A Simple Robust Voltage Control of High Power Sensorless Induction Motor Drives With High Start Torque Demand

A simple, robust, high-torque control without a speed sensor, for driving an induction motor with high- and mid-voltage inverters, has been developed. The proposed method is characterized by the unique control of the slip angular frequency of the induction motor, and allows a stable start with high torque. The proposed control method was installed in an H-bridge cascaded inverter, and startup and impact load tests were done with a 3 kV/1500 kW induction motor. Steady operation with a 200% higher starting torque and for a 200% impact load were confirmed. The proposed method can generate a stable start with high torque within the ultralow speed region, and is appropriate for motor drives on industrial equipment such as mixing, extruding, and stirring machines.