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Difference between BLDC motors and BDC motors
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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