Gustavo B. Lima

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.

Proposal of a hybrid rectifier structure with HPF and low THD suitable for front-end trolleybuses systems supplied by AC distribution networks

This paper presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency.

A novel single-phase HPF hybrid rectifier suitable for front-end trolleybus systems

This paper proposal presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency. The proposed structure is composed by an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of composing the input line current waveform assuring high power factor (HPF) and low THDI, as well as ordinary front-end converter. However, the power rating of the switched converter is about 34% of the total output power, assuring robustness and reliability. Therefore, the proposed structure was named single-phase HPF hybrid rectifier. A prototype rated at 15 kW was developed and analyzed in laboratory. It was found that the input line current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis, the PWM control strategy, and experimental results of a 15 kW prototype are also presented in this paper.

Renewable uninterruptible power supply system deploying a single-phase front-end converter with integrated PFC and DC-DC functions

This paper presents the development of a single-phase online Uninterruptable Power Supply (UPS) system using a HPF front-end Boost converter with integrated Power Factor Correction (PFC) and DC-DC functions and an ordinary Full-Bridge as the single-phase output inverter. Besides the front-end stage with integrated PFC and DC-DC functions, the main feature of the proposed solution is the use a Proton Exchange Membrane Fuel Cell (PEMFC) as an energy storage system in substitution to batteries banks, eliminating the obvious drawbacks related to lifetime and maintenance issues. Supercapacitors are deployed in order to provide a proper startup of the PEMFC and to improve its dynamic response as well. Both, the front-end stage and the output inverter stage, are fully controlled using a single Digital Signal Processor (DSP). The control strategy is based on the average current control method for sinusoidal input current imposition and the standard phase-shift open loop control for the output inverter. During fault conditions or even in conditions of severe voltage sags in the ac network, the PEMFC is activated assuring the continuous energy supply to the output inverter connected to the DC-link and to the AC load as well. In this paper the authors present some theoretical concerns and the main simulation and experimental results obtained.

New Hybrid High-Power Rectifier With Reduced THDI and Voltage-Sag Ride-Through Capability Using Boost Converter

Temporary voltage sags in the side of network supply voltage are the main cause of untimely stops of automated systems that use adjustable speed drives (ASDs). In this context, this paper presents an analysis of a new hybrid three-phase rectifier which was designed to correct the power factor and to promote voltage-sag ride-through capability to ASDs. In order to prove the effectiveness of the proposed solution, this paper shows experimental results for three case studies, evaluating the performance of the proposed hybrid rectifier under voltage-sag conditions. In all analyzed cases, it was proved that the proposed solution is efficient and can be very attractive for high-power applications.

DSP-Based Implementation of Control Strategy for Sinusoidal Input Line Current Imposition for a Hybrid Three-Phase Rectifier

Due to the considerable increase of electronic power processing devices in various segments of industry, the necessity to control and limit the harmonic content of current injected into the distribution systems through the development of pre-regulator converters, has become ever more apparent. Concomitantly, the development of new microprocessors has provided the possibility for the design of sophisticated control algorithms for power electronics converters. In this context, this paper presents an analysis of a hybrid three-phase rectifier developed for power factor correction to be used as an interface of power electronics converters. The main feature of the proposed structure is the power-sharing technique, which assures robustness, cost reduction, and high power density. In this paper, the authors present a complete discussion concerning the controlled rectifiers power contribution and also a complete analysis concerning the total harmonic distortion of current. Mathematical modeling analysis using state space theory is also presented. Experimental results of a 5-kW laboratory prototype using DSP-based control technique are presented in order to corroborate the theoretical analysis.

Retrofitting technique to improve voltage sags ride-through capability of ASD using SEPIC rectifiers

The main cause of ultimately arrest in automated systems, which use adjustable speed drives (ASDs), are temporary voltage sags. Based in this context, this paper presents an analysis of a hybrid three-phase rectifier developed for power factor correction and to promote voltage sag ride-through capability to ASDs. In order to prove the effectiveness of the proposed solution, this paper also presents results of experimental analysis for several case studies, evaluating the performance of the proposed hybrid rectifier before the voltage sags types A, B, and E. Considering all these cases studied, it was shown that the proposed solution is effective and very attractive for applications under high power. Experimental results under normal power supply for an output power of 5 kW are also included.

Grid connected dc distribution network deploying high power density rectifier for dc voltage stabilization

This paper proposes the use of a high power density ac-dc converter to provide higher efficiency and a tight dc bus for connection of electronic loads as well as renewable energy sources. As a new contribution, the authors present a novel hybrid rectifier structure with a series dc-link voltage compensation technique. The proposed hybrid solution is characterized by the fact that a three-phase Boost Converter in parallel input connection and an isolated dc-dc converter in series output connection with an ordinary non-controlled rectifier provides power factor correction and dc bus voltage stabilization. This structure is also capable of imposing line currents with low total harmonic distortion and voltage sag ride-through capability.

DSP-based implementation of input line current imposition strategy for a single-phase hybrid rectifier

Due to the considerable increase of electronic power processing devices in various segments of industry it becomes necessary to control and limit the current harmonic content injected into the distribution systems through the development of pre-regulator converters. In this context, this paper presents the development and experimental analysis of a new structure of single-phase hybrid rectifier with high power factor and low harmonic distortion of current and digital control based on DSP (Digital Signal Processor). In this proposed hybrid rectifier structure the switched converter process reduced portion of active power delivered to the load and therefore the overall efficiency of the structure is increased. The PWM control technique implemented is able to limit the contribution of the switched converter and at the same time impose an input AC current whose harmonic spectrum is in accordance with the limits imposed by the international standard IEC61000-3-2. Mathematical modeling and experimental results are presented corroborating with the theoretical analysis also included.

A bidirectional single-phase hybrid rectifier proposal for sinusoidal input current imposition, DC bus voltage regulation and active power injection onto the AC grid

This paper presents the design and simulation of a Bidirectional Single-Phase Hybrid Rectifier with high a power factor and low harmonic distortion of the current (THD) in accordance with the international standards IEC 61000-3-2 and IEC 61000-3-4. When operating as a power inverter, the imposition of current onto the grid is performed in accordance with IEEE 1547. Therefore, besides power factor correction, the proposed converter provides DC bus voltage regulation, which allows the DC grid to operate with a restricted DC bus voltage even under AC voltage dip conditions or due to a severe reduction of the power provided by renewable energy sources such photovoltaic and wind.