Quantification of Plausibility Cross-checks (PCc) in safety critical systems for hybrid and electric vehicles

When analysing a high voltage isolation monitoring system for a hybrid or electric vehicle at the system architecture concept stage, close correlation can be demonstrated between the Plausibility Cross-check (PCc) quantification and the Single Point Fault Metric and Latent Fault Metric calculated during verification of the final design. The quantitative analysis method discussed, gives a high confidence level at the concept stage that the architecture selected is capable of achieving the safety goals and their associated Automotive Safety Integrity Level (ASIL) targets. The early adoption of an architecture capable of meeting the required ASIL targets will require fewer iterations in the detailed design phases of the lifecycle thereby reducing the likelihood of late design changes. The method has been applied in both new vehicle architectures and also the retrofit of an electric drive system into an existing diesel powered vehicle.