In this paper, a design method for a photovoltaic system based on a dual active bridge converter and a photovoltaic module is proposed. The method is supported by analytical results and theoretical predictions, which are confirmed with circuital simulations. The analytical development, the theoretical predictions, and the validation through circuital simulations, are the main contributions of the paper. The dual active bridge converter is selected due to its high efficiency, high input and output voltages range, and high voltage-conversion ratio, which enables the interface of low-voltage photovoltaic modules with a high-voltage dc bus, such as the input of a micro-inverter. To propose the design method, the circuital analysis of the dual active bridge converter is performed to describe the general waveforms derived from the circuit behavior. Then, the analysis of the dual active bridge converter, interacting with a photovoltaic module driven by a maximum power point tracking algorithm, is used to establish the mathematical expressions for the leakage inductor current, the photovoltaic current, and the range of operation for the phase shift. The design method also provides analytical equations for both the high-frequency transformer equivalent leakage inductor and the photovoltaic side capacitor. The design method is validated through detailed circuital simulations of the whole photovoltaic system, which confirm that the maximum power of the photovoltaic module can be extracted with a correct design of the dual active bridge converter. Also, the theoretical restrictions of the photovoltaic system, such as the photovoltaic voltage and power ripples, are fulfilled with errors lower than 2% with respect to the circuital simulations. Finally, the simulation results also demonstrate that the maximum power point for different environmental conditions is reached, optimizing the phase shift factor with a maximum power point tracking algorithm.

Summary The dual active bridge (DAB) converter has high efficiency and versatility; hence, such a converter has been used to design photovoltaic (PV) applications with both step‐up and step‐down voltage capabilities. However, PV systems require maximum power point tracking (MPPT) controllers to track the optimal operation conditions; moreover, PV voltage controllers are required to reject load perturbations that reduce the MPPT performance. This paper describes the operation of a DAB converter in PV systems and compares the performance of the DAB converter with a classical boost solution. In addition, this paper also presents a systematic analysis of the control techniques for DAB converters in PV applications, which provides useful information for selecting the most suitable approach for a particular application.

This study proposes a charging/discharging system of energy storage devices (ESDs) to regulate the voltage of a dc bus. The proposed charging/discharging system is formed by a zeta/sepic converter and a sliding mode controller (SMC). The SMC uses a single sliding surface to regulate the dc bus voltage for the three operating modes of the charger/discharger converter (charging, discharging, and stand-by) and for ESD voltages lower, equal, or higher than the dc bus voltage. This study includes the stability analysis of the SMC and a design procedure of the SMC parameters. The charging/discharging system is simulated in PSIM, where the results confirm that the proposed SMC regulates the bus voltage in charging, discharging, and stand-by modes for different operating points of the system. Finally, the proposed charging/discharging system was constructed for demonstrating the feasibility of the solution for real applications. Moreover, the experimental results obtained in such a platform put into evidence the accuracy of the proposed SMC in regulating the bus voltage in all the possible conditions: bus voltage lower, equal or higher than ESD voltage, and during charge, discharge, and stand-by modes of the ESD.

La necesidad de proveer soluciones energéticas sostenibles para las zonas no interconectadas de Colombia, dependiendo de los recursos renovables disponibles en cada zona, supone un desafío respecto al análisis de viabilidad técnico-económica de las alternativas de solución a través de las microrredes. Este documento tiene como objetivo analizar el impacto técnico-económico de introducir celdas de combustible en la reducción de costos a lo largo del tiempo de vida de una microrred para zonas no interconectadas, empleando el software HOMER. Dicho impacto se evalúa tanto en el diseño técnico de la microrred como en el Valor Presente Neto y en el Costo nivelado de Energía ($/kWh). El análisis se realiza a partir de la cuantificación de la demanda de un poblado prototipo, el dimensionamiento y costo de las tecnologías que conforman la microrred para atender la demanda, y la disponibilidad de los recursos renovables solar y eólico de dos zonas localizadas en diferentes latitudes no interconectadas de Colombia. Adicionalmente, se analiza el efecto de introducir las celdas de combustible en el mix energético, resaltando las ventajas obtenidas al comparar cada caso frente a una generación tradicional basada en consumo de Diésel.

Solar energy is a source of sustainable energy and its optimal use depends on the efficiency and reliability of PV systems. Dual active bridge converters are a solution to interface PV modules with the grid or high voltage requirement applications due to the high voltage-conversion-ratio and high efficiency provided by such a converter. The three main contributions of this work are: an extensive mathematical model of a DAB converter connected to a PV module including protection diodes, which is intended to design non-linear controllers, an explicit linearized version of the model, which is oriented to design traditional control systems; and a detailed and replicable application example of the model focused on maximizing the power extraction from a PV system. The modeling approach starts with the differential equations of the PV system; however, only the fundamental and average components of each signal is used to represent it. The control-oriented model is validated using a detailed circuital simulation. First, through the comparison of frequency and time diagrams of the proposed model and a detailed one; and then, through the simulation of the PV system in a realistic application case. PV voltage regulation and maximum power extraction are confirmed in simulation results.

Due to the wide usability of thermoelectric generators (TEG) in the industry and research fields, it is plausible that mismatching conditions are present on the thermal surfaces of a TEG device, which induces negative-performance effects due to uneven surface temperature distributions. For this reason, the objective of this study is to characterize numerically the open-circuit electric output voltage of a TEG device when a mismatching condition is applied to both the cold and hot sides of the selected N and P-type semiconductor material Bi0.4Sb1.6Te3. A validated numerical simulation paired with a parametric study is conducted using the Thermal-Electric module of ANSYS 2020 R1, for which different thermal boundary and mismatching conditions are applied while considering the temperature-dependent thermoelectrical properties of the N and P-type material. The results show an inverse relationship between the open-circuit voltage and the mismatching temperature difference. When a mismatching condition is applied on the hot side of the TEG device, the temperature-dependent electrical resistance has lower values, deriving in higher voltage results (linear tendency) compared to a mismatching condition applied to the cold side (non-linear tendency).

No abstract

No abstract