Ngah Ramzi Hamzah

Improved switching strategy of single-phase matrix converter as a direct AC-AC converter

This paper presents improved switching strategy sequence of single-phase matrix converter (SPMC) as a direct AC-AC converter modulated by the sinusoidal pulse width modulation (SPWM). The strategy was implemented using MATLAB/Simulink with the SimPower System Block Set. Comparisons with PSPICE are made. The insulated gate bipolar transistor (IGBT) was used for the switching device. New switching control for safe-commutation strategies has been defined and implemented to solve switching transients with sample verification on results.

Single-phase matrix converter operating as buck and boost rectifier

This paper presents the operation of buck and boost rectifier using a single-phase matrix converter topology. Due to symmetrical and bi-directional capabilities the topology is made to operate as buck and boost rectifier. This is facilitated through proper switching control algorithm. The circuit behaviour is confirmed by MATLAB/Simulink simulation results verified experimentally in practical realisation.

Boost rectifier using single-phase matrix converter

A new boost rectifier using single-phase matrix converter topology is presented that could synthesize a greater DC output voltage from a given AC supply voltage. Basic operation on single-phase matrix converter which implements boost operation is outlined. Selected simulations and experimental results are presented.

Safe-commutation strategy for controlled rectifier operation using single-phase matrix converter

This paper proposes an implementation of a new safe-commutation strategy for controlled rectifier operation using single-phase matrix converter (SPMC). The Pulse Width Modulation (PWM) technique was used to calculate the switch duty ratio to synthesize the output. The proposed safecommutation strategies were developed through an arrangement of commutation switches that allows dead time to avoid voltage spikes due to inductive load. Prior to its practical realization a computer simulation model is developed to investigate the behaviour of the SPMC using Matlab/Simulink (MLS) and PSpice. An experimental test-rig was then constructed to verify the operation; incorporated with control electronics, gate drives, and power circuits. The Peripheral Interface Controller (PIC 16F84A) was used for digital control implementation. selected simulations and experimental results are presented to verify proposed operation.

A New Single-Phase Controlled Rectifier using Single-Phase Matrix Converter with Regenerative Capabilities

A new single-phase controlled rectifier using single-phase matrix converter (SPMC) with fully controllable regenerative capabilities is presented. PWM technique was used to calculate the switch duty ratio to synthesize the output. Safe commutation strategy was implemented to avoid voltage spikes due to inductive load. Selected simulation and experimental results are presented to verify proposed operation.

Modeling of electronic transformer design with the implementation of Single-Phase Matrix Converter using MATLAB/Simulink

This paper investigates single-phase electronic transformer design using two stages of Single-Phase Matrix Converter (SPMC) coupled through a high frequency transformer each at the primary and secondary winding in an effort to reduce the size in the future applications of power transformer. Loads are presented in the form of passive device. The proposed system is simulated using MLS with SimPowerSystems environment. An output frequency of 1000 Hz is synthesized on the input stage of the transformer using Pulse Width Modulation (PWM) technique with the output converted by another SPMC that produces 50 Hz output. Commutation strategies are implemented to mitigate associated problems arising from the use of inductive load.

Modelling a Simulation of a new Single-phase to Single-phase Cycloconverter based on Single-phase Matrix Converter Topology with Sinusoidal Pulse Width Modulation Using MATLAB/Simulink

Single-phase Cycloconverters are used for AC-AC power conversion particular for speed control of AC drives. In this work the Single-phase matrix converter (SPMC) topology is used for cycloconverter operation are proposed. IGBTs are used for the power switches. The well-known sinusoidal pulse width modulation (SPWM) scheme is used in this instance. This paper presents work on modelling and simulation of cycloconverter using MATLAB/Simulink incorporating the SimPowerSystem blockset. Simulations are compared with the well-known Pspice simulations to ascertain the accuracy of modelling. Experimental verifications were also carried out to validate the simulation model and the converter.

Performance evaluation on effect of pre-sonication on nanoparticulates during wet nano-milling of drugs

Nano-sizing of drug particle size has been identified as a potentially effective method to increase solubility and hence drug effectiveness. By nanomilling, stable nano-scale particulates can be prepared which have improved physical properties. Nanoparticulates of poorly water-soluble drugs can be prepared by milling of drugs into nano range and achieve optimal stability condition. In this study, effect of pre-sonication followed by wet grinding was assessed on the particle sizes of griseofulvin and ketoconazole in dispersions containing surfactants. The sizes of drugs particulates were reduced to less than 200nm in size with a Polydispersity Index (PDI) below than 1.0 when pre-sonication and nanomilling were applied consecutively.

FPGA Design of Single-phase Matrix Converter Operating as Cycloconverter

This paper is concerned on FPGA design for control implementations of the single-phase matrix converter (SPMQ operating as a cycloconverter. The sinusoidal pulse width modulation (SPWM) technique is used to synthesize the output voltage. The power circuit uses the insulated gate bipolar transistor (IGBT) as switching device in the SPMC implementation. Safe-commutation strategy was incorporated to solve switching transients. A Xilinx field programmable gate array (FPGA) was used at the heart of the control electronics, implemented to verify operation with selected simulation and experimental results presented.

A Study on the Lightning Impulse Breakdown Voltages of Palm Oil and Coconut Oil by Different Methods

In recent years, there have been a number of interests on the Palm Oil (PO) and Coconut Oil (CO) as a potential alternative dielectric insulating fluid in transformers which stimulate different types of studies on these oils properties. Among the important studies is the lightning impulse properties. This paper presents the investigation on the lightning impulse breakdown voltage of PO and CO under non-uniform electric field. The PO used in this study is Refined, Bleached and Deodorized Palm Oil (RBDPO) Olein type. The influence of the testing methods, rising-voltage and up-and-down are investigated at 2 gap distances for both oils. It was found that the lightning breakdown voltage performance for some of the RBDPO and CO are comparable to MO.