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Technical Paper

A Modular Power System Architecture for Military and Commercial Electric Vehicles

Numerous modern military and commercial vehicles rely on portable, battery-powered sources for electric energy. Due to their highly specialized functions these vehicles are typically custom-designed, produced in limited numbers, and expensive. To mitigate the power system's contribution to these undesirable characteristics, this paper proposes a modular power system architecture consisting of “smart” power battery units (SPUs) that can be readily interconnected in numerous ways to provide distributed and coordinated system power management. The proposed SPUs contain a battery power source and a power electronics converter. They are compatible with multiple battery chemistries (or any energy storage device that can produce a terminal voltage), allowing them to be used with both existing and future energy storage technologies.
Journal Article

A Novel Pressure-Feedback Based Adaptive Control Method to Damp Instabilities in Hydraulic Machines

Excessive vibration and poor controllability occur in many mobile fluid power applications, with negative consequences as concerns operators' health and comfort as well as machine safety and productivity. This paper addresses the problem of reducing oscillations in fluid power machines presenting a novel control technique of general applicability. Strong nonlinearities of hydraulic systems and the unpredictable operating conditions of the specific application (e.g. uneven ground, varying loads, etc.) are the main challenges to the development of satisfactory general vibration damping methods. The state of the art methods are typically designed as a function of the specific application, and in many cases they introduce energy dissipation and/or system slowdown. This paper contributes to this research by introducing an energy efficient active damping method based on feedback signals from pressure sensors mounted on the flow control valve block.
Technical Paper

Polytopic Modeling and Lyapunov Stability Analysis of Power Electronics Systems

Power electronics based power distribution systems are inherently nonlinear often behaving as constant power loads. Stability analysis of such systems typically is limited to local behavior. Herein polytopic modeling techniques are presented. Classification of polytopic model equilibrium points is made and methods of determining uniform asymptotic stability are presented.
Technical Paper

Stability Analysis of a DC Power Electronics Based Distribution System

This paper illustrates the application of the generalized immittance space approach to the analysis of multi-bus interconnected power electronics based power distribution system. The paper sets forth the basic classifications of power converters in regard to stability analysis, a set of network reduction transformations, and illustrates the use of these reductions in order to analyze the stability of a zonal dc distribution system.
Journal Article

The Utility of Wide-Bandwidth Emulation to Evaluate Aircraft Power System Performance

The cost and complexity of aircraft power systems limit the number of integrated system evaluations that can be performed in hardware. As a result, evaluations are often performed using emulators to mimic components or subsystems. As an example, aircraft generation systems are often tested using an emulator that consists of a bank of resistors that are switched to represent the power draw of one or more actuators. In this research, consideration is given to modern wide bandwidth emulators (WBEs) that use power electronics and digital controls to obtain wide bandwidth control of power, current, or voltage. Specifically, this paper first looks at how well a WBE can emulate the impedance of a load when coupled to a real-time model. Capturing the impedance of loads and sources is important for accurately assessing the small-signal stability of a system.
Technical Paper

Externally Electro-Pneumatically Shifting System (E.P.S) to Install on Manual Transmissions

In this study, an Electro-pneumatic shifting system (E.P.S) has been designed to install on manual transmissions to make the selecting and shifting process faster and more reliable compared to manual systems. Shifting mechanism of a six speed gear box has been improved by using two tandem pneumatic cylinders, position sensors, pneumatic valves, and a controlling board based on AVR microcontroller. The central processing unit uses an electronic control system to provide the optimized operation of shift mechanism. This system can be easily adjusted in order to install externally on manual transmission systems without any changes on housing and transmission shift links.