TO control the speed of DC Motor Simple Project

SPEED CONTROL OF DC MOTOR

PRESENTED BY:

MUQADSA IFTIKHAR CLASS NO. 03 REG. NO (09ABELT0290)

ZUNAIB ALI CLASS NO. 09 REG. NO (09ABELT0296)

Supervised BY:

ENGR. SANIA SAEED

ABSTRACT

• The purpose of a motor speed control is to

take a signal representing the demanded

speed and drive the motor at that speed.

INTRODUCTIONThe speed of dc motor is directly proportional to the

supply voltage, if we reduce the supply voltage from 12V

to 6V, the motor will run at half the speed.

SCR “phase-angle controlled” drive -By changing the

firing angle, variable DC output voltage can be obtained.

Here we are using microcontroller applications. For this

we are using AT89C51 IC and by using this we are setting

the speed of motor.

MAIN COMPONENTS1. 220 V , 50Hz AC Supply

2. Step Down Transformer

3. DC motor

4. Micro controller

5. Thyristor (SCR)

6. NPN Transistor

7. Crystal Oscillator (11.0592MHz)

8. 5V DC Supply

DC MOTOR

The  DC motor is electric motor that runs on direct current

electrically.

DC motor works based on the LORENTZ FORCE.

In DC motor voltage is proportional to speed

ADVANTAGES

Low initial cost

High reliability

Simple control of motor speed

Block Diagram

Zero Crossing Detector

0 20 9ms 18ms

tt

0

2

0

9ms

18ms

t

t

t20 3

Sinusoidal input

Zero Detector Output

Micro- Controller AT89c51 A smaller computer

On-chip RAM, ROM, I/O ports.

RAM ROM

I/O Port

TimerSerial COM Port

Microcontroller

CPU

A single chip

CIRCUIT DIAGRAM

AT89C51 Programming:#include <reg51.h>

unsigned char x, y;sbit driv = P2^2;

void main(){

P1=255;P2=0x00;IE=0x81;

while(1){switch (P1){

case 0:x=0xFF;y=0xFF;break;

case 1:x=0x66;y=0xFC;break;

case 2:x=0xCC;y=0xF8;break;

case 3:x=0x33;y=0xF5;break;

case 4:x=0x99;y=0xF1;break;

case 5:x=0xFF;y=0xED;break;

case 6:x=0x66;y=0xEA;break;

case 7:x=0xCC;y=0xE6;break;

case 8:x=0x32;y=0xE3;break;

case 9:x=0x99;y=0xDF;break;

} } }

void External0(void) interrupt 0

{ driv =0;TMOD=0x10;TL1=x;TH1=y;TR1=1;

Continue…

while(TF1==0);

TR1=0;TF1=0;driv=1;

TMOD=0x01;TL0=0xCC;TH0=0xF8;TR0=1;

while(TF0==0);TR0=0;TF0=0;driv=0;

}

Continue…

Explanation: Input 220V, 50Hz is step down to 30V,

50Hz.

This 30V, 50Hz is applied to

Controlled HWR with DC motor as

load.

For the gating circuitry the same

input 30V, 50Hz is applied to zero

crossing detector to generate an

external interrupt.

Logic states are used to provide

firing angle α.

When the external interrupt occurs

micro-controller generates pulse

according to provided α.

Outputs for Different Firing Angle:

Voltage Across Motor HWR Rectifier Output

For α = 0

Continue…

Voltage Across Motor HWR Rectifier Output

For α = 7ms

Continue…

Voltage Across Motor HWR Rectifier Output

For α = 3ms

Software Simulation:

Extension of Our Project

BRIDGERECTIFER

FILTER

5V REGULATOR

12V REGULATOR MOTOR

MOSFET

SENSORCOMPARATOR

+5V+5V

GNDGND

MICROCONTROLLERLCD16X2

+5V

+5VGND

GND

RSRWEN

D4D5D6D7

TRANSFORMER

UP_SWUP_SW

ApplicationsROBOTIC CONTROLS.SWING MACHINES.ELECTRONIC BIKES.WINDING MACHINES.DC OPERATED DRILL MACHINES.MOBILE AIR CONDITION FANS.TOYS.ELCTRONIC DOOR CONTROLLERS. ELECTRONIC CHAIRS (beauty parlor etc.)

CONCLUSIONWe have achieved the required speed and

thyristor is a very good device for obtaining the variable DC there by controlling the motor speed.

This circuit is just a basic circuit for understanding DC motor speed control. In case of HWR we got zero voltage in negative half cycle that’s why has power efficiency.

Any query