الفهرس 
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Abstract
Multiphase induction machines have a significant advantage over three phase ones, including lower torque pulsations with higher frequency, less DC-link current harmonics, lower power per phase, and higher fault tolerant capability. Therefore, multiphase machines were more favored in ship propulsion, traction and electric vehicles. Multiphase induction machine modelling represents a crucial research topic for both machine control and performance evaluation purposes. Generally, multiphase induction machines are preferably modelled using the vector space decomposition technique with some assumptions to simplify the mathematical model. However, different sources of non-linearities, including low order harmonics mapped to secondary subspaces, cross-coupling saturation and iron losses result in a notable deviation from the experimentally measured waveforms. Furthermore, considering full symmetry amongst motors phases seems to be a rather idealistic assumption. Fractional order modelling has recently emerged as a promising mathematical technique to model highly nonlinear electrical and mechanical systems. Fractional order models offer additional degrees of freedom by adding fractional differential operators. Recently many researches have focused on representing electrical and mechanical orders based on fractional calculus to give more accurate mathematical representations. Fractional order controllers have also been widely used due to its flexibility, robustness and inherently iso-damping properties. Fractional order PI controller is applied in Field Oriented Control to enhance controller robustness against gain variations and uncertainties. This work proposes an improved vector space decomposition (VSD)-based fractional order model of an asymmetrical six-phase induction machine under both healthy and open phase fault conditions with different neutral arrangements. The appropriate differentiation orders have been obtained by optimizing the error function between simulated and experimental waveforms. The results are compared with the conventional integral order-based model. Experimental validation has been carried out using a 1.5Hp prototype induction machine. In addition to that, this work also proposes a fractional order controller on an asymmetrical six phase induction machine. The study is carried out by frequency domain analysis showing the effect of using fractional order controllers on system robustness and stability.