Three-Phase Inverter-Fed Induction Motor Drives

Induction motors (IM) find applications in the industries and electric vehicles. To study the variations in stator and rotor currents, rotor torque and speed when the externally applied mechanical load suddenly changes or when the input frequency deviates from the original value when fed by power electronic converter, dq0-axis voltage-current and flux linkage equations are used to develop the dynamic model. Interactive model for three-phase IM using flux linkage equations in state space is presented here. This is followed by model for three-phase IM fed by (a) sine pulse width modulation (PWM), (b) third harmonic injection PWM, (c) clipped sine PWM and (d) multicarrier sine level shift PWM diode clamped three-level inverters. Also case studies of models for three-phase IM fed by space vector PWM (SVPWM) inverter and vector controlled three-phase IM fed by SVPWM inverter are presented. Also models for direct torque control (DTC) of three-phase IM drive fed by SVPWM two-level inverter using classical switching table in the speed control and torque control mode are presented. Case studies are presented for the DTC of three-phase IM fed by SVPWM inverter using modified switching table in the speed control and torque control mode.