Improved dual-voltage freewheeling–based sensorless control strategy for switched reluctance motors

Abstract In this paper, a dual-voltage topology–based sensorless control strategy is proposed for switched reluctance motors (SRMs), aimed at enhancing torque performance by extending the turn-off angle under high-speed conditions and improving the applicability of pulse injection–based position estimation. Based on this structure, three operating modes are defined: reserved mode for the current-slope-difference method, fast demagnetization mode to improve current decay characteristics, and auxiliary mode to address issues caused by measurement errors. Each operating mode may include several sub-modes and is governed by dedicated switching logic. Subsequently, a characteristic-point update scheme that does not rely on motor parameters is proposed, along with a comprehensive error and fault analysis. The overall system requires no additional sensors or complex computation, making it suitable for cost-sensitive embedded applications. Simulation and hardware-in-the-loop results on a 6/4 SRM demonstrate improved pulse utilization, an extended conduction region, and reliable operation across a wide speed range, confirming the practical viability of the proposed approach for high-speed sensorless SRM drives.