Depletion of fossil fuel reserves, increasing awareness of air pollution levels and continuous rise in gasoline prices are some of the major drives that have been revolutionizing the automotive industry since the last decade. These factors combined are causing conventional automobiles with internal combustion engines (ICE) to be replaced with plugin vehicles. The on-board rechargeable battery packs in plugin vehicles can be recharged by connecting to the utility grid using a plug. The energy stored in the on-board battery packs has attractive benefits for grid support, and this promotes the idea of Vehicle-to-Grid (V2G). V2G power transactions allow energy from the on-board battery packs to be sent back to the utility grid for support in peak shaving and provide reactive power compensation. One natural consequence that arises with the introduction of V2G is a sharp increase in the need for high-performance power electronic interface between the utility grid and the battery pack. Therefore, research on bidirectional battery chargers for plugin vehicles is imperative in order to aid in the promotion of V2G. This thesis focuses on the design and development in a two-stage level-two on-board bidirectional battery charger.

Depletion of fossil fuel reserves, increasing awareness of air pollution levels and continuous rise in gasoline prices are some of the major drives that have been revolutionizing the automotive industry since the last decade. These factors combined are causing conventional automobiles with internal combustion engines (ICE) to be replaced with plugin vehicles. The on-board rechargeable battery packs in plugin vehicles can be recharged by connecting to the utility grid using a plug. The energy stored in the on-board battery packs has attractive benefits for grid support, and this promotes the idea of Vehicle-to-Grid (V2G). V2G power transactions allow energy from the on-board battery packs to be sent back to the utility grid for support in peak shaving and provide reactive power compensation. One natural consequence that arises with the introduction of V2G is a sharp increase in the need for high-performance power electronic interface between the utility grid and the battery pack. Therefore, research on bidirectional battery chargers for plugin vehicles is imperative in order to aid in the promotion of V2G. This thesis focuses on the design and development in a two-stage level-two on-board bidirectional battery charger.

Making electricity grids smarter and facilitating them with integration of renewable energy sources (RES) and energy storage are fairly accepted as the necessary steps to achieve a sustainable and secure power industry. To enable Net-zero energy and optimize power management for future homes or buildings, DC electric distribution systems (DC Nano-grid) find feasibility and simplicity for integrating renewable energy sources and energy storage. However, integrating the sources and loads in a simple, robust and smart way is still challenging. High voltage lithium-ion battery should be seriously considered concerning the overcharge/over-discharge risk. Dissipative cell equalization and its performance are studied. Non-dissipative equalization methods are reviewed using an energy flow chart. Typical charging schemes and the related over-charge risk are illustrated. A Lithium-ion battery charging profile based on VCell_Max/Min monitoring is proposed and validated with experimental results in an 8.4kW bidirectional battery charger for DC future home. For the DC future home emulator testbed, a grid interface converter, i.e. energy control center (ECC) converter, is reviewed with functions identification. A PV system with different configurations is compared to further expand the common MPPT region, and a DC-DC converter is designed as the interface between PV panels and DC bus, facilitating maximum power point tracking (MPPT) as well as fulfill the system energy management requirement. An 8.4kW multi-phase bidirectional battery charger with Si IGBT in DCM operation is designed to achieve high efficiency and to be the interface converter between lithium-ion battery and DC bus, enhancing the battery system management as well as increasing the system reliability. To integrate all the sources and loads in a simple, reliable and smart way, this thesis proposes a distributed droop control method and smart energy management strategy to enhance the Net-zero electric energy cost. All of the control strategies are applied to the DC future home with interactions among the energy control center (ECC), renewable energy sources, energy storage and load within a day/24 hours. System level energy management control strategies for Net-zero electric energy cost are examined and illustrated. A 10kW future home emulator testbed is built and introduced for concepts validation. / Master of Science