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The Dc Motor Speed Control Methods Engineering Essay

Abstraction

This paper describes the Matlab and simulink converts into actuality of the DC motor velocity control methods, viz. field opposition, armature opposition control methods and armature electromotive force, and feedback control system for DC motor thrusts and this paper describes mathematical modeling, simulation of DC motor system utilizing computing machine simulations Matlab and simulink, by this system response to alter assorted parametric quantities like system stableness, perturbations, analysis and optimisation of theoretical account parametric quantities with regard to the quality of control. If simulation techniques are used for finding the control parameters a simulation theoretical account is necessary, which has to be constructed from the analytical theoretical account.

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Introduction

DC Motor is an electrical motor and it most normally used in an electrical device for easy to drive the instruments, steel turn overing Millss, electric Cranes, and robotic operators due to precise, broad, simple, and uninterrupted control features. To command the velocity of low power DC Motor rheostatic armature control method were used. The basic parts of the DC motor are- axle, rotor ( armature ) , stator, commutator, field magnet, and coppices. In the geometry of coppices, commutator contacts, and rotor twists are arranged in such a mode so that when power is applied so mutual oppositions of the energized twist and the stator magnets are misaligned and the rotor will get down to revolve until it is about aligned with the stator ‘s field magnets. When the rotor reaches to alignment, the coppices move to following commutator contacts, and stimulate the following twist.

There are variable types of DC Motor available in market with the good and bad qualities. Bad quality means slowdown in efficiency. To retrieve or halt this sort efficiency job accountant is introduce in the system.

Brushed DC motors are most widely used in applications and its ranging from plaything to push-button adjustable auto seats. Brushed DC ( BDC ) motors are cheap but easy to drive.

Brushed DC motors are easy available in all size and form with the broad scope from large-scale industrial theoretical accounts to little motors for light applications ( such as 12 V DC motors ) .

.

BDC motors are most normally used in easy to drive, with variable velocity and high start-up torsion applications.

Aim

The Fig.1 shows the parallels electrical circuit.

Modeling

The circuit which was given is drawn in the Matlab by utilizing simulink. In the circuit diagram the flow of current

BLOCK DIAGRAM

Figure shows the block diagram of DC motor

TRANSFER FUNCTION

K/ { ( Ls+R ) ( Js+f ) +K2 }

i?±

1/s

Vapp

Fig 4.1. Transfer Function

State SPACE MODEL

As we know that,

V- .… . ( 1 )

….. ( 2 )

Substituting equation ( 2 ) in ( 1 )

… … . ( 3 )

… .… ( 4 )

…… . ( 5 )

Substituting ( 5 ) in ( 4 )

– ……… ( 6 )

Differentiating ( 6 ) , we get

……….. ( 7 )

Puting ( 3 ) in ( 7 ) , we get

……… ( 8 )

Now

………… ( 9 )

Substituting ( 9 ) in ( 8 ) , we get

We know that x=Ax + Bu

Y=Cx + Du

X=

The State Space Model represents by the additive equation and it is written as.

x= Ax + Bu

Y = Cx + Du

Below figure shows the province infinite theoretical account ( Calculation is in appendix )

Figure 5.1 State Space Model

PHYSICAL System

See a DC Motor, in this electrical circuit of the armature and free organic structure diagram of rotor are shown in figure below.

hypertext transfer protocol: //zone.ni.com/cms/images/devzone/tut/mpm-2-motor1.gif

Fixture: – DC Motor is a common actuator in control systems.

Brushed DC Motor basicss

A Brushed DC Motor consists of stationary fixed lasting magnets i.e. stator, a revolving electromagnetic i.e. rotor and flux, which is concentrated by metal. Rotor rotate by the attractive force of the opposite poles and repulsive force of the similar poles, it cause to bring forth torsion and torque Acts of the Apostless on rotor and so do it turn. As the rotor start to revolve or turn so fixed coppices make and interrupt the contact in such a manner that with the revolving sections ( commuting ) . The rotor spiral of the brushed motor energized and de-energized in such a manner so that the rotor start to bends. By reassigning the power to the motor, current generate in rotor spirals and therefore the North and south poles are reversed and because of the motor change the way. From the Strength of the magnetic field, velocity and torsion of the motor depend

Figure ( 1 ) Brushed DC Motor

Principle OPERATION

Construction and operation of the Brushed DC Motor is shown below in figure ( 2 ) .for the building of the BDC motor ever the same constituents are required i.e. Stator, rotor, commutator and coppice.

Figure ( 2 ) Simple two-pole brushed DC Motor

Stator

The rotor surrounded by the stationary magnetic field which is generated by the stator and this filed is generated by the lasting magnet or electromagnetic twist. On the building of the stator, different types of BDC distinguish.

Rotor

Rotor is besides known as an armature and it is made up of one or more twists. Magnetic field is produce when they energized. When the opposite pole of the magnetic poles, pull to each other which is generated by the stator, and doing the rotor to turns. The opposite poles are ever pulling to each other. As the motor turns, the twists are being invariably energized. This divergence of the field in the rotor is called as an armature.

Brushs and commutator

There is no demand of accountant in BDC to exchange current in motor twist. The commuting twist of the BDC motor is done automatically. Reside on the axel of rotor there is a metameric Cu arms called commutator. Carbon brushes slides over the commutator coming in a contact with the different sections of the commutator as the motor starts to turn. When the electromotive force is applied across the coppices of the motor so dynamic magnetic field is generated inside the motor. Brushes and commutator are the most of import parts of the BDC motor that are most prone to have on because they are the skiding portion to each other.

Speed Control

The Speed of a DC Motor is straight relative to the electromotive force. By utilizing the digital accountant electromotive force can be control and to bring forth the mean electromotive force pulse-width modulated ( PWM ) signal is used. In motor there is a motor weaving which acts as a low base on balls filter so PWM develop a suited current in the motor twist.

Advantage

Cheap in monetary value because low cost of building.

Widen a life by replacing a coppice.

Cheap motor and simple control.

Speed/Torque is normal at high velocity.

On fixed velocity no control is required, Controller is required merely at variable velocity in this status same accountant can be used.

Disadvantage

Care is required for brushed DC Motor because of coppice.

If the coppice clash additions, cut down the utile torsion.

Heat dissipation is hapless because of internal rotor building.

Speed scope is limited because of the mechanical restriction on coppices.

Life is besides shorter.

Noise is generated due to brush.

Application illustrations:

traveling playthings, fans, pressmans, automatons, electric motorcycles, -doors, -windows, -sun roofs, -seats, sociables, nutrient processors, can openers, liquidizers, vacuity cleaners, toothbrushes, razors, java bombers, etc.

Physical Parameters

Moment of inactiveness of the motor ( J ) = 9.89 E-7 kilogram Nm s/rad

Muffling ratio of the mechanical system ( B ) = 5.84E-7 Nm s/rad

Electromotive force or motor changeless ( K=Ke=Kt ) = 0.008 Nm/-w

Electric opposition ( R ) = 0.80 ohms

Electric induction ( L ) = 0.00041H

Friction coefficient, degree Fahrenheit

Input ( V ) : Beginning Voltage

Output ( theta ) : place of shaft

the rotor and shaft are assumed to be stiff

Decision

Brushed DC motors are really simple to utilize and easy to command,

which makes them a short design-in point. PIC

microcontrollers, particularly those with CCP or ECCP

faculties are ideally suited for driving BDC motors.

Refference

hypertext transfer protocol: //www.wiringdiagrams21.com/2009/09/26/circuit-diagram-for-dc-motor-control-by-a-collins

hypertext transfer protocol: //www.nxp.com/documents/application_note/AN10513.pdf

hypertext transfer protocol: //ww1.microchip.com/downloads/en/AppNotes/00905a.pdf

hypertext transfer protocol: //www.orientalmotor.com/MotionControl101/AC-brushless-brushed-motors.html

hypertext transfer protocol: //ww1.microchip.com/downloads/en/AppNotes/00885a.pdf

hypertext transfer protocol: //www.dynetic.com/brushless % 20vs % 20brushed.htm

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