Kambiz Morteza Ebrahimi

Repeatable steady-state measurement of particulate number emissions in engine experiments

Particulate number count is an important consideration for engine developers due to changes in emissions legislation. Changes are driven by an increasing body of evidence that particulate number, particularly smaller particles, have a deleterious effect on human health. This article presents the results of an investigation into the key factors influencing particulate number emissions measurement repeatability during dynamometer-based testing of a gasoline direct-injection engine. At the outset of this work, a review of literature summarises some of the current discussion concerning particulate formation, evolution and measurement to identify the key factors that influence these three things. Having established what these factors are a number of engine experiments are undertaken to determine how sensitive particulate number measurements are to change in these factors and therefore how great an influence they are on measurement repeatability in engine experiments of a similar type. The investigation highlights a number of important results, showing that particular regard ought to be given to the pre-conditioning of engine internal surfaces which begins when the engine is started. In addition, the effect of coolant temperature (including the dynamics of the control system) is observed and highlighted as another key source of variation as is intake air temperature.

Nonlinear Recursive Estimation With Estimability Analysis for Physical and Semiphysical Engine Model Parameters

A methodology for nonlinear recursive parameter estimation with parameter estimability analysis for physical and semiphysical engine models is presented. Orthogonal estimability analysis based on parameter sensitivity is employed with the purpose of evaluating a rank of estimable parameters given multiple sets of observation data that were acquired from a transient engine testing facility. The qualitative information gained from the estimability analysis is then used for estimating the estimable parameters by using two well-known nonlinear adaptive estimation algorithms known as extended Kalman filter (EKF) and unscented Kalman filter (UKF). The findings of this work contribute on understanding the real-world challenges which are involved in the effective implementation of system identification techniques suitable for online nonlinear estimation of parameters with physical interpretation.

Dynamic Modeling of a Transient Engine Test Cell for Cold Engine Testing Applications

The increasing complexity in the development and manufacturing process of internal combustion engines leads to a higher demand for more effective testing and monitoring methods. Cold engine testing becomes progressively the main End-of-Line test which is used nowadays from automotive engine manufacturers with the purpose of determining the integrity of engine assembly. The present work is focused on the development of a detailed physics-based, lumped-parameter, dynamic model of a single cylinder internal combustion engine coupled with an alternating current transient dynamometer for cold engine testing applications. The overall transient engine test cell model is described based on a two-inertia system model consisting of the engine, the dynamometer and the coupling shaft. The internal combustion engine is modelled based on First Law of Thermodynamics and Second Newton’s Law for rotational bodies. The transient dynamometer is actually an alternating current three-phase induction motor which is modelled according to direct-quadrature axis approach, and its drive unit which is responsible for controlling the speed of the motor using indirect field orientation scheme. The engine and dynamometer are connected through a coupling shaft which is modelled as a compliant member with damping. The model is validated against experimental measurements such as engine cylinder pressure, engine excitation torque and alternating currents of the induction motor. All of the experimental measurements were recorded from an identical single cylinder transient engine test cell using a highly advanced instrumentation system. The described model serves as an ideal platform for developing innovative model-based fault detection and diagnosis techniques for cold engine testing applications. In conclusion, this is presented successfully for two simulated fault cases, a process fault and a sensor fault, proving the functionality and usefulness of the model.Copyright

Model-based comparison of hybrid propulsion systems for railway diesel multiple units

ABSTRACT In order to reduce operating costs, railway vehicle operators need to find technical solutions to improve the efficiency of railway diesel multiple units on non-electrified railway routes. This can be achieved by hybridization of diesel multiple unit propulsion systems with electrical energy storage systems to enable brake energy recuperation. After highlighting the state of the art of hybrid railway vehicles and electrical energy storage systems, a simulation model of a generic diesel multiple unit in a 3-car formation is developed and equipped with three types of hybrid power transmissions. Simulations on realistic service profiles with different driving strategies show the potential for fuel consumption reduction for the different transmission types. On a suburban service profile, a 3-car diesel multiple unit is able to achieve simulated fuel savings of up to 24.1% and up to 18.9% on a regional service profile.

MIMO (Multiple-Input-Multiple-Output) control for optimising the future gasoline powertrain - A survey

This paper surveys publications on automotive powertrain control, relating to modern GTDI (Gasoline Turbocharged Direct Injection) engines. The requirements for gasoline engines are optimising the airpath but future legislation suggests not only a finely controlled airpath but also some level of electrification. Fundamentals of controls modelling are revisited and advancements are highlighted. In particular, a modern GTDI airpath is presented based on basic building blocks (volumes, turbocharger, throttle, valves and variable cam timing or VCT) with an example of a system interaction, based on boost pressure and lambda control. Further, an advanced airpath could be considered with applications to downsizing and fuel economy. A further electrification step is reviewed which involves interactions with the airpath and requires a robust energy management strategy. Examples are taken of energy recovery and e-machine placement. Control-oriented models of gasoline engines are reviewed, and challenging control problems for conventional engines and hybrid vehicle powertrains are discussed, in particular relating to consideration of the complex interactions. A systems approach is needed to understand the attribute trade-off, with fuel consumption, emissions, as well as energy storage on a particular drive cycle. This necessitates an optimisation methodology and appropriate problem formulation of objective, states and constraints. A discussion of optimisation techniques is considered. Finally, a comprehensive list of references is provided.

A hybrid model for a drilling process for hydrocarbon well-boring operations

In hydrocarbon well-drilling operations, self-excited, stick-slip vibration is considered as a source of drilling equipment failures, which also causes a reduction in the drilling penetration. This leads to delays and increase in the operational and equipment costs. A new approach using distributed-lumped (hybrid) modelling is considered as the first step in understanding the stick-slip phenomena in order to determine a solution to this problem. In this paper, a hybrid modelling scheme is the advocated modelling method proposed in contrast to the conventional lumped modelling. Three case studies are used to show that hybrid modelling is an accurate technique in the representation of stick-slip oscillations, particularly when the length of the drill string is high. The results show that the modelling technique adopted in this work can more accurately present the phenomena associated with stick-slip process.

A sensorless speed estimation algorithm for use in induction motor fault detection applications

A novel sensorless speed estimation algorithm for use with direct online three-phase induction motors is proposed. Speed information is extracted from the motor current spectrum by tracking the frequency of key components, which vary as a function of motor rotational speed. An important advantage of this technique is that the speed estimation algorithm is independent of motor mechanical and electrical parameters. The algorithm operates via estimating rotor bar number, which is in turn used to determine rotational speed via rotor bar pass frequency detection including a sanity check on estimated speed via comparison with a linear speed estimate based on rated nameplate data. Experimental results are included for a range of three-phase induction motors including motors carrying faults (bearing, rotor, stator and air-gap eccentricity). The results demonstrate the robustness of the algorithm to motors operating with a variety of faults and thus the potential for use of the algorithm in induction motor fault detection and diagnosis applications.