With the appeal of carbon neutrality, the installation of local renewable energy systems has steadily increased over recent years. For better consuming these renewable energies, the dc microgrid is a promising candidate, especially for the newly built residential place. Recently, the dc-dc converters obtain more and more attentions for building the dc networks with easy and flexible power managing ability. To boost the performance of these dc-dc converters, the soft start-up operation, the efficiency optimization, the fast dynamic response, the circuit parameter estimating method and the fault-tolerant control require more sufficient studies. Thus, this Special Sesson aims to collect research achievements within the scope of dc-dc converters and control techniques.

Topics of interest in this Special Issue include, but are not limited to:

1. New dc–dc topologies with high efficiency, high density, high frequency, and low cost;

2. Advanced modulation schemes for dc-dc converters;

3. Advanced dynamic control strategies for dc-dc converters;

4. Fault diagnosis and fault tolerance techniques for dc-dc converters;

5. Circuit-parameter online estimating schemes for dc-dc converters;

5. Soft start-up and hot-swap operations for dc-dc converters;

6. Analysis and design of magnetic devices for dc-dc converters;

7. Modeling and optimization of thermal design for dc-dc converters.

With the rapid development of renewable energy generation and integration, modern power systems are becoming highly nonlinear, low-inertia and uncertain, which are faced with serious challenges on stability and security. As the bridge between renewable energy generators and the power grid, grid-tied power converters plays a significant role to support the safe operation of power grid especially under various grid faults. How to design, modeling and control for such grid-forming converters to describe and improve their fault-tolerant and grid-support capability is urgent to handle.

Without conventional power supply support, renewable energy dominated power systems often require direct current transmission, lacking voltage and frequency support under extremely low short-circuit ratios, resulting in prominent transient stability issues. At present, the goal of grid connection control for renewable energy generation is still to meet the requirements of grid code. Under grid fault disturbances, power converters mainly adopt passive grid following and fault ride-through strategies, and it is difficult to achieve active support and autonomous operation without fundamentally changing the mindset. The traditional synchronization control with phase-locked loop (PLL) has a narrow operating bandwidth and poor stability adaptability. The existing voltage source control is easily switched to current source control mode due to device stress limitations under grid faults, and the switching of control strategies under normal and fault conditions can easily lead to instability issues. There are issues such as inconsistent transient frequency and voltage response time series, as well as interactive coupling among multiple power converters, which seriously restricts the autonomous grid-forming capability of renewable energy generators. Under the disturbances of power grid faults, the overcurrent issue and the limited transient frequency and voltage support ability of power converters, make it difficult for renewable energy generators to safely ride through and operate continuously.

Thus, the aim of the proposed special session is to report the latest research advances in grid-forming converter and its applications.

Topics of interest include, but not limited to:

1. Transient modeling and analysis for grid-forming converters with complicated dynamics;

2. New synchronization methods for grid-forming converters;

3. Transient stability enhancement for grid-forming converters;

4. Fault current limiting methods for grid-forming converters;

5. Coordinated voltage and frequency control for multiple grid-forming converters;

6. Oscillation mechanism and suppression methods for grid-forming converters;

7. Transient support capability evaluation for grid-forming converters;

8. Renewable-energy based applications for grid-forming converters.

Due to modern switching power amplifiers (including audio amplifiers, radio amplifiers, underwater acoustic amplifier, etc.) continuously operating at a very high switching frequency to reduce distortion and enhance the ability of the information communication, soft-switching technology, advanced circuit topology, and control strategy are more and more important to realize high power density, high efficiency, low distortion, fast transient response, etc. Along with the development of wideband gap devices, faster switching transient, low driving loss, zero reverse recovery, etc., can be achieved, which improves the efficiency and distortion characteristics and brings new opportunities and challenges to the power amplifier. The aim of the proposed special session is to report the latest research in advanced circuit topology, control strategy, and wideband-gap devices based power amplifiers.

Power amplifiers are also needed for power hardware in-loop (PHIL) simulation, as well as test equipments. Compared with the radio frequency amplifiers, the power will be much higher, and the bandwidth is much narrower. Nonetheless, the high-power amplifier needs to have a considerably broad bandwidth to mimic the dynamics of the components, e.g. motor drive, grids, batteries, electrolyzers, etc. Multi-level and multi-phase topologies are promising techniques for this kind of high-power amplifiers.

Topics of interest include, but not limited to:

1. Circuit topology innovation of the power amplifier;

2. Soft-switching technology of the switching power amplifier;

3. Modeling and distortion analysis;

4. Optimization design for high efficiency, low distortion, fast transient response, etc;

5. Advanced DC-DC power supply for power amplifier;

6. Advanced control and modulation strategy for wideband or narrowband power amplifier;

7. Wideband-gap-devices-based high-frequency switching power amplifier;

8. Characteristic analysis of wide-band gap devices in switching power amplifier;

9. Advanced manufacturing for power amplifier ICs;

10. Power-amplifier based applications.

11. Multi-level, multi-phase, multi-modular converter topologies

E-mobility is playing an increasingly critical role in the clean energy transition. To replace the still main-stream fossil oil-fuelled fleet with electric vehicles (EVs), the enabling technologies include fast chargers (a charging time of 15 mins will be comparable with that for normal car refueling) and battery systems with high safety and accurate state estimation (SOC, SOH, RUL, etc.) capability. Technological advancements are happening in both EV chargers from power electronics (e.g. to maintain high efficiency in the voltage range of 200 V ~ 1000 V) to smart charging algorithms (e.g. to facilitate Vehicle-to-Grid integration, V2G), and in battery systems from novel battery cell design to AI-empowered battery management systems and energy management systems. Additionally, in high-power charging applications (e.g. heavy-duty truck charging), stationary batteries are used in combination with EV chargers to reduce the needed capacity of the grid connection and thereby the installation cost. The aim of the proposed special session is to report the state-of-the-art EV charging and battery control technologies for enhancing the overall performance of EVs and their integration with grids.

Topics of interest include, but not limited to:

1. Power electronics for EV chargers
2. High-power EV charging in both passenger cars and heavy-duty trucks
3. Charging energy hubs
4. Smart charging
5. Battery modelling and state estimation
6. Battery fault diagnostics and prognostics
7. EV energy management techniques
8. Second-life battery technologies and applications

Compared with Silicon based power semiconductors, WBG power semiconductors, especially SiC MOSFETs and GaN HEMTs devices, have some device performance superiorities, e.g., faster switching speed, higher blocking voltage, higher junction temperature, etc. Therefore, WBG devices are penetrating into various power electronics applications, e.g., automotive, consumer goods, energy storage, etc. However, along with the better performance, the WBG device packaging is also seeing challenges from various aspects, e.g., low inductance packaging design, high temperature packaging material and process, different reliability issues and evaluation methods. To fully utilize the WBG device performance, new packaging technology for WBG devices are required. The aim of the proposed special session is to report the latest research achievements in WBG device packaging and its applications.

Topics of interest include, but not limited to:

1. WBG Device modeling and simulation;

2. WBG Device package design & analysis;

3. WBG Device reliability;

4. Novel packaging structures;

5. Advanced Packaging Materials and Processing;

6. Accurate measurement and characterization;

7. Packaging EMI issues;

8. Advanced thermal management;

9. WBG power ICs;

10. System Integration.

With the proposal of national strategic goals of “dual carbon”, the new-energy electricity has deeply penetrated the automotive and aircraft industries. Where, how to realize power conversion and driving in a high efficiency, high power density and high-reliability way becomes a major challenge.  Fractional calculus has infinite dimensions in nature, and has shown amazing potential in the study of problems such as memory features or intermediate processes, and is known as 21st-century calculus. The materials and devices of real physical systems are not ideal, and their constitutive relations can be described more accurately by fractional calculus. The Special Issue aims to attract original research for novel mechanisms and techniques and open up an avenue for expanding the application of fractional-order and other emerging power electronics in new energy vehicles and aircraft.

Topics of interest include, but not limited to:

1. Topology, control and parameter identification for fractional-order power electronics

2. Fractional-order filter, low-frequency ripple suppression and other applications

3. Artificial intelligence-assisted optimization design for fractional-order power electronics system

4. Modeling and stability analysis for fractional-order power electronics system

5. Advanced predictive control of electrical drives and power electronics

6. Wireless charging technology in new energy vehicles and aircraft

7. Health monitoring and lifetime prediction of power converters 

8. Z-source converter, High-frequency link converter, high-gain converter, switched-capacitor converter, and other emerging converters in new energy vehicles and aircraft

The integration of electric vehicles (EVs) into smart grids, particularly in the context of Vehicle-to-Grid (V2G) systems, poses unique challenges. These challenges include potential grid disturbances, instabilities, and concerns about battery lifetime and performance. With the advancements of smart technologies, promising solutions are emerging that not only optimize battery management, enhance grid stability but also provide advanced monitoring and management, ensuring the efficient operation of V2G systems. This special session aims to bring together researchers, industry experts, and academicians to discuss and showcase the latest advancements in integrating EVs into smart grids, emphasizing the role of smart technologies in ensuring battery health, grid stability, and energy efficiency.

Topics of interest include, but not limited to:

1. Smart technologies for grid integration and energy transfer.

2. Energy management systems (EMS) in V2G.

3. Digital Twins in battery management: real-time monitoring and predictive maintenance.

4. Smart techniques for battery state monitoring, lifetime prediction, and fault diagnosis.

5. Learning strategies and physics-informed methods for enhanced battery management.

6. Cloud-edge cooperated prognosis and health management of EVs and grids.

7. Charging load forecast and optimal scheduling of charge in large-scale EVs.

Hydrogen energy is gaining increasing attention as an efficient and low-carbon energy carrier. Among the various methods of hydrogen production, water electrolysis for hydrogen generation stands out as the most promising green approach, aligning seamlessly with the global trend of low-carbon emissions and energy development. Currently, using renewable electricity for water electrolysis presents the least carbon-intensive method among various approaches to sourcing hydrogen. Nevertheless, hydrogen production systems face challenges such as decreased efficiency due to unstable power supply and accelerated aging of electrolytic cells. Through the exploration of coordinated control among system components, optimization of system capacity, electrolyzer modeling, energy management strategies, advanced control theories, fault detection, as well as the low voltage high current switching converters, it becomes viable to substantially enhance the efficiency and reliability of hydrogen production systems. The aim of the proposed special session is to report the latest research advances in high-efficiency and dependable hydrogen production systems and its applications.

Topics of interest include, but not limited to:

1. Coordinated Control;
2. Capacity Optimization;
3. Electrolyzer Modeling;
4. Energy Management Strategy;
5. Advanced Control Theory;
6. Fault Detection;
7. Low Voltage High Current Switching Converters;
8. On-grid/Off-grid Renewable Power to Hydrogen Production.

Abstract:

Multilevel inverters (MLI) are an arrangement of power semiconductors and capacitors that allow high value and high quality voltages to be achieved. Multilevel inverters have exhibited continuous development in the last two decades. Indeed, initially designed to work at medium voltage and high power, today they operate even in low voltage applications. In recent years, interest in multilevel inverters has increased to achieve more compact designs, with better efficiency and greater reliability. This is how we can see applications in heavy industries, photovoltaic generation and wind generation. The increase in electric cars operation from 400 to 800 V DC voltage has increased interest in the use of multilevel inverters in the main drive and in fast charging stations. The aim of the proposed special session is to report the latest research advances of multilevel converters in power electronics.

Topics of interest include, but not limited to:

1. Advanced modulation and control of multilevel converters
2. Novel multilevel topologies
3. Application of multilevel inverters in drives
4. Wind, photovoltaic and energy storage applications
5. Electromobility applications
6. Power system applications
7. High efficiency high power density multilevel converters
8. Reliability and fault tolerant control of multilevel converters