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%