18-08-2011, 01:01 PM
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INTRODUCTION
Brushless Direct Current (BLDC) motors are one of the
motor types rapidly gaining popularity. BLDC motors
are used in industries such as Appliances, Automotive,
Aerospace, Consumer, Medical, Industrial Automation
Equipment and Instrumentation.
As the name implies, BLDC motors do not use brushes
for commutation; instead, they are electronically commutated.
BLDC motors have many advantages over
brushed DC motors and induction motors. A few of
these are:
• Better speed versus torque characteristics
• High dynamic response
• High efficiency
• Long operating life
• Noiseless operation
• Higher speed ranges
Construction & working principle
BLDC motors are a type of synchronous motor. This
means the magnetic field generated by the stator and
the magnetic field generated by the rotor rotate at the
same frequency. BLDC motors do not experience the
“slip” that is normally seen in induction motors.
BLDC motors come in single-phase, 2-phase and
3-phase configurations. Corresponding to its type, the
stator has the same number of windings. Out of these,
3-phase motors are the most popular and widely used.
This application note focuses on 3-phase motors
STATOR
The stator of a BLDC motor consists of stacked steel
laminations with windings placed in the slots that are
axially cut along the inner periphery (as shown in
Figure 3). Traditionally, the stator resembles that of an
induction motor; however, the windings are distributed
in a different manner. Most BLDC motors have three
stator windings connected in star fashion. Each of
these windings are constructed with numerous coils
interconnected to form a winding. One or more coils are
placed in the slots and they are interconnected to make
a winding. Each of these windings are distributed over
the stator periphery to form an even numbers of poles.
There are two types of stator windings variants:
trapezoidal and sinusoidal motors. This differentiation
is made on the basis of the interconnection of coils in
the stator windings to give the different types of back
Electromotive Force (EMF). Refer to the “What is
Back EMF?” section for more information
INTRODUCTION
Brushless Direct Current (BLDC) motors are one of the
motor types rapidly gaining popularity. BLDC motors
are used in industries such as Appliances, Automotive,
Aerospace, Consumer, Medical, Industrial Automation
Equipment and Instrumentation.
As the name implies, BLDC motors do not use brushes
for commutation; instead, they are electronically commutated.
BLDC motors have many advantages over
brushed DC motors and induction motors. A few of
these are:
• Better speed versus torque characteristics
• High dynamic response
• High efficiency
• Long operating life
• Noiseless operation
• Higher speed ranges
Construction & working principle
BLDC motors are a type of synchronous motor. This
means the magnetic field generated by the stator and
the magnetic field generated by the rotor rotate at the
same frequency. BLDC motors do not experience the
“slip” that is normally seen in induction motors.
BLDC motors come in single-phase, 2-phase and
3-phase configurations. Corresponding to its type, the
stator has the same number of windings. Out of these,
3-phase motors are the most popular and widely used.
This application note focuses on 3-phase motors
STATOR
The stator of a BLDC motor consists of stacked steel
laminations with windings placed in the slots that are
axially cut along the inner periphery (as shown in
Figure 3). Traditionally, the stator resembles that of an
induction motor; however, the windings are distributed
in a different manner. Most BLDC motors have three
stator windings connected in star fashion. Each of
these windings are constructed with numerous coils
interconnected to form a winding. One or more coils are
placed in the slots and they are interconnected to make
a winding. Each of these windings are distributed over
the stator periphery to form an even numbers of poles.
There are two types of stator windings variants:
trapezoidal and sinusoidal motors. This differentiation
is made on the basis of the interconnection of coils in
the stator windings to give the different types of back
Electromotive Force (EMF). Refer to the “What is
Back EMF?” section for more information
