By Topic

Energy Conversion, IEEE Transactions on

Issue 1 • Date March 2004

Filter Results

Displaying Results 1 - 25 of 41
  • Table of contents

    Page(s): c1 - c4
    Save to Project icon | Request Permissions | PDF file iconPDF (42 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Energy Conversion publication information

    Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (36 KB)  
    Freely Available from IEEE
  • A novel exact and universal approach for calculating the differential leakage related to harmonic waves in AC electric motors

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    In this paper, the distribution pattern of harmonic waves in AC electric motors is investigated. On the basis of this, a novel exact and universal approach for calculating differential leakage related to the harmonic waves was developed. This approach applies to any AC electric motor, regardless of winding type, single-phase or three-phase, regular or nonregular, integral-slot or fractional-slot, symmetrical or asymmetrical. Since this novel approach substitutes the approximation method adopted by conventional approaches with an exact one, it distinguishes itself by offering precise results, general applicability, and fast calculation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of the voltage distribution in a motor stator winding subjected to steep-fronted surge voltages by means of a multiconductor lossy transmission line model

    Page(s): 7 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    In this paper, the effect of steep-fronted voltage waveshapes infringing on a pulse-width-modulated (PWM) inverter fed induction motor is studied. The system, composed of a feeder cable and a stator winding, is modeled and simulated by using multiconductor transmission line theory in order to predict the voltage distribution among the coils of the stator winding. A recently developed time-domain equivalent circuit is used; it allows one to correctly describe the dielectric losses and the skin-effect in the conductors. The relationship among the voltage distribution inside the electrical insulation and parameters like the rise time of the applied voltage, the cable length, and the distributed losses is deeply discussed. Good agreement has been found among experimental and numerical results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Equivalent circuit for the performance analysis of universal motors

    Page(s): 18 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    An equivalent circuit of universal motors is developed, based on the design data. After representing the magnetomotive force distribution in the air gap, an analytical expression of the flux linkage of the armature winding coils is derived; this allows for the determination of the expressions of the speed and transformer EMFs induced in the armature winding and their representation by means of circuit parameters, as a function of the magnetic core saturation. The motor performances are computed, using the circuit parameters determined both analytically (by the design data) and by measurements. Some quantities are also compared with the ones obtained by finite-element analyses. Finally, the model is validated by experimental tests. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Short-circuit tests on a high-voltage, cable-wound hydropower generator

    Page(s): 28 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    Data from measurements on the first Powerformer generator installed in Porjus, Sweden, will be presented. The generator has a rating of 45 kV and 11 MVA. In total, the machine has been running more than 13700 h (October 2001) and has been exposed to a number of different tests including short-circuit tests on the terminal at 100% magnetization. Experience and some results from these short-circuit tests will be presented. Also, the response on the auxiliary winding during a short circuit on the main winding will be shown. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of the absolute rotor temperature of squirrel cage induction machines using measurable variables

    Page(s): 34 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    This paper presents a new method for observing the rotor temperature of high-power squirrel cage induction machines using measurable variables. The method is based on the fact that the rotor resistance depends on the actual rotor temperature. The main problem is to separate the changes in the rotor resistance due to temperature and skin effect. By comparing the input impedance with a known circle diagram measured during commissioning, it is possible to calculate changes in the rotor temperature. Further analyses also make it possible to obtain the absolute rotor temperature at any time. Results of procedure testing are demonstrated through computer simulations and evaluations of data recorded on a 75-kW test machine. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Torque ripple analysis of a PM brushless DC motor using finite element method

    Page(s): 40 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Three-phase permanent magnet brushless DC motors are widely used. As a function of the rotor position, the torque produced by these machines has a pulsating component in addition to the DC component. This pulsating torque has a fundamental frequency corresponding to six pulses per electrical revolution of the motor. The shape of the torque waveform and, thus, the frequency content of the waveform can be influenced by several factors in the motor design and construction. This paper addresses the various factors that influence the torque waveshape. It is shown that in addition to the basic induced electromotive force (EMF) waveshape, the magnetic saturation in the stator core, and the accuracy in the skewing are also key factors in determining the torque waveshape. Computer simulation using finite element technique has been conducted to study the torque waveform. Simulation results successfully duplicated the torque waveforms measured in experiments under different excitation currents. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Parameter calculation of a turbogenerator during an open-circuit transient excitation

    Page(s): 46 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    A time-domain parameter calculation of a turbogenerator state-space model is presented. The finite-element (FE) method has been used to simulate a two-dimensional (2-D) nonlinear transient condition of the turbogenerator. An open-circuit transient excitation of the machine in closed-loop conditions (excitation system and unloaded synchronous generator) was reproduced to extract flux linkages, power losses, and eddy currents produced within the generator, which allowed the computation of the parameters of an electrical circuit. An electrical circuit structure with one d-axis damper winding is proposed. New parameter behavior profiles were found for the fictitious damper winding, and the saturation effects on the field winding reactance were determined. FE commercial software is employed during the research as a validation tool. It is found that the simulated time-domain response of the lumped model closely follows the time-stepping FE model. The research was carried out for a large turbine generator of 150 MVA, 13.8 kV, 50 Hz, and two poles. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advances in online monitoring and localization of partial discharges in large rotating machines

    Page(s): 53 - 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    Some of the problems facing partial discharge (PD) measurements in rotating machines, especially during online measurements are: i) calibration of the measurements; ii) high noise levels interfering with both the measurement system and the winding under the test; as well as iii) attenuation and distortion of PD signals during transmission from the source point to the winding terminals. This paper presents a new technique and a measuring system for online PD monitoring of large rotating machines, developed by the authors. With this technique, the above mentioned problems are improved considerably. PD detection is implemented for every stator coil and the coil that PD comes from can also be identified. Inductive coils are used for decoupling of PD pulses and processing of the detected signals is in accordance with the developed technique, denoted "Intech". Remote monitoring and navigation via a telephone link is one of the system features. The system was tested on both hydro and turbo generators with good results. The detection sensitivity of the system for the conventional machines is about 1 nC under operating condition. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advanced fault diagnosis of a DC motor

    Page(s): 60 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    This paper presents a model of the DCc motor with an eccentric rotor. The winding function theory shows the effect of eccentricity fault on the motor inductances and the simulation is done using a nonsymmetric air-gap function. A modified equation is presented to show the existence of rotor slot harmonics in the DC motor current. To detect the eccentricity fault, a pattern recognition technique is utilized. The proposed algorithm works at steady state and uses armature current as input. The rotor speed is needed in order to provide the appropriate feature for the classifier. Therefore, rotor speed is estimated from the armature current using the commutation harmonics. The experimental results obtained from a 1/3-hp shunt DC motor verifies the proposed method. In order to cover different motor conditions, data are collected at different shaft speeds for both a healthy dc motor and a dc motor with an unbalanced load which exhibits static eccentricity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A permanent-magnet synchronous motor servo drive using self-constructing fuzzy neural network controller

    Page(s): 66 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    A self-constructing fuzzy neural network (SCFNN) is proposed to control the rotor position of a permanent-magnet synchronous motor (PMSM) drive to track periodic step and sinusoidal reference inputs in this study. The structure and the parameter learning phases are preformed concurrently and online in the SCFNN. The structure learning is based on the partition of input space, and the parameter learning is based on the supervised gradient descent method using a delta adaptation law. Several simulation and experimental results are provided to demonstrate the effectiveness of the proposed SCFNN control stratagem under the occurrence of parameter variations and external disturbance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Damper cages in genset alternators: FE simulation and measurement

    Page(s): 73 - 80
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    This paper describes an investigation of the function and effectiveness of the damper cage in small salient pole genset alternators. A time-stepping finite-element (FE) simulation is described and its application to the damper circuit is validated through the use of a specially manufactured rotor with wound damper coils. Further validation is provided by comparison of measured and predicted stator and main field quantities in a standard machine when subjected to sudden application of load. The simulation is then used to predict the performance of the alternator with and without the dampers for balanced and unbalanced load conditions. The effect of the damper circuit is also investigated when a nonlinear, rectifier load is applied to the machine with the modified rotor. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Voltage and frequency control of self-excited slip-ring induction generators

    Page(s): 81 - 87
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    By varying the effective rotor resistance of a self-excited slip-ring induction generator (SESRIG), the magnitude and frequency of the output voltage can be controlled over a wide speed range. A steady-state analysis based on a normalized equivalent circuit enables the control characteristics to be deduced. For a given stator load impedance, both the frequency and the voltage can be maintained constant as the speed is varied, without changing the excitation capacitance. When the stator load is variable, simultaneous voltage and frequency control requires the excitation capacitance to be changed as the rotor resistance is varied. Experiments performed on a 1.8-kW laboratory machine confirm the feasibility of the method of control. Practical implementation of a closed-loop control scheme for an SESRIG using chopper-controlled rotor resistance is also discussed. With a properly tuned proportional-plus-integral (PI) controller, satisfactory dynamic performance of the SESRIG is obtained. The proposed scheme may be used in a low-cost variable-speed wind energy system for providing good-quality electric power to remote regions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of a three-phase AC generator with inset NdFeB permanent-magnet rotor

    Page(s): 88 - 94
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB) |  | HTML iconHTML  

    This paper presents the analysis and performance of a three-phase AC generator with an inset, neodymium-iron-boron (NdFeB) permanent-magnet (PM) rotor. Such a rotor construction gives rise to an inverse saliency effect (i.e., the direct-axis synchronous reactance is less than the quadrature-axis synchronous reactance). This feature results in an improvement in the voltage regulation characteristics when the generator supplies an isolated, unity-power-factor load. By solving the equations derived from the two-axis theory, it is found that there exists, in general, two values of load current at which zero voltage regulation is obtained. The relationship between armature resistance, inverse saliency ratio, and the operating speed to give zero voltage regulation is investigated. The finite-element method (FEM) is used for computing the pertinent generator parameters for performance evaluation, namely the no-load voltage and the synchronous reactances. Flux plots are presented to confirm the origin of inverse saliency in the inset PM rotor. The theoretical analysis is validated by experiments carried out on a 2.5-kVA prototype generator. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Field-oriented vector control of synchronous motors with additional field winding

    Page(s): 95 - 101
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    This paper presents a new method to control a synchronous motor in such a way to resemble the characteristics of a DC motor. The method suggests including a second field winding to the rotor of a voltage-source-inverter-fed synchronous motor. The angular frequency of the inverter is made equal to the angular rotor speed, (of a self-controlled synchronous motor drive). The added field winding is in space quadrature to the main field winding and is properly excited in such a way as to diminish the direct axis component of the stator current at every load conditions. The motor is controlled to operate with zero power angle from the inverter side and zero direct axis current from the rotor excitation side. Therefore, it operates with minimum stator current and with unity power factor. The addition of the second field winding will not complicate the design because it is just a control winding. This winding may be made with smaller wire cross-section and a larger number of turns. The control on this winding is not complicated and it can be easily created. The synchronous motor along with the added field and the required control loops are simulated and tested extensively. The test results show excellent motor performance in motoring and regenerating modes of operation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic model for harmonic induction motor analysis determined by finite elements

    Page(s): 102 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB)  

    This paper presents a methodology for a convenient modification of induction motor equivalent circuit parameters, taking into consideration switching frequency iron losses in case of inverter supply. The method is based on the determination of harmonic iron losses in laminated iron cores under nonsinusoidal excitation by using a particular three-dimensional (3-D) finite-element model adopting a reduced scalar potential formulation. Eddy currents in iron laminations are considered by means of convenient surface current densities. Experimental verification is performed in case of a 20-kW experimental setup. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A robust hybrid current control for permanent-magnet synchronous motor drive

    Page(s): 109 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    Recently, the permanent-magnet synchronous motor (PMSM) has found widespread utilization in modern adjustable AC drives. This is achieved by using current-controlled voltage source inverter (VSI) systems. Because of its ease of implementation, fast current control response and inherent peak current-limiting capability, hysteresis current control is considered as the simplest technique used to control the motor currents for an AC machine. On the other hand, the ramp comparator controller has some advantages, such as limiting maximum inverter switching frequency to the carrier triangular waveform frequency and producing well-defined harmonics. In order to take advantage of the position features of both these two controllers, this paper presents the design and software implementation of a hybrid current controller. The proposed intelligent controller is a simultaneous combination and contribution of the hysteresis current controller and the ramp comparator. Comparisons using simulations on a 0.9-kW PMSM confirm that the proposed hybrid current controller gives better performance and has the advantage of conceptual simplicity. In particular, harmonic spectra of the stator current, obtained using a fast Fourier transform (FFT), are used for comparison purposes. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A switched reluctance machine-based starter/alternator for more electric cars

    Page(s): 116 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    Switched reluctance machines (SRMs) are considered as serious candidates for starter/alternator (S/A) systems in more electric cars. Robust performance in the presence of high temperature, safe operation, offering high efficiency, and a very long constant power region, along with a rugged structure contribute to their suitability for this high impact application. To enhance these qualities, we have developed key technologies including sensorless operation over the entire speed range and closed-loop torque and speed regulation. The present paper offers an in-depth analysis of the drive dynamics during motoring and generating modes of operation. These findings will be used to explain our control strategies in the context of the S/A application. Experimental and simulation results are also demonstrated to validate the practicality of our claims. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Symbolically aided model development for an induction machine in virtual test bed

    Page(s): 125 - 135
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1240 KB) |  | HTML iconHTML  

    A new phase-domain induction machine model for use in power system dynamic simulation is developed with the aid of a symbolic tool. The symbolic tool can automatically construct a time-domain power system component model in the resistive companion form (RCF) that is widely used in time-domain simulators. The automatic differentiation technique (ADT) is utilized within the context of a symbolic modeling language, and the tool has been implemented for the virtual test bed (VTB) simulation environment. The new induction machine model was used to study start-up transients of an induction motor. The new model was verified by comparing the simulation results to those obtained from a standard d-q model. This paper also demonstrates that a symbolically assisted technique can provide an efficient and rapid path for developing complex nonlinear device models for power system simulations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A novel excitation scheme for a stand-alone three-phase induction generator supplying single-phase loads

    Page(s): 136 - 143
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    This paper presents the operating principle and steady-state analysis of a novel excitation scheme for a stand-alone three-phase induction generator that supplies single-phase loads. The phase windings and excitation capacitances are arranged in the form of the Smith connection and the excitation scheme is referred to as the SMSEIG. In addition to providing the reactive power for self-excitation, the capacitances also act as phase balancers. With this novel excitation scheme, isolated single-phase loads can be supplied with good phase balance in the induction machine, resulting in high efficiency, large power output, and quiet machine operation. Performance analysis is based on the method of symmetrical components, from which the input impedance of the generator can be determined. Numerical solution of a simplified equivalent circuit for the machine variables, namely the excitation frequency and magnetizing reactance, enables the generator performance to be evaluated for any load and speed. With the aid of a phasor diagram, the conditions for achieving perfect phase balance are deduced and a method to compute the capacitances required is developed. Experimental investigations on a 2.2-kW induction machine confirm the feasibility of the SMSEIG. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 2-D model of the induction machine: an extension of the modified winding function approach

    Page(s): 144 - 150
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    A new method to calculate the inductances of induction machines considering axial nonuniformity is proposed. The proposed method, an extension of the modified winding function approach, allows considering nonuniformity due to skew and static and dynamic air-gap eccentricity. Theoretical fundamentals and experimental results that validate the proposed method are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Production cost analysis of dispersed generation options in a transmission-constrained load pocket of an interconnected system

    Page(s): 151 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    The present study examines and evaluates the applicability and production cost analysis of dispersed generation (DG) resources in a transmission-constrained load pocket of a two-area interconnected system with limited transfer capability. The types of DG technologies considered in the study are photovoltaics (PV), fuel cells, and microturbine units. The rationale for the study is that the electric power systems of today are experiencing a difficulty of constrained transmission lines, which have severely limited transfer capability between interconnected regions. The problem is more compounded by such factors as difficulty in obtaining rights-of-way, the strong environmental movement, public protest against the construction of additional transmission facilities, and the resulting inability to expand the constrained system. All of these factors are forcing the utility planners and third parties alike to search for other viable alternatives to meet the uncertainly growing load in their planning regions or at least to be able to compete effectively in the growing electricity market. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Flicker contribution from wind turbine installations

    Page(s): 157 - 163
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    In this paper, the flicker emission from a wind park connected to a grid with a high wind energy penetration is evaluated. The influence of wind speed, turbulence intensity, grid voltage quality, grid types, and number of turbines operating in the same group is measured and analyzed. The investigated wind turbines are of constant-speed stall-regulated type. It is found that the voltage quality of the grid to which the turbines are connected strongly influences the flicker emission of the turbines. Moreover, it is found that the formula used in IEC-61400-21 for determining the flicker contribution from a whole wind park gives too low total flicker value. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A novel real-time simulation technique of photovoltaic generation systems using RTDS

    Page(s): 164 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    For the performance test of photovoltaic (PV) generation systems, actual system apparatuses: a solar panel, converter system, and load facilities should be installed. It is also hardly possible to compare a maximum power point tracking (MPPT) control scheme with others under the same weather and load conditions in an actual PV generation system. One of the possible alternatives is to realize a transient simulation scheme for PV generation systems under real weather conditions of insolation and surface temperature of solar cell. The authors propose a novel real-time simulation method for PV generation systems under real weather conditions using a real-time digital simulator (RTDS). V--I curves of a real PV panel are tested using electric load device, and a hypothetical network of the tested PV panel is created on the RTDS by arranging electrical components from the customized component model libraries. The real weather conditions, insolation, and temperature of the PV panel, are interfaced through the analog input ports of the RTDS for real-time simulation. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation technique, and also show that cost-effective verification of availability and stability of PV generation systems is possible using the built-in simulator. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The IEEE Transactions on Energy Conversion includes in its venue the research, development, design, application, construction, installation, operation, analysis and control of electric power generating and energy storage equipment (along with conventional, cogeneration, nuclear, distributed or renewable sources, central station and grid connection). The scope also includes electromechanical energy conversion, electric machinery, devices, systems and facilities for the safe, reliable, and economic generation and utilization of electrical energy for general industrial, commercial, public, and domestic consumption of electrical energy.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Juri Jatskevich
University of British Columbia