A simple and low-cost method for three-phase induction motor control in high-speed applications

This paper presents a simple method for speed control of induction motors on the basis of direct control of the stator flux modulus. The proposed method needs neither mechanical sensor nor current transducers, so it can be compared with “Variable Voltage Variable Frequency (v/f)” method. High-speed operation of induction motor controlled by the proposed method is compared with that of v/f method that leads to the fact that in addition to control of motor dynamic behavior, the proposed method uses DC-link voltage in a more efficient way. In the stator flux modulus control, the amplitude of electromagnetic torque ripple and average switching frequency are computable and analytical formulas for calculation of them are derived. The performance of proposed method and accuracy of presented formulas are validated in MATLAB/Simulink.