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Electrical motors contain a part which is known as brushes, these brushes act as a contact between the power supply and the rotor. While rotating at high-speed, rotors can damage the brushes, so after a limited amount of use, they should be replaced.
This phenomenon caused unnecessary costs for usage of motors. So, inventors came up with a fascinating solution for this problem which is Brush Less DC motor or BLDC Motor. They are also known as electronically commutated motor or ECMs.
Why is BLDC Motor a revolution?
The fundamental structure of a motor had brushes. Brushed DC motors were invented in the 19th century. On the other hand, BLDC Motor technology is recently developed with the advent better permanent magnet materials and more advanced Solid-State Electronics.
Structure of a Brushed motor: - Any electric motor creates its torque through the rotating magnetic fields between the rotor which is the rotating part and the stator which is the stationary part.
The magnetic fluxes are created by supplying current in the wires wound on the iron core which acts as electromagnets.
But the problem arises when the rotor traverses an angular distance of 180o the polarity of the poles gets reversed. So, with the same direction of the current rotor portion faces a same amount of torque in the opposite direction i.e. the total torque in a full cycle is zero and the motor stops working.
The solution given in the 19th century was to reverse the polarity of the current with every 180o turn of the rotor. This was achieved by the element known as a commutator.
Problems aroused with the brushes: - Commutator is the motor’s shaft which contained certain separated divisions. The divisions were connected windings on the rotor. Brushes were the stationary contacts squashed against the commutator.
This provides a sliding electrical connection with consecutive. Due to this set up, the problem of zero torque was nullified, as on every successive 180o turn, the commutator reversed the current polarity automatically.
But this technique came at several costs which are as follows –
1. There is a friction between the brushes and the commutator slices which causes a noteworthy amount of power loss through heat. These losses are more prominent in low power motors.
2. Brushes are made of soft materials like graphite. Eventually, they grind down due to the friction, so they needed to be frequently replaced which is tough for conserved uses viz. Hard disk motors.
3. The frequent rapid changing of the current direction through the inductive windings can cause flickers in the contact site these can be dangerous in inflammable environments. Not only that the noise created can cause EM interference in neighboring microelectronic circuits.
Replacement of the brush technology: - As mentioned above the problems with brushed motor necessitated the creation of BLDC Motor. In BLDC Motor an electronic servo system does the job of the commutator contacts. A sensor is used for calculating the angle at which the rotor is at the instant. Depending upon the angle of the rotor sensor control the current’s either direction or supply to keep the polarity same as before through the whole operation. This technology eliminates the use of brushes in electrical motors completely. Not only has that it prolonged the working life of the motor as they are not needed to be replaced due to worn out brushes.
Advantages of BLDC Motor over brushed motors
One major advantage has stated above. The rest of them are as follows –
1. BLDC Motors are highly competent than brushed DC motors.
2. They are less vulnerable to mechanical damage which prolongs their lifetime.
3. In usual BLDC Motors, the rotor made of permanent magnets revolves about an attached armature. This helps to get rid of problems engaged with moving armature.
4. An electronic controller is swapped in for the tasks of the brushes which make the process more enriched.
5. BLDC Motors provide higher torque to weight ratio, i.e., the same size brushed motor will be defeated by the same size BLDC Motor in comparison of better torque generation. Not only for the size but also for the same amount of power consumed BLDC Motors can generate more torque than brushed motors.
6. Due to their construction, BLDC Motors are more reliable than brushed motors. For example, brushed motors can't be used in an explosive because the friction between the brushes and the rotating plane can cause a spark which can lead to fatal accidents. But BLDC Motors can be used in the same environment without the said concern.
7. BLDC Motors cause less noise than brushed motors. Not only has its treat to the ears but this silent operation reduced the chances of any electromagnetic interference in the neighboring electronic circuits.
8. BLDC Motors can be and are used in microcontrollers and microprocessors of the computers. Apparently, commutation with electronic controller offers greater flexibility and abilities like micro-stepped operations, slow and superior motion control, etc which were never possible with brushed DC motors.
9. Conversion of electrical energy into mechanical energy, which is motors primary work, is found to be more efficient in case of BLDC Motor than brushed DC motors.
After all the facts stated anyone with a clear understanding of reality could see why BLDC Motor technology is considered as the advanced and more efficient technology.
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