Master Degree Students' Researches at INEP - 2008

Gabriel Tibola
Gierri Waltrich
Gláucio Roberto Tessmer Hax
Gleyson Luiz Piazza
Gustavo Ceretta Flores
Mateus Costa Maccarini
Rodrigo da Silva

Gabriel Tibola

Small Wind System with Maximum Power Point Tracker

1 - Main Characteristics:
Three Blades Horizontal-Axis Rotor with fixed pitch;
Permanent Magnet Synchrounous Generator with Axial Flux.

2 - Objectives:
Conventional System Valuation to Battery Charging Applications;
Attainment of a Wind System Model to Simulation;
Study of the Static Power Converters to Optimize the System;
Control Strategy for Maximum Power Operation without Mechanical Sensors;
Comparison between the Conventional System and Suggested one.

3 - Basis:
This study is based on the calculated maximum electric power versus rectified DC voltage curve to obtain a maximum power output at a certain wind speed from duty cycle disturbance in the DC-DC converter.

Figure 1- Representation of Classic System.

Figure 2- Wind System Model and Conventional System Simulation Circuit.

Figure 3–Main Curves of the Conventional System (Wind Speed = 10 m/s).

Figure 4- Suggested System.

Figure 5–Buck Converter and Control Strategy.

Figure 6- Converter Circuit Simulation to Maximum Power Point Tracker.

Figure 7- Main Curves of the Considered System (Wind Speed = 10 m/s).

Gierri Waltrich

Three-Phase Multilevel Inverter Structure with Nine Levels of Voltage

1 - Goal of  work:study a model of three-phase multilevel inverter structure with nine levels of voltage.

2 - Proposed multilevel inverter: the structure was based on the classic inverter.

Figure 1 – a) Classic Inverter; b) Change in classic inverter; c) Proposed structure.


Figure 2 – Multilevel inverter structure with n levels of voltage.

Table 1 –Specification of prototype.


Figure 3 – Phase multilevel inverter structure with nine levels of voltage in the load.

3 - Simulation Results:

Figure 4 - Voltage and current in the load.


Figure 5 - Command of the modules inverters switches 1 and 2.

Gláucio Roberto T. Hax

UPS of Long Autonomy Using Fuel Cell

1 - Objective
To make a system that connecting a UPS with a Fuel Cell, making this UPS with bigger autonomy that the UPS with batteries.

Figure 1 - structure with interconnection of searched system.

Structure with Forward Converter of Interconection

Table 1 - Specification of Converter.


Figure 2- Converter of interconnection with fuel cell and UPS.

Gleyson Luiz Piazza

Implementation of a Source for Laser Ray

1 - Objectives of the Work:
Implementation of a high-voltage source for drive of a ray-laser pipe.

2 – Structure:
The project uses the parallel resonant half-bridge converter with output in source of voltage, modulated by the pulse width and frequency of switching operating with less than the frequency of resonance. The system uses five transformers and five voltage doublers to feed the discharge pipe, as shown in figure 1. The electric characteristics of the laser are approximated by the circuit of figure 2.

Figure 1- Structure used.


Figure 2 - Circuit equivalent for the laser.


Figure 3- Approach curve of the laser.

Specifications of the structure: Input voltage of the half-bridge converter 155 V;
Voltage of excitement of laser ray 50 kV;
Switching of frequency 45 kHz;
Power of source 700 W;
Maximum power of beam 100 W;

3 – Simulations: AFigure 4 presents the result of simulation for the converter feeding the discharge pipe.

Figure 4 - Current and voltage output for the laser.

The figure 5 and figure 6 presents the experimental results for the converter operating without load and with resistive load, respectively. They are observed the current in the inductor and the voltage in the resonant capacitor.

Figure 5 - Voltage in the capacitor and current in the resonant inductor without load.


Figure 6- Voltage in the capacitor and current in the resonant inductor for resistive load.

Gustavo Ceretta Flores

Contribution to Study of Neutral-Point Clamped Five-Level Inverter

Figure 1 - Five-level inverter with and without series conected diode.


Figure 2 - 5L-NPC inverter with stray inductances.


Figure 3- Overvoltage on diode during the commutation process from Dg to S1 and Overvoltage on IGBT during the commutation process from S1 to Dg.

Mateus Costa Maccarini

Single-phase Inverter Applied at Connection of a Wind Power Generator to the Electric Grid

1 - Objectives of the Work:
Connection of a wind power generator, of small size, to the commercial electric distribution grid.

2 - Chosen Structure:
Full bridge single-phase inverter with an elevator voltage transformer in the output.

2.1 - Specifications of the Structure:
1kW of output power;
100V of voltage in the DC link;
220V of rms voltage in the output;
Three level pulse width modulation.

Figure 1 - Single-phase inverter.

3 – Results of First Simulations

Figure 2- Simulated circuit.

50% positive load step:

Figure 3- Simulation results.

Rodrigo da Silva

Multi-Level Inverters with Multi-Winding Transformers

Figure 1- Main Estruture.Goal: High frequency elimination.

Figure 2 - Modulation Strategy.

Figure 3- Simulation Results.