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|Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 949.|
A new zero-voltage-transition (ZVT) PWM converter for switched reluctance motor (SRM) drives is proposed in this study. By adding a ZVT-chopping switch in the front-end, all switches in the machine side converter can be operated without any chopping to regulate phase current. This allows the use of low-cost and slow-switching devices for the machine side converter. The ZVT circuitry allows high frequency operation of the chopping switch, which enhances the system dynamics and phase-current ripples. High efficiency of the integrated converter is obtained due to low switching losses.
 G. Roy, G.-E. April, and E. R. Ribeiro, "Ac-ac converter made of two semi direct frequency changers has no limits on the voltage gain," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 918.
Despite many attempts over the past ten years, the voltage gain of a Direct Frequency Changer (DFC) remains limited to 0.87. However, the recent introduction of a new converter topology, inspired from the DFC and called Semi Direct Frequency Changer (SDFC), opens the way toward an ac-ac conversion without any limitation on the voltage gain. Two SDFCs, made of six unidirectional switches, can form a full 3 phase-3 phase converter; the SDFCs are operated under the scalar control algorithm. Functionality of the SDFC is analyzed in depth with the help of both HSPICE and EMTP programs. Laboratory test results from a 100 W prototype are also presented.
 W. J. Sarjeant, D. T. Staffiere, J. S. Bowers, N. Clark, I. Clelland, M. Hudis, W. P. Meskan, S. G. Parler, and J. Prymak, "Report on capacitors," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 12.
This report on capacitors and their relation to power electronics is the result of over two years of meetings, reviews, idea exchanges, philosophical discussion, agreements, and yes, occasional controversy. But, deeper, it represents findings and conclusions of career-long studies by those knowledgeable in the capacitor field. The study was conducted under the auspices of the Power Sources Manufacturer's Association (PSMA) in order to encourage wide and unrestricted dialogue among manufacturers, developers, and users of capacitors. The body of technology represented in the report suggests the formation of a forum for ongoing discussions on the state and future of the art.
 B. J. Seibel, T. M. Rowan, and R. J. Kerkman, "Field oriented control of an induction machine with dc link and load disturbance rejection," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 387.
A method of actively maintaining voltage margin in field oriented induction machine controllers is proposed. A voltage margin controller is developed that rejects dc link and load disturbances such that current regulation and field orientation is maintained. In addition, the voltage margin controller coupled with rotor flux oriented control is shown to provide maximum torque capability equivalent to stator flux oriented control.
 R. Severns, E. Yeow, G. Woody, J. Hall, and J. Hayes, "Ultra-compact transformer for a 100 w to 120 kw inductive coupler for electric vehicle battery charging," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 32.
A new generation of electric vehicles is being developed. A key problem to be solved is that of charging the batteries. One means of charging uses inductive coupling. The inductive coupling approach is essentially a transformer with a removable primary winding connected to a charging unit via a cable. The secondary and the core of the transformer are on the vehicle. This paper presents an inductive coupler which has been demonstrated delivering from 100 W to 120 kW continuously at a frequency of 75 to 120 kHz. The transformer is very compact (<100 in3). The primary purpose of this paper is a discussion of the power transformer. In addition the paper briefly addresses how the design of a magnetic device, which is usually a strictly technical exercise between engineers, is impacted when it is directly accessible to consumers in a mass market.
 F. Shi and A. Brockschmidt, "Fault tolerant distributed power," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 671.
Redundant power systems are used where safety or power availability is critical. An alternate approach is proposed and compared to present power system configurations. An example as applied to critical avionics on aircraft is presented, illustrating cost and weight savings in addition to improved power system performance.
 P. Singh, G. Galyon, K. Chu, S. Rao, and H. Larson, "Ion migration in a resistor network," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 731.
After a short time in service, resistor networks (R-pacs) in high current regulator circuits experienced decreasing resistance causing some power supplies to latch off. The root cause of the resistance decrease was determined to be ion migration on the R-pac alumina substrate, under the passivation oxide layer. The main corrective action was the replacement of the relatively porous passivation oxide layer with an essentially non-porous and acid resistant passivation oxide layer.
 T. H. Sloane and F. Mekanik, "Effects of line-failure phase angle in ferroresonant ups," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 716.
It is essential that a UPS transfer between line-mode powering and inverter-mode powering without any significant output transients. This paper uses a Spice model for the ferroresonant transformer to discuss the operation during these transitions. Model predictions are compared with laboratory data obtained from a microprocessor-controlled ferroresonant UPS.
 K. M. Smith and K. M. Smedley, "Comparison of voltage mode soft switching methods for pwm converters," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 291.
A comparison study was conducted to characterize the loss mechanisms, component stresses, and overall efficiencies of a group of voltage mode soft switching PWM methods including two improvement circuits developed at UCI. All soft switching methods in the selected group allow zero voltage turn-on and turn-off of the main switch and utilize a single auxiliary switch with some resonant components. Advantages and disadvantages were identified for each method. Experimental verification for each soft switching method were provided.
 J.-H. Song and S.-K. Sul, "Torque maximizing control of permanent magnet synchronous motor under voltage and current limitations of pwm inverter," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 758.
A method to improve torque capability of Surface Mounted Permanent Magnet Synchronous Motor (SPMSM) at a higher speed region, where the back emf of the motor is approaching to the voltage limit of a PWM inverter, is proposed. At this speed region a voltage vector laid on the boundary of hexagon limit of the voltage of PWM inverter is selected to optimally use the capability of the inverter and motor. The voltage vector, which gives maximum torque under the limitation of voltage and current, is calculated at the given operating condition in real time. The experimental results show that the operation speed by the proposed method can be extended to 45% compared to that of not using flux weakening scheme. Of flux weakening schemes, the speed by this proposed method can be extended 5% to 13%.
 R. L. Spyker, R. M. Nelms, and S. L. Merryman, "Evaluation of double layer capacitors for power electronic applications," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 725.
Advancement of double layer capacitor technology has made commercially available capacitors with capacitance values exceeding 470 Farads. This paper will present test results on double layer capacitors operating from DC to 50 kHz. Equivalent series resistance variation with frequency, duty cycle, polarity, load current, and charging voltage are examined, along with DC capacitance measurements and implementation in practical power electronic circuits.
 D. A. Stone, B. Chambers, and D. Howe, "Easing emc problems in switched mode power converters by random modulation of the pwm carrier frequency," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 327.
This paper presents a method of reducing the measured amplitude of the high frequency harmonics, contained in standard fixed frequency PWM, by the use of a pseudo-random binary sequence to modulate the PWM carrier frequency, achieving a spread spectrum effect on the EMC spectrum of the system.
 D.-B. Suh, J.-W. Choi, and S.-K. Sul, "Voltage gradient suppression in application of voltage-fed pwm inverter to ac motor drives - resonant dc link inverter approach," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 601.
In this paper, a hazardous phenomenon which occurs when the switching device of an inverter switches very fast or when a cable feeding a motor is very long is described and a suppression method for the voltage transition gradient of the voltage source inverter is presented. By using the resonant circuit in the dc link of the inverter, the inverter output voltage gradient at the switching moment can be suppressed. Compared to the hard switching inverter, the suppression of the voltage rise gradient and the performance of the proposed inverter in the control of the motor are verified through the experiment.
 J. Sun and H. Grotstollen, "Symbolic computation package for averaged analysis of power electronic systems," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 96.
A symbolic computation package for averaged modeling and analysis of switching power converters is presented. Starting from a netlist describing the topology of a converter, the package first generates the state-space models of the converter in different switch configurations. A general averaging method is then applied and an averaged model is automatically generated. The package is applicable to converters using different switching techniques, including hard switching, quasi-resonant soft switching, and soft transition.
 N. Sun and B. Hesterman, "Pspice high frequency dynamic fluorescent lamp model," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 641.
A new PSpice dynamic fluorescent lamp model based on high-frequency lamp characteristics is presented. The new model avoids convergence problems found when using the Mader-Horn lamp model. A systematic approach is developed to derive the lamp model parameters from experimental data. Simulations are shown to agree closely with experimental data.
 S. Tadakuma, S. Tanaka, H. Naitoh, and K. Shimane, "Improvement of robustness of vector controlled induction motors using feed forward and feedback control," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 405.
The authors propose a combined feed forward and feedback (FF/FB) control to improve robustness of vector controlled induction motors. This FF/FB system maintains the quick response of the slip-frequency type and is insensitive to parameter variation in cooperation with field orientation control. Furthermore the authors propose a neural network based vector control as a final goal of the FF/FB system.
 H. A. Toliyat, "Analysis and simulation of multi-phase variable speed induction motor drives under asymmetrical connections," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 586.
In this paper, a dq model based on transformation theory for five phase induction machines is presented. A detailed implementation of an indirect type five phase field orientation control including the hysteresis type PWM current regulator is described. A method for continuous and disturbance free operation of a five phase field oriented controlled induction motor drive with complete loss of one, two or even three legs of the inverter or motor phases is described. A complete analysis and computer simulation of this control technique is included.
 A. M. Tuckey and D. J. Patterson, "Design and development of a high power factor current source controller for small appliance brushless dc motors," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 778.
The harmonic content in utility supply current has increased recently due to the proliferation of devices using peak rectifiers. This paper presents a variable speed high power factor dc motor controller with application in small appliances. The circuit uses a single high-voltage high-frequency switching transistor in a buck converter topology. Theoretical analysis shows a large pulse width range giving a broad RFI/EMI spectrum. Experimental results verify the design with a 50 watt prototype controller having a power factor of 0.99.
 J. Underwood, M. Fitzgerald, and M. Cassidy, "Self-directed teams in power electronics manufacturing," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 64.
One of the principal concepts leading to continuous improvement at leading companies is employee empowerment. AT&T Power Systems is in the midst of a change to self-directed empowered teams in all functions. In the production environment, the entire nature of work is being transformed by a joint union and management initiative called Workplace of the Future (WPOF). The main component of the WPOF agreement is self-directed teams called Skilled Empowered Teams or SETs. This paper describes SETs, their purpose, the implementation process and their accomplishments.
 V. M. Van der Zel, M. J. Blewett, C. S. Clark, and D. C. Hamill, "Three generations of dc power systems for experimental small satellites," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 664.
The University of Surrey has launched 12 small satellites into orbit since 1981, demonstrating convincingly that low cost, reliable spacecraft can be engineered using standard components and techniques, as opposed to the expensive approach practiced by space agencies. Moreover, initial design to orbital operation takes only 12 to 18 months. The power system is a critical part of the spacecraft infrastructure. Three generations of satellite dc power systems are presented: the original system used on the 50 kg microsatellites UoSAT-1 and UoSAT-2; the system introduced on UoSAT-3 and used for current designs; and a new system for a 350 kg minisatellite due for launch in late 1996. The solar arrays, battery charge regulators, batteries, power processing and power distribution are described. Careful incremental development has ensured that no power system failure has occurred to date.
 M. S. Vilela, E. A. A. Coelho, J. B. Vieira, Jr., L. C. de Freitas, and V. J. Farias, "Pwm soft-switched converters using a single active switch," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 305.
This paper presents a new family of PWM soft-single-switched converters which, having only a single active switch, is able to operate with soft switching in a pulse with modulation way. In addition such converters can work in high switching frequencies for wide range of load without great duty cycle limitations. In order to illustrate the operating principle of these new converters a detailed study, including simulations and experimental test is carried out. The validity of these new converters is guaranteed by the obtained results.
 M. S. Vilela, E. A. A. Coelho, J. B. Vieira, Jr., L. C. de Freitas, and V. J. Farias, "Family of pwm soft-switching converters with low stresses of voltage and current," in