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The recently commissioned Iwo Jima (LHD 7) is the last ship with conventional steam propulsion that the U.S. Navy plans to build. The LHD 8 is the next ship of the class and will be built as a modified repeat design of the LHD 7. The key modifications are steam propulsion being
replaced with a hybrid propulsion system of main gas turbine engines au...
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Citations
... The AHDS system offers several benefits over classical thermal-based combined propulsion systems, including efficient gas turbine operation at low ship speeds, additional power for sensor and weapons systems, and an efficient power dispatch for the main ship generators. The AHDS has been proposed as a new configuration for naval platforms, such as the U.S. Navy's Landing Helicopter Dock 8 amphibious assault ships [17], [18]. ...
Electrically propelled ships gained popularity by the early 20th century, with the rapid development of submarines and medium capacity container ships, mainly using dc motors. Synchronous ac motors have since been employed for naval propulsion systems, but due to the restricted operation of the available power electronic devices at that time, these configurations were too expensive and unreliable, and they featured poor performance in terms of speed and torque control. Improvements in power electronics devices and drive control schemes as well as the development of high-efficiency multiphase induction and synchronous motors have pushed the advancement of electric ship propulsion systems and applications.
... This approach was used on LHD 8 and subsequent LHA 6 class ships. (Dalton, et al. 2002) The "AND" hybrid drive can reduce the required power from the mechanical drive prime movers and increasing the required capacity of the electric plant. Designing a propulsion motor and its associated drive to be able to efficiently provide its maximum power over a wide speed range is more complex than designing a propulsion motor in the "OR" configuration. ...
This paper explores the impact of ship requirements on the selection of a preferred electrical distribution system and propulsion system on a modern surface combatant. Four different plant architectures are considered: Mechanical Drive, Integrated Power Systems, Hybrid Electric Drive, and Hybrid Electric Drive with Propulsion Derived Ship Service (PDSS) electrical power. Requirements such as sustained speed, endurance, survivability, flexibility including margins and service life allowances, electric load conditions, definition of mission critical equipment, and signatures are discussed. The impacts of these requirements on the four plant architectures are presented. The
end goal is to highlight those important requirements that should be investigated and
established early (or accommodated via flexibility) to enable a faster maturation of the
electric plant and propulsion plant design.
... Following this motivation, in the present work a selective control scheme is being proposed, within a marine diesel engine propulsion system, with a direct driving shaft generator and a back to back converter, to enable the diesel engine prime mover to operate on its minimum emissions operating point (MEOP). To accomplish with the previous requirement, the electric drive is forced to operate as a power take-off, using the electric drive as a shaft generator when the prime mover is on its low load region, or as a power take-in, with the electric drive providing power to complement the mechanical drive, when operating on the diesel engine's high load region [7], [8]. ...
... The proposed drive would meet MIL-STD-1399-300 electrical power quality requirements. Dalton et al. (2002) reported that the VSD drive alleviated the need to have 3 paralleled generators to provide inrush current if a soft start capability (provided by the VSD) were not provided. The VSD enabled either a single dedicated generator to power the power, or for two paralleled generators to simultaneously power the motor and serve ship service loads while meeting power quality requirements. ...
Transitioning technology from the academic and industrial research environment to installation on USN ships is a complex process that intersects five domains: The S&T Community, the Resource Sponsors, the Acquisition and Engineering Community, Industry, and the Fleet. This paper presents both the current model and an alternate model for technology transition. These models reflect three drivers for inserting a new technology into a given system: filling a military capability gap, exploiting technology opportunities, and managing risk across a portfolio of systems. A discussion of how the different domains impact the processes is also included. The paper continues with a discussion of technology transition challenges, provides technology transition examples, and offers recommendations to improve the process.
... 00, its primary goal has, and continues to be, meeting surface ship requirements at the lowest possible cost. In addition to the IPS technical architecture implemented on DDG 1000, the Navy has also implemented more commercial IPS solutions to the T-AKE 1 class and a hybrid solution on LHD 8 and LHA 6. [Doerry and Davis 1994] [Doerry et. al. 1996] [Dalton et. al. 2002] The need for integrated power systems will increase in the coming decades. Figure 1 shows the projected propulsion and ship service power demands for future combatants armed with advanced sensors and future weapons such as railguns and lasers. Integrated propulsion systems are also projected to benefit the signature performance of futur ...
... Similarly, ships with the propulsion load considerably larger than the ship service load and operate infrequently at the maximum speed may benefit from a hybrid plant where the smaller PGMs produce 6 DOERRY Approved for Public Release power for ship service and low speed propulsion, and mechanical drive boast engines provide high speed operation. Makin Island, LHD 8, is an example of the latter configuration (Dalton et al. 2002). ...
The Navy recently produced a Next Generation Integrated Power System (NGIPS) Technology Development Roadmap that establishes the Navy's goal of incorporating a Medium Voltage DC (MVDC) Integrated Power System (IPS) in future surface combatants and submarines. For near term applications, NGIPS incorporates Medium Voltage AC (MVAC) and High Frequency AC (HFAC) power generation. All variants of NGIPS incorporate a Zonal Electrical Distribution System (ZEDS) that build off of the Integrated Fight Thru Power (IFTP) system developed for DDG 1000. More than a power system, NGIPS is an enterprise approach to develop and provide smaller, simpler, more affordable, and more capable power systems for all Navy ships. NGIPS is both a business and technical approach to define standards and interfaces, increase commonality among combatants (surface and subsurface), and efficiently use installed power. To promote commonality and acquisition efficiency, NGIPS implements an Open Architecture (OA) Business and Technical model. The NGIPS OA Business Model segregates the tasks of determining required capabilities, ship system engineering, architecting, module development, systems integration, and life cycle support. The NGIPS Technical Architecture includes a set of standards for ZEDS as well as power generation and distribution. This paper reviews why Integrated Power Systems (IPS) are advantageous for naval ships, briefly describes current ship designs incorporating an IPS, presents the NGIPS business and technical model, describes future opportunities for ship design innovations, and highlights aspects of NGIPS that require close attention and further development.
Volatile and rapidly rising energy costs are one of the top challenges for all nations and their defense organizations. Despite a reduction in force structure and increased conservation efforts over the past several years, the rapid increase in energy costs has placed significant pressure on the U.S. Navy budget. Reducing fuel consumption is an operational and strategic imperative and has a direct impact on improving warfighting effectiveness. The U.S. Navy is exploring opportunities to increase the energy efficiency of our non-nuclear ships and reduce total fossil fuel consumption across the fleet. This paper describes the efforts the U.S. Navy is currently undertaking as well as planning to accomplish to achieve these goals.
Selection of power and propulsion system architecture is one of the most far-reaching and irreversible decisions made by the designer of a modern ship. However, most texts and design handbooks pay little attention to the implications of this design decision nor is sufficient attention paid to the attributes of the various alternatives available to the ship designer/owner. Integrated power systems, made possible over the past three decades by the advances in modern high-power power electronics, provide many benefits to the ship owner, including reduced operating costs, arrangement flexibility, superior reliability and survivability, and support for advanced weapons on sensors warships. This paper will outline the architecture options available to today’s ship designer and will discuss the design implications and pitfalls inherent in the power system architecture selection, paying particular attention to the unique aspects of integrated power systems.
The early detection of incipient faults is desirable in mission-critical applications such as shipboard propulsion drives. This paper presents an online condition-monitoring approach for detecting early stage faults in IGBTs. The proposed algorithm extracts important device features (i.e. on-state resistance, gate charge, etc.) and compares them to healthy values recorded over a range of operating conditions. The algorithm is based on principal-components analysis (PCA). An experimental implementation in an IGBT-based drive is described, and results recorded with two different faults over a range of operating conditions are presented. The scheme integrates well with new FPGA-based gate drives and provides a powerful alternative to rules-based fault detection.
