Squirrel-cage induction motors (IM) are the workhorse of industries for variable speed

applications in a wide power range that covers from fractional watt to megawatts. However,

the torque and speed control of these motors is difficult because of their nonlinear and

complex structure. In the past five decades, a lot of advanced control schemes for IM drive

appeared. First, in the 1960’s, the principle of speed control was based on an IM model

considered just for steady state. Therefore, the so-called “scalar control methods” cannot