Srdjan Lukic

Energy Storage Systems for Transport and Grid Applications

Energy storage systems (ESSs) are enabling technologies for well-established and new applications such as power peak shaving, electric vehicles, integration of renewable energies, etc. This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies. Special attention is given to the different applications, providing a deep description of the system and addressing the most suitable storage technology. The main objective of this paper is to introduce the subject and to give an updated reference to nonspecialist, academic, and engineers in the field of power electronics.

Review of non-isolated bi-directional DC-DC converters for plug-in hybrid electric vehicle charge station application at municipal parking decks

There is a growing interest on plug-in hybrid electric vehicles (PHEVs) due to energy security and green house gas emission issues, as well as the low electricity fuel cost. As battery capacity and all-electric range of PHEVs are improved, and potentially some PHEVs or EVs need fast charging, there is increased demand to build high power off-board charging infrastructures. A charge station architecture for municipal parking decks has been proposed, which has a DC microgrid to interface with multiple DC-DC chargers, distributed renewable power generations and energy storage, and provides functionalities of normal and rapid charging, grid support such as reactive and real power injection (including V2G), current harmonic filtering and load balance. Several non-isolated bidirectional DC-DC converters suited for charge station applications have been reviewed and compared, as the major focus of this paper. Half bridge converter is a good candidate but it is difficult to maintain high efficiency in wide battery pack voltage range. A variable frequency pulse width modulation (VFPWM) scheme is proposed to mitigate this issue. Finally three-level bi-directional DC-DC converter is suggested to be employed in this application. A 10kW prototype verifies that 95.1–97.9% full load efficiency can be achieved in charging mode with 180–360V battery pack voltage. In addition, the inductor size is only one third of the half bridge counterpart, which is a great advantage for high power converters.

On Integration of Solid-State Transformer With Zonal DC Microgrid

The contribution of this paper has been focused on investigating a new microgrid architecture that integrates the solid-state transformer with zonal dc microgrids. By utilizing the dc and ac links of the solid-state transformer, both ac and dc networks can access the distribution system, which renders the coordinate management of the power and guarantees high power supply reliability. In addition, the presented system together with the proposed power management strategy can minimize the effect of newly established zonal dc microgrid to the existing power grid, of which promises a better stability. To this end, this paper takes the photovoltaic and battery as the typical renewable energy resource and energy storage device, and develops a simulation platform for system study. Simulation results are shown to demonstrate the feasibility of the proposal.

Cutting the Cord: Static and Dynamic Inductive Wireless Charging of Electric Vehicles

In this article, we have reviewed the state of the art of IPT systems and have explored the suitability of the technology to wirelessly charge battery powered vehicles. the review shows that the IPT technology has merits for stationary charging (when the vehicle is parked), opportunity charging (when the vehicle is stopped for a short period of time, for example, at a bus stop), and dynamic charging (when the vehicle is moving along a dedicated lane equipped with an IPT system). Dynamic wireless charging holds promise to partially or completely eliminate the overnight charging through a compact network of dynamic chargers installed on the roads that would keep the vehicle batteries charged at all times, consequently reducing the range anxiety and increasing the reliability of EVs. Dynamic charging can help lower the price of EVs by reducing the size of the battery pack. Indeed, if the recharging energy is readily available, the batteries do not have to support the whole driving range but only supply power when the IPT system is not available. Depending on the power capability, the use of dynamic charging may increase driving range and reduce the size of the battery pack.

ZCS

Inductive power transfer (IPT) is commonly used to transmit power from an extended loop (track) to a number of galvanically isolated movable pick-ups. To maximize the power transfer and minimize converter requirements, various compensation circuits have been proposed for both the track (primary) and the pick-up (secondary). This paper investigates the suitability of the LCC series-parallel compensation for IPT primary design. A new compensation-circuit design procedure is proposed that considers high-order current harmonics and results in inverter zero-current switching. The proposed compensation is compared with the classical compensation designed for zero phase angle between the inverter voltage and current fundamental components. Expressions for the bifurcation boundary, voltampere rating of reactive-compensation elements, and the current at the moment of switching are derived and analyzed. Analytical results are verified both via PSpice simulations and experimentally using a 1-hp MOSFET-based prototype.

LCC

PHEV/EV DC charging infrastructure attracts more and more attention recently. High power isolated bi-directional DC-DC converters provide galvanic isolation, V2G capability and reduce the cost and footprint of the system. Maintaining high power efficiency in wide vehicle battery pack voltage range is required. Three full bridge based high power bi-directional DC-DC converters are conceptually designed for this application and their advantages and disadvantages are addressed. Experimental test bench is built and efficiency evaluation for bi-directional operation is reported.

-Compensated Resonant Inverter for Inductive-Power-Transfer Application

In this paper the optimum design of a fast-charging station for PHEVs and EVs is proposed to minimize the strain on the power grid while supplying the vehicles with the required power. By studying the power demand of the charging station, a conclusion is reached that the size of the grid tie can be reduced substantially by sizing the grid tie for the average rather than the peak power demand. Therefore the charging station architecture with a single AC/DC conversion and a DC distribution to DC/DC charging units is proposed. An energy storage system is connected to the DC bus to supply power when the demand exceeds the average that can be provided from the grid. Various topologies for both the AC/DC and DC/DC conversion are studied to find the optimum design for this application.

Review of high power isolated bi-directional DC-DC converters for PHEV/EV DC charging infrastructure

There is a need for in-depth study of technologies that will affect the utility industry in a time horizon of less than 20 years. One such technology is the plug-in vehicle (PHEV); there is a need for energy management when a large number of plug-in hybrid vehicles penetrate the market. In this paper, we propose an “intelligent energy management system (iEMS)” that intelligently allocates power to the vehicle battery chargers through real time monitoring and control, to ensure optimal usage of available power, charging time and grid stability. We begin by conceptualization of the system architecture and description of its operation and provide a theoretical framework for system modeling. A detailed PHEV battery model and state of charge estimation algorithm are also being developed to simulate different PHEVs to be recharged at a municipal parking deck. We will present the simulator we have developed for representing the iEMS using Matlab/Simulink and discuss obtained results and future directions.

Optimum design of an EV/PHEV charging station with DC bus and storage system

A new bi-directional power converter for Plug-in Hybrid Electric Vehicles (PHEV) is proposed based on a typical household circuitry configuration. This converter can achieve three major functions: battery charger mode, vehicle to grid mode (V2G) and vehicle to home mode (V2H), which are the main topics of integration of PHEVs with the grid. The detailed converter design is presented. An improved AC/DC controller is proposed in order to achieve low input current harmonics for the charger mode. The Proportional resonant+harmonics selective compensation method is utilized for the V2G mode, and capacitor current feedback and proportional resonant control methods are adopted for the V2H mode. Compared with conventional PI controllers, the proposed controllers greatly enhance the grid-connected converters performance in the aspects of low harmonics output and robustness against background noise.

Intelligent energy management system simulator for PHEVs at municipal parking deck in a smart grid environment

A new multi-function bi-directional battery charger for plug-in hybrid electric vehicles (PHEV) is proposed based on the power circuitry configuration of an American house. This bi-directional charger can achieve three functions including battery charging, vehicle to grid (V2G) and vehicle to home (V2H), all of which are the major research areas of PHEVs integration with the power grid. The integration infrastructure and practical design issues are analyzed. The multiple control loop designs are presented for the three operation modes. Simulation and experimental results verify the functions and performance of the proposed charger. With the capability of achieving multiple functions, the bi-directional charger will contribute and enhance grid related research of PHEVs.