Speed-sensorless stator-flux-oriented control of induction motor drives in traction

Indirect Stator-Quantities Control (ISC) combines the principle of stator-flux-orientation proven successful in Direct Self Control (DSC) with Pulse-Width Modulation (PWM). High torque dynamics and robust behaviour against input voltage disturbance are achieved in the whole operation range including field-weakening. After careful correction of inverter-voltage errors and dc portions in the stator fluxes and currents not necessary for the actual operation point the difference of the stator-current space vectors in the machine and in the controlled model is employed for speed and stator resistance estimation, allowing to dispense with speed sensors. A special flux management allows infinitely slow change between driving and braking.