Using Volt-sec. sensing to extend the low speed range and the disturbance rejection capability of back-EMF-based self-sensing

This paper introduces usage of Volt-sec. sensing in back-EMF-based self-sensing (sensorless) induction machine drives. In practice, both inverter nonlinearity and dc bus voltage affect back-EMF estimation accuracy, and therefore self-sensing performance. A real-time Volt-sec. sensing scheme to measure the terminal Volt-sec. vector for each switching period is introduced in the paper. The measured Volt-sec. information can be used in the back-EMF state filter such that the effects from inverter nonlinearity and dc bus voltage measurement errors are mitigated. The resulting extended low speed range and enhanced disturbance rejection capability are quantified via experimental evaluation.