Research On Model-Based Hardware-in-the-Loop Simulation And Control Design In Diesel Engines

With the development and progress of engine technology, the function and the number of the engine electronic control systems have increased much, and the system development also becomes much more complex. Model based design method is a universal applicable design method, its purpose is: the virtual model is used to describe the corresponding physical prototype in the system, and the whole system is simulated in the software or hardware environment so that modifications can be made in time. The cost can be saved and efficiency can be improved when the model based design method is adopted. Based on numerous literatures, this thesis refers and absorbs others' merits, combines the advanced theory and technology of many disciplines, utilizes the model based design method to put out research on hardware-in-the-loop simulation system and control strategy.As an effective auxiliary tool in the process of engine electronic control system development, hardware-in-the-loop simulation system provides a convenient environment for electronic control system development. The core of the hardware-in-the-loop simulation system is engine model, the properly establishment of which is the foundation and key for the fulfillment of the simulation system. Combines physics based first principles and empirical formulations, the mean value model for a diesel engine is established in this thesis, the model includes sub models such as compressor, turbine, intake and exhaust system, and cylinder. An obvious character of the model is its practical use, cycle fluctuation is ignored and the evolution process of the status variables' mean values is intensive described. Engine model development is fulfilled in the MATLAB/Simulink environment. According to the results, a reliable mode, the mean value model owns a high computation accuracy and rapid calculation speed, it reflects and predicts the static and dynamic performance of the engine, provides a good development environment and research object for the development of engine electronic control element.In respect to disadvantages such as tedious process of programming the software, dedicated hardware system is needed, unable to be universal applied, and cannot be extended easily when develop hardware-in-the-loop simulation system previously, this thesis promotes the rapid simulation prototype development system which comprises graphical model development software MATLAB/Simulink and universal applicable PC based Linux RTAI environment. Owns the function of automatic code generation; this system can save the amount of work for programmers, and the rapid computation and I/O capacity of the universal applicable PC can be fully utilized, universal applicable, easily extended and operate, and low development costs are also its merits. Providing a rapid development platform for the development of engine hardware-in-the-loop simulation system and electronic control system with high cost-performance ratio.Building a cycle based common rail fuel system mean value model, promoting a non-linear PID control algorithm which is based on characters of PID control algorithm, conducting research on the closed loop control simulation of common rail pressure in Simulink environment. Simulation results demonstrate that the algorithm is capable of self-adjustment according to system deviation parameters and can speed up system response while reducing system overshoot at the same time.A electronic governor is build for a P-type mechanical fuel pump, in which the linear electromagnet serves as the executor. Design a diesel engine electronic speed control system, the core of which is a 32-bits microprocessor with high performance. A cascade control algorithm was designed. The speed regulation experiment is taken under the hardware-in-loop simulation system.In respect to the non-linear property of engines, modern intelligent control technology and PID are combined to build a CMAC-PID compound controller which is used to do the job of speed adjustment control. According to the simulation results, the combination of CMAC can control better than when PID is used alone, less time is needed for speed becomes stable, overshoot are reduced, system response is also been speed up. Besides, CMAC-PID is less sensitive to PID parameters, namely has a lower requirement for PID parameters.