Design and analysis of a speed controller for fractional‐order‐modeled voltage‐source‐inverter‐fed induction motor drive

Abstract

SummaryThis paper presents the fractional‐order voltage‐source‐inverter‐controlled induction machine (FO‐VSI‐IM) model extraction and integration to improve the closed‐loop speed control performance of variable speed drives. In the operating range of variable speed drive, it is susceptible to load disturbance and speed tracking error. This paper provides the practical approach to obtain the fractional‐order model of VSI‐fed induction motor (IM) drive by using PWM signal injection technique. The injected PWM signals and speed encoder response signals are recorded using the dSPACE 1104 platform. This model is used in constructing the closed‐loop speed control of VSI‐IM with designed integer‐order PI speed controller. The comparative performance is evaluated for FO‐VSI‐IM and integer‐order voltage‐source‐inverter‐controlled induction machine (IO‐VSI‐IM) with feed‐forward gain variations and load disturbances. It is observed that the robust speed tracking capability with the controller designed using the FO‐VSI‐IM model over the controller with IO‐VSI‐IM model under load disturbances. The improvement in speed tracking with less control effort in the FO‐VSI‐IM model is advantageous in field‐oriented control (FOC) drives.