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Applied Power Electronics Conference and Exposition, 1988. APEC '88. Conference Proceedings 1988., Third Annual IEEE

Date 1-5 Feb. 1988

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Displaying Results 1 - 25 of 42
  • APEC '88: Third Annual IEEE Applied Power Electronics Conference and Exposition. Conference Proceedings 1988 (Cat. No.88CH2504-9)

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    Freely Available from IEEE
  • Limitations of the magamp regulator and an improved magamp choke design procedure

    Page(s): 109 - 117
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    Some inherent limitations of the magamp regulator are examined, and their effect on square-loop choke design is explained. One effect is that the commonly used area product design and method may not produce a core which will regulate properly. A core design procedure that includes these factors and utilizes the core volume as well as the area product for optimizing core size and core loss is developed. The impact of choke parameters on loop performance is demonstrated.<> View full abstract»

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  • Analysis and design of a high frequency parallel resonant converter operating above resonance

    Page(s): 182 - 189
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    A high-frequency link DC/DC converter using a parallel-resonant inverter and operating above resonance is analyzed using the state-space approach and constant-current model. Closed-form solutions are obtained under steady-state conditions. The analysis shows that most equations are of almost the same form as those corresponding to operations below resonance. The analysis presented is used to obtain design curves and to provide a simple design procedure which is illustrated by a design example. Experimental results obtained with a prototype unit, which uses MOSFETs as switches and operates above 90 kHz, are presented to support the theory View full abstract»

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  • Power supply circuit development estimating aid: an expert system application

    Page(s): 64 - 71
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    A power supply circuit development estimating aid has been developed using an expert-system shell. The aid uses a detailed work-plan method to generate its estimate. Applications include training in the power-supply circuit development process, providing templates for a disciplined approach to power-supply circuit development, and producing a tool for exploring methods of reducing the cost of power-supply circuit development View full abstract»

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  • Analysis and design of a novel 3-φ solid-state power factor compensator and harmonic suppressor system

    Page(s): 267 - 277
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    A three-phase solid-state power-factor-compensation scheme is presented and analyzed. This scheme employs a PWM voltage-source inverter and has two important features: it can maintain a near-unity mains input power factor without sensing and computing the associated reactive power component, and it can substantially reduce any line current harmonics generated by nonlinear loads. The proposed scheme is discussed in terms of principles of operation, power system design, and analysis under unbalanced operating conditions. Predicted results are in agreement with experimental results View full abstract»

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  • Sequential switching series resonant converter with phase shift control

    Page(s): 190 - 199
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    Properties of a two-section phase-shift-controlled sequential switching series-resonant converter with (and without) mutually coupled tank inductors are discussed. Results of computer simulation and prototype evaluation show that the low semiconductor switching stresses, typical of all resonant converters, are further reduced in this topology, and that highly reliable operation is indicated. Comparisons with conventional phase-shift-controlled topologies (i.e. without sequential switching) and with a PWM series-resonant converter are also presented View full abstract»

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  • SPICE models for power MOSFETs: an update

    Page(s): 281 - 289
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    Five existing power MOSFET models intended for use with SPICE simulations are reviewed and compared. Methods used for simulating the gate-drain capacitance are evaluated. The internal JFET employed in two of the models is found to be usually unnecessary. A simple two-value capacitance model is recommended. The performance of this model is demonstrated with data obtained from 200 kHz forward converter View full abstract»

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  • Zero-voltage switching in high frequency power converters using pulse width modulation

    Page(s): 33 - 40
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    A zero-voltage switching technique is described that utilizes a resonant transition during a short but finite switching interval. This zero-voltage resonant-transition (ZVRT) switching technique can be applied to conventional buck, boost, and buck-boost power converter topologies that operate with a constant switching frequency and use pulsewidth modulation for output control. Since frequency-dependent losses are greatly reduced in the power transistors, efficient operation at higher switching frequencies (>1 MHz) is allowed. However, conduction losses are increased because ripple currents are increased and synchronous rectification is required. Experimental results are presented for an interleaved flyback converter that operates with ZVRT switching at 1 MHz View full abstract»

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  • Zero-voltage switching in a constant frequency digitally controller resonant DC-DC power converter

    Page(s): 360 - 367
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    A series-resonant DC-DC converter operating at a constant frequency above its resonant frequency is analyzed and experimentally tested. Using a state-plane analysis, the range of load for a given set of circuit parameters over which zero-voltage zero-current turn-on and zero-voltage turn-off (using lossless capacitive snubbers) are calculated and verified on a test circuit. A digital controller, designed previously for a quantized duty-ratio control in PWM DC-DC converters and now available in a gate array, is used to implement the constant-frequency control of the output voltage View full abstract»

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  • MODADEC: a VLSI circuit adapted to any kind of 2 levels PWM modulation

    Page(s): 130 - 138
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    A new VLSI circuit which was developed to drive inverter-fed AC motors is described. It has been conceived as a peripheral of a microprocessor and offers a wide choice of PWM modes and strategies. The steady-state PWM waveforms are generated with high precision on the instant of commutation. The IC has high-frequency performances and can handle different optimizations of transients when changing PWM modes. The circuit is suitable for variable-speed applications, from servo-applications where a high commutation frequency and fast dynamic are required to high-power traction applications, where it is imperative to have smooth transitions and perfect torque control View full abstract»

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  • New insights affect power MOSFET ruggedness

    Page(s): 290 - 298
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    Issues affecting unclamped inductive switching (UIS) and diode recovery stress (DRS) failure modes of power MOSFET devices are discussed in terms of a modified device equivalent circuit. Test methods for both UIS and DRS are described; a useful format for device DRS capability is also described. The effect on switching efficiency of stored minority carrier charge in the MOSFET source-drain diode is highlighted View full abstract»

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  • Isolated feedback for off-line switching power supplies with primary-side control

    Page(s): 203 - 211
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    Safety regulations require galvanic isolation between the AC line voltage and the outputs of switch-mode power supplies, making implementation of the feedback-control loop difficult. Four existing schemes for providing feedback information across the isolation barrier are examined. The schemes are identified as opto-couplers, amplitude modulation of the error signal, amplitude modulation of the output voltage, and communication of the drive pulse across the barrier. Each is examined with regard to steady-state and frequency-domain considerations View full abstract»

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  • A new 200 A, 500 V cascade BIMOS power module for high power and high frequency inverter applications

    Page(s): 226 - 235
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    The development of a high-power cascade BIMOS module is reported. A cascade BIMOS is a Darlington configuration of a high-voltage MOSFET and a bipolar transistor of equal voltage rating, where the MOSFET constitutes the input stage and drives the output-stage bipolar transistor. The module is rated at 500 V, 200 A and is designed for high-power and high-frequency operation. The merits of the module are illustrated by means of various static and dynamic characteristics, ratings and performances View full abstract»

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  • UC1860-new IC controls resonant mode power circuits

    Page(s): 299 - 307
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    A novel integrated circuit, the UC1860, is introduced. Its prime purpose is to provide the control function in resonant mode power supplies operating at frequencies up to 3 MHz. A frequency-modulated, fixed on-time control scheme is implemented. Additional features include a programmable under-voltage lockout circuit and a programmable soft-start/hiccup circuit View full abstract»

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  • Design and control of a full-wave, quasi-resonant flyback converter

    Page(s): 41 - 49
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    A full-wave zero-voltage switching quasiresonant converter flyback converter with a novel multiloop control was built which operates over the range of input voltage and load of a typical distributed-system power supply. The maximum converter frequency of 880 kHz is shown to be close to the practical limit for this specific application. Reasonable full-load efficiency is achieved, and the predicted losses agree with actual circuit measurements. The multiloop control scheme provides noise-immune and stable control over the full operating range of the converter. Design guidelines for the control are given, and it is shown theoretical and measured small-signal performance are in agreement. Performance and stress predictions are also very close to measurements View full abstract»

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  • Coupled-inductor rectification and cycloconversion

    Page(s): 258 - 266
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    AC-to-DC rectifiers and polyphase AC-to-DC cycloconverters are derived from the basic DC-to-DC converters by the addition of negatively coupled inductors with a minimal number of switching devices. The circuits also use space and time-multiplexed magnetics to handle the multiple inputs and outputs. The application of current-programming linearizes the duty ratio control, improves the output and input waveforms, reduces the small-signal transfer function to a first-order system, and speeds the response to pulse-load variations View full abstract»

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  • Zero-voltage-switching technique in high-frequency off-line converters

    Page(s): 23 - 32
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    Zero-voltage switching (ZVS) is implemented using a half-bridge (HB) topology for high-frequency offline applications. Two ZVS techniques are discussed: one is a quasiresonant technique (QRC) the other a multiresonant technique (MRC). A breadboarded HB ZVS-QRC is presented which operates from a 300±50 V input with maximum output power of 75 W (5 V, 15 A) and an efficiency of 83.5% at low line and full load and 79.2% at high line and full load. In ZVS-MRCs, all semiconductor devices are operated with no abrupt changes of the voltage across the devices. The technique permits utilization of junction capacitances of all semiconductor devices and the transformer leakage inductance to form a multiple-resonant-tank network to implement zero-voltage switching for all semiconductor devices. Employing this technique, a HB ZVS-MRC is breadboarded with the same specifications as the HB ZVS-QRC. The efficiency of the HB ZVS-MRC is slightly lower than that of the HB ZVS-QRC, 81.7% at full load and low line and 78.5% at full load and high line View full abstract»

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  • Regenerative power control for VVVF motor drive (critical braking method applied to the elevator)

    Page(s): 97 - 105
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    A method for braking induction motors is described. The method, called critical braking, consumes the regenerative power within the rotor and stator windings of the induction motor itself. Critical braking is realized by maintaining the induction motor slip at a constant value at which the regenerative power and the consumed power in the windings balance. A practical control system is described that applies this principle to a motor drive for elevator applications View full abstract»

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  • 60 to 600 volt input DC to DC converter

    Page(s): 212 - 216
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    A DC to DC converter that converts an unregulated field excitation voltage to a regulated DC voltage (40 V, 1.8 A) with 10 kV isolation is described. The output of this DC to DC converter powers the rotor mounted electronics of a continuous-measurement monitor. The environment is 25-65°C and 50-300 Gs (steady state) resulting from centrifugal forces View full abstract»

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  • High field properties of nickel-zinc ferrites at 1-10 MHz

    Page(s): 311 - 318
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    The design of compact and efficient magnetic components for 1-10 MHz power conversion has been hindered by the lack of permeability and loss data for nickel-zinc ferrites. A technique for measuring permeability and loss density in magnetic materials at high-frequency and high-flux levels is described. Data is presented for eight commercially available nickel-zinc ferrites at 25°C, operating at frequencies between 1 and 10 MHz, and at flux levels up to 300 G. Loss density was found to increase with frequency and flux level. High-loss density limits practical flux levels to less than 300 G. The higher permeability materials generally displayed higher loss. Indiana General Q1 ferrite was found to have the lowest loss in response to a purely AC excitation; DC offset increased loss density View full abstract»

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  • A new family of resonant rectifier circuits for high frequency DC-DC converter applications

    Page(s): 12 - 22
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    A family of rectifiers suitable for operation at high frequencies is presented. These rectifiers use naturally occurring component parasitics to control diode switching thereby minimizing parasitic ringing and improving rectification efficiency by reducing the flow of harmonic currents. The input impedance of the resonant rectifier is linear, which makes possible an accurate adjustment of the rectifier to present the proper load impedance to an inverter. When a resonant rectifier is coupled to a resonant inverter in this manner, a fully resonant DC-to-DC converter is produced. With these circuits it is possible to achieve a very low input/output ripple and EMI since voltages and currents seen by the filters are confined to a very narrow frequency range compared to conventional squarewave converters View full abstract»

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  • Variable speed induction motor with integral ultrasonic PWM inverter

    Page(s): 92 - 96
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    A variable-speed motor made by integrating an inverter into the end cowling of a modified induction motor is described. The inverter strategy is PWM, based on a 20 kHz asynchronous carrier and uses FREDFET (fast recovery epitaxial diode FET) power switches. Other characteristics are the addition of a third harmonic for greater output voltage and a novel technique for smooth reversing View full abstract»

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  • Duomode non-linear state space averaged SPICE model of a current mode buck converter

    Page(s): 53 - 58
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    Although most current-programmed converters are designed for steady-state continuous mode operation, transient and fault analysis require dual-mode (continuous/discontinuous) models. The popularity of SPICE (Simulation Program with Integrated Circuits Emphasis) has created a demand for nonlinear state space averaged SPICE converter models because execution times of brute-force SPICE models are impractical. The theory, evolution, and use of a fast, nonlinear, duo-mode SPICE model of a current-programmed buck converter is described. A slow brute-force SPICE simulation confirmed results obtained from the fast mode View full abstract»

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  • Computer-aided electrical design of power processing systems

    Page(s): 72 - 81
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    A computer-based approach to power supply design is presented and illustrated with a high-power forward converter example. The approach demonstrates a highly effective method of using computers to achieve design optimization while reducing design time and cost. A system-level simulation tool, based on generalized averaged models, is also presented and its use is illustrated with hardware measurements View full abstract»

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  • Magamp post regulators-practical design considerations to allow operation under extreme loading conditions

    Page(s): 368 - 376
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    Practical design equations and guidelines to allow magamp operation under extreme loading conditions are established. Three conditions are considered: shutdown of output, foldback of the output current, and operation under discontinuous-inductor-current mode. Several numerical examples are used to illustrate design considerations and the use of the design equations View full abstract»

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