Sensorless speed control of a five‐phase induction machine under open‐phase condition

Abstract

Recently, multiphase machines have been promoted as competitors to their three‐phase counterparts in high‐power safety‐critical drive applications. Among numerous advantages of multiphase induction machine (IM) drives, self‐starting and operation under open phase(s) stand as the most salient features. With open phase(s), optimal current control provides disturbance‐ free operation given a set of objective functions. Although hysteresis current control was merely employed in the literature as it offers a simple controller structure to control the remaining healthy phases, it is not suitable for high‐power applications. In the literature, multiple synchronous reference frame (dq) control can be an alternative; however, it requires back and forth transformations with several calculations and additional sophistication. In this paper, a simple technique employing adaptive proportional resonant (PR) current controllers is presented to control a five‐phase IM under open‐phase conditions. Results for both volt/hertz (V/f) and field oriented control (FOC) systems are presented. Moreover, sensorless operation under fault condition is also demonstrated by estimating the machine speed using a rotor flux‐based model reference adaptive system (MRAS) speed estimator. The proposed controllers are experimentally verified and compared. Although FOC provides better dynamic performance, V/f control offers a simpler control structure and a lower number of PR controllers.