Improved noise immunity for two-sample PLL applicable to single-phase PFCs

Synchronization in a single-phase Power Factor Correction (PFC) is deteriorated, among others, by the combination of the noise introduced by the grid voltage sensing, conducted EMI, the ADC resolution and the sampling frequency used. Low signal-to-noise ratios (SNR) reduce the performance of the Two-Sample (2S) Phase Locked Loop (PLL). This effect can be compensated by including a smoothing filter action without increasing the overall complexity significantly. The resulting 2S with smoothing (2SS) is evaluated and validated by simulation and experimentally over a Totem Pole PFC.This work has been supported by the Spanish Ministry of Science and Innovation under Project RTI2018-095138-BC31 PEGIA - Power Electronics for the Grid and Industry Applications

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

Evaluation of quadrature signal generation methods with reduced computational resources for grid synchronization of single-phase power converters through phase-locked loops

Low-cost single-phase grid connected converters require synchronization with the grid voltage to obtain a better response and protection under diverse conditions, such as frequency perturbations and distortion. Phase-locked loops (PLLs) have been used in this scenario. This paper describes a set of quadrature signal generators for single-phase PLLs; compares the performances by means of simulation tests considering diverse operation conditions of the electrical grid; proposes strategies to reduce the computational burden, considering fixed-point digital implementations; and provides both descriptive and quantitative comparisons of the required mathematical operations and memory units for implementation of the analyzed single-phase PLLs.This work has been supported by the Spanish Ministry of Science and Innovation under Project RTI2018-095138-B-C31 PEGIA—Power Electronics for the Grid and Industry Applications

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”

Two-sample PLL with harmonic filtering capability applicable to single-phase grid-connected converters

The two-sample phase locked loop (2S PLL) in single-phase digitally controlled grid-connected power converters provide synchronization with a minimal computational burden. However, the distortion of the grid voltage deteriorates the performance of the 2S quadrature signal generator. To solve this issue, this article introduces a harmonic filtering (HF) structure based on observers of the input voltage for the fundamental and selected harmonics. The stability and sensitivity of the 2S PLL with HF is analyzed. In comparison with second-order generalized integrator (SOGI)-based HF, the observers provide a narrower bandpass, and the subsequent deterioration of the response time is compensated by adapting the filter gains dynamically. The results obtained, both in simulation and experimentally, validate the proposal and compare its performance with other widely adopted PLLs providing harmonic rejection capability. The computational burden is analyzed and in the case of the proposals depends on the number of observers and the use or not of the adaptive strategy based on steepest descent.This work has been supported by the Spanish Ministry of Science and Innovation under Project RTI2018-095138-B-C31 PEGIA Power Electronics for the Grid and Industry Applications

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”

Rectificador de línea con dispositivos de potencia activos Si MOSFETs.

Este Trabajo de Fin de Grado se ha realizado en su mayoría en el laboratorio de electrónica de potencia de la Universidad de Cantabria. Cuyo fin ha sido el diseño y fabricación de un convertidor rectificador monofásico de potencia de 230 V y 50 Hz con dispositivos MOSFET. Su realización implica la realización de diseños y construcción en los diferentes ámbitos de la electrónica: 1) Instrumentación, 2) amplificación y adaptación de la señal, 3) conversión analógico digital, 4) tratamiento digital de la información con un microprocesador y 5) conversión electrónica de potencia. La etapa de cálculos se ha apoyado con el manejo de herramientas de simulación matemático (Matlab / Simulink) como electrónico (PLECS) y la verificación mediante la obtención de resultados experimentales con instrumentación de precisión. El resultado es la consecución de una plataforma de ensayo de dispositivos de potencia en etapas rectificadores de red monofásica, previa a PFCs activos, abierta a incluir algoritmos de sincronización con la propia red. Se lleva a cabo un extenso estudio de las prestaciones requeridas y de los dispositivos empleados durante el proceso. Utilizando diferentes entornos de simulación y programación que por último han permitido la ejecución del proyecto comprobando su funcionabilidad.<br /

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

Single ADC Digital PFC Controller Using Precalculated Duty Cycles

Traditional digital power factor correction (PFC) uses three sensors to measure the input and output voltages and the input current. Each sensor, especially the input current one, increases the cost of the system and generates power losses in case of resistive sensors. This paper presents a controller for boost PFC converters. It uses precalculated duty cycles generated offline, and applies them to the switch. In order to control the converter with nonnominal conditions, just one analog-to-digital converter (ADC) is used, whichmeasures the output voltage.Measuring the average and the ripple of the output voltage with this ADC, the controller takes compensation action for changes in the input voltage but also in the load of the converter. The average value is used to control the input voltage changes, while the ripple value is used to control load changes. These two loops present low frequency bandwidth, so the ADC and the whole system can be low cost. Finally, a comparator is used to detect the zero-crossing of the input voltage, so the precalculated values are synchronized with the ac mains. In this way, the converter only uses one ADC and one comparator, both with lowbandwidth. Results showthat high power factor and normative compliance are reached, even under nonnominal conditions