A Comprehensive Voltage-Behind-Reactance Model of Twelve-Phase Synchronous Motors

The increased interest gained by the multiphase (MP) machines in recent years is justified by their potential advantages. With respect to three-phase machines, the multiphase ones have lower phase currents for a given power thus requiring reduced semiconductor switch ratings. Additionally, they show fault-tolerant behaviour thanks to the intrinsic redundant structure. Therefore, the drive reliability can be greatly enhanced since the machine can continue to operate even if one or several phases are lost. The definition of circuital-based machine models enables the simulation of single phase or multiphase faults. This feature is essential for the development of control strategies exploiting MP fault-tolerant capabilities through the additional degrees of freedom. This paper proposes a machine model based on the voltage-behind-reactance (VBR) modelling approach that properly accounts for the multiple mutual couplings between the machine phases. Simulation results are provided for a quadruple three-phase synchronous motor.