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Power Electronics Letters, IEEE

Issue 4 • Date Dec. 2005

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Displaying Results 1 - 15 of 15
  • Table of contents

    Page(s): c1
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  • IEEE Power Electronics Letters publication information

    Page(s): c2
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  • Single-phase Z-source PWM AC-AC converters

    Page(s): 121 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    The letter proposes a new family of simple topologies of single-phase PWM ac-ac converters with a minimal number of switches: voltage-fed Z-source converter and current-fed Z-source converter. By PWM duty-ratio control, they become "solid-state transformers" with a continuously variable turns ratio. All the proposed ac-ac converters in this paper employ only two switches. Compared to the existing PWM ac-ac converter circuits, they have unique features: providing a larger range of output ac voltage with buck-boost, reversing or maintaining phase angle, reducing in-rush and harmonic current, and improving reliability. The operating principle and control method of the proposed topologies are presented. Analysis, simulation, and experimental results are given using the voltage-fed Z-source ac-ac converter as an example. The analysis can be easily extended to other converters of the proposed family. The proposed converters could be used in voltage regulation, power regulation, and so on. View full abstract»

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  • Thermal design based on surface temperature mapping

    Page(s): 125 - 129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB) |  | HTML iconHTML  

    A method of extracting a conservative thermal model from an existing PCB assembled converter is investigated. This improves upon thermal management by increasing the thermal management contribution of the PCB itself. A thermal calibration loop is proposed in which a given converter is analyzed and data extracted, in order to create a thermal map of the surface temperature from which the component layout and thermal profiles can be estimated. Thermal figures of merit are vital to quantify the thermal adjustments, recorded in this thermal map, which are required during thermal calibration. The thermal figures of merit are also flexible enough to allow for specific optimization objectives such as high power density, or overall reliability. Two graphical means to predict temperature profiles required in the thermal calibration loop have been investigated: a thermal resistor network method with a purely analytical approach, suitable for relatively small systems where the geometry and loss analysis are simple (fewer than ten components), or a more elaborate method using a finite difference method algorithm, implemented in a spreadsheet environment. Both provide flexible means for PCB thermal layout and provide straightforward graphical visualization. A case study illustrates the complete design method. View full abstract»

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  • Implementation of pulse-width-modulation based sliding mode controller for boost converters

    Page(s): 130 - 135
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    This letter addresses the various issues concerning the implementation of a pulse-width modulation (PWM) based sliding mode (SM) controller for boost converters. The methods of modeling the system and translation of the SM control equations for the PWM implementation are illustrated. It is shown that the control technique is easily realized with simple analog circuitries. Various experiments are conducted to test the static and dynamic performances of the system. View full abstract»

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  • Modeling of capacitor impedance in switching converters

    Page(s): 136 - 140
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Switched capacitor (SC) converters are gaining acceptance as alternatives to traditional, inductor-based switching power converters. Proper design of SC converters requires an understanding of all loss sources and their impacts on circuit operation. In the present work, an equivalent resistance method is developed for analysis, and equivalent resistance formulae are presented for various modes of operation. Quasiresonant converters are explored and compared to standard SC converters. Comparisons to inductor-based switching power converters are made. A number of capacitor technologies are evaluated and compared for applications to both SC converters and inductor-based converters. The resulting model can be used to accurately predict and optimize converter performance in the design phase. View full abstract»

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  • A passive auxiliary circuit achieves zero-voltage-switching in full-bridge converter over entire conversion range

    Page(s): 141 - 143
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    A passive auxiliary circuit is proposed to achieve zero-voltage-switching (ZVS) over the entire conversion range in a full-bridge (FB) pulse-width modulated (PWM) converter (FBZVS converter) with minimum conduction loss penalty. The stored energy in the auxiliary circuit is minimal under the full-load condition. It increases progressively as the load current decreases. The proposed auxiliary circuit is passive, simple and can be viewed as an add-on to the conventional FBZVS converter. The principle of operation is described and the performance is demonstrated on a 100 kHz, 500 W prototype. View full abstract»

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  • Interpreting small signal behavior of the synchronous buck converter at light load

    Page(s): 144 - 147
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB) |  | HTML iconHTML  

    The pulse-width-modulation (PWM) buck converter with synchronous rectifiers operating at light load is usually modeled by its continuous conduction mode (CCM) model. However, the actual power-stage small-signal control-to-output response shows a different behavior from what the traditional CCM model predicts, specifically, more damping around the double-pole frequency, instead of more resonance. This paper presents a modified small-signal light-load model for a synchronous buck converter. The developed model accurately predicts the actual small-signal behavior of a PWM converter at light load. The derived averaged switch model for light load can also be used for the small-signal models of the other basic PWM converters operating in CCM at light load. View full abstract»

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  • Synthetic-ripple modulator for synchronous buck converter

    Page(s): 148 - 151
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    Comprising a hysteretic comparator and a ripple synthesizer, the synthetic-ripple modulator (SRM) allows voltage-hysteretic modulation to be realized in low-voltage buck converters where the natural voltage ripple is too small for reliable hysteretic operation. Circuit implementation, steady-state operation, and design equations are described for an SRM controlling a buck dc-dc converter. The basics are verified experimentally by a buck converter switched at 420 kHz and delivering 10 A at 1.8 V. View full abstract»

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  • IEEE Power Electronics Letters Information for authors

    Page(s): 153 - 154
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  • 2005 Index

    Page(s): 155 - 159
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  • Order form for reprints

    Page(s): 160
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  • IEEE Power Electronics Society Information

    Page(s): c3
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  • IEEE Power Electronics Letters blank page

    Page(s): c4
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