What is a Brushless DC Motor and How Does It Work?

July 1, 2019

Author: Romy Fernandis

Brushless DC Motors (BLDC-Motoren)are mostly found in industrial applications all over the world. At the most fundamental level, we have brushed and brushless motors, DC, and AC motors. Note that, just as the name suggests, brushless DC motors (BLDC-Motoren), do not have brushes and use a DC current. These motors come with many specific advantages over other types of electrical motors.

How a Brushless DC Motor Works

For us to understand how a brushless DC motor works, it is best to first peruse through its predecessor, the brushed DC motor. This kind of engine has permanent magnets on the outside and a spinning armature based on the inside. These stationary and permanent magnets are what we call the stator. While the armature, which is the rotating part, containing an electromagnet, is called the rotor.

The rotors of a brushed DC motor spin at 180-degrees when an electric current passes through to the armature. Suppose you go further, the electromagnetic field will flip. The brushes, operating as the rotor spins, come into contact with the stator, hence, flipping the magnetic field, allowing the rotor to rotate a full 360-degrees.Thus, a brushless DC motor is importantly flipped inside out, eliminating the brushes needed to turn the electromagnetic field. When it comes to Brushless Motors (BürstenloseMotoren), the everlasting magnets are usually found on the rotor, while the electromagnets are located on the stator. For the stator to rotate the rotor at full 360-degrees, a computer has to charge the electromagnets.

Brushed and Brushless DC Motor Differences

Brushed DC motors mainly operate using an iron core, commutator, and wire coils mounted on the same shaft. These elements are thus made of metal, causing them to become burdensome, with a likelihood of producing high rotor inertia. This is not a desirable outcome for industrial applications. To reduce rotor inertia, manufacturers have been able to come up with BLDC motors. By using permanent magnets mounted on top of the rotor and electronic commutation, which has in turn replaced mechanical compensation.

Advantages of Brushless DC Motors:

High Torque at Low Speeds

Since brushless BLDC Motors can develop high torque with good speed response, they are ideal for those applications that need variations in speeds. Examples of these are pumps and fans. Their motors can achieve differences in speed in response to operating in an electromechanical system, in conjunction with a rotor position feedback sensor and electronic motor controller. BLDC motors are excellent choices for applications, which require constant-torque loads. Such machinery includes Cranes, extruders, and conveyor belts.

Durability and Simplicity of Routine service

In addition to not having brushes, BLDC motors also do not have a mechanical commentator. This means that there are fewer parts that will wear out, break, need replacing or require maintenance. They are also more efficient, reliable and durable. Some custom made BLDC motors even have a lifespan of 30,000 hours and beyond. They also operate with less noise due to the enclosure of its internal features.

Positioning and Actuation Systems

Regarding industrial applications, BLDC motors are commonly used in variable speed, servo, and actuation, including positioning applications, where stable operations and purposes of precise motion control are imperative.