AC Drive or alternative current drive is a type of electrical drive that is designed for precise control of AC motor speed. Controlling the motor speed is the primary function of AC drives. These are particularly used for three phase induction motors as such motors are predominantly used in a number of industries.
Types and Features of AC Drives
most common types of AC Drives are:
Induction AC Drive – this
motor drive induces current into the rotor winding in the absence of any
physical connection with the stator windings. This type of AD drive is
adaptable to different environments and designed for considerable power and
variable speed control. In induction motors, there is built-in mechanism to
track loss of exact speed.
Synchronous AC drive – this
type of motor functions on constant speed to the maximum load. The rotor speed
is equivalent to the speed of the stator’s rotating magnetic field. Reluctance
and permanent magnet are two main types of synchronous motors and such motors
are used where the exact speed of a drive should be sustained.
Sensorless vector drives – these
drives press into action autonomous control of both frequency and voltage supplied
to the motor for optimum speed control. This type of AC drive is designed for
low-speed torque output when coming near to DC motors. In this drive,
sensorless denotes that no feedback sensor like a resolver or encoder is
Servo motor drives – this type is
typically everlasting magnet synchronous motor which can be characterized by
low torque-to-inertia ratio for increased acceleration ratings. The motor in
this drive is controlled by instructions coming from a PLC (programmable logic
controller). It performs feedback control by receiving signals from an encoder.