Design a MOSFET Circuit

• The circuit diagram of MOSFET circuitz

• Testing of mosfet circuit

 MOSFET (IRFZ46N)

• The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET,or MOSFET)is a transistor used for amplifying or switching electronic signals. Although the MOSFET is a four-terminal device with source (S), gate (G), drain (D), and body (B) terminals, the body (or substrate) of the MOSFET often is connected to the source terminal, making it a three-terminal device like other field-effect transistors. When two terminals are connected to each other (short-circuited) only three terminals appear in electrical diagrams

• Below shown mosfet IRFZ46N have been used for switching and amplifying signal from DAQ.

Metal–oxide–semiconductor field-effect transistor ( Final Control Element)

• MOSFET is same as a common type of transistor in which charge carriers, such as electrons, flow along channels. The width of the channel, which determines how well the device conducts,is controlled by an electrode called the gate, separated from channel by a thin layer of oxide insulation. 

• The insulation keeps current from flowing between the gate and channel. MOSFETs are useful for high-speed switching applications and also on integrated circuits. In this project, MOSFET used to amplify the signal from PWM signal to DC motor.

Project Overview

Project Overview / Introduction:

• ·         Introduction of DC motor speed control

Direct current (DC) motors have variable characteristics and are used extensively in variable speed drives. DC motor can provide a high starting torque and it is also possible to obtain speed control over wide range. Why do we need a speed motor controller? For example, if we have a DC motor in a robot, if we just apply a constant power to each motor on a robot, then the poor robot will never be able to maintain a steady speed. It will go slower over carpet, faster over smooth flooring, slower up hill, faster downhill, etc. So, it is important to make a controller to control the speed of DC motor in desired speed.

DC motor plays a significant role in modern industrial. These are several types of applications where the load on the DC motor varies over a speed range. These applications may demand high-speed control accuracy and good dynamic responses.

In home appliances, washers, dryers and compressors are good examples. In automotive, fuel pump control, electronic steering control, engine control and electric vehicle control are good examples of these. In aerospace, there are a number of applications, like centrifuges, pumps, robotic arm controls, gyroscope controls and so on

There are two major parts of this system:

i. Hardware Interfacing

- connecting the computer to external equipment.

ii. Software Design 2

- programming the computer to carry out its control calculation (control laws) while interacting with external components. Lab View will be used to program the DAQ card since this program is easy to learn and user friendly.

            The system (plant) under control is a continuous-time system.  The ‘heart’ of the controller is LabView Software. The problem of realizing this system is mainly one of developing computer program.  and figure below shows the block diagram of the project.

Closed Loop Block diagram of speed measurement of a DC motor system

No	Component	Description
1	12V Dc Motor	Brushless Motor
2	Mosfet	Amplifier signal PWM from DAQ to motor
3	Optical Encoder	Speed sensor and Generate pulse
4	DAQ	Interface between  software and hardware
5	Lab View	As a program to do a process control
6	PWM	Final control element  that control duty cycle from  0-100%

Softwere and Programmer as Controller of The Project

Title of activity: list the component that may use

Objective: List which component should be used in project and determine the controller of the project

Content: 

this is transducer measure the speed:

Example of Rotary Encoder Kit

DC Motor

LabView Software.

• LabVIEW (short for Laboratory Virtual Instrumentation Engineering Workbench) is a platform and development environment for a visual programming language from National Instruments. The purpose of such programming is automating the usage of processing and measuring equipment in any laboratory setup. The graphical language is named "G" (not to be confused with G-code). Originally released for the Apple Macintosh in 1986, LabVIEW is commonly used for data acquisition,instrument control, and industrial automation on a variety of platforms including Microsoft Windows, various versions of UNIX, Linux, and Mac OS X. The latest version of LabVIEW is version LabVIEW 2011, released in August 2011.

• LabVIEW ties the creation of user interfaces (called front panels) into the development cycle. LabVIEW programs/subroutines are called virtual instruments (VIs). Each VI has three components: a block diagram, a front panel and a connector panel. The last is used to represent the VI in the block diagrams of other, calling VIs. Controls and indicators on the front panel allow an operator to input data into or extract data from a running virtual instrument. However, the front panel can also serve as a programmatic interface. Thus a virtual instrument can either be run as a program, with the front panel serving as a user interface, or, when dropped as a node onto the block diagram, the front panel defines the inputs and outputs for the given node through the connector pane. This implies each VI can be easily tested before being embedded as a subroutine into a larger program. The graphical approach also allows non-programmers to build programs by dragging and dropping virtual representations of lab equipment with which they are already familiar. The LabVIEW programming environment, with the included examples and documentation, makes it simple to create small applications.

Result and analysis

For time being I have to decide which one should i choose either I need control Dc speed motor using LAB View Or Microprocessor.. All the component and function still remain but the controller of speed is different.  Basically, both can be used. the advantages is in many industries, lab view is quiet demand.

Conclusion

I decided to choose Labview as the software to control the DC speed motor.

Previous Project and Research From The Books and Internet

Title of activity- Do some research and what need to be attached at the project

Objective- got overview of the project by looking video for research and leaned what circuit should be constructed.

Content-these are some research and idea for my project

1.      http://www.youtube.com/watch?v=adkq_apZeTk (speed control)

2.      http://www.youtube.com/watch?v=S9dVIOP5oUE ( Closed loop by using lab view)

3.      http://www.youtube.com/watch?v=cn83jR2mchw(sensor need to be used)

Results and analysis

-Problem encounter

1.If I use infra red (IR) as transmitter and receiver for optical encoder for more narrow light. In theory, these will allow me to increase the resolution of optical encoder by increasing the number of slots.  Thus, it will reduce the steady state error .Besides, time for getting data and for controller to take action also can be reduced.  So, the motor speed response will become better. So, we need to try weather it is function or not.

2. Due to the size of photodiode which is quite big, the number of slots at cardboard that can be used is 8. The rotary encoder also have a less durability to do a constant test, because it easy to broke.

Conclusion

I have detected  some problem  in sensor and I choose optical encoder because  it produce pulse and it is easier to compare to lab view or PIC.

Proposal of The Project

Title of activity: 1. Do a proposal report writing

                            2. Do a research about the component need to be used

                            3. Know concept of feedback of closed looped system    

Objective-   -To do a proposal for final year project

                    - Give overview of the final year project 

1^st content       :

Obtain format of proposal report writing from lecturer which is:-

-abstract (basic concept of the project)

-introduction of project

-problem statement (why we choose this project and how it is benefit to the technology)  

-Literature review (theory of the project)

-components

-flow chart

-Block diagram

-Related sofwere

-Work plan

-budget

2^nd content       :

List  of the component

Budget

Hardware

No	Component
1	IC 16f877a
2	Servo motor
3	Rotary encoder kit
4	Slotted disc
5	Output shaft
6	Optical sensor

Software

No	Component
1	DAQ card
2	Lab View software
3	Microcontroller

Motor controller circuit

No	Component	Quanity
1	Voltage regulator (LM805)	1
2	Resistor	12
3	Motor Drive (L298)	1

Conclusion

Anything idea and flow of the project should be updated in my Proposal for my project( Closed loop controlled motor using PWM ). From the proposal I can see the overview of the project.