Direct current (dc) motors have variable characteristics and are used extensively in variable-speed drives. Dc motors can provide a
high starting torque and it is also possible to obtain speed control over a wide range. The methods of speed control are normally
simpler and less expensive than those of ac drives. Dc motors play a significant role in modern industrial drives. Both series and
separately excited dc motors are normally used in variable-speed drives, but series motors are traditionally employed for traction
applications. Due to commutators, dc motors are not suitable for very highspeed applications and require more maintenance than do ac
motors. With the recent advancements in power conversions, control techniques, and microcomputers, the ac motor drives are
becoming increasingly competitive with dc motor drives. Although the future trend is toward ac drives, dc drives are currently used in
many industries. It
- Enseignant: ala houam