Research On Marine Electric Propulsion System Based On Multiphase Asynchronous Motor

Electric power propulsion is being widely applied and studied as the new generation of ship propulsion.With the increasing cooperation of global energy,politics and economy,electric propulsion ships show outstanding advantages and characteristics in the field of offshore operations such as freight transportation,scientific research,engineering and security.It has high operational flexibility,fast system response,sufficient power and energy saving.In this paper,the multi-phase asynchronous motor is used as the propulsion motor to complete the research and optimization of the modeling,simulation and control algorithm of the electric propulsion system,which includs the pre-stage five-phase five-level inverter and the rear-stage double propeller load.At last the hardware test and control method verification in the power supply side are completed.The traditional five-phase two-level inverter is modeled and the voltage and current decoupling control algorithm with filtering is studied and simulated.On this basis,according to the research application background,the inverter topology is optimized.A five-phase five-level H-bridge inverter is built with the use of the SVPWM modulation strategy to provide higher quality electric energy for the propulsion motor.The five-phase asynchronous motor is used to replace the traditional three-phase motor as the propulsion motor of the electric propulsion ship,with its model construction and mechanism analysis in both the natural coordinate system and the rotating coordinate system.Then,the characteristic analysis of the propeller and motor is carried out.The parameters are selected and the Chebyshev curve is fitted to complete the typical working condition simulation and characteristic analysis of the single propeller model.Due to few researches and simulation studies on the characteristics of the double propeller propulsion model,this paper re-models the double propeller propulsion model,and analyzes the interaction between the double propellers and the ship according to the fluid dynamics.The parameters calculation of the double-propeller ship such as the wake factor and the speed coefficient are carried out to complete the simulation research and comparative analysis.According to the vector control idea,the state equation construction and control principle analysis of the five-phase asynchronous motor in rotating orthogonal coordinate system are completed.Then the double closed-loop controllers are designed.Simulations of the steady-state condition and the load changing dynamic condition are finished.Besides,the predictive control idea is applied,and the model predictive control based on the deadbeat algorithm is used to control the five-phase asynchronous motor.After that,an optimized algorithm based on the state variable increment in the rolling time domain is designed.According to the working mechanism of the motor,the prediction model is built,taking the current as the control variable.The unconstrained optimal solution of the optimized control quantity is calculated in the extended time domain,and the system simulation is completed and compared with the vector control result.In order to do the the five-phase AC power output test,the inverter hardware is built in the laboratory environment.It includes designs and device selections of sampling,driving and filtering circuits.Then the STM32 controller is used to write the algorithm program after completing parameters calculation of each part.At last the five-phase AC output function is tested and the control algorithm is proved to be correct.