Master of Science in Mechanical Engineering, Cleveland State University, 2021, Washkewicz College of Engineering

Recent developments in aircraft propulsion electrification are motivated by economic and environmental factors such as lowering greenhouse gas emissions, reducing noise, and increasing fuel efficiency. This thesis focuses on a hybrid gas-electric propulsion concept combining a gas turbine jet engine with an electromechanical (EM) system. An optimal control system allows energy to be recovered from the gas turbine engine or injected into it from an electric storage unit. Energy extraction or injection can be obtained by selecting a performance weight in the optimization function that trades off fuel consumption with stored electrical energy utilization. The goal of this research is to validate the effectiveness and plausibility of the optimal controller during representative acceleration and deceleration maneuvers and at steady state. To accomplish this, the gas turbine engine dynamics are simulated using NASA's T-MATS package and used in a hardware co-simulation approach along with physical hardware representative of the EM system, namely motors, power converter, and an energy storage device. A time scaling methodology was used to reconcile the power levels of the physical EM system (in the order of a kilowatt) with those of the engine simulation (in the order of megawatts). Multiple steady state missions were represented within a full simulation environment and in the lab test environment that covered a wide range of fuel-electric optimization weights. In addition, a chop-burst study was conducted to ensure the readiness of the system to handle flight missions. Based upon captured data, specifically that of shaft torque, supercapacitor voltage, and fuel flow measurements, it was determined that the optimal control objective was met. An increase in fuel-electric optimization weight corresponded to a desired change in torque to the engine and voltage to the energy storage device.

Committee: Hanz Richter (Advisor); Jerzy Sawicki (Committee Member); Lili Dong (Committee Member) Subjects: Engineering; Mechanical Engineering

Doctor of Philosophy in Engineering, Cleveland State University, 2019, Washkewicz College of Engineering

We investigate the control and optimization of robots with ultracapacitor based regenerative drive systems. A subset of the robot joints are conventional, in the sense that external power is used for actuation. Other joints are energetically self-contained passive systems that use ultracapacitors for energy storage. An electrical interconnection known as the star configuration is considered for the regenerative drives that allows for direct electric energy redistribution among joints, and enables higher energy utilization efficiencies. A semi-active virtual control strategy is used to achieve control objectives. We find closed-form expressions for the optimal robot and actuator parameters (link lengths, gear ratios, etc.) that maximize energy regeneration between any two times, given motion trajectories. In addition, we solve several trajectory optimization problems for maximizing energy regeneration that admit closed-form solutions, given system parameters. Optimal solutions are shown to be global and unique. In addition, closed-form expressions are provided for the maximum attainable energy. This theoretical maximum places limits on the amount of energy that can be recovered. Numerical examples are provided in each case to demonstrate the results. For problems that don't admit analytical solutions, we formulate the general nonlinear optimal control problem, and solve it numerically, based on the direct collocation method. The optimization problem, its numerical solution and an experimental evaluation are demonstrated using a PUMA manipulator with custom regenerative drives. Power flows, stored regenerative energy and efficiency are evaluated. Experimental results show that when following optimal trajectories, a reduction of about 10-22% in energy consumption can be achieved. Furthermore, we present the design, control, and experimental evaluation of an energy regenerative powered transfemoral prosthesis. Our prosthesis prototype is comprised of a passive (open full item for complete abstract)

Committee: Hanz Richter (Advisor); Dan Simon (Committee Member); Eric Schearer (Committee Member); Antonie van den Bogert (Committee Member); Ulrich Zurcher (Committee Member) Subjects: Engineering; Mechanical Engineering; Robotics

Doctor of Engineering, Cleveland State University, 2017, Washkewicz College of Engineering

High Intensity Laser Power Beaming is a wireless power transmission technology developed at the Industrial Space Systems Laboratory from 2005 through 2010, in collaboration with the Air Force Research Laboratory to enable remote optical `refueling' of airborne electric micro unmanned air vehicles. Continuous tracking of these air vehicles with high intensity lasers while in-flight for tens of minutes to recharge the on-board battery system is not operationally practical; hence the recharge time must be minimized. This dissertation presents the development and system design optimization of a hybrid electrical energy storage system as a solution to this practical limitation. The solution is based on the development of a high energy density integrated system to capture and store pulsed energy. The system makes use of ultracapacitors to capture the energy at rapid charge rates, while lithium-ion batteries provide the long-term energy density, in order to maximize the duration of operations and minimize the mass requirements. A design tool employing a genetic algorithm global optimizer was developed to select the front-end ultracapacitor elements. The simulation model and results demonstrate the feasibility of the solution. The hybrid energy storage system is also optimized at the system-level for maximum end-to-end power transfer efficiency. System response optimization results and corresponding sensitivity analysis results are presented. Lastly, the ultrafast supply/extended energy storage system is generalized for other applications such as high-power commercial, industrial, and aerospace applications.

Committee: Hanz Richter Ph.D. (Committee Chair); Taysir Nayfeh Ph.D. (Committee Member); Lili Dong Ph.D. (Committee Member); Majid Rashidi Ph.D. (Committee Member); Petru Fodor Ph.D. (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, University of Toledo, 2005, Electrical Engineering

The nickel metal hydride (NiMH) batteries used in most hybrid electric vehicles (HEVs) provide satisfactory performance but are quite expensive. In spite of their lower energy density, lead acid batteries are much more economical, but they are prone to sulfation in HEV applications. However, sulfation can be greatly reduced by a circuit that uses an ultracapacitor in conjunction with the battery. This research presents a new cost-effective method for using these two energy storage components together in order to extend the life of the battery. This system is presently quite expensive, but it will provide much cheaper energy storage if ultracapacitor prices can be reduced to the levels predicted by some manufacturers. This dissertation studies two different methods for implementation on a hybrid electric vehicle and presents performance data for a variety of simulations.

Committee: Thomas Stuart (Advisor) Subjects:

Master of Science, University of Akron, 2008, Electrical Engineering

In this thesis several short-term models and a long-term model have been developed for a NESSCAP3500P ultracapacitor. For the short-term ultracapacitor models, first-, second-, third- and fourth-order transfer functions consistent with an RC ladder model are assumed. The transfer function coefficients are identified by a least squares algorithm based on experimental data consisting of time-varying current excitations and the resulting terminal voltage responses.A long-term model with six RC branches is developed by fitting the terminal voltage transient response to an impulse charging current. Hundreds of thousands of terminal voltage data points are recorded and least squares identification is employed to determine the optimal values of the unknown parameters in the long-term model. From the ultracapacitor models derived, terminal voltages under different current profiles can be determined accurately over the time frame of one hour with an error less than 0.1 V, the impulse charging and discharging response over a time frame of two months can be simulated with an error less than 0.08 V, and the instantaneous power available can be calculated.

Committee: Joan Carletta (Advisor); Robert Veillette (Advisor); Tom Hartley (Advisor) Subjects: Electrical Engineering; Energy; Engineering; Technology