Deliverables

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D3.1 Causes and effects of the powertrain's failure modes

Executive Summary

This document outlines work carried out in the HEMIS project concerning:

• identification of possible failure mechanisms for the electrical transmission, comprising the electrical machine(s) and associated power electronics and controller;
• assessment of available data concerning the likely prevalence of such failures.

Based on a review of traction machine technologies either used in existing EV/HEV vehicles or proposed for impending EV/HEV developments, as well as input from the HEMIS Advisory Panel, three types of motor were selected for further analysis: the AC Permanent Magnet Synchronous Machine, the asynchronous AC Induction Machine and the Switched Reluctance Machine.The first two types were selected as they are already used in a wide range of hybrid/electric applications. The SRM is included as it is of current interest for a number of future vehicle projects.

Published information concerning failure rates in the electrical powertrain of FEVs is not readily available at present. Consequently, data regarding electrical machines (i.e. motors and generators) and power electronics converters used in other applications are considered here.

The purposes of these investigations were to:

• enable further refinement of the fault tree and failure mode, effects and criticality analyses initiated in WP2;
• support the development of Ishikawa (fishbone) diagrams;
• assist in the identification of physical parameters and analysis techniques that may be suitable for monitoring by the PHMS in WP4 and WP5.

Based on the hazard analyses carried out in WP2, potential functional failure mechanisms of a generic electrical powertrain were analysed using fault tree and failure mode, effects and criticality analyses. The FMECA approach provided a mechanism for identifying and prioritizing those failure modes that are considered to require corrective action in order to ensure that functional safety targets are satisfied.

Ishikawa diagrams were used to develop an overview of how electrical powertrain faults contribute to the vehicle-level functional safety hazards, providing a structured representation of all causes that could contribute to produce the undesirable effect. This approach provides a graphical representation of the relationships between all of the potential causes, from which one is more readily able to identify the root causes of the problem. Fault tree analysis was also used, in order to record the logical relationships between the faults that may contribute to the vehicle level hazards. These deductive (top-down) analysis methods provide complementary views of the failure mechanisms, and combining these techniques with the inductive (bottom-up) FMECA approach helps to ensure the overall completeness of the analysis.

For automotive applications, sophisticated signal processing techniques may be needed to overcome the wide variations in operating conditions that result during driving. Combining results from a number of different sensors, analysed using a number of different processing techniques, is expected to improve the scope and reliability of condition monitoring for electrical powertrain components, as well as enhancing the associated prognosis capabilities.

 

 

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Project acronym:
HEMIS

Project name:
 Electrical powertrain Health Monitoring for Increased Safety of FEVs


Project reference:
FP7-ICT-314609

Start date: 01/06/2012
End date: 28/02/2015


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