Research On Control Technology And Energy Feedback Process Of Electric Cargo Ship Propulsion System

With the development of new energy technology,the promotion of pure electric ship will become one of the development directions of inland and coastal small ships in the future.Pure electric ship has the advantages of high maneuverability,good safety factor and high intelligence.However,there are still many problems to be studied in practical application.This paper mainly uses Matlab / Simulink software to model,simulate and experiment the motor control system and propeller load system of pure electric propulsion cargo ship,in order to improve the performance and economy of pure electric propulsion system.The main contents and conclusions are as follows:The vector control system of permanent magnet synchronous motor is modeled and simulated based on MATLAB / Simulink software.The current loop and speed loop of cascade PI control are analyzed in frequency domain from inside to outside.Combined with Bode diagram,a practical controller parameter setting scheme in engineering is discussed.Finally,the variable load condition and on load speed regulation are simulated.In order to improve the dynamic performance of permanent magnet synchronous motor vector control system under variable load torque,a lomberg load torque observer is designed.Through the test,it is found that the observer can track the unknown load torque signal quickly,stably and accurately.According to the observed load torque value,the feedforward compensation is carried out for the q-axis current loop.The feedforward feedback composite control method is compared with the PI feedback control alone.The test is carried out under the condition of increasing and decreasing load.It is found that the composite control scheme can effectively reduce the speed fluctuation under the condition of load torque disturbance,and the dynamic response performance of the current loop(electromagnetic torque)is better.The basic characteristics of ship engine propeller and ship kinematics model are modeled.In Matlab / Simulink software,the system is simulated and analyzed by giving the propeller speed curve to verify the correctness of the model.The four quadrant working characteristics of motor and propeller and the principle of energy consumption braking are analyzed.Then,combined with typical ship operating conditions,the processes of graded forward starting,parking free deceleration and reverse braking are simulated and analyzed respectively.There is energy feedback in the process of parking free deceleration and reverse braking.Based on the ship operating conditions,the design of energy storage system is discussed,and the configuration of energy storage unit is refined into a typical multi-objective optimization problem.Finally,this problem is described and analyzed in combination with the typical operating conditions.