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This paper investigates the combustion phasing control of natural gas-diesel engines. In this study, the combustion phasing is influenced by manipulating the start and the duration of the diesel injection. Instead of using both degrees of freedom to control the center of combustion only, we propose a method that simultaneously controls the combustion phasing and minimizes the amount of diesel used. Minimizing the amount of diesel while keeping the center of combustion at a constant value is formulated as an optimization problem with an equality constraint. A combination of feedback control and extremum seeking is used to solve this optimization problem online. The necessity to separate the different time scales is discussed and a structure is proposed that facilitates this separation for this specific example. The proposed method is validated by experiments on a test bench.

In this paper, we present an analysis of the optimal burn rate in an internal combustion engine (ICE) considering pressure gradient, maximum pressure, and knocking. A zero-dimensional model with heat losses is used for that purpose. The working fluids are assumed to behave like ideal gases with temperature dependent gas properties. In the first part, it is assumed that the burn rate can be arbitrarily chosen at every time instance in order to maximize the mechanical work. This leads to an optimal control problem with constraints. In the second part, a Vibe type burn rate is assumed, where the center of combustion, the duration and the form factor can be chosen in order to maximize the mechanical work. This Vibe type burn rate is finally compared with the arbitrary combustion as the benchmark in order to evaluate the potential of the more realistic burn shape.

In this paper we present an extension of the tank-to-wheel efficiency for hybrid electric vehicles. The energy at the wheel is split into dissipative energy and circulating energy. Instead of using one lumped tank-to-wheel efficiency, we use fuel-to-traction efficiency and recuperation efficiency. We further show that for a hybrid electric vehicle, fuel-to-traction efficiency and recuperation efficiency are almost constant and independent of the driving cycle. This fact makes our approach well suited for the estimation of the needed fuel energy for hybrid electric vehicles.

Adaptive feedforward control is a common approach for handling uncertainties and time-varying effects in automotive control applications. The adaptation of the feedforward controller, usually formed by a lookup table, is often combined with a linear feedback controller. The feedforward controller is used to overcome the nonlinearities that are due to variations of the operating point. The feedback controller is used to deal with fast disturbances. If the system behavior is changing, for example due to varying fuel qualities or aging effects, the feedforward controller has to be adapted. A common problem is the fact that the bandwidths of the feedback controller and the adaptation of the feedforward controller have to be separated, i.e. the adaptation of the feedforward controller has to be slower than the feedback controller. Otherwise, the coupling effects lead to an unexpected behavior of the control system, which may also lead to instability. This paper presents an analysis of this effect using a linear representation of the adaptation of the feedforward controller. Based on the results of this analysis, the paper presents a method to decouple the feedback controller and the adaptation of the feedforward controller, which allows a fast adaptation of the feedforward controller. Ideally, the adaptation is as fast as the feedback controller. The system is then able to adapt during operating point transients without the need to stay at some operating points for longer periods. The proposed method does not depend on the structure of the feedforward controller, nor does it depend on the method of the adaptation. Experiments on a natural gas–diesel dual-fuel engine are used to validate the proposed method.