A brushless DC motor or BLDC motor is known to be electrically commuted DC motor that doesn’t compromise of brushes. In general, such motors comprise permanent magnets present on the outside of the structure. This magnet gives the torque speed characteristic to the motor that actually mimics DC motor. By using this magnet and sensor, it is easy to detect the rotor position.
Is permanent magnet ideal for BLDC?
The BLDC with permanent magnet generally comprises of two essential parts, rotor, and stator. The magnet is present on the rotor along with the rotor position sensor. The sensor is required for offering information regarding the position of the shaft. The signal of shaft position is further sent to the electronic commutator.
There are lots of advantages to using a permanent magnet. Some of them are –
- No presence of mechanical commutator.
- Speed can be controlled without any trouble.
- It is possible to make regenerative braking.
- Excellent for giving precise control.
- Use the Pulse Width Modulation method for producing fewer harmonics, and the generation of torque is more.
- Require less power to start.
- In a smaller size, it provides high speed.
- The production of heat is very less.
- Also, bearing stress is low.
- Improve the efficiency of the motor.
- Presence of low thermal resistance.
- If there are no brushes, it prevents the formation of dust.
- The operation is very quiet.
These motors with permanent magnets are used for automotive applications, textile industries, computers, robotics, and small appliances.
How BLDC with permanent magnet works?
The permanent magnet or china magnet works wonder in BLDC. The principle of its working is very simple. Whenever DC supply is given to the motor, the winding causes the formation of current. This current is further distributed in the stator armature and is dependent on the rotor position.
In the next step, the MMF perpendicular is setup to the permanent magnet. After this, the armature conductor will start experiencing a force. This force is responsible for developing a torque inside the rotor. In case this torque goes above opposing frictional and load torque, then the motor will start automatically.
