As the voltage and current ratings and switching
characteristics of power semiconductor devices keep
improving, the range of applications continues to
expand in areas such as lamp controls, power supplies
to motion control, factory automation, transportation,
energy storage and electric power transmission and
distribution.
The technological advances made in the field of power
semiconductor devices over the last two decades, have
led to the development of power semiconductor
devices with high power ratings and very good
switching performances. Some of the popular power
semiconductor devices available in the market today
include Power MOS Field Effect Transistors (Power
MOSFETs), Insulated Gate Bipolar Transistors
(IGBTs) and Gate Turn off Thyristors (GTOs).
Three-phase voltage source inverters are widely used
in variable speed ac motor drives applications since
they provide variable voltage and variable frequency
output through pulse width modulation control.
Continuous improvement in terms of cost and high
switching frequency of power semiconductor devices
and development of machine control algorithm leads
to growing interest in more precise PWM techniques.
The most widely used PWM method is the
carrier-based sine-triangle PWM method due to
simple implementation in both analog and digital
realization.
On the other hand, the main advantages of modern
power electronic converters, such as high efficiency,
low weight, small dimensions, fast operation, and
high power densities, are being achieved through the
use of the so-called switch mode operation, in which