Accurate, precise and rapid
positioning is the basic concept of the servo,
variable frequency is a necessary internal links, and there is also variable
frequency in servo motor
controller (to be variable speed). However, the current loop
servo-loop speed or position control loop is closed to control, this is a big
difference. In addition, construction of the servo motor
and General Motors is different, it need to meet the requirement
of fast response and accurate positioning. AC servos in circulation now mostly
are permanent magnet synchronous servo motor, but the motor was limited by the
process, it is highly difficult to make large power motor, the power more than
a dozen KW synchronous servo’s price is expensive, so in the case of field application,
AC induction servo usually will replace servo motor.