Extension of a Linear Optimal Control Strategy for HEV
2015 European Control Conference (ECC), pp. 154-159, 2015
Author(s): | Hahn S., Waschl H., Steinmaurer G., Del Re L. |
Year: | 2015 |
Month: | 7 |
Abstract: | Since the last decade, hybrid electric vehicles have
been and are introduced increasingly by automotive industry
as they provide substantial improvements in fuel consumption.
However, the optimal power distribution between the different
energy sources in a HEV to achieve high efficiency is a non
trivial problem. In a former work, an approximate solution to
the generic optimization task by a two-stage approach based on
linear programming and switching strategies was introduced,
which is extended within this work. First, the opportunity
to declutch and switch off the internal combustion engine
is considered, which extends the linear program to a mixed
integer linear program and leads to additional improvements
in fuel consumption. The second extension introduces a receding
horizon strategy that considers the current and a target state
of charge of the battery at the end of the horizon during
the top level optimization. Thus a complete knowledge of the
driving cycle is not required but only a prediction for a shorter
horizon. Furthermore, errors caused by model-plant mismatch
and prediction can be compensated by the SOC feedback.
Both extensions result in a minimum increase in computational
effort and allow to formulate the optimization as mixed integer
linear program and solve it by real-time capable solvers. As
application example a parallel hybrid electric vehicle with
realistic models of battery and powertrain and the opportunity
to declutch the internal combustion engine is considered. The
method and the proposed extensions are evaluated in simulation
and experimental in which satisfactory results could be achieved
in both cases. |