1,721,182 research outputs found
Design of a robust voltage controller for a buck-boost converter using mu-synthesis
No full textThis paper proposes the structured singular value (mu) approach to the problem of designing an output voltage regulator for a Buck-Boost converter with current-mode control. This approach allows a quantitative description of the effects of reactive components’ tolerances and operating point variations, which strongly affect the converter dynamics. At first, a suitable linear converter model is derived, whose parameter variations are described in terms of perturbations of the linear fractional transformation (LFT) class. Then, mu-analysis is used to evaluate
the robustness of a conventional PI voltage regulator with respect to the modeled perturbations. Finally, the approximate
mu-synthesis procedure known as D-K iteration is used to design a robustly performing regulator. Simulation results are presented,
describing the small and large signal behavior of a reduced order
approximation of the mu-synthesized controller
Small-Signal Modeling of the Interleaved Boost with Coupled Inductors Converter
No full textThis paper aims to investigate the dynamic behavior of an isolated converter topology suitable for high step-up applications, i.e the Interleaved Boost with Coupled Inductors (IBCI). Such topology, presented in literature with the alternative name of active-clamp flyback-forward converter,
has interesting characteristics such as continuous input current, soft-switching operation in a wide load range and high step-up capability with limited switch voltage stress.
While the converter steady-state operation is well understood, its dynamic behavior still needs investigation. The purpose of this paper is to fill this gap by proposing a non-linear average model that, under small-signal approximation, can be linearized around a given operating point. Different transfer functions are then derived, that allow an exhaustive converter dynamic analysis. Experimental measurements, taken on a 300W prototype, verify the theoretical forecasts
A New Soft-Switching Forward DC-DC Converter Operating in Discontinuous Conduction Mode
No full textThe paper presents a simple soft-switching forward DC-DC converter suitable for low power applications. A lossless passive turn-off snubber is employed to provide zero voltage turn off of the switch as well as transformer reset. Moreover, the choice to operate the converter in discontinuous conduction mode (DCM), while providing zero current turn on of the switch, also allows to simplify the topology by eliminating the inductive output filter.
A detailed converter analysis, aimed to highlight advantages and drawbacks of the presented topology, is reported, together with a suitable design procedure. Experimental results are also included to verify the theoretical expectations
Analysis of the Interleaved Isolated Boost Converter with Coupled Inductors
No full textThis paper analyzes the Interleaved Boost with Coupled Inductors (IBCI) converter, an isolated topology that is suitable for high step-up applications. Two main contributions are given: an exhaustive steady-state analysis and an accurate small signal model.
The former allows to derive a closed-form, non iterative, design procedure for the power stage active and passive components. In addition, it reveals an interesting equivalence with an apparently different converter, the Single Active Bridge (SAB).
Subsequently, the IBCI converter dynamic behavior is investigated, deriving a non-linear average model that, under small-signal approximation, can be linearized around a given operating point and used for feedback controller design.
A single photovoltaic module interface converter, rated for 300W output power, is considered as a case study to validate the analysis outcomes and the design procedure. Both are fully validated by measurements taken on the laboratory prototype
Small-Signal Analysis of Cold Cathode Fluorescent Lamp Ballasts
No full textA small-signal linear model of a cold cathode fluorescent
lamp (CCFL) ballast that employs a voltage-driven piezoelectric
transformer is presented. The model takes into account the
lamp dynamic and is based on the application of the generalized
averaging method presented in [1]. The derived model can be used
for stability analysis purposes and is able to predict instabilities observed in different experimental setups
Analysis of Instabilities in Piezoelectric Transformers Driving Cold Cathode Fluorescent Lamps
No full textThis paper analyzes the behavior of power supplies for cold cathode fluorescent lamps (CCFL) employing piezoelectric transformers (PTs). It has been demonstrated that the non-linear equivalent lamp resistance interacts with the PT that behaves like a high-Q resonant circuit, giving rise to instabilities in the audible frequency range [Spiazzi, G. et al. 2004]. Moreover, when the PTs are driven by a voltage-fed inverter and its DC supply voltage is used to control the lamp voltage, the relation between the control variable and the lamp current can become nonmonotonic, depending also on the coupling network used between the inverter and the PT. This paper extends the analysis reported in Spiazzi, G. et al. (2004) by considering different coupling networks as well as considering the inverter switching frequency as the control variable for controlling the lamp current. SPICE simulations and analytical models are employed to explain the unstable behaviors observed in different experimental prototypes
Digital control in power electronics
No full textThis book presents the reader, whether an electrical engineering student in power electronics or a design engineer, some typical power converter control problems and their basic digital solutions, based on the most widespread digital control techniques. The presentation is focused on different applications of the same power converter topology, the half-bridge voltage source inverter, considered both in its single- and three-phase implementation. This is chosen as the case study because, besides being simple and well known, it allows the discussion of a significant spectrum of the more frequen
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