Ahmad Muhyiddin Yusof
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Preferred name
Ahmad Muhyiddin Yusof
Official Name
Ahmad Muhyiddin, Yusof
Alternative Name
Yusof, Ahmad Muhyiddin
Yusof, Ahmad Muhyiddin Bin
Main Affiliation
Scopus Author ID
58332127000

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The effect of amplitude modulation index on harmonic distortion in unipolar SHEPWM inverter

2021-12-01 , Norhanisa Kimpol , Ahmad Muhyiddin Yusof , Muhammad Zaid Aihsan , Baharuddin Ismail , Mohd Hafiz Arshad , Mohd Saifizi Saidon

The appearance of low order odd harmonic in the AC power line can be mitigated by projecting a proper switching angle during the conversion of the inverter. The switching angles can be obtained by solving the numerical nonlinear equation using numerous solving techniques and algorithms. Several studies shows the value of harmonic significantly increase whenever the amplitude modulation decrease for the SPWM switching scheme of the inverter. However, this topic has not yet covered in the single-phase SHEPWM inverter. This paper is to study the effect of the amplitude modulation index towards the harmonic distortion in the SHEPWM switching technique. To solve the numerical equations, MATLAB code is used to produce the specific switching angles to drive the inverter by solving the numerical equations. The validation of results thru hardware implementation using EZDSPTMS320F28335 to produce the digital signal for controlling the inverter. The targeted low order harmonic to be eliminated are the 3rd, 5th and 7th and three four amplitude modulation indices will be compared and observed in term of total harmonic distortion. The THD results for amplitude modulations 0.6, 0.7, 0.8 and 0.9 are 17.50%, 15.10%, 13.30% and 10.63%.

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Lightning generated electric field over land and sea at northern region of peninsular malaysia: Measuring setup

2020-09-01 , Ahmad Muhyiddin Yusof , Abdul-Malek Z. , Wooi Chin Leong

Lightning electric fields can be characterized based on its origins which include the preliminary breakdown, stepped leader, return stroke, subsequent return stroke, dart leader, dart-stepped leader, narrow bipolar pulses, cloud activity between strokes, regular pulse trains, K and M changes, and chaotic pulse trains. The aim of this work is to describe a lightning measuring setup suitable for characterizing lightning electric fields and their propagation when the measuring sensors are close to the sea. A location close to the sea in Northern Malaysia was identified and prepared for the study. Parallel plate and vertical whip antennas are used as the main sensors, which are connected to a high-speed digital storage oscilloscope through customized analog filter buffer circuits. Noise-distortion effects in the recorded data are filtered using MATLAB computer simulation before further analyses are carried out. The 1-D wavelet technique is used in the signal denoising process. Preliminary results show that the installed setup and denoising method is adequate and potentially efficient for the pre-processing of lightning electric field signals, and hence can be used for the detailed characterization study including the effects of sea on lightning characteristics and propagation.

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Modified Sinusoidal PWM Technique for Low Loss Inverter Application

2021-01-01 , Muhammad Zaid Aihsan , Hariz M.F. , Wan Azani Wan Mustafa , Ahmad Muhyiddin Yusof , Hasliza A Rahim @ Samsuddin , Alkhayyat A.

The efficiency of the main system is the most important concern for all power electronic engineers when designing power electronic converters. Normally there is a high switching state in conventional full-bridge inverter with sinusoidal pulse width modulation (SPWM), resulting in greater switching loss. This problem usually causes the efficiency of the inverter to fall to a certain level, resulting in poor inverter performance. In this study, the switching strategy can be changed to reduce the switching status while maintaining the original inverter frequency. The main goal of this research to reduce the switching loss of the inverter by modified the conventional SPWM to become a lesser switching state without losing the nature characteristic of the SPWM switching technique. The modified SPWM will be compared to the conventional SPWM in terms of switching loss and total harmonic distortion performance.

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Comparative investigations on different types of inductors in single-phase inverter

2021-12-01 , Muhammad Zaid Aihsan , Ahmad Muhyiddin Yusof , Hasliza A Rahim @ Samsuddin , Baharuddin Ismail , Wan Azani Wan Mustafa , Mohd Saifizi Saidon , Muhammad Izuan Fahmi Romli

This article organized in two sections where it compares the performance of single-phase inverters using various types of inductors with differences modulation technique of pulse width modulation (PWM). Not all inductors perform the same function, even the inductance value is the same. The study will investigate the capability of each inductor on its performance to convert the unfiltered AC voltage into filtered sinusoidal AC voltage. The drum core and toroidal core inductors were used in this investigation. For both inductors, the performance will be analyzed based on Bipolar and Unipolar switching schemes in a single unit H-bridge circuit. The validation of results are through experimental assessment only and it will be evaluating the shape of sinusoidal AC voltage and the content of total harmonics distortion in the AC voltage for both inductors.

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