Pulse Width Modulation-A Study

2024-08-28T10:29:40+0530

To fulfill partial power requirements, variable resistance devices such as rheostats were used
to control the current entering a device (i.e., sewing machines). These devices suffered from
major energy losses from heat in the resistor elements. Other device power control devices
included voltage stepping autotransformers such as the Autrastat. There was a need for a low
cost, efficient and compact option for providing adjustable power for electronic devices.
Variable (Switching) power supplies began being used in mass by the military commercial
product designers became curious when seeing the military applications of the switching
power supplies. One of the early applications of Pulse Width Modulation was in the Sinclair
X10, an audio amplifier in the 1960s. In 1976, Bob Mammano (Silicon General) invented the
SG1524 regulating pulse width modulator integrated circuit. Pulse Width Modulation
variable speed drives are increasingly applied in many new industrial applications that
require superior performance. Recently, developments in power electronics and
semiconductor technology have lead improvements in power electronic systems. Hence,
different circuit configurations namely multilevel inverters have become popular and
considerable interest by researcher are given on them. Variable voltage and frequency
supply to A.C drives is invariably obtained from a three-phase voltage source inverter. A
number of Pulse Width Modulation (PWM) schemes are used to obtain variable voltage and
frequency supply. The most widely used PWM schemes for three-phase voltage source
inverters are carrier-based sinusoidal PWM and space vector PWM (SVPWM). There is an
increasing trend of using space vector PWM (SVPWM) because of their easier digital
realization and better dc bus utilization.

Biometrics Recognition

2024-08-28T10:31:24+0530

A wide variety of systems require reliable personal recognition schemes to either confirm or
determine the identity of an individual requesting their services. The purpose of such schemes
is to ensure that the rendered services are accessed only by a legitimate user and not anyone
else. Examples of such applications include secure access to buildings, computer systems,
laptops, cellular phones and ATMs. In the absence of robust personal recognition schemes,
these systems are vulnerable to the wiles of an impostor. Biometric recognition, or simply
biometrics, refers to the automatic recognition of individuals based on their physiological
and/or behavioral characteristics. By using biometrics it is possible to confirm or establish
an individual’s identity based on “who she is”, rather than by “what she possesses” (e.g., an
ID card) or “what she remembers” (e.g., a password)

Journal of Electronic Design Engineering

Pulse Width Modulation-A Study

Biometrics Recognition