Simulation Research On Hardware-in-the-Loop Test System Of Gasoline Engine Control Unit

The application of electronic control technology has greatly improved the fuel economy and emission performance of the internal combustion engine.The application area of electronic control has developed from the fuel injection control to the electronic management system.Now it has penetrated into every system of the internal combustion engine which can't be separated from it.With the increasing application of new technology,it is becoming more and more complex,and the number and type of sensors and actuators in the system are increasing,which leads to the design of electronic control unit becoming more complicated.In order to ensure the reliability of software and hardware,all parts need to be strictly tested.The design of electronic control unit is a process of developing,testing and improving.When the software and hardware design is completed,the two functions need to be integrated,and the whole control function tested.The controller is installed on the controlled object for test in usual,but the development period of the controlled object is longer than that of the control unit,which results in the controller being unable to be tested and improved immediately.The hardware in the loop test technology can simulates the controlled object operation process by the simulation model and real-time computer hardware.The system can receive the control signals from the ECU and simulate the sensor signals and then transfer them to the ECU which can test the controller instead of the controlled object.For real-time system functions,this paper designs a hardware-in-the-loop test system for gasoline engine control unit.In real-time computer hardware part,according to the controller function and the interface demand,the processor card,I/O card and signal conditioning card of d SPACE are selected and the TDK programmable power device is used as the power supply,and all devices above make up the real-time system.The system can meet the requirements of high real-time performance of engine simulation,complex signal simulation and input and output interfaces.The GUI interface is designed by Control Desk,and the signal correlation is established to the model signals,which can be used to calibrate and measure the parameters of the model.The automatic test cases are established by Automation Desk,and the test results are analyzed on the system.In the aspect of gasoline engine simulation model,based on the functions of each component,a gasoline engine simulation model for controller function testing is established.Firstly,the components and operational principle of the gasoline engine are analyzed.Based on the empirical and theoretical formulas of each module,the simulation models of each module are developed.To enhance the real-time performance of the model simulation,some modules are simulated by linear fitting of experimental data.The model mainly includes fuel supply system model,intake and exhaust system model,in-cylinder combustion model and cooling system model,and each module has build some sub-models according to the components in the system.Secondly,the interfaces of a controller and real-time computer are analyzed.The special interface is used for fuel injection signal,ignition signal and knock signal,and the common interface is used for digital signal,analog signal,PWM signal,etc.And then the relationship between the controller and the real-time computer interface is established respectively.The working principle of each sensor and its function in the control system are analyzed,and the simulation models of various sensors are established,in which the crankshaft,camshaft and knock sensors generate simulation signals based on d SPACE module.The simulation model of temperature,pressure and oxygen sensor is established based on the principle of the sensor and the experimental data and the simulation model signals are output and then displayed by oscilloscope.Finally,the design method of test cases is analyzed,and the related factors are analyzed as well according to the function of each part.It contains the fuel supply system control function,the ignition system control function,the idle speed control function,the air-fuel ratio control function,the load control function,the turbocharging control function,the intake control function,the crankcase forced ventilation control function and the main relay control function.Test cases are designed for each control function and tested one by one in the system.During the test process,the signal data related to each function on the user interface of the host computer are recorded and evaluated.