dc speed motor control.ppt

SPEED CONTROL OF DC MOTOR USING TRIAC

Submitted By :- Ankit Patel

Branch :- EN-3rd Year

Guided by :- Assistant professor:-Mr. Sanjay Kumar

Outline

Background Formulae Methods of speed control TRIAC Circuit Symbol Components used Advantages Disadvantages

INTRODUCTION

DC motors are widely used in industry because of its low cost, less complex control structure and wide range of speed and torque

With the the increasing use of power semicondutor units, the speed control of DC motor is increasingly getting sophisticated and precise.

Formulae

METHODS OF SPEED CONTROL

Practically, speed control of DC motors can be fulfilled using on of two methods Field Control :- by varying the field current. This can be achieved by varying the field voltage. Voltage control :- by varying the armature terminal voltage.

TRIACA triac is a bidirectional thyristor with

three terminals

Its three terminals are designated as MT1(main terminal 1),MT2 & gate by G

Triac can be turned on in each half cycle of the applied voltage by applying a positive or negative voltage to the gate w.r.t terminal MT1

To successfully trigger a triac,gate current must come from the main terminal 2(MT2) side of the circuit

CIRCUIT SYMBOL

BT136

Block Diagram of Speed Contol of DC Motor

D.C.Motor

TRIAC D.C. Supply

COMPONENTS

Dc motor Triac Diac Capacitors- C1 , C2 , C3 , C4-.1F Resistors- R1-180,R2-68, R3-47K,Pot-220k

Description

Waveform

ADVANTAGES……

In earlier days speed of the dc motor was controlled using resistor which resulted in power loss but introduction of triac eliminated the power loss

Armature voltage control method gives good speed regulation and high efficiency

Gives a large speed range with any desired number of speed points

Disadvantages..…..

Today Introduction of IGBT made the speed control of dc motor more feasible

Commutation circuit used in the circuit makes speed control less precise

Thank you!