In this paper vector control with variable frequency drive used to
apply speed control of a three-phase AC Asynchronous and induction machines.
The flux and torque references used to obtain the current components.
Proportional-Integral controllers are used to keeping the measured current
components at their reference values. The stator voltage references are the
output of the PI current controllers. High-performance with the smooth
operation is obtained using the proposed method. The differences can be seen in
behavior dynamic state. When the motor is rotating at full speed with a full
load,it reaches good current waveforms very easily due to the independent PI
control of torque and magnitude of flux. In high and sudden variations of the
reference input, the direct command is more efficient and less demanding for
the equipment. The expressions of the fundamental variables (speed, torque,
flux) and equivalent phase circuit of the machine will be reviewed.