Diego Iannuzzi

Speed-Based State-of-Charge Tracking Control for Metro Trains With Onboard Supercapacitors

This paper suggests a novel energy management control algorithm for metro trains based on speed measurement and acceleration estimation. The aim of the control is to recover in a supercapacitor (SC) storage device the maximum energy regenerated during train electrical braking and to limit the contact line peak current. The energy management control is integrated with the motor drive control, since discharge and charge of SC are connected to motoring and braking operations of the train. The algorithm is based on two nested loops on voltage and current of SC. The voltage and current references are calculated on the basis of the estimation of the train inertial force and acceleration, taking into account the power losses of the system. A simplified mathematical model of the whole electrical drive has been developed and the main features of the control strategy have been presented. Numerical simulations show the efficacy of suggested control and the energy saving obtained for metro trains. Experimental tests made on an electromechanical simulator fully confirm theoretical results.

Improvement of Energy Efficiency in Light Railway Vehicles Based on Power Management Control of Wayside Lithium-Ion Capacitor Storage

The paper suggests an energy management control strategy of wayside Li-ion capacitor (LiC) based energy storage for light railway vehicles (LRV). The installation of wayside supercapacitor (SC) storage devices, as widely recognized, allows the recovery of the braking energy for increasing the system efficiency as well as a better pantograph voltage profile. A new type of SC, LiC, interfaced with dc-interleaved converter has been presented. This technology has an energy density comparable to batteries and power density much higher than the batteries. The authors propose a control strategy based on the maximum kinetic energy recovery throughout braking operations of the running vehicles. The stored energy comes back to the vehicles during the accelerations. The strategy stays on the knowledge of the state of charge of LiC device and the actual vehicle speeds. In particular, the control algorithm evaluates, in real time, the actual value of LiC voltage and current references on the basis of the vehicles inertial forces and acceleration estimations, taking into account the power losses of the system. Experimental tests made on electromechanical simulator, equipped with a 136-V, 30.5-F LiC module, fully confirm the validity of the suggested control. Finally, experimental characterization of LiC module has been achieved.

Metro trains equipped onboard with supercapacitors: A control technique for energy saving

The paper suggests a control technique for improving energy saving in metropolitan trains equipped by onboard supercapacitors. On the basis of the typical duty-cycle of a metro-train, the supercapacitor system has been sized with reference to an energetic criterion that tries to limit overhead line current and, consequently, voltage drop at the train pantograph. The control algorithm is then based on a changeover scheme that properly manage the charge and discharge of supercapacitors in order to keep constant the line current during acceleration, coasting and braking of the train. Experimental results on a scale model, reproducing forces and inertias of a real railroad vehicle, validate completely both the sizing procedure and the control technique proposed.

Charging infrastructures for EV: Overview of technologies and issues

This paper presents an overview of issues and technologies related to the proper design of charging infrastructures for road electric vehicles. The analysis is carried out taking into account that the recharging stations of electric vehicles might be integrated in smart grids, which interconnect the main grid with distributed power plants, different kinds of renewable energy sources, stationary electrical storage systems and electric loads. The study is introduced by an analysis of the main characteristics concerning different kinds of storage systems to be used for stationary and on-board applications. Then, different charging devices, modes and architectures are presented and described showing their characteristics and potentialities. DC and AC configurations of charging stations are compared in terms of the issues related to their impact on the main grid and the design of their main components. Specific attention was devoted also to the ultra-fast DC architecture, which appears a possible solution to positively affect a wide spread of plug-in hybrid and full electric road vehicles.

High performance control technique for unbalanced operations of single-vsi dual-PM brushles motor drives

The paper deals with isotropic PM-brushless drives in configuration “single-inverter, dual-motor” operating with unbalanced load-torques. After a short review of some control techniques based on the classical control methodologies of single-motor PM drives, an innovative control algorithm is presented. It is suitable to minimize the resultant armature current needed to obtain an assigned resultant motor torque, whatever is the load unbalance. Simplified analytical expressions are given in order to quickly evaluate optimized reference currents with good approximation. From these reference values, a predictive feeding algorithm evaluates the reference voltage space-vector for the inverter supplying the two motors in parallel. Current and torque oscillation, torque/current ratio, dynamic response and stability are the mainly observed quantities. Effectiveness of proposed control technique is highlighted.

A power traction converter based on Modular Multilevel architecture integrated with energy storage devices

In this paper a power converter based on a modular multilevel topology integrated with energy storage devices for directly supplying of traction motors is discussed. The Modular Multilevel Converter (MMC) is one of the emerging technology for high- or medium- voltage transformerless power conversion. The possibility to directly control the traction motors by means of a dc/ac MMC topology, using also integrated energy storage systems (ESS) for recovering the kinetic energy, is exploited. Furthermore, a simplified mathematical model of the MMC with integrated ESS has been developed in order to evaluate the behavior of the traction unit during a typical load-cycle. The control law of the traction motor, integrated with energy storage flow management, has been introduced. The numerical results reported in the paper permit to confirm the feasibility of the proposed design and control strategy for light travel vehicle.

A sample application of supercapacitor storage systems for suburban transit

The advance in energy storage technologies allows to improve significantly the performances of electrified light transportation systems. This is aligned with the massive requirement of competitiveness compared to other transportation technologies in terms of sustainable energy and high reduction of environmental impact. The installation of stationary storage devices, as widely recognized, allows the recovery of the braking energy for increasing the energy efficiency as well as lower line voltage drops. In the paper, the storage system under investigation is based upon a bidirectional dc-dc converter with supercapacitors, characterized by high power density. The main parameters of the storage system are determined by employing an optimization technique, which in a quite general way is capable of taking into account contemporaneously several aspects in an integrated manner. Some simulations of lines of a suburban railways in Southern Italy managed by Sepsa Company are presented, pointing out how supercapacitors can be practically designed with the proposed technique.

Optimized control technique of single inverter dual motor AC-brushless drives

The paper deals with controlled PM-brushless drives in configuration ldquosingle-inverter, dual-motorrdquo operating with unbalanced loads at the shafts of the two motors. Some control techniques are analyzed and their relevant features are compared. Starting from some simple control circuits which refer to an equivalent ldquosingle-inverter, single-motorrdquo configuration, some compensation blocks are added in order to improve steady-state and transient performances. Current and torque distortion, total efficiency, dynamic response and stability are the main quantities observed. Their values are compared in order to evidence the advantages of the different examined control techniques.

A novel PV-modular multilevel converter for building integrated photovoltaics

The paper suggests a novel architecture of PV-powered Modular Multilevel Converter for building integrated photovoltaics. A grid-tied single-star configuration has been proposed. In particular, three different cell topologies have been analyzed and compared in terms of number of PV modules and rated voltages of semiconductor devices. Finally, a control strategy has been suggested in order to deliver to the grid the maximum power available from the PV modules at unity power factor.

Energy management of electrified mass transit systems with Energy Storage devices

In the paper a methodology for optimal controlling storage devices at the aim of improving the performances of an electrified mass transit system is proposed. A rational procedure is arranged for counteracting the unavoidable stochastic variables involved in the description of the characteristics of this complex system. The core of the control procedure is based upon an optimization technique which should result particularly effective where plant parameters exhibit random behavior. The potentiality of the procedure is shown with reference to the reduction of the network power fluctuations. In this case the control law can be expressed in an analytical way in terms of power mean value over the interest time cycle. Kalman filter is employed to dynamically estimate the mean value of the total required power. A numerical application is reported so to demonstrate the feasibility and the goodness of the proposed control strategy.