International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 3 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
Reduction of Total Harmonic Distortion using Multipulse Cycloconverter Jinesh Derawala, Rushang Parekh, Abin Thomas, Krunal Shah Jinesh Derawala: Student, Electrical Engineering, SRICT, Gujarat, India Rushang Parekh: Student, Electrical Engineering, SRICT, Gujarat, India Abin Thomas: Student, Electrical Engineering, SRICT, Gujarat, India Krunal Shah: Professor, Electrical Engineering, SRICT, Gujarat, India ----------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The need for use of cycloconverter (AC to AC
1.1 History of Cycloconverter
converters) is in controlling a.c motors at low speed drive especially in high power application. When designing such type of converters, output will be having the problem of power quality. Hence to improve power quality and reduce the total harmonic distortion to specific standards pulse numbers should be increased. The project includes the MATLAB/SIMULINK model of cycloconverter on different pulses. Pulse number will increase to reduce total harmonic distortion. Comparison will be made after completing the simulation process. The control strategy of supplying the firing pulses is based on the cosine wave crossing method. The MATLAB/SIMULINK model for the control circuits to perform the procedure of this strategy will be constructed. The cycloconverter will operate satisfactory having either number of pulses. By Increasing number of pulses of cycloconverter will rectify the output waveforms of cycloconverter and will nullify the harmonic effect, which result in improvement in output power factor. good agreement with them, which indicates that the system is reliable.
A device which convert input power a one frequency to output power at different frequency is called as cycloconverter. The basics of this converters were proposed by Hazeltine in 1926 and first cycloconverter was built in 1930s using mercury arc valves for converting standard 50Hz supply to single-phase 16.66Hz supply for use in ac traction system in Germany. Nowadays Cycloconverter used in large-power-low-speed variable voltage variable-frequency ac drive in cement and steel rolling mills as well as in variable-speed constantfrequency system in aircraft and naval ships.
(Symbol of Cycloconverter)
1.2 Types of Cycloconverter
KeyWords:
MULTIPULSE CYCLOCONVERTER, MATLAB/SIMULINK, TOTAL HARMONIC DISTORTION, POWER QUALITY, AC TO AC CONVERTER
1.2.1 Step-up cycloconverter: The output frequency (fo) is more than the supply frequency (fs). 1.2.2 Step-down cycloconverter: The output frequency(fo) is lower than than the supply frequency (fs).
1.INTRODUCTION
1.3 Operating Principle
An electrical drive which consists of electric motors. Now a day in modern electric drive system power electronic converters are used as power controller. In drives system, it consists of two types: (a) AC drives and (b) DC drives.
1.3.1 Single-phase to Single-phase Cycloconverter Introduction of operation principles of cycloconverter should be started with single-phase to single-phase cycloconverter. Cyclo-converter are two inversely connected rectifiers. Suppose for getting ¼ of input voltage at the output, for the 1st two cycles of Vs the positive converter operates, supplying current to the load and it will rectify the input voltage. In the next two cycles the negative converter operates supplying current in the inverse direction. When any one of the converters operates, the either is disabled, so that there is no current flowing between both the rectifiers. In the above figure, Vs represents input supply voltage and Vo is the required output voltage which is ¼ of supply voltage.
For the Application purpose, AC drives are widely used for adjustable speed control, frequent starting, better speed regulation, braking and reversing. And the DC drives are also used for some important application such as paper mills, mine winders, hoists, elevators, printing presses, traction, textile mills, machine tools, cranes and rolling mills. For the industrial applications development of high performance motor drives are very essential. AC drives are less costly and less complex as compared to the DC drives, so it is widely used in industrial applications.
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