Multi-phase motors have attracted increasing attention in fields seeking high reliability, such as electric vehicles, ships, and rail transit, as they exhibit advantages, such as high reliability and fault tolerance. In this study, we consider a 12-phase permanent magnet synchronous motor (PMSM). First, a mathematical model of the 12-phase PMSM in the static coordinate system is established and the model is simplified according to the constraint condition of neutral point isolation. Second, according to the principle of invariant magnetomotive force under normal and fault conditions, two optimal control strategies of winding current, i.e. maximum torque output (MTO) and minimum copper consumption (MCC), are proposed. For a single-phase open-circuit fault, two optimization methods are used to reconstruct the residual phase current, such that the motor can maintain normal torque output and exhibit lower torque ripple under the fault state. Finally, system simulation and experimental research are conducted; the results verify the accuracy and feasibility of the fault-tolerant control strategy of the 12-phase PMSM proposed in this paper.
Research on torque ripple under healthy and open-circuit fault-tolerant conditions in a PM multiphase machine
