A fault-adaptive and observer-based sensorless strategy for a fault-tolerant five-phase BLDC motor

This paper will present the development process of a multiphase observer-based sensorless strategy possessing also reconfiguration capabilities with respect to the occurrence of some phase faults. The presented strategy is particularly suitable to be applied for the implementation of a cheap additional redundancy feature in order to augment the still existing fault-tolerant capabilities of some multiphase drives employed in safety-critical applications. The developmental steps will be described in detail after a preliminary motor modeling section, in particular the core stage of the multiphase sensorless scheme, more related with the rotor position and speed detection, will be illustrated at first and then, in a second step, the reconfiguration strategy linked with a certain subset of faults, that is opening of the phases, will be introduced subsequently; the proposed remedial policy will mainly involve the proper switching of the linear transformation used to get the equivalent two-phase description of the machine and of the employed back-EMF observer in turn. Simulation and preliminary experimental results will be shown at the end to validate the fault-adaptive properties of the proposed multiphase sensorless strategy; in this last case a proper Real-Time Simulation platform will be used.