BLDC Motors

BLDC Motors
EVOLUTION
CONVENTIONAL DC MOTOR
PERMANENT MAGNET DC MOTOR (PMDC)
BRUSHLESS PERMANENT DC MOTOR (BLPMDC)

Conventional DC Motors
• Converts electrical energy to mechanical energy
• Principle- When a current carrying conductor placed in
a magnetic field experiences a force
• Stator is made up of forced steel with inward projected poles
and poles carry field windings and rotor is of silicon
steel stampings
BRUS
H
COI
L
Brushed DC
motor
Permanent magnet DC motor
• Construction of PMDC is similar to conventional dc motor
• Stator poles are replaced by suitable permanent magnets
• No need to have field windings .
Brushless Permanent Magnet DC
Motor
• Brushless DC electric motor also known as electronically commutated
motors (ECMs, EC 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 .
– magnetic fields generated by the stator and rotor rotate at the
same frequency
– no slip
• The stator consists of several coils which current is led through Creating
a magnetic field that makes the rotor turns .
PMBLDC Motor
Construction of BLDC
• It consist of two parts mainly stator & rotor
Stator
 Stator is made up of silicon steel stampings with
slots.
 The slots are accomodated armature windings.
 This winding is wound with specified
no.of poles(even
number).
 This winding connected a dc supply through a
power electronic switching circuits ( inverter circuits) .
Rotor
 Rotor is of permanent magnet
 no of poles on rotor is same as that of stator
 Rotor shaft carries a RPS (Rotor position sensor) and it
provides information about the position of shaft at any instant
to the controller which sends signal to the electronic
commutator .
 The electronic commutator function is same as that
of mechanical commutator in DC motor
BLDC Motor
Stator
BLDC Motor
Rotors
Working Of BLDC Motor
• The rotor and stator of a BLDC motor are shown in the fig . It
is clear that, the rotor of a BLDC motor is a permanent
magnet.
The stator has a coil arrangement, as illustrated; The internal winding of the
rotor is illustrated in the Fig(core of the rotor is hidden here). The stator has 3
coils,named A, B and C.
Out of these 3 coils, only one coil is illustrated in the Fig for simplicity. By
applying DC power to the coil, the coil will energize and become an
electromagnet .
The operation of a BLDC is based on the simple
interaction between the permanent magnet force and the
electromagnet. In this condition, when the coil A is energized,
the opposite poles of the rotor and stator are attracted to each
other (The attractive force is shown in green arrow). As a result
the rotor poles move near to the energized stator.
As the rotor nears coil A, coil B is energized. As the rotor nears
coil B, coil C is energized. After that, coil A is energized with the
opposite polarity . This process is repeated, and the rotor
continues to rotate. The DC current required in the each coil is
shown in the following graph.
Improving The BLDC Performance
Unlike a brushed DC motor, the commutation of BLDC

motor is controlled electronically.
It is important to know the rotor position in order
to understand which winding will be energized
following the energizing sequence.
Rotor position is sensed by different ways some

of them are
1) Hall sensors 2) Optical encoders
Hall Sensors
When a magnetic field applied to a system with
electric current a hall voltage Perpendicular to the
field and to current is generated.This was discovered
by Edwin Hall in 1879.
COMPARISON BETWEEN BDC AND
BLDC
Advantages
• Increased Reliability & Efficiency
• Longer Life
• Elimination of Sparks from Commutator
• Reduced Friction
• Faster Rate of Voltage & Current

Disadvantages
• Requires Complex Drive Circuitry
• Requires additional Sensors
• Higher Cost
• Some designs require manual labor

(Hand wound Stator Coils)
Applications
• Consumer: Hard Drives, CD/DVD Drives, PC Cooling Fans,
toys, RC airplanes, air conditioners
• Medical: Artificial heart, Microscopes, centrifuges,
Arthroscopic surgical tools, Dental surgical tools and Organ
transport pump system.
• Vehicles: electronic power steering ,personal electric vehicles
• Airplanes: an electric self launching sailplane, flies with
a 42kW DC/DC brushless motor and Li-Ion batteries and
can climb up to 3000m with fully charged cells
TORQUE-SPEED CHARACTERISTICS
PERMANENT MAGNETIC
SYNCHRONOUS MOTOR
Introduction
• Synchronous motors are the most widely used steady-state 3-
phase AC motors, which convert electrical energy into
mechanical energy.
• Mainly used in power systems to improve the power factor.
• Vehicles: electronic power steering ,personal electric vehicles
• Non-excited and DC excited synchronous motors- operate
according to the magnetic power of the motor.
• Reluctance motors, hysteresis motors, and permanent magnet
motors are the non-excited synchronous motors.
Permanent Magnet
Synchronous Motor
• It is a type of AC synchronous motors.
• Field is excited by permanent magnets that generate sinusoidal
back EMF
• Rotor and stator same as induction motor.
• Permanent magnet is used as a rotor to create a magnetic field.
• There is no need to wound field winding on rotor.
• Also known as a 3-phase brushless permanent sine wave motor.
Permanent Magnet
Synchronous Motor Theory
• Very efficient, brushless, very fast, safe, and give high dynamic
performance when compared to the conventional motors.
• Produces smooth torque, low noise and mainly used for high-
speed applications like robotics.
• 3-phase AC synchronous motor that runs at synchronous speed
with the applied AC source
• Instead of using winding for the rotor, permanent magnets are
mounted to create a rotating magnetic field.
• No supply of DC source, these types of motors are very simple
and less cost.
• Stator with 3 windings installed on it and a rotor with a
permanent magnet mounted to create field poles.
• 3-phase input ac supply is given to the stator.
Working Principle
• Permanent magnet synchronous motor working principle is
similar to the synchronous motor.
• Depends on the rotating magnetic field that generates
electromotive force at synchronous speed.
• Stator winding is energized by giving the 3-phase supply, a
rotating magnetic field is created in between the air gaps.
• Produces the torque when the rotor field poles hold the rotating
magnetic field at synchronous speed and the rotor rotates
continuously.
Working principle on next page

Working Principle of PMDC
The permanent magnet synchronous motor working principle is

similar to the synchronous motor. It depends on the rotating
magnetic field that generates EMF at synchronous speed. When the
stator winding is energized by giving the 3-phase supply, a rotating
magnetic field is created in between the air gaps.
This produces the torque when the rotor field poles hold the rotating
magnetic field at synchronous speed and the rotor rotates
continuously.
Construction
• Similar to the basic synchronous motor.
• Permanent magnets used in the PMSM are made up of
samarium-cobalt and medium, iron, and boron because of their
higher permeability.
• Most widely used permanent magnet is neodymium-boron-iron
because of its effective cost and ease of availability.
• Based on the mounting of the permanent magnet on the rotor, the
construction of a permanent magnet synchronous motor is
divided into two types.
1. Surface-mounted PMSM
2. Buried PMSM or Interior PMSM

Surface-mounted PMSM
Buried PMSM or Interior PMSM

Permanent Magnet
Synchronous Motor vs BLDC
Advantages
• Provides higher efficiency at high speeds
• Available in small sizes at different packages
• Maintenance and installation is very easy than an induction motor
• Capable of maintaining full torque at low speeds.
• High efficiency and reliability
• Gives smooth torque and dynamic performance
Disadvantages
• These type of motors are very expensive when compared to
induction motors
• Somehow difficult to start-up because they are not self-starting
motors.
Applications
• Air conditioners
• Refrigerators
• AC compressors
• Washing machines, which are direct-drive
• Automotive electrical power steering
• Machine tools
• Large power systems to improve leading, and lagging power
factor
• Control of traction
• Data storage units.
• Servo drives
• Industrial applications like robotics, aerospace, and many more.

BLDC Motors

Uploaded by

Copyright:

Available Formats

BLDC Motors

Uploaded by

Document Information

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

BLDC Motors

Uploaded by

Copyright:

Available Formats

BLDC Motors

PERMANENT MAGNET DC MOTOR (PMDC)

BRUSHLESS PERMANENT DC MOTOR (BLPMDC)

Unlike a brushed DC motor, the commutation of BLDC

Rotor position is sensed by different ways some

• Elimination of Sparks from Commutator

• Faster Rate of Voltage & Current

• Requires additional Sensors

• Some designs require manual labor

Working principle on next page

The permanent magnet synchronous motor working principle is

2. Buried PMSM or Interior PMSM

Buried PMSM or Interior PMSM

You might also like