Servo drives and power electronic controllers

Dc and ac servo drives

Most commonly used servo drives in industries are DC Servo drives 

Types:-

1. DC Servo drives
2. Brush less DC (BLDC) drives
3. 3 – Phase induction motor base servo drives
4. Permanent magnet synchronous (PMS) base servo drives

Servo drives are speed or position control drives meting specification on dynamic and steady-state response.the counter part is adjustable speed drives which care only the steady-state behavior. Servo drives is need lower moment of inertia. Lower moment of inertia for facility to fast acceleration/declaration and reversing. They must process high torque capability to support fast motion.

Volume of the rotor is respective how its peak torque for given volume. The radius and axial length must be selected to be inertia requirement subject to other design construction the most flexible motor in the respect is the BLDC motor. Permanent magnet synchronous (PMSM) is also good on this. 

DC Servo drives

Presently day DC Servo drives Are build around the field permanent magnet DC motor all separately excited DC motor. They are both motors are similar in many expect. Permanent magnet motor is excited by permanent magnet, separately excited DC motor separate current supply to its field winding the most attractive Period of the DC Servo drives is the External accuracy of the controls and simplicity of the control. No others can do this level of performance with simple control 

DC motor is not without drawback its mechanical commutator triggered  a series of drawback such as sparking, noice, EMI, power losses, need of frequently cleaning and restriction of upper speed and Power. Still DC Servo drives survive during strong control features stay before.