Subspace-State-Based Short-Circuit Current Observer for Interturn Short-Circuit Faults in Symmetrical Six-Phase PMSMs

Interturn short-circuit fault (ISCF) is a serious fault type in machine system. This paper proposes a novel Luenberger state observer (LSD) of short-circuit current using the xy subspace states for symmetrical six-phase permanent magnet synchronous machines (PMSMs). For six-phase control systems, the current symptoms in each subspace are affected by the ISCF. Compared to the dq subspace voltage equations, the xy subspace voltage equations are simpler. To reduce the complexity of the observer matrices, the short-circuit current observer is developed by the xy subspace states. Experimental results show the effectiveness of the proposed observer for different fault severities and operating conditions.