The revolution, that is model based system engineering, continues to take hold in the area of shipboard systems. The concept of an All-Electric Ship (AES) has expanded since 2000 when the US Navy selected electric-drive propulsion for use in the DDG-1000 destroyer. The AES concept offers a range of benefits for the Navy-of-the-future but it also includes a wide array of technical challenges best solved using model based techniques.
In an AES architecture, systems found in traditional ship designs, based on steam, hydraulic, and pneumatic power, are replaced with electric systems. Electric power is supplied to the ship with traditional onboard power generation such as gas turbine engine, diesel engine, or nuclear power and is fed into the shipboard power grid. Key benefits of the AES approach are numerous, including better fuel efficiency, ability to support power requirements of advanced weapons and communications systems, reduced ship lifecycle costs, increased stealthiness, and improved survivability.
Of the power generated in the All-Electric Ship, approximately 70% to 90% in an Integrated Power System (IPS) is used by the ship propulsion systems. During mission critical or life critical situations the interactions between shipboard systems sharing power represents a significant challenge. The management of power demand and the ability to actively reduce power demand for less critical systems, during a wide array of scenarios, must be accounted for. Furthermore, the overall design of this highly complex, tightly coupled integrated shipboard power architecture poses a challenging set of problems, particularly when the overall goal is to design an optimally efficient architecture.
Real-time simulation based development, integration, and verification facilities, as well as model based rapid controller deployment systems, are tremendously important tools to help solve these shipboard system engineering challenges.
Shipboard systems are designed, characterized, and optimized using desktop simulation. Next, each system is combined with some amount of “real” equipment and some amount of simulation to develop and integrate a wider scope of capability. Eventually, all the individual systems (or as many as possible) are brought together in a real-time simulation based integration facility and connected to simulated behavior of the ship’s normal operating and failure mode conditions to thoroughly investigate and understand the interactions between power electronics, machines, and sea conditions. The ADvantage Framework provides the software platform that layers on top of commercial-off-the-shelf computer equipment to create the simulation testing backbone for shipboard systems development. The ADvantage Framework includes the tremendous depth of capabilities required to handle the large, many-system, distributed architecture of a shipboard systems integration facility and to include the large computational capability required to accurately simulate the unpredictable and complex behavior of sea conditions interfaced with stochastic time-varying propulsion loads.
Integrated Power System
The IPS, known in the commercial marine industry as Integrated Electric Drive (IED) and renamed in military applications for obvious reasons, offers a highly efficient, electric-side integrated power and propulsion system by combining advanced solid state power electronics, multi-Megawatt motor drives, and automated controls. The ADvantage Framework is designed to meet the high-performance requirements associated with the development of IPS subsystems and the integration of each subsystem into the complete, optimized IPS. Technologies such as hyperfast, multi-core real-time task allocation and FPGA based simulation and control integral to ADvantage and critical to IPS development.
FPGA based Simulation, Data Acquisition, and Control
The implementation of advanced power generation, conversion, and motor control has become increasingly dependent on FPGA integrated circuits with purposed-designed HDL code to provide a maximum-frequency, maximum-efficiency solution. FPGAs are used as sub-microsecond-frametime HIL simulation processors as well as central processing units for the control of a given subsystem (ex: power converter control, power generation control, motor control). The ADvantage Framework supports commercial-off-the-shelf FPGA computer boards within a small hardware-in-the-loop simulation and prototyping system and within large, multi-node, distributed hardware-in-the-loop simulation and prototyping facilities with unmatched performance.