Modeling, analysis and performance of variable speed nine-phase electric drives

Multiphase machines are of increased interest due to their potential advantages of increased reliability, greater fault tolerance, harmonic current reduction and extended speed torque capability. A better understanding of the utilization of higher order harmonics, modes of operation and torque capability in different modes are necessary to realize these possible advantages of higher phase order machines. Due to the high number of coupled variables, the proper modeling and analysis of the higher phase order machine turns out to be a challenging task.;In this thesis, a distinctive approach is proposed for the better torque improvement of Nine Phase Interior Permanent Magnet (IPM) Machine by the utilization of higher order harmonics which contribute positively to the resultant torque. An approximate Fourier series model and full order q-d model based on winding function theory is proposed for the generalization of the dynamic model of the Nine phase IPM Machine with and without the inclusion of damper rotor bars. Analytical Finite Element Simulation is also performed for the accurate prediction of the air gap flux characteristics of the 9-phase IPM Machine under the rated operating conditions. Similarly, for the verification of the model, the full order model is simulated and induced EMF on phase winding is compared with the Experimental observations. This approach of Fourier approximation and q-d full order modeling is also extended to three machine configuration of Nine Phase IPM Machine and Nine phase Induction Machine to observe the significance of torque contribution from each machine sets which aids for the realization of better fault tolerance and increased reliability of the system.;For the extended speed/torque operation of Nine phase Induction Machine, the concept of Pole Phase Modulation is introduced to operate Nine phase Induction Machine as Nine phase, 4 pole or 3 phase, 12 pole configurations. With the new design method based on basic principle of turn and winding functions, both operation of the machine is examined at rated condition with the realization in Finite Elements. For the precise estimation of the parameters, different estimation methods are applied in both configurations and a comparative analysis is presented. The full order simulation is performed using MATLAB/Simulink and with the help of Finite Elements, vector control is realized to verify the extended speed/torque operation for pole phase modulated Induction Machine.