01-10-2012, 04:08 PM
Simulation of Multipulse AC-DC Converters for Medium Voltage ASD’s
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ABSTRACT
This paper presents the simulation of Multipulse Converters for medium voltage Adjustable Speed Drives
(ASD).Multipulse converter compensates the effects of harmonics by using the phase shifted transformer. The
Multipulse configuration consists of several six-pulse converter units in either series or parallel on the DC side.
These units are phase-shifted with respect to each other by the transformer connection. Designs of different
autotransformer for 12, 18, and 24 pulse converters have been presented along with their MATLAB based
simulation. [10, 12]The input current waveform and voltage waveform have been observed and Total Harmonic
Distortion (THD) has been calculated. This approach is different from conventional approach because here
autotransformer is designed by use of several linear transformers.
INTRODUCTION
In modern mechanical/electrical energy conversion the power generating system plays very important role. It
not only facilitates transfer of the mechanical energy into electrical but also conditions the characteristics of the
source in such a manner that the output characteristics are equal to those required by the standards of utility and
the appliances connected into it. Thus it can also serve as an interface between the utility and compensate for
undesirable effects such as: unbalanced loads, nonlinear loads and harmonics. Recently considerable interest has
been focused on the use of Multipulse converter for medium voltage Adjustable speed drive (ASD) or variable
speed drive (VSD) [3, 4]. Many industrial processes such as assembly lines must operate at different speeds for
different products. Using Multipulse converters allows a reduction in the size of the filtering element.
Multipulse converter is a suitable configuration to reach high power rating and high quality output waveform
besides of reasonable dynamic response [2]
RESEARCH METHODOLOGY
The Multipulse Converter theory deals with the reduction of harmonics present on the source side. This theory
involves with the phase shifting of the input voltage and thereby breaking the input voltage into number of
pulses. As the pulse number increases, the harmonics present in the input decreases and the Total Harmonic
Distortion (THD) reduces. The use of 6 pulse diode bridge rectifier is the integral part of this system. The main
consideration is the design of phase shifting transformer for different pulse configurations, as the pulse number
increases the designing becomes more and more complex .This paper present the simplified scheme of
designing phase shifting transformer by the use of linear transformers.