In this paper, we present a new approach to sliding mode control for i
nduction motors. The novelty is in the sliding variable formulation. U
nlike previous approaches, where a linear combination of system states
is used, our definition is nonlinear and dynamic and, when the system
is in sliding mode, an adaptive reference signal is realized which ca
n explicitly counteract mismatched parametric uncertainties. This meth
od is robust to parameter variations and the stability analysis is sim
ple. Full state measurements are needed for implementation. Load torqu
e and rotor resistance can be unknown but bounded.