Maurizio Mazzucchelli

PWM Systems in Power Converters: An Extension of the ``Subharmonic'' Method

In this paper the extension of the subharmonic method for pulse-width modulation (PWM) systems, in the case in which the ratio between modulating and carrier wave amplitudes can be varied from 0 to ¿, is studied in an analytical way. This method allows us to obtain an inverter output waveform variable continuously from a nearly sinusoidal to a square wave and to increase somewhat the amplitude of the fundamental output wave without a significant worsening of the harmonic content, a feature particularly useful for drives with wide speed variations or which need an optimized use of dc power supply.

Development of open-loop and closed-loop techniques for the optimization of modular multilevel conversion structures

New control and modulation techniques are proposed for the reduction of the DC-link capacitors in cascade multilevel converter structures for medium-voltage AC motor drives. Two different approaches have been followed, the first one based on the synthesis of suitable modulating signals, and the second one based on the feedback of the motor currents and of the DC-link voltage in each H-bridge module. A new DC-link passive filtering approach is also proposed, which has been studied and optimized with reference to such techniques. The explanation of the proposed techniques and the most significant analyses and results are reported

Integrated Freight Terminal Simulation Tool: Design and Implementation

Multimodal transport is an attractive research field, and this interest is probably due to the growth of the demand for transport of freight. In this paper, the problem of modelling the Displacement and Stocking Service (DSS) module of a freight terminal has been dealt with. The model proposed in this work is divided into two main sets of processes; each process is suitable to be modelled using state automata, and their behaviour is event driven. Events are scheduled according to the information coming from other terminal modules; these modules are neglected in this paper, as they are considered in terms of the relationships with the DSS.

Dynamic Performances of AC Drives Fed from Power Transistor-Thyristor Inverters

A simulation procedure has been pointed out for investigating problems concerning road traction drives based on three-phase induction machines supplied by modulated inverters. The inverter employed is not conventional because it utilizes both thyristors and power transistors. The solution proposed allows weight and size to be minimized with respect to a conventional thyristor drive. As a consequence, the design presented meets, in a satisfactory way, the requirements of a drive that is to be used in an electric vehicle, In the simulation, the inverter is represented as an independent voltage generator which produces various voltage waveforms at the ac terminals. The induction machine is described according to a dynamic model based on Parks two-axis theory. A computer program has been used for simulation of the drive dynamics, and some quantitative results have been obtained with reference to an actual traction drive.

The displacement and stocking service module of integrated freight terminals: design and implementation of a discrete-event simulation tool

In this paper, the authors introduce the simulative approach as an aid for the management of integrated freight terminals. In order to detail the scope of this work, the definitions of integrated freight transport network and terminals is given in the full paper. The simulation tool presented in this work is based on a discrete-event model. The model has been implemented using the object-oriented programming technique, achieving a discrete-event simulation tool. Such a simulation tool is not site oriented, that is to say that it is suitable for application on different terminal (or sites). The simulator has been validated and then applied to an existing freight terminal. In this paper, the authors present the main issues of the work, including the results related to the application of the simulation tool to the case study.