Extending low speed self-sensing via flux tracking with volt-second sensing

This paper introduces an enhanced speed self-sensing method that tracks stator flux linkage in electric machines at very low speeds. Volt-second sensing technology is used to mitigate the inverter nonlinearity, which is the major source of flux estimation error in the very low speed range. By integrating volt-second sensing in the Gopinath style closed-loop flux observer, the rotor speed information with more precision and lower noise is extracted from the estimated stator flux. Experimental results show that the proposed self-sensing method extends the low speed operating range, reduces the speed and torque ripple, and increases the disturbance rejection capability compared with the traditional self-sensing method based on back-EMF tracking. This research is sponsored by Toshiba Mitsubishi - Electric Industrial Systems Corporation (TMEIC), Fuchu, Japan.