Simone Castellan

On the Modeling of Commutation Transients in Split-Phase Synchronous Motors Supplied by Multiple Load-Commutated Inverters

Split-phase synchronous motors equipped with multiple-stator three-phase windings, each supplied by a load-commutated inverter, play an important role in todays 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.

Modeling and Simulation of Electric Propulsion Systems for All-Electric Cruise Liners

Electric propulsion for cruise liners has now become a standard owing to its several advantages. However propulsion drives have a large impact on the ship power system. This gives rise to the requirement for designers to understand in depth the effects of propulsion drives on the ship network in different operating conditions. For this purpose computer simulations have proved to be a very useful tool. In the paper a typical propulsion drive for an all-electric cruise liner is described and simulation results are shown. Owing to the model complexity, simulations turn out to be computationally quite heavy. For this reason a simplified model has been developed. Simulation results, from the ship network viewpoint, proved to be close to the detailed model ones.

Neural network technique for the joint time-frequency analysis of distorted signal

Nonstationary distorted signals need to be analyzed in both the time and frequency domains to determine their characteristics. In this paper, a technique based on a neural network (NN) is presented which has the merit of providing such an analysis in real time. After arranging a suitable NN, the algorithm utilized to carry out the analysis is illustrated. Then, expressions assessing the dynamic behavior and the steady-state accuracy of the technique are derived. From the expressions, the influence of the NN parameters on the technique performance is readily recognized. As an example, the technique is applied to the analysis of the time evolution of the current harmonics absorbed by a diode rectifier and the results are compared with those obtained by the short-time Fourier transform.

Electric generation technologies for all-electric ships with Medium-Voltage DC power distribution systems

A promising solution to improve tomorrows all-electric ship onboard power system design and performance relies on moving from 50-Hz or 60-Hz AC distribution to a Medium-Voltage DC (MVDC) grid. This paper provides a review of presently-available and under-development technologies for electric generators to be used in perspective MVDC shipboard systems. The inspiring reason for the survey lies in the fact that an MVDC grid design removes the constraints usually imposed on shipboard generation group design and opens the way for a wide variety of non-conventional machine alternatives. In combination of high-speed gas turbines, that can be employed as prime movers, several electric machine topologies, not yet used for ship applications, can be selected to feed MVDC onboard systems. Along with a review of possible generator types suitable for such use, the paper critically reviews some emerging technologies for their fault-tolerance enhancement through conventional and innovative split-phase architectures.

Integrated voltage and reactive power control for all electric ship power systems

All electric ship alternators are connected to a main busbar which feeds all shipboard electric loads. To fulfill power quality requirements of the resulting electrical system, high-performance control of busbar voltage and frequency is needed. Such a task is not of easy accomplishment, due to the complexity of shipboard power station (generators are many and differ by sizes, prime movers, control systems, etc.) and to the intrinsic weakness of the shipboard grid. In this frame, a key power quality issue is voltage control. This paper presents an innovative shipboard voltage and VAR integrated regulator (WIRE). The WIRE controls main busbar voltage and jointly optimizes the reactive power generated by each alternator. It is designed to be interfaced with onboard automation and to realize the integrated management of all reactive power sources (rotating, capacitive, static). Furthermore it satisfies naval requirements as redundancy and fast commissioning

Dependability of safety-critical systems

Dependability, i.e. the capability of a system of delivering the expected service, is a fundamental requirement for safety-critical applications. It is becoming a very important matter in the automotive field. Indeed, car industries are planning to replace the traditional mechanical-hydraulic apparatus used for the execution of the driving commands with all-electric systems, the so-called drive-by-wire (DbW) systems, which are made of components that are not as reliable as the ones of the traditional apparatus. This paper, starting from the existing literature, provides at first a conceptual framework for the dependability topic. Then dependable architectures for DbW systems are presented. As a case of study, the steering maneuver is considered.

Power electronics for all-electric ships with MVDC power distribution system: An overview

Integrated Power Systems (IPS) with DC distribution require the massive use of power electronics for many tasks: 1) the output voltage rectification of generators and the connection of energy storage systems to the IPS, 2) the supply of medium voltage high power users (propulsion drives, bow thrusters, compressors for air conditioning), 3) the adjustment of voltage levels, which is performed by power transformers in AC distribution systems and by DC/DC power converters called Solid-State Transformers (SST) in DC distribution systems. In this paper, an overview is given of the power converters found in the literature and on the market that could be suitable for employment in the mentioned subsystems as parts of a future MVDC IPS. Finally authors propose a structure for an SST to be employed in three-wire MVDC power systems.

Feasibility and performance analysis of a high power drive based on four synchro-converters supplying a twelve-phase synchronous motor

In this paper a high-power electric drive based on a quadruple-three-phase synchronous motor and four load commutated inverters (LCI) is investigated to evaluate its feasibility and performance. Based on accurate simulation analyses, the advantages of the proposed solution compared to the technologically-proven dual three-phase scheme are highlighted in terms of torque quality and motor efficiency improvement.

All-electric Mega-Yachts: Integrated power system operation and its interaction with propulsion converters

More and more commercial and pleasure modern ships are equipped with electric propulsion system, which is the most important and power-consuming electric apparatus onboard. The significant increase in the power required onboard by the adoption of electric propulsion causes a great evolution in onboard power systems and poses the need for a proper development of design techniques and tools. At the same time, the traditional approach for onboard power system design based on experience and rules of thumb is becoming no longer adequate. This paper deals with this evolving scenery, and mainly concerns power system design and power quality aspects. Real data and measurements are provided with reference to a new-built mega-yacht. The work, in progress, aims to set up a complete electric model of the all-electric ship to allow simulation of different operating conditions and to predict the main power quality issues and the fulfillment of the relevant technical rules

An innovative photovoltaic field simulator for hardware-in-the-loop test of power conditioning units

In this work a review of photovoltaic (PV) field simulators and a project for the development of an innovative Hardware-In-the-Loop (HIL) PV field simulator are presented. The simulator is conceptually designed to be part of a future PV field demonstrator to be realized in the area of Trieste (Italy), which will include measurement facilities, networked PV fields, university laboratories and other research centers.