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.

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.

This paper is an overview of fast charging for electrical vehicles. Specifically, it analyzes the impact of Ultra-Fast Charging Stations (UFCSs) on the distribution grid and their role in the smart grids. Moreover, the paper defines the framework of UFC, its diffusion and the associated new trends. The most frequently used converters in the conversion stages of DC charging stations with integrated generation are analyzed. To achieve this goal four active front end AC-DC converters (unidirectional and bidirectional), three isolated DC-DC converters as well as two control architectures are explored. In comparing the targeted configurations, the main target is set on categorizing them based on supply voltage level, type of smart grid, and power flow of the converters. Further, the paper outlines a broad overview of main standards for UFCSs and evaluation of the reliability, data collection, and operation of UFCSs. The paper aims to to link the needs of the designers of charging stations to preferences of the commercial market.

In this paper, an advanced control strategy for grid-tied photovoltaic (PV) cascaded H-bridge (CHB) inverter is proposed. The circuit topology consists of a proper number of power cells (H-bridge configuration) connected in series and supplied by individual PV modules. The adopted control method is a mixed staircase-PWM technique performed by means of a sorting algorithm to determine cells' switching state. The cells' state is related to the need of charging or discharging a particular cell much more than the others by calculating the voltage error at each dc-link (e.g., by considering the difference between the maximum power point tracking (MPPT) reference and the measured quantity). A dedicated P&O MPPT permits to control independently the voltage of each dc-link; thus, increasing the power extraction even in mismatched conditions. In order to prove the effectiveness and feasibility of the proposed approach, a set of experiments are performed on a laboratory prototype of a single-phase five-level PV CHB. The control section is implemented on FPGA by using a dSPACE real-time hardware platform; thus, obtaining fully dedicated digital circuits. Experimental results show good performance in terms of MPPT efficiency, total harmonic distortion, and power factor in both normal operation and mismatch conditions.

Despite low energy and fuel consumption levels in the rail sector, further improvements are being pursued by manufacturers and operators. Their primary efforts aim to reduce traction energy demand, replace diesel, and limit the impact of electrified overhead infrastructures. From a system‐level perspective, the integration of alternative energy sources on board rail vehicles has become a popular solution among rolling stock manufacturers. Surveys are made of many recent realizations of multimodal rail vehicles with onboard electrochemical batteries, supercapacitors, and hydrogen fuel cell systems. The ratings, technical features, and operating data of onboard sources are gathered for each application, and a comparison among different technologies is presented. Traction system architectures and energy‐control strategies of actual multimodal units are explored and compared with literature research. Moreover, the maturity and potential of recent technologies and alternative topologies of power converters for multimodal traction systems are discussed. Ultimately, onboard storage systems are compared with other solutions for energy‐saving and catenary‐free operation, with particular focus on their current techno‐economic attractiveness as an alternative to diesel propulsion.