Guangyu Dong

An Explicit Model Predictive Control Framework for Turbocharged Diesel Engines

The turbocharged diesel engine is a typical multi-input multioutput system with strong couplings, actuator constraints, and fast dynamics. This paper addresses the exhaust emission regulation in turbocharged diesel engines using an explicit model predictive control (EMPC) approach, which allows tracking of the time-varying setpoint values generated by the supervisory level controller while satisfying the actuator constraints. The proposed EMPC framework consists of calibration, engine model identification, controller formulation, and state observer design. The proposed EMPC approach has a low computation requirement and is suitable for implementation in the engine control unit on board. The experimental results on a turbocharged Cat C6.6 diesel engine demonstrate that the EMPC controller significantly improves the tracking performance of the exhaust emission variables in comparison with the decoupled single-input single-output control methods.

Real-Time Energy Management for Diesel Heavy Duty Hybrid Electric Vehicles

In this paper, a fuzzy-tuned equivalent consumption minimization strategy (F-ECMS) is proposed as an intelligent real-time energy management solution for a conceptual diesel engine-equipped heavy duty hybrid electric vehicle (HEV). In the HEV, two electric motors/generators are mounted on the turbocharger shaft and engine shaft, respectively, which can improve fuel efficiency by capturing and storing energy from both regenerative braking and otherwise wasted engine exhaust gas. The heavy duty HEV frequently involved in duty cycles characterized by start-stop events, especially in off-road applications, whose dynamics is analyzed in this paper. The on-line optimization problem is formulated as minimizing a cost function in terms of weighted fuel power and electric power. In the cost function, a cost factor is defined for both improving energy transmission efficiency and maintaining the battery energy balance. To deal with the nonexplicit relationship between HEV fuel economy, battery state of charge (SOC), and control variables, the cost factor is fuzzy tuned using expert knowledge and experience. In relation to the fuel economy, the air-fuel ratio is an important factor. An online search for capable optimal variable geometry turbocharger (VGT) vane opening and exhaust gas recirculation (EGR) valve opening is also necessary. Considering the exhaust emissions regulation in diesel engine control, the boundary values of VGT and EGR actuators are identified by offline design-of-experiment tests. An online rolling method is used to implement the multivariable optimization. The proposed method is validated via simulation under two transient driving cycles, with the fuel economy benefits of 4.43% and 6.44% over the nonhybrid mode, respectively. Compared with the telemetry equivalent consumption minimization strategy, the proposed F-ECMS shows better performance in the sustainability of battery SOC under driving conditions with the rapid dynamics often associated with off-road applications.

Method of ion current detection for HCCI combustion on SI/HCCI dual mode engine

With the advantages of high thermal efficiency and extra low NOx and soot emissions, homogeneous charge compression ignition (HCCI) combustion has become a promising combustion method. Comparing with the SI engine or diesel engine, it is hardly to control combustion phase and combustion period on a HCCI engine directly. Hence, sensing of combustion phase and combustion state is very important for HCCI engine control. In this paper a method of detecting ion current signal as the feedback of combustion characters was discussed through a series of experiments on a gasoline HCCI engine. When the engine operated in pure HCCI mode, the ion current was measured and several parameters were abstracted from ion current waveform in order to investigate the relationship between the ion current and the combustion characters. Simultaneously, the in-cylinder pressure was measured and the rate of heat release was calculated. Experiment results show that there is a strong correction between HCCI combustion phasing and ion current signal. On the other hand, the relationship between ion current and combustion phasing was also discussed when the engine operated under spark assisted HCCI mode. Thus through a set of parameter definition the influence of ignition coil discharge to ion current also be researched.

Thermoelectric exhaust-gas energy recovery: An integrated approach

Here we describe the first results from an interdisciplinary project that seeks to develop a skutterudite-based thermoelectric (TE) energy recovery system for a vehicle exhaust stream. Filled skutterudites have been prepared and characterised and their thermal stability evaluated. Thermoelements fabricated from these skutterudites have been used to evaluate the compatibility of materials required for the construction of TE modules. The results of modelling studies for the optimization of heat exchanger design and the creation of a component in the loop test facility are also described.

Performance Analysis of a Thermoelectric Generator Through Component in the Loop Simulation

As a low maintenance solid state device, the thermo-electric generator (TEG) provides an opportunity to recover energy from the exhaust gas directly. In this paper, dynamic behaviour of a TEG applied to the EGR path of a non-road diesel engine has been analysed. Through the component in the loop (CIL) method, the proposed TEG was simulated by a virtual model in real time. A Nonlinear Auto-regressive exogenous (NLARX) model was operated in an xPC as the virtual model. Based on calculated results of the model, the position of EGR valve and the coolant valve were adjusted to simulate the effect of TEG installation on the gas flow in EGR path. Analysis of the TEG performance under Non-road Transient Cycle (NRTC) was conducted base on above method. With above analysis, following conclusions can be drawn. First, the component in the loop simulation method demonstrates a better performance to predict the TEG dynamic behaviour comparing to the software based methods. Using component in the loop methodology, transient performance of the TEG device can be predicted with a satisfied error range. Besides of the TEG performance prediction, the effect of the installation of the TEG was also analysed. The temperature variation and the pressure drop which affected by TEG system were predicted, and a more accurate TEG performance prediction can be achieved accordingly.