Post-Fault Voltage Limit of Dual Three-Phase Induction Machine Against Slip Frequency with Single and Two Isolated Neutrals

Over the last decade, the rapid growth in power electric components and embedded systems has accelerated the adoption of multiphase machines, especially with their capacity for power segmentation and the emergence of critical applications, requiring high level of fault tolerance. For their simple structured designs through rewinding of standard three-phase machines, dual three-phase drives (D3) have gained significant attention. Nevertheless, simulation results have concluded that dual three-phase machines under any fault condition only achieves half of the rated current either with single or two isolated neutrals. Thus, the objectives of this research are to provide a unified discussion on the post-fault voltage limit of induction machine against slip frequency, study the effect of DC-bus voltage limitations on the maximum achievable output torque under optimum current control with one-open phase fault and justify the lower group of line-to-line voltages can be higher than the upper group of line-to-line voltages. Also, vector space decomposition technique is used to convert the phase variables and is corresponded to the new variables via decoupling transformation. The result from the study can be beneficial to the industries that commonly using multiphase induction machines for operations.