Energy Storage and management
2005-20061) Project Title: Modeling and design of peak power buffer system using flywheel-motor/generator and ultracapacitor
Objectives: A flywheel energy storage system built in a permanent magnet motor/generator has been shown to be capable of providing power to intense pulsed loads. Compared to electrochemical batteries, a flywheel system has long life, small volume and weight, and high power density. This storage system is good for meeting pulsed loads on a time scale from milliseconds to seconds. On the other hand, an ultracapacitor can supply a rapidly changing dynamic load because it allows fast discharging and charging. Under battling conditions, high-magnitude bursts of power need to be delivered to weapons in a time scale of microseconds.
Thus, a flywheel-ultracapacitor bank combination is desirable. Such a hybrid power source is a complex electromechanical system coupled with power electronic converters and ultracapacitors. The design involves hundreds of variables. A complete dynamic system investigation of such a system is necessary to obtain a high-fidelity simulation model suitable for design. This model, implemented in VTB, will aid the optimal design of the hybrid energy system. To minimize weight, volume, and loss of the overall energy storage system, optimal energy and power distribution between the flywheel and ultracapacitor will be determined based on a realistic model of ship pulsed power loads. This, in turn, will affect the optimum control of the system. Also, the stability issue of the flywheel system supplying high pulsed load will be investigated. The results of this project could be extended to the energy storage design of EMALS (Electromagnetic Aircraft Launch System).2) Project Title: Investigation of the effects of current ripples on fuel cell system performance for e-ship distributed power generation
Investigator: David Gao
Objective: To investigate the effects of current ripples generated from interfacing power electronic circuits on fuel cell system performance by simulation and experiment for fuel cells used onboard electric ship distributed power generation where pulsed loads in service may aggravate the problem.
2006-20071) Project Title: Fuel Cell Distributed Generation and Storage Implications for Ship Systems
Investigators: Herb Ginn, David Gao (Tennessee Tech)
Objectives: The important priority for electric warships is to maintain power continuity to the mission-critical loads. Since most of these critical loads are inherently pulsed type, increasing the ratings of prime mover and main generation is not a good option. Distributed generation (DG) can quickly and efficiently meet the load demands locally. Micro-turbine and fuel cells are two possible options. On one hand, we need to develop an interfacing strategy to integrate the power generated by fuel cells to the ship power system. On the other hand, a fuel cell’s output power cannot be changed abruptly, dictating that other types of energy storages are needed. This project will be broken into two parts. Part 1 will focus on the integration of fuel cells within a ship DC Zonal Distribution System.
In the future all electric ship, more pulsed loads, such as electromagnetic rail gun, Electro-Mechanical Aircraft Launch System (EMALS) and new high-energy weapon systems, are anticipated. Energy storage systems and DG sources can ensure reliable power supply to mission-critical loads while increasing system stability margin.