Principle Guidelines for Safe Power Supply Systems Development

The relevance of safety applications within the automotive industry is increasing continuously, e.g. due to vehicle automation and decreasing relevance of mechanical backups. To cope with these trends, the power input of safety-related electrical and/or electronic systems needs to be ensured by the power supply system - leading to increased functional safety requirements. Compliance with ISO 26262 will be more in focus in the future. Currently, the compliance with ISO 26262 may be used to argue the state of the art focusing on product liability - however, it will become mandatory for homologation. Thereby, the power supply system is a crucial point since faults of the power supply system are currently the major contributor for vehicle breakdowns with increasing tendency. So far, there is no standard approach within the automotive industry how to ensure functional safety for power supply systems. To fill this gap, this technical elaboration evaluates functional safety with focus on power supply systems development. Hence, guidelines on how to apply the ISO 26262 are provided based on discussions within the automotive industry and research institutes. The focus is on the concept phase, i.e. item definition, hazard analysis and risk assessment, and the functional safety concept. The functional safety concept is based on a structured hierarchical breakdown to systematically derive safety requirements from the item level down to the power supply system level. The essential safety requirement - beside the safe power feed and safe power distribution - is to assure the freedom from interference between the safety and non-safety relevant components.