Sensorless control of interior permanent-magnet synchronous motors based on a fictitious permanent-magnet flux model

A reduced-order position observer with stator-resistance adaptation for PMSM drives

“…Since the back electromotive force (EMF) is proportional to the rotational speed of the motor, parameter errors have a relatively high effect on the accuracy of the estimated back EMF at low speeds [4]. Improper observer gain selections may cause unstable operation of the drive even if the parameters are accurately known [3], [5].…”

Position estimation for synchronous motor drives: Unified framework for design and analysis

“…The observers proposed in [9], [10] are similar to [1], [2], but since an additional integral action is used in their state observer structures, their order is higher and they have more design parameters to be tuned. The observer structure used in [5] is similar to [3], [4], except that the PM-flux magnitude is also estimated, which also increases the order of the observer.…”

“…For salient machines, the estimation-error dynamics have been rigorously analyzed only in a few papers [3]- [5], [8], [12]. A concept of the fictitious flux has been used in order to turn the salient machine model into a more favourable nonsalient form [5].…”

Analysis of an Adaptive Observer for Sensorless Control of Interior Permanent Magnet Synchronous Motors

“…It is typical of interior magnet motors that the rotor saliency complicates the application and analysis of fundamental-excitation methods [2], [5], [7]- [10], contrary to signal injection methods. The stability of the drive system is the most crucial design criterion [6], [8]. In this paper, an observer gain providing a stable and well damped system is proposed based on the linearized model of the system.…”

“…An error term is calculated from the measured and estimated quantities, and the rotor speed is usually adjusted by a PI mechanism. The current or the stator flux has been used as a state variable of the observer [3]- [8]. An observer design using the stator flux error as a state variable has also been proposed [9].…”