A new control of a synchronous motor without position and speed sensors: the current-model

Synchronous motors require position and speed sensors to dynamically control them. This paper presents new solutions of speed and position estimators, to be included in a sensorless control scheme. The difference between the components of the measured and estimated stator current vectors are used as inputs of a controller whose output is the estimated speed and, by integration, the estimated position. The vectors are projected on the estimated rotor frame. Two solutions are studied using either the D-axis electrical equation (ID-Model) or both d, q equations (IDQ-Model) to estimate the current vector. Their performances are discussed and compared with the performances obtained with a resolver. The case of standstill and low speeds is considered