Model-based Diesel Engine Speed Control System For Water-jet Propulsion

The diesel engine is commonly used in water-jet propulsion ships,Modeling of the diesel engine is apparently beneficial for designing more precise diesel rotation speed control system.In this paper,the structure of the rotation speed control system for the diesel engine equipped in a water-jet propulsion speed boat is investigated.Two generalized diesel engine model,the piecewise low order model and the first order affine nonlinear model,are established by taking the diesel injection manipulating signal as the input and the engine rotation speed as the output the output.The open-loop step response curves of the diesel engine at different speeds are obtained.The parameters of piecewise low order model are identified by using the data from the open loop experiment.The comparison between the identification results and the measured data indicate the goodness of fit of the generalized diesel engine plant is over 95%.It is demonstrated that the piecewise low order model proposed is able to describe the plant both in steady state and in transients.The disadvantage of piecewise low order model is undisturbed switching must be considered in different work conditions.On the other hand,the first order affine diesel engine model is studied.Feedback linearization method is selected to linearize the nonlinear model globally in application stage.The simulation is carried out in Simulink platform to contrast the control quality and capacity of resisting disturbance between mechanical governor,normal PID based on mechanical governor,feedback linearization PID based on mechanical governor and feedback linearization slide model controller based on mechanical governor.The simulation results indicate that feedback linearization slide model controller based on mechanical governor has the best control quality and anti-disturbance ability.