René P. T. Bascopé

Step-up converter with high voltage gain employing three-state switching cell and voltage multiplier

This work proposes a new non-isolated DC-DC converter with high voltage gain using a three-state switching cell and voltage multiplier stages based on capacitors. The value of the gain can be modified depending on the requirements of the application by means of the number of multiplier stages and the duty cycle. The proposed converter can be employed in renewable energy systems where commonly low input voltages (12 Vdc to 48 Vdc) are involved or in uninterrupted power supply (UPS) systems in order to avoid the necessity of a step-up transformer. One first advantage of the proposed solution is the reduced voltage stress across the active switches that is lower than half of the output voltage, what allows the use of MOSFETs with lower drain-to-source resistance. Moreover, by employing the three-state switching cell, the size of the inductor is reduced because the operating frequency of the inductor is double of the switching frequency. The current share between the active switches allows further reduction of the conduction losses. A prototype was built for an input voltage range of 30-45 V, 400 V output voltage and 250 W output power. The operation was evaluated and the experimental waveforms and experimental efficiency curves as a function of the output power are presented.

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

High voltage gain boost converter based on three-state switching cell and voltage multipliers

A new type of non-isolated step-up converter with high voltage gain is proposed on this work. It is suitable for applications with a high voltage gain between the input and the output stages. In this converter, the output to input voltage ratio, for a given duty cycle, can be raised by adding voltage multiplier stages of capacitors (mc).The theoretical and experimental results it will be present in this paper considering two configurations (mc=2) and (mc=3).An important feature of this converter is the lower blocking voltage across the controlled switches compared to similar circuits, which allows the utilization of low voltage MOSFETs switches. In order to verify the feasibility of the proposed topology, the principle of operation, theoretical analysis, and experimental waveforms are shown for a 1 kW prototype.

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.

Multi-state commutation cells to increase current capacity of multi-level inverters

This paper presents four generalized multi-state switching cells to increase current capacity, output voltage levels, and power processing of multi-level inverters. Such cells are named of multi-level multi-state switching cell (ML-MSSC), neutral point clamped multi-state switching cell (NPC-MSSC), flying capacitor multi-state switching cell (FC-MSSC), and H-bridge multi-state switching cell (HB-MSSC). Using the multi-state switching cells, single phase, three phase, and polyphase inverters can be generated for high power and high input bus voltage applications. In order to validate the theoretical assumptions, a particular application that consists of a five-level NPC inverter is studied, designed, and implemented in laboratory. Experimental results from a 10kW prototype are then obtained and relevant issues are discussed.

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.

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.

Comparative evaluation of three single-phase NPC inverters

In this paper is presented a comparative evaluation in steady-state of three single-phase NPC multilevel inverters. The first is a five-level neutral point clamped (NPC) inverter based on multi-stage switching cell (MSSC); the second is also a five-level neutral point clamped (NPC) inverter based on interleaved cell (IC); and the third is a three-level neutral point clamped (NPC) inverter based on paralleled cell (PC). For this comparative purpose, the switching frequency is constant and the evaluated parameters are the volume of the heatsinks and the passive components, the total harmonic distortion (THD) of the output voltage, the power density and efficiency of each topology. Theoretical analyses, as well as simulation and experimental results obtained from 5kW prototype are 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.