A control method of induction motor fed by current regulator pulse width
modulation inverter is presented to obtain fast dynamic response. This proposed
method is based on the closed-loop control of the torque angle and has the
merits of being simple in implementation and insensitive to rotor resistance
variation. The proposed scheme utilizes the inverter frequency as the necessary
system stabilizing, while the current amplitude merely adjusts the motor steady
state flux level. The stabilization is achieved by regulating the phase angle
between stator current and rotor flux. The design of proposed scheme is
introduced. Speed controller using synchronous reference frame PI regulator is
employed as an outer loop. Moreover, another synchronous reference frame PI
regulator is employed as inner loop to control the tangent of torque angle. An
analytical method for obtaining the rotor speed based on model reference
adaptive system without using stator and rotor resistance is proposed. By using
this method, speed sensor-less closed-loop torque angle control with no
influence of the stator and rotor resistance variations obtained. Also, this
proposed method does not require any integrators in its algorithm. In this paper,
the control scheme was successfdly implemented and tested in laboratory using
a high-speed signal processor (DSP). The experimental results validate the
theoretical predictions with different dynamic operating conditions.