This paper presents a unified approach to deal with
sliding mode controllers used for induction motor drives. The
study digs deep to identify matched and unmatched disturbances
and derive conditions to satisfactorily reject the same. The
investigation reveals fundamental limitations of hysteresis (first
order sliding mode) controllers those can be overcome by higher
order controllers. Second order sliding mode controllers are
investigated to achieve disturbance rejection and chattering free
performance. It is shown that the drive with second order sliding
mode controllers maintains constant switching frequency and
decoupling between torque and flux simultaneously in the face of
sudden speed, load, or parameter variations. Also, it is shown that
the dynamic performance can be drastically improved at higher
sampling frequencies keeping the switching frequency constant.
Extensive simulations are carried out in Matlab/Simulink. Imple-
mentation of such a drive becomes feasible with low cost FPGAs
due to their inherent parallel processing capability. A vector
controlled induction motor drive is developed and the controller
is implemented using FPGA to corroborate the simulation results
through experimentations.