Scalar speed control of induction motor with curve-fitting method

Abstract

Induction Motors (IM) are known to lag behind the rated speed when operating at different loads. In this context, controllers gain importance. This problem has attracted the attention of many scientists from past to present. In this study, it was carried out to increase the speed control performance of IM. Scalar Control (SC) method is used in the speed control of IM. Variable Frequency Control (VFC) technique was preferred in SC. Thus, frequency change will be performed for the IM, which must operate at different loads, to reach the rated speed. In the study, some Curve Fitting (CF) methods included in numerical solution methods are used to provide frequency variation. These are the Polynomial, Fourier and Gaussian methods. These methods calculate the frequency required for the IM operating at different loads to operate at rated speed and transmit it to the drive. The study has been tested in Matlab/Simulink program. The results obtained from the tests showed that the proposed techniques respond quickly to different speed and load changes, provide a more precise and stable speed control and produce successful results. Among the methods producing similar results, Polynomial curve fitting (PC_IM) performed the best performance. The obtained results show that curve fitting methods can be used as direct controller.