Pongswatd, Sawai

Preferred name

Pongswatd, Sawai

Alternative Name

Pongswatd, S.

Main Affiliation

School of Engineering

sawai.po@kmitl.ac.th

Now showing 1 - 10 of 30

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Design of a multiple-input parallel SC DC-DC converter and its efficiencyestimation method
(2009-09-01)
Eguchi, Kei
;
Sugimura, Tatsuya
;
Pongswatd, Sawai
;
Tirasesth, Kitti
;
Sasaki, Hirofumi
A multiple-input parallel SC (Switched Capacitor) DC-DC converter and itsefficiency estimation method are proposed in this paper. The proposed parallelconverter consists of two different kinds of converter blocks: 1. a 1.5×step-up SC DC-DC converter employing an input voltage from a lithium battery and2. a novel step-up converter employing an input voltage from clean energysupplies. Since the proposed step-up converter can achieve not only a largestep-up conversion ratio but also a wide input range, the proposed parallelconverter enables us to extend battery runtime, reduction of heat, and so on.Furthermore, concerning the proposed converter, theoretical analyses areperformed to estimate power efficiency. The proposed analysis technique can beextended to the circuit design of other SC DC-DC converters. The validity ofcircuit design and theoretical formulas is confirmed by SPICE simulations.ICIC International © 2009.
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Design of 5x step-up sc dc-dc converter for industrial wireless transmitter
(2011-08-01)
Pongswatd, Sawai
;
Kunsri-U-Chane, Kachane
;
Smerpituk, Krit
;
Eguchi, Kei
;
Sasaki, Hirofumi
In this paper, a 5x step-up switched-capacitor (SC) DC-DC converter utilizing solar energy for industrial wireless transmitters is presented. A wireless transmitter can be supplied by its internal battery in combination with the proposed converter for long battery runtime. A Rosemount wireless transmitter from Emerson Process Management Company is used as a target application example in process measurement. The proposed converter is designed for receiving 1.5 V solar cells and powering 7.5 V connected in parallel with wireless transmitter battery. The validity of circuit design is conrmed by theoretical analysis and SPICE simulation. The derived formulas will be helpful to estimate circuit characteristics. Moreover, SPICE simulation values agree well with theoretical results.
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Parallel 5x step-up SC DC-DC converter for power efficiency improvement
(2011-01-01)
Pongswatd, Sawai
;
Smerpituk, Krit
;
Eguchi, Kei
;
Sasaki, Hirofumi
In switched-capacitor converter, the fluctuation of on-resistance effects power efficiency in proportion to the decrease of output load. This paper presents switched-capacitor (SC) DC-DC converter that parallel-connected to improve the power efficiency. The converter utilizes solar energy for industrial wireless transmitter. It can be supplied by its internal battery in combination with the proposed converter for long battery runtime. A Rosemount wireless transmitter from Emerson Process Management Company is used as a target application example in process measurement. The proposed converter is designed for receiving 1.5 V solar cells and powering 7.5 V connect in parallel with wireless transmitter battery. The validity of the theoretical analyses is confirmed by SPICE simulations and experimental results. The derived formulas will be helpful to estimate circuit characteristics. Moreover, SPICE simulation values and experimental results agree well with theoretical results. © 2011 SICE.
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Parallel-connected high voltage multiplier with symmetrical structure
(2014-01-01)
Eguchi, Kei
;
Pongswatd, Sawai
;
Terada, Shinya
;
Oota, Ichirou
A high voltage multiplier is proposed for non-thermal food processing systems utilizing an underwater shockwave. Unlike conventional Cockcroft-Walton Voltage Multiplier (CWVM) providing a DC output from an AC input, the proposed multiplier consists of two switched-capacitorbased DC-DC converters with different polarities. Owing to the symmetrical bipolar structure without magnetic component, the proposed multiplier can achieve faster response speed and lower voltage drop than the conventional CWVM. The theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulations show the effectiveness of the proposed voltage multiplier. © (2014) Trans Tech Publications, Switzerland.
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Design of a switched-capacitor-based serial DC-DC converter using clean energy power supplies
(2010-07-30)
Eguchi, Kei
;
Pongswatd, Sawai
;
Sugimura, Tatsuya
;
Thepmanee, Teerawat
;
Tirasesth, Kitti
For mobile back-lighting applications, a switched-capacitor-based serial DC-DC converter using solar power supplies is proposed in this paper. Unlike conventional switched-capacitor DC-DC converters, the proposed converter pushes up the output voltage of a switched-capacitor-based circuit by the voltage of solar cells. For this reason, the proposed converter can realize not only long battery runtime but also small hardware-cost and wide input-range. Concretely, in comparison with the conventional parallel converter using 1.5× step-up SC converters, the proposed converter can achieve 20% reduction of hardware cost and 16% extension of input range. The characteristics of the proposed converter are clarified by theoretical analyses. Furthermore, SPICE simulations and experiments show the validity of circuit design, where theoretical results correspond well with simulation results.
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Design of a dual-input SC DC-DC converter realizing negative outputs
(2011-01-01)
Eguchi, Kei
;
Pongswatd, Sawai
;
Tirasesth, Kitti
;
Sasaki, Hirofumi
;
Zhu, Hongbing
Aimed at a back-lighting application, a dual-input switched-capacitor (SC) DC-DC converter with battery charge process is proposed in this paper. The proposed converter can realize -1/N× (N = 2,3,.) step-down conversion as well as (N + 1)/N× step-up conversion. By converting clean energy such as solar energy, the proposed dual-input converter not only drives light-emitting diodes (LEDs) but also recharges the battery, although conventional single-input converter only consumes battery energy. In the proposed converter, the -1/N× stepped-down voltage is generated to drive the LED's cathode when the input voltage is insufficient to drive a 1× transfer mode. Furthermore, unlike conventional converters, the battery is charged by the (N + 1)/N× stepped-up voltage when the LED back light is in standby mode. Hence, the proposed converter can realize long battery run time. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments. The derived theoretical formulas will be helpful to estimate circuit characteristics, because the theoretical results correspond well with the simulation program with integrated circuit emphasis (SPICE) simulation results. © 2011 Institute of Electrical Engineers of Japan.
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Design of step up and down Bi-directional switched capacitor DC-DC converter
(2012-02-01)
Pongswatd, Sawai
;
Smerpituk, Krit
;
Eguchi, Kei
;
Sasaki, Hirofumi
This paper presents the design technique to implement a DC-DC converter that can convert input voltage with step-up or step-down, and bi-directional power flow. The conversion ratio and power efficiency of the converter can be specified by circuit structure, which has capacitors connected in parallel or series configuration. The conversion ratios of step up and step down are 2x, 3x, 4x,... and 1/2x, 1/3x, 1/4x,..., respectively. The direction of power flow can be controlled by state of input and output switches. SPICE simulation results show that output voltage and power efficiency of the proposed converter agree well with theoretical values. © 2012 ICIC International.
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Modeling uncertainties in DC-DC converters with MAtLab® and PLECS®
(2018-11-07)
Asadi, Farzin
;
Pongswatd, Sawai
;
Eguchi, Kei
;
Trung, Ngo Lam
Modeling is the process of formulating a mathematical description of the system. A model, no matter how detailed, is never a completely accurate representation of a real physical system. A mathematical model is always just an approximation of the true, physical reality of the system dynamics. Uncertainty refers to the differences or errors between model and real systems and whatever methodology is used to present these errors will be called an uncertainty model. Successful robust control-system design would depend on, to a certain extent, an appropriate description of the perturbation considered. Modeling the uncertainties in the switch mode DC-DC converters is an important step in designing robust controllers. This book studies different techniques which can be used to extract the uncertain model of DC-DC converters. Once the uncertain model is extracted, robust control techniques such as H<inf>1</inf> and µ synthesis can be used to design the robust controller. The book composed of two case studies. The first one is a buck converter and the second one is a Zeta converter. MATLAB<sup>®</sup> programming is used extensively throughout the book. Some sections use PLECS<sup>®</sup> as well. This book is intended to be guide for both academicians and practicing engineers.
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Design of a hybrid input charge-pump using micropower thermoelectric generators
(2011-08-12)
Eguchi, Kei
;
Pongswatd, Sawai
For industrial wireless transmitters, a hybrid input charge-pump utilizing thermoelectric energy from waste heat is proposed in this paper. Unlike conventional inductor-based converters, the proposed capacitor-based converter supplies energy to a wireless transmitter by using thermoelectric power source in combination with rechargeable battery source. Through theoretical analyses, simulations and experiments, the following results are shown: 1. Even if the voltage of TEG is small, the proposed converter can provide the sufficient voltage to power a wireless transmitter by compensating the insufficient voltage of TEG with the battery voltage. 2. The formulas obtained by the theoretical analyses are useful for designing the proposed converter, because the theoretical results agreed well with the simulation results. 3. The proposed converter is implementable onto an IC chip, because the layout design of the proposed converter is shown. © 2011 IEEE.
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A multiple-input SC DC-DC converter with battery charge process
(2009-12-01)
Eguchi, Kei
;
Pongswatd, Sawai
;
Zhu, Hongbing
;
Tirasesth, Kitti
;
Sasaki, Hirofumi
Aimed at a backlighting application, a multiple-input switched-capacitor (SC) DC-DC converter with battery charge process is proposed in this paper. Unlike conventional SC power converters such as a Dickson-type converter, etc., the proposed converter drives some LEDs by converting energy from solar cells when solar cells offer enough energy. Furthermore, the proposed converter can charge a lithium battery when an output load is light. Hence, the proposed converter enables us to realize long battery runtime. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments. The derived theoretical formulas will be helpful to estimate circuit characteristics, because theoretical results agree well with SPICE simulation results. © 2009 IEEE.

Pongswatd, Sawai

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