Signal-injection-aided position and speed estimation for PMSM drives with low-resolution position sensors

The aim of this paper is to reduce the low-speed limitation of PMSM drives that use low-resolution position sensors. It is recognized, for the first time, that this may be overcome by merging signal-injection-based self-sensing and low-resolution sensor technologies, if the machine possesses a detectable amount of electromagnetic saliency. The supplementary information coming from the injection of an additional high frequency magnetic field may be used to aid the low-resolution-based position and speed estimation algorithm, significantly improving the low-speed performance of the drive. In this research contribution, the quantization-harmonic decoupling vector-tracking observer is used for speed and position estimation. It is shown how this algorithm can be easily integrated with any high frequency signal injection method. Extensive experimental results are provided demonstrating the significant performance improvements at low speeds for a PMSM drive using 1, 2 and 3 bit-per-pole-pair sensing systems, when signal injection is used to aid position and speed estimation.