Design, Construction and Testing of A Temperature Sensing Automatic Speed

Controller for Fan

Outlines:• Introduction• Objectives• Design Assumptions • Name of components• Block diagram• Circuit diagram• Description of components• Construction of the speed controller• Working procedure• PWM(Pulse Width Modulation)• Test Procedure• Result and Discussion• Conclusion and Recommendation

Introduction:What is the project?

The project is controlling the speed of a fan automatically with variation of temperature detected by a temperature sensor using microcontroller.

Control system:

There are two types of control system

1. Manual control system

2. Automatic control system

Here an automatic control system is used for this project

Automatic control system:

A control system in which regulating and switching operations are performed automatically in response to predetermined conditions.

How the system works?

At first the variation of surrounding temperature is detected by a temperature sensor, then using microcontroller unit the speed of the fan is controlled. That means when the temperature rises, the speed of the fan will increase and vice versa.

Why use an automatic speed controller?

Sometimes human beings waste power for nothing while using electric fan. It is always demanded for us to waste less energy. Most human beings feel the inconvenience about changing the fan speed level manually. So this speed control system automatically changes the speed level of fan according to temperature changes.

Objective:Objectives of this thesis are to-

I. design an automatic speed controller for fan based on temperature.

II. construct an automatic speed controller for fan based on temperature.

III. test an automatic speed controller for fan based on temperature.

Design Assumptions

• The design is based on appropriate sensing capability of temperature sensor and corresponding response of speed controller unit.

• Depending on the application, working temperature range varies. For this system temperature range was assumed 30 to 34 .℃ ℃

• Control system is assumed to have provision for working under different temperature increment or decrement such as 1 , 2 , ℃ ℃3 …etc. For this system temperature increment or decrement is ℃assumed 1 .℃

• Speed range was assumed from 2550 rpm to 4910 rpm. For each increment or decrement speed was varied through 550 to 600 rpm.

Name of Components:

Arduino Board (UNO) Temperature Sensor (DHT11) LCD Display DC Motor Electronic Speed Controller Battery (Power Supply) Fan

Block Diagram of the Speed Controller

LCD Display

DHT 11(Temperature

sensor)

LiPo Battery

BLDC(Brussless DC

Motor)

Arduino Board

ESC(Electronic speed

controller)

Circuit Diagram

Description of Components:

Arduino Board:

Arduino is a single-board microcontroller, intended to make the application of interactive objects and environments more easier. Basically this is very user friendly. There is a microcontroller unit embedded on it.The code is directly loaded from the computer.

Temperature Sensor:

Basically it is an electronic device that can sense the temperature which sends signal to the microcontroller unit. Here DHT11 is used. Its range is between 0 to50⁰c.

LCD Display:

LCD display is a flat panel electronic visual

display. 26×4 display board is used in this

project. Value of temperature in degree

celsius and corresponding value

of speed in rpm are displayed.

Electronic Speed Control:

An electronic speed control or ESC is simply

an electronic circuit which is used to control

the speed of dc motor. It can take upto 30Amp

Continuous current. It has the feature of automatic

power cut off, over heat protection, over voltage protection.

Battery:

Lithium-ion polymer battery is used here. It is rechargeable and it provides required power to arduino board and dc motor and other components. It can last for long time after charged once.

DC Motor:Brushless DC electric motor is a device powered by a DC electric source via an integrated power supply which produces an AC electric signal to drive the motor. It can give upto 10,300 rpm.

Construction of the speed controller

Construction of the speed controller(cont’d)

Working Procedure:Arduino Board is the main control unit of our construction. A microcontroller is embedded on the Arduino board. It is controlled by numerical coding loaded from computer. It is the brain of our construction. A LCD display is connected with the Arduino board which displays temperature reading and variation of speed of DC motor with respect to temperature . We have used DHT 11 as temperature sensor. It can sense temperature from 0 to 50℃. An electronic speed controller (ESC) is connected with the arduino board. It is used to control the speed of brushless DC motor(BLDC). A LiPo battery is used to provide sufficient energy. The BLDC motor can give up to 10,300 rpm.

PWM(Pulse Width Modulation)

Pulse-width modulation (PWM) is a modulation technique that conforms the width of the pulse, formally the pulse duration, based on modulator signal information. Here pwm is used for varying speed of the fan or dc motor corresponding to temperature reading from temperature sensor(DHT11).

Test Procedure

• The speed controller and motor were connected to battery. Then speed controller was switched on.

• At initial state LCD display was showing surrounding temperature at that moment and corresponding initial speed of the fan.

• Then the temperature was increased artificially from 30 to ℃34 with the temperature increment by 1 . ℃ ℃

• Variation of speed corresponding to temperature was observed from the LCD display.

Data taken from the speed controller in running condition

Observation

No

Temperature

Reading(℃)

Experimental

Fan

Speed(rpm)

Theoretical

Fan

Speed(rpm)

Error

Percentag

e(%)

01 30℃ 2423 2550 3.08

02 31℃ 3015 3150 4.29

03 32℃ 3580 3710 3.5

04 33℃ 4120 4310 4.41

05 34℃ 4750 4910 3.26

Result and Discussion

The speed controller controlled the speed of the fan according to preassigned condition. Speed of the fan increased as the surrounding temperature increased and it decreased as the temperature decreased. Increment of both temperature and speed can be changed according to user preferences by the modification in programming.So the speed controller performed as per the design.

Conclusion and Recommendation

A temperature sensing automatic speed controller for fan has been designed and constructed according to the design. The speed controller has been tested in various temperature condition and successful results have been found with minimum error. Errors have been found by comparing experimental rpm and theoretical rpm of fan which is around 3.7%.

Recommendation: Wi-fi facility can be integrated with the system. A keypad can be added for manual input. Humidity sensor can be added to the system.

THANK YOU