Paulo P. Praca

Interleaved-Boost Converter With High Voltage Gain

This paper presents an interleaved-boost converter, magnetically coupled to a voltage-doubler circuit, which provides a voltage gain far higher than that of the conventional boost topology. Besides, this converter has low-voltage stress across the switches, natural-voltage balancing between output capacitors, low-input current ripple, and magnetic components operating with the double of switching frequency. These features make this converter suitable to applications where a large voltage step-up is demanded, such as grid-connected systems based on battery storage, renewable energies, and uninterruptible power system applications. Operation principle, main equations, theoretical waveforms, control strategy, dynamic modeling, and digital implementation are provided. Experimental results are also presented validating the proposed topology.

High-Voltage Gain Boost Converter Based on Three-State Commutation Cell for Battery Charging Using PV Panels in a Single Conversion Stage

This paper presents a novel high-voltage gain boost converter topology based on the three-state commutation cell for battery charging using PV panels and a reduced number of conversion stages. The presented converter operates in zero-voltage switching (ZVS) mode for all switches. By using the new concept of single-stage approaches, the converter can generate a dc bus with a battery bank or a photovoltaic panel array, allowing the simultaneous charge of the batteries according to the radiation level. The operation principle, design specifications, and experimental results from a 500-W prototype are presented in order to validate the proposed structure.

Single stage high voltage gain boost converter with voltage Multiplier Cells for battery charging using photovoltaic panels

This paper presents a non-isolated high frequency DC-DC converter, which integrates a battery charger, photovoltaic panels, and a high voltage gain boost converter in a single conversion stage with soft-switching characteristic. The proposed topology uses voltage Multiplier Cells (MCs), leading do high voltage step-up. Also, the bidirectional behavior admits the DC bus to be generated via battery bank, or photovoltaic panels, or both, depending on the insulation condition. At last, experimental results validate the proposed topology, proving its effectiveness.

Five-level hybrid converter based on a Half-Bridge/ANPC cell

This work presents a novel five-level hybrid Half-Bridge/ANPC multilevel inverter. Along with the switching states possibilities, employed modulation techniques, conduction losses analysis, and simulation results from a three-phase topology, it is presented the experimental results from a monophasic structure, operating with 1020Hz switching frequency, output frequency of 60Hz, phase output voltage of 220Vrms, output power of 2.3kW and power factor of 0.92. From the presented results, it can be noticed the reduced losses and better harmonic content.

A two-stage AC/DC SST based on modular multilevel converterfeasible to AC railway systems

This paper proposes the use of the modular multilevel converter (MMC) for ac-dc conversion using medium frequency transformers in a two-stage topology with unidirectional switches. The losses analysis of the propose converter are presented with a comparative study among others two topology well know in the literature for traction applications. The basic description of the topology and some simulation results are presented, followed by a comparative losses result.

A bidirectional single stage AC-DC converter with high frequency isolation feasible to DC distributed power systems

This paper proposes a single-phase bidirectional ac-dc converter feasible to dc distributed power systems. The topology provides galvanic isolation and is able to protect the system during short-circuits occurrence in the load side. The power factor control in the ac side is performed by the duty cycle variation in the primary bridge. It is supposed to regulate the dc bus voltage even during voltage dips and short-circuits. The secondary side bridge is driven with constant duty cycle and the power flow is controlled by the variation of the phase shift angle between the two bridges. The basic equations are shown and the simulation results are presented and discussed.

High voltage gain boost converter battery charger applied to PV systems

This paper presents a soft-switching (ZVS) boost converter integrated in such a way to obtain, in a single conversion stage, the maximum energy extraction from photovoltaic panels, battery charging and discharging dynamic control, and high voltage step-up to the inverter DC bus, also operating with soft-switching capability. In order to verify its effectiveness, experimental results from this converter are presented. Theoretical analysis, operation principle and topology details are also presented and studied. High voltage gain, low switching stress, small switching losses, and high efficiency are expected from this topology.

High voltage gain single stage DC-DC converter based on three-state commutation cell

This paper presents a high voltage gain single stage DC-DC converter based on the three-state commutation cell. The presented converter operates with soft-switching ZVS mode for all switches. The operation principle, project specifications, and experimental results from a 500W prototype are presented in order to validate the proposed structure. The results show de soft switch commutation, reduced stress and high efficiency (over 94%).

Comparative analisys of performance for single-phase AC-DC converters using FPGA for UPS applications

This paper presents a comparative analysis of performance for three single phase AC-DC converters for UPS applications. The analyzed converters are the conventional three-level converter, the five-level interleaved converter, and the T type five-level converter. Such converters are used as input stage of UPS and have as common characteristic: power factor correction, digital control using FPGA and connection between input power supply and converter output enabling the use of UPS inverter and bypass. All the converters have the same design parameters, and the project specifications. The control system used to perform the PFC is based on OCC technique implemented by FPGA. The analyzed topologies comparison parameters are: current semiconductors stresses, power factor, total harmonic distortion, magnetic volume and weight, efficiency and dynamics response.

Carrier-based PWM modulation for THD and losses reduction on multilevel inverters

This paper presents an adapted carrier-based PWM modulation technique to be applied on both NPC and FC structures of multilevel inverters. The proposed modulation leads to an improved performance of the output voltage THD and also reduces the total loss dissipation across the semiconductors devices, when compared to other conventional carrier-based PWM modulation techniques, such as PSPWM and LSPWM. The effectiveness of the proposed technique is demonstrated through experimental results of a three-phase, three-level, 6kW prototype.