Abstract:
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 on the face of sudden speed, load,
or parameter variations. Also, it is shown that the dynamic performance
can be improved further at higher sampling frequencies
keeping the switching frequency constant. Extensive simulations
are carried out in MATLAB/SIMULINK. Implementation of such
a drive becomes feasible with low cost field programmable gate arrays
(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.
