Sensorless field oriented control of five-phase induction machine under open-circuit phase faults

Recently, multiphase machine is promoted to replace three-phase drives in high power safety-critical applications. Among the numerous advantages of multiphase induction machine drives, operation and self-starting under some phases open stand as the most important feature of such drives. With some phases open, optimal current control is proved viable to provide disturbance-free operation with some objective functions and under some operational constraints. Although hysteresis current control was simply employed in the literature with conventional field orientation to control the currents of healthy phases, it is not suitable for high power applications as it usually corresponds to high switching frequency and is susceptible to noise. Alternatively, synchronous reference frame (dq) control is much suitable; however, it requires back and forth transformations with several trigonometric calculations and additional sophistication to the controller with a corresponding intricate tuning process. In this paper, a simple controller using only two PR controllers for each sequence plane, with a total of four PR controllers for five-phase system, is presented. Moreover, a sensorless operation is also provided by estimating machine speed using rotor flux based MRAS speed estimator. The proposed controller is experimentally verified using a prototype 1.5Hp five-phase induction machine.