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Stability is an essential indicator of proper system operation. To this end, it is often of interest to predict the Region of Asymptotic Stability (RAS) associated with an equilibrium point of interest. In the case of the presence of constraints that need to be satisfied, one is faced with the problem of estimating a Restricted RAS (RRAS). Practical methods for estimating RRASs have been proposed and demonstrated for relatively high-order systems. These methods are based on Lyapunov's second method. However, they do not address the problem of constructing an optimal Lyapunov function. In this paper, a method of finding a Lyapunov function that yields improved estimates of the restricted region of asymptotic stability is set forth. In addition, a new method for estimating RRASs based on the average of the Lyapunov derivative is also set forth. Numerical examples illustrate the utility of the proposed methods.

High performance high bandwidth control of power electronic converters, inverters, and motor drives has become feasible over the past decade. These devices behave as constant power loads over large bandwidths when they are tightly regulated. However, constant power loads have a severe side affect known as negative impedance instability. In order to mitigate the problem of negative impedance instability a new nonlinear system stabilizing controller has been developed. The details of how this controller works along with its implementation is discussed and demonstrated in hardware.

The purpose of this paper is to review the modeling techniques, stability analysis, and design criteria relevant to the design of power electronics based systems (PEBS) such as dc power systems in aircraft. Throughout this discussion these techniques, analysis, and criteria are applied to a laboratory test system in order to illustrate the use and validity of the techniques discussed.

The method of multiple reference frames is employed in the development of a state variable model for brushless DC drives with non-sinusoidal back emf waveforms. This model has the desirable features of being valid for transient and steady-state analysis as well as having state variables that are constant in the steady-state. The model facilitates both nonlinear and linear system analysis and control design. Computer simulation and experimental data are included to validate the analysis.

The auxiliary resonant commutated pole (ARCP) converter is currently of intense interest for use in a variety of power electronic converters, and is one of the cornerstones of the Navy's Power Electronic Building Block (PEBB) effort. In this paper a detailed discussion of the required switching times needed to achieve completely soft switching operation with only one current sensor per phase is set forth. Based on this analysis, an average-value model of the ARCP converter is derived and used to explore the output characteristics of the ARCP converter. It is shown that large loads at high power factors can cause the ARCP output voltage to drop substantially. Computer simulations and laboratory data are used to validate this analysis.

The steady-state and dynamic performance of a candidate aircraft power distribution system is considered. The system features distribution of both single phase 20-kHz and three-phase 400-Hz power. It is shown that unlike some other recent 20-kHz systems, the power quality of the 20-kHz bus is not a concern due to the use of a synchronous bi-directional rectifier (SBR) as the primary interface to the 20-kHz bus. In addition to showing that the system behaves adequately in the steady-state, the dynamic performance of the system is considered during step changes in load, bolted faults, and sudden variations in jet engine speed.