V/f with stabilizing loops fast response control of Induction Motor (IM) drives

V/f control method is standardly used for general induction motor drives due to its simplicity but, to provide good precision both for rated speed and for low speed applications, such as compressors, pumps, fans, etc., slip compensation current regulators or careful voltage referencing is used. More than that, the standard V/f response in torque (and speed) remains slow and does not handle properly smaller loads at smaller current, in comparison with sensorless field oriented (FOC) or direct torque (DTC) control.Therefore, within the paper, a simplified sensorless control for fast torque (and speed) response based on V/f control, with two correction loops, one loop for the voltage amplitude correction, the other one for the voltage phase correction is proposed. Both digital simulation and experimental results have been conducted to validate the proposed solution.