Identification of time-variant high frequency parameters for sensorless control of PMSM using an internal model principle based high frequency current control

Standstill and low speed self-sensing based field oriented control of PMSM using the high frequency signal injection method requires a sufficient saliency ratio of the high frequency differential inductances of the machine. Therefore these inductances need to be known precisely to be able to guarantee stability of the sensorless control. In order to perform the identification, the conventional field oriented control scheme is extended by additional PI-type controllers in a positive and negative sequence high frequency coordinate system, thus resulting in zero steady state control error in case of superimposed sinusoidal high frequency test current reference values. Moreover the extended control scheme provides a direct demodulation of sine and cosine parts of the high frequency control signals and therefore enables a direct identification of all model parameters relevant for HF injection based sensorless control (differential self- and mutual inductances and high frequency resistances). In contrast to conventional methods, no prerequisites for the parameters or its´ dependencies have to be fulfilled.