16-05-2013, 03:26 PM
3 phase Induction motor speed control by v/f method
3 phase Induction.pptx (Size: 1.56 MB / Downloads: 121)
Introduction
In industry traditionally AC machines have been used in constant speed applications, whereas DC machines were preferred for variable speed drives. DC machines have the disadvantages of higher cost and maintenance problems with commutators and brushes. Commutators and brushes do not permit a machine to operate in dirty and explosive environment.
An AC machine overcomes the drawback of DC machines. Although currently, the majority of variable speed drive applications use DC machines, they are progressively being replaced by AC drives.
While there are different methods of speed control of induction motor,Variable Voltage Variable Frequency (VVVF) or V/F is the most common method of speed control. This method is most suitable for applications without position control requirements or the need for high accuracy of speed control.
Advantages
The speed of three-phase induction motor is
being controlled by varying supply voltage and
frequency with constant (V/F) ratio.
It is simple, economic to easier to design and implement in open loop.