Research On Modeling And Simulation Of Marine Electric Propulsion System

With the development of ship propulsion technology and the continuous improvement of modern control theory,there have been new changes in the field of modern ship propulsion.Facing the increasingly complicated marine environment and increasingly serious environmental problems,in order to improve the fuel economy of marine propulsion motors,reduce pollution emissions,and enhance the stability of marine electric propulsion systems,advanced control theory needs to be applied to the field of marine propulsion.China has a low starting point and a late start in the field of ship electric propulsion technology.In order to reduce unnecessary waste of resources,it is necessary to perform modeling and simulation analysis of ship electric propulsion systems in advance.This subject takes a typical ship electric propulsion system as a research object,and modularizes the electric propulsion system into a ship electric system,a ship motion control system,and an electric propulsion control system,and models and simulates them.The research focuses on the control strategy of permanent magnet synchronous motors based on fractional sliding mode control.The following research work has been completed:First of all,the mathematical models of diesel engines and speed regulation systems,generators and excitation systems are established,and simulation models of diesel generator sets are established,which are combined with static load models to form ship power system models.The system was subjected to sudden addition and unloading simulation tests to verify that the designed diesel generator set system can meet the requirements of the specification and is correct.Secondly,after a comparative analysis of vector control and direct torque control,after comparative analysis of vector control and direct torque control,a spatial phasor model of permanent magnet synchronous motor is established on the basis of coordinate transformation,and the principle of vector control of rotor flux linkage orientation is mainly introduced.Combined with the SVPWM modulation technology of _di=0,a servo control system based on three closed-loop permanent magnet synchronous motors with current,voltage and position is designed.Then use the exponential approach law to design and simulate the speed controller of PMSM vector control system,and then introduce the fractional-order theory into sliding mode control to reduce the chattering phenomenon.Secondly,the control performance of the fractional-order approach law is verified and analyzed.,And finally applied it in PMSM servo control system.In order to improve the anti-disturbance capability of the load and the accuracy of the rotor position control,a fractional-order integral sliding mode surface and an adaptive law with threshold parameters are used to design a fractional-order sliding-mode speed controller and fractional-order adaptive with load torque observations.Sliding mode position tracking controller surface.Finally,it is compared and verified with traditional sliding mode and adaptive sliding mode.At last,a detailed analysis of the open water characteristic curve of the propeller,and established a ship-propeller system simulation model,and the relevant simulation research on the propeller start-up mode was focused.Finally,a complete ship electric propulsion system was built,and the stability of the system was studied under large disturbances.