Doctors Projects 2011

Adriano Ruseler

Multilevel Modular Converter integrated with the Load

Features:
•    Medium Voltage Motor Drive Application
•    Strictly Modular Construction  (identical sub modules)
•    No Zero sequence current.
•    Redundant operation capability after semiconductor failure
•    Multilevel voltage ( High frequency phase delay between modules in the same arm )
•    Low cost semiconductors (Low rated semiconductor voltage)
•    High frequency modulation ( Fast dynamics behavior )
•    Suitability for direct motor integration
•    Low voltage slew rate.

 


Antonio José Bento Bottion

Modular Bi-Directional DC-DC Conversion for High Voltage and High Power

Figure 2 – Modular Bi-Directional DC-DC Conversion for High Voltage and High Power.

Advantages:
•    Makes possible the energy transfer between two DC bus;
•    Modular system with  the input-series and output-series on each module;
•    Modules with low voltage switch;
•    Easy maintenance and protection.

 


Eduardo Valmir de Souza

Bidirectional Current-Fed Flyback-Push-Pull DC-DC Converter

Figure 3 – Proposed Bidirectional Current-Fed Flyback-Push-Pull dc-dc converter and adopted conventions.

Advantages:
•    Low switches current stress;
•    Protection against transformer core saturation in both of power flow directions;
•    Common reference command signal  of switches from same side;
•    Possibility of synchronous rectification.

 

Table 1 – Prototype spectification.

Figure 4 – Experimental waveforms in Boosts->p operation mode.

Figura 5 – Formas de ondas experimentais no modo de operação Boost s->p.


Eloi Agostini Junior

Three-Phase Three-Level ZVS PWM DC-DC Converter

Figure 6 – Proposed three-phase three-level ZVS PWM DC-DC converter.

Main features:
•    Switch voltage stresses are half of input voltage value;
•    Possibility of achieving ZVS for all converter switches;
•    Use of a three-phase high-frequency transformer for isolation.
•    Output stage has voltage source characteristic;
•    Symmetric PWM.


Table 2 – Prototype specifications.

Figure 7 – Output characteristic.

Figure 8 – Prototype picture.


Gabriel Tibola

A Single-Stage Three-Phase AC-DC Converter with High-Frequency Isolation Based on the DC-DC SEPIC Converter Operating in Discontinuous Conduction Mode

Figure 9 – Proposed three-phase rectifier structure power stage.

Abstract:
In order to reduce the control input current complexity and the current sensor employment, this work proposes a single-stage three-phase rectifier unit, with high-frequency isolation and regulated output voltage, based on the SEPIC DC-DC converter operating in discontinuous conduction mode (DCM), which provides unity power factor, without the use of any current sensor and currents loop control.

Advantages:

  • Power factor correction;
  • Regulated output voltage;
  • Single stage;
  • High frequency isolation;
  • Operation with step-up and step-down characteristic;
  • Only three active switches;
  • Absence of any current sensor and currents control loop;
  • The input inductors might be allocated on the AC or DC converter side, but there are advantages on applying them to the AC side, since the generator inductances or, even, the grid line inductances can be exploited;
  • Possibility of coupling the input inductors when using phase shifted carrier.

Principais Resultados Experimentais:

Table 3 – Specifications

Figure 10 – Picture of the 4kW three-phase SEPIC rectifier prototype.

Figure 11 –Experimental waveforms: switch base-emitter voltage (50V/div), output diodes current sum (20A/div), output diodes current (20A/div).

Figure 12 – Experimental waveforms: (A) input current for each phase (5A/div); (B) high frequency input current detail  (5A/div); (C) input voltage (200V/div), input current (10A/div); (D) input current harmonic spectrum.


Gleyson Luiz Piazza

Zeta-Sepic Inverter

Figure 13 – Power Stage of  Zeta-Sepic inverter.

Features:

  • Possibility of operating at peak AC voltage higher or lower than the bus voltage;
  • It does not require the use of transformer between the terminals of the load when the DC-AC converter operated in the step-up voltage mode;

 

Figure 14 – Voltage gain for Buck and Zeta-Sepic inverters.

Figure 15 – Output voltage and current in inductor Lf.


Moisés Carlos Tanca Villanueva

A High Step-up High Efficiency Non-Isolated DC-DC Converter

Figure 16 – Proposed topology of high step-up converter based on the stacking of a modified commutation cell.

Table 7 – Prototype Specification.

Feature of Prototype:

  • The proposed topology based on the stacking of a modified commutation cell is studied and built to distribute the voltage stress in its components.
  • The voltage across the power semiconductor is very lower than the output voltage of high step-up gain converter.
  • The reduction of voltage across power MOSFETs, diodes and capacitors allows the utilization of power semiconductors with lower conduction and commutation losses.
  • Applications as the front end stage in the back-up energy system for uninterruptable power supply.
  • Non-isolated applications where a high voltage gain is necessary as vehicles system and renewable electric power processing systems.

 

Figure 18 – Main experimental waveform