Il bilancio integrato per le PMI

Accanto ai capitali finanziario e produttivo, ogni impresa fonda il proprio business e il proprio successo anche su risorse intangibili, quali il capitale intellettuale, il capitale umano, il capitale sociale e relazionale ed il capitale naturale. Il tradizionale bilancio economico-finanziario, però, non è adatto a valutare e rappresentare tali risorse, poiché è stato concepito con riferimento ad un’economia industriale fondata pressoché esclusivamente su capitali tangibili; pertanto, anche avuto riguardo alla realtà delle PMI, si rende oggi necessario introdurre nuovi strumenti e nuovi indicatori per la misurazione e la rendicontazione, che siano in grado di cogliere e valorizzare anche le componenti immateriali del capitale aziendale. In questo contesto, il bilancio integrato si pone come una forma evoluta di comunicazione aziendale, finalizzata ad illustrare come strategia, governance, modello di business, rapporti con gli stakeholder, performance passate e prospettive future, rischi e opportunità consentano anche ad un’impresa di piccole e medie dimensioni di creare valore nel breve, medio e lungo termine

Sensorless Capability of Fractional-Slot Surface-Mounted PM Motors

This paper investigates the capability of sensorless rotor position detection by means of injection of a high-frequency (HF) signal of fractional-slot surface-mounted permanent-magnet (PM) motors. In order to create an HF anisotropy, such motors are characterized by the presence of a ring around each pole. For the sake of completeness, different windings are considered: a distributed coil winding and a concentrated coil winding. The effect of eddy currents in the magnets, due to the HF signal, is also considered. The effect of the slot opening is also taken into consideration. Finally, the comparison with two different PM rotor topologies is addressed: an interior PM motor and an INSET motor

Analysis and experimental tests of the sensorless capability of a fractional-slot inset PM motor

The sensorless techniques based on high-frequency signal injection to determine the rotor position is applied to an inset permanent-magnet (PM) motor, whose rotor is characterized by small iron teeth between each couple of PMs. Although these rotor teeth, which are centered along the q-axis, do not significantly contribute to torque production, they yield appropriate rotor saliency to be exploited for the rotor position sensorless detection. The inset PM motor considered in this paper is characterized by a fractional-slot stator, i.e., by a fractional number of slots per pole and per phase. Such a solution is commonly used when a surface-mounted PM machine is considered since it exhibits a higher torque density. A 12-slot 8-pole inset PM motor is investigated as far as its self-sensing capability. Both finite-element analysis and experimental measurements are presented, showing satisfactory agreement. It is shown that the prototype of the inset PM motor available in the laboratory exhibits a good capability to be controlled by sensorless techniques. However, a negative effect is recognized by a nonnegligible ripple of torque and flux linkages. They affect the dynamic performance of the PM motor drive

Analysis and experimental tests of the sensorless capability of a fractional-slot inset PM motor

The sensorless techniques based on high frequency signal injection to determine the rotor position is applied to an inset permanent magnet (PM) motor, whose rotor is characterized by a thin iron tooth between each couple of permanent magnet. These rotor teeth yield the rotor to be anisotropic, so as its position can be detectable. The inset PM motor considered in this paper is characterized by a fractional-slot stator, that is, by a fractional number of slots per pole and per phase. Such a solution is commonly used when a surface-mounted PM machine is considered, since it exhibits a higher torque density. A 12-slot 10-pole inset PM motor is investigated as far as its self-sensing capability. Both finite element analysis and experimental measurements are presented, showing a satisfactory agreement. It is shown that the prototype of inset PM motor available in laboratory exhibits a good capability to be controlled by sensorless techniques. However, a negative effect is recognized by a non-negligible ripple of torque and flux linkages. They impact on the dynamic performance of the PM motor drive

Sensorless capability of fractional-slot surface-mounted PM motors

This paper compares two motors as regard their behaviour during sensorless rotor position detection by means of injection of a high frequency signal. The motors are characterized by the presence of a ring around each pole and by different windings: a distributed coil winding and a concentrated coil winding. The effect of eddy currents in the magnets, due to the high frequency signal, is also considered. The effect of the slot opening is also taken in consideration. Finally, the comparison with two different PM rotor topologies, an interior PM motor and a INSET motor, is addressed

Ring Losses Evaluation in Ringed-Pole PM Motors

In this paper, the ringed-pole surface-mounted permanent-magnet machine is investigated from the point of view of the ring losses. The rings around the poles create a high-frequency anisotropy that is useful to detect the rotor position by means of a high-frequency signal injection. However, the presence of the rings causes additional rotor losses. The causes of ring losses are investigated in the paper. The first cause is the high-frequency signal injection itself. The harmonics in the airgap magnetomotive force, which are not synchronous with the rotor and hence induce currents in the rings, are the second source of losses. The third source is the airgap flux fluctuation due to stator slotting. Machines of different sizes and winding types are investigated. A finite-element analysis and an analytical model are used to estimate the ring losses, comparing the results. The influence of the ring cross-sectional area on the ring losses is analyzed, showing that the ring losses can be reduced in certain configurations

Zero-speed sensorless drive capability of fractional-slot inset PM machine

This paper investigates the capability of an inset PM motor with concentrated coils fractional-slot winding to be controlled by means of sensorless techniques using high frequency signal injection. The inset PM motor considered is a 12-slot 10-pole motor, whose performance has been obtained by means of both finite elements simulations and experimental measurements. It will be shown that the motor presents good performance to be controlled by sensorless techniques, and the expected performance agree with the experimental results

Ring losses evaluation in ringed pole PM motors

In this paper, the ringed pole surface-mounted permanent magnet machine is investigated from the point of view of the ring losses. The rings around the poles are interested by the high frequency signal injection, that is useful to detect the rotor position. Such signal injection causes losses in the ring itself. Further, the rings are interested by other changing fluxes that can induce losses. This paper investigates the effect of other two sources of losses in the rings, in addition to the losses due to the signal injection. The first is constituted by the harmonics in the airgap magnetomotive force, which are not synchronous with the rotor and so they induce currents and losses in the rings. The second is the effect of the airgap flux fluctuation, due to the stator slotting. An investigation on both small size and large size machine is addressed. An analytical model is also proposed for evaluate the ringed pole feasibility