| Abstract |
An adaptive non-linear state feedback position
control scheme of a voltage-fed induction motor has been
developed in which the control of torque and flux is decoupled.
The inputs to the control algorithm are the reference position,
the reference flux, the measured stator currents, the measured
rotor position, the estimated rotor flux and estimates of the rotor
resistance, stator resistance and load torque, which may vary
during operation. The controller outputs are the reference stator
voltages in rotor flux rotating reference frame. Accurate
knowledge of rotor flux and machine parameters is the key
factor in obtaining high performance and high efficiency
induction motor drive. The rotor flux is estimated using the
induction motor rotor circuit model. Although the estimated
rotor flux is insensitive to stator resistance variation it does
depend on rotor resistance. A stable Model Reference Adaptive
System (MRAS) rotor resistance estimator insensitive to stator
resistance variation has been designed. Stable load torque,
motor speed and stator resistance MRAS estimators have also
been developed. These estimators have been developed to
constitute a Multi-Input-Multi-Output (MIMO) decoupled
cascade structure control system. This simplifies the design
problem of the estimators for stable operation from a MIMO
design problem to a Single-Input-Single-Output (SISO) design
problem. The continuous, adaptive update of the machine
parameters and load torque ensures accurate flux estimation
and high performance operation. Simulation and experimental
results are presented to verify the stability of the induction motor
drive in various operating modes. |
