Brushless DC electric motor

卡帝諾

General Definition• BLDC motors are synchronous motors that are powered by a DC electric

source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor

Types of Construction

Inrunner (Conventional)• Rotational core is within the motor’s can.

• Permanent Magnets are part of the rotor and there are 3 stator windings surround it.

• They can run up as high as 11000 RPM per volt.

• No torque

Outrunner• the stator coils form the

center (core) of the motor, while the permanent magnets spin within an overhanging rotor which surrounds the core.

• Spins slower, but has greater torque than Inrunner

• Typically has more poles

The flat or axial flux type

• uses stator and rotor plates, mounted face to face

Physical RepresentationBrushed vs Brushless

Brushed(SERIE WOUND FORKLIFT MOTOR)

DRIVE SHAFT

ELECTROMAGNET

COMMUTATOR

COIL

BRUSH

CHECK HOW STATOR IS

MAGNETIZED

• AFTER CHECKING THE STRATORFIELD, WE DETERMINE THATTHERE ARE 2 POLES (NORTH ANDSOUTH)

WHEN THE ROTOR IS

INTRODUCED, THE FLUX

WILL BEND BECAUSE THE

ROTOR HAS HIGHER

MAGNETIC

PERMEABILITY THAN AIR.

WHEN THE COMUTATOR IS

INTRODUCED AN ELECTRIC

CURRENT FLOWS BUILDING A

SECOND MAGNETIC FIELD

AROUND THE ROTOR

CURRENT WILL FLOW

THROUGH ALL 3 COILS, YET

ONE COIL WILL ALWAYS BE

CONNECTED DIRECTLY TO

THE CURRENT HENCE

GIVING THE ROTATING

MOTION.

Brushless(CD ROM MOTOR)

WE CAN OBSERVE THAT WE

HAVE 2 WINDINGS.

A PAIR OF WINDINGS ARE

CONNECTED TO PLUS POLE

VOLTAGE SOURCE Vcc, WHILE THE

OTHER PAIR OF WINDINGS ARE

CONNECTED TO GROUND VIA 2

ELECTRONIC SWITCHES

ONE SWITCH IS CLOSED

TO GENERATE A STATOR

FIELD. THE TWO FIELDS

TRY TO ALIGN AND THEY

START SPINNING.

THEN THE SWITCH CLOSES AND

THE OTHER OPENS GENERATING A

SECOND FIELD, HENCE IT KEEPS

THE SPINNING. A HALL EFFECT

SENSOR CAN BE INTEGRATED.

Function of MCU in BLDC motor

PID Regulation

• The ATmega32M1 microcontroller controls the speed through a PID corrector.

• 3 Main coefficients:

KP: Motor Response Time

KI: Cancels the static error.

KD: position regulator

Conclusion

Brushed• PROS

• inexpensive and reliable

• simple control or no control at all in fixed-speed designs.

• CONS

• require periodic maintenance

• brush friction increases and viable torque decreases. (Not in the case of toothbrush)

• inadequate heat dissipation caused by the rotor limitations

• high rotor inertia

• low speed range

• electromagnetic interference

Brushless• PROS

• more accurate in positioning apps

• require less and sometimes no maintenance

• speed/torque

• no power loss across brushes

• high output power

• small size

• better heat dissipation

• higher speed ranges

• low-noise operation.

• CONS

• higher cost of construction

• Complex and expensive control strategies

• require a controller that can cost almost as much as if not more than the BLDC motor it governs

• In general I would conclude the following:

BLDC motors should not be used for every product. A perfect example are toy robots targeting youngsters. It will be just a waste of money.

BLDC motors should be used for computer hard drives, mechanical-based media players, electronic-component cooling fans, cordless power tools, HVAC and refrigeration, industrial and manufacturing systems, and direct-drive turntables.

As an automobile enthusiast, I am eager to see the use of BLDC engines on HEV cars. I believe that by improving the torque, heat dissipation, electromagnetic interference, and high rotor inertia, a HEV will have the same power as a fuel vehicle.

Bibliography• Peng Zhang. Industrial Control Technology: A Handbook for Engineers and

Researchers.

• AVR194: Brushless DC Motor by ATMEL

• Brushless DC (BLDC) Motor Fundamentals by Padmaraja Yedamale, Microchip Technology Inc.

• DIY Electric Car: 04 DC Motor Basics by Benjamin Nelson

• https://www.youtube.com/watch?v=C1-klL3B9LU