Essentials of Brushless DC Motor

All DC motors use wound coils of wire to create a magnetic field. In brushed motors, these wires are not fixed but are free to rotate, driving the rotor shaft. The part that remains stationary is called the stator, where magnets are positioned on the inner surface.

The BLDC motor, short for Brushless DC Motor (also known as an Electronically Commutated Motor, or ECM/EC), eliminates the need for brushes. Instead, an electronic controller is used to switch DC current to the windings of the motor, which in turn rotates the rotor. This controller adjusts the phase and amplitude of the current to control the motor's speed and torque.

The controller system in a BLDC motor functions similarly to the mechanical commutator and brushes used in traditional motors, but with the added advantage of greater efficiency and less wear and tear due to the absence of brushes.

History:

To understand the origins of brushless DC motors, we must trace back to the early interventions by Mr. Est Weer in 1856. These early inventions have undergone numerous developments over time.

The journey began with the invention of the power dimmer, which had the ability to convert alternating current (AC) into direct current (DC). This foundational technology paved the way for future innovations in motor technology.

In 2003, Makita became the first company to incorporate brushless DC motors into their power tools. Initially, these motors were assembled exclusively for the defense and aerospace industries. However, over time, in 2009, Makita released the first brushless DC motor featuring three impact drivers for commercial use.

The concept and theory behind these motors were first presented in an AIEE (American Institute of Electrical Engineers) paper titled "DC Machine with Solid-State Commutation." This paper laid the groundwork for understanding the efficiency and advantages of brushless motors.

In 1962, T.G. Wilson and P.H. Trickey published a landmark article discussing brushless motors operating on direct current. The major innovation highlighted in their work was the absence of physical switches for the transmission of energy, marking a significant evolution in motor technology that would lead to the widespread adoption of brushless DC motors in various industries.

Advantages: 

DC motors offer several advantages that make them highly useful in various applications. They have a high power-to-weight ratio, allowing them to deliver significant power while being relatively lightweight. They also provide high speed with instantaneous control over speed (RPM), making them ideal for applications requiring precise speed adjustments. These motors are known for their high efficiency and durability, which contributes to their long-lasting performance. Additionally, low maintenance costs make them cost-effective over time.

DC motors are widely used in computer peripherals, such as disk drives and printers, and have revolutionized designs by replacing old rubber belts with direct drive systems. They contribute to increased reliability and reduced noise pollution due to the elimination of the mechanical components that would traditionally produce noise. Another significant advantage is the elimination of sparks from the commutator, which further enhances the motor's reliability and safety.

Disadvantages:

Despite their many benefits, DC motors also have some disadvantages, particularly related to the commutator. One disadvantage is that friction in the brushes and commutator leads to low power output. The brushes used in DC motors are relatively soft, and due to constant friction, they can become damaged over time, requiring replacement. This wear and tear can make them unsuitable for applications like hard disk motors or other precision tasks.

Another disadvantage is the electric resistance caused by the sliding brushes, which results in a phenomenon known as brush drop. This drop in voltage can lead to energy loss and reduced efficiency. Additionally, the repetition of abrupt current switching in the motor causes sparking at the commutator, which can be hazardous, particularly in explosive environments, where it poses a fire hazard. These issues highlight the challenges associated with traditional brushed DC motors.

Purpose: 

During manufacturing the brushless DC motors are basically used for motion control, acquisition and positioning of whole system.

Construction:

The construction is similar to permanent Magnet, but it has something new that it might use neodymium Magnet which will work in two ways. One they might be out runner’s means that stator in motor is surrounded by rotors, or secondly it might be in ruuner’s in which the rotors are surrounded by stators.

The third opinion option can also be available when the rotors and stators and flat and parallel with each other which is called axial.

Variations in construction:

Brushless motors can be constructed in various ways. Permanent Magnets are part of it. Three different stators are winded across the rotor, which the relationship in reverse way in between coil and magnets. Out runners mostly have more poles which are set up in triplet’s position in order to maintain the group of windings. In all Brushless DC motors, the coils used are stationary.

The delta connection is installed which connects all the three windings.

Usage in transport:

They are found in different hybrid, electric and main transport vehicles. They can also be used in electric bicycles which are located in wheel hub where the stators are fixed to axle. In exactly the same way they are installed in scoters.

They have expected life of 10,000 hours.

Difference between brushed and Brushless motors:

People often get confused in both of them because it has very minute difference in it. Brushed motors basically are driven through mechanical force while Brushless DC motors through electrically force.

In brushed motors, it contains stationary part in permanent Magnet. Stator is stationary part in it. When continuously the flipping of polarity happens it cause the spinning motion. This design is very simple but it contains some disadvantages like they are less efficient, hotter, contains shorter life span and requires more maintenance.

Whereas in Brushless DC motors, the whole phenomenon got exchanged. Here the rotors have permanent Magnet and stators create mechanical. Similarly they have also some disadvantages which are; they require more electronic controller, they are more expensive and complex to understand

Which one is better?

Both have significantly working better and giving proper results. The betterment of both depends on the cost of production. In both of them the brushes motors are less costly and are produced in mass level whether as the brushless motors are expensive. Despite of their low cost some other benefits of brushed motors are that they are simple to operate, reliable and are easily controlled.

Conclusion:

If someone is interested in wholesale purchase of any kind of DC or AC motors they can shop it easily at Mag spring. They accept all kinds of order weather it is for commercial use or personal use. Their catalogue is available at their website

As the cost of Brushless DC motors and their associated items are getting decreasing day by day, that’s why they are finding their way to excel in many different applications or in other fields.

There is one other benefit of using Brushless DC motors as compared to brushed one; feedback. Obviously one will always require feedback in order to know his performance. From rotation data, one can check his performance which exists in Brushless motors.