Performance Differences Between Brushed and Brushless DC Motors

Brushed motors have a simple structure, long development time, and mature technology

As early as the nineteenth century, when motors were invented, the practical motor that was created was in a brushless form, namely the AC squirrel-cage induction motor. This type of motor was widely used after the advent of AC electricity.

However, asynchronous motors have many insurmountable defects, leading to slow technological development. Specifically, brushless DC motors have been unable to be commercially viable for a long time. With the rapid advancement in electronic technology, brushless DC motors have only recently started being used commercially; in essence, they still fall within the AC motor category.

Not long after the invention of brushless motors, people invented brushed DC motors. Due to the simple structure of brushed DC motors, they are easy to produce and process, convenient to maintain, and easy to control. DC motors also have quick response times, large starting torque, and the ability to provide rated torque from zero to rated speed. Therefore, they have been widely used since their inception.

Brushed DC motors have a fast response speed and large starting torque

Brushed DC motors respond quickly, have large starting torque, smooth speed transitions, and almost no noticeable vibration from zero to maximum speed. They can drive larger loads at startup. In contrast, brushless motors have high starting resistance (inductive reactance), thus a lower power factor and relatively smaller starting torque. They produce a buzzing sound with strong vibrations during startup and can only drive smaller loads.

Brushed DC motors run smoothly with good starting and braking effects

Brushed motors adjust speed and voltage for control, leading to stable starting and braking. They also run smoothly at constant speeds. Brushless motors typically use digital frequency conversion control, converting AC to DC and then back to AC. Speed is controlled by frequency changes. Therefore, brushless DC motors tend to be unstable with significant vibrations during starting and braking and only stabilize at constant speeds.

No brushes, low interference

Brushless DC motors eliminate brushes, which directly reduces the electric sparks generated by brushed motors, significantly decreasing the interference with remote radio equipment.

Low noise, smooth operation

Without brushes, brushless DC motors have greatly reduced friction during operation, making them run smoothly and more quietly. This advantage greatly supports the stability of modeled operations.

Long lifespan, low maintenance cost

With the absence of brushes, the primary wear in brushless DC motors occurs in the bearings. From a mechanical perspective, brushless DC motors are almost maintenance-free. When necessary, only some dust removal maintenance is required.