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In power-split configuration, the input power is split into two parts, one of which is transmitted from the internal combustion engine through one or more planetary gear(s) to the wheels. The other part is generated as electricity and passes through an electrical variator to assist the driving torque. The latter has the characteristic of poor efficiency. In this simulation study, a comparison among the input power-split, compound power-split, and two mode power-split are discussed. Output power-split is not mentioned in this paper due to its limited applicability in specific vehicles. The idea of selection of the electrical machines is explained: the speed and torque of electrical machines was taken into consideration for the required transmission ratios spread.

As a consequence of reduced fuel consumption, direct injection gasoline engines have already prevailed against port fuel injection. However, in-cylinder fuel homogenization strongly depends on charge motion and injection strategies and can be challenging due to the reduced available time for mixture formation. An insufficient homogenization has generally a negative impact on the combustion and therefore also on efficiency and emissions. In order to reach the targets of the intensified CO2 emission reduction, further increase in efficiency of SI engines is essential. In this connection, 0D/1D simulation is a fundamental tool due to its application area in an early stage of development and its relatively low computational costs. Certainly, inhomogeneities are still not considered in quasi dimensional combustion models because the prediction of mixture formation is not included in the state of the art 0D/1D simulation.

The software design of this new engine control unit is based on a unique and homogenous torque structure. All input signals are converted into torque equivalents and a torque coordinator determines their influence on the final torque delivered to the powertrain. The basic torque structure is independent on the type of fuel and can be used for gasoline, diesel, or CNG injection systems. This allows better use of custom specific algorithms and facilitates reusability, which is supported by the graphical design tool that creates all modules using automatic code generation. Injection specific algorithms can be linked to the software by simply setting a software switch.