Design And Implementation Of A Microcontroller Based DC Motor Control

CHAPTER ONE
1.0 INTRODUCTION
Motion control plays a vital role in industrial automation. Manufacturing plants in industries like chemical, pharmaceutical, plastic and textile, all require motion control. And it may be a flat-belt application, flow control application or mixing of substances. Different types of motors—AC, DC, servo or stepper—are used depending upon the application. Of these, DC motors are widely used because controlling a DC motor is somewhat easier than other kinds of motors.

The motion of a DC motor is controlled using a DC drive. DC drive changes the speed and direction of motion of the motor. Some of the DC drives are just a rectifier with a series resistor that converts standard AC supply into DC and gives it to the motor through a switch and a series resistor to change the speed and direction of rotation of the motor. But many of the DC drives have an inbuilt microcontroller that provides programmable facilities, message display on LCD, precise control and also protection for motors. Using the DC drive you can program the motion of the motor, that is, how it should rotate.

OBJECTIVE OF THE PROJECT
The objective of this work is to design a device that controls, that is, Start, stop and change of direction OR the speed of a dc motor controlled by pushbutton switches and indicated by LED. The heart of this project is ATmega8 (AT89C52) microcontroller. This controller consist of 2 PWM modes

1.2 PURPOSE OF THE PROJECT
The purpose of a motor speed control is to take a signal representing the demanded speed and drive the motor at that speed and direction.

1.3 SIGNIFICANCE OF THE PROJECT
Speed control of DC motor can achieve using mechanical or electrical techniques but they require large size hardware to implement but Microcontroller based system provides easy way to control the speed of DC motor. Using this PWM method, we can save the power.

1.4 APPLICATIONS OF THE PROJECT

• Used in industries to control the speed of motors.
• Used in shopping malls.
• We can use this concept to control the light intensity.

1.5 LIMITATION OF THE PROJECT
Drawback of this method of dc motor speed control is that they are not able to control the motor speed smoothly at lower levels, and as the desired speed is decreased, the torque of the motor also decreases proportionately. Due to this, at any unpredictable point the motor may just halt very abruptly. Also, during power ON, the motor may just not start up at lower speed settings and may require an initial boost by increasing the setting. Such situations are pretty undesirable and do not constitute an ideal speed control.

1.6 SCOPE OF THE PROJECT
DC motor speed controllers are very useful for controlling the motion of robotic and industrial automation systems. The controller presented here uses the pulse-width modulation (PWM) technique. The PWM wave for speed control is generated using Atmel AT89C52 microcontroller. To control the speed of the DC motor, you need a variable-voltage DC power source. When the DC motor is switched on, it takes certain time to reach the full speed. As soon as the power supply is switched on, the DC motor starts gaining speed and if you switch off the power supply before it reaches the maximum rated speed, it starts to slow down.

In case switching on and switching off are done in quick succession, the motor rotates at a slower speed between zero and full rated speed. This is what a PWM technique based controller does: it switches the motor ‘on’ and ‘off’ with a pulse train. To control the motor speed, it varies (modulates) the width of the pulses—hence the pulse-width modulation. When the motor is ‘on’ for a short period and ‘off’ for a long one, it will rotate slowly. When the motor is ‘on’ for most of the time and ‘off’ only for a short while, it will rotate at higher speed, say, nearly at full (maximum) rated speed. In this work, dc motor:

1. Is controlled through microcontroller AT89C51.
2. Message displayed on the LCD module.

• Start, stop and change of direction of the motor controlled by pushbutton switches and indicated by LED.

1. Changes the running mode of the motor to continuous, reversible or jogging.
2. Changes the speed of the motor. Time settings are possible for forward and reverse running of the motor

1.7 PROJECT WORK ORGANIZATION
The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to the study. In this chapter, the background, significance, objective limitation and problem of the study were discussed.

Chapter two is on literature review of this study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.