Over-actuated fault-tolerant hybrid electric vehicles
Drivelines containing power electronics and electric machines can indirectly affect passenger safety. How can we learn more about the behavior of electrified vehicles during electrical faults, and increase the reliability? These are questions that PhD student Daniel Wanner tries to answer.
– With my research, I want to contribute to an increased safety of electric vehicles, he says. I want to help reducing the severity of vehicle crashes due to technical failures and even avoiding potential vehicle crashes in order to decrease the amount of fatalities and injuries.
The researchers are putting particular focus on HEV concepts where the propulsion power is obtained from light in-wheel motors at each wheel. By classifying and analyzing risks and failure modes, they can predict possible consequences in the dynamic behavior of the vehicle, caused by the identified faults. By analyzing these consequences, it is possible to develop solutions to handle such faults. For example, if the propulsion power suddenly vanishes from one wheel of a vehicle, proper control of the remaining wheels can maintain the stability.
Above: A vehicle with and without fault-tolerant control strategy. When a fault occurs leading to a failure braking the rear left wheel, only the vehicle with fault-tolerant control (green trajectory) keeps stable, avoiding an accident.
– Analyzing the results and drawing conclusions from them is the most fun part of the work, says Daniel Wanner. Now we can rank faults that can occur in a vehicle according to how dangerous a fault would be for the driver, the passengers and other traffic participants.
To predict the vehicle behavior for different control strategies during failure modes, the researchers make detailed simulations using high fidelity vehicle models and transient fault models of the electric drivetrain based on the specified motor design. A scaled down prototype vehicle is also used for verifying measurements of the level of fault tolerance for various vehicle control algorithms.
-The optimal outcome of my research would be that the results are actively used by other people, as a guideline for OEM and suppliers, or in education or for further research, says Daniel Wanner.
Daniel Wanner defended his thesis in 2015.
Further reading: New control strategy reduces risk of accidents for electric cars >>
Download the final report: Over actuated fault-tolerant HEVs (272 KB)
D. Wanner, J. Edrén, O. Wallmark, M. Jonasson, L. Drugge and A. Stensson Trigell, Fault-tolerant control of electric vehicles with in-wheel motors through tyre-force allocation, in proceedings of the 11th International Symposium on Advanced Vehicle Control, 2012
D. Wanner, A. Stensson Trigell, L. Drugge, and J. Jerrelind, Survey on fault-tolerant vehicle design, in proceedings of the 26th Electric Vehicle Symposium, 2012. Download poster (pdf 1,6 MB) Word cloud (png 164 kB)
D. Wanner, Fault-Tolerant Over-Actuated Hybrid Electric Vehicles, KTH Transport Day, 2011. Download poster (pdf 990 kB)