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Applied Power Electronics Conference and Exposition, 1997. APEC '97 Conference Proceedings 1997., Twelfth Annual

Date 27-27 Feb. 1997

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  • Twelfth Annual Applied Power Electronics Conference And Exposition [front matter]

    Publication Year: 1997 , Page(s): i - xxii
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    Freely Available from IEEE
  • Author index

    Publication Year: 1997 , Page(s): 1069 - 1070
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    Freely Available from IEEE
  • Soft switching power amplifiers for audio applications

    Publication Year: 1997 , Page(s): 799 - 804 vol.2
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    This work presents a soft switching power amplifier, for audio applications, which uses PWM techniques. The principles of power switching amplifiers are described. The design procedure, simulation and experimental results for soft commutation are presented. The final goal of this study is to obtain a laboratory prototype of a switching power amplifier with soft commutation, which presents high efficiency and high audio fidelity View full abstract»

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  • A new instantaneous torque control of PM synchronous motor for high performance direct drive applications

    Publication Year: 1997 , Page(s): 721 - 727 vol.2
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    A new instantaneous torque control strategy is presented for the high performance control of a permanent magnet synchronous motor. In order to deal with the torque pulsation problem of the PM synchronous motor in the low-speed region, new torque estimation and control techniques are proposed. The linkage flux of the PM synchronous motor is estimated using a model reference adaptive control system technique and the developed torque of the motor is instantaneously controlled by a torque controller combining variable structure control with space vector PWM. The proposed control scheme provides the advantage of reducing the torque pulsation caused by the nonsinusoidal flux distribution of the motor. This control strategy is applied to a high torque PM synchronous motor drive system for direct drive applications and implemented by using a software of the DSP TMS320C30. Computer simulations and experiments are carried out for this system and the results demonstrate well the effectiveness of the proposed control strategy View full abstract»

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  • Application of neural networks to a disc motor with offset rotor

    Publication Year: 1997 , Page(s): 709 - 714 vol.2
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    Axial field permanent magnet disc machines are attractive for direct wheel drives in electric vehicles because the stators can be mounted on the vehicle body whilst the rotor can be directly coupled to the driven wheel. However, this arrangement gives rise to torque pulsations in the drive due to the perturbation of the wheel by the road surface effects. It is shown here that torque pulsations due to the rotor perturbation can be eliminated by modulation of the input motor current based on flux identification determined by a neural network View full abstract»

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  • Optimized linear contactless power transmission systems for different applications

    Publication Year: 1997 , Page(s): 953 - 959 vol.2
    Cited by:  Papers (1)  |  Patents (1)
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    Linear contactless power transmission systems are proposed as alternative power supplies to mobile loads used in harsh environments. Such systems comprise a core with a secondary winding sliding along an extended primary winding. In long applications the transformer primary winding is the most limiting component in the system whereas in short applications the transformer core size is usually the detrimental factor. Formulas to optimize and design sliding transformers for different applications are given. The implementation of these formulas are then illustrated by designs for three different applications. Experimental waveforms for a 5 m, 15 kVA sliding transformer are presented View full abstract»

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  • Low flicker universal power converter for filament-based heating processes

    Publication Year: 1997 , Page(s): 1062 - 1068 vol.2
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    For filament-based heating processes, a minimum-component power converter topology with a universal line voltage interface virtually eliminates flicker. It provides asynchronous linear power control, with unity power factor and low harmonic content over a wide range of power levels. With common control methods, it exploits the natural behavior of filament-based heating processes. The topology is derived, its linear power control is developed and simulated and its experimental performance is presented View full abstract»

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  • Operation analysis of the push-pull piezoelectric inverter

    Publication Year: 1997 , Page(s): 573 - 578 vol.2
    Cited by:  Papers (8)  |  Patents (1)
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    Operation of the push-pull inverter with a piezoelectric transformer is analyzed. The piezoelectric transformer is used in the third-order longitudinal vibration mode to produce a high output voltage to light up a cold cathode fluorescent lamp. The load characteristics of the inverter are analyzed using an equivalent circuit of the piezoelectric transformer. The ZVS conditions are derived using simplified equivalent circuits to determine the ZVS operation region. These analytical results are confirmed by experiments View full abstract»

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  • Design of very low profile magnetic components using flex foils

    Publication Year: 1997 , Page(s): 561 - 567 vol.2
    Cited by:  Papers (7)
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    Several magnetic components (transformers and inductors) have been designed with very low profile (4 mm height) cores. To achieve such a low height, full custom cores have been used, together with an advanced technology (flex foils) for the windings. This freedom in the selection of dimensions and materials makes the design procedure completely different to the traditional schemes with commercial cores. The process used to obtain an optimum design is described in this paper. It is based on the use of models based on finite element analysis (FEA) tools, and spreadsheets. This procedure has been applied to the design of a transformer and an inductor, with a size of 10×10×4 mm3 for each, to be used in an onboard power converter in telecommunication systems. Experimental results of a 5 W, low output voltage (3.3 V×1.5 A) prototype with these magnetic components are included in the paper View full abstract»

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  • A novel three-phase three-switch three-level high power factor SEPIC-type AC-to-DC converter

    Publication Year: 1997 , Page(s): 657 - 665 vol.2
    Cited by:  Papers (10)
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    In this paper, the topology of a new three-phase three-switch three-level PWM rectifier system is derived based on the basic structure of a DC-to-DC SEPIC power converter. The system is characterized by full controllability of the power flow (independent of the level of the output voltage) and by a sinusoidal mains current shape in phase with the mains voltage. The operating principle of the power converter is explained based on the conduction states of a bridge leg within a pulse period. The stationary operating behavior is analyzed by digital simulation based on the control of the mains phase currents by independent ramp-comparison controllers. Furthermore, a mathematical description of the operating behavior of the three-phase system including the coupling of the phase current controllers (given due to the floating mains star point) is discussed. Finally, results of an experimental investigation of a laboratory model of the power converter are presented View full abstract»

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  • New piezoelectric transformer converter for AC-adapter

    Publication Year: 1997 , Page(s): 568 - 572 vol.2
    Cited by:  Papers (16)  |  Patents (1)
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    A new piezoelectric transformer (PT) converter which functions as an AC-adapter is proposed. The device's PT operates in longitudinal-vibration mode and features good isolation, incombustibility and compact size. The PT was implemented as a part of the new AC-adapter and a significant reduction in size was achieved as a result. Experimental evaluation of the new adapter confirms that good performance was successfully obtained in spite of the need to comply with strict safety and noise standards View full abstract»

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  • An improved ZVZCS PWM FB DC/DC converter using energy recovery snubber

    Publication Year: 1997 , Page(s): 1014 - 1019 vol.2
    Cited by:  Papers (6)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The conventional high frequency phase-shifted full-bridge DC/DC power converter has a disadvantage that a circulating current flows through the transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free-type high-frequency ZVZCS phase-shifted full bridge (FB) DC/DC power converter with an energy recovery snubber attached at the secondary side of transformer. The energy recovery snubber adopted in this study is consisted of three fast recovery diodes and two resonant capacitors View full abstract»

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  • Simulation and modeling of a DC-DC converter controlled by an 8-bit microcontroller

    Publication Year: 1997 , Page(s): 963 - 969 vol.2
    Cited by:  Papers (17)
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    Traditionally, analog control technologies have been employed to regulate the output voltage of DC-DC converters. The utilization of digital control techniques for this regulation function is currently under consideration. Critical issues in a digital control implementation include analog-to-digital conversion range, resolution and delay, calculation time, and numerical precision. Results from an investigation into the modeling and simulation of DC-DC converters controlled by an 8-bit microcontroller are described in this paper. Many of these critical issues have been modeled using MatlabTM and Simulink TM from The Mathworks Inc. Simulation results from this model are compared to experimental waveforms obtained from a buck converter controlled by a Microchip PIC16C74 8-bit microcontroller. Experimental results agree well with the simulation model. The buck converter is represented by its state-space averaged model in the simulation View full abstract»

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  • A high performance generalized discontinuous PWM algorithm

    Publication Year: 1997 , Page(s): 886 - 894 vol.2
    Cited by:  Papers (25)  |  Patents (2)
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    In this paper a generalized discontinuous pulse width modulation (GDPWM) method with superior high modulation operating range performance characteristics is developed. An algorithm which employs the conventional space vector PWM method in the low modulation range, and the GDPWM method in the high modulation range is established. As a result, the current waveform quality, switching losses, voltage linearity range and the overmodulation region voltage gain of a PWM-VSI drive are optimized online as opposed to conventional modulators with fixed characteristics. Due to its compactness, simplicity and superior performance, the algorithm is suitable for most high performance PWM-VSI drive applications. The paper provides a detailed performance analysis of the method and compares it to the other methods. Experimental results verify the superiority or this algorithm to conventional PWM methods View full abstract»

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  • Electrical modeling of HF coupled inductors supplying a double frequency inductive plasma reactor

    Publication Year: 1997 , Page(s): 937 - 943 vol.2
    Cited by:  Papers (1)
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    A new inductive plasma reactor has been developed for metal coating. It combines magnetic plasma generation at 13.56 MHz and induction heating at 100 kHz. The unavoidable coupling of the two coaxial coils allows one electrical generator to force power in the other, compromising the reliability of the system, except if rejecting filters are inserted. Therefore, an equivalent circuit of the double coil set is needed to specify and design the necessary filters. The aim of this paper is to present and justify the electrical representation of this very special high frequency transformer which have been used successfully View full abstract»

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  • Robust control of single phase UPS

    Publication Year: 1997 , Page(s): 825 - 831 vol.2
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    This paper deals with the design of a robust control scheme for single phase uninterruptible power supplies (UPS). UPS systems must provide sinusoidal output voltage irrespective of operating conditions, e.g. in presence of nonlinear and variable loads. In this paper, variations of the operating conditions are modelled as perturbations of the plant transfer function, so that control design can be approached by robust control techniques. Modelling plant and perturbations according to the linear fractional transformation (LFT) standard structure, allows the use of μ-synthesis to design a robust controller, able to guarantee the specified performances in any operating condition, including nonlinear or step-changing loads. In addition, the paper shows how the main drawback of the robust controller, that is its high order, can be compensated by order reduction techniques, thus allowing a simple implementation. The superiority of the reduced order robust controller is demonstrated by a comparison with a conventional controller View full abstract»

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  • Improved digital control scheme of three phase UPS inverter using double control strategy

    Publication Year: 1997 , Page(s): 820 - 824 vol.2
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    A novel digital control scheme of a UPS inverter based on the double control strategy is proposed. This method consists of a inner voltage regulated current controller and an outer current regulated voltage controller. In order to improve the dynamic response, the voltage controller has a load predictive feedforward loop and the current controller has an output voltage feedforward loop. PI compensators included in each of the voltage and current controllers are used to guarantee the robustness of the system. The mathematical model and the control algorithm of the proposed scheme are described and digital simulation and experimental results for a 5 kVA prototype are provided to verify the validity of the proposed double control strategy View full abstract»

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  • Analysis and design of a high power factor, single-stage electronic ballast with dimming feature

    Publication Year: 1997 , Page(s): 1030 - 1036 vol.2
    Cited by:  Papers (26)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    The analysis, design and practical consideration of a single-stage electronic ballast with a dimming feature and unity power factor are presented in this paper. The proposed single-stage ballast is the combination of a boost power converter and a half-bridge series-resonant parallel-loaded inverter. The boost semi-stage, working in the discontinuous conduction mode, functions as a power factor corrector and the inverter semi-stage, operated above resonance, is employed to ballast the lamp. Replacing the lamp with a plasma model, analysis of the ballast is fulfilled. The dimming feature is carried out by using pulse-width modulation and variable-frequency controls simultaneously. The proposed ballast can save a controller, reduce size and possibly increase system reliability over a conventional two-stage system. A prototype was implemented to verify the theoretical discussion. The hardware measurements have shown that the desired performance can be achieved feasibly View full abstract»

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  • Capacitors as an element in advanced power sources in power electronics systems

    Publication Year: 1997 , Page(s): 596 - 601 vol.2
    Cited by:  Papers (1)
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    As consumer and industrial requirements for compact, high power density, electrical power systems grow substantially over the next decade, development of high power/energy density capacitor technology is a major enabling technology component element. This paper describes the results of a continuing study of the Power Sources Manufacturer's Association Capacitor R&D Committee of capacitor technologies for microsecond to fractional-second electrical energy storage, discharge, filtering and power conditioning applications. For such applications, capacitor technology is unequalled in flexibility and adaptability to meet a broad range of requirements in the future View full abstract»

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  • Design considerations and performance evaluations of synchronous rectification in flyback converters

    Publication Year: 1997 , Page(s): 623 - 630 vol.2
    Cited by:  Papers (9)  |  Patents (6)
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    Design trade-offs and performance comparisons of various implementations of the flyback power converter with a synchronous rectifier are presented. Specifically, the merits and limitations of the constant-frequency (CF) continuous-conduction-mode, CF discontinuous-conduction-mode (DCM), variable-frequency DCM, and zero-voltage-switched DCM flyback power converters with synchronous rectifiers are discussed. The theoretical efficiency improvements of the discussed synchronous rectification approaches relative to Schottky diode implementations are derived. Finally, theoretical results are verified on an experimental, universal-input, offline, 15 V/36 W flyback prototype View full abstract»

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  • Fuzzy logic control of a space vector PWM current regulator for three phase power converters

    Publication Year: 1997 , Page(s): 879 - 885 vol.2
    Cited by:  Papers (1)
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    This paper presents a fuzzy logic control scheme of space vector pulsewidth modulation (PWM) for three-phase power converters. The conventional space vector PWM current regulator implementation is generally computationally complex. The fuzzy logic controller implementation relieves the processor of a number of computations, thereby accommodating a less expensive microprocessor. The AC side rectifier voltages are used as fuzzy state variables. The fuzzy logic control has two outputs: magnitude; and angle of reference voltage. Both conventional space vector PWM and the fuzzy logic controller are implemented to evaluate performance using 16-bit microcontroller (68HC16). Experimental results are provided for both controllers at the same operating point, where the power drawn by the load is about 3 kW. The fuzzy logic controller reduces the computational burden on the processor by about 30% View full abstract»

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  • Design of high efficiency, low profile, low voltage converter with integrated magnetics

    Publication Year: 1997 , Page(s): 911 - 917 vol.2
    Cited by:  Papers (44)  |  Patents (37)
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    This paper presents an innovative design for a high efficiency, low profile, low voltage DC-DC power converter module intended for card mounted applications in a distributed aircraft power system. An innovative integrated magnetic structure for the half-bridge power converter lumps all the magnetic components into one structure and reduces the number of magnetic terminations. By incorporating advanced hybrid power packaging with the proposed integrated magnetic technique, a preliminary hybrid module of 1.6"×2.0" footprint and 0.21" height was developed. An overall efficiency (including the control circuit and power stage) of 90% was achieved for a 3.3 V, 100 W output operating at a 500 kHz switching frequency. The new integrated magnetic structure can be extended to other topologies View full abstract»

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  • Primary saturable inductor for high power zero voltage switching DC-DC converter with IGBTs

    Publication Year: 1997 , Page(s): 944 - 947 vol.2
    Cited by:  Papers (1)
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    The use of additional capacitors and a resonating inductor with a bridge converter can allow zero voltage switching in high-power slow-switching applications. The performance can be further improved if a saturable reactor is used. This paper examines the design of such a saturable reactor and presents experimental results from a 3 kW, 30 kHz IGBT DC-DC converter View full abstract»

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  • Vector control of interior permanent magnet synchronous motor without a shaft sensor

    Publication Year: 1997 , Page(s): 743 - 748 vol.2
    Cited by:  Papers (4)  |  Patents (1)
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    This paper describes the two control techniques to perform the sensorless vector control of interior permanent magnet synchronous motors (IPMSM) by injecting the high frequency voltage to the stator terminal. The first technique is the estimation algorithm of the rotor initial position including the identification of the rotor magnet N-S polarity at standstill. IPMSM possess the saliency which produces the ellipse of the stator current when the high frequency voltage is injected to the motor terminal. The major axis angle of the current ellipse gives rotor position information at standstill. The center of the current ellipse shifts because of the magnetic saturation effect from the origin, which makes it possible to identify the rotor magnet N-S polarity. The averaging method of the multi-cycles stator current is utilized to identify the rotor magnet N-S polarity. This averaging method increases the accuracy of the position estimation and solves the current ripple problem. The second control technique is a sensorless control algorithm that injects the high frequency current to the stator terminal in order to estimate the rotor position and speed. The rotor position and speed for sensorless vector control is achieved by appropriate signal processing to extract the position information from the stator current even in the low speed range. Experimental results are presented to verify the feasibility of the proposed control schemes View full abstract»

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  • Analysis and control design of paralleled DC/DC converters with current sharing

    Publication Year: 1997 , Page(s): 638 - 646 vol.2
    Cited by:  Papers (10)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    The paper presents a general small-signal stability analysis of a paralleled DC/DC power converter system. The framework is specialized in order to include both the “democratic” and “master-slave” current-sharing schemes. Design examples illustrate how to obtain stable current sharing. The authors show how paralleled power converters can become unstable (even when active current-sharing is absent) and discuss the influence of the number of power converters paralleled View full abstract»

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