Speed control of dc motor by switch mode power supply (smps)
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Date
2015
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Publisher
UMT.Lahore
Abstract
This thesis gives the whole idea and theme of the ''Speed Control of DC Motor by
SMPS" to the reader. Switch Mode Power Converter (SMPS) is an efficient and
commonly use power converter nowadays. Today, two types of DC power supply can
be found in the market, Switch-Mode Power Supply (SMPS) and linear power supply.
However, many customers prefer to choose SMPS than linear power supply because for
same power rating, SMPS is smaller, cheaper and lighter than linear power supply.
SMPS also have better efficiency than linear power supply. In this thesis an AC to DC
converter SMPS circuit, having a BJT's tor switching operation and a PWM based
feedback circuit for driving the switching of the BJT's. For an ideal switch, all power is
absorbed by the load, and the energy efficiency is 100%, because when the switch is
open, there is no current in it; when the switch is closed, there is no voltage across it.
For this project, PWM (Pulse Width Modulation) is being used to drive the switches.
This project is focusing on developing SMPS using fly-back converter topology. In this
design the line voltage at 220V/50Hz is taken as input. An Isolation Transformer is used
to isolate the DC output from input supply. The transformer output is rectified by the
high frequency Diode bridge rectifier and is filtered using a capacitor to give the
regulated DC output. A Voltage regulator is connected to give the precise voltage
output. This regulated voltage is driven by PWM feedback signal, to control the output
voltage level. The dc voltage at the output depends on the width of the switching pulse.
The on and off of the switch is important because the duty cycles of the PWM is used to
regulate the DC output voltage. So the desire output voltage can be produced by
generate various duty cycl