Energy Management for RCCI Engines with Electrically-Assisted Turbocharging

In this paper, Reactivity Controlled Compression Ignition (RCCI) with an electrically-assisted turbocharger (E-turbo) is investigated. This is a promising concept for future green transport, since it can realize very high thermal efficiencies for a wide range of renewable fuels. The combination of RCCI with an E-turbo requires a new approach to manage the energy flows of the engine due to constraints on the storage of electrical energy. The E-turbo shows most potential to increase the engine's thermal efficiency by improved tracking performance of the desired intake conditions. To exploit the full potential of the E-turbo during transients, a dynamic decoupling feedback controller is designed. A supervisory controller based on Pontryagin's Minimum Principle is composed to maximize the brake thermal efficiency while the battery of the E-turbo remains charge sustaining. The supervisory controller determines setpoints for the feedback controller and ensures therefore optimal engine operation during transients. For the simulated, real-world based transient-cycle, fuel savings of 0.64 [%] are realized by the developed supervisory control, while remaining charge sustaining.