Combustion Phase Control Of Extended-range Engine Based On Cylinder Pressure Signal

As an intermediate transitional product for pure electric vehicles to completely replace traditional fuel vehicles,extended-range electric vehicles will become the most competitive new energy vehicles in the future market.The extended-range electric vehicle uses an extended-range engine with a smaller battery pack,which not only has the advantages of pure electric vehicles using clean energy,but also solves the problem of pure electric vehicle mileage anxiety.It is worth mentioning that controlling the extended-range engine to work at the best efficiency point,that is,ensuring the highest energy conversion efficiency of the extended-range engine is a difficult point in the research of extended-range vehicles.Through in-depth analysis of the combustion process of the engine,it can be known that the combustion phase of the engine is an important factor that affects the combustion characteristics of the engine such as fuel efficiency,combustion changes and knocking,and it characterizes the entire combustion process.Due to the randomness of the combustion process of the engine,the combustion phase of the engine is uncertain.Therefore,it is challenging to maintain the combustion phase at the optimal reference value under consideration of the transient operation of the engine,the drift of the optimal controllable variable value and the constantly changing physical constraints.Therefore,this design took the BMW F800 GS engine as the research object,built an extended-range engine test bench,designed an engine combustion phase controller based on statistical assumptions,and conducted multiple sets of combustion phase control experiments under various working conditions.And the experimental results are analyzed,which proves the effectiveness of the designed controller,so that the engine combustion phase can be accurately controlled and stabilized at the reference value.First,build an experimental bench for the extended-range engine electronic control system.According to the main structure of the extended-range engine,this paper independently designs the hardware circuit board for engine sensor signal acquisition and actuator drive output,and connects the d SPACE controller with the engine for rapid prototyping.According to the angle information collected by the crankshaft position sensor,Lagrangian interpolation algorithm is used to predict the precise ignition timing.The difference between this design and the general engine electronic control system is that this system installs an in-cylinder pressure sensor in the engine cylinder to synchronize the cylinder pressure signal with the crankshaft angle to quickly calculate the engine’s combustion phase CA50.Second,design an engine combustion phase controller based on statistical assumptions.Considering the randomness and inevitability of the combustion process of the engine,the conventional controller cannot effectively solve the control problem of the combustion phase CA50 of the engine.In this paper,a model of combustion phase CA50 and ignition advance angle is constructed,and an engine combustion phase controller including hypothesis test decisions based on statistical characteristics is designed.The controller has three modules,including a statistical hypothesis testing module,a statistical decision-making module,and an ignition advance angle control module.The statistical hypothesis testing and decision-making module determines whether to activate the ignition advance angle control module by detecting and analyzing the average value and probability distribution of the combustion phase;the ignition advance angle control module is used to correct the ignition advance angle to track the combustion phase to the reference value.Finally,the engine combustion phase control experiment is carried out and the effectiveness of the controller is verified.This paper conducted experiments under two operating conditions,namely steady-state operating conditions and step reference input operating conditions.Analysis of the experimental results shows that although the engine combustion phase CA50 is unstable and has random distribution,its mean steady-state error does not exceed one degree under steady-state conditions;when tracking a small-angle step response,Its mean value tracks the reference value of the step change with a small error.It shows that the combustion phase controller based on statistical assumptions proposed in this paper can meet the control requirements of this range extender test bench,which proves the effectiveness of the controller.