This paper presents the characterization of a TIG welding process carried out by means of an arc welding power supply able to provide dc or pulsed current. The arc welding power supply is based on resonant power converters and an FPGA-based control circuit. Dc and multiple pulsed operations up to 1 kHz with different pulse widths have been tested. The operation of the proposed welding power supply has been compared to that of a high-quality commercial welding machine. Regarding performance, the investigated electrical parameters are: power factor, power conversion efficiency and the energy consumption of the process. The radiography and mechanical properties of the welds have been examined. The mechanical properties of the welded joints characterized through tensile tests are the yield stress, tensile strength and the strain under maximum stress. In addition, the impact properties of the joints were determined through Charpy tests and the curves relating energy absorbed and temperature were obtained. The results show an improved performance of the proposed arc welding power supply over the commercial counterpart, with higher efficiency and power factor, as well as lower energy consumption. The yield stress and tensile strength results indicate that the welded plates using pulsed modes with the proposed power supply are comparable to the reference weld performed with dc operation using the commercial welder. Remarkably, it was observed that the ductility of the welded plates using pulsed modes with the proposed power supply outperforms those of the reference weld carried out with dc arc using the commercial welder.

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.

In-depth models of single-phase grid-tied power converters facilitate the examination of low-frequency (LF) interactions among loads, distributed energy resources (DERs), and synchronous generators by operators and designers. These interactions are becoming increasingly significant with the growing integration of power electronics into electrical grids. This article extends the envelope modeling (EM) technique to develop LF linear time-invariant (LTI) circuit models for single-phase grid-tied power converters. The models utilize an independent phase signal that aligns with the most appropriate reference frame. This methodology preserves the LF dynamics inherent to the power converter and control system. The practicality of this method is evidenced by constructing a model for a bridgeless totem-pole power factor corrector (PFC), which includes a zero-crossing detector (ZCD) and operates without closed-loop regulation. The outcomes from this model are juxtaposed with those from a switched model and other well-stablished modeling techniques for comparison. Furthermore, a commercially available circuit design featuring current and voltage control loops is simulated, and the results are corroborated with experimental data. These experiments are conducted under disturbances influencing the converter's performance within its linear operational range.

This paper presents the design considerations, control strategy and resulting performance of a two-stage ballast system; power factor correction (PFC) and resonant inverter (RI), for metal halide lamps (MHL). Medium and long term stability, with regard to utility line perturbations and lamp aging, is achieved by the PFC stage controlled in power mode, while the short term stability is assured by the high output impedance of the LCC inverter, operating in open loop at constant switching frequency. Power mode control requires over voltage and short circuit protection. The LCC resonant inverter is designed in such a way that the maximum power supplied to the lamp is inherently limited, provided that the input voltage is also limited. Hence, the protection requirements are reduced to limit only the maximum voltage supplied by the PFC stage to the inverter stage. By boosting the PFC output voltage with respect to the nominal value during the protection mode two benefits are achieved: 1) the ignition performance using the resonance of the LCC circuit is improved, since it is not necessary to reach the highest voltage gain frequency which is more sensitive to frequency or component tolerance. Hot re-ignition performance is also improved since the required voltage gain is also less sensitive to component thermal deviation. 2) The warm-up time is clearly reduced in comparison to electromagnetic ballast or other non-controlled ballast since the RI input voltage increases when the lamp power is below the target value to reach the power level imposed by the reference

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 LC_pC_s 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 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 effect, 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 effect 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.