
21-6 Power Electronics and Motor Drives
e model thus obtained (Equations 21.14 through 21.18) corresponds directly to the two-phase
motor description and can be used to build a simulation model of the IM. It can be seen from Figure
21.1 that the cage-rotor IM, as a control plant, has a coupled nonlinear dynamic structure, and two of
the state variables (rotor currents and uxes) are not measurable. Moreover, IM resistances and induc-
tances vary considerably with a signicant impact on both steady-state and dynamic performances.
Case 2: Current-Controlled IM Represented in Synchronous Coordinates (d, q)
Let us adopt a coordinate system d − q