speed control of dc motor using triac
DESCRIPTION
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SPEED CONTROL OF DC MOTOR USING TRIAC
V.Narendra,III year,EEE BranchSVCN.
INTRODUCTION
DC motors are widely used in industry because of its low cost, less complex control structure and wide range of speed and torqueWith the the increasing use of power
semicondutor units, the speed control of DC motor is increasingly getting sophisticated and precise.
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 with respect t0 terminal MT1.
To successfully trigger a triac,gate current must come from the main terminal 2(MT2) side of the circuit.
CIRCUIT SYMBOL
SPEED CONTROLThe three methods of speed control
are
Armature voltage controlled
Armature resistance controlled
Flux controlled
ARMATURE VOLTAGE CONTROLThe output delivered by the motor(speed)
decreases with decrease in applied voltage
BLOCK DIAGRAM
OUTPUT WAVEFORMS
COMPONENTSDc motor
Triac
Diac
Capacitors- C1,C2,C3,C4(1F)
Resistors- R1-180Ω,
R2-68k,
R3-47K,
ADVANTAGESIn 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
DISADVANTGESToday 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
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