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 16

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The technique to generate firing signal of converter for linear DC output
(2008-12-01)
Thepmanee, Teerawat
;
Pongswatd, Sawai
;
Ukakimapurn, Prapart
;
Tirasesth, Kitti
The firing angle adjustment of ac-dc converter that adjust firing angle proportional to control signal. The dc output voltage is not linear. This paper presents the technique to generate the firing signal for ac-dc converter which has linear dc output voltage. This technique decoded the arccosine value as binary data and save in ROM, before compare with control signal. All digital circuits and ROM were constructed using Field Programmable Gate Array (FPGA) and Verilog Hardware Description Language (Verilog HDL) so that the proposed technique has small size and ease of implementation. The experimental results show the dc output voltage and output waveform that agree with the design. Moreover, this technique can be applied to multi-output for dual converter and 3- phase system. © 2008 SICE.
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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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Isolated current feedback control for buck converter
(2005-01-01)
Arayawat, Somjai
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Pongswatd, Sawai
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Ukakimapurn, Prapart
;
Trisuwannawat, Thanit
This paper proposes the design and technique for controlling DC voltage of DC-DC converter using isolated current feedback. When testing with different loads [1], the output obtained has good voltage regulator, a wide input voltage range, quick response and safe. This research uses phototransistor to detect output current signal and send feedback with isolated electrical signal to PWM (Pulse Width Modulation) circuit to control the duty cycle fed to switch. Buck converter is a step down voltage converter, which results in the current at output higher than that of input [2]. This research uses output current fed through Opto and select only linear interval current ratio fed to control and feedback. The experiment is performed using Buck-Type DC-DC converter to level the output voltage as desired. Results are satisfying and a simplest circuit. © 2005 IEEE.
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Application of GD3 in value engineering for plastic-part design
(2008-12-01)
Thepmanee, Teerawat
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Sirilappanich, Surachet
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Pongswatd, Sawai
;
Ukakimaparn, Prapart
This paper presents the technique in way engineering value that comes to apply for designing of product plastic. The technique analyzes the data of designing by GD<sup>3</sup> and measures defensive problem in advance of engineering value. Consequently, the technique can prevent the problem and control the designing relate to engineering value before build a mold for product. For acquire knowledge give with the work and can design the product that can have picture stability. Moreover, This technique can decrease material loss, time operation and inventory.
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A technique for mechanical adjustment of DC motor by virtual model
(2007-12-01)
Smerpitak, Krit
;
Naruvorn, Natarak
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Pongswatd, Sawai
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Ukakimapurn, Prapart
This paper presents a technique to adjust and improve mechanical responses of DC Motor. The proposed technique uses math model for simulation to observe the transience and steady state response in no-load condition. Information derived from the simulation results can be applied to compensate the mechanical loss, inertia, viscous friction by feeding electrical energy. The test results of the compensation technique in this research can adjust and improve the response of speed and torque under reasonable tests. Moreover, this technique can apply to virtual load for Dynamometer. © ICROS.
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A voltage/current controlled oscillator using OTAs and RS flip flop
(2008-12-01)
Pongswatd, Sawai
;
Julsereewong, Amphawan
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Tirasesth, Kitti
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Sasaki, Hirofumi
;
Shi, Yan
This paper presents an electronic oscillator specially designed to be controlled in oscillation frequency by the control voltage and external bias current signals. The realization technique is simple and inexpensive based on the use of commercial available devices. The proposed circuit consists of operational transconductance amplifiers (OTAs) and an RS Flip Flop to generate tunable sawtooth and square waves. Experimental results verifying the performances of the proposed circuit are in close agreement with the expected values. An application example showing the usefulness of the proposed voltage controlled oscillator in phase-locked loop frequency synthesizer is also introduced. © 2008 SICE.
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Buck converter controlled by using variable switching frequency technique
(2008-12-01)
Julsereewong, A.
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Pongswatd, S.
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Julsereewong, P.
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Tirasesth, K.
;
Sasaki, H.
In this paper, a linearly tunable voltage controlled oscillator with negatively proportional characteristic, termed VCO, is described. Using the VCO and analog PI controller in feedback path of a buck converter operating in continuous condition mode, a control technique with variable switching frequency is presented. No filtering capacitor is required in the proposed technique that provides the advantage of a simple and compact structure. Experimental results show that the output voltage ripple can be reduced. The output voltage regulation can be also kept in constant without stability problems. © 2008 IEEE.
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A multiple-input SC DC-DC converter with battery charge process
(2009-12-01)
Eguchi, Kei
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Pongswatd, Sawai
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Zhu, Hongbing
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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.
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Synthesis and analysis of a multiple-input parallel SC DC-DC converter
(2009-10-22)
Eguchi, Kei
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Pongswatd, Sawai
;
Tirasesth, Kitti
;
Sasaki, Hirofumi
As compared with parallel converters employing buck converters or boost converters, the analysis of multiple-input parallel switched-capacitor (SC) DC-DC converters is not sufficient. In this paper, a multiple-input parallel DC-DC converter designed by using SC techniques is proposed for mobile back-lighting applications, and handy theoretical formulas are given concerning the power efficiency and equivalent circuit. The proposed parallel converter consists of two different kinds of converter blocks: 1. a 1.5x step-up SC DC-DC converter employing an input voltage from a lithium battery and 2. a novel step-up converter employing an input voltage from solar cells. The proposed converter can offer the output voltage for display back-lighting from solar energy, because the proposed step-up converter can achieve not only a large step-up conversion ratio but also a wide input range. Hence, the proposed converter will enable us to realize a long battery life, reduction of heat, and so on. Furthermore, derived theoretical formulas will be helpful to estimate circuit characteristics, because theoretical results agree well with SPICE simulation results. The validity of circuit design is confirmed by simulations and experiments. ©2009 IEEE.
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Digital technique to generate variable and multiple PWM signals
(2007-01-01)
Pongswatd, Sawai
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Chaikla, Amphawan
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Ukakimapurn, Prapart
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Tirasesth, Kitti
In this paper, we present a digital technique to generate Pulse Width Modulation (PWM) signal using counters, comparators, and latching circuits implemented by Verilog HDL program based on FPGA. The proposed technique can simultaneously generate variable and multiple PWM outputs with parallel processing. Setting each reference-input signal can independently and easily vary the pulse width of each generated signal. The FPGA-based implementation can minimize the size of hardware. The communication can be easily done via a personnel computer. Application example in the design of the proposed technique as the parallel processing is also included. © 2007 IEEE.

Pongswatd, Sawai

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