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Journal : Indonesian Journal of Electrical Engineering and Computer Science

Nonlinear Servomotor in Single Pulse Simulation of Electrical Discharge Machining System Modeling Hassan Lee; Azli Yahya; Nor Hisham Khamis; Shahrullail Samion
Indonesian Journal of Electrical Engineering and Computer Science Vol 1, No 2: February 2016
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v1.i2.pp319-328

Abstract

Electrical Discharge Machining, EDM is a nonconventional and high precision machining.  EDM system is considered a combination of servo system and EDM process. The servo system precisely controls the gap between electrode and workpiece for the continuous electrical discharges occurrence. Machining performance and stability depend on the performance of servo system. The EDM servo system usually modeled as a linear system, which ignores the nonlinearities of the motor. An assumption that the nonlinearities are insignificant in EDM system model may leads to modeling errors and result in poor control performance. In this study, nonlinear EDM servo system model was presented and the dynamic response of the model was analyzed and compared with the linear model. Simulation result shows a slightly difference in system response and a controller used in linear model is less efficient for a nonlinear EDM servo system model. The results are very useful for control strategy and can contribute to a better machining performance and stability of EDM applications.
Miniaturization of Broadband Wilkinson Power Dividers Nadera Najib; Kok Yeow You; Chia Yew Lee; Mohamad Ngasri Dimon; Nor Hisham Khamis
Indonesian Journal of Electrical Engineering and Computer Science Vol 10, No 1: April 2018
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v10.i1.pp241-247

Abstract

This paper proposed three modified Wilkinson power dividers in order to achieve a size reduction and a wide bandwidth. The first structure presented the power divider using compact folded step impedance transmission lines rather than the uniform microstrip line design for operating center frequency of 3 GHz. The second structure showed the power divider with delta-stub for 2.4 GHz. Finally, the third modified structure introduced the two-section Wilkinson power divider using series-delta stub for center frequency of 2.4 GHz as well. The study managed to get an overall dimension of 15 mm × 9.5 mm for the first proposed design achieving a reduction of 75.6 % and fractional bandwidth of 133 %. For the second proposed structure, the size was 15 mm × 15 mm with a reduction of 56 % and fractional bandwidth of 56 %.  While the third design size was 17 mm × 15 mm with a reduction of 63.6 % and the structure achieved a broadband bandwidth with fractional bandwidth of 220 %.  The proposed power dividers used RT/duroid 5880 substrate with a thickness of 0.38 mm. Simulation and measurement results indicated that the modified power dividers showed equal power division, good phase balance, high isolation between output ports, and good return loss better than -12 dB covering the operating frequency range.