Research On Model-based Calibration Of GDI Engine

In the development of the automotive industry, energy and environmental issues arevery prominent, so energy conservation and emission reduction has been the main goal ofthe new engine technologies. Of all the technologies, the development and application ofelectronic control technology and gasoline direct injection technology is more prominent.The good implementation of the electronic control system functions depends largely onquality of calibration and matching, accurate and reasonable control parameters are essentialfor engines. With more powerful functions, more and more parameters have complexinfluence on each other, today’s electronic control system has been more difficult tocalibrate. GDI engine has different modes of operation and different control strategies indifferent conditions, which puts forward higher requirements for calibration. With lowefficiency and high cost, traditional calibration methods have been difficult to adapt to therapid development of the engine. Model-based calibration technique is a good choicebecause it can significantly reduce calibration workload, shorten the calibration cycle, andreduce the cost of calibration.In this paper, the model-based calibration technique was used in GDI engine andfollowing work had been done:（1）Built the engine test bench to provide a platform to explore the engine operatingrange and model validation;（2）Determined the engine calibration model, input factors, output response and therange of the input factors, completed the experimental design of the GDI engine usingSpace-filling method;（3）Established engine one-dimensional simulation model by Boost, collected testdata and sort out the data;（4）Established engine torque, exhaust gas temperature, maximum cylinder firingpressure second-order response model by quadratic polynomial and radial basis function;（5）Combined local optimization and global optimization to complete optimization using Sequential Quadratic Programming and generated the engine ignition advance Mapand intake cam phase angle Map.The study found that a partition working area experimental design is needed for GDIengine because the control strategy and the air-fuel ratio range of homogeneous mode andlean-burn mode is different, and Space-filling method with Sobol Sequence is the bestchoice for such programs; model type selection is critical in data modeling, accuracy of asimple model may be not enough, complex models may lead to overmatching, piecewisequadratic polynomial local model of the engine torque has higher accuracy, but themaximum cylinder firing pressure local model has to select the ordinary quadraticpolynomial, which mainly depends on the shape of the response curve, global model ofradial basis function discrete model is very appropriate; data acquisition by enginesimulation model can further reduce the bench test and calibration costs, but modelaccuracy and computational speed is the main problem. Model-based calibration techniquecan be applied to GDI engine with its own characteristics very well, the generated optimalMaps are reliable, and it is a promising calibration method.