This paper presents a comparative study of modulation strategies for a full-bridge based unidirectional step-down partial power converter (PPC), focusing on a newly proposed Buck Modulation (BM) scheme. Unlike traditional Phase-Shift Modulation (PSM), BM disables transformer utilization by applying identical PWM signals to all switches in the converter’s full-bridge, effectively converting the topology into an equivalent buck converter. Thermal simulations were conducted to evaluate efficiency performance across different transformer turns ratios and load conditions. Results demonstrate that BM achieves superior efficiency at light loads when the transformer ratio is below unity, and consistently outperforms PSM across the entire power range when the ratio exceeds unity. Furthermore, BM offers a wider and more flexible operating voltage range.

This paper proposes a DC-coupled PEM electrolyzer current control scheme combined with an Input Capacitors Voltage Balancing (ICVB) strategy for a three-channel interleaved dual buck converter topology, aimed at low-carbon hydrogen production. Input capacitors voltage imbalance can lead to improper operation of the interleaved dual buck converter topology, potentially damaging the power components. To address this issue, a control scheme featuring differential operation is proposed to regulate the input voltages, alongside the current control of the electrolyzer, directly influencing the amount of hydrogen produced. By controlling 5 out of 6 inductor currents, it is possible to leave one degree of freedom to control the voltage balance of the input capacitors, indirectly controlling the remaining current due to the operating principle of the topology. Simulation results are presented to validate the proposed control scheme for the proposed system with a nominal power of 1MW.

Battery energy storage systems (BESSs) have be-come integral parts in photovoltaic (PV) energy systems due to their fluctuated nature. The most common solutions in the literature for hybrid PV-battery systems are based on two-stage power converter solutions with separate power converters. However, these solutions increase the cost of the system and the number of required devices. Additionally, leakage currents represent critical issue for safe and reliable operation of PV systems. This paper presents a three-port configuration for hybrid PV-battery grid-connected systems. The proposed configuration includes a common ground connection between the PV side and grid side, which results in the elimination of leakage current components. Moreover, a finite control set model predictive control (FCS-MPC) is presented in this paper for controlling the proposed three-port configuration. The proposed controller achieves the control of multiple objectives simultaneously in addition to having fast dynamic response. Simulation results of the proposed configuration and control method are provided in this paper. The results show the effectiveness of the proposed configuration for hybrid PV-battery systems.

This paper presents a new common grounded (CG) multilevel boost inverter (MI) topology for single-phase grid-tied photovoltaic (PV) applications. The proposed topology has the capability to fully eliminate the leakage currents in PV systems due to the using of the CG connection. Additionally, the proposed topology benefits the high boosting factor capability of the low PV voltage. The proposed topology represents a single stage power conversion system with reduced power components compared to the traditional two-stage PV power conversion systems. In addition, model predictive controller (MPC) is proposed in this paper to control the proposed topology. The proposed controller can control multiple objectives simultaneously without using cascaded controllers. The simulation results with the different case studies are provided. The results confirm the superiority of the proposed CG boost MI topology and the proposed MPC method. Furthermore, fast tracking of the grid active and reactive power demands is achieved using the proposed MPC method.

This paper presents a DC-AC multi-level converter topology that is well adapted for high voltage conversion ratio and will be used to transfer power between a 1500V DC source and 400V/480V AC load or grid. This topology is intented for 1500V Applications. The main potential applications are Uninterruptible Power Supply (UPS), Solar Photovoltaic (PV) Systems and Energy Storage Systems (ESS). The proposed converter topology achieves very high efficiency, up to 98,7% in single conversion architecture using only low-cost silicon (Si) devices with a low blocking voltage.

One of the main challenges associated to the More Electric Aircraft is to significantly increase power density of electrical power systems, such as electromechanical chains applied to actuation systems, without compromising on reliability. Nowadays, the best way of considerably increasing power density of power converters is by the use of disruptive technology such as Wide Bandgap (WBG) semiconductors.

In order to increase the conversion efficiency in photovoltaic (PV) systems, different configurations and topologies were developed. Depending on the application, the converters used for grid connection are built using one or two conversion stages. The advantages of the converters with a DC-stage are mainly the distributed maximum power point tracking algorithm per PV string or PV module and, when required for grid connection, the possibility of voltage elevation. However, the conversion efficiency is lower than configurations with a single-stage as the central inverter. Therefore, the proposed work presents a Partial Power DC-DC converter (PPC) which process part of the entire system power, and the remaining power is directly supplied to the output side. A topology is proposed and the details of its operation are explained based on the operating principle. Simulations are performed in order to evaluate the converter performance.

Multilevel converters are an attractive alternative for medium voltage applications. The Stacked Multicell Converter (SMC), in particular, is a multilevel converter that allows to increase the output voltage level compared with the classical Flying Capacitor Converter, while decreasing the stored energy in the converter. This paper presents the application of Finite Control Set Model Predictive Control (FCS-MPC) in a three phase SMC with two cells and two stacks. The strategy controls simultaneously the load currents and capacitor voltages. simulation results show that the FCS-MPC strategy produces an effective control of the load current, while keeping balanced capacitor voltages. In addition, it is demonstrated that FCS-MPC outperforms Phase Shifted Pulse Width Modulation with linear controllers in transient and steady state operation.

The development of different configurations and topologies implemented in photovoltaic (PV) plants have made possible the increase of efficiency of the system. The traditional configurations of grid-connected PV systems, centralized, string, multi-string and ac-module, have been analyzed and actually most of them are controlled using classic PI control. Furthermore, each of them has different efficiency values due to the inherent associated problems. The large-scale PV plants do not work properly when the modules do not work at the same conditions, for example when some atmospheric and environmental problems are involved, it reduces the reliability of the system. The traditional small-scale PV configurations have a low efficiency due to the dc-boosting stage in order to reach the grid levels. This work presents a grid-connected PV configuration, focused in the improve of the efficiency of the traditional ac-module configuration, a flyback topology for the dc-side and a H-bridge topology for the grid connection will be implemented. Moreover, the proposed control scheme is based on FCS-MPC algorithm.

Converter topology, power devices, passives elements and technology are the keys elements to achieve highly efficient and integrated converters. This article discusses each of these items with a point of load converter application in mind. The potential advantages of series connection are discussed: increase of both the specific power and the efficiency, reduction of semiconductors voltage rating and amplitude of the dV/dt, increase of the apparent switching frequency. The aim of this paper is to investigate how the advantages of the versatile Flying Capacitor topology (DC/DC or DC/AC conversion) can be combined with those of gallium nitride (GaN) power transistors. Integrated screen-printed capacitors are also investigated to reduce parasitic elements and allow double side cooling. A 48V to 5V prototype with screen-printed flying capacitors is built to show the feasibility of such a solution.

In modern power electronics, the design of power converters relies on accurate modeling of losses of all components. Losses in the switches are usually the most important point to be considered in a converter design; however, switching losses are not always provided in datasheets. Typical methods for measuring switching losses, such as the double-pulse method, need the insertion of current and voltage probes across the device. These probes add parasitic elements into the power loop, which modifies the switching behavior, especially when modern semiconductor devices, such as Gallium Nitride (GaN) transistors, are considered. Thus, with the purpose of precisely measuring switching losses, an opposition method test bench has been built to characterize, under real working conditions, one GaN power transistor. The measurement method employed can accurately estimate turn-on and turn-off losses, separately. It does not add parasitic elements to the circuit, which ensures operation at the same conditions of the real converter. Results obtained from this method show the switching characteristics of a specific GaN device and measurements include the power dissipation in a reverse conduction mode. These results help to show the best operation points of the device to maximize the efficiency of a given application.

In this paper, the pre-design methodology of a monolithic Inter Cell Transformer (ICT) in parallel multicell converters is presented for normal operation and with a reduced number of phases. The goal is not to saturate the active phases when the number of cells is reduced. An analysis and comparison of monolithic ICT have been conducted in these two configurations. The increased volume and mass of the robust monolithic ICT is very important for low number of cells. Air-gaps have been inserted in order to limit this augmentation. These air-gaps balance and reduce the overload flux density in active cores during the post-failure operation. In order to validate the theoretical results, a ladder structure of a 6-phase monolithic ICT and a reconfigurable converter has been built. The experimental results for the prototype will be presented by the authors in their next paper.

The parallel association of classical commutation cells is a good solution for increasing the output current driven by the converters while the classical semiconductors technology are used. The control strategies used with this type of connection must be able to ensure good distribution of the output current among the different legs. This paper applies two control strategies based on the Model Predictive Control (MPC) in order to handle these type of connections. A comparison between these control strategies is also carried out by experiments.

This paper presents a new small-scale single-phase photovoltaic (PV) energy conversion system. The topology is based on the series connection of two three-level T-type converters, which form a 5-level converter with two independent maximum power point tracking (MPPT) string connections. The topology merges benefits of string and multi-string PV configurations. The operating principle, the switching states, modulation scheme and control method are addressed in the paper. Simulation results are presented under dynamic conditions and different operating points for the two PV strings, to provide a preliminary validation of the topology and its performance.

In a world of growing need for efficient energy conversion and distributed generation, Dual Active Bridge (DAB) converters represent a prominent converter topology given its soft switching properties and the low number of components, which allow the converter to be highly compact. Depending on the operating voltages and the transferred power, large circulating currents may occur. Parallel connection of converters is a good option in high current applications in order to adapt the converters to the use of standard semiconductors. Interleaving techniques provide, to both sides of the DAB converter, the reduction of the current ripple and the increase of its frequency. As a consequence the filters associated to the converter may be reduced. This paper introduces a new topology of DAB (named DABD3) which has a double three-phase connection in the low voltage (LV) high current side of the converter. This topology allows Zero Current Switching (ZCS) in the high voltage (HV) side switches. It has the same number of switches with the same blocking voltage of a parallel association of three single phase DAB converters. However, it presents lower ripple in the DC bus current and lower switched current in the LV side, which reduces the losses of the whole system.