Research On High Power Braking Energy Control Technology For Marine Electric Propulsion System

The braking process of the ship’s electric propulsion system [1] is very complicated,and huge braking energy will be generated during the entire short-term braking process.If this energy cannot be effectively controlled and processed in time,it will cause a sudden DC bus voltage Increase phenomenon.Once the voltage suddenly rises above the dangerous value,it will seriously damage the related electronic components such as the power switch in the electric propulsion system,and then cause damage to the entire system,which seriously threatens the safety of the operators on board.Therefore,in order to efficiently control the use of this braking energy in a short period of time,it was decided to use a supercapacitor energy storage system combined with a flywheel energy storage system to store and control this part of the high-power braking energy,with a view to eventually Stabilize the DC bus-side voltage within a safe range.The principle of high-power braking energy control of marine electric propulsion system is introduced first.By analyzing and comparing several braking methods of the ship’s electric propulsion system and selecting the best ones,the matching degree and advantages and disadvantages of several energy storage methods to the selected braking method are compared and analyzed.Finally,the combination of super capacitor energy storage and flywheel energy storage is finally determined.Design scheme.The system structure of flywheel energy storage and supercapacitor energy storage is analyzed,and the related working principles are explained.Then,the braking process of the ship’s electric propulsion system is analyzed and studied.A three-phase asynchronous motor is selected to simulate the actual ship’s electric propulsion system.The research on the torque ripple suppression of the permanent magnet brushless DC motor selected for flywheel energy storage is carried out,and the actual energy storage(charge and discharge)process of the energy storage(charge and discharge)of the grid side and the motor side of the flywheel energy storage system is analyzed.Research and design of super capacitor energy storage array and bidirectional DC-DC converter.By researching the related problems of the super capacitor series voltage equalization circuit to further realize the control strategy of the super capacitor system,the feasibility of the effective application of the super capacitor energy storage system in the ship’s electric propulsion system is verified.Finally,the braking process of the propulsion motor of the ship’s electric propulsion system is simulated by selecting the movement of the three-phase asynchronous motor withparameters set under braking and other conditions,and the amount of energy generated by the ship during braking is calculated to determine the flywheel storage.Energy storage capacity of energy systems and super capacitor energy storage systems.On the Matlab / Simulink platform,a simulation platform for the ship’s electric propulsion system is built,and a high-power braking energy control system is constructed.The flywheel energy storage subsystem and the super capacitor energy storage subsystem are designed.During the simulation of the ship’s motion,by giving control signals such as motor acceleration and braking,the simulation verified the high-power braking energy control system for the control of braking energy,the energy storage effect,and the effectiveness of its control strategy.The experimental results prove the feasibility and effectiveness of the scheme.