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Level 2 physics: Brushless motors research assignment

The motor effect

Info -Source Information from source Ke ywords My own words/interpretation

revisionw

orld.com/

gcse-revi

sion/phys

ics/energ

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magnetic

-forces/m

otor-effec

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When two magnets are placed

close to each other, the

magnetic fields affect each

other produce a force

If a wire carrying a current is

placed inside this magnetic

field, a force is produced.

This is called the motor effect

The direction of the force will

depend on the direction of the

magnetic field and the direction

of the current in the field

Magnets

Direction

Magnetic

Current

Force

A force is produced when two

magnets are placed close enough

together, this force created is a

Ma gnetic field.

If you were to place a wire in this

magnetic field, you will find

another force is produced. This is

called the motor effect.

The magnetic field dictates the

direction of the force and the

direction the current in the field will

travel

http://ww

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The direction of the force -

and therefore the

movement of the wire - can

be determined using

Fleming’s left hand rule.

Direction

Movemen

t

Force

Field

The motor effect occurs when a

coil is charged with a current,

this same coil will now

experiences a force and moves

with the current. Building a

simple electric motor can be as

simple as using a coil of wire free

to rotate around two magnetic

poles.

Remember:

● thu M B – M ovement

● F orefinger – magnetic

F ield

● se C ond finger – C urrent

The force\'s direction is reversed

if either the direction of the

magnetic field is reversed or the

direction of the current is

reversed.

Advantages and Disadvantages of Brushless dc motors

http://m

buynow

.blogsp

ot.co.nz

/2013/0

5/whatr

e-adva

ntagesand-

dis

advant

ages-of

.html

Advantages:

Brushless motors offer several

advantages over brushed DC

motors, including high torque to

weight ratio, more torque per watt

(increased efficiency), increased

reliability, reduced noise, longer

lifetime (no brush and commutator

erosion), elimination of ionizing

sparks from the commutator, and

overall reduction of electromagnetic

interference (EMI).

Efficient

Torque

Ionizing

EMI

Commutator

Some of the advantages

when it comes to brushless

motors include that,

compared to a brushed dc

motor, a brushless dc motor

has a higher torque to weight

ratio, and a higher torque per

watt ratio.

Brushless motors also have

the advantage of noise

reduction and a longer

lifespan due to the non

contact technology

http://m

buynow

.blogsp

ot.co.nz

/2013/0

5/whatr

e-adva

ntagesand-

dis

advant

ages-of

.html

http://w

ww.ele

ctrical4

u.com/

brushle

ss-dcmotors/

Disadvantages:

For most people who have

brushless motor will say brushless

motor is expensive. That’s true. But

have you think about what cause

the problem. Brushed motors are

cheap to produce, but the brushes

wear out from rubbing against the

contact point and axle. Friction

from this contact also impedes

performance. For brushless motor,

as it appeared later than brushed,

regardless of technology or

materials, there are big challenges.

Also, electric controller is required

to keep the motor running. It offers

double the price of the motor.

The limited high power could be

supplied to BLDC motor,

otherwise too much heat weakens

the magnets and insulation of

winding may get damaged.

Expensive

Performance

Controller

Affordable

Quality

Friction

The main disadvantage of

brushless motors would have

to be the price. Because of

the cost of the components

and the delicate assembly of

the brushless dc motor.

Electric controllers are also

used in brushless dc motors,

boosting the price even

higher. The electric

controllers are required to

keep the motor running.

Another disadvantage of

brushless dc motors are the

high power supplied to the

the motor. The heat tends to

weaken the magnet and

could cause damage to the

internals of the brushless

motor.

Why brushless motors are used in computers

https://ww

w.quora.co

m/What-ar

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rs-used-ina-

CPU

Mostly in CPUs Motors are

used to run the Fans used

for cooling the processors

and Power supply units.

It will be enough to say that

we will see motors are used

only in the cooling systems

of CPUs.

Brushless DC Motors are

used. Brushless Motors are

super quiet (Due to absence

of brushes) and they have

higher speeds than Brushed

DC Motors.

Processors

Power

Supply

Cooling

Brushed

Brushless

Brushless motors are used to run

the fans that have the job of

cooling the computers

processors and the main power

supply unit.

These brushless motors are

commonly only used in the

cooling system of a computer\'s

cpu (central processing unit)

http://www.

pcbheaven

.com/wikip

ages/How_

PC_Fans_

Work/

The vast majority of PCs

has at least one of them.

They carry the heavy load to

keep your PC cool and

functional, either by

providing fresh air in the

box, or by forcing the hot air

to leave a hot surface by

pushing cool air.

As long as the motor is

concerned, i suppose that

all PC fans use brushless

motors. There are several

reasons that a brushless

motor should be used,

among them is the

reliability, the power

efficiency and the rpm

feedback

Functional

Reliability

Efficiency

Rpm

Feedback

Brushless

Another key reason brushless

motors are used in personal

computers are the fact that they

are built to carry the heavy load

of current needed to keep your

pc cool and functioning. This

process is carried out by either

providing fresh air into the box or

by forcing the hot air out of the

box, off of a hot surface.

The reliability of a brushless

motor is also a key reason they

are used in personal computers,

making maintenance of the fan

necessary. The reliability of a

computer fan is also important,

because if the fan were to stop

working it would overheat the

computer\'s cpu and damage

your pc, whilst also posing a fire

hazard.

Brushless motors and how they differ from a brushed motor.

Brushed

Motors

https://e

n.wikipe

dia.org/

wiki/Bru

shed_D

C_electr

ic_motor

A brushed DC motor is an

internally commutated electric

motor designed to be run from a

direct current power source..

Brushed DC motors can be varied

in speed by changing the operating

voltage or the strength of the

magnetic field. Depending on the

connections of the field to the

power supply, the speed and

torque characteristics of a brushed

motor can be altered to provide

steady speed or speed inversely

proportional to the mechanical

load .

Commutate

d

Direct-

Current

Varied-

Speed

Operating-

Voltage

Magnetic-

Field

Proportional

Inversely

Mechanical

To know the difference between a

brushed dc motor and a

brushless motor, you first have to

know how each of them operate.

This will clearly show the

difference between the two types

of motors:

A brushed dc motor is designed

to run from direct current as its

power source. This means that

the speed of a brushed motor can

be varied by changing the

magnetic field or the voltage used

in the motor.

A brushless motor however is

designed to rotate around a fixed

armature using the magnets

which are permanently fixed.

Brushless motors are designed

this way to avoid problems

caused by the current connecting

to the moving armature. However

brushless motors don’t have a

brush communicator incorporated

into their design, instead the

motor is kept running using a

device called the electronic

controller, which changes the

phase of the winding regularly in

an effort to keep the motor

turning.

In conclusion, brushed and

brushless motors differ in the

sense that the brushless motor is

powered by AC current signal

received by the drive motor. Also

that Brushed motors are

controlled by changing the

https://e

n.wikipe

dia.org/

wiki/Bru

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or

A typical brushless motor has

permanent magnets which

rotate around a fixed armature ,

eliminating problems associated

with connecting current to the

moving armature. An electronic

controller replaces the

brush/commutator assembly of

the brushed DC motor, which

continually switches the phase

to the windings to keep the

motor turning.

The controller performs similar

timed power distribution by

using a solid-state circuit rather

than the brush/commutator

system.

Brushless

Permanent

Armature

Current

Electronic

Controller

Switches

Distribution

Circuit

voltage where as the brushless

motor is controlled by an

electronic controller.

Key words used when explaining brushless motors:

Armature

https://en.wikipedia.org/wiki/

Armature_(electrical_engine

ering)

In electrical engineering , an

armature generally refers to

one of the two principal

electrical components of an

electromechanical or

electrical machine —

generally in a motor

The armature within a motor

refers to the conductive coil

within a motor that carries

current. This creates torque in

a spiraling shaft causing the

rotation inside the motor

Commutator

https://en.wikipedia.org/wiki/

Commutator_(electric)

A commutator is a moving

part of a rotary electrical

switch in certain types of

electric motors and electrical

generators that periodically

reverses the current direction

between the rotor and the

external circuit.

In a motor the commutator

serves to supply the motor

current to its windings. A steady

amount of rotating torque is

produced when you reverse the

direction of the current through

each half turn of a winding.

Electronic controller

https://en.wikipedia.org/wiki/

Electronic_speed_control

An electronic speed control

or ESC is an electronic circuit

with the purpose to vary an

electric motor \'s speed, its

direction and possibly also to

act as a dynamic brake . often

used for brushless motors

essentially providing an

electronically generated

three-phase electric power

low voltage source of energy

for the motor.

An electronic controller serves

to adjust the motor\'s speed

according to the phase of the

motors winding.

While also proving the motor

with a source of three-phase

low voltage power.

Torque

https://en.wikipedia.org/wiki/

Torque

Torque , moment , or

moment of force (see the

terminology below) is the

tendency of a force to rotate

an object about an axis,

fulcrum, or pivot.

Torque is the force of a

movement, and reflects on an

object’s force of travel circling

an a x is, pivot or fulcrum.

Research task by Lachlan Spargo...

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