What are the pros and cons of a brushed motor?

2017-09-06

What are the pros and cons of a brushed motor?

Brushed Motor Pros
  • Two wire control
  • Some are rebuildable for extended life
  • Low cost of construction
  • Simple and inexpensive control
  • No controller is required for fixed speeds
  • Operates in extreme environments due to lack of electronics
Brushed Motor Cons
  • Periodic maintenance is required
  • Speed/torque is moderately flat. At higher speeds, brush friction increases, thus reducing useful torque
  • Poor heat dissipation due to internal rotor contsruction
  • Higher rotor inertia limits the dynamic characteristics
  • Lower speed range due to mechanical limitations on the brushes
  • Brush arcing will generate noise causing electrical magnetic interference (EMI)
Brushless Motor Pros
  • Electronic commutation based on position sensors vs mechanical switch for brushed
  • Less maintenance due to absence of brushes
  • Speed/Torque- flat, enables operation at all speeds with rated load
  • High efficiency, no voltage drop across brushes
  • High output power to size ratio.
  • Reduced size due to superior thermal characteristics. Because the windings are connected to the case the heat disipation is better
  • Higher speed range - no mechanical limitation imposed by brushes/commutator
  • Low electric noise generation (EMI)
Brushless Motor Cons
  • Higher cost of construction
  • Control is complex and expensive
  • Electric controller(ESC) is required to keep the motor running which is sometimes more expensive than the motor.