2. Abstract+ List of Figures+ List of Tables

7/30/2019 2. Abstract+ List of Figures+ List of Tables

1/4

ABSTRACT

DC MOTOR SPEED AND DIRECTION CONTROL

USING PWM AND BRIDGE

A pulse width modulator (PWM) is a device that may be used as an efficient

DC motor speed controller or light dimmer. The project is a versatile device that can

control DC devices which draw up to a few amps of current. The circuit may be used

either 12 or 24 volt systems with only a few minor writing changes .The device has been

used to control the speed and direction the of the DC motor .

A PWM circuit works by making a square wave with a variable on-to-off

ratio, the average on time may be varied from 0 to 100 percent. In this manner a variable

amount of power is transferred to the load.

The main advantage of a PWM circuit over a resistive power controller is the

efficiency, at a 50% level, the PWM will the use about 50% of full power, almost all of

which is transferred to the load, a resistive controller at 50% load power would consume

about 71% of full power, 50% of the power goes to the load and the other 21%is wasted

heating the series resistor.

One additional advantage of pulse reach the full supply voltage and willproduce more torque in a motor by being able to overcome the internal motor resistance

more easily. Two push-to-on switches are provided for increasing/decreasing the speed of

the motor.

Two more push-to-on switches ate provided to rotate the motor in Clock wise

/ Counter clock wise direction.16X2 LCD is connected to display the speed level of the

motor and the direction. LED indication is also provided for visual indication.

i


2/4

LIST OF FIGURES

FIGURE NO. TITLE PAGE NO.

1.4 Block Diagram of DC Motor Speed and Direction

Control using PWM Technique 2

2.2.2 Pin Diagram Of AT89S52 5

2.3.1 Architecture of Micro controller 8

2.3.2 Functional Block Diagram of micro controller 9

3.1 Block Diagram Of Clock Pulse Generator 12

3.2 Crystal Oscillator Equivalent Circuit 13

3.2.1 Diagram Of Note On Board Design 13

3.2.2 Phase Relationship Of Clock And E Clock 13

4.1 DC Motor 14

4.2 Working of DC Motor 15

6.1 Schematic Design 19

6.20 LCD Diagram 20

ii


3/4

6.21 Block Diagram Of LCD 21

6.3 LED Diagram 22

6.4 Block Diagram Of LED 23

7.1 IR Sensors 25

7.2 IR Sensors 25

8.1 Block Diagram of Regulated power supply 26

8.2 Transformer 27

8.3.1 Bridge Rectifier 28

8.3.2 Charging and discharging of capacitor 29

8.4 Three Terminal Of Regulator 29

LIST OF TABLES

iii


4/4

TABLE NO. DESCRIPTION PAGE. NO

Table-2.30 Port 1 Pin Specifications 6

Table-2.31 Port 3 Pin Specifications 7

Table-2.4.20 T2CON Timer/Counter 2 Control Register 11

Table-2.4.21 T2CON Timer/Counter 2 Mode ControlRegister

11

Table-3.2 External Crystal Parameters 12

Table-6.2 LCD Pin Description 20

iv

Documents

2. Abstract+ List of Figures+ List of Tables