A didactic explanation of field oriented systems sensitivity

Almost all papers explain rotor time constant influence in field-oriented systems giving us more and more mathematical expressions without showing explicitly control variables behavior either in steady- and transient-state for tuned and detuned operations. This work intends to mix either mathematical analysis and more exactly simulated and experimental results of this problem to give a didactic explanation for all that are studying this problem. It is known that in field-oriented AC motor control, rotor time constant (T_R) knowledge is crucial to obtain high performance because it is important to know the instantaneous position of the rotor flux that depends on (T_R). Low frequency response, speed oscillations and the loss of input-output torque linearity are the consequences for detuned operation, decreasing motor drive efficiency. In this paper, a nonlinear mathematical model of a three-phase squirrel cage induction motor is linearized under vector control, resulting in a perturbed model that clarifies torque behavior for a rotor time constant decrease or increase in the drive system. Expressions are derived to analyze effects in both steady-state operation and in transient situations. These effects are experimentally verified with a microcomputer controlled induction motor drive system and with simulations of the same system