Byron Mason

Reconfigurable modelling for drivetrain real-time simulation

Abstract This article discusses a body of ongoing work that seeks to reduce the time and effort required to create, reconfigure, and parameterize physically based models that are to be used as part of a model-based design (‘MBD’) process. Initially a new modular approach for system model creation is presented. The method facilitates rapid creation of simulation models to be used within an MBD process making use of application-specific submodels. It is shown that through the use of the submodels created using Simulink configurable subsystems, the number of degrees of freedom and thus fidelity of a model may be altered by a simple parameter change. The work continues, beyond the introduction of a number of plug-and-simulate drivetrain submodels, to investigate a means by which a models parameters may be reduced to an absolute minimum. An algorithm capable of identifying parameters of potentially low significance to an output of interest is shown in the form of the parameter elimination and model evaluation algorithm (‘PEMEA’). Simulation results that make use of the PEMEA suggest that a number of parameters may be eliminated. The parameter eliminations, conducted in situ in Simulink models, are shown to have minimum effect on the model outputs-of-interest and marginally decrease the computational overhead of the model.

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.

Optimal selection of an electric drive system for a series hybrid vehicle using analytic hierarchy process

Hybrid electric vehicles (HEVs) are built using advanced technology to reduce exhaust emissions and increase fuel economy, which are the main objectives of the automotive industry today. Motors/controllers are the most fundamental components, especially in a series configuration, to produce and control the drive force for the hybrid vehicles. This paper presents a method of selecting the optimal drive motor/controller for a series hybrid vehicles, based on the requirements. This paper provides an overview of electric drive motors/controllers and analytic hierarchy process. ADVISOR is utilised to simulate the hybrid vehicle performance, employing different categories of AC motors/controllers in the powertrain. The analytic hierarchy process is then implemented with consideration given to several performance criteria for the comparable motors/controllers of the series hybrid vehicle. Results show a typical permanent magnet motor/controller has a better performance compared to induction motors/controllers.

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

An Integrated Framework on Characterization, Control, and Testing of an Electrical Turbocharger Assist

Electrical turbocharger assist is one of the most critical technologies in improving fuel efficiency of conventional powertrain vehicles. However, strong challenges lie in high efficient operations of the device due to its complexity. In this paper, an integrated framework on characterization, control, and testing of the electrical turbocharger assist is proposed. Starting from a physical characterization of the engine, the controllability and the impact of the electrical turbocharger assist on fuel economy and exhaust emissions are both analyzed. A multivariable robust controller is designed to regulate the dynamics of the electrified turbocharged engine in a systematic approach. To minimize the fuel consumption in real time, a supervisory level controller is designed to update the setpoints of key controlled variables in an optimal way. Furthermore, a cutting-edge experimental platform based on a heavy-duty diesel engine is built. The proposed framework has been evaluated in simulations, physical simulations, and experiments. Results are presented for the developed system and the proposed framework that demonstrate excellent tracking performance, high robustness, and the potential for improvements in fuel efficiency.

Simulating the influence of injection timing, premixed ratio, and inlet temperature on natural gas/diesel dual–fuel HCCI combustion in a diesel engine

Dual–fuel HCCI engines allow a relatively small quantity of diesel fuel to be used to ignite a variety of fuels such as natural gas or methane in HCCI mode. The gaseous fuel is mixed with the incoming air, and diesel fuel is sprayed into the cylinder by direct injection. Mathematical modelling is used to investigate the effects of parameters such as premixed ratio (fuel ratio) and pilot fuel injection timing on combustion of a dual–fuel HCCI engines. A CFD package is used with AVL FIRE software to simulate dual–fuel HCCI combustion in detail. The results establish a suitable range of premixed ratio and liquid fuel injection timing for low levels of NOx, CO and HC emissions along with a reliable and efficient combustion. Dual–fuel HCCI mode can increase NOx emission with lower premixed ratios in comparison to normal HCCI engines, but it is shown that the NOx emission reduces above a certain level of the premixed ratio. Due to the requirement of homogenous mixing of liquid fuel with air, the liquid fuel injection is earlier than for diesel engines. It is shown that, with careful control of parameters, dual–fuel HCCI engines have lower emissions in comparison with conventional engines.

A Model-Based Approach for Determining Data Quality Metrics in Combustion Pressure Measurement

Measuring and monitoring the cylinder pressure in relation to the instantaneous cylinder volume allows the engineer to gain a great deal of information about the quality and efficiency of the energy conversion process taking place inside the cylinder. Many useful metrics can be derived or extracted from the pressure curve and these parameters are well established. This article forms the basis to propose a set of basic combustion data metrics that can be used to establish the quality of measured data. The proposed indicators can be used to establish fitness for purpose of the proposed system set-up for various measurement applications, prior to undertaking the critical measurement task. In addition, these metrics can be used or monitored during system run time, to ensure consistent data quality throughout short- or long-term test procedures, in addition to allowing identification of measurement drift or step change factors that could affect data quality over time. This article shows the application of DoE-based testing and a model-based approach in order to establish the response of newly developed metrics when stimulated with target error variations. The output could be used to understand the variation and interactions of the newly developed metrics, and also to understand if they would be usable for the application suggested. It was found that not all of the results that were tested could be utilized, but the test and measurement environment, plus the unique application of model-based testing, facilitated an efficient working environment to support future development work.

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.

Rotary Compact Power Pack for Series Hybrid Electric Vehicle

This paper presents a new–designed compact power pack for a series hybrid vehicle. A new type of rotary induction machine with an outer rotor construction is designed to be coupled with the novel rotary internal combustion engine (ICE) with cylindrical crankcase in order to form the compact power unit. The starting and generation performance of the designed machine as well as the overall vehicle performance is analysed. Results show that the proposed power pack has the best performance in terms of fuel economy, emissions and battery charging compared to the existing power units in ADVISOR. Over a city cycle, fuel economy is increased by up to 47% with emissions reduced by up to 36% and over the highway cycle, fuel economy is increased by up to 69% with emissions reduced by up to 42%.

Hydraulic axis actuation control for precision motion

A new design for machine tool axis traverse, by hydraulic cylinder with spool and needle valve actuators, is presented. Regulation procedures enabling the formulation of a least effort control strategy are proposed. System integrity in the event of actuator failure is examined. Correspondingly, the maintenance of closed-loop stability, following feedback transducer loss, is also secured, demonstrating fail-safe, multivariable and feedback control. The suppression of the effects of disturbances and the response of the system to deterministic inputs is presented. Comments on the practicality of the design are incorporated and the mandatory specification of control system integrity is advocated.