Härtill 5 uppsatser

Diss. (sammanfattning) Göteborg : Chalmers tekniska högskola, 2021

It is well-known that the carbon dioxide gas generated by burning fossil fuels in automobiles contributes to climate change. This is however not their only exhaust and they also generate other troublesome gases; primarily carbon monoxide, nitrogen oxides, and small amounts of partially burnt fuel. These gases in turn contribute to smog, heart and lung conditions, cancer, and other diseases. These toxic emissions are a byproduct of the combustion process and unavoidable even when non-fossil fuels are used. The Three-Way Catalyst (TWC) is one component that can be used to reduce the level of harmful emissions by converting them to non-toxic carbon dioxide, water, and nitrogen gas. The TWC has been very effectively utilized, and can under ideal conditions eliminate nearly all the emissions from gasoline engines. However, the TWC is only effective at removing these emissions when sufficiently hot. This leads to a large initial release of emissions every time the engine is started with a cold TWC. This thesis focuses on the intersection of optimal control methods and dynamic modeling with the goal of reducing the generated emissions and consumed fuel, particularly in hybrid vehicles. This thesis introduces new variants of general optimal control methods as well as models of the dynamics found in the TWC and hybrid vehicle engines. Using these methods with the developed models allows both for constructing controllers that reduce the level of emissions generated during cold-starts as well as reducing the fuel consumption during changes in the engine’s speed. The presented controllers can in the future be implemented in production vehicles, as they do not require any complex calculations to be performed.