On Board Diagnostics (OBD) for Multi Topology Hybrid Electric Powertrain Architectures 2018-01-1827

OBD is extended to electric powertrain components in Hybrid Electric Vehicle (HEV) architectures to monitor all components which influence vehicle emissions and electrical energy consumption. Besides main electric components, like battery, inverter, electric machines including their thermal management, other electric powertrain components and systems need to be evaluated as part of comprehensive component monitoring. The multiple possible HEV topologies require a complex assessment regarding the OBD relevance decisions of the electric drivetrain components or systems. In addition, specificities to OBD perimeter design in the hybrid architecture need to be appropriately chosen. This paper analyzes in detail the OBD regulation requirements for electric propulsion components as in the US regulation, which is an envelope for major global markets like Europe, China, Japan and Korea. Typical hybrid topologies from the literature and FEV’s comprehensive library are used as citation in this study. The monitors from these topologies are assessed for OBD relevance based on regulation requirements and the approach is detailed in this paper. The assessment is extended to safety relevant monitors, which are not part of traditional powertrain systems. The in-use performance ratio needs to be calculated for non-continuous monitors. The arithmetic between on-road driving, utility factor and frequency of non-continuous monitoring is also included. An efficient OBD development approach is elaborated for electric propulsion components in an HEV architecture. This covers requirement analysis, assessment approach for different types of input, output and functional monitors and concludes with an efficient validation approach.