June 15, 2014
June 15, 2014
June 18, 2014
24.378.1 - 24.378.19
Designing Hybrid Energy Storage Systems: A Tool for Teaching System-Level Modeling and SimulationThe hybrid energy storage system (HESS) concept is gaining importance in applications requiring loadleveling, high-density energy storage, and emergency power. Energy sources used in modern HESSinclude high performance batteries such as Li-Ion, ultracapacitors, and flywheels. HESS provides anexcellent platform to teach system-level modeling and simulation while integrating aspects of electrical,mechanical, and thermal systems. Circuit-level models of energy storage devices such as batteries andultracapacitors can be developed from manufacturer provided performance characteristics. Similarly, acircuit-level model of a generator can be developed from its terminal characteristics and electromagneticparameters. An example HESS for avionics applications, shown in Figure 1, connects various energysources to the dc power bus via dc-dc power converters. These bidirectional power converters play akey role in designing HESSs since they let energy sources of various voltage and power levels supportthe bidirectional system load in a controlled and predictable manner. Additionally, energy-dense andpower-dense storage devices can be integrated to optimize the weight and performance of HESSs byeffective use of dc-dc power converters. Accordingly, modeling of a switching power converter of thetype shown in Figure 2 is an integral part of the HESS design and implementation process.The full paper will explore the modeling and simulation of HESSs using the Matlab/Simulink software.Various subsystems can be developed to model the energy sources, dc-dc converters, and loads. The dc-dc power converters will be analyzed to develop switching as well as average models. Varioussubsystems will be connected to develop multiple HESS configurations. A supervisory controlalgorithm will be implemented to control the sharing of power and energy among various energysources for supporting bidirectional loads. One of the goals of this HESS modeling and simulationeffort is to optimize the design in terms of electrical and thermal performance, power and energyefficiency, mass, and volume of the overall system.From a pedagogical point of view, modeling and simulation of HESSs presents an excellent platform tointegrate various curricular content including modern energy storage devices, electrical and electroniccircuits, electrical machines and power systems, electromechanical systems, signals and systems, controlsystems, and power electronics. Through this modeling and simulation activity, students becomefamiliar with system-level design from both top-down (system-level to component-level) and bottom-up(component-level to system-level) perspectives including an appreciation for multimode systems andsystem reliability. 270 VDC Bus Synchronous generator with Buck output rectifier (270 V) Battery pack DC/DC (345 V) Converter Unidirectional Continuous Load V_1 V_2 + Bidirectional Transient LoadUltracapacitor DC/DC bank Converter (250 V) BoostFigure 1: An example HESS system. Figure 2: Bidirectional buck/boost converter.
Ray, B. (2014, June), Designing Hybrid Energy Storage Systems: A Tool for Teaching System-Level Modeling and Simulation Paper presented at 2014 ASEE Annual Conference & Exposition, Indianapolis, Indiana. 10.18260/1-2--20269
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