This article proposes a new configuration of a modular multilevel converter (MMC) and a Marx generator to generate fast-rising impulse waveforms. This new configuration improves the capabilities of the MMC-based high voltage arbitrary wave shape generator to generate fast-rising impulse since the MMC topology faces many inherent limitations. Similar to the conventional superimposed circuit of the ac transformer or dc rectifier circuit with the Marx generator, three hybrid circuits of MMC and the Marx generator are introduced, where the most optimal choice is made considering the practical aspects of testing, such as the size, cost, and preparation time. Then, a detailed analytical study is performed on the Marx generator circuit and the MMC circuit, and both circuits are coupled together to deliver a complete guideline on choosing various system parameters when the impulse wave shape and the load capacitor are given. The concept of this new hybrid configuration is demonstrated with a scaled-down prototype where the impulse with a rise time of 1 μs is superimposed on different arbitrary wave shapes. Similarly, the MATLAB-Simulink simulation model validates the proposed configuration for a 200, k V dc link voltage and 67 submodules with the desired impulse performance.

Power electronics converters are essential for power generation, transmission, and distribution. The modular multilevel converter (MMC) is highly valued for its versatility, high efficiency, and robust control capabilities. Since MMC is composed of many components, its reliability is crucial for maintaining the availability of electrical power systems. The reliability of the MMC can be evaluated using different methods, such as the military handbook (MIL) and the Mission Profile (MP) methods. By comparing the reliability estimation of the MMC using the MIL and MP methods, this study offers insights into the effectiveness of these approaches. Also, it shows the significant difference in final results between the two applied methods. These findings contribute to the understanding and improvement of the reliability assessment of power electronics converters. Also, the impact of redundancy is scrutinized to make the comparison more thorough.

The development of lithium-ion batteries has experienced massive progress in recent years. Battery aging models are employed in advanced battery management systems to optimize the use of the battery and prolong its lifetime. However, Li-ion battery cells often experience fluctuations in battery capacity and performance during cycling, which makes capacity prediction more difficult. Moreover, the reason for the capacity regeneration phenomenon occurring after resting periods is not clear yet, as well as the influence of cycling conditions on capacity regeneration. A relationship between this phenomenon to cycling state of charge (SoC) ranges and current rates was investigated in this paper on a battery cell with Lithium Nickel Manganese Cobalt Oxide positive electrode. Experimental results show that the capacity increase is a consequence of decreased internal impedance after the resting period. The experiments also showed that a significant power drop and subsequent power regeneration after a resting period occurs only for specific SoC ranges, and applying a resting period after battery cycling can mitigate this power fading process. The semi-empirical model of battery degradation including capacity regeneration is proposed in this paper based on physical processes inside of the cell retaining low computational requirements. The acquired results can be utilized in battery management systems for more accurate state of health estimation and to prolong battery lifetime.

Electric aircraft technology has gained considerable attention and is rapidly developing to mitigate the environmental impact of air transportation and move toward more sustainable modes. Nevertheless, the unique characteristics of electric aircraft pose significant challenges for the charging infrastructure, which must be effectively addressed to facilitate the growth of electric aircraft. This article provides a comprehensive review of the latest developments and future trends in electric aviation, which covers electric aircraft, battery technology, and electric aircraft charging systems. This article also surveys the possible charging system architectures that can be employed for electric aircraft charging. Various power electronic converter topologies that are suitable for future electric aircraft dc fast chargers are presented. This article concludes by identifying future challenges in the path toward charging electric aircraft and discusses potential solutions to these challenges.

This article provides the design procedure of a ±350 V series resonant balancing converter for bipolar DC grids. The process creates a η-ρ Pareto front to design a 3 kW converter with natural convection cooling.

Balancing converters play a pivotal role in bipolar dc grids, and while numerous topologies have been explored, many suffer from drawbacks, such as reliance on bulky passive components, limited soft-switching capabilities, or complex control mechanisms. This article introduces an LC series-resonant balancing converter topology that addresses these issues, featuring smaller passive components, the ability to achieve soft switching across its entire operational range, and simplified control with proper design. By operating in the capacitive region, the converter ensures soft switching for the complete load range, enabling all switches to achieve zero voltage switching (ZVS) turn on. The study reveals that the converter's power flow depends on both the switching frequency (fsw) and the phase shift angle (φ), but notably, when the resonant inductor value is kept sufficiently low, fsw and φ become decoupled, simplifying power flow control. In addition, this article provides detailed design guidelines for the converter's resonant tank and validates the operation and control of the converter through an experimental setup.

This article presents an analysis, multiobjective design, and benchmark of three modified 3 phase shift full-bridge (PSFB) converters that are well-suited for electric vehicle (EV) battery charging applications, covering both typical battery voltage classes (400 and 800 V). These three modified PSFB converters, denoted as the t-PSFB, r-PSFB, and i-PSFB converters, have the ability to reconfigure and provide better efficiency performance in the wide voltage range necessary for public EV battery charging applications. In this article, the characteristics and design considerations of these reconfigurable PSFB converters are discussed in detail. A multiobjective converter design process is proposed to optimize the average efficiency, normalized cost, and power density of the magnetic components and heat sinks. This design process employs the correlations between the cost and performance indexes of the key components derived based on open and accessible components' data to estimate the design objectives. In this way, the design process is not constrained by certain component choices, making it easier to identify the most advantageous design. A benchmark study is conducted among the reconfigurable PSFB topologies and the conventional PSFB circuit using the proposed multiobjective design process. To validate the analysis, a close-to-Pareto-front 11-kW, 45-kHz r-PSFB converter prototype with 640-840-V input voltage and 250-1000-V output voltage ranges is developed and tested.

The urge to reduce the dependence on natural gas for heating at the residential level has led to the deployment of different fossil fuel-free alternatives. In the Netherlands, two technologies are leading the transition: heat pumps, due to their high COP, and photovoltaic–thermal systems, due to their dual electric-thermal output. However, both represent a challenge for users and grid operators, aside from their stochastic behavior. Heat pumps alone can surpass a typical Dutch house's total energy and power consumption. Photovoltaic–thermal systems, as their only electric homologs, usually have a mismatch between generation and demand, causing energy injections to the grid. From the electric perspective, storage systems are a proven solution to reduce the energy exchange with the distribution network. This paper proposes four multi-carrier energy system configurations for a Dutch household, comprising different combinations of a photovoltaic–thermal system, a battery energy storage, a heat pump, and an underground water tank thermal energy system, providing analytical models for every component (including the thermal losses from the thermal storage to the ground), and the space heating and electrical demands. We determined the components’ compatibility and evaluated the combinations considering their thermal performance, electrical performance, and equivalent CO₂ emissions. The results suggest that using a heat pump combined with a photovoltaic system and a battery provides the best trade-off. The photovoltaic–thermal system alone could not supply the thermal demand required for comfortable space heating nor reach temperatures high enough to charge the thermal storage. Combining the thermal storage with the heat pump allows a certain degree of flexibility for the heat pump activation at the cost of COPs between 0.8 and 1.38 when used to charge the thermal storage, thus increasing energy consumption and equivalent emissions considerably.

Power control of flexible loads will play a significant role in energy transition. This work has developed a mixed-integer linear power control (MILP) model that manages electric vehicle (EV) chargers, heat pumps (HPs), and PV rooftops. The power control was tested with and without vehicle-to-grid (V2G) capabilities in different grid types, namely residential, commercial, and mixed grids. Moreover, the effect of different seasons and charger efficiencies was investigated. It was shown that grid characteristics such as EV parking times and building occupations can affect significantly the power control, e.g. the amount of imported and V2G power. Moreover, while V2G power is rarely used due to current V2G round-trip efficiency, future efficiency improvement can lead to a significant increase in V2G use. Finally, the seasonal effect had also a significant impact with Summer being characterized by higher exported and lower imported energy due to the high and prolonged PV power availability.

Modular multilevel converters are favorable for efficiently operating high-power usages. The required number of components significantly increases when higher modularity is introduced for the given voltage level, thus reducing the system's reliability. This article suggests a mixed redundancy strategy (MRS) that combines the operational concepts using active and spare redundant submodules. It is shown that more than 50% higher B10 lifetime (the point in time when the system has a 90% probability of survival) is achievable as compared to reliability improvement using fixed-level active redundancy strategy, load-sharing active redundancy strategy, and standby redundancy strategy with the same number of redundant submodules. The tradeoff between operational efficiency and investment cost is explored to define the boundary for selecting the MRS over other redundancy strategies with varying dc-link voltages and average converter loading, considering a ten-year payback period and equivalent B10 lifetime. The change in viability boundary for the MRS is established with increasing B10 lifetime and its sensitivity to power electronic component costs and assumed failure rate. The effect of power capacity with a higher switch current rating is evaluated. Also, the Monte Carlo simulation methodology is proposed to evaluate the practicality and effectiveness of the proposed MRS scheme. Finally, the insights of this study are applied to existing literature.

This paper proposes a shared multi-stakeholder PV system for traction substations and nearby residential loads to reduce the need for storage, AC grid exchange, and curtailment. The residential stakeholders offer both the base electrical load and the solar panels installation space needed by the traction stakeholder, who brings the peak load and investments to the former. Two case studies were conducted for one year in the city of Arnhem, The cy=Netherlands, using comprehensive and verified simulation models: A high-traffic and a low-traffic substation. The results showed a positive, synergetic benefit in reducing the PV system's excess energy and size requirement for any type of traction substations connected to any number of households. In one detailed example, the multi-stakeholder system suggested in this paper is shown to reduce curtailment by up to 80% in moments of zero-traction load. Generally, the direct load coverage of a PV system is increased by as much as 7 absolute percentage points to the single-stakeholder system when looking at energy-neutral system sizes. This multi-stakeholders system offers then an increase in the techno-economic feasibility of PV system integration in urban loads.

DC energy hubs have emerged as suitable candidates to enhance the electrical infrastructure in a localized approach, allowing future expansion in the transportation sector despite the electricity grid congestion. However, a risk in designing such a hub is that the outcome of the optimization can be a mere consequence of the (lack of) sophistication of its generation and load models. In that aim, this paper presents a sensitivity analysis for a power demand profile for a DC railway traction power substation, taking into account traction power parameters and the heating, ventilation, and air conditioning (HVAC) modeling approaches. It is found that the traction parameters such as total mass can be confidently considered using an averaged value. On the other hand, modeling the HVAC system using an averaged power demand can lead to errors over 6%, especially in the recovered braking energy calculations.

Communication-based distributed secondary control is deemed necessary to restore the state of islanding AC microgrids to set points. As its limited global information, the microgrids become vulnerable to cyber-attacks, which by falsifying the communicating singles, like the angular frequency, can disturb the power dispatch in the microgrids or even induce blackout by pushing the microgrids beyond the safe operation area and triggering the protection. To make the microgrids more cyber secure, adaptive resilient control for the secondary frequency regulation is proposed. It assumes that each converter is communicating with its adjacent converters. With the proposed control, the weight of the communication channel being attacked is automatically reduced, and the more the communicating signals are falsified, the further the weight of that communication channel is weakened. The proposed approach does not rely on attack detection and thereby is easy to implement; Besides, it still works when challenged by a combination of multi-attack signals; Moreover, it applies to multiple communication lines getting attacked cases. Finally, the effectiveness and feasibility of the proposed resilient control scheme are validated by both simulations and experimental results.

This paper presents a control strategy for active power decoupling in a Solid State Transformer (SST) using a cascaded H-bridge (CHB) converter, dual active bridge (DAB) converters, and a high-frequency link (HFL). The strategy balances capacitor voltage and decouples power flow, significantly reducing second harmonic voltage ripple in DC link capacitors and potentially reducing their size.

In the production of green hydrogen, electrolyzers draw power from renewable energy sources. In this paper, the design of Solid State Transformer (SST) for large-scale H ₂ electrolyzers is benchmarked. The three most promising topologies are chosen for design and comparison, including Modular Multi-level Converter (MMC) based SST, Modular Multi-level Resonant (MMR) based SST, and Input-Series-Output-Parallel (ISOP) based SST. The distance between converter towers for insulation and maintenance, the insulation system of the transformer, and the cooling system are designed with practical considerations in order to have an accurate estimation of the volume and weight of the SST. Losses in the switches are calculated based on equations, and losses in passive components are calculated based on FEM simulation. The operating frequency for each topology is optimized to minimize loss, weight, and volume. The best of each topology is then compared with each other to identify the most suitable one for large-scale H ₂ electrolyzers.

Converters that produce an isolated dc output from a three-phase mains supply are often required. Moreover, input power factor correction (PFC) functionality is essential. A standard two-stage conception with ac/dc and dc/dc converters may be used. However, a single-stage or quasi-single-stage solution can simplify the circuitry and increase efficiency; therefore, many variants of single-stage converters have been researched and published. This paper introduces a novel quasi-single-stage resonant topology with an integrated transformer. Additionally, an original control structure is proposed. This converter enables full control over the output dc voltage and current. Another benefit of the proposed converter is a relatively low complexity of its power circuit and control compared to other single-stage converters. The operation principle of the power circuit is explained and the control strategy is also analyzed in detail. A description of the integrated transformer together with aspects of the resonant circuit design are presented. A simulation of the entire converter was performed and evaluated. Furthermore, a test-bench prototype was designed and constructed and is outlined in this paper. The test-bench measurement results are provided and compared to the simulation results. Power factor and efficiency measurements in terms of their dependence on the output voltage and current are included.

Multiport dc-dc converters have been intensively concerned and studied in power electronics-based systems. However, the instability issue and its suppression method are rarely discussed. This article investigates the stability of the triple active bridge (TAB) converter with two constant power loads by impedance-based method, where the output impedance of the TAB converter is derived by the extra element theorem. Then, a virtual impedance-based active damping (AD) control is proposed, where the virtual impedance has four different positions at the output capacitor of the dc port. The effect of the proposed AD control on output impedance and system dynamic response is analyzed. Meanwhile, the range of the virtual impedance is specified. Simulation is performed in PLECS and experimental tests are conducted on a scale-down TAB prototype to verify the effectiveness of the proposed AD control.

The aviation industry, responsible for over 2% of energy-related CO₂ emissions in 2022, aims for Net Zero Emissions by 2050. Despite electric aircraft's environmental benefits and improved operational efficiency, the current battery technology limits their range and size. Based on the optimal system voltage and power profile of the reference all-electric aircraft, this paper presents the design of a hybrid reconfigurable battery pack. The design incorporates a combination of high-specific-energy (263 W h kg^-1 at cell level) and high-specific-power (1800 W kg^-1 at cell level) battery types and its performance is compared with that of a fixed configuration battery pack comprising a single battery type. Simulation results suggest a potential 900 kg (18% lighter than fixed configuration) weight savings with reconfigurable pack, translating into enhanced payload, energy savings, or range extension for 9 PAX Eviation Alice electric aircraft at just 0.4% more energy capacity loss in 500 cycles.