Nonlinear Phenomenon and Efficient Nonlinear Control Techniques for DC-DC Power Converters

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The increase in the energy demands and high-performance systems has led to an increase in number power electronic devices. To achieve high efficiency, it has become necessary to explore more efficient control methods and techniques to meet modern quality standards and device specifications. This dissertation addresses issues in regards to the nonlinear phenomenon and nonlinear control techniques for switching power converters. This research address the issues with the following contribution. This dissertation first characterizes DC-DC converters targeting non-minimum phase systems with the change in sampling instant of the switch. Further, to validate the analysis experimentally, a practical frequency response function measurement device is implemented called as the Gain and Phase (GAP) measurement device. The GAP device has the ability to measure system response as a function of sampling time/sampling instant and is integrated with a graphical user interface which can be used to design a linear controller and measure important system parameters. Further, this dissertation explores efficient two nonlinear control algorithms. The proposed algorithms targets non-minimum phase DC-DC converters like the boost DC-DC converter. The boost converter intrinsically has unstable internal dynamics and is unstable when loaded with a nonlinear constant power load. The dissertation proposes a nonlinear control technique to stabilize the overall closed loop boost converter when loaded with constant power load. Further, the dissertation extends to another non-linear control technique for a boost converter for direct voltage regulation when loaded by resistive loads. Lastly, this dissertation proposed a higher resolution Direct Digital Synthesis (DDS) based DPWM architecture to eliminate a nonlinear phenomenon called steady-state limit cycle oscillation (LCO) which commonly exist in digitally controlled SMPS. The proposed architecture addresses numerous application with numerous advantages

Nonlinear control theory, DC-to-DC converters, Passivity-based control, Pulse-duration modulation
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