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Soressi E.,Ansaldo Sistemi Industriali
PEDES 2012 - IEEE International Conference on Power Electronics, Drives and Energy Systems | Year: 2012

DC motors have been used in the past as the workhorse of industrial systems until the introduction of the AC induction motors, about twenty years ago. Since then, the DC motors in the industrial plants have been replaced with more robust, less complex AC ones and the speed control was achieved by digital system controlled PWM inverters. But there was a time when the power electronics, digital control or even the analogical control was far to be introduced and the speed regulation, if even possible, was deputed to electromechanical devices. These equipments have been designed and manufactured in such a robust way that some of them are still working and used for the production, i.e. in metal industries. A particular configuration, the compound DC motor was widely used, for example for lifting and traction. The aim of this paper is to present how an actual supply chain for old DC compound motors can be upgraded with static DC converter achieving less losses and better speed response without the modification of the mechanical assembly. The paper begins with the description of the existing supply configuration, hence describe an analytical method to identify the motor parameters and behaviour and than presents the new supply configuration and an original calculation of the motor voltage suitable to achieve the required speed in a wide range of torque load without the need of a speed sensor. © 2012 IEEE.

Tessarolo A.,University of Trieste | Giulivo D.,Ansaldo Sistemi Industriali
SPEEDAM 2010 - International Symposium on Power Electronics, Electrical Drives, Automation and Motion | Year: 2010

Multi-phase machines are of increasing importance in today's electric drives and generation systems. While in three-phase machines stator leakage flux phenomena are usually described with a single parameter, a higher number of independent leakage inductances is required as the number of phases increases. The impact of leakage inductances on multi-phase machine performance, especially in PWM inverter-supplied motors, is proved by many studies. Hence the need originates for the electromagnetic designer to have easy-to-use but sufficiently accurate calculation formulas giving the complete set of mutual inductance in a multi-phase machine. This paper aims at providing such formulas making abstraction of the particular phase arrangement in the stator winding and under the hypothesis of equal phase belts. The computation algorithms provided are assessed against measurements on actual machines wherever possible; otherwise accurate Finite Element (FE) analyses are used for validation. © 2010 IEEE.

Tessarolo A.,University of Trieste | Castellan S.,University of Trieste | Menis R.,University of Trieste | Ferrari G.,Ansaldo Sistemi Industriali
IEEE Transactions on Industrial Electronics | Year: 2010

Split-phase synchronous motors equipped with multiple-stator three-phase windings, each supplied by a loadcommutated inverter, play an important role in today's very high power electrical-drive applications. A criticality of these systems is the possibility that commutations occur in different motor windings simultaneously. The resulting electromagnetic transient depends on the magnetic coupling of motor phases among them and with rotor circuits. In this paper, a model to describe this phenomenon is presented along with some dedicated tests, conducted on various split-phase configurations, to assess the model validity. Copyright © 2010 IEEE.

Soressi E.,Ansaldo Sistemi Industriali
IEEE International Conference on Automation Science and Engineering | Year: 2011

Safety in industrial plants is one of the main topics of the decade and this is reflected in the related rules proliferation. The well known safety rule EN954-1 [2] is going to be retired in December 2011. Two different rules have been introduced, the ISO EN 13849 [3] and IEC EN 62061 [5]. The two rules are not so easy to read and to apply because they introduce some statistical parameters that are not usual for system designers. The aim of this paper is to introduce an example of application of the IEC EN62061 and to identify if the same safety approaches that came from the application of the old EN 954-1 rule are still valid. © 2011 IEEE.

Tessarolo A.,University of Trieste | Bassi C.,Ansaldo Sistemi Industriali
IEEE Transactions on Energy Conversion | Year: 2010

Electric motors equipped with multiple three-phase windings are often used for the advantages they offer in terms of reliability, performance, and inverter power segmentation. When the windings are fed by independent voltage-source inverters (VSIs), circulation harmonic currents can occur in stator phases. If the motor is an induction machine, circulation currents are known to originate form transient imbalances in the applied voltages due to inverter switching. This paper investigates the problem when a synchronous machine is used and shows how additional (and possibly major) sources for circulation currents can arise in this case (even with a round-rotor design) due to the nonsinusoidal air-gap flux distribution. The phenomenon is illustrated for a 45-MW quadruple three-phase synchronous motor supplied by four medium-voltage (MV) multilevel VSIs. Its circulation currents are predicted with two alternative methods, i.e., analytically and from time-stepping finite-element simulation. The results obtained in both ways are shown to well match measurement results collected on the actual motor during full-load system testing. © 2006 IEEE.

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