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Digital control system applied to a PFC boost converter operating in mixed conduction mode

This paper proposes a digital control system applied to a power factor correction boost converter rated to a wide range of output power, operating in mixed conduction mode with fixed switching frequency. The control system is composed of an input current controller and an output voltage controller. The current controller comprises two predictive model-based control laws (one for the continuous conduction mode and another for the discontinuous conduction mode) and an operation mode selection algorithm, which is responsible for detecting the operation mode and selecting the appropriate control law. The output voltage is regulated using a proportional-integral voltage controller. Simulation and experimental results applying a low cost microcontroller are shown to ensure the operation of the proposed control system.

A comparison of high power single-phase power factor correction pre-regulators

In this paper, a comparison of three high power single-phase power factor correction (PFC) pre-regulators is proposed. The topologies discussed are the boost converter, the interleaved boost converter and the dual boost converter. The control system used to perform the PFC is based in predictive current control laws and an algorithm to detect the conduction modes is also used, once the converters operate in mixed conduction mode. All topologies have the same input current, input voltage, output voltage, load and controller. Furthermore, all topologies have the same rms current and total harmonic distortion (THD) values of the input current, and, therefore, equal input filters. The comparison parameters are: input power factor, conducted electromagnetic interference (EMI), core losses, power losses, heat-sink volume, total volume, efficiency and number of components and devices. Theoretical and experimental results are presented to analyze the comparisons between the converters.

A static converter comparative study taking into account semiconductor tecnologies and swicth auxiliary circuits: Optimized design

The optimized static converter design is directly related to the appropriate choice of operation point (Δi @ fs). The magnetic elements like inductor and noise filter, and thermal elements like heat sink are which main influences in the converter volume. These elements are strongly influenced by the chosen operation point, showing a direct relationship among them [1]. With the increase of both the switching frequency and the input current ripple occurs reduction of the inductor volume. On the other hand, it increases the switching losses into semiconductors and influence on the EMI filter volume.

Implementation issues of a digital control system applied to a PFC boost converter

This paper presents implementation issues of a digital control system applied to a power factor correction (PFC) boost converter rated to a wide range of output power, operating in mixed conduction mode (MCM). The digital control system comprises an input current controller and an output voltage controller. The current controller is formed by two predictive model-based control laws, while the output voltage is regulated through a proportional-integral controller. The implementation requirements of this control system and the executed programming routines, highlighting the inductor current sampling process in different conduction modes are discussed. Experimental results applying a low cost microcontroller are shown to validate the operation of the current and voltage controllers.

EMI investigation yield by single-phase PFC pre-regulators

This paper investigates the problem of electromagnetic interference (EMI) generated into power converters used to correct the power factor (PFC). The topologies discussed in this paper are the boost converter, interleaved boost and dual boost. The paths traveled by differential mode (DM) noise and common mode (CM) noise are illustrated. An analysis of the inductor parasitic capacitance impact over the conducted noise is realized. All converters were designed in a way that the total harmonic distortion (THD) of the input current be the same, in order to use the same input filter. The EMI filter designed to comply with the EMI standards and experimental results with filter are also shown.

Integrated methodology design to improve the efficiency and reduce volume of the CCM PFC boost converters with pre-sizing settings

This paper presents an optimization design methodology for CCM PFC Boost converters with volume and efficiency objectives. The optimization methodology, achieved by mathematical interactions, is based on the concept of the converter integrated design, in other words, all the main physical converter components are designed simultaneously in the function of a pair of overall variables. The integrated design provides for the reduction of cost and time of the project design of the system and also gives complete and matched solutions with the objective of the proposed optimization. The proposed methodology is evaluated with a PFC Boost converter including an input EMI filter (1000-W output power, 400-VDC output voltage and 220-VAC input voltage). In this case study, three different magnetic materials are used in both inductors designs (Boost and EMI filter) in order to demonstrate how technology affects the volume and efficiency results. To confirm the theoretical analysis that was carried out, the experimental mechanical, electrical and thermal measurements are presented.

Efficiency optimization of DC/DC boost converter applied to the photovoltaic system

This work has as objective to maximize the efficiency of the DC/DC boost converter, used to track the maximum power of a PV system implemented by three panels, connected in series, with a total power of 600 W. The maximization is based on the selection of the magnetic material and of the operating point (Δi @ fs) that results in the best weighted average efficiency. Losses in the capacitors, semiconductors and magnetic devices are considered. Experimental results are presented to validate the simulated results obtained, as well as results of the efficiency of the boost converter. There different points will be presented to prove that operating point selected is the best among them.

Different optimum designs investigation of DC/DC boost converter applied to the photovoltaic system

This paper investigates different optimum designs of DC/DC boost converters applied to photovoltaic systems. The main goal of this work is to improve the total efficiency of a boost converter used to track the maximum power of a PV system, which is formed by three panels, connected in series yielding a total power of 600 W. Efficiency improvement is achieved by means of the selection of an operating point for the converter (Δi @ fs) and choosing the magnetic core and conductor diameter, which provide minimal losses. The losses in capacitors, semiconductors and magnetics are evaluated forall load range. After that, it is obtained the efficiency in 5%, 10%, 25%, 50%, 75% and 100% of nominal power in order to calculate the weighted average efficiency. From this evaluation, the operation point and the magnetic material that will result in the best efficiency are selected. Experimental results are presented to validate the simulated results obtained, as well as results of the total efficiency of the boost converter. Three different configurations will be presented to prove that the operating point and the magnetic core selected is the best among them. A discussion of the results is presented, where alternatives to improve efficiency throughout the power range are analyzed.

Comparison between full-bridge-forward converter and DAB converter

This paper analyzes and compares the dual active bridge (DAB) converter and the full-bridge-forward integrated DC-DC converter when applied to a microgrid energy storage bidirectional system that demands high power flow at the discharging operation mode and low power flow at the charging operation mode. The phase-shift modulation (PSM) is generally applied on the DAB converter, but it presents practical limitations, such as maximum and minimum phase-shift angle restrictions. In order to obtain a wide power variation range on the discharging operation mode, a hybrid modulation scheme can be applied. On the other hand, the full-bridge-forward DC-DC converter is also an alternative, which is specifically designed for different power level bidirectional processes and therefore presents low number of active devices. Theoretical analysis and experimental results of both converters are presented.

Analysis of different designs for the boost converter applied to PV systems

This paper presents an analysis of different designs of DC/DC boost converter applied to photovoltaic systems. Different objectives are evaluated and the impact over the energetic efficiency, volume, and energy losses resulting of the boost converter are investigated. The used design methodology selects the best solution through a unique objective function and its obtained weights of importance of its (single or multi) criteria: i. Energetic efficiency; ii. Volume; iii. Energetic efficiency and volume. It is defined the selection way of the best solution by importance attributed to energetic efficiency and volume. The methodology will select the input current ripple of boost inductor, the switching frequency, the magnetic materials, number of stacked cores, winding cross section, the capacitors part number, heat sink part number, and semiconductors part numbers which maximize the objective function. The best solution provided a reduction of 50.7 % when compared to the higher volume solution, maintaining the energy efficiency nearly 98.18 %. Experimental results are presented in order to validate the methodology.