Investigation of key factors influencing the response of permanent magnet synchronous machines to three-phase symmetrical short-circuit faults

This paper investigates the three-phase symmetrical short-circuit characteristics of a permanent magnet synchronous machine (PMSM). Closed-form solutions are derived to predict both the steady-state and transient response of a PMSM to three-phase symmetrical short-circuit (SSC) faults. The developed expressions account for the impact of pre-fault operating conditions and include provisions for incorporating magnetic saturation effects. The influence of machine parameters is studied to identify the key parameters that have a major influence on the steady-state and peak transient values of the fault currents. It is shown that increased inductance saliency ratio, reduced stator resistance, and higher magnetic saturation all increase the peak transient value of the demagnetizing d-axis current. Finite-element (FE) analysis is used to build confidence in the fault current predictions of the developed analytical model.