Showing papers in "International Journal of Powertrains in 2016"

State-of-the-art electrified powertrains - hybrid, plug-in, and electric vehicles

Abstract: Automotive electrification has become the centre of current transportation technology especially in the age of surging petroleum fuel prices and rising social awareness of vehicle emissions. A range of electrified powertrains from micro hybrid to full electric have been implemented in a wide variety of vehicle platforms from subcompacts to heavy-duty trucks and buses. The main focus of this paper is to comprehensively review the state-of-the-art electrified powertrains that have been developed and commercialised in the North American automotive industry. Vehicles are categorised based on different powertrain configurations and electrification levels. The powertrain structure and operating modes are also analysed in detail. In addition, a comprehensive database of electrified powertrains and their components is created. Electrified powertrains and the corresponding conventional powertrains are compared in terms of vehicle efficiency, powertrain complexity, and pump-to-wheel CO2 emissions.

Control variable optimisation for an extended range electric vehicle

Abstract: A dynamic programming-based algorithm is used for off-line optimisation of control variables of a series-parallel extended range electric vehicle powertrain. The aim is to minimise the fuel and/or electricity consumption, subject to battery state-of-charge constraints and physical limits of different powertrain variables. The optimised control variables include engine torque and electric machine speed, as well as a variable that selects the powertrain operating mode defining the state of powertrain clutches. The optimisation results are presented for four characteristic certification driving cycles and different vehicle operating regimes including electric driving during charge depleting (CD) regime, hybrid driving during charge sustaining (CS) regime, and combined/blended regime. The emphasis is on the blended regime and a related analysis of fuel saving potential when compared to the CD-CS regime. The optimisation results are used to provide recommendations for design of a realistic (online) control strategy that is a subject of another publication.

Transmission characteristics of injection moulded polymer spur gears: experimental and numerical evaluation

Abstract: The transmission characteristics of gears are the functional requirement when the gears are used for precision motion applications such as robotics, actuators of satellite launchers, etc. In the present study, a test rig has been developed to simulate steel-polymer gear mesh and measured static transmission errors at various roll angles for different loading conditions. Multi tooth gear pair was considered and finite element method was adopted to evaluate static transmission error and gear mesh stiffness at different loads. From the evaluated path of contact, premature and extended contacts were observed due to less stiffness of polymer gear tooth. The results obtained through numerical simulations were compared with experimental results and found to be in good agreement. The difference between polymer and steel gear tooth stiffness, contributes to the non-uniform gear mesh stiffness/static transmission error both at single and double tooth contact regions. The roll angle and static transmission error of gear pair were found to increase with load.

A control oriented multivariable identification procedure for turbocharged diesel engines

Abstract: In this paper, multisine frequency response function identification is used for non-parametric modelling of the air path of a turbocharged diesel engine around a fixed operating point. The variable geometry turbine (VGT) and exhaust gas recirculation (EGR) valve are used as inputs. The nitrogen oxide emissions, air-fuel equivalence ratio, and pressure difference between the intake and exhaust manifold are the considered outputs. A time-efficient and accurate identification procedure for this input-output system is devised, analysed, and executed experimentally for a range of operating points. The analysis quantifies the individual effects of noise and nonlinearities and shows that the identified linear models capture the actual local behaviour with over 97.2% accuracy.

Advanced battery management system design for SOC/SOH estimation for e-bikes applications

Abstract: In this work, state of charge (SOC) and state of health (SOH) estimation algorithms for battery management system are proposed and compared. These algorithms are developed on a battery pack designed specifically for light electric vehicle (electric scooter or bicycles) applications. The advanced battery management system is designed in order to evaluate the instantaneous charge available in the battery and at the same time to monitor the slowly varying battery aging parameters. Two SOC estimation algorithms are proposed: an extended Kalman filter (EKF) and an adaptive extended Kalman filter (AEKF). With the adaptive version of Kalman filter a proper value of the model noise covariance is adaptively set using the information coming from the online innovation analysis. In the second part of this paper, a new estimation algorithm based on least squares is proposed to estimate the battery SOH. A general framework for a combined evaluation of SOC/SOH is discussed.

Multiple pulse laser ignition in GDI lean combustion

Abstract: Laser Ignition (LI) is a new, innovative technology which overcomes several limitations of conventional spark ignition; it presents many potential advantages for engine dynamic control, especially for gasoline direct injection engine. This paper highlights a new approach, using principle component analysis of the pressure curve, to dynamically control multiple pulse laser ignition (MPLI). In the results, experimental data presents how the control of MPLI improves the performance of the engine and demonstrates the effectiveness of MPLI in lean combustion. This work is part of an Engineering and Physical Sciences Research Council funded research project which is to investigate how optimised control strategies, including multiple stratified fuel injection (MSFI); MPLI and multiple location laser ignition (MLLI), can help to improve the stability of leaner operation and reduce the emissions. The possible future of LI dynamical control strategies is discussed.

Durability of injection moulded asymmetric involute polymer spur gears

Abstract: Asymmetric tooth profiles with different pressure angle at drive and coast sides are being considered to enhance the gear performance. In this work, experimental investigations were carried out to evaluate the fatigue and wear performance of injection moulded asymmetric polypropylene spur gears using the power absorption gear test rig. Test gears exhibited wear failure at lower loads and tooth bending failure at higher loads. Periodic measurement of gear tooth thickness and weight loss was carried out to quantify gear tooth wear. Sudden rise in measured gear temperature and failure morphology confirmed bending failure at higher loads. The results revealed that asymmetric gears exhibited inferior performance than that of symmetric gears. This behaviour is due to the reduced contact ratio, increased normal load and increased height at which worst load act on the gear tooth profile for the considered test conditions.

Correlation of light-off activity for full size and cored catalyst samples

Abstract: This study identifies, and analyses, the correlation that exists in the CO light-off performance of full size canned catalytic converters and cored samples taken from the front and rear sections of the same catalyst brick Testing was conducted under laboratory conditions, with full size samples tested using the Catagen Labcat, and testing of cored samples conducted using the Horiba SIGU 2000 From experimental tests alone, there was no clear correlation between the CO light-off activities of full size and cored catalyst samples However, by performing simulations using the QUB global catalyst model, which accounts for the variation of precious metal dispersion and differences in the heat transfer characteristics of the test rigs, correlation was shown to be good

Ultracapacitor power assist with preview-based energy management for reducing fuel consumption of heavy vehicles

Abstract: This paper investigates the potential improvement in fuel economy of a heavy transport vehicle with the power assist provided by an electric motor and a high power density ultracapacitor energy storage system in a parallel hybrid configuration. With full and a-priori knowledge of the future driving cycle, the optimal control technique of dynamic programming (DP) calculates the 'best possible' fuel economy. Attainable fuel economy improvements, in absence of preview knowledge, are illustrated using a simple model for predicting future torque demands and via receding horizon optimisation. Furthermore, the role of telematic information in managing the limited energy buffer of ultracapacitor storage is evaluated. Further increase in fuel economy, toward the DP-calculated maximum, are shown with the incorporation of simulated telematic preview information.

Application of linearised hierarchical models to indicated torque modelling for a turbocharged engine

Abstract: This paper shows the application of linearised hierarchical models to the estimation of indicated torque data obtained from a large scale engine mapping experiment conducted on a turbocharged spark-ignition engine. Unlike previous studies that have utilised two-stage regression techniques for analysis, the use of linearised methods provides a framework to directly address the issues of sparseness of sweep-specific data and mixed effects modelling. In addition, spline models are presented at both levels of the model hierarchy that possess the required smoothness, are capable of capturing physical behaviour and simultaneously yield models sufficiently accurate for calibration work. The paper considers, at length, the required model fitting procedures which are founded on an iterative generalised least-squares approach. Further, a model building case study is presented addressing the issue of which factors should be modelled as fixed or mixed. This utilises information criteria to identify the most parsimonious model. Finally, the fit provided by the model to the data is demonstrated, which is seen to satisfy the engineering measure of success applicable to the application.

Model-based optimisation and predictive control of a turbocharged diesel engine with variable geometry compressor

Abstract: This paper presents a model-based optimisation and preliminary control design for a diesel engine equipped with variable geometry turbocharger (VGT), exhaust gas recirculation (EGR), and variable geometry compressor (VGC) systems. Starting from a validated model of the engine air path dynamics, a model-based optimisation is conducted at steady state conditions. The optimisation results define a simple feed-forward control strategy, which shows how the VGC can be used to increase the stability range of the compressor by means of shifting the surge limit of the machine while providing opportunity to improve fuel efficiency and turbo-lag. A design of feedback control is then investigated by coordinating the available actuators to track the desired performance variables derived from the steady state optimisation, and ensure the stability of the compressor during transient. The regulation is formulated as a receding horizon optimisation problem, which is cast as a constrained quadratic programming to reduce the computational load. The proposed controller is implemented into the nonlinear engine model, followed by an analysis of the simulation results.

Simulation and experimental study on ion current under GDI-HCCI combustion mode

Abstract: For a gasoline HCCI engine, the major challenge comes from the ignition and combustion control. Therefore, a feedback signal is necessary to detect combustion state and to realise closed-loop control of combustion process, and ionisation technology was studied for the purpose. The simulation results indicated that the 3D-CFD model could accurately predict in-cylinder pressure, heat release rate, ion profile, ion distribution and its generation mechanism. The experimental results showed that the fuel injection rate in NVO was of more significance to the HCCI combustion phase and the ion current, and HCCI combustion phase can be controlled by the fuel transmutation. In the wake of the excess air coefficient reducing, the amplitudes of the cylinder pressure and ion current were increased, and the phases were advanced. Under high load condition, the reduction of the throttle percentage caused increase in the fluctuation of the IMEP coefficient but weakness in the middle load.

A control-oriented NOx emissions model for diesel engines

Abstract: A control-oriented, low computational cost nitrogen oxides emissions model for a diesel engine is presented. The model is based on zero-dimensional one-zone nitric oxide formation thermodynamics. The main inputs to the model are measured cylinder pressure, engine speed and manifold air flow rate. As only three model parameters are required, the calibration effort is minor. Instead of solving nonlinear equations to obtain the oxygen concentration from dissociation reactions, a simple estimation method used the estimated number of moles in the burned zone. The model was validated using engine data and show that the model can predict emissions with high accuracy as they vary with load, start of injection, fuel rail pressure and exhaust gas recirculation rate. As there are few, relatively simple algorithms involved, this model can easily be implemented online. It also has potential to be used in the control of both exhaust after-treatment and the engine combustion process.

Influence of addendum modification on spur gears stability

Abstract: The aim of the presented research is to develop the new method for studying the influence of main characteristics of spur gears on their stability behaviour. Few different processes and calculations are compiled in algorithm make a method for spur gears stability analysis. In this paper, the main influence factors for spur gears stability are identified and the discussion of appropriate dynamic model of spur gears is given. In order to determine the time-dependent load distribution and mesh stiffness, developed procedure uses verified spur gears model for finite element analysis. The special attention has been devoted to the research and conclusions about the influence of addendum modification on spur gears low-vibration and stability. The discussion is based on comparative study of a series of gear pairs with different addendum modification coefficient in order to select the optimal tooth profile design with gear pair low-vibration and stability as the main aspects.