Influence of PMSM Parameters on the Active Open- vs Short-Circuit Fault-Reaction Strategy

Defining the Fault-Reaction Strategy (FRS) is crucial for Permanent Magnet Synchronous Machines (PMSMs). In general, two approaches can be adopted: Active Open-Circuit (AOC) and Active Short-Circuit (ASC), with pros and cons. The former is safer for the motor, as high demagnetizing current are avoided, but can lead to undesired and dangerous voltages. The latter limit voltages effectively, but induces high currents that can irreversibly demagnetize the motor and stress the converter components. This paper proposes a unified framework to compare AOC and ASC by linking them to key PMSM parameters (anisotropy and PM flux linkage), through both Constant Parameter Model (CPM) and Finite Element Analysis (FEA). Furthermore, a mixed AOC+ASC strategy is proposed to simultaneously mitigate currents and avoid overvoltages. The scheme is related to the PMSM parameters and it is validated on four machines, with different saliency ratios and PM strengths, highlighting the impact of saturation and temperature on the final FRS decision.