Power flow controllers (PFCs) can give added benefits in meshed High-Voltage Direct Current (HVDC) grids to increase renewables integration. Interline PFCs have been gaining attention for the last decade due to their easy structure and no need for an external power supply. This paper discusses various interline PFC topologies along with their advantages and disadvantages. The existing topologies are compared with respect to several aspects. These aspects include, for instance, modularity, the number of capacitors, the control range of the PFC, the shape of voltage waveforms inserted by the PFC on the lines, number of devices, the directionality of the current, simplicity of the topology, total power semiconductor rating and losses, and protection of the topologies for external faults. It is concluded that the topology of a PFC for a particular application can be chosen depending on the main goal since the topologies come with their advantages and disadvantages when classified based on various aspects.

This paper presents a soft-switched buck converter using Autonomous Gate Drivers (AGDs) for power electronic converters. Operating at a 400 V DC-link, typical of Electric Vehicles (EVs) and industrial systems, the converter achieves Zero Voltage Switching (ZVS) during turn-on and turn-off via AGD circuitry and optimized snubber capacitance. Operating in Triangular Current Mode (TCM), the converter utilizes inductor current ripple to enable ZVS. Experimental results confirm reliable soft-switching and suppression of voltage overshoot under realistic conditions. While the validation uses a buck converter, the proposed AGDs are directly applicable to more complex converters, including three-phase inverters with sinusoidal reference currents, relevant to EVs, renewable energy, and industrial drives. This work demonstrates a scalable solution for reducing switching losses and improving efficiency in advanced high-voltage converters.

The electrification of heavy-duty vehicles (HDVs) is essential for achieving zero-emission freight transport. Conventional 400–800 V powertrains face limitations in supporting megawatt-level fast charging and high continuous power due to excessive current, cable losses, and thermal stress. Recent advances in high voltage (i.e., 1.7 kV, 2 kV, 3.3 kV) silicon-carbide (SiC) power modules and charging standards such as the Megawatt Charging System (MCS, up to 1250 V) have enabled a new generation of 1.2 kV dc-link architectures for HDVs. This paper presents a comprehensive system-level evaluation of increasing the dc-link voltage from 800 V to 1.2 kV, covering the battery, inverter, and motor subsystems. The battery/charging and motor-level results are presented as analytical first-order assessments, whereas the inverter-level loss-modelling methodology is experimentally validated on a 250 kW, 1.2 kV dc-link SiC prototype. A virtual-prototyping framework is used to quantify inverter losses, thermal behavior, and volume trade-offs, and the switching frequency is optimized by jointly considering inverter and motor harmonic losses. Experimental results showthat the analytical models predict measured inverter losses within approximately 10% over the tested operating range. Under the representative charging assumptions adopted in this study, 1.2 kV dc-link voltage enables either an∼56% reduction in cable conduction losses or an∼33% reduction in cable mass, while the prototype achieves an efficiency of ∼99.12%, a specific power density of 49.4 kW/L, and a bounding-box-based volumetric power density of 20.83 kW/L. The results provide system-level assessment and experimentally supported inverter-level design guidance for 1.2 kV HDV powertrains.

This article presents a novel bipolar field excitation system for pole-changing electrically excited synchronous machines. Conventional wireless power transfer (WPT)-based systems realize bipolar field current through receiver-side active converters and wireless gate-signal transmission, which increases complexity and reduces reliability. The proposed approach employs a dual-input, dual-output WPT system with anti-parallel outputs and a self-driven MOSFET-diode configuration, enabling bipolar current flow without rotor-side active converters or control signals. This simplifies the system, reduces control complexity, and enhances reliability. A small-scale proof-of-concept prototype has been experimentally validated, demonstrating bipolar current reversal up to 2.88 A (118 W) with a self-driven rectifier efficiency of 99% under an inductive load emulating the field windings.

A power flow controller (PFC) may be needed to control the currents and power transmitted in the transmission lines in a highly meshed HVDC system. The paper presents a new and simple topology for series interline PFC for a simple 3 terminal HVDC system. Interline PFCs do not need an external power supply to change the current distribution in the HVDC system. The performance of the proposed PFC during steady state operation and ground faults is analyzed in detail using PLECS software. A protection circuit and its design aspects are also proposed for ground faults on one of the cables.

Power flow controllers (PFCs) might be needed in highly meshed High-voltage direct current (HVDC) systems to redistribute the current and power in the various cables. This paper introduces two new unidirectional topologies, which are among the most simple PFC topologies. It describes the working principle, electrical characteristics, various fault cases, and the corresponding protection circuits in detail. Experiments have been conducted on a scaled-down prototype to verify the full-scale HVDC system simulations. Discussion and extension of the PFC with more than two transmission lines are provided.

Two-level voltage source inverters (2L-VSIs) are widely used in industrial motor drives due to their simplicity and cost-effectiveness. However, their pulsating output voltages introduce common-mode voltage (CMV) issues, leading to challenges such as electromagnetic interference (EMI), winding insulation stress, and bearing currents. While adopting an advanced topology or employing common-mode filters can mitigate CMV-based problems, these solutions often increase system complexity and cost. Alternatively, modulation-based techniques offer a simpler, hardware-free approach to reduce CMV. This paper proposes a modulation-based technique that introduces an adaptive carrier phase shift for sinusoidal pulse width modulation (SPWM) to address CMV issues in 2L-VSIs. Unlike conventional methods that rely on fixed carrier phase shifts (e.g., interleaved 0°, 120°, and 240°), the proposed approach dynamically adjusts the phase shift within each switching interval to effectively suppress CMV. The proposed technique was validated through both experimental testing and analytical modeling to demonstrate CMV reduction. This approach offers a practical and scalable solution for industrial motor drives, still having the inherent simplicity and cost-effectiveness of two-level VSIs.

As the demand for hydrogen increases, large-scale electrolyzer plants powered by renewable energy sources are gaining attention. High Voltage Direct Current (HVDC) grids can be used to supply these plants, as they are widely employed to transmit large amounts of renewable energy over long distances. In this paper, a low-frequency transformer-based solution for providing the required output voltage for electrolyzers is explored. Specifically, this paper focuses on designing a transformer cascade that enables high-ratio, high-power voltage conversion. The applicability of transformer scaling laws to this scenario is examined and the increase in transformer window size at different voltage ratings is analyzed. A detailed comparison of single-stage and two-stage transformer solutions is performed, considering factors such as material usage, losses, and leakage impedance. The proposed solutions are modeled and simulated using Ansys Maxwell software. The results indicate that the increase in material costs for a two-stage solution is considerably lower than predicted by conventional scaling laws.

The utilization of soft-switching inverters is essential for achieving high efficiency and low electromagnetic interference (EMI) in electric vehicle (EV) drive systems. However, inductor design for such converters presents significant challenges. In triangular current mode (TCM)-based zero voltage switching (ZVS) inverters, inductors experience large current ripple and variable switching frequency, leading to excessive core and winding losses. This paper presents a design methodology for a high-power filter inductor specifically suited for TCM-based ZVS inverters. A ferrite pot core was selected, and three winding techniques—Litz wire, copper foil, and solid copper wire—were evaluated. The inductance of the three inductors was determined both experimentally and via simulation using FEMM and ANSYS, while power losses were estimated using FEM-based simulations in ANSYS. Experimental determination of 3C91 core loss coefficients was also performed. The optimal configuration required two parallel inductors per phase, resulting in a final three-phase inverter design with six inductors, each 57 mm high and 66 mm in diameter. By integrating experimental measurements with simulation-based loss estimation, the proposed approach reduces core and copper losses, improves thermal management, and enhances power density, making it suitable for next-generation EV powertrains and renewable energy conversion systems.