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This study introduces a new modified high-gain interleaved boost–flyback converter with pulse frequency modulation. In the proposed converter, a four-winding coupled inductor and a switching cell are utilized to achieve high voltage gain without requiring a large turn ratio. It presents soft commutation for a wide frequency range, the shared ground connection between source and load, continuous input current with low ripple, and low current oscillation even for cases with low-frequency output voltage ripple. These features make the proposed converter suitable for low-input voltage applications that require a high step-up gain, such as renewable energy systems. The proposed converter is analyzed in steady-state to provide the detailed principle of operation and characteristics, a static gain comparison, a design guide, and losses and efficiency analysis for all the components. Finally, experimental results were obtained from a 450-W prototype with an input voltage of 60/65 V, generating an output voltage of 480 V. The efficiency at peak power is 95.7%.

This article presents a design methodology to improve the power density of integrated converters operating at universal input voltage fulfilling the standards of connection to the grid and load. The proposed integrated two-stage converter is composed of the power factor correction (PFC) stage behaving as a current source to the bus, and the power control (PC) stage which provides continuous energy to the LED load. Traditionally, the low-frequency ripple (LFR) filtering process is performed by the bus capacitor placed in the output of the PFC stage, while the PC stage output capacitor works only as a high-frequency (HF) filter. The idea is to explore the lower and fixed operating voltage characteristics of the PC stage to share the LFR filtering with the PFC stage. Thus, a mathematical analysis is carried out, considering the influence of the LED characteristics, bus voltage, and capacitances to predict the LFR in the LED current. A case study, composed of an integrated buck and buck-boost converter to supply a 75 W LED load, is presented. For the traditional design method, the LED driver needs an 820 uF/160 V PFC bus capacitor and a 10 uF/80 V output capacitor to filter the HF components, representing a total capacitors’ volume of 17.9 cm3. With the proposed analysis, the optimized driver circuit requires a 220 uF/160 V PFC bus capacitor and a 470 uF/80 V output capacitor, resulting in a total capacitors’ volume of 9.7 cm3, providing a volume reduction of approximately 45%.

Energy efficiency plays a crucial role in the development of solar-powered standalone lighting systems, as it directly impacts both the system's autonomy and size, ultimately affecting the cost. In scenarios where a single converter simultaneously functions as both battery charger and LED driver, minimizing energy losses becomes challenging due to the different power levels processed in each mode. The use of gallium nitride (GaN) semiconductors in the converter helps achieving this goal as they allow for a wide range of switching frequencies, maintaining high efficiency even in light-load conditions. However, focusing solely on the converter's efficiency in each task may not necessarily minimize energy losses when considering its 24/7 operating characteristic and charger/driver time ratio. This study introduces a methodology tailored to select circuit components and switching frequencies within a GaN-based dual-purpose converter solution. The primary objective is to maximize system autonomy. A comprehensive analytical model of the converter's losses is paired with a search-based algorithm, enabling the evaluation of commercial components. This evaluation pinpoints the combination that minimizes energy consumption, ultimately leading to a more compact design that efficiently harnesses available resources. Experimental results are showcased for a system with a 30 W driver and 150 W charger, affirming the efficacy of the proposed design methodology. By meticulously selecting parameters, a high-efficiency converter can be realized. This achievement extends the system's autonomy by nearly an hour without necessitating changes to the battery pack's dimensions.

Although advantageous in several aspects, the integration of converters leads to a loss of independence between the converter's stages, since both stages are controlled by the same active switch. This condition makes it impractical to adopt control techniques that act on the duty-cycle to mitigate the low-frequency ripple at the output current without distorting the line current. The low-frequency ripple transferred from the bus voltage to the LED current has been studied for integrated converters operated at constant duty-cycle. To comply with IEEE 1789–2015 recommendation, the integrated converters use large capacitors to mitigate the low-frequency ripple. Converters operating in discontinuous conduction mode (DCM) have been widely adopted because they transfer less ripple to the output than converters operating in continuous conduction mode (CCM). A novel circuit arrangement for the buck-boost power control (PC) stage integrated with a buck-boost power factor correction (PFC) stage is explored in this paper as a technique to minimize the low-frequency output ripple for converters operating at constant duty-cycle and CCM. The proposed circuit provides current feedback to the bus capacitor, acting to reduce the output current and bus voltage low-frequency ripple. A dynamic model for the proposed converter in CCM is obtained and used to determine the output current modulation as a function of converter parameters. It is shown that the proposed topology leads to a smaller low-frequency ripple than a conventional counterpart at the same operating point. A 95 W design example and a prototype supplying an LED load of 98.8 V/960 mA for the proposed circuit and the conventional counterpart are presented. The experimental results show that the proposed arrangement can achieve similar results to the conventional circuit in efficiency, THD, or semiconductor stress, while the obtained output current modulation equals to 8.66% is 3.5 times lower than that in the conventional circuit at same operating point and component values.

This article presents a survey of light-emitting diode (LED) drivers for visible light communication by making a systematization of the most relevant published research. The modulator circuits were classified according to four types. To match the solutions with potential applications, power and efficiency ratings of conventional lighting and data rate of typical multimedia streaming are used as reference values. In conclusion, linear mode modulators (LMMs) lead the number of publications and switching mode modulators (SMMs) are a recent trend. SMMs can provide a good efficiency supporting power levels for indoor and outdoor luminaries and data rate for audio streaming. LMMs support video streaming given the higher data rates; however, the power rating corresponds to, at most, indoor illumination with significantly lower efficiency.

This work presents an analysis and a design methodology for a DC–DC LLC resonant converter applied to off-line LED driving. An investigation regarding the main design parameters that influence the LED low-frequency (LF) ripple has been carried out. The study was based on a mathematical analysis of the converter and employs numerical algorithms to solve a set of equations that accurately describe the converter behavior. Based on this analysis, a novel design methodology that allows for LF current ripple prediction has been devised. A numerical model has been developed to determine the LF current ripple transmission in DC–DC LLC resonant converters and provide a methodology for designing the bus capacitance in two-stage off-line LED power supplies. The work shows that the design of the LLC resonant converter for off-line LED driving is a trade-off between the converter efficiency and the LF ripple transmission. Experimental results were taken from two 46-W laboratory prototypes considering two different design goals: one for LF ripple reduction and another aiming at the highest converter efficiency and better power quality. Furthermore, the design of a two-stage LED driver based on an LLC converter taking into account the LF ripple transmission is also presented.