Energy management of HEVs – fuel optimal control
A plug-in hybrid vehicle driving along a frequently recurring route should be able to decide by itself when it is optimal to use the battery. Such a strategy could be much more energy efficient than the conventional way of first depleting the battery and then proceeding with charge sustaining operation. PhD student Viktor Larsson investigates how to minimize the energy consumption by letting the vehicle autonomousy identify the route and calculate when the battery should be used.
– The coming route can be identified either using the GPS-based navigation system or the vehicle could try to identify the route autonomously using historical driving patterns. Next, an optimization problem is solved to determine when the battery should be used, explains Viktor Larsson. He continues:
– The aim of my research is to find out to which degree energy consumption can be reduced by using optimal control strategies based on a simple model of the hybrid electric powertrain. I hope that this knowledge will increase the understanding in both industry and academy of how optimal control can be used for hybrid electric drivelines.
The researchers have produced a method for automatic recognition of recurring routes from logged driving data, and to precompute optimal control strategies for these routes. In addition, Viktor Larsson has developed methods to render the computations more effective in terms of computation time and memory requirements.
-There has been a good deal of research in this area during the last ten years, but nevertheless we have managed to produce results with news value, says Bo Egardt, supervisor of the project. He continues that despite the use of relatively well-known methods, the research offers many challenges, such as the level of detail in the models or mathematical formulations of practically relevant problems.
The research is conducted in close collaboration with the industry, and the algorithms developed by Viktor Larsson will be tested on a plug-in hybrid vehicle at Volvo Cars during fall 2013.
Viktor Larsson held his dissertation in 2014.
Further reading: Logged driving route can reduce energy consumption by 10 percent >>
Download the final report: Energy management of HEVs - Fuel optimal control (235 KB)
Larsson V, Johannesson L, Egardt B. Impact of trip length uncertainty on optimal discharging strategies for PHEVs. In: Proceedings of the 6th IFAC AAC. Munchen; 2010.
Larsson V, Johannesson L, Egardt B. Influence of State of Charge estimation uncertainty on energy management strategies for Hybrid Electric Vehicles. In: Proceedings of the 18th IFAC World Congress.; 2011.
Larsson V, Johannesson L, Egardt B. Benefit of Route Recognition in Energy Management of Plug-In Hybrid Electric Vehicles. In: Proceedings of the American Control Conference.; 2012.
Larsson V, Johannesson Mårdh L, Egardt B. Cubic Spline Approximations of the Dynamic Programming Value Function in HEV Energy Management Problems. Accepted to the Workshop for New Energy Vehicle Dynamic System and Control Technology. Bejing, China; 2013.
Larsson V, Johannesson L, Egardt B. Comparing Two Approaches to Precompute Discharge Strategies for Plug-in Hybrid Electric Vehicles. Accepted to the 7th IFAC AAC.; 2013.
Larsson V, Mårdh LJ, Egardt B, Karlsson S. Commuter Route Optimized Energy Management of Hybrid Electric Vehicles. Submitted to Intelligent Transportation Systems. 2013.