Valdeir J. Farias

An optimal lossless commutation quadratic PWM Boost converter

This paper presents a PWM boost power converter, where the DC voltage conversion ratio has a quadratic dependence on the duty cycle, providing a large voltage step up (from 24 V to 160 V). By introducing two resonant networks, soft switching is achieved, providing highly efficient operating conditions for a wide load range at high switching frequencies.

A new boost converter using a nondissipative snubber

This work presents a new PWM boost converter with nondissipative snubber. This proposed approach allows building a converter with high frequency operation. The boost converter proposed allows to join the characteristics of the nondissipative switching with the characteristics of the PWM switching, the converter using this association works with constant frequency. This paper presents the complete operating principles, theoretical analysis, relevant equations, simulation and experimental results.

An unity high power factor power supply rectifier using a PWM AC/DC full bridge soft-switching

This paper proposes an improvement of an isolated unity-power-factor rectifier AC/DC PWM based on a PWM full bridge converter using a commutation cell. This converter operates using soft switching technique. It presents high power factor, full control of the output dc voltage and high-frequency line filter inductor and insulation transformer. It is based in an auxiliary voltage source that feeds the resonant circuit, charging a capacitor that provides the condition for zero voltage switching (ZVS) of the main switches. This paper presents a detailed analysis of the topology, which is then verified by means of complete theoretical analysis, operating principles and simulation results are presented to show the feasibility of proposed power factor correction converter. This work presents simulations and experimental results of a prototype converter operating at 100 kHz.

Modeling and control of a single-stage current source inverter with amplified sinusoidal output voltage

Alternative energy sources has been attracting great interest in the area of static converter development. This fact is related to issues like sustainability and the world environment, which is contributing to viability of this type of energy source. The main challenge is to develop systems that transform this DC energy in AC. Within this subject, this paper focuses the establishment of a new control strategy applied to a step-down/step-up single-stage inverter with imposed waveforms of input inductor current and output voltage. The proposed control strategy provides high voltage gain without using high frequency transformer, which contributes to weigh and size reduction of the proposed DC-AC converter structure. Theoretical analysis are presented and corroborated by experimental results of a 180W laboratory prototype fed by a fuel cell.

Proposal for preprogrammed control applied to a current-sensorless PFC boost converter

The development of front-end converters for power factor correction and DC link voltage control of power electronics converters such as, UPS, Inverters, and Switched Power Supplies, has been attracting great interest from the scientific community that works toward the achievements of cost reduction, high efficiency, and reliability. In this context, this paper proposes a microprocessed control technique for sinusoidal input line current imposition in front-end ac-dc converters. This gave rise to an innovative sensorless boost converter, named in this work as PFC-Boost-CSL. The proposed method is based on experimental acquisition of gate-drive signal sequences for different load conditions. These signals correspond to a complete cycle of the AC input voltage and are recorded in the microcontroller memory in order to be reproduced when used in a boost converter without current sensor. In the operation of PFC-Boost-CSL, a suitable switching sequence is sent to drive the power switch in order to minimize output voltage error and maintain a sinusoidal input current. Aiming to prove the proposed control concept, a 600W PFC-Boost-CSL prototype was built and analyzed in laboratory and the main experimental results are presented herein.

Current-sensorless PFC Boost converter with preprogrammed control strategy

The development of front-end converters for power factor correction and DC link voltage control of power electronics converters such as, UPS, Inverters, and Switched Power Supplies, has been attracting great interest from the scientific community that works toward the achievements of cost reduction, high efficiency, and reliability. In this context, this paper proposes an innovative microprocessed control technique for sinusoidal input line current imposition in front-end sensorless Boost converters, named in this work as PFC-BOOST-CSL. The proposed method is based on experimental acquisition of gate-drive signal sequences for different load conditions. These signals correspond to a complete cycle of the AC input voltage and are recorded in the microcontroller memory in order to be reproduced when used in a Boost converter without current sensor. In the operation of PFC-BOOST-CSL, a suitable switching sequence is sent to drive the power switch in order to minimize output voltage error and maintain a sinusoidal input current. Aiming to prove the proposed digital control concept, a 600W PFC-BOOST-CSL prototype was built and analyzed in laboratory and the main experimental results are presented herein.

An electronic ballast employing a boost half-bridge topology

This paper proposes a new electronic ballast employing a boost half-bridge topology. A boost converter is used to control the input power factor, and a half-bridge topology is used to drive the fluorescent lamp. Both stages are associated in order to simplify the design procedure, as the proposed scheme represents a simple and robust converter. A comparison between this arrangement and another one previously proposed is still presented.

True zero current turn-on and turn-off converter family: Analysis, simulation and experimental results

This paper presents a new non dissipative commutation cell applied to a buck converter. The commutation cell is composed by one main switch and two auxiliary switches operating with zero current turn on and off. This new soft-commutation cell presents the following advantages: soft-commutation for a wide load ratio, better current distribution among semiconductors, besides, the main switch must be rated at nominal load current. Therefore, a new true zero turn on and off converter family capable of operating in high frequency could be achieved, providing high power density and efficiency.

A lossless commutation PWM full-bridge DC-DC converter using phase shift control

This paper presents a self resonant PWM full-bridge DC-DC converter using phase shift control. This approach is based in the principle of the self-resonance, that is: an auxiliary voltage source feeds the resonant circuit, charging the capacitor which provides the condition for the zero voltage switching (ZVS) of the main switches. The proposed approach allows building a converter with high power density and high operation efficiency capable of operating over all the load range. The operating principle, theoretical analysis, simulation and experimental results are presented.

A lossless commutation pulse width modulated converter by using a resonant disconnecting circuit

The authors describe a lossless commutation buck pulse-width-modulated converter that uses a resonant disconnecting circuit (buck-LC-PWM-RDC). The operation principle, design-oriented analysis, numerical simulation, and experimental results are presented. The topology presents a novel working mode. This is obtained by using a resonant commutation cell composed of three switches, two capacitors, and two inductors. The three switches commutate under zero current, zero voltage, and zero current, respectively. The most important property of the circuit is the ability to regulate output power and voltage by pulse-width-modulation, with constant operating frequency, without load limitation, and without sacrificing the lossless commutation. As a consequence, the time response is improved, and the design procedure and implementation are facilitated.<<ETX>>