Hybrid locomotive have more than one power source to provide driving power. The prime power source of a hybrid locomotive can be a diesel engine or fuel cell, and the on-board energy storage system can provide a secondary power. The rechargeable energy storage system (RESS) of hybrid locomotives can temporarily store energy which is captured from braking action or redundant energy produced by the diesel engine to reduce fuel consumption and pollution.
The Electro-mechanical Battery (EMB) which is a energy storage system for hybrid locomotives, consisting of the accumulator, pump/motor, reservoir and an electric motor/generator is introduced in this thesis. The hydraulic energy storage system has the advantages of high power density and low cost compared to the other vehicle‟s energy storage systems and has the potential to be an energy storage system for hybrid locomotives.
Simulation of the EMB system is implemented to verify its capability of providing burst power for short period during charging and discharging. Based on themathematical analysis of the EMB, the control system is designed to control the hydraulic pump/motor of the EMB to discharge and charge with the required power. The control response frequency of control system which determines how fast the system responds could be between 1 Hz and 3 Hz. A lower frequency of the control system results in smoother operational results of the EMB.
The simulation results obtained by MATLAB/SIMULINK model and Simscape/SimHydraulic model are compared to make the conclusion. Based on the simulation results, four independent and changeable parameters within the EMB system were analyzed to further understand this designed energy storage system.