Impact of Engine Dynamics on Optimal Energy Management Strategies for Hybrid Electric Vehicles
In recent years, rules and regulations regarding fuel consumption of vehicles and
the amount of emissions produced by them are becoming stricter. This has led
the automotive industry to develop more advanced solutions to propel vehicles to
meet the legal requirements. The Hybrid Electric Vehicle is one of the solutions
that is becoming more popular in the automotive industry. It consists of an electrical
driveline combined with a conventional powertrain, propelled by either a
diesel or petrol engine. Two power sources create the possibility to choose when
and how to use the power sources to propel the vehicle. The strategy that decides
how this is done is referred to as an energy management strategy. Today most
energy management strategies only try to reduce fuel consumption using models
that describe the steady state behaviour of the engine. In other words, no reduction
of emissions is achieved and all transient behaviour is considered negligible.
In this thesis, an energy management strategy incorporating engine dynamics
to reduce fuel consumption and nitrogen oxide emissions have been designed.
First, the models that describe how fuel consumption and nitrogen oxide emissions
behave during transient engine operation are developed. Then, an energy
management strategy is developed consisting of a model predictive controller
that combines the equivalent consumption minimization strategy and convex optimization.
Results indicate that by considering engine dynamics in the energy
management strategy, both fuel consumption and nitrogen oxide emissions can
be reduced. Furthermore, it is also shown that the major reduction in fuel
consumption and nitrogen oxide emissions is achieved for short prediction horizons.
Andreas Hägglund and Moa Källgren
Senast uppdaterad: 2021-11-10