Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here.

In this paper a 22 kW on-board charger for electric or plug-in hybrid vehicles is proposed. To achieve high quantities of devices, a fully modular circuit and control structure is chosen. The circuit arrangement consists of three identical phase units (7.4 kW), which are comprised of two identical (3.7 kW) base units. The proposed charger is implemented and has a volume of 11.1 liters and a weight of 12 kg. The experimental result indicates an efficiency of more than 94 percent over the full battery voltage range at an input voltage of 230 Vac. The output voltage for full load and best efficiency varies from 315-395 V

The market breakthrough of electric vehicles is mainly delayed by the still too high costs of the battery system. The smart battery cell monitoring presented in this article enables further cost reduction. It consists of battery cells integrating the monitoring electronics together with a data transfer interface for communicating in a bidirectional way with the battery management system. The data transfer interface presented in this paper is based on a differential contactless data transmission bus using galvanically isolated capacitive coupled links to each single smart battery cell. Since neither galvanic contacts nor connectors are needed, the proposed concept provides simultaneously a very high level of reliability and robustness, and a highly cost-efficient manufacturing process, thus allowing a significant reduction of the final battery pack costs. This paper describes a possible implementation of such a differential contactless data transmission for monitoring and managing battery cells in electric vehicles. State-of-the-Art in Battery SystemsDespite the great efforts that have been made during the last years to promote electric mobility, the electrical vehicle still has not had its final breakthrough. An important reason for the lack of broad acceptance is the cost of electric vehicles (EV) that is still too high. Especially the battery system is and will remain a major cost factor in the near future. This article describes a novel approach to the battery system, which is aimed to significantly reduce the component costs, the development time and the manufacturing costs of the battery system, while increasing its flexibility and reliability.

In this paper a 3.7 kW On-board charger (OBC) for electric or plug-in hybrid vehicles is proposed. With regard to standardization, cost reduction and to increase the volume of produced devices, the OBC is derived from a fully modular circuit and control structure. The two-stage circuit arrangement consists of an isolated full bridge ZVS resonant converter and an interleaved boost converter for power factor correction (PFC). The proposed charger has a volume of less than 4 liters and a weight of 3 kg. The experimental result indicates an efficiency of more than 95 percent over the full battery voltage range at an input voltage of 230 Vac. The output voltage for full load and best efficiency varies from 315-395 V