Markus Makoschitz

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.

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.

At present, the mobility sector in Europe is in the middle of a transition phase. Combustion engine-based vehicles (CV) are meant to be replaced by electric vehicles of the same type in order to fulfill the zero emissions targets within the next decades. This requires a collaborative approach from the industry, research institutes, and national governments in order to prepare both the necessary vehicle technology and infrastructure accordingly. Even though various attractive charging solutions in the hundreds of kilowatt range already exist commercially, heavy-duty vehicle charging in the multi-megawatt range is still a topic to be investigated in more detail in the scientific community. Therefore, this publication discusses different strategies to enable fast charging in the megawatt range and presents a concept that is directly connected to the medium voltage grid while enabling distributed charging and an optimized carbon footprint due to the adoption of renewable energy systems.

Due to recent advances in the field of wide bandgap semiconductors, medium voltage converters are starting to regain momentum. This is mainly facilitated as SiC MOSFETs with blocking voltages of up to 10 kV and switching frequencies in the 10th of kilohertz range are starting to become commercially available. Therefore, a unidirectional three‐phase medium voltage rectifier based on a diode bridge rectifier and active current injection network is proposed which benefits from a relatively low number of active semiconductor devices compared to already existing medium voltage solutions. Furthermore, sinusoidal mains currents can be achieved due to third harmonic injection techniques.

The European electricity system undergoes significant changes driven by the EU common rules for the internal market for electricity, as well as by the climate action agenda. The future smart electricity system will build upon a combination of a broad range of new and old technologies together working in novel ways. This paper provides an analysis of novel concepts and technologies for building smart energy management applications from the landscape of technologies from two perspectives: Smart Grids and Energy Efficient Building Operation.

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.