Universal Motor  Favorite


The stator and rotor windings of the motor are connected in series through the rotor commutator. Therefore the universal motor is also known as an AC series motor or an AC commutator motor. The universal motor can be controlled either as a phase-angle drive or as a chopper drive.


  • Substitutes another field winding for DC motor’s permanent magnets
  • Can be driven by AC or DC (hence "universal")
  • High construction complexity
  • Low reliability
  • Low efficiency
  • Poor EMI (brushes create sparks and ozone)
  • Driven by rheostat, chopper or phase angle (SCR or Triac) controllers
  • Some degree of sensorless speed control possible
  • Good power to weight ratio