Doctorate Students' Researches at INEP - 2008

Alceu André Badin
Carlos Henrique Illa Font
Edward Leonardo Fuentealba Vidal
Hugo Rolando Estofanero Larico
Mauro Tavares Peraça
Romero Leandro Andersen
Romeu Hausmann
Telles Brunelli Lazarin

AlceuAndré Badin

Unity Power Factor Three-phase Rectifier Based on the Three-Phase/Two-Phase Transformers

Figure 1 - Three-phase Buck-Serie Rectifier.

Figure 2 - Experimental results.

The study of Three-Phase Buck Rectifiers results in three new topologies with advantages below :

Only two active switches;
Source current characteristic output;
No inrush circuit;
Low current on the output capacitors.

CarlosHenrique Illa Font

Unity Power Factor Bidirectional Three-Phase Hybrid Rectifier

Figure 1 - Proposed Hybrid Rectifier.

Figure 2 – Laboratory Prototype and Specifications.

Rms Mains Line Voltage

380V

Mains Frequency

60Hz

Output Voltage

700V

Output Power

20kW

Switching Frequency

10kHz

Figure 3 – Input Currents and Output Voltage.

Figure 4 - Experimental Curves.

Unity power factor;
Output voltage control;
Bidirectional power flow;
High power applications;
Competitive solution for AC Drives.

Edward Fuentealba Vidal

Single and Three Phase Rectifier with Diferential Load Controlled by Sliding Regime: Analysis, Project and Implementation

Three-Phase Topology Proposed to AC-DC Reversible Converter:

Figure 1 - Three-Phase model proposed by Fuentealba and Barbi.

Figure 2 - Subsystem.

Figure 3 - Operation as Inverter.

Figure 4 - Operation as Rectifier.

It operates, as rectifier or inverter, utilizing only one cell of conventional switching.
The output voltage can be lower, equal or greater than the input voltage peak.
It is bidirectional in current.
The converter is able to maintain the input current, iLac, very close to the imposed sine reference (in phase with the input voltage), achieving a power factor close to the unit.
Two topologies can get to reduce of THD of the input current.

Hugo Rolando Estofanero Larico

Family of Trifasic DC-DC converters

Figure 1 - Current-fed Push-Pull Trifasic DC-DC Converter with Three Inductors.

Characteristics:
Duty-cycle operation: 2/3<D< 1
Low ripple current in the input
All energy is transfer through trifasic transformer
Reduced volume of magnetic elements

Figure 2 - Current-fed Push-Pull Trifasic DC-DC Converter with Three coupled Inductors.

Characteristics:
Duty-cycle operation: 0<D<1
Partial energy is transfer through trifasic transformer for duty-cycle: 0<D<2/3
Reduced volume of magnetic elements Simulation Results

Parameter

Value

Input voltage (Ei)

48V

Switching Frequency (fs)

30kHz

Magnetization inductance of the inductor (Lfm)

500mH

Capacitance of the output filtering (Co)

22 mF

Load resistor (Ro)

5 W

Duty Cycle(D)

0.25

Figure 3 - Magnetization current and voltage in the coupled-inductor Lf1.

Figure 4 - Voltage and current output and current input in the converter.

Mauro Tavares Peraça

Converters using four-state commutation cell

The four-state commutation cell presents the following advantages:
distribution of the currents among the phases;
reduction in the conduction losses switches;
frequency of filters are three times the switching frequency;
ripple reduction;
reduction of size filters;
improve transient response.

Figure 1- Four-state commutation cell.

Figure 2 - Proposed half-bridge inverter.

Figure 3 - Experimental Results.

The advantages of the four-level half-bridge inverter:
the output voltage presents four levels;
the output frequency is three times the switching frequency;
reduction of size filters;
a significant reduction in the harmonic content.