The convergence and the estimation error of a high frequency voltage injection sensorless control depends strictly on the synchronous machine adopted and on the working point where it operates. In order to estimate the self-sensing capability range of the motor, it is necessary to know its parameters accurately. The aim of this paper is to show a new solution to identify the convergence range through a differential parameter approximation with less experimental and computational burden. The method is validated through finite element analysis and experimental measurements for two different types of synchronous motors.

This paper describes the design and realization of a Synchronous Reluctance (SynRel) motor with the maximum feasible magnetic saliency, both from a practical and industrial point of view. The performance of the SynRel motor is strictly related to the magnetic saliency which is limited by the iron saturation and influenced by the rotor flux barrier configuration. In the paper, the maximum achievable value for the magnetic saliency is first investigated. Then a specific rotor design which allows to obtain a saliency value as close as possible to the theoretical one is introduced. This design is achievable thanks to the adoption of Additive Manufacturing technology. In this way maximum flexibility in the rotor design can be exploited to maximize the motor performance increasing the magnetic saliency.

The paper deals with the online incremental inductances estimation of a synchronous motor at low speeds using a high-frequency voltage injection. The control scheme is analogous to that used in position estimation algorithms, with the difference that the current control and the rotating voltage injection operate on the real dq axes. Thus a position sensor is required to apply this method. The corresponding current response is measured, filtered, and processed with an ellipse fitting technique. The estimated ellipse coefficients are then used to retrieve the incremental inductances online without the need of any post processing. A novel formulation to express the estimation error valid for other conventional signal injection techniques is presented. The method has been validated experimentally on a reluctance synchronous motor at locked rotor and during load and speed transients.

Sensorless control schemes are object of great interest in the synchronous motor drives field. They permit to avoid the use of position sensors in the system, allowing several benefits. In this paper a sensorless control scheme is proposed for low speed or standstill operation of a synchronous motor drive, characterized by a rotor anisotropy. The method is based on a high frequency voltage injection in the stator motor windings. High frequency current response to this injection is obtained from the measured currents thanks to a high pass filter. These filtered currents describe an ellipse trajectory, that is deeply analysed considering all its components. In particular, ellipse major semi-axis tilt is related to the rotor position. A recursive least squares estimator is proposed for the ellipse equation coefficients identification. After some manipulations, the rotor position is extrapolated from these information.

In this paper the sensorless control of a permanent magnet synchronous motors operating at super-high speed (125000 rpm) is investigated. The considered application is a compressor for the air supplying in a fuel cell cathode of an electrical car. Due to the super-high speed, a sensorless control algorithm, based on the extended Kalman filter (EKF), has been adopted. A particular implementation of EKF has also been tested: the EKF equations were implemented using normalized motor parameters, so that the choice of EKF parameters is straightforward considering different motor parameters. The system has been designed and implemented considering three different machines. Experimental test on three machines are included in the paper and compared with simulation results.

The variation of the self-sensing capability of different type of electrical machines due to parasitic effects is considered in this papers. Thanks to a specific simulation strategy the variations of the machine saliency and the error angle are computed considering different rotor positions and different working points. It is shown that a large variation occurs in particular working points. The presented approach is useful during the design process of the machine in order to assess the self-sensing capability of the machine and its impact on the control scheme adopted in the drive.

An analysis of the magnetic behavior of different slot geometries is proposed by means of finite element (FE) software. An intentionally created anisotropy is introduced in the rotor bar geometry, so as to allows a sensorless detection of the IM rotor position. The proposed FE procedure allows to evaluate the sensorless control capability of the IM. The parameters of the induction motor (IM) are determined by means of a FE procedure, based on the d- and q- axis model of the machine. Such a procedure is quite rapid, since is based on the time harmonic response to a high frequency injected signal in the stator winding. This procedure is used to predict the variation of the IM parameters and it results to be useful for both analysis of the IM performance and the design step of the machine. A rotor geometry with an intentionally created magnetic saliency have been analyzed. The rotor prototype is under construction, in order to verify the predicted results.