The integration of multimegawatt fast chargers into local distribution grids is becoming increasingly relevant due to recent initiatives to push for higher charging power, especially for applications like heavy-duty vehicles. However, the high-power capacity of these chargers, especially when multiple units operate simultaneously at specific locations, raises several important considerations for the optimal design and integration of multimegawatt fast chargers. These include, for example, power electronics architectures and dedicated designs, grid stability, and the incorporation of renewable energy systems. Thus, this paper provides a comprehensive analysis of the key factors influencing the optimal integration of these ultra-high-power chargers, looking into impacts on medium-voltage (MV) networks, the design considerations for medium-voltage power electronics in DC chargers, and the potential of renewable energy systems to offset grid demand. Additionally, this paper explores the potential high-level communication requirements necessary for efficient and reliable charger operation, including a proposal for a robust communication interface layer stack. This investigation aims to provide a holistic understanding of the challenges and opportunities associated with integrating multimegawatt fast chargers into existing power systems, offering insights into the enhancement of both performance and sustainability.

A power electronics converter is generally designed for a specific load condition. However, depending on the applications and its mission profiles, the operating load conditions can be distinctly lower than the specified ones (PV cell under shading conditions, etc.). During this light load condition, the efficiency diminishes considerably, especially if Si–IGBT devices are considered within the power circuit. This study explains a light-load circuit extension based on wide-bandgap (WBG, silicon carbide and gallium nitride) material, which can improve the light-load efficiency and transient response of the conventional IGBT-based active rectifiers and inverter. Such an additional circuit extension is, in general, associated with additional cost. Numerous factors, such as the power electronics application itself, mission profiles, converter power rating and sizing of passive components, etc., can shift the break-even point of the upgraded power electronics system in terms of time. Therefore, a profound investigation of the relevant areas of interest is required in advance to ensure the most efficient amortization of the additional incurred costs of the applied circuitry. A 125 kW 3-phase six-switch inverter is discussed to highlight relevant effects in light-load operation that must be considered for final product design.

Wide Bandgap (WBG) devices like SiC-MOSFETs have become quite popular in recent times due to their superior switching characteristics, high current carrying capability and temperature stability. They are being adopted for many different applications and for a wide range of power levels. For the case of PV applications, manufacturers are considering moving to SiC-based topologies due to higher converter efficiencies and improved power density. However, the present industry largely uses hybrid approaches (IGBT + SiC-diode) to optimize system cost. The aim of this paper is to present a fair comparison of an industry-grade hybrid converter with another similar counterpart where only the Si device has been replaced with the SiC device. The effects of such a direct replacement on the efficiency and losses of the converter are studied under various power ratings. Both converters consist of two stages—a boost converter and a three-phase three-level DC to AC converter. Simulation and experimental results comprehensively indicate a higher efficiency (improvements of up to 8 percent points) for the full-SiC converter, and this is more prominent at low input voltages, where the boost converter is active. However, the gains in efficiency are moderate for high input voltages (1 percent point at nominal voltage), where the boost converter is bypassed, and the losses are almost entirely attributed to the inverter. When set in the backdrop of the Austrian inverter market, the use of SiC devices in PV inverters has the potential for an estimated savings of 37.5 GWh/year in terms of loss reduction.