Abstract
This paper presents new analyses of convergence characteristics of the D-state-observer using speed estimate with huge error for sensorless drive of permanent-magnet synchronous motors, and demonstrates high convergence performance of the D-state-observer through experiments. It is analytically shown that the maximum error of steady-state phase estimate by the D-state-observer can remain within ±π/4(rad) even if the speed estimate with huge constant error is used in the observer. The experiments demonstrate that the D-state-observer accompanied with the generalized integral-type PLL method can estimate correctly actual phase and speed of the rotor in all sensorless operation range even if the estimations start with huge initial errors.
