This paper proposes a standstill method for identification of the magnetic model of synchronous reluctance motors (SyRMs). The saturation and cross-saturation effects are properly taken into account. The motor is fed by an inverter with a short sequence of bipolar voltage pulses that are first applied on the rotor d-and q-axes separately and then simultaneously on both the axes. The stator flux linkages are computed by integrating the induced voltages. Using the current and flux samples, the parameters of an algebraic magnetic model are estimated by means of linear least squares. The proposed method is robust against errors in the stator resistance and inverter voltage, due to the high test voltages (of the order of the rated voltage). The fitted model matches very well with the reference saturation characteristics, measured using a constant-speed method, and enables extrapolation outside the sample range. The method was tested with a 2.2-kW SyRM, whose shaft was uncoupled from any mechanical load, which is the most demanding condition for this method. The proposed method can be used for automatic self-commissioning of sensorless SyRM drives at standstill.

This paper proposes a sensorless control scheme for synchronous reluctance (SyR) motor drives based on the direct-flux vector control (DFVC) method. The control operates in stator-fluxoriented coordinates, using constant switching frequency. A hybrid position and speed observer is proposed, based on the combination of the active flux concept and high-frequency signal injection and demodulation. The two methods are fused together to form a unique position and speed estimate signals, with seamless transition between the two models based on reference speed. The proposed observer covers a wide speed range, from standstill operation at full load to flux weakening (FW). Furthermore, it is inherently immune from position estimation error caused by cross saturation, as proven mathematically and experimentally. The motor is operated according to the maximum torque per ampere (MTPA) law. Specific issues related to MTPA around zero torque are addressed in this paper. The proposed control technique extends the range of application of the DFVC to encoderless drives, and can be usefully adopted in those applications where both zero-speed and FW speed range operations are necessary, such as home appliances, or automotive and aerospace actuators and generators. A 2.2-kW SyR motor prototype was tested to verify the feasibility of the proposed method. Key tuning aspects are addressed in this paper.

Purpose -The purpose of the paper is to provide an initial study on the Italian mobile payment services market, and to identify and assess the main diffusion drivers of mobile payment applications.Design/methodology/approach -The research design integrates an exhaustive census of all Italian mPayment applications and an in-depth analysis of the most significant cases performed through the case studies methodology: ten user companies or ''merchants'' and six service providers were analyzed through semi-structured interviews given to top managers.Findings -Through the census, 21 mPayment applications and related services were identified. In addition to this, the case studies brought greater understanding of the key diffusion drivers: strong inhibitory factors and adoption barriers are still restricting user adoption despite the many benefits related to these services.Research limitations/implications -The research represents a first, exploratory study of a market at its embryonic stage of development. Nevertheless, given the global magnitude of the Italian mobile telecommunications market and the gradual rise of the mPayment paradigm, the analysis can provide a valuable basis for future studies in the field.Practical implications -The findings can support a wide set of stakeholders -both first movers and newcomers of the mobile payment segment -in their offer definition and market making choices.Originality/value -The paper combines a census and a case study methodology to delineate the offer's state of the art for innovative, mobile channel-based payment services; moreover, its assessment of the applications' core benefits, diffusion drivers and adoption barriers can be tested for generalization to different contexts.

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In high-performance control of ac machines through variable frequency drives, the knowledge of machine parameters plays a decisive role. The accuracy with which machine parameters can be known is directly related to the time and effort put in testing and commissioning process. In the ever-demanding industrial environments, the time spent on parameter identification translates into loss of production. To reduce commissioning times, research in this direction has focused on automatizing the identification procedure without loss of accuracy. This paper reviews different lines of research adopted over the past few decades for machine parameter identification. Parameter estimation of ac machines is considered because of their widespread applications from servomechanisms to traction to aviation. The surveyed works include self-commissioning schemes that have become an integral part and salient feature of modern electric drives. This feature enables the drives to automatically identify machine parameters and tune the control loops.