Steady-state analysis of PWM DC-to-DC regulators

A new method for steady-state analysis of pulsewidth modulation (PWM) hard-switching DC-to-DC regulators is presented. The power stage and the feedback control circuit are analyzed as two interconnected blocks. The intersection of their open-loop DC steady-state characteristics with the ramp voltage provides a guess candidate steady-state solution (CS). An iterative process is used to validate it as true steady-state solution (TS) when the bias conditions of switching devices (SDs) are fulfilled everywhere in the switching period.     

Understanding commutations in switching converters. I. Basic theory and application of the Compensation Theorem

The analysis of synchronous commutations in switching converters is discussed. A reduced resistive circuit for the analysis of synchronous commutations is introduced by applying the Compensation Theorem. Based on a matrix model, a new method for the analysis of both hard and soft synchronous commutations is formulated, which permits a straightforward understanding operation of switching converters. The method of analysis is presented herein in its basic version, for the analysis of nonisolated hard-switching converters, while the general formulation and its applications to the analysis and synthesis of DC-DC regulators is presented in the companion paper Part II.     

Optimized one-cycle control in photovoltaic grid connected applications

The use of one-cycle control (OCC) for maximum power point tracking (MPPT) and power factor correction (PFC) in grid connected photovoltaic (PV) applications is discussed. Circuit and operating parameters of the one cycle-based controller of a cost-effective single-stage inverter are optimized in order to obtain the best performances of the system under different irradiance levels. Firstly, design constraints are formulated which allow to get a very efficient OCC operation in terms of power extracted from the PV array, stability, and PFC. Afterwards, such constraints are used to perform the parametric optimization of the one cycle controller by means of suitable heuristic approaches. Various selection criteria of the best parameters set under different conditions are discussed and applied. Finally, a customized perturb and observe (P&O) control is applied to the optimized one cycle controlled single-stage inverter in order to perform a real MPPT in presence of varying irradiance conditions. Subjects described here are covered by the Italian Patent Application SA2005A000014-13.07.2005 and PCT Application PCT/IT2005/000747-20.12.2005     

Understanding commutations in switching converters. II. Analysis and synthesis of DC-DC regulators

For pt.I see ibid., vol.39, no.1, p. 282-297 (2003). This paper illustrates a general method to formulate the equations for the analysis of commutations and of the effects caused by large step-wise perturbations, large change of parameters, and circuit failures in switching converters including transformers, feedback circuitry, and soft-switching cells. The matrix equations obtained by means of the modified nodal analysis-based method proposed in this work are useful for theoretical inspection of switching converters as well as for numerical simulations. The examples of applications concern the analysis and the synthesis of switching converters and show that the Compensation Theorem (CT)-based model may help in selecting circuit topologies valid for the circuit design.