Research On The Storage Method Of Braking Energy Recovery In Marine Electric Propulsion System

In the ship electric propulsion system, the boat may generate huge braking energy when it brakes quickly, after the part of the energy goes back to the DC side through the inverter, it wi]] cause DC voltage rising rapidly. It directly endangers the normal operation of other devices, even to be a threat to crews safety. Recently, the method of braking resistance absorption is always used to resolve tremendous feedback energy generated when ships brakes. It is released into the air in the form of thermal energy. Obviously, this method will waste resources and destroy the environment. If the part of the energy can be recovered, it is bound to create a huge economic benefits. Therefore, the research on the storage method of braking energy recovery in the marine electric propulsion system is necessary. In this paper,the braking energy recovery is storaged by the method of super capacitor energy storage.First, by reading reference literatures, the features of braking energy recovery in the marine electric propulsion system is gave out in this article, and acknowledged the current development status of various storage technologies and features. After a comprehensive comparison, the method of super capacitor energy storage is determined to be adopted. In the paper, the super capacitor energy storage mechanism and equivalent numerical simulation model are introduced, and monomer selection basis and testing on the properties are given. It also Shows the necessity of super-capacitor bank in series voltage balancing?Secondly, on the basis of understanding the braking modes of the frequency control system of motor in the marine electric propulsion system, feedback energy is dealed by the way of renewable energy storage. Mainly, the DC-DC converter design and control were studied in detail. The paper proposed matching design method for limited energy storage from the perspective of energy restriction, and designed ultra capacitors bank. Taking three-phase asynchronous motor for example, made a simulation for ships braking process by using the Matlab/simulink, the result shows that it can achieve the goals about braking energy recovery in the process of motor braking.Finally, a new voltage balancing circuit is proposed in this paper, which is a double switch single transformer based on half-bridge inverter and voltage multiplier voltage balancer for super capacitor voltage imbalance problem. The balancer does not require voltage detecting unit,less switch quantity required, reducing magnetic components and without feedback control.Building a simulation model in the MATLAB/simulink, verify the pressure equalizer equalizing effect. Results show that the theoretical analysis and simulation results are consistent, the balancer to achieve the desired effect, and combining with the braking energy storage system for simulation analysis.