A premixed charge compression igriition(PCCI) combustien was simulated by the Large Eddy Simulation in coniunction with a reaction kinetics model. We analyzecl the interrelationships between mixture heterogeneity and reactien in a turbuleni flow. Several different initial conditions of heterogeneity of an air-fuel or air-fuel-EGR gas mixture weregiven at the intake valve closing time by a new method, which generated a statistically reasonable turbulent fiuctuations in both velocity and fuel mass fraction fields, The auto-igriition and combustion behaviors were analyzed for several different sets ofthe rrns and the iength scale of the fluctuations in fuel mass fraction, The analyses show that the equivalence Tatio fluctuations with 1arge rrns and length scale have considerable effect in attaining moderate comhustion in a PCCI engine.

A hybrid electric vehicle (HEV) that uses multiple planetary gear units with clutches as transmission system is advanced for the powertrain performance, because the operation of the clutches can lead to distinct operating modes, and the induced possible operating modes provide additional freedom to deal with the energy optimal control problem. Under each operating mode, the powertrain mechanical system has specific dynamical behavior. In order to develop model-based optimization schemes that can tackle the transient operations of the vehicle, exact dynamical modeling is investigated focusing on a hybrid powertrain system that uses a two-planetary-gear transmission box with two clutches. It shows that according to the states of the two clutches, the powertrain system has the power-split mode, parallel mode and the electric vehicle (EV) mode. Finally, an analysis for the calculation of the desired driving torque and its application to the dynamic programming (DP)-based energy management indicate the significance of the developed exact dynamical models. Citation Zhang J Y, Inuzuka S, Kojima T, et al. Dynamical model of HEV with two planetary gear units and its application to optimization of energy consumption. Sci China Inf Sci, 2019, 62(12): 222203, https://doi.org/10.

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We solve a optimization problem for HEV energy management. In this study, HEV system has three driving modes(EV, parallel, series parallel) with two motors, one engine and two clutches. We change this problem into a combination optimization problem by discretizing each torque as a variable. It is difficult to solve this problem because the combinations of variable are so many. To this hard problem, we solved it efficiently by using dynamic programming and applying steady-state approximation. It does not require much computation time, and a global approximate optimal solution can be obtained.

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