Average and small signal modeling of zero-voltage transition three-phase boost rectifier is performed. The effect of ZVT is introduced in the existing model for the three-phase boost rectifier using the time-averaging equivalent circuit approach. The small signal model is derived from the average model. The small signal characteristics are compared to the corresponding characteristics without ZVT. A model is also developed for the independent analog current controller. The models are experimentally verified. In order to perform in-depth study of control approaches, a switching model is also developed. The models are used to investigate various control approaches. / Master of Science

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This work presents a modeling methodology that uses new types of models called low-frequency, large-signal models in a circuit simulator (Saber) to model a complex hybrid ac/dc power electronics system. The new achievement in this work is being able to model the different components as circuit-based models and to capture some of the large-signal phenomena, for example, real transient behavior of the system such as startup, inrush current and power flow directionality. In addition, models are capable of predicting most low frequency harmonics only seen in real switching detailed models. Therefore the new models system can be used to predict steady state performance, harmonics, stability and transients. This work discusses the modeling issues faced based on the author recent experiences both on component level and system level. In addition, it recommends proper solutions to these issues verified with simulations. This work also presents one of the new models in detail, a voltage source inverter (VSI), and explains how the model can be modified to capture low frequency harmonics that are usually phenomena modeled only with switching models. The process of implementing these different phenomena is discussed and the model is then validated by comparing the results of the proposed low frequency large signal (LFLS) model to a complete detailed switching model. In addition, experimental results are also obtained with a 2 kW voltage source inverter prototype to validate the proposed improved average model (LFLS model). In addition, a complete Verification, Validation, and Uncertainty Quantification (VV&UQ) procedures is applied to a two-level boost rectifier. The goal of this validation process is the improvement of the modeling procedure for power electronics systems, and the full assessment of the boost rectifier model predictive capabilities. Finally, the performance of the new models system is compared with the detailed switching models system. The LFLS models result in huge cut in simulation time (about 10 times difference) and also the ability to use large time step with the LFLS system and still capture all the information needed. Even though this low frequency large signal (LFLS) models system has wider capabilities than ideal average models system, it still can’t predict all switching phenomena. Therefore, another benefit of this modeling approach is the ability to mix different types of models (low frequency large signal (LFLS) and detailed switching) based on the application study they are used for. / Ph. D.

In this thesis, the investigation focuses on the analysis of the high frequency characteristics and the nonlinearity of the transistors. In view of the III-V semiconductors which have excellent high frequency performance and the advantage for high frequency circuit design, the 0.15£gm InGaAs based pseudomorphic high electron mobility transistors provided by WIN semiconductor Corp. were used in this study. The high frequency measurement was utilized to extract both extrinsic and intrinsic components of the transistors, and further to establish the small signal equivalent model in each bias condition. According to the physical definition of the extracted gm, gds and the relationship with the output current, RF I-V curves could be determined through the integration procedure. The nonlinearity of the transistors can be attributed to the nonlinear input capacitance Cgs and Cgd, and the voltage dependent current source. The high frequency nonlinear models proposed in this thesis were based on classic Angelov model. For the high frequency application, the frequency dependent characteristics of the nonlinear sources would be taken into consideration through the combination of the RF I-V curves and extracted intrinsic components. Thus, the nonlinearities could be able to describe by nonlinear function through the fitting process and model the output performance completely. The accuracy of the models could be confirmed through the comparison between the simulation and the measurement result. Obviously, the high frequency models which include the high frequency effect and the nonlinear characteristics have excellent agreement with the experimental data.