Announcement of Approved Transactions Papers

Transactions Abstracts

his section ofIEEE Power Engineering Review serves to announcethe approval of technical papers for publication in future issues of

one of the three PES Transactions. The abstracts afford access to the es-sence and main contributions of each published paper. The abstracts arelisted by Technical Committees, which appear in alphabetic order.

To Order Technical Paper Preprints, Contact IEEE CustomerService, +1 800 678 4333 or +1 732 981 0060, fax +1 732 981 9667,e-mail customer.service@ieee.org. The IEEE member price for eachpaper Preprint is $3.50 plus delivery charges (nonmember price is$6.50 plus delivery charges). When you contact IEEE Customer Ser-vice, make sure that you identify the item you are ordering as a Preprint(not as a paper, reprint, article, etc.), and be sure to provide the Preprintorder number.

Electric Machinery

Investigation on Torsional Instability,Bifurcation, and Chaos of a Generator Set

Niu, X.; Qiu, J.

Author Affiliation: Tianjin University, Tianjin, ChinaAbstract: In this paper, nonlinear phenomenona such as Hopf bi-

furcation, chaos, and asynchronous operation of a simple power systemare explored. First, taking into account the nonlinearity of the generatorshaft and the interaction of mechanics and electrics in the generatorsets, we get a transient model by combining Park equations and me-chanics equations. Then the Hopf bifurcation, period doubling bifurca-tion, and chaos caused by too large a line resistance are investigatedwith nonlinear mode and Floquet theory. The Bifurcation figure of thesystem is also given. Further study shows that the chaos attractor breaksup into asynchronous operation when the resistance becomes larger.This method of loss of stability is different from that caused by loss ofexcitation.

Keywords: Generator sets, bifurcation, chaos, vibrations.Preprint Order Number: PE-202EC (12-2001)Discussion Deadline: May 2002

Control-Based Reduction of PulsatingTorque for PMAC Machines

Grcar, B.; Cafuta, P; Stumberger, G.; Stankovic, A.M.

Author Affiliation: Faculty of Electrical Engineering and ComputerScience, Marobor, Slovenia; Northeastern University, Boston, MA

Abstract: Control methods in torque pulsating reduction for sur-face-mounted permanent magnet motors are discussed in this paper.The pulsating torque is a consequence of the nonsinusoidal flux-den-sity distribution caused by the interaction of the rotor's permanent mag-nets with the changing stator reluctance. The proposed control methodis estimator based. To assure parameter convergence Lyapunov's directmethod is used in estimator design for the flux Fourier's coefficients. Anovel nonlinear torque controller based on flux/torque estimate is intro-duced to reduce the influence of the flux harmonics. The influence ofthe cogging torque is considerably reduced at lower motor speed usingthe internal model principle and adaptive feedforward compensationtechnique. The overall control scheme and experimental results are alsopresented.

Keywords: PMAC machines, reduction of ripple and coggingtorque, adaptive estimators, nonlinear control.

Preprint Order Number: PE-296EC (12-2001)Discussion Deadline: May 2002

An Induction Machine Model forPredicting Inverter-Machine Interaction

Sudhoff, S.D.; Aliprantis, D.C.; Kuhn, B.T.; Chapman, PL.

Author Affiliation: Purdue University, West Lafayette, INAbstract: The conventional qd induction motor model typically

used in drive simulations is very inaccurate in predicting machine per-

IEEE Power Engineering Review, March 2002

Approved Transactions PapersCall for DiscussionsDeadline: 31 May 2002

The IEEE Power Engineering Society pub-lishes discussions and closures and makesthem available for all accepted papers. Discus-sions form a most valuable adjunct to a techni-cal paper and are strongly encouraged.

Discussions must provide contributionsthrough questions and/or additional informationon the subject of the papers. Congratulatory dis-cussions are discouraged and are subject toelimination. Combined discussions of two ormore papers are not acceptable unless they referto companion papers. Discussions are limited to1,500 words (or an equivalent length if illustra-tions are used). Discussions are considered asfinal drafts that, upon acceptance by the Techni-cal Committee, are ready to be printed withoutfurther changes. Refer to the PES PublicationGuide for submission specifications. The guideis available on the Web, http://www.ieee.org/power/authkit.htm, or through the PES Execu-tive Office, FAX +1 732 562 3881, E-mail pes@ieee.org.

Submit discussions to the PES Executive Of-fice no later than 31 May 2002, for papers ab-stracted in the March 2002 issue of IEEE PowerEngineering Review. Discussions received afterthat date will be returned to the discusser andwill not be processed.

55

formance, except perhaps for the fundamental component of the cur-rent and the average torque near rated operating conditions. Predictionsof current and torque ripple are often in error by a factor of two to five.This work sets forth an induction machine model specifically designedfor use with inverter models to study machine-inverter interaction. Keyfeatures include stator and rotor leakage saturation as a function of cur-rent and magnetizing flux, distributed effects in the rotor circuits, and ahighly computationally efficient implementation. The model is consid-erably more accurate than the traditional qd model, particularly in itsability to predict switching frequency phenomena. The predictions ofthe proposed model are compared to those of the standard qd model andto experimental measurements on a 37 kW induction motor drive.

Keywords: Induction motor drives, induction motors, modeling,simulation, squirrel cage motors.

Preprint Order Number: PE-314EC (12-2001)Discussion Deadline: May 2002

Performance Enhancement of an InductionMotor by Secondary Impedance Control

Suciu, C.; Kansara, M.; Holmes, P; Szabo, W

Author Affiliation: Transilvania University of Brasov, Brasov, Ro-mania; Nottingham Trent University, U.K.

Abstract: This paper demonstrates the use of nonresistive second-ary control of an induction motor to improve efficiency, power factor,and torque. A mathematical algorithm is presented to predict the con-trol requirements in terms of secondary capacitance. The required sec-ondary capacitance is implemented by a novel electronic switchingtechnique that effectively increases the value of the used capacitor. Thisovercomes the high-capacitance demand and provides a feasible solu-tion. Experimental verification is presented in the results obtained froma small induction motor drive.

Keywords: Capacitor switching, induction motor, reactive powercontrol.

Preprint Order Number: PE-326EC (12-2001)Discussion Deadline: May 2002

Steady-State Performance of SynchronousGenerators With ac and dc StatorConnections Considering Saturation

Shanming, W; Xiangheng, W; Ylxiang, L.; Pengsheng, S.;Weiming, M.; Gaifan, Z.

Author Affiliation: Tsinghua University, Beijing, China; NavalEngineering University, Wuhan, China

Abstract: Synchronous generators with ac and dc stator connectionsare widely used in systems where simultaneous ac and dc power suppliesare needed. For these systems the voltage harmonic distortion of ac volt-age, dc voltage ripple, and dc voltage varying range are of special inter-est. Because of the commutation of rectifier and the saturation ofmagnetic circuit, the accurate calculation of voltage harmonic distortionand dc voltage varying range is comparatively difficult. This paper de-scribes a mathematical model on the basis of the multiloop method andFEM, which aims at calculating the steady-state characteristics and thevoltage waveforms of ac winding accurately. With this method, the fullsynergic effects of space harmonics resulting from the magnetic circuitgeometry, saliency, saturation, winding layouts, and slotting are in-cluded. The calculated results are compared with those ofexperiments.

Keywords: Multiloop theory, finite element method, synchronousgenerators with ac and dc stator connections, voltage harmonic distortion.

Preprint Order Number: PE-382EC (12-2001)Discussion Deadline: May 2002

Steady-State Characteristics of SynchronousMachine-Line-Commuted Converter Systems

Demiroglu, M.; Mayer, J.F.

Author Affiliation: Pennsylvania State University, PA

Abstract: A steady-state model of a synchronous ma-chine-line-commutated converter pair is obtained from a dynamic aver-age-value model of the system that accurately accounts for subtransientsaliency of the machine. This steady-state model is comprised exclu-sively of linear and nonlinear algebraic equations that relate key vari-ables of the system. Various algorithms for solving these equations togenerate characteristics that relate two or three of these variables at atime are described. Specific characteristics that are illustrated includemachine torque versus firing angle for constant dc current and dc volt-age versus dc current for constant firing angle.

Keywords: Synchronous machine, line-commutated converter,steady-state characteristics.

Preprint Order Number: PE-023EC (12-2001)Discussion Deadline: May 2002

Analytical Closed-Form Solution of a Space-VectorModulated VSI Feeding an Induction Motor Drive

Kilma, J.

Author Affiliation: Technical Faculty of CZU in Prague, CzechRepublic

Abstract: This paper presents the analysis of the time response ofthe stator and rotor currents in an induction motor fed by a space-vectorpulse-width modulated voltage source inverter. This mathematicalmodel uses the Laplace and modified Z-transform. The solution ismade in two steps: 1) finding the Laplace transform of the stator voltagespace vectors and 2) finding the inverse transform of the load currents(original function) using the modified Z-transform. The solution is notdependent on the number of the pulses of the PWM pattem. All the ana-lytical waveforms were visualized from the derived relations with theprogram MATHCAD. Experimental results prove the feasibility of theproposed mathematical model.

Keywords: Analytical solution, induction motors, inverters, PWM,space vector modulation.

Preprint Order Number: PE-604EC (12-2001)Discussion Deadline: May 2002

Simplified Steady-State Model of anSCR-Inverter-Based Load-CommutatedCommutatorless Series Motor

Mukherjee, K.; SenGupta, S.; Bhattacharya, T.K.;Chattopadhyay, A.K.

Author Affiliation: IIT Kharagpur, Kharagpur, India; B.E. Col-lege, Howrah, India

Abstract: This paper presents a simplified analytical model of a sili-con-controlled rectifier-based load-commutated inverter-drivencommutatorless series motor to predict its speed-current, torque-current,and torque-speed characteristics. The model has been formulated, keep-ing in mind the steady-state equivalent circuit of a conventional dc seriesmotor. The proposed analytical expressions relating torque and currentwith speed are found to follow an inverse law and relating torque and cur-rent is found to be parabolic, as is expected in a "series machine." Thedrive has been implemented, loaded with a dc generator, and experimen-tally similar characteristics have been obtained, as predicted by the ana-lytical model. The characteristics obtained experimentally are seen toclosely follow the ones predicted by the analytical model.

Keywords: Self-controlled synchronous motor, steady-state analy-sis, load commutated inverter, commutatorless series motor.

Preprint Order Number: PE-678EC (12-2001)Discussion Deadline: May 2002

IEEE Power Engineering Review, March 200256