Load invariant sensorless control of a SRM drive using high frequency signal injection

This work presents a load invariant position estimation technique for switched reluctance machine (SRM) drives based on high frequency signal injection methods. A high frequency rotating voltage vector is superimposed on the main excitation. The spatial saliency information is extracted using synchronous reference frame filtering. A robust position estimate is achieved by using an observer to track the spatial saliency. The theoretical spatial saliencies for a three-phase SRM can be derived using the doubly salient model of the machine. The proposed method is capable of providing continuous dynamic position estimation from zero to mid-range speeds with negligible load dependency.