Unfolded resonant converter with current doubler structure module for welding applications

A new multiphase resonant converter arrangement with series dual phase in the primary side and parallel dual current doubler in the secondary side, operating as a phase shift controlled current source is presented. Sharing the voltage and current stress among the active and passive components with a high DC input voltage and arc current motivates this structure, which also uses WBG devices to increase the efficiency at high switching frequency. The resulting module is intended to operate in continuous and pulsating mode and can be parallelized to extend the output arc current rate.This work was funded by the Spanish Ministry of Science and the EU through the project TEC2014-52316-R: ‘Estimation and Optimal Control for Energy Conversion with Digital Devices’ ECOTRENDD

Alternating current welding using four quadrant switches

Welding metals such as aluminum and magnesium requires AC current. This work proposes a novel control strategy for a high-frequency rectifier built with four quadrant switches (4QSW) to transform high frequency AC current (125 kHz) into the welding arc bipolar current, controlled in amplitude, frequency and even DC offset. The rectifier is connected to the output of a resonant inverter to achieve positive and negative polarity discharges both voltage and current by operating in two quadrants, i.e. positive and negative. As long as the input power to the converter is supplied by a current source, the typical dead-time set to avoid short circuit conditions jeopardize the safe operation of the switches. A field-programmable gate array (FPGA) is selected to implement the digital control due to its high resolution for the purpose to adapt the 4QSW's drive signals without dead-time in the most accurate manner.This work was supported by FEDER and the Spanish Ministry of Science through the project CICYT-FEDER TEC2011-23612: “Power conversion with new digital control techniques and soft-saturation magnetic cores

Analysis of teaching methodologies for electronics in non-specialized engineering studies

Since the academic year 2011-2012, the Electronics courses have started to be taught within the curriculum of the new Degree in Mechanical Engineering and the new Degree in Electrical Engineering, which are part of the undergraduate academic offer of the University of Cantabria (Spain). Both courses follow a common teaching and learning methodology regarding, not only the syllabus contents and organization, but also the assessment of competencies. During four academic years, changes in the course syllabus have been done, as well as different assessment procedures have been developed and analysed. In this way, the teachers of these two courses have been able to evaluate the extent to which students have acquired the expected competencies and also to draw conclusions about the most suited learning methodology to both student profiles, with the specific objective of decreasing the dropout rate

Power source electronic ballast for electrodeless fluorescent lamps

This paper presents the design, control strategy and experimental results of a two-step, power factor correction stage (PFC) and resonant inverter (RI), electronic ballast proposal to supply 150 W electrodeless fluorescent lamps (EFL). The PFC acts as a controlled power source and provides mid and long-term stability to the system, while the stability of the current through the lamp is achieved with the RI. In addition, the power-mode control requires limitation of the output voltage. The dual operation mode of the PFC (voltage source mode and power source mode) enables an e cient soft resonant ignition and the implementation of simple dimming regulation.This work has been supported by the Spanish Ministry of Science and Innovation and the EU through the projects CICYT-FEDER-TEC2014-52316-R: “Estimation and Optimal Control for Energy Conversion with Digital Devices, ECOTRENDD” and RTI2018-095138-B-C31 PEGIA: “Power Electronics for the Grid and Industry Applications”

Pulsed current source with active control of the on-time current for LED lamp driver applications

This paper presents a simplified envelope model to study the dynamics of a phase-controlled resonant converter suitable to drive light emitting diode (LED) lamps. The approximate closed form of the transfer function is obtained from the proposed reduced-order model. The fast dynamics of the resonant converter allows us implementing a pulsed current source with active control of the on-time-current free of instabilities and flicker effect with a type II or integral-single-lead controller. A 120W prototype intended for street lighting applications has been built to validate the study.This work is sponsored by the Spanish Ministry of Science and the EU through the project CICYT-FEDER- TEC2011- 23612: “Power conversion with new digital control techniques and soft-saturation magnetic cores”

Two-phase resonant converter to drive high-power LED lamps

This paper presents the design and modeling of a two-phase resonant converter that drives a LED lamp with a high-frequency pulsed current free of instabilities and flicker efect, fulfilling the recommendations of the IEEE PAR 1789-2015, so that it enables visible light-based communication at a 10 kB/s bit rate. The dynamic study of the converter takes into consideration the efect of the reflected impedance of the output filter on the AC side. In order to evaluate the dynamic response of the converter, a Spice model is defined. A 120 W prototype intended for street lighting applications has been built to validate the analysis and modeling.This work has been sponsored by the Spanish Ministry of Science and Innovation and the EU through the projects CICYT-FEDER-TEC2014-52316-R: “Estimation and Optimal Control for Energy Conversion with Digital Devices, ECOTRENDD” and RTI2018-095138-B-C31: “Power Electronics for the Grid and Industry Applications”

Sistema electrónico de potencia con control digital reconfigurable para máquinas de electroerosión

Sistema electrónico de potencia con control digital reconfigurable para máquinas de electroerosión. Sistema electrónico de potencia con control digital reconfigurable para máquinas de electroerosión, constituido por convertidores de potencia resonantes actuando como fuente de corriente y controlando la calidad de cada impulso. Cuenta con los siguientes elementos: una Red de alimentación, un convertidor electrónico ca/cc, un convertidor electrónico cc/ca de alta frecuencia, un transformador, un rectificador ca/cc de alta velocidad, un sensor y adaptador de señal entre electrodo y pieza, un circuito de control de la fuente de impulsos y del servomecanismo que sitúa el electrodo sobre la pieza. El sistema genera la tensión de ruptura del dieléctrico, el control de la descarga y la protección en cortocircuito. Reconoce formas de onda y se autoajusta para conseguir las máximas descargas efectivas. Tiene como parámetros de control de cada impulso: la distancia entre electrodo y pieza, la frecuencia y el ancho de impulso de mecanizado, y la señal de protección.Solicitud: 200202481 (28.10.2002)Nº Pub. de Solicitud: ES2206058A1 (01.05.2004)Nº de Patente: ES2206058B2 (01.04.2005

Multiphase resonant converter with output current multiplier for battery charger applications

This paper presents the analysis and design of a multiphase resonant converter suitable for high-current low-voltage battery charger applications. In order to reduce the conduction losses, the inverter stage of the converter is obtained from the parallel connection of N class D LCp resonant inverters. In the same way, the output stage is based on a current multiplier, obtained through the parallel connection of two current-doubler rectifiers. The regulation of the charging current is implemented at constant frequency, modifying the phase displacement of the drive signals. The battery charger is designed for a high-performance Absorbent Glass Mat (AGM) battery; at present, widely used in micro-hybrid vehicles.This work was funded by the Spanish Ministry of Economy and Competitiveness, the Principality of Asturias Government and the European Union (ERFD), under Research Grants FC- 15-GRUPTNI4-073 and DPI2013-46541-R and the Spanish Ministry of Science and the EU through the project TEC2014-52316-R: 'Estimation and Optimal Control for Energy Conversion with Digital Devices' ECOTRENDD

Battery charger based on a resonant converter for high-power LiFePO4 batteries

A new battery charger, based on a multiphase resonant converter, for a high-capacity 48 V LiFePO4 lithium-ion battery is presented. LiFePO4 batteries are among the most widely used today and offer high energy efficiency, high safety performance, very good temperature behavior, and a long cycle life. An accurate control of the charging current is necessary to preserve the battery health. The design of the charger is presented in a tight correlation with a battery model based on experimental data obtained at the laboratory. With the aim of reducing conduction losses, the general analysis of the inverter stage obtained from the parallel connection of N class D LCpCs resonant inverters is carried out. The study provides criteria for proper selection of the transistors and diodes as well as the value of the DC-link voltage. The effect of the leakage inductance of the transformer on the resonant circuit is also evaluated, and a design solution to cancel it is proposed. The output stage is based on a multi-winding current-doubler rectifier. The converter is designed to operate in open-loop operation as an input voltage-dependent current source, but in closed-loop operation, it behaves as a voltage source with an inherent maximum output current limitation, which provides high reliability throughout the whole charging process. The curve of efficiency of the proposed charger exhibits a wide flat zone that includes light load conditions.This work was funded by the Spanish Ministry of Science and the EU through the projects RTI2018-095138-B-C31: “Power Electronics for the Grid and Industry Applications”, TEC2016-80700-R (AEI/FEDER/UE), PID2019-110955RB-I00, and by the Principality of Asturias via Project FC-IDI/2018/000226

Converter With Four Quadrant Switches for EDM Applications

This paper presents a high-frequency rectifier stage using four quadrant switches as synchronous rectifiers for an electrical discharge machining (EDM) power supply. The EDM impulse generator is a series–parallel resonant inverter operating in current-mode. The device specifications and drive requirements of the converter are studied with the objective of generating unipolar and bipolar current waveforms suitable for different types of EDM operations