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|Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 984.|
Power source requirements for systems employing high performance microprocessors are analyzed and possible solutions are presented. Analysis and simulation show that the optimum converter switching frequency is dependant on the type of output capacitor used, which is generally selected to meet size versus cost goals. Proportional loop compensation is shown to result in a smaller peak to peak transient output voltage excursion than integral compensation. A new pair of ICs are introduced which are optimized for this application.
 S. Ohtsu, S. Muroyama, and K. Yamamoto, "Compact, high-efficiency and high-power-factor rectifier for telecommunications systems," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 509.
We have developed a rectifier which consists of a boost-chopper with zero-voltage switching and a full-bridge zero-voltage switching converter using bipolar-mode static induction transistors (B-SITs). A 5-kW-output experimental model achieved the following: high efficiency of 93%, high power density of 0.28 W/cm3, and its harmonic currents satisfy IEC standards.
 C. Oliveira and D. Maksimovic, "Zero-current-transition converters for high-power-factor ac/dc applications," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 159.
Zero-current-transition, discontinuous-conduction-mode (ZCT-DCM) converters are introduced in this paper. Compared to hard-switching (PWM) converters in DCM, the ZCT-DCM converters have similar current stresses and conduction losses, and much reduced turn-off switching losses. At the expense of increased voltage stresses, zero-current/zero-voltage switching is maintained for a wide range of loads and voltage conversion ratios without the need for auxiliary active devices. In ac/dc applications, high power factor is obtained automatically, without the need for active control over the input current. An experimental 100 kHz, 500 W ZCT-DCM Sepic rectifier with isolation transformer and single IGBT switch is described.
 J. C. Oliveira, L. C. De Freitas, E. A. A. Coelho, V. J. Farias, and J. B. Vieira, Jr., "Half-bridge pwm ac/ac converter," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 709.
This paper presents a PWM AC/AC Haft-Bridge circuit that, in the future, will be employed at the development of a stabilized voltage source. Principle of operation, theoretical analysis, design procedure is provided. The PWM AC/AC Half-Bridge have been validated by simulation and experimental results.
 V. M. Pacheco, V. J. Farias, J. B. Vieira, Jr., A. J. Nascimento, Jr., and L. C. de Freitas, "Quadratic buck converter with lossless commutation," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 311.
High switching frequency associated to soft commutation techniques is a trend in switching converters. Following this trend a buck PWM converter is presented, where the dc voltage conversion ratio has a quadratic dependence on duty-cycle, providing a large step-down. By introducing two resonant networks, soft switching is attained, providing high efficient operating condition for wide load range at high switching frequency. Contrarily to most of the converters that apply soft switching techniques, the switches are not subjected to high switch voltage or current stresses and, consequently, presenting low conduction losses. It is presented for this converter: the principle of operation, theoretical analysis, relevant equations and simulation and experimental results.
 Y. V. Panov and F. C. Lee, "Modeling and stability analysis of a dc power system with solid state power controllers," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 685.
A solid state power controller (SSPC) has become a popular element of a large-scale DC power system. An SSPC has a unique capability to limit short term overcurrent through the power device (MOSFET) operation in the active region. The device is controlled by a current feedback loop whose characteristics are shown to be strongly dependent on the SSPC load. The interaction between an SSPC control loop and a load converter can cause the instability, which was observed on the NASA Space Station hardware. The instability origin is revealed by the proposed small-signal SSPC model in the current limiting mode of operation. The MOSFET parasitic capacitances were demonstrated to play a crucial role in the influence of the load impedance on the SSPC dynamic behavior. Several design measures to decrease the SSPC loop sensitivity to the load are recommended. Small-signal analysis results are compared with the experimental data.
 P. N. Pasqua, "Power supply procurement, defining the value of your supplier, total cost of ownership," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 47.
Purchasers must be able to evaluate the total cost of procurement when choosing a custom switching power supply. This paper goes beyond the initial purchase price and explores the complex forces that can affect the total cost. Nineteen different parameters are identified, discussed, and quantified.
 S. Pendharkar and K. Shenai, "Circuit simulation model for high-power high-speed gaas schottky diodes," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 246.
This paper proposes a physically-based behavioral circuit simulation model for high-power GaAs Schottky diodes which is valid over all regions of operation. No conditional statements are needed to define the regions of operation. A new and more accurate method of obtaining depletion capacitance model parameters from the measured capacitance values is proposed. A simple current and temperature-dependent resistance model is used to model the non-linear diode resistance as well as the contact and packaging resistance. The validity of the model is demonstrated under various dc and transient switching conditions. Simulation results are compared with experimental data obtained from 200-V GaAs Schottky diodes. The diode model is tested at various temperatures in different test circuits and the simulation results are shown to be in excellent agreement with the measured data under both hard- and soft-switching conditions. The model is implemented in SABER, an advanced behavioral circuit simulator, but it can easily be implemented in other circuit simulators which have used defined mathematical equations.
 S. Pendharkar and K. Shenai, "Performance evaluation of high-power gaas schottky and silicon p-i-n rectifiers in hard- and soft-switching applications," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 234.
The dynamic switching characteristics of 200 V high-power GaAs Schottky and silicon P-I-N rectifiers are studied at various temperatures under both hard- and soft-switching conditions. Devices were first characterized to measure forward and reverse I-V, C-V, reverse breakdown voltage and reverse recovery performances. The same devices were characterized for turn-on and turn-off in switching circuits designed to study the dynamic switching performances under hard- and soft-switching conditions at different temperatures. Advanced finite element based mixed device and circuit simulations were used to study the internal plasma dynamics under boundary conditions imposed by circuit operation. It is shown that, for hard-switching applications, GaAs Schottky power rectifiers exhibit significantly reduced switching power losses compared to silicon P-I-N rectifiers. For soft-switching applications, there is no significant difference in the switching power losses for these two devices. Diode performance at elevated temperatures is studied and the temperature dependencies of switching and conduction power losses are analyzed.
 A. A. Peteira, E. A. A. Coelho, V. J. Farias, L. C. de Freitas, and J. B. J. Vieira, "New zc-zvs forward converter," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 482.
This paper will present a steady-state analysis with complete characterization of the converter operation. The non-dissipative snubber associated with a Forward converter provides the soft commutation switching. The proposed approach allows building a converter with high frequency operation. A detailed analysis of the operation will be presented. The output voltage is controlled by PWM with a constant frequency. The complete operating principles, theoretical analysis, relevant equations, simulation results and the experimental results will be presented.
 R. Prieto, O. Garcia, R. Asensi, J. A. Cobos, and J. Uceda, "Optimizing the performance of planar transformers," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 415.
Planar transformers are a good solution for high frequency switching-mode power supplies (SMPS). Since these kind of transformers have some advantages that improve the SMPS performance, their use is growing in the last years. Some of the high frequency parasitics can be drastically reduced due to their planar geometry and the proximity of the windings. This work presents a study of different structures and winding strategies using a standard procedure to build planar transformers. This standard method makes easier and cheaper the transformer construction by means of a standard set of layers. The paper presents a study of the influence of the parasitic effects, the advantage of the interleaving technique depending on the magnetic component role, the advantage of these transformers in multiwinding applications and the use of planar transformers in different topologies. The study is carried out by means of a Finite Element Analysis (FEA) procedure, not only by the inspection of the flux and current distribution, but generating models that take into account all the geometry and frequency effects. Design guidelines and some experimental results are also included in this paper.
 Y. Qin and S. Du, "Control of single phase power factor pre-regulator for an on-line uninterruptible power supply using fuzzy logic inference," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 699.
A Fuzzy Logic inference control scheme is proposed and applied in control of a power factor corrected (PFC) pre-regulator used in a high performance on-line uninterruptible power supply (UPS). Since the performance of a fuzzy logic controller only depends on the selection of membership functions and the inference of fuzzy rules, and fuzzy set theory, in natures, is capable of working with non-linear systems, thus fuzzy logic controllers have an advantage in coping with the time varying non-linearity of switches in PFC pre-regulator, and it does not require an accurate mathematical model of the PFC pre-regulator when controller is designed. This fuzzy logic controller used for PFC pre-regulator has been realized by using a 16 bit Digital Signal Processor (DSP). Experimental verifications have been carried out on a 3 kVA UPS. The experiment results show that the fuzzy logic inference based controller can achieve both good dynamic response and low Total Harmonic Distortion (THD) under large load disturbance and plant uncertainties.
 J. Rajagopalan, K. Xing, Y. Guo, F. C. Lee, and B. Manners, "Modeling and dynamic analysis of paralleled dc/dc converters with master-slave current sharing control," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 678.
A simple, application-oriented, transfer function model of paralleled converters employing Master-Slave Current-sharing (MSC) control is developed. Dynamically, the Master converter retains its original design characteristics; all the Slave converters are forced to depart significantly from their original design characteristics into current-controlled current sources. Five distinct loop gains to assess system stability and performance are identified and their physical significance is described. A design methodology for the current share compensator is presented. The effect of this current sharing scheme on `system output impedance' is analyzed.
 B. Ray, S. S. Gerber, R. L. Patterson, and J. E. Dickman, "Low temperature performance of a boost converter with mpp and hts inductors," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 883.
Low temperature performance of a 150 W, 50 kHz, 24/48 V boost PWM dc-to-dc converter is reported. The efficiency of the converter using a molypermalloy powder (MPP) core based inductor went up from 94% at room temperature (23 °C) to 95.9% at liquid nitrogen temperature (-196 °C). A BSCCO based high temperature superconducting (HTS) inductor with a transition temperature of approximately -158 °C was compared to a MPP core based inductor in terms of the power converter performance at liquid nitrogen temperature. The use of the HTS inductor in the converter tested yielded no significant performance improvement over the same converter with the MPP inductor. The experimental results are discussed along with the HTS inductor characteristics.
 R. Redl, A. S. Kislovski, and B. P. Erisman, "Input-current-clamping: An inexpensive novel control technique to achieve compliance with harmonic regulations," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 145.
This paper introduces a new simplified control technique for high-quality rectifiers. The technique, called `input-current-clamping,' requires only a low-cost controller, while it ensures compliance with existing harmonic regulations. We present the regulations, the idealized waveforms obtainable with the proposed technique, the spectra of those waveforms, the maximum compliant power for the different waveforms, and the real waveforms obtainable with the boost and the buck rectifier circuits, when the duty ratio is limited to less than unity. We also present experimental results for a boost circuit.
 J. G. Renauer, "Challenges in powering high performance, low voltage processors," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 977.
Today's high performance processors require power supplies that can deliver low voltages at high currents with extremely tight voltage tolerances even in the presence of lighting fast load changes. High performance processors demand high performance power supplies. This paper addresses some of the design and component selection issues the system engineer must face in designing with linear or switching regulators.
 G.-H. Rim, I. Kang, W.-H. Kim, and J.-S. Kim, "Shunt hybrid active filter with two passive filters in tandem," in Proceedings of IEEE Applied Power Electronics Conference and Exposition, 1996, pp. 361.
The harmonic related problems in the utility is increasing with the proliferation of nonlinear loads such as power converters in industrial applications. Filtering options such as passive, active and hybrid filters are countermeasures against these problems. In this study, a novel hybrid active filter topology with a new approach to enhance the system performance is presented. The proposed topology comprises two passive filter stages, in tandem, and an active filter in series. It improves the system efficiency and reduces VA ratings, hence, overall filtering cost. The system operation, control and experimental verification on a three phase diode bridge rectifier are presented.
 G.-H. Rim, W.-H. Kim, and J.-G. Cho, "Zvt single pulse-current converter for switched reluctance motor drives," in