Dynamics and control of a five phase induction machine

General and special case expressions for determining the real and reactive powers in a multiphase system have been derived. This has been simplified by the use of the stationary complex reference frame of transformation which transforms a set of m real variables into a set of (m-1) complex vectors (when m is odd). The mth vector is real and is referred to as the zero sequence. For a system with an even number of phases (m is even), the number of complex vectors is (m-2) and there are two zero sequence quantities. The complex vectors are conjugates of each other such that during the analysis only half of them (which are the positive sequence components) are sufficient to give the desired result. In this work, the expressions for determining the real and reactive power of the three, five and seven phase machines have been obtained.;A five phase induction machine has been modeled. The winding function method is used to calculate the self and mutual inductances in the stator windings and the rotor circuits, with constant air gap in which the space harmonics of the stator windings and rotor circuits are accounted for. A n x n complex variable reference frame transformation is carried out to simplify computation of the currents, voltages and torque equations. Computer simulation results of the no-load starting transient have been shown with the response of the machine for a change in the load torque. This approach has made it possible to calculate the rotor bar currents.;A five-phase carrier based PWM (Pulse Width Modulation) induction motor drive has been analyzed. The induction machine windings have been connected in alternate ways to increase the torque produced by the machine. A third harmonic voltage component has been injected to determine the ability of a five phase machine to contribute a third harmonic torque component to the fundamental torque component. It has been found out that with sinusoidally distributed stator winding, the effect of the third harmonic torque component is negligible.;The dynamics of a five-phase induction motor under open phase faults has been discussed. Using stationary reference frame and harmonic balance technique, circuit based models have been used to analyze the open phase, two adjacent phases and two non-adjacent phase faults. Simulation and steady state results have shown that the five phase machine can start and develop torque with one or two of its phases missing. Mall signal analysis has been carried out to determine the stability of the machine at different open phase fault conditions, revealing that despite the missing phases, the machine is stable at relatively high operating speed.;A voltage source inverter has been reconfigured for the purpose of obtaining high speeds in the regions of field weakening operation. The motive being to investigate the possibilities of operating a multiphase induction motor drive in field weakening region under optimum torque production. With a multiphase systems, different winding connections can be obtained apart from the conventional star and delta configurations. Such connections would give higher voltages across the machine's phase winding and thus allowing the for relatively higher torque production in the regions of field weakening operation.