Risks of Lightning to Automotive Occupants and Electrical/Electronic Systems 2017-01-0061
Lightning strikes on automobiles are usually rare, though they can be fatal to occupants and hazardous to electronic control systems. Vehicles’ metal bodies are normally considered to be an effective shield against lightning. Modern body designs, however, often have wide window openings, and plastic body parts have become popular. Lightning can enter the cabin of vehicles through their radio antennas. In the near future, automobiles may be integrated into the electric power grid, which will cause issues related to the smart grid and the vehicle-to-grid concept. Even today, electric vehicles (EVs) and plug-in hybrid vehicles (PHEVs) are charged at home or in parking lots. Such automobiles are no longer isolated from the power grid and thus are subject to electric surges caused by lightning strikes on the power grid. A charging system connected to an EV or PHEV should absorb the surge, but powerful lightning strikes can overwhelm the surge protection and intrude into the electric and electronic (E/E) systems of the vehicles, as often happens with household electrical equipment.
This paper discusses the increasing risks of lightning to automotive occupants and E/E systems. To demonstrate the risk to vehicle systems, artificial lightning was generated by a 3 MV-impulse voltage source and supplied to a test vehicle. Arcing at the vehicle’s metal joints was then observed; the electronic system of the instrument panel was destroyed in the experiment. The induced surge voltage and lightning current in the metal body were both measured to determine the impact on the vehicle’s electronic systems. In order to develop a theoretical model for vehicle lightning, a NiCr metal box was also examined under artificial lightning conditions. In these experiments, neither the vehicle’s metal body nor the NiCr box shielded the lightning well. During lightning strikes, significant voltage differences were observed in the metals, and the vehicle body did not work as a common ground. The voltage difference also suggested the generation of an electromagnetic field in the vehicle cabin that can be harmful to vehicle systems.