Industry News

The difference between brushless motor and brushed motor

2023-08-28

A brushed DC motor uses an armature that acts as a bipolar electromagnet. A commutator is a mechanical rotary switch that reverses the direction of the current twice per cycle. In contrast, brushless motors use permanent magnets as their external rotors. And brushless DC motors don't have brushes, which means they require less maintenance and are a little more efficient than brushed motors.



What is a brushed DC motor?

A brushed DC motor has a permanent magnet inside its outer body and a rotating armature inside. Permanent magnets are stationary and are called "stators". The rotating armature contains an electromagnet, known as a "rotor".


In a brushed DC motor, the rotor rotates 180 degrees when a current is applied to the armature. In order to exceed the initial 180 degrees, the magnetic pole of the electromagnet must be flipped. As the rotor rotates, the carbon brush touches the stator and flips the magnetic field, causing the rotor to rotate 360 degrees.



advantage

High starting torque: For applications that require rapid acceleration, high torque brush motors are your choice. For example, in applications such as caravan haulers, high starting torque is essential.


Low cost: Compared with brushless DC motors, the production and purchase costs of brushless DC motors are relatively low.


Suitable for industrial environments: Brush motors are also a popular choice in industrial environments due to their high starting torque.



shortcoming

Increased maintenance risk: Due to the effect of friction on motor carbon brushes, they wear out naturally over time. As a result, brushed motors are more likely to require some kind of maintenance in the form of brush cleaning or replacement.


Lower speed: Despite the high starting torque, brushed motors cannot maintain high speeds. This is because a brush machine running at a consistent high speed causes it to heat up.


What is a brushless DC motor?

Like brushed motors, brushless motors work by changing the polarity of the windings inside the motor. It is essentially an inside-out brushed motor without the need for brushes. In a brushless DC motor, the permanent magnet is installed on the rotor, while the electromagnet is installed on the stator. An electronic speed controller (ESC) adjusts or "reverses" the electric charge of the electromagnet in the stator, allowing the rotor to rotate 360 degrees.



advantage

Long service life: Brushless DC motors do not have brushes, which means they require less maintenance than brushed motors.


Efficiency: No brush means no speed loss, making the brushless DC motor a little more efficient, compared to the brushed motor, usually 85-90% efficiency, 75-80% efficiency.


Quiet operation: Because there is no brush, the brushless motor runs very quietly and runs particularly smoothly. This is especially useful for applications that require such features, such as patient lifts.



shortcoming

A controller is required: A brushless DC motor needs to be connected to an electronic speed control (ESC) to flow current to the electromagnet.


Cost: Brushless DC motors can be more expensive due to the need for a controller.