This paper presents a comparative study of battery degradation cost models for battery management in residential PV-battery systems under day-ahead optimization. Three models are investigated: a State-of-Health (SoH)-based model, a cyclic (Full Equivalent Cycle, FEC-based) model, and a proposed model that incorporates the interest rate effect on replacement costs. The models are evaluated under two distinct scenarios: winter and summer, providing an estimate of the minimum and maximum battery lifetime. In addition, a linearized model for calendar aging and degradation cost is introduced to reduce computational time. The results show that the SoH-based model exhibits the highest sensitivity to degradation, whereas the proposed model offers a balanced trade-off between cost and lifetime while achieving the lowest computational time.

This paper presents a control strategy for Electric Vehicle (EV) battery charging that combines a soft-switched isolated dc-dc converter with a three-phase unfolding-based Power Factor Correction (PFC) topology and reduced number of inductors. The proposed system introduces a finite cycle-based model predictive control method, which regulates current by optimally allocating discrete switching cycles across multiple energy paths. For instance, operating at a 25 kHz sampling rate with 40 switching cycles per interval (enabling a 1 MHz switching frequency), the controller achieves 2.5% resolution in power delivery while maintaining sinusoidal grid currents and a high power factor. Unlike conventional designs that require three inductors and separate PFC stages, the proposed architecture uses only two inductors and shifts the PFC function to the high-frequency dc-dc stage, significantly enhancing power density and reducing system complexity. A soft-switching modulation strategy ensures that all GaN-based switches operate under zero voltage switching conditions at high switching frequencies (hundreds of kHz to several MHz), effectively minimizing switching losses. Simulation results show a total harmonic distortion below 3% and confirm the proposed system's ability to deliver high efficiency, compact design, and precise regulation across a wide output range making it well-suited for next-generation EV chargers.

The introduction of the three-phase dual-purpose dc-ac/dc power converter (PC), a recent addition to the universal converter family, holds significant promise for improving the reliability and flexibility of modern microgrids (MGs). This paper presents a novel energy management strategy for a flexible hybrid ac/dc MG architecture featuring dual-purpose dc-ac/dc power converters. These converters offer the capability of both dc/ac and dc/dc power conversion, allowing for connection to either the ac bus or the dc bus through simple reconfiguration, thereby providing enhanced modularity and operational adaptability to various MG conditions. Leveraging model-free reinforcement learning (RL) algorithms, the proposed strategy optimizes the operation mode of the dual-purpose converters to minimize the interlinking converter utilization based on historical MG operational data. The feasibility of the proposed MG architecture and the performance of the RL-based energy management strategy are verified by simulation results.

As power systems move towards decentralized models based on renewable energy sources with distributed generation, the role of power inverters in microgrids becomes increasingly important. In this paper, a three-level T-type quasi-impedance source inverter (3L-T-type qZSI) with a grid-forming control structure is studied for the first time in an islanded ac microgrid composed by three prosumers, supplying residential loads. The power sharing among prosumers is achieved through the well-known droop control method with virtual impedance, and proportional-resonant (PR) controller-based voltage and current control loops. A proportional-integral (PI) based control for regulating the dc-link voltage of the T-Type inverter was implemented making use of the boost ability of the qZS network. The proper operation of the microgrid has been tested by simulation with PLECS, demonstrating a robust behavior of the overall system and a good dynamic performance of the proposed control structure for the 3L-T-Type qZSI in different conditions.

A single-phase single-stage flying inductor based buck-boost inverter (S2FIB2I) is presented in this paper. Operation in buck, boost and buck-boost modes gives the proposed topology the ability to inject power into the grid at a wide range of input voltages. In other words, the proposed inverter has a dynamic voltage gain. The direct connection of the negative terminal of the input source with the neutral terminal of the power grid causes that in photovoltaic applications, the problem of injecting even harmonics into the grid is solved and the leakage current is completely eliminated. The absence of electrolytic capacitors in the proposed converter increases the life and reliability of the system. Also, the ability to operate at nonnity power factor allows the proposed inverter to control the reactive power at its output terminals. Theoretical analysis, design of passive elements and 1 kW simulation results are given to prove the accuracy of the proposed inverter performance.

Photovoltaic (PV) string converter for residential dc microgrids is presented. The concept of the converter is based on the interleaved buck-boost dc-dc converter with a wide input voltage range operation capability. The main control unit is a continuous control set model predictive control. The control system uses a simple droop control unit based on a proportional-integral regulator to ensure stability of the grid voltage. An experimental prototype based on a universal solar dc-dc/ac converter with the unfolding circuit was designed, featuring the MPPT voltage window from 150 V to 490 V and the nominal power of 3.6 kW. The efficiency benchmarking of a universal solar dc-dc/ac with connection to the dc microgrid is considered. Three real-world PV string profiles were considered during the experimental verification of the proposed approach. Based on the California Energy Commission (CEC) standard, the efficiency of the approach was well over 97 % in all selected case study scenarios.

In this paper study of the effect of hybrid modulation on inductive-resonant wireless battery charger (in both constant current (CC) and constant voltage (CV) modes) performance characteristics (efficiency, conducted electromagnetic interference levels, etc.) is presented. The study is based on simulation of the wireless charger model in PSIM software. Performances of the wireless battery charger with the hybrid modulation are compared with that of the charger without modulations and with classical periodic switching frequency modulation. Additionally, some recommendations on selection of the hybrid modulation parameters are given. It is shown that the hybrid modulation is effective to improve performances of switching-frequency-modulated wireless battery chargers not only in CC charging mode, but also in CV charging mode.

Estonia is among the countries with the most energy-efficient Near Zero Energy Buildings (NZEBs) in Europe, i.e. their energy consumption is the lowest. From the energy management prospects, on one hand, the rising price of electricity and decreasing the feed-in prices, and on the other hand, the decreasing price of battery energy storage system (BESS) have made the self-consumption of NZEBs profitable. This paper develops a simple tool to study the optimal sizing of BESS and increase the profitability of NZEBs. The BESS sizing is done considering the installed PV capacity in the NZEB, the energy consumption profile, and the local electricity prices. The results of this paper demonstrate to the NZEB owner and planers that in case of self-consumption, investment in PV systems could be more profitable when it is combined with BESS. Simulation results are presented to validate the proposed BESS sizing tool and analyze the sensitivity of results to changes in electricity and battery system price.

In this paper spread spectrum technique based on switching frequency modulation for the first time is applied to closed-loop wireless power transfer (WPT) systems with multi level inverters at the primary side. The effect of switching frequency modulation on the main performance characteristics of WPT system with multi level inverter operating in constant current mode is studied thoroughly. The results show that the spread spectrum technique is useful approach for reduction of conducted electromagnetic emission generated by multilevel-inverter-based WPT system with moderate impact on other important performance characteristics provided that recommendations given are considered.

An indirect model predictive control (iMPC) approach is proposed for regulating a grid current waveform provided by a single-phase inverter connected to a distorted grid. An algorithm implemented in the control system takes into account a significant computational delay. The distorted grid with the 5th harmonic is considered, which imposes additional restrictions on the iMPC and phase-locked loop utilization. Hardware setup involves a three-level neutral point clamped inverter and an inductive output filter. From a finite set of modulation index values, the iMPC current control selects one value for an external fixed switching frequency driver based on the LS-PWM strategy. Relevant cost function composition and modulation index regulation for improvements of transient and steady-state responses are discussed. Simulation and experimental verification is presented.

This paper describes a prototype of a solar inverter based on qZS network that is designed as a competitive solution to the available on the market commercial solutions. Passive and active components selection guidelines are analyzed. It is based on the target efficiency profile and theoretical losses model for active and passive components. Experimental results confirm theoretical predictions. The results and feasibility for commercial application of the proposed solution is discussed.

This paper studies an operation strategy for a single-phase grid-connected 3LT-type qZSI to regulate the active and reactive power flows. This topology is quite promising in photovoltaic system. The different elements are properly calculated, providing simulation results with a good concordance with the theoretical predictions.

In this paper buck-boost inverter based on unfolding circuit is discussed as novel solution for photovoltaic application. Simple control system is proposed and discussed for output voltage control in grid-off mode. Experimental results are presented for wide range of input voltage and power. The main advantage and potential problems are discussed in conclusions.

This study proposes a simple digital control strategy for a single-phase interleaved quasi-z-source inverter (QZSI) with active-power decoupling (APD). Requirements for QZSI and APD passive elements are presented and discussed. The QZSI-APD with the applied control features low input current and power ripples. Firstly, it was achieved by an interleaved approach; as a result, high-frequency ripples are partly compensated. Secondly, APD with a multi-resonant controller allowed a decrease in low-frequency input ripple. Thus, the proposed topology and control reduced the QZSI capacitors significantly. In addition, as compared to a Z-source inverter, QZSI capacitor sizes could be significantly decreased due to lower voltage levels. The study assumed a 2 kW photovoltaic string inverter; our results proved that the interleaved QZSI-APD is a suitable solution for kW-scale photovoltaic systems.

This paper proposes a new modulation technique for an interleaved H-bridge qZS inverter that is intended for the single-phase photovoltaic systems. The potential benefits of this topology are reduced passive components and improved quality of energy generation. The modulation technique developed allows the maximum boost control for a better utilization of the dc-link. It is developed with the required phase-shifted carrier signals and wider shoot-through state generation than in simple boost control approach.

This paper presents the design for the control scheme of a three-level three-phase neutral-point-clamped quasi-Z-Source inverter which employs an LCL filter for the connection to the grid. A state-feedback based control is developed so as to attain a fully decoupled control of the active and reactive power exchanged with the grid. In addition, a PI regulator is tailored in order to control the dc-link voltage of the inverter. The complete control strategy, along with the inherent capabilities of the quasi- Z-Source inverters, signifies that this kind of power converters is suitable for renewable energy source applications.

This paper presents guidelines for component design of the three-level three-phase T-source inverter with continuous input current under maximum boost control proposed recently. Steady state analysis under low-frequency current and voltage ripples in the dc side was made. Component sizes for both with and without low-frequency ripples are estimated and compared. Simulation results have confirmed most of theoretical predictions.

This paper presents an experimental investigation of a single phase three-level neutral-point-clamped quasi-Z-source inverter for photovoltaic application. The prototype and the case study system are described. Experimental results along with theoretical losses analysis are discussed. The implemented maximum power point tracking algorithm was verified in a real photovoltaic system.

This paper describes the operation of a grid-connected PV system based on a single-phase 3L-NPC qZSI using PSCAD as simulation tool for modelling the system: PV array, single-phase 3L-NPC qZSI, filter stage and electrical grid. The control system considers a maximum power point tracking algorithm, a phase loop locked for synchronization with the grid voltage, a control strategy to inject current in phase with the voltage at the point of common coupling and the modulation technique that also take into account shoot-through duty cycle. Simulation results are provided in order to show the viability of using this topology for PV energy systems connected to the electrical grid.

Shoot-through control methods for qZSI-based dc/dc converters are presented and studied. The major goal was to increase efficiency. A new modulation technique, pulse width modulation (PWM) with shifted shoot-through, is compared with the conventional PWM shoot-through control method. The new method reduces switching frequency of bottom side transistors and inherently features partial soft switching. Previous studies have shown that the biggest drawback of PWM control with shoot-through is unequal switching frequencies of transistors. One solution to that problem could be signal swapping that has been proposed by the authors of this paper. All control methods are first simulated and then experimentally verified on a test prototype.

The half-bridge converter with a phase-shifted active rectifier bypasses the traditional hard-switched half-bridge converter with a diode rectifier regarding to high switching losses and parasitic oscillations in the inverter. The presented galvanically isolated step-down DC/DC converter with an improved control algorithm for the full-bridge active rectifier features reduced energy circulation and switching losses. The performance can be improved under wide input voltage and load variations. The advantages of the converter were verified with a 1 kW converter prototype and the test results were in full agreement with the expected waveforms. The presented steady-state operation principle and mathematical analysis of the converter based on the simulation and experimental results can be used as design guidelines for component and parameter estimation in practical applications.

This paper describes a new modulation technique for a single phase three-level neutral-point-clamped qZS inverter. The proposed converter is intended for applications that require input voltage gain and high quality of the output voltage. The simulation and experimental results are presented and discussed.