###### Abstract  
This paper aims to develop an innovative sensorless control approach for a five-phase induction motor (IM) drive. The operation principle of the sensorless scheme is based on the sliding mode theory, within which a sliding mode observer (SMO) estimates the speed and rotor resistance simultaneously. The operation methodology of the proposed control technique is formulated using the mathematical model of the machine and the two-time-scale approach. The observation technique offers a simple and robust solution of speed and rotor resistance estimation for the sensorless control approach of the multiphase drive. The paper considers the five-phase induction motor (IM) as a case study; however, the proposed control algorithm can be employed by different types of multiphase machines. To test the applicability of the proposed sensorless control approach, the drive performance is firstly validated using MATLAB/Simulink-based simulation. Then, the simulation results are verified using real-time simulation and experimentally using TMS320C32 DSP-based control board. The obtained results confirm and validate the ability of the proposed control procedure in achieving a robust dynamic performance of the drive against the system uncertainties such as parameter variation. Keywords:multiphase machine; five-phase IM; sliding mode observer; sensorless operation; experimental validation +
Footnote †: journal: Applied Soft  
of the multiphase machine that is considered the most desired requirement nowadays, especially for high power applications. High-performance control of induction motors requires precise knowledge of the rotor position. This information can be provided by mechanical sensors, i.e., dynamo tachometer, digital incremental encoder, etc. However, using mechanical sensors introduces several drawbacks. These drawbacks include the increase of the volume, the overall cost of the system, and also the reduction of the system reliability. In addition, mechanical sensors require a stub shaft to be used with it [5; 6; 7; 8; 9; 10]. For all these reasons, it is interesting to eliminate the sensors. Recently, the operation without a mechanical speed sensor (sensorless) of induction motors has become one of the main attractions of interest for researchers and industrialists. They can be subdivided into two different families of strategies: the first is concerned with estimating the speed without using the machine model. These strategies have been articulated in the extraction and analysis of harmonics in the rotor slots and injecting a high frequency signal. The second method is based on observing the speed using the machine model. In this type, the design of observers is mainly articulated on the IM model and thus the observer is considered as a mirror to the machine model. In literature, many speed sensorless techniques have been proposed. The essential ones are the Extended Kalman filter [11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21], the adaptive reference model (MRAS) [22; 23; 24], the Luenberger observer [25; 26; 27; 28], the high gain observer [29], the sliding mode observer [30; 31; 32; 33], and the backstepping observer [34; 35; 36; 37]. The dominance of a particular method articulates mainly on the accuracy of speed estimation. For example, the model dependent estimation techniques are defined by its simplicity. However, the sensitivity to the system uncertainties is considered the dominant problem of these observers. The resistances of stator and rotor windings are playing a vital role during the estimation and for this reason; their values must be identified accurately to achieve precise speed estimation [38]. Indeed, estimation of speed without model requires an analysis of the spectrum to increase the speed control band. Therefore, the program becomes complex and requires more time for execution. The simplicity and effectiveness of the observers based on the model becomes an open subject for several researchers.