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Ultra-Low Ripple 1000 Volt Direct Current Battery Charger


TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace 

OBJECTIVE: Develop innovative high-bandwidth, tunable, compact, high-efficiency battery chargers providing significantly reduced voltage and current ripple for high-power battery systems. 

DESCRIPTION: The Navy is seeking an Ultra-Low Ripple 1000 Volt Direct Current (1kV DC) battery charging system capable of maintaining high-density 1kV battery banks. The Navy has requirements for a charger to maintain a high-power, energy-dense storage battery capable of supporting pulse-type loads. The ability to provide sustained and maintenance type battery charging of electric weapon systems, with batteries that are in continuous use is a key enabler to the future of electric weapons and high energy loads in the fleet. Typical power conversion systems are either very large, and/or have high power ripple and poor power quality under various modes of use. Battery chargers that reduce battery degradation due to low/no ripple, while providing a smaller footprint by innovatively leveraging recent commercial advances in high-bandwidth power for conversion components and topologies are needed. This innovation will ensure highly compact and efficient power supplies offering significantly reduced voltage and current ripple ensuring longer battery life and better performance. The product of this effort should allow real-time tuning and optimized charging in a manner that best aligns to large battery systems for high-energy weapons such as lasers and railguns. Battery systems have an intrinsic sensitivity to current and voltage ripple under charging and float-type maintenance. Variations in the charging power create scenarios where higher levels of heating can occur within the cells due to the ripple induced current flow, as well as higher than desired voltage spikes, which can facilitate oxidation and other degrading conditions. Present-day silicon devices are large, inefficient, and do not offer sufficiently fast switching frequencies to minimize ripple and DC artifacts when charging batteries. New commercial innovations in high-bandwidth materials are enabling significantly smaller consumer electronics. This topic seeks technologies for charging much larger battery systems in a military setting. These innovations need to be tunable, compact, and highly efficient battery charging power supplies that can be common to multiple uses. By utilizing advanced charging methodologies, there will be less stress on the batteries, which will require less operational maintenance and provide longer battery life, reducing cost. By leveraging high-bandwidth materials (silicon carbide (SiC), gallium nitride (GaN)) as an enabling technology applied to efficiently charging large battery systems, the Navy expects to optimize Space, Weight, Power, and Cooling (SWaP-C). The Navy desires research to leverage recent advancements in commercial power electronic switching technologies such as the use of solid state switching and advanced materials in power electronics in order to create a unidirectional charging converter. The charger controls, programming, components, and input/output must hold to available IEEE and NEC 2017 design standards while maintaining the highest levels of safety and efficiency. The design should also include the self-diagnosis of anomalous behaviors and potential damaging conditions such under or over voltages, overcurrent conditions, out-of-range temperature readings, or changes in the response characteristics of the target battery system. Designs should produce options that have minimal losses and require minimal thermal management as a result. They should provide clean power at all output conditions, and ensure that no irregular power quality issues are caused for the sourcing power system. Operational requirements include: - Interface (power input): 450VAC compliant to IEEE 1399-300 spec. - Galvanically isolated - Fault protection on both input and output - Charging output: 30mA-30A per LRU across the voltage range of 650-1100VDC - Ability to scale by paralleling to increase charging rate/power - Ripple level: less than 0.25% RMS of float and peak charging voltage - Power density: greater than 3MW/m3 - Efficiency: greater than 96.5% - Cooling: Passive (objective); 40C Water (threshold) - Non-proprietary controls and data logging interfaces - Charging modes: variations and combinations of constant current, constant voltage, and constant power, as well as custom profiles - Dissipation capability: Capable of removing less than or equal 1kWh of energy from a battery charged to 1kV at low rate and controlled output. - Designed for grade A shock and shipboard vibration - Designed for EMI compliance, input and output conductors shielded and suitably terminated 

PHASE I: Develop a concept for a 1kV battery charging system capable of maintaining high-density 1kV battery banks. Demonstrate the viability of the concept in meeting Navy requirements described above, and establish that the system can be feasibly developed into a useful product for the Navy. Feasibility will be established by modeling and simulation of a battery system of appropriate scale and technology. The Phase I Option, if awarded, will address technical risk reduction and provide performance goals and key technical milestones. Phase I will include creating plans for prototype development during Phase II. 

PHASE II: Based on the results of Phase I and the Phase II Statement of Work (SOW), develop and deliver a prototype to the Navy for evaluation in a relevant environment. Demonstrate system performance through evaluation in a laboratory environment and modeling or analytical methods over the required range of parameters to demonstrate ability to meet the performance goals defined in the Phase II SOW and the Navy requirements for a charger to maintain a high-power, energy-dense storage battery capable of supporting pulse-type loads. Use evaluation results to refine the prototype into a design that will meet Navy requirements as cited in the Phase II SOW. Conduct performance integration and risk assessments, and develop a cost-benefit analysis and cost estimate for a Naval shipboard unit. Prepare a Phase III development plan to transition the technology to Navy and potential commercial use. 

PHASE III: Support the Navy in evaluating the system delivered in Phase II. Based on analysis performed during Phase II, recommend test fixtures and methodologies to support environmental, shock (MIL-S-901D), and vibration (MIL-STD-167-1A) testing and qualification. The company and the Navy will jointly determine appropriate systems for replacement of current battery charger with the SBIR-developed system for operational evaluation, including required safety testing and certification. Working with the Navy, demonstrate the battery charger on a relevant system to support directed energy weapons and electronic warfare. Provide detailed drawings, code, and specifications in defined format. Transition opportunities for this technology include charging and charge maintenance of high-power battery systems in ship-wide stable backup power systems and energy storage systems that are widely used in large industrial applications, utilities, and back-up systems. 


1: Uddin, Kotub, Moore, Andrew D., Barai, Anup, and Marco, James. "The effects of high frequency current ripple on electric vehicle battery performance." Applied Energy, Volume 178, 15 September 2016, p. 142-154, ISSN 0306-2619.

2:  "Charger Output AC Ripple Voltage and the effect on VRLA batteries." C&D Technologies Inc, C&D Technical Bulletin 41-2131.

3:  De Breucker, Sven. "Impact of DC-DC Converters on Li-ion Batteries." Kathoieke Univeriteit Leuven, December 2012.

KEYWORDS: 1000V Direct Current Battery Charger; High Switching Frequency; Galvanically Isolated; Advanced Battery Chargers; Silicon Carbide (SiC) Electronics; High Power Ripple 


John Heinzel 

(215) 897-1413 

Mr. Mike Giuliano 

(215) 897-1722 

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