Diagnostic Method Combining Look-up Tables and Fault Models Applied on a Hybrid Electric Vehicle
A common situation in industry is to store measurements for different
operating points in the lookup tables, often called maps. They are
used in many tasks, e.g., in control and estimation, and therefore
considerable investments in engineering time are spent in measuring
them which usually make them accurate descriptions of the fault-free
system. They are thus well suited for fault detection, but, however,
such a model cannot give fault isolation since only the fault free
behavior is modeled. One way to handle this situation would be also to
map all fault cases but that would require measurements for all faulty
cases, which would be costly if at all possible. Instead, the main
contribution here is a method to combine the lookup model with
analytical fault models. This makes good use of all modeling efforts
of the lookup model for the fault-free case, and combines it with
fault models with reasonable modeling and calibration efforts, thus
decreasing the engineering effort in the diagnosis design. The
approach is exemplified by designing a diagnosis system monitoring the
power electronics and the electric machine in a hybrid electric
vehicle. An extensive simulation study clearly shows that the approach
achieves both good fault detectability and isolability performance. A
main point is that this is achieved without the need for neither
measurements of a faulty system nor detailed physical modeling, thus
saving considerable amounts of development time.
Christofer Sundström, Erik Frisk and Lars Nielsen
IEEE Transactions on Control Systems Technology,
2016
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