By Topic

Energy Conversion, IEEE Transactions on

Issue 1 • Date March 2012

Filter Results

Displaying Results 1 - 25 of 25
  • Table of contents

    Page(s): C1 - C4
    Save to Project icon | Request Permissions | PDF file iconPDF (143 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Energy Conversion publication information

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (40 KB)  
    Freely Available from IEEE
  • A Space-Vector Modulation Scheme for Multilevel Open-End Winding Five-Phase Drives

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1268 KB) |  | HTML iconHTML  

    Open-end winding three-phase variable speed drives with dual-inverter supply have been extensively investigated for various applications, including series hybrid powertrains and propulsion motors. The topology is simple to realize while offering a higher number of switching states without the need for capacitor voltage balancing algorithms, when compared to the standard multilevel converters. This paper extends the open-end winding concept to a five-phase drive. A relatively simple space-vector modulation (SVM) algorithm, based on the already well-understood five-phase two-level drive SVM method, is developed. The proposed modulation technique has the advantage of being straightforward to implement and, like its two-level counterpart, is able to generate output voltages with minimum low-order harmonic content. The method generates up to 17-level output phase voltage and, therefore, offers superior harmonic performance when compared to the two-level five-phase modulation. The developed scheme is verified via detailed simulations and experiments, using a five-phase induction machine operating under open-loop V/f control. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and Analysis of a Slope Voltage Control for a DFIG Wind Power Plant

    Page(s): 11 - 20
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1310 KB) |  | HTML iconHTML  

    This paper addresses a detailed design of a wind power plant and turbine slope voltage control in the presence of communication delays for a wide short-circuit ratio range operation. The implemented voltage control scheme is based upon the secondary voltage control concept, which offers fast response to grid disturbances, despite the communication delays, i.e., this concept is based on a primary voltage control, located in the wind turbine, which follows an external voltage reference sent by a central controller, called secondary voltage control, which is controlling the voltage at the point of connection with the grid. The performance has been tested using PSCAD/EMTDC program. The plant layout used in the simulations is based on an installed wind power plant, composed of 23 doubly fed generator wind turbines. The resulting performance is evaluated using a compilation of grid code voltage control requirements. The results show that fast response to grid disturbances can be achieved using the secondary voltage control scheme, and the fulfillment of the design requirements can be extended for a wide range of short-circuit ratios. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Improved Lead–Acid Battery Pack Model for Use in Power Simulations of Electric Vehicles

    Page(s): 21 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1138 KB) |  | HTML iconHTML  

    A new model for a lead-acid battery pack is proposed for use in power simulations of electric vehicles. A linear approximation using a constant voltage drop has been used to model the charge-transfer resistance of the battery pack, and an exponential voltage-recovery equation has been used to model the transient capacitance effects following a period of discharge. The new model is easy to implement with simple calculations and easily acquired parameters, combining speed of implementation with accuracy. The new model was found to have a peak error of 3.1% in drive cycle tests, thus comparing favorably to existing models of similar complexity. An initial assessment of the model's suitability for use with a lithium-ion battery pack was also performed, finding a peak error of 5%. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of Saturation on the Airgap Induction Waveform of Five-Phase Induction Machines

    Page(s): 29 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (641 KB) |  | HTML iconHTML  

    The third harmonic of the airgap induction plays a more important role in high-phase machines than in conventional three-phase machines, because it can be used to optimize the airgap waveform and produce useful torque. The paper assesses the influence of saturation on the production of an optimized induction waveform in the airgap of five-phase induction machines through the third harmonic induction component. It is shown that teeth and core saturation have opposite effects in what concerns the production of optimized airgap induction. The paper also shows that, different from three-phase machines, a third harmonic airgap field can exist even when the five-phase machine is connected in delta or connected in star with neutral conductor. Analytical expressions to approximate the airgap induction including saturation effects are presented and the joint effect of stator current and saturation is discussed. Experimental results obtained from a prototype machine are presented and compared to theoretical values. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Detection of Demagnetization Faults in Surface-Mounted Permanent Magnet Synchronous Motors by Means of the Zero-Sequence Voltage Component

    Page(s): 42 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1035 KB) |  | HTML iconHTML  

    This paper develops and analyzes an online methodology to detect demagnetization faults in surface-mounted permanent magnet synchronous motors. The proposed methodology, which takes into account the effect of the inverter that feeds the machine, is based on monitoring the zero-sequence voltage component of the stator phase voltages. The theoretical basis of the proposed method has been established. Attributes of the method presented here include simplicity, very low computational burden, and high sensibility. Since the proposed method requires access to the neutral point of the stator windings, it is especially useful when dealing with fault tolerant systems. A simple expression of the zero-sequence voltage component is deduced, which is proposed as a fault indicator parameter. Both simulation and experimental results presented in this paper show the potential of the proposed method to provide helpful and reliable data to carry out an online diagnosis of demagnetization failures in the rotor permanent magnets. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel Electromagnetic Design for a Precision Planar Positioner Moving Over a Superimposed Concentrated-Field Magnet Matrix

    Page(s): 52 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (903 KB) |  | HTML iconHTML  

    This paper presents the electromagnetic design and force calculation of a compact multiaxis precision positioner. A six-coil single-moving-part platen moves over a superimposed concentrated-field permanent-magnet matrix. With a rectangular coil placed in the magnetic field generated by the superimposed concentrated-field magnet matrix, the force acting on the coil is calculated by volume integration based on the Lorentz force law. The distance between the long sides and that between the short sides of a rectangular coil are designed to be a half pitch and one pitch of the magnet matrix, respectively. This allows for the simplification of force generation and calculation, compact size, and light mass (0.64 kg) of the moving platen. Six coils are divided into three two-phase linear-motor armatures with 270° or 450° phase differences. The complete force-current relation for the entire platen with the six coils is derived. Experimental results are presented to verify the working principle of the positioner designed in this paper. The positioner can be employed for the stepping and scanning applications that require 3-DOF planar motions with long travel ranges in two horizontal directions and small rotational motions about the vertical axis. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Loss Distribution on Solid Pole Plates of Wound-Rotor Synchronous Motors Fed From Inverters Using Direct Torque Control

    Page(s): 63 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (590 KB) |  | HTML iconHTML  

    The use of VSD (variable speed drives) is becoming prominent in industry as it has the benefit of being more energy efficient than conventional process-control mechanisms (such as throttling). VSD usually rely on the use of inverters to produce the required frequency output, which contains time harmonics that eventually induce excess losses in the machine. These losses are the subject of analysis in this study. The results show that it is possible to influence the induced current magnitude (due to the space and time harmonics) through proper design modifications, as to reduce the consequent losses. The paper focuses specifically on DTC (direct torque control) VSD application on solid pole plate synchronous machines. One of the observed effects is that the time and space harmonics are distributed differently on the pole plates. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Active–Reactive Power Method for the Diagnosis of Rotor Faults in Three-Phase Induction Motors Operating Under Time-Varying Load Conditions

    Page(s): 71 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1069 KB) |  | HTML iconHTML  

    This paper presents a new method to diagnose rotor faults in operating three-phase induction motors under the presence of time-varying loads. The proposed diagnostic strategy relies on a combined analysis of the amplitude and phase spectra of the instantaneous active and reactive powers of the motor, and allows to discriminate the effects introduced by a rotor fault from the ones caused by an oscillating load torque, even when these phenomena occur simultaneously. A theoretical analysis carried out using a linearized model of the induction motor in a synchronous reference frame, complemented with several simulation and experimental results, confirms the validity of the proposed diagnostic approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An In Situ Efficiency Estimation Technique for Induction Machines Working With Unbalanced Supplies

    Page(s): 85 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1580 KB) |  | HTML iconHTML  

    In situ machine efficiency estimation techniques are increasing in importance due to pressures to improve performance and for demand-side management. Numerous techniques have been proposed to estimate the efficiency of an induction motor in situ . Only a few are actually practical considering the level of intrusion and the accuracy. Besides, very little has been done to make these methods compatible with the unbalanced supply condition that exists in most industrial applications. In this paper, a new evolutionary-based in situ efficiency estimation technique, capable of dealing with balanced and unbalanced power supply conditions without the requirement of the no load test, is proposed. The effectiveness of this method is verified by experimental results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Wind Speed on Wind Turbine Power Converter Reliability

    Page(s): 96 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1199 KB) |  | HTML iconHTML  

    Wind turbine power converter system (WTPCS) is a crucial device in a wind energy conversion system. This paper presents the new failure rate models and a reliability evaluation technique for the (WTPCS) considering effects of wind speeds, which can be named by the multistate probability analysis method. The case studies on the WTPCS of a 2 MW wind turbine with a permanent magnet synchronous generator are conducted using wind speed data at Lauwersoog and Valkenburg wind sites in Holland. The results indicate that reliability of the WTPCS is affected significantly by variations of wind speed and the rated wind speed of wind turbine. The effectiveness of the proposed method is demonstrated by examples. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel Method for Identifying Parameters of Induction Motors at Standstill Using ADALINE

    Page(s): 105 - 116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1388 KB) |  | HTML iconHTML  

    In this paper, we propose a new method for an online electric parameters identification of an induction motor (IM). This method is carried out in the IM standstill configuration and uses adaptive linear neuron (ADALINE) networks. In order to simplify the identification process, the IM model is approximated by two first-order subsystems: one is valid at low frequencies (LFs), called the slow system and the other is valid at high frequencies (HFs), called the fast system. By means of two ADALINE networks, the parameters of the slow system and the fast system are identified in LFs and HFs, respectively, and thus, the required IM parameters are derived. Finally, experimental results are presented in order to validate the proposed method and to check the accuracy of the obtained parameters. The originality of this paper is the building of a model representation that is suitable for implementation with ADALINE networks. This leads to a simple implementation and ease of parameters identification. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel and Comprehensive Performance Analysis of a Single-Phase Two-Winding Self-Excited Induction Generator

    Page(s): 117 - 127
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1343 KB) |  | HTML iconHTML  

    A novel and comprehensive performance analysis of a single-phase two-winding self-excited induction generator is presented for off-grid power generation. The earlier analysis carried out was found to be incomplete with no critical studies in the different modes of operation. The proposed analysis is unified, comprehensive, and accurate for performance prediction of such system. Different models for all topologies are described and solved using the MATLAB tool-fsolve. The proposed method involves only one simple command to obtain the unknown quantities. A generalized equivalent circuit is evolved for the comprehensive model so that all other possible variants would only be particular cases. The computed and experimental results have been compared. It accounts for all parameters hitherto neglected and quantifies the impact of earlier assumptions. A method to estimate capacitive reactive volt-amperes (VAR) requirements and design suitable external capacitor topology for desired performance and voltage regulation is presented to guide system designers. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Steady-State Calculation and Online Monitoring of Interturn Short Circuit of Field Windings in Synchronous Machines

    Page(s): 128 - 138
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1004 KB) |  | HTML iconHTML  

    The interturn short circuit of field windings in synchronous machines will cause the field current increasing, reactive power output decreasing as well as the aggravation of vibration. In this paper, by using the multiloop theory and analyzing the steady-state characteristics of stator and rotor fault currents, the steady-state expression of each loop current is obtained, and then differential equations in steady-state system are reduced into linear equations; according to the principal that components of the same frequency are equal, the steady-state solution of the ac and dc components of each loop current can be obtained and the steady-state calculation of the fault can be achieved rapidly. The field winding interturn short-circuit experiments have been carried out on a 12-kW synchronous machine with three pairs of poles, the results of which agree well with that of steady-state simulations. Based on the aforementioned characteristics analysis and simulation results, an online fault monitoring method in view of the unbalanced current effective value of stator branches is proposed, by which the fault characteristics can be extracted to the highest degree and short circuit with small turns in field winding can be sensitively reflected. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel Approach to Saturation Characteristics Modeling and Its Impact on Synchronous Machine Transient Stability Analysis

    Page(s): 139 - 150
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1080 KB) |  | HTML iconHTML  

    Saturation in the ferromagnetic core significantly affects the performance of electrical machines. In the performance analysis of electrical machines, an accurate representation of the saturation characteristics in the machine model is important. In this paper, a new trigonometric algorithm is proposed to represent the saturation characteristics of electrical machines based on the measured saturation characteristics data points. This model can be applied to various kinds and sizes of electrical machines. The calculated results demonstrate the effectiveness of the proposed model. This trigonometric model has been applied to a conventional synchronous machine model and extensive stability performance analysis has been carried out. This further reveals the usefulness of the proposed trigonometric saturation model and the importance of the inclusion of saturation in stability analysis. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Test Specimen Shape Considerations for the Measurement of Rotational Core Losses

    Page(s): 151 - 159
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1165 KB) |  | HTML iconHTML  

    Accurate modeling of rotational core losses in ac electrical machines is necessary; these losses occur at the roots of teeth and at the back of the slots in stator yokes of ac machines. In order to achieve a satisfactory model, the experimental measured data have to be as accurate as possible. The purpose of this paper is to propose a novel design of a magnetic circuit based on the electromagnetic Halbach array, which generates a uniform flux density inside the specimen. Particular attention is paid to the test shape to allow accurate measurements. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Induction Machine Emulator for High-Power Applications Utilizing Advanced Simulation Tools With Graphical User Interfaces

    Page(s): 160 - 172
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1912 KB) |  | HTML iconHTML  

    In this paper, a method is presented for removing the risk associated with the testing and development of novel drive system topologies, prototype electrical machines, advanced control system strategies, or a combination of the aforementioned without using any real motors/generators. The test platforms for low-power machines are relatively inexpensive and accessible; however, as power levels increase into the upper kilowatt and megawatt range, validation of prototype machines and drives becomes costly. The proposed induction machine emulator (IME) platform utilizes the power hardware-in-the-loop concept in conjunction with a high-fidelity machine model and load dynamics. The electrical machine and its load dynamics are simulated with a real-time digital simulator, which generates appropriate control commands to a power electronics-based voltage amplifier that interfaces to a variable speed drive (VSD). Specifically, the current draw is recreated by altering the phase and magnitude of a voltage amplifier connected to a VSD under test via a unique transformer-based LCL-type coupling network. Based on the proposed concept, the use of a multiwinding, tap-changing transformer establishes a truly versatile and universal test platform for a wide range of power levels. In addition, this paper presents a control strategy in the synchronously rotating reference frame in dq coordinates for the power electronic converters in IME operation. Experimental results at the 25-kVA power level validate the feasibility and highly dynamic performance of the proposed test platform. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Power Losses in Long String and Parallel-Connected Short Strings of Series-Connected Silicon-Based Photovoltaic Modules Due to Partial Shading Conditions

    Page(s): 173 - 183
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1172 KB) |  | HTML iconHTML  

    Configuration of a photovoltaic (PV) power generator has influence on the operation of the generator, especially if it is prone to partial shading. In this paper, the mismatch losses and the power losses due to failure in tracking of the global maximum power point of a long string of 18 series-connected PV modules and three short strings of six series-connected PV modules connected in parallel are investigated under different partial shading conditions by using a MATLAB Simulink simulation model. The generators with parallel-connected short strings are studied in case when they have the same operating voltage and when they operate as separate strings. The results show that long series connection of modules and parallel connections of strings via a single inverter to the electrical grid should be minimized to avoid losses in case of partial shading conditions. Under partial shading conditions, short strings operating separately have the lowest power losses. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reliability-Centered Maintenance for Wind Turbines Based on Statistical Analysis and Practical Experience

    Page(s): 184 - 195
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    The concept of reliability-centered maintenance (RCM) is applied to the two wind-turbine models Vestas V44-600 kW and V90-2MW. The executing RCM workgroup includes an owner and operator of the analyzed wind turbines, a maintenance service provider, a provider of condition-monitoring services, and wind-turbine component supplier as well as researchers at academia. Combining the results of failure statistics and assessment of expert judgement, the analysis is focused on the most critical subsystems with respect to failure frequencies and consequences: the gearbox, the generator, the electrical system, and the hydraulic system. This study provides the most relevant functional failures, reveals their causes and underlying mechanisms, and identifies remedial measures to prevent either the failure itself or critical secondary damage. This study forms the basis for the development of quantitative models for maintenance strategy selection and optimization, but may also provide a feedback of field experience for further improvement of wind-turbine design. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • New Sensorless Rotor Position Estimator of a DFIG Based on Torque Calculations—Stability Study

    Page(s): 196 - 203
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1089 KB) |  | HTML iconHTML  

    This paper presents a new sensorless method and its stability study for the estimation of the mechanical rotor position of the wound-rotor induction machine. The main purpose of this study is to implement the control of the doubly fed induction generator (DFIG). The method is based on the model reference adaptive system and uses the electromagnetic torque as the working error variable. The method does not need any information about the stator or rotor fluxes, and so, it is only indirectly dependent of the flux dynamics. As other methods proposed recently, this can also be implemented in the rotor or in the stator reference frames and with hysteresis or with proportional-integral controllers. The stability analysis gives an instability region on the rotor current dq plane described by a circle whose diameter is the no-load stator current. The method is robust to parameter variations depending only weakly on a single parameter. Simulation and experimental results show that the method is appropriate for the vector control of the DFIG although needing an additional approach to stabilize the system in the instability region. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental Investigation of Contact Resistance for Water Cooled Jacket for Electric Motors and Generators

    Page(s): 204 - 210
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1119 KB) |  | HTML iconHTML  

    The key to the successful implementation of water jacket frame cooling in high-power electric machines, such as permanent magnet, doubly fed induction, and synchronous generators, is the contact between the laminated stator core and the frame. For improved thermal design, it is important to quantify the contact thermal resistance between lamination and frame. This paper quantitatively presents the values of conventional stator lamination and frame interface resistance through experimental results. So far, no experimental investigation has been carried out to determine this resistance. The effects of several parameters, such as surface finish, shrink fit pressures, use of thermal grease, and phase change thermal interface material on thermal contact resistance, have been experimentally investigated. The obtained values of thermal contact resistance between laminations and frame can be applied for future thermal designs of electric machines to predict accurate thermal performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Introducing ieee.tv [advertisement]

    Page(s): 211
    Save to Project icon | Request Permissions | PDF file iconPDF (203 KB)  
    Freely Available from IEEE
  • IEEE Member Digital Library [advertisement]

    Page(s): 212
    Save to Project icon | Request Permissions | PDF file iconPDF (184 KB)  
    Freely Available from IEEE
  • IEEE Power Engineering Society information for authors

    Page(s): C3
    Save to Project icon | Request Permissions | PDF file iconPDF (33 KB)  
    Freely Available from IEEE

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