| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | June 15, 2013 |
| Latest Amendment Date: | June 15, 2013 |
| Award Number: | 1335397 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Steve Schmid
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | September 1, 2013 |
| End Date: | August 31, 2018 (Estimated) |
| Total Intended Award Amount: | $250,001.00 |
| Total Awarded Amount to Date: | $250,001.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1000 HILLTOP CIR BALTIMORE MD US 21250-0001 (410)455-3140 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1000 Hilltop Circle Baltimore MD US 21250-0002 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Manufacturing Machines & Equip |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
The objective of this project is to theoretically and experimentally investigate novel drivetrains for wind turbines with infinitely variable speed converters (IVSCs) and variable electromotive-force generators (VEGs), which can reduce failures, cost, and power loss; harvest more wind power; and reduce the cost of wind energy. By mechanically converting a variable wind input speed to a constant output speed using an IVSC, which is an all-mechanical gear train with minimal speed variation, one can generate grid-compatible constant-frequency power without using a power converter. A novel concept of an eccentric motion system that differs from all other continuously variable transmissions will be investigated. Two new concepts of VEGs are investigated: a generator with an adjustable overlap between the rotor and the stator and a multiple-generator configuration. The proposed research integrates various subjects including kinematics, dynamics, control, and electromagnetics. New control theories and laws will be developed for IVSCs and VEGs and implemented.
Using an all-mechanical speed converter can generate cost savings from simpler assembly and lower maintenance. Besides wind energy generation, the new knowledge generated from this research can be used to develop water turbines to harvest current and tidal energy; new transmissions and VEGs for cars, trucks, military vehicles, and ships; motion controls for airplanes and construction machines; and energy harvesting devices for ocean wave energy and vibration energy from railway tracks. Various aspects of the proposed research will be adapted for educational purposes to students at all levels, from high school students to Ph.D. students. The infinitely variable motion control and energy harvesting concepts will be demonstrated to underserved high school students in a summer educational program to spark their interest in science and engineering and to expose them to engineering research. Students in different disciplines will be involved in different aspects of wind energy research; research results will be showcased at wind energy forums to arouse public awareness of clean energy.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
This grant has supported the research on new drivetrain systems for wind turbines at the University of Maryland, Baltimore County. The research focused on new modeling, design and control methods for geared infinitely-variable speed converters and variable electromotive-force generators (VEG). A new infinitely variable transmission (IVT) was developed to convert the power with a continuously variable input-to-output speed ratio using planetary gear sets and two scotch yoke systems; a noncircular gear pair design method was developed to improve smoothness and continuity of the motion curve of the IVT, and a nonlinear control system of the IVT system was developed based on its dynamic model. Since the IVT has a merit that it transmits the power with contact forces and not friction forces, the IVT can take a larger load than a continuously variable transmission with a belt-pulley system in low-speed conditions. Another achievement of the research is the development of a new VEG with an adjustable overlap between the rotor and the stator to expand the operational range of a regular generator through a robust active control strategy.
In addition, a modified incremental harmonic balance (IHB) method was developed for single- and multi-degree-of-freedom (DOF) systems with strong nonlinearities; a new spatial and temporal harmonic balance (STHB) method was developed for obtaining periodic steady-state responses of a one-dimensional second-order continuous system. To make the average of the input speed converge to a desired constant for any input power and output load, an integral time-delay feedback control combined with an open-loop control is used to adjust the speed ratio of the IVT. A time-delay variable that is an approximation of the average of the input speed is used as the feedback to control the changing rate of the speed ratio.
The new developments of this research can be used in other disciplines. For instance, the IVT can be used in vehicles that require large torques at low speeds. It can also be used in some equipment that requires a continuously variable input-to-output speed ratio. The scotch yoke system can be used to convert translational input speeds to rotational output speeds, which has applications to wind turbines, joints of robotics, and milling machine tools. The new noncircular gear design method can be used for continuously variable transmission systems in other disciplines, such as packaging and printing machines. The new VEG has a broad range of applications in hybrid vehicles, water turbines, and similar equipment. The VEG with the robust active control system can adjust the overlap ratio based on the desired output power at different rotor speeds for a specific application. The IVT and the VEG can improve fuel efficiency of hybrid vehicles; they can also expand operational ranges of wind turbines and water turbines and harness more power. The modified IHB method can be used for nonlinear wave propagation problems and other nonlinear steady-state vibration problems. For instance, the modified IHB method can be used to study nonlinear steady-state vibrations of gear systems and rotor systems. This research has led to numerous journal and conference publications on a diverse range of topics.
As an outcome of this research, the IVT was selected by General Motors as the winner in a world-wide competition for game-changing transmissions in 2013. This research has supported several Ph.D. and M.S. students and provided opportunities and experience in areas of gear system design, nonlinear dynamics, and control system development of drivetrain systems for them. Two Ph.D. students are currently assistant professors at the University of Alabama, Tuscaloosa and the University of North Carolina, Charlotte. Two US patents on geared infinitely variable transmission (US 9,222,558 B2) and the VEG (US 9,991,771 B2) were issued based on outcomes of the research.
Last Modified: 11/30/2018
Modified by: Weidong Zhu
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