Control strategies for a spark ignition engine during the warm-up phase

Atmospheric pollution is an open problem that hits above all the cities. It is caused by different factors, as exhaust gas of the cars. To limit the emission level a three way catalytic converter is used to post-treat exhaust gases produced by combustion. The catalyst efficiency depends on the operating point; particularly during the warm-up phase the largest amount of pollutants is produced because the catalyst is not properly working. An appropriate control strategy is necessary during this phase in order to minimize dangerous emissions. In this paper, different innovative control strategies, designed for the warm-up phase, are presented. Firstly a simple controller, based on PI regulator, is compared with a more complex controller realized using the LQ technique. Finally, a secondary air injection on the exhaust manifold is considered and the two control strategies are implemented with this new control input.