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temperature based fan speed controller ppt download

Temperature Based Fan Speed Control
Introduction:
In this project we will be using the concept of firing angle to control fan speed. Basically in this project we will be controlling fan speed with respect to the temperature.
The system will get the temperature from the temperature Sensor via the ADC and it will control the speed according the set poing set by the user. The circuit consists of four switches based keypad, in which two buttons are used to increment and decrement the temperature value and the remaining two buttons are used to activate and deactivate the whole system.
In this project, an 8051 based microcontroller forms the processing part, which firstly senses the temperature via the ADC the controller then compares the data with the set temperature which the user can set via the keypad. If the current temperature is greater than the set temperature the controller turns ON the fan and the set speed will be proportional to the difference between the set temperature & the current temperature. If the current temperature is less than the set temperature the fan will be turned OFF. We will be using a Triac to provide the requirefiring angle to the fan and the fan speed will change accordingly. We will be interfacing four seven segment displays which will be used to display the set temperature as well as the current temperature.

Temperature based fan controller uses microcontroller AT89S8253 that is capable of taking decisions on the basis of input. Crystal oscillator is used to generate frequency it is of 10MHz. This crystal is coupled with 22pf /33pf capacitor so that microcontroller circuitry get complete and it can work with programming.


The complete working of this system can be divided in the following blocks for easier understanding:

Temperature Sensor

It consists of the sensor which measures the temperature of its surrounding and communicates that data to the microcontroller. The sensor used here is DS18B20.It is a highly sensitive sensor with a resolution of less than 0.50C. It communicates with microcontroller using one wire protocol of communication

The temperature-controlled fan designed with microcontroller is quite useful for conference halls, auditoriums, cinema halls, and other commercial organizations where many people gathered together, and lot of fans are required at these places. Depending up on the weather condition, organizers of the above places are supposed to be control each and every fan, otherwise lot of energy will be wasted. Controlling each and every fan manually is highly impossible; there by this project work is taken up, which controls the fan automatically depending upon the temperature. Here for the demonstration purpose single fan is considered, but in practical all the fans can be connected to this single instrument, so that all the fans rotates equally.
The basic concept of this project work is, depending upon the room temperature to control the fan speed automatically. Since our weather conditions are widely varied, temperature up and downs are common in our country. When the temperature is less then 20 0C fan is not required, there by a facility is provided in the system that the fan will be switched off automatically at less then 20 0C. The system is programmed to run the fan at its maximum speed at 40 0C. There fore the fan speed varies linearly between 20 0C to 40 0C.
Semi conducting device is used as temperature sensor, the output of this sensor is amplified and fed to A/D converter for converting the analog information produced according to the temperature into digital. The ADC is interfaced with microconroller, depending up on the digital value proportionate to the temperature, the controller displays in degree centigrade at the same time, the controller also generates square pulses which are applied to the thyristor gate through opto-isolator. Depending up on the duty cycle, fan speed can be controlled automatically.
The micro-controller is programmed to convert the digital data obtained from A/D Converter in to corresponding pulse rate, the pulse rate varies according to the temperature.