BLDC Motor Basics.Part 2

Greetings from team!

In the 1st part of our BLDC Motor Basics post we promised you to provide information about the BLDC motor principle of work,  about improving the performance of it and the BLDC motor types. We appreciate our readers and we keep our promises, so here it is – read, learn and enjoy 😉

Working principle: basic interaction between a permanent magnet(rotor) and an electromagnet(stator).

For simplicity,

Consider three stator coil winding arrangements A, B and C.
When coil A is given a dc supply, it gets energized and becomes an electromagnet.

The opposite pole of the rotor gets attracted to the stator(opposite poles attract). As a result, the rotor pole moves near the energized stator.

As the rotor nears the coil A, coil B of the stator is energized. Similarly, as the rotor nears coil B, coil C is energized. After that, coil A is energized with opposite polarity.

This process is repeated, and the rotor continues to rotate.

Improving the performance of the BLDC motor:

Problem –  as seen above, only one coil is energized at an instant. The 2 inactive coils greatly reduce the power output of the motor.

In order to avoid that, energize coil B with the same polarity as coil A, when the rotor is in the position with coil A.

In this way, the combined effect will push the rotor and produce more torque and power output from the motor. The combined force also makes sure that a BLDC has a beautiful, constant torque nature.

To energize the 2 coils at the same time, the free ends of the coils are connected together.

Electronic controller unit:

An ECU is used in a BLDC motor to determine the position of the rotor and to energize the coils accordingly.

The Hall-effect sensor is used to sense the position of the rotor.

This sensor gives information to the controller, which energizes the stator coils accordingly.

Types of BLDC Motor:


In the Out-Runner type, the magnets are placed on the outside of the stator, as shown in the fig. below.

Compared to the in-runner type bldc motor, the out-runner has more mechanical advantages.It has comparatively more torque.

Comparatively, It can swing heavier props.

 2. In-Runner:

In the In-Runner type of motor, the magnets are placed on the inside of the stator, as shown in the fig. below.

Comparatively, it runs on high RMP.

Inrunner and Outrunner BLDC types of motor
BLDC Motor types


Advantages of a BLDC motor:

  • Better speed v/s torque characteristics
  • High dynamic response
  • High efficiency
  • Long operating life due to lack of electrical and frictional losses
  • Noiseless operation
  • Higher speed ranges

Applications of BLDC Motor:

  • Transportation
  • Heating and ventilation
  • Industrial engineering
  • Model engineering

So now you know basic motor information – we created it in short form so anytime when you’ll forget something it’ll be easy for you to open our post and check it.

For more informative posts and our product reviews follow us and check our social media and website 😉

Here is to your prosperity,

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.