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The new generation of drive-by-wire systems currently under development has demanding requirements on the electronic architecture. Functions such as brake-by-wire or steer-by-wire require continued operation even in the presence of component failures. The electronic architecture must therefore provide fault-tolerance and real-time response. This in turn requires the operating system and the communication layer to be predictable, dependable and composable. It is well known that this properties are best supported by a time-triggered approach. A consortium consisting of German and French car manufacturers and suppliers, which aims at becoming a working group within the OSEK/VDX initiative, the OSEKtime consortium, is currently defining a specification for a time-triggered operating system and a fault-tolerant communication layer.1 The operating system and the communication layer are based on applicable interfaces of the OSEK/VDX standard.

As features in vehicles and their associated loading on the vehicle's power supply increase, the existing 14V power supply system is being pushed to its limits. At some point it will be necessary to provide a complementary higher supply voltage for higher power loads to ensure reliable operation. Industry efforts have been underway to define the next step(s) toward a common architecture. These efforts are currently focused on a dual voltage 14V/42V system with specified voltage limits. A change in the vehicle's power supply voltage and over-voltage specifications have a direct impact on semiconductors. Cost, reliability, available process technology, and packaging are among the areas that are affected. Reducing or eliminating the load dump transient can provide cost reduction, especially for power switching devices. Smart semiconductor switches with integrated diagnostic and protection features provide the potential to replace fuses in the new architecture.

Battery cell operating characteristics were determined for a unique load profile planned for the Motorola Iridium™ spacecraft. The Iridium™ mission requires that the battery be on line at all times and operated for extended periods with a short duration, high rate, charge/discharge duty cycle. The effort reported here reflects a repetitive duty cycle of 1.3 milliseconds discharge and 2.9 milliseconds charge, with discharge rates in the range 2.0 C to 3.0 C and charge rates in the range 0.9 C to 1.4 C. Cell transient characteristics were determined for candidate cell types including nickel-hydrogen individual pressure vessel (IPV), nickel-hydrogen common pressure vessel (CPV), Super nickel-cadmium, and fiber nickel-cadmium (FNC). Experimental approach, cell performance data, derived transient characteristics, and cell electrical models are presented.