F. Tissi

Surface field measurements in vector characterization of Si-Fe magnetic steel samples

In this work we discuss some procedures to increase the accuracy in the measurement of the magnetic field strength using Round Rotational Single Sheet Tester RRSST frames. The procedures are discussed jointly with the use of different magnetic field probes, such as flat coils and Hall sensors, and with a suitable shielding geometry. Experimental comparison between different methods and a discussion about the results is presented.

Prediction and Control of Transformer Inrush Currents

In this paper, we propose a dynamic model of the electrical transformer suitable for the numerical prediction of the inrush currents due to the arbitrary initial excitation of a transformer after a switch-OFF. In particular, the proposed model can be helpful to control strategies to avoid a transient current overshoot, based on the prediction of the residual magnetic flux.

Time domain deconvolution approach relying on Galois sequences

Purpose – The paper seeks to present a novel pulsed eddy currents (PEC) non‐destructive technique to investigate deep cracks in metallic structures.Design/methodology/approach – The method is based on the time‐domain analysis of the “defect response” and joins the PEC approach with the exploitation of the peculiar auto‐correlation properties of the Galois sequences. The procedure, relying on the deconvolution of Galois sequences, greatly improves the signal to noise ratio (SNR) and thus the operating depth. De‐convolving even short Galois sequences allows one to investigate at depth ranges larger than those allowed by the conventional pulsed excitation techniques.Findings – The technique has been tested on a benchmark and compared with numerical simulations. The experimental results showed that the SNR and the detection depth range have been significantly improved.Research limitations/implications – Some limitations of the measuring set up were evidenced requiring a new measuring apparatus if explorations...

Contact-Less Speed Probe Based on Eddy Currents

In this work, we present a technique for the speed measurement of a metallic body with flat surface and without marks, using a contact-less probe. Basically, the measurement system is made with a permanent magnet for the magnetic field generation and a Hall plate as pick-up sensor. The contact-less probe geometry, the electronic circuit and the devices used for the output signal treatment, including a suitable signal processing applied to increase the signal noise ratio are described. In addition, a theoretical analysis of the probe sensitivity is proposed. In order to show the practical performance of the speed measurement proposed, a series of experimental tests is presented.

Performances prediction of inductive blocking devices for the mitigation of the lightning indirect effects

In this paper we propose a computational procedure to evaluate the performances of inductive blocking devices used for the mitigation of indirect lightning effects on electrical and electronic equipment in the avionic environment. The non linear behavior of the blocking devices are simulated using a finite difference scheme in time domain. Computations and experimental results are compared and discussed.

Modeling of inductive blocking devices for the mitigation of indirect lightning effects

In this paper we propose a computational procedure to evaluate the performances of inductive blocking devices used for the mitigation of indirect lightning effects on electrical and electronic equipment, with special relation to the avionic environment. The non linear behavior of the blocking devices is simulated using a FEM scheme in time domain. Computations and experimental results are compared and discussed.

Permanent magnet synchronous generator coupled to variable speed small wind turbine: Modeling and experimental testing

This paper deals with a typical mini aero-generator system connected to a low voltage power network. Each component of the system is modeled by a suitable equivalent circuit. The permanent magnet synchronous machine is replaced by its two axis equivalent model. The total network can be numerically analyzed by a numerical solver and the performances of the power generation system at variable wind speed and mechanical torque can be predicted. The accuracy of the modeling is proved by experimental tests made with a dedicated testing chain designed and realized in our laboratory.

Efficiency modeling of motor drives for electric vehicles

The paper deals with the modeling of motor drives for electric vehicles, in order to estimate their efficiency. For the experimental validation of the model, a reduced scale version of the system has been realized in our laboratory. Simulation results are compared with measured.

Electromagnetic scattering applied to the non destructive evaluation of mortar and grout injections

A new system for the diagnosis of the grout injections is proposed in this paper. The system allows to find the effective and homogenous diffusion of the grout injected in masonries and other similar structures, interested by renovation and consolidation actions. The basic working principle is based on the detection of the modification of the electromagnetic characteristics at different depth inside the masonry, mainly due to the presence of grout injection. The set-up and the calibration of the detection system have been performed by means of a dedicated theory and laboratory tests, using brick walls and other special grout elements, also mixed with metallic powders, in order to enhance the detection sensibility. On-site experimental tests have been carried out on ancient stone masonry walls, and the recorded data, suitably processed by dedicated inversion digital codes, have been verified by inspection, in order to highlight the effectiveness and the reliability of the proposed system.