Abstract : In the paper by Vaclavek et al. (IEEE Trans. Ind. Electron., vol. 60, no. 8, pp. 3047-3059, Aug. 2013), the local observability of both induction machine and permanent magnet synchronous machine under motion sensorless operation is studied. In this letter, the " slowly varying " speed assumption is discussed, and the permanent magnet synchronous machine observability condition at standstill is revisited.
