How to Write your own Flight Controller Software — Part 10

Understanding and Controlling Brushed DC Motors

Drones tend to use either brushed or brushless motors, with the larger drones using the brushless variety while micro or toy drones use brushed. The difference between the two is that brushed motors are mechanically driven and brushless motors are electronically driven. The maximum speed for a permanent-magnet DC motor is 10,000 RPM, while for a brushless DC motor it is > 20,000 RPM.

How to Write your own Flight Controller Software — Part 9

Brushed DC motors are simple to control but have the following disadvantages compared to brushless designs:

• Less efficient
• Run hotter
• Shorter life span
• Require more maintenance
• Can generate more electric noise

DC brushed motor noise can be a source of significant electrical interference. It consists of impulsive and wideband transients repeated at a rate determined by the commutation speed. You can filter out this noise using a capacitor or snubber across the terminals (for differential mode noise) and capacitors from the terminals to earth (for common mode noise).
Brushless DC motors are…