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Average-value modeling of dc-dc converters has been an area of active research for many years. Developing accurate average-value models of higher order converters is further complicated by the presence of parasitics and waveform nonlinearity. This paper extends the numerical state-space averaging to the fourth-order capacitor-based switching stages. The proposed model takes into account conduction losses associated with switching-stage components and is scamlessly functional in all operational modes. The proposed model is validated with a hardware prototype and detailed simulation and is shown to accurately predict large-signal time-domain transients as well as small-signal frequency-domain characteristics. Index Terms--Average-value modeling, Cuk converter, dynamic characterization, PWM dc-dc converters.

This manuscript addresses dynamic average-value modeling for fourth-order pulse-width modulation (PWM) dc-dc converters in discontinuous capacitor-voltage mode. Although significant literature is devoted to analysis of the inductor-based switching stage of second-order dc-dc converters in discontinuous current mode, much less has been published regarding the dis- v continuous voltage mode in the capacitor-based switching stage in fourth-order converters. Accurate average-value models are further complicated by the presence of non-ideality in the switching stage components. This manuscript presents a full-order average-value model for the capacitor-based switching stage, taking into account conduction losses according to the energy conservation principle. The proposed model is validated with a hardware prototype and detailed simulation and is shown to accurately predict large-signal time-domain transients as well as small-signal frequency-domain characteristics. Index Terms--Average value modeling, DC-DC converters, discontinuous capacitor voltage mode (DCVM), parasitics, pulsewidth modulation (PWM).

Analytical average-value modeling of pulsewidth modulation dc-dc converters is usually based on the piece-wise linear waveforms of the circuit variables and neglects the parasitics that give rise to waveform nonlinearities and complicate model derivation. This letter presents a straightforward but powerful methodology that considers the true averaging of nonlinear waveforms and produces a fairly accurate large-signal transient model that is functional in both operational modes. Based on the proposed modeling approach, a fast procedure for extracting the small-signal frequency-domain characteristics is set forth. The key model parameters are established numerically using the detailed simulation, which streamlines the analysis. The resulting average-value model is validated with a hardware prototype, a detailed simulation, and several previously established models in time and frequency domains. Index Terms--Average-value modeling, parasitics, pulsewidth modulation (PWM) dc--dc converters, state-space averaging (SSA).

State-space average-value modeling of pulsewidth modulation converters in continuous and discontinuous modes has received significant attention in the literature, and various models have been developed. This paper presents a new approach for generating the state-space average-value model. In the proposed methodology, the so-called duty-ratio constraint and the correction term are extracted numerically using the detailed simulation and are expressed as nonlinear functions of the duty cycle and average-value of the fast state variable. The parasitic effects of circuit elements are readily included. The resulting average-value model is compared to a hardware prototype, a detailed simulation, and several previously published models. The proposed model is shown to be very accurate in predicting the large-signal time-domain transients as well as the small-signal frequency-domain characteristics. Index Terms--Average-value modeling, dc-dc converters, discontinuous conduction mode (DCM), state-space averaging.

The analytical derivation of the average-value models (AVMs) for synchronous-machine-fed rectifier systems depends on many factors and is challenging in general. Various models presented in the literature rely on a single operating mode and a dc filter configuration. A recently proposed parametric approach utilizes a detailed simulation as a basis to establish an AVM that uses a proper full-order qd generator model. This paper presents a procedure to extract the appropriate nonlinear algebraic functions to represent the rectifier averaged behavior. In contrast to existing methods, the proposed procedure does not require significant analytical derivations and/or computational resources and results in a highly accurate dynamic AVM. The proposed methodology is validated with the results of detailed simulation and hardware experiment, and is shown to be very accurate in predicting the large-signal time-domain transients as well as the small-signal frequency-domain characteristics. Index Terms--Average-value model, impedance characterization, line-commutated rectifier, synchronous machine.

A new average-value model of a rectifier circuit in a synchronous-machine-fed rectifier system is set forth. In the proposed approach, a proper state model of the synchronous machine in the qd-rotor reference frame is used, whereas the rectifier/dc-link dynamics are represented using a suitable proper transfer function and a set of nonlinear algebraic functions that are obtained from the detailed model using numerical averaging. The new model is compared to a detailed simulation as well as to measured data and is shown to be very accurate in predicting the large-signal time-domain transients as well as small-signal frequency-domain characteristics. Index Terms--Average-value model (AVM), impedance characterization, line-commutated rectifier, synchronous machine.