Sensorless vector controllers for induction motor drives

The development and implementation of sensorless vector controllers based on stator flux-oriented control (SFOC) and rotor flux-oriented control (RFOC) are presented. For flux estimation, instead of measuring phase voltages directly or estimating phase voltages indirectly using switching states and DC link voltage, the voltage command for inverter control is used and therefore only current sensors are required. The effect of dead time on speed control at low speed range is highlighted and the details of dead time compensation are presented. Simulation results from a model-based computer-aided design approach using Simulink, and experimental results are presented to confirm the theoretical analysis and hardware design.