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The paper proposes an energy efficiency analysis for an Ultra-Fast Charging Station (UFCS). The UFCS, realized at the DIETI Lab of the University of Naples Federico II, is equipped with two charging slots of 160 kW rated power, a grid-tied power converter of 50 kW and a Battery Energy Storage System (BESS). It is operated in Grid to Vehicle (G2V) mode using a peak-shaving strategy. The infrastructure uses two DC/DC power converters based on H-bridge, a medium frequency transformer, and diode rectifier architecture. The infrastructure is able to operate the two converters as a single or twin EV charging configuration, respectively. This paper focuses on the operating behavior of the power converters during the phases of EV fast charging. Analyses of energy efficiency have been carried out taking into account the switching and thermal behavior of the power converters. The validation of the analyses is performed through comparison with the numerical results obtained in PLECS environment. The proposed methodology is a viable tool to give support in designing UFCSs in terms of components and subsystems sizing.

Worldwide expectancy of larger fleets of PEVs requires an increasing number of available fast and ultra-fast charging stations. In order to reduce the impact on the distribution grid of the power demand of large fleets of PEVs, the coordination of charging in stations equipped with multiple charging slots is mandatory. The paper suggests a smart charging profile of electrical vehicles based on an optimization problem in order to minimize the charging time. Constraints in term of limits on the power supplied by DSO, the available state of charge (SOC) of the BESS and the energy requested by the PEVs are taken into account. Some simulations are presented to validate the suggested charging strategy.

Recently a great interest has been paid in the relevant literature to the use of energy storage systems for the performance improvement of electrified light transit systems. In this context, the main targets are the increase of the energetic efficiency and the reduction of pantograph voltage drops. Therefore, it can be very interesting the determination of the optimal characteristics of a storage device for satisfying these objectives, both in stationary and onboard case. In this paper, this problem is approached for a sample case study, by showing that the optimal design of a stationary storage device can be regarded as a classical isoperimetric problem, whose solution is very attractive in order to determine also the optimal allocation of the storage device. For more complex configurations of the transit system, the methodology presented can be extended by solving a constrained optimization problem, which in a quite general manner is capable of matching all the assigned technical requirements. The reported simulations confirm the validity of the proposed design approach.

The paper suggests the use of supercapacitors in the bridge crane AC drives application, as storage auxiliary device connected in parallel with the main power source for energy saving. A sizing procedure is proposed. The design procedure of the storage system is derived from theoretical considerations. It leads to evaluate the ratings of all devices capable of satisfying the load requirements. Numerical results are reported in order to show the feasibility of proposed technical solution and to evaluate the energy saving.

Abstract The paper deals with mathematical modelling and the control system for UltraFast Charging Stations (UFCS) based on DC micro-grid concept and Energy Storage System Integration to feed new Electrical Vehicles (EVs) at 800V DC in order to reach the EVs power requirement for charge-time less than 10 min. The UFCS integrates a battery energy storage system (BESS) to reduce the peak power of AC main grid, decoupling the dynamics of the DC charging station from the AC grid by means of its dedicated control system. Designing procedure and Control Strategy, based on Load Levelling power management, are dealt with numerical simulation results in Matlab-Simulink software, presented in order to verify UFCS performance and the charging station’s dynamics.

The paper deals with the power control of a delta connected Cascaded H-Bridge (CHB) converter equipped with photovoltaic (PV) modules. A hierarchical architecture of energy management is proposed: a “Module level” controller performs a Maximum Power Point Tracking (MPPT) algorithm to achieve the optimal utilization of each PV module; a “Leg level” controller manages the power flow control within the modules of a single CHB phase leg, and a “System” level controller manages the active power flow between the three CHB phases and the reactive power generation towards the grid. The active power control is aimed at the compensation of the mismatches between the different PV-powered modules, which may come from partial shadowing phenomena. A power unbalance compensation between cascaded modules is implemented through the Pulse Width Modulation (PWM) algorithm, while the unbalance compensation between the phases is implemented through the phase currents control. To compensate the active power unbalance due to PV module mismatches, the obtained effect is equivalent to the injection of a zero sequence current. A reactive power control has been implemented to perform a power factor (PF) correction, too. A set of numerical simulations validate the effectiveness of the algorithm, which can simultaneously achieve the desired active power generation from all the PV panels and the desired PF control towards the grid.

This paper proposes an innovative semi-two-stage topology for the traction system of trams equipped with supercapacitors, with the aim to downsize the onboard dc/dc converters. The configuration is obtained through a non-conventional connection of a half-bridge chopper and 3L Neutral Point Clamped (NPC) inverter to the dc sources and ac traction motors. By means of a proper modulation strategy, the NPC converter works as a Multi-Source Inverter and can independently control the power absorbed or supplied by the catenary and supercapacitors. Due to limitations in the power-processing domain of the NPC circuit, a chopper must be also included in the traction circuit. However, it processes only a fraction of the total power of the supercapacitors. The proposed solution is compared against a traditional two-stage architecture, where a dc/dc converter processes the entire power of the capacitors and a 2L Voltage Source Inverter drives the traction motors. Extensive numerical analyses testify that the envisioned architecture shows encouraging performance and can yield a significant reduction of the dc/dc converter ratings, losses, volume, and weight.

The paper deals with the control procedures for obtaining current harmonic compensation by active filters. It suggests a control technique based on very simple mathematical relationships and uses results previously obtained in performance analysis of active filters. The suggested theoretical procedure has been applied to a sample case for which theoretical and numerical results are given.

Abstract The installation of stationary ultracapacitor storage devices, as widely recognized, allows the recovery of the braking energy for increasing the energy efficiency as well as a better pantograph voltage profile. In the paper a new methodological mean is proposed for determining the fundamental characteristics of this kind of storage device, characterized by high power density, interfaced with the railroad by a bidirectional dc–dc converter. More specifically, the parameters of the storage system can be determined by employing an optimization technique which in a quite general way is able to take contemporaneously into account several aspects in an integrated manner. Some considerations are performed for properly taking into account the stochastic aspects of the design procedure. Numerical simulations with respect to a case study are presented, pointing out the potentiality of the tailored technique. Experimental results are also reported, with reference to an electromechanical simulator, in order to put in evidence the effectiveness and the actual implementation of the proposed optimization technique.