Comparative Study Of Back EMF Based Sensorless Control Methods For Dual Three-Phase PMSM

Multiphase electrical machines have gained increased attentions recently due to its fault tolerance capability which is of great importance for more-electric aircraft application. This paper studies sensorless control of a high-speed dual three-phase electrical machine for turboprop aircraft green taxiing motor and engine generator applications. After introduction of a detailed mathematical model of a dual three-phase permanent magnet machine, two different types of back EMF based sensorless control are compared in this paper. The first method uses a phase-locked-loop (PLL) type speed and rotor position estimator and the other uses a Luenberger observer estimator. The effectiveness of these two different methods is demonstrated using simulations in the Matlab/Simulink environment. The comparison studies show that Luenberger type estimator has better dynamic performance but suffers high frequency noise in the estimated speed error and requires the use of machinal parameters. In contrast, PLL type estimator has inferior but acceptable performance. Its low-pass characteristics frees it from the high frequency noise. Moreover, it does not require the use of mechanical parameters.