Nonzero Freewheeling Current-Based Sensorless Control of DTP-PMSM Under Single-Phase Open-Circuit Fault

This article investigates sensorless rotor position estimation for dual three-phase permanent magnet synchronous motors (DTP-PMSMs) under single-phase open-circuit fault conditions, focusing on the effects of mutual inductance between spatially shifted windings. A novel analytical expression for the nonzero freewheeling current is derived, clearly demonstrating that it contains rotor position information and can be directly utilized for position estimation. To enhance reliability, a middle-point current sampling strategy is proposed to accurately capture the nonzero freewheeling current during fault conditions. The sampled current is then processed using a SOGI-PLL-based rotor position estimation method. Experimental results confirm the effectiveness and robustness of the proposed sensorless control approach.