Diffrence between a Variable frequency drive & Servo drive?

Discussion in 'General Electronics Chat' started by ajinkya24, Mar 18, 2012.

  1. ajinkya24

    Thread Starter New Member

    Mar 18, 2012
    As per my knowledge a VFD(variable frequency drive) is used to control speed/velocity of 3 phase induction motor. A variable frequency drive controls the frequency of incoming supply to the motor & hence controls the rpm of motor.
    If i am right, then i have a doubt regarding servo drives.

    1)What is the exact use of servo drive?
    2)What may be the possible applications of same?

    Thank you for your kind support & awaiting your valuable replies..:)
  2. somlioy


    Jul 28, 2010
    You're correct about VFDs.

    jimkeith likes this.
  3. jimkeith

    Well-Known Member

    Oct 26, 2011
    You have it right on VFD drives--I will add that they are used for general purpose motoring applications and may be used with any 3 phase motor--speed regulation is not all that accurate (e.g. 5%) because velocity feedback is generally not used--common power range is up to about 100kW--cost effective drive control

    Servo drives are generally used for precise speed and position control (both while motoring and when stopped)--used for specific applications--generally sold with a special motor--velocity and position feedback is via encoder--high loop gain and often difficult to set up--power range generally does not exceed about 2kW--relatively expensive drive control
  4. GetDeviceInfo

    AAC Fanatic!

    Jun 7, 2009
    consider VFD as a method, then consider servo as an application of that method. Servo is a command/feedback regime, that can employ any and all means of drive technologies. Size or power is not implied.