Nowadays, point-of-load (POL) converters' investments are counted as a main part in power management markets; especially the synchronous buck converters. Today's products forces designers to highly integrate POL converters by increasing the switching frequency; so the latest technology has used megahertz range to obtain this target. On the other hand, increasing switching frequency means increasing the switching losses. Therefore, it is very important to optimize the operating switching frequency tradeoff, which requires an accurate model taking in consideration the converter operating conditions. This paper presents an accurate mathematical loss model taking in consideration the physical behavior of the MOSFET switch in addition to the converter operating conditions. This model introduces accurate equations for every switching intervals and so accurate loss calculations. An integrated POL synchronous buck converter of 5 MHz, 5-1.8 V/3 A prototype is fabricated. The results of the proposed model are compared with simulation and experimental results under variable operating conditions. Good matching between the mathematical, experimental, and simulation results are obtained.

Energy transition from traditional generation sources into new renewable energy generation has become essential for facing climate changes. However, increased penetration levels of renewable energy sources (RESs) make power systems subjected to low inertia problems. Moreover, the continuously growing numbers of electric vehicles (EVs) have made the substantial need for their contribution in power systems. Therefore, this paper proposes a combined fractional-order controller using the parallel combination of tilt-integral-derivative with filter (TIDF) and hybrid fractional-order (HybFO) controllers for robust frequency regulation in interconnected power systems. The proposed controller is advantageous in combining the merits of two fractional-order controllers that result in more robust and effective load frequency control (LFC) at wide range and different types of disturbances. Furthermore, a new application of marine predator optimization algorithm (MPA) is proposed for simultaneously determining the optimum controller parameters in the different power system areas. The existing EVs contribute in performing additional functionality in power systems. EVs help in damping out the frequency and tie-line power oscillations in the proposed work. The two-area interconnected power system is selected as a case study with the installed photovoltaic (PV), and wind generations in addition to distributed EVs among areas. The obtained results show the superiority and suitability of the proposed controller over the traditional controllers in the literature. Additionally, the effectiveness of the MPA is validated and compared with recent meta-heuristic optimization algorithms.

The simple circuit based on DC-DC converters is the main attractive feature of the differential inverter topologies. It has a single-stage and provides modularity and scalability. However, the Negative Sequence Harmonic Component (NSHC) generated at the output terminal may hinder its practical applications. This paper presents a single-stage three-phase isolated differential inverter based on three High-Frequency Link (HFL) transformer-based DC-DC SEPIC converters. The utilized SEPIC converters perform voltage step-up/ down capability with galvanic isolation, which is essential for Renewable Energy Sources (RES). It mitigates the Common-Mode Voltage (CMV) and Electro-Magnetic Interference (EMI). Moreover, this paper proposes a two-loop based d-q synchronous frame grid-current control to mitigate its NSHC. A Type-II compensator and simple NSHC detection circuit are proposed to enhance the inverter's stability and compensate phase-delay of the utilized SEPIC converters. NSHC detection is developed using three cascaded Low Path Filters (LPFs). A 1.6kW inverter prototype was set to validate the performance of the proposed inverter and its control. The control is implemented by the MWPE3 C6713A Expert III DSP board. The proposed topology has a maximum efficiency of 89.744 at 700W output power and 86.4% at full power. The proposed control decreases the NSHC from 40.6 % to 1.614%, which shows its accuracy and precision. Furthermore, THD is reduced from 35.61% to 4.087% and satisfy the recent grid codes (<5%). The simulation results using PSIM software, power loss distribution, and a comparison study of the proposed inverter with similar topologies are also presented.

Microinverters are an essential part of the photovoltaic (PV) industry with significant exponential prevalence in new PV module architectures. However, electrolyte capacitors used to decouple double line frequency make the single-phase microinverters topologies the slightest unit in this promising industry. Three-phase microinverter topologies are the new trend in this industry because they do not have double-line frequency problems and they do not need the use of electrolyte capacitors. Moreover, these topologies can provide additional features such as four-wire operation. This paper presents a detailed discussion of the strong points of three-phase microinverters compared to single-phase counterparts. The developed topologies of three-phase microinverters are presented and evaluated based on a new classification based on the simplest topologies among dozens of existing inverters. Moreover, the paper considers the required standardized features of PV, grid, and the microinverter topology. These features have been classified as mandatory and essential. Examples of the considered features for classifications are Distributed Maximum Power Point Tracking (DMPPT), voltage boosting gain, and four-wire operation. The developed classification is used to identify the merits and demerits of the classified inverter topologies. Finally, a recommendation is given based on the classified features, chosen inverter topologies, and associated features.