes

IN this article it is proposed to deal with the broad principles of operation of the various systems of control of aircraft electrical generators which are in common use…

Abstract

IN this article it is proposed to deal with the broad principles of operation of the various systems of control of aircraft electrical generators which are in common use, rather than with the detail design features and the many minor variations adopted by different manufacturers of this type of equipment.

Details

Aircraft Engineering and Aerospace Technology, vol. 9 no. 2
Type: Research Article
ISSN: 0002-2667

Click here to view access options
Article
Publication date: 9 November 2012

Uroš Flisar, Danijel Vončina and Peter Zajec

The purpose of this paper is to investigate the impact of different distribution of shoot through mode on Z‐source inverter efficiency and particularly on complexity of…

Abstract

Purpose

The purpose of this paper is to investigate the impact of different distribution of shoot through mode on Z‐source inverter efficiency and particularly on complexity of switching pattern generation. Switching pattern generation has been optimized for field‐oriented control (FOC) of induction motor operating beyond its nominal speed which can be easily accomplished due to the input voltage boosting implemented inherently by Z‐source inverter. The proposed drive is unaffected to supply voltage sags, too.

Design/methodology/approach

The space vector modulation switching pattern of the traditional FOC drive was modified in order to insert shoot through mode necessary for input voltage boosting. Since this can be accomplished only on account of zero mode of the inverter, the active modes have to be reduced. Consequently, the output voltage space vector has to be reduced, as well.

Findings

In order to maximize profit of the input DC voltage and to omit the output voltage distortion, mathematical limitations have been derived giving the optimal boost ratio for required output voltage and ride‐through capability during voltage sags.

Practical implications

The experimental tests of upgraded FOC of induction motor with the proposed distribution of shoot through mode in the switching pattern of Z‐source inverter and optimized control of inverter voltage are demonstrated. It is also shown that such a drive can withstand a long period of input voltage sags and operate in a broader field weakening regime.

Originality/value

The paper's value lies in the overall, DSP‐based control of the induction motor supplied with Z‐source inverter gaining the maximum utilization of the input DC supply source and optimum trade‐off between inverter efficiency and inverter components voltage stress.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 9 January 2007

Ghada M. Amer

The paper proposes to present the effect of the high voltage transmission lines on the metallic pipelines by calculating the induced voltage due to mutual inductance…

Downloads
6519

Abstract

Purpose

The paper proposes to present the effect of the high voltage transmission lines on the metallic pipelines by calculating the induced voltage due to mutual inductance between the two circuits especially in short circuit conditions of high voltage overhead transmission lines.

Design/methodology/approach

The electro magnetic transient program (EMTP) is used to simulate the high voltage transmission lines in normal case and in different faulty case conditions. A software is built on MATLAB program (M‐file) to study the effects of various parameters on the magnitude of the induced voltage such as: separation distance between the high voltage transmission line and the metallic pipeline (horizontal distance), different cases of short circuits and normal operation case, the screening factor, and the soil resistivity.

Findings

The three‐phase to ground fault gives the least induced voltage, and phase to ground fault case is the most serious case. The induced voltage decreases with increasing the soil resistivity until 400 Ωm and after this, the induced voltage in the metallic pipeline increases with increasing the soil resistivity for all phase fault types.

Research limitations/implications

It does not deal with all types of interference such as capacitive interference.

Practical implications

This technique helps to know the electrical influence exerted by power line on a pipeline. So it can prevent the pipeline from posing a shock hazard rather than corrosion.

Originality/value

This paper presents the effect of the high voltage transmission lines on the metallic pipelines by calculating the induced voltage due to mutual inductance between the two circuits especially in short circuit conditions of high voltage overhead transmission lines.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 1 January 2013

Javier Pereda and Juan Dixon

The aim of this paper is to improve and adapt cascaded multilevel converters for electric vehicles (EVs) to have all the advantages of these converters and to eliminate…

Abstract

Purpose

The aim of this paper is to improve and adapt cascaded multilevel converters for electric vehicles (EVs) to have all the advantages of these converters and to eliminate its limitation in the use of EVs applications. Specifically, the purpose is to use only a single power source (battery pack, fuel cell, etc.) and to generate a higher power‐quality than regular multilevel converters.

Design/methodology/approach

This paper is based in a cascaded multilevel converter conformed by two 3‐level inverters connected in series. The voltage sources of the auxiliary inverter were replaced by floating capacitors which work as active filters, reducing the power sources to one. The floating capacitor voltages were controlled by a PI controller that adjusts the modulation index (m) to obtain a zero average power in the auxiliary inverters, and a predictive control selects the optimal redundant state to reduce the error and balance all the capacitor voltages. As the modulation index is determined by the PI controller, the output voltage magnitude must be controlled by a variable voltage source (e.g. buck‐boost chopper). Additionally, the converter works with new optimal voltage asymmetries to obtain higher power quality and capacitor control stability.

Findings

The proposed converter uses a topology that conventionally generates 9‐levels of voltage, but with the proposed asymmetry is as generate 11‐levels. Also, the auxiliary power sources were eliminated.

Research limitations/implications

The proposed solution has a limited dynamic response due to the variation rate of the capacitor voltage, which is limited by the load current and the capacitance. However, the dynamic response and control stability is satisfactory for EVs applications.

Originality/value

The paper presents a new control to manage the floating capacitor voltages and uses new voltage asymmetries in cascaded multilevel converters.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 30 September 2014

Michael J. Armstrong and Christine A.H. Ross

This article is aims to inform aircraft propulsion system designers of the implications which fundamental power distribution design assumptions have on the effectiveness…

Abstract

Purpose

This article is aims to inform aircraft propulsion system designers of the implications which fundamental power distribution design assumptions have on the effectiveness and viability of turboelectric distributed propulsion (TeDP) systems. Improvements and challenges associated with selecting alternating or direct current for normal- and superconducting distribution systems are presented. Additionally, for superconducting systems, the benefits of bi-polar DC distribution are discussed, as well as the implications of operating voltage on the mass and efficiency of TeDP grid components.

Design/methodology/approach

The approach to this paper selects several high-level fundamental configuration decisions, which must be made, and it qualitatively discusses potential implications of these decisions.

Findings

Near term TeDP architectures which employ conventionally conducting systems may benefit from alternating current (AC) distribution concepts to eliminate the mass and losses associated with power conversion. Farther term TeDP concepts which employ superconducting technologies may benefit from direct current (DC) distribution to reduce the cryocooling requirements stemming from AC conduction losses. Selecting the operating voltage for superconducting concepts requires a divergence from the present day criteria employed with terrestrial superconducting transmission systems.

Practical implications

The criteria presented in the paper will assist in the early conceptual architecting of TeDP systems.

Originality/value

The governing principles behind the configuration of multi-MW airborne electrical microgrid systems are presently immature. This paper represents a unique look and the motivating principles behind fundamental electrical configuration decisions in the context of TeDP.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Click here to view access options
Article
Publication date: 12 July 2011

Galia Marinova and Dimitar Dimitrov

The paper aims to present a learning environment for optimal synthesis of voltage regulator circuits (LEOS‐VRC) using PSPICE simulator.

Abstract

Purpose

The paper aims to present a learning environment for optimal synthesis of voltage regulator circuits (LEOS‐VRC) using PSPICE simulator.

Design/methodology/approach

LEOS‐VRC supports a database with voltage regulator circuits edited as projects in PSPICE compatible format and a methodology for optimal synthesis. The methodology is based on the estimation of multiple voltage regulator circuits' realizations over a given specification, through comparative study in PSPICE, using a set of predefined specific electrical characteristics, which values are determined from simulation waveforms. LEOS‐VRC allows integrating the voltage regulator circuit in a power supply system through adding transformer, rectifier and control stages. Both linear and switch‐mode power supplies are considered.

Findings

The methodology and examples proposed illustrate the efficiency of LEOS‐VRC for teaching and self‐education in the area of power supply circuit design.

Research limitations/implications

In future LEOS‐VRC database will be enlarged with new voltage regulator circuit topologies and new controller circuits.

Practical implications

LEOS‐VRC is suitable for students in electronics and designers of power supply circuits.

Originality/value

With LEOS‐VRC students become familiar with multisolution synthesis. By analyzing the complex behaviour of the power supply system and applying comparative study and optimization criteria, they can make a motivated selection of an optimal voltage regulator design solution for a concrete application.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Click here to view access options
Article
Publication date: 2 January 2007

B.K. Kaushik, S. Sarkar, R.P. Agarwal and R.C. Joshi

To analyze the effect of voltage scaling on crosstalk.

Downloads
1339

Abstract

Purpose

To analyze the effect of voltage scaling on crosstalk.

Design/methodology/approach

Voltage scaling has been often used for reducing power dissipation of CMOS driven interconnects. An undesired effect observed due to voltage scaling is increase in propagation delay. Thus, a trade off lies between power dissipation and propagation delay with voltage scaling. However, voltage scaling can result in overall reduction of power delay product. Therefore, their lies an optimized supply voltage where‐in power dissipation and propagation delay can be optimized. Many of the previous researches have discussed about power dissipation and propagation delay only with voltage scaling. This paper for first time shows the effect on crosstalk in voltage scaled interconnects. In this paper, we primarily study the noise for an input signal having transition time of 50 ps. The simulations are run for interconnect length of 2 and 4 mm. These parameters are varied for four different cases of stimulations to aggressor and victim lines viz. VA (input at aggressor node A) and VB (input at victim node B) switching in same direction; VA is switching and VB at static low; VA and VB are switching in opposite direction; VA is switching and VB at static high.

Findings

It is quite encouraging to observe that irrespective of interconnect length and technology node used, an optimized voltage scaling reduces normalized crosstalk level.

Originality/value

Voltage scaling can be effectively used for crosstalk reduction by the new era VLSI interconnect designers. This paper shows simulation results for crosstalk reduction in different nano‐sized CMOS driven RLC‐modeled interconnects.

Details

Microelectronics International, vol. 24 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Click here to view access options
Article
Publication date: 5 July 2013

Gorazd Štumberger, Bojan Štumberger, David Stojan, Željko Plantić, Klemen Deželak, Matjaž Čemažar and Drago Dolinar

Many authors reported the decrease of performances when electric machines and electromagnetic devices were supplied by pulse width modulated (PWM) voltages. However, these…

Abstract

Purpose

Many authors reported the decrease of performances when electric machines and electromagnetic devices were supplied by pulse width modulated (PWM) voltages. However, these statements are rarely supported by measurements performed under fair conditions. The aim of this paper is to compare the performances of a single‐phase transformer and a three‐phase permanent magnet synchronous motor (PMSM) supplied by sinusoidal and PWM voltages and to find a way to evaluate the decrease of performances when PWM voltages are applied.

Design/methodology/approach

In order to perform a fair comparison between performances of the tested objects supplied by sinusoidal and PWM voltages, an experimental system was built. It contains a single‐phase and a three‐phase linear rectifier for supply with sinusoidal voltages and an H‐bridge inverter and a three‐phase inverter for supply with PWM voltages. The tests and measurements were performed on a single‐phase transformer and three‐phase PMSM, where different constant loads and different modulation frequencies were used. The test conditions were identical for the supply by sinusoidal and PWM voltages. The measured data, used for the evaluation of performances, were the input and output power and the time behaviours of currents and voltages together with their THDs.

Findings

The results presented in the paper clearly show that the efficiency of the singe‐phase transformer and three‐phase PMSM decreases with the increasing level of voltage THD. To properly determine the THD of PWM voltage, the sampling frequencies above 1 MHz and special equipment are normally required. However, if the modulation frequency is not too high, also the current THD, which can be easily determined, can be used to evaluate the decrease of efficiency in the case of supply by PWM voltages.

Originality/value

The results presented in the paper clearly show that the efficiency of the singe‐phase transformer and three‐phase PMSM decreases with the increasing level of voltage THD.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

1 – 10 of over 9000