Carlos Elmano de Alencar e Silva

Proposal of a New High Step-Up Converter for UPS Applications

This paper proposes the use of a voltage doubler rectifier as the output stage of an interleaved boost converter with coupled inductors. The obtained voltage gain is twice that of traditional boost converters due to the doubler stage, as coupled inductors provide additional voltage gain, although voltage stress across the switches is not increased. The resulting topology is adequate for battery sourced systems which require low current ripple and high voltage gain e.g. UPSs and audio amplifiers. Additionally, it can be used to obtain symmetrical power supply. Theoretical analysis and experimental results from a 1 kW prototype are shown

A variable speed wind energy conversion system connected to the grid for small wind generator

The wind energy system presented in this paper uses a permanent magnet generator connected to a three- phase semi-controlled rectifier. Although an acceptable THD and power factor result, the proposed converter is simple, cheaper, and robust. Additionally, a single-phase PWM inverter is also employed in the grid connection. The inverter uses a double hysteresis in the control of the current injected in the grid, what implies reduced switching losses. Analysis and partial experimental results are presented for a 5 kW prototype. At the final version of this paper, a more detailed theoretical analysis, simulation results, as well as experimental results at rated power are supposed to be presented.

Analysis, Design, and Experimentation of a Double Forward Converter With Soft Switching Characteristics for All Switches

The study of a topology resulting from the combination of two forward structures attached to a single transformer core is presented in this paper, as a dual active bridge converter is obtained. In order to reduce the switching losses and the electromagnetic interference, a soft commutation cell, which provides zero-voltage commutation of the main switches for the entire load range, is implemented. Besides, the auxiliary switches are zero-current turned on and zero-current, zero-voltage turned off. This converter reduces the voltage over the main switches to half of the input voltage, employing only four switches and an additional transformer winding when compared to the full-bridge converter. The analysis of the circuit is carried out, and experimental results obtained from a prototype are also presented to support the theoretical assumptions.

A novel three-phase rectifier with high power factor for wind energy conversion systems

In this paper it is proposed a new topology of three-phase controlled rectifier feasible for high power wind energy conversion systems (WECS). This rectifier is based on the bridgeless rectifier, uses six wires of the generator, and allows the operation with high power factor, increasing the generator efficiency. One cycle control (OCC), which avoids the need of sinusoidal reference signals, was used in the rectifier control. This study is then concerned with the operation principle and experimental results obtained from a 5 kVA prototype.

Three-phase power factor correction rectifier applied to wind energy conversion systems

This paper proposes a topology of three-phase controlled rectifier feasible for small wind energy conversion systems. This rectifier uses six wires of the generator and allows for the operation with high power factor, increasing the generator efficiency. One Cycle Control (OCC) was used in the rectifier control. This study is concerned with the operating principle, a design example, and some simulation and experimental results for a 5 kW prototype.

ZVS bidirectional isolated three-phase DC-DC converter with dual phase-shift and variable duty cycle

This paper presents the analysis, design, and simulation results for a ZVS bidirectional isolated three-phase DC-DC converter with dual phase-shift and variable duty cycle. The topology uses three single H-bridges in the primary side and a three-phase inverter in the secondary side. The isolation is ensured by using three single-phase transformers connected in open delta-wye configuration. Variation of both phase shift angles between single H-bridge legs and/or primary and secondary side allows the power delivery control. This additional flexibility allows the system to maintain a low reactive power flow. The variable duty cycle is used to ensure a constant voltage bus and ZVS soft switching operation. A detailed analysis is presented considering a model based on fundamental components. Simulations for converter are performed to validate the model used.

On the study of wind energy conversion system applied to battery charching using multiblade turbines

This paper presents control system design of a small size wind generation system for battery charging using a multiblade wind turbine. A boost converter is used to regulate the battery bank voltage. Thus, an MPPT algorithm can be implemented as well as the reduction of the mechanical speed can be performed in order to avoid a battery overcharging or overcurrent. The system overview and modeling are presented including characteristics of wind turbine, generator, batteries, power converter, control system, and supervisory system. A simulation of the system is performed using MATLAB/SIMULINK software to obtain the MPPT points. Experimental results for the complete system are also presented.

A DC-AC Converter with High Frequency Isolation

This work presents the analysis, design, simulation and experimental development of a single-phase inverter with high frequency transformer isolation and for a wide input voltage range. The high frequency input current ripple is mitigated by the use of a small input LC filter, and the low frequency current component injected by the inverter is attenuated by the voltage loop controller. The proposed topology can be used in dc voltage- sourced applications such as renewable energy and battery systems.

Three-stage static power converter for battery charging feasible to small wind energy conversion systems

This paper presents the analysis, design, simulation, and experimental results for a three-stage static power converter for battery charging feasible to small wind energy conversion systems (SWECS). The system employs a boost converter cascaded with a Graetz bridge, what allows the implementation of a Maximum Power Point Tracker (MPPT) and the reduction of the mechanical speed under overvoltage conditions across the batteries. Besides, a buck converter is connected in series with the boost stage to ensure a constant voltage bus between the aforementioned topologies. Thus, it is possible to extract the maximum power over the entire wind speed range, and battery charging can be realized through conventional techniques. The complete design of the proposed battery charger including power, control, and supervisory circuits are presented and developed, considering a 300 W system, with the possibility of charging battery banks rated at 12 V or 24 V. Simulation results are presented to prove the existence of maximum power points in the wind generator. Finally, the experimental results of the developed prototype required to validate the functionality of the proposed study are presented and discussed.

Three-phase voltage doubler rectifier based on three-state switching cell for Uninterruptible Power Supply applications using FPGA

This paper presents a three-phase voltage doubler rectifier based on three-state switching cells for Uninterruptible Power Supply (UPS) applications using FPGA. Its main features are: high power factor, reduced conduction losses, weight and volume, simple control strategy based on One-cycle Control (OCC), and connection between input and output enabling the use of inverter and bypass. A theoretical analysis, simulation results and preliminaries experimental results from a 9 kW development stage lab model are presented.