Enhanced Sensorless Control of Switched Reluctance Motors Using Inertial Phase-Locked Loop for Extended Speed Range

Sensorless control of switched reluctance motors (SRMs) often requires a hybrid mode combining low-speed pulse injection methods and high-speed model-based estimation. However, pulse injection causes unwanted audible noises and torque ripples. This article proposes an enhanced model-based sensorless approach to extend downwards the speed range in which sensorless control can work without injection. An inertial phase-locked loop (IPLL) based on a stator flux observer is introduced for position estimation. Compared to the conventional phase-locked loop scheme, the IPLL offers a more robust disturbance rejection capability and thus reduces the flux model errors at lower speeds. Experimental results substantiate the feasibility of the extended low-speed operation using the model-based sensorless control approach.