It starts with efficient components, developed efficiently
The efficiency of power converters, particularly in voltage categories to ~10 kV, begins with wide band gap devices, for example, in solid state transformers. But other contributions are made by modular technologies, that can be combined in series or in parallel also to reduce passive components. While parallelization used to rely on simple synchronization, interleaved modulation, apart from significantly reducing the need for inductances can be optimised for other factors, like the component lifetime.
Digital twins and power-hardware-in-the-loop facilitate the synchronised design of hardware and the corresponding control software. They also simplify testing, by supporting virtual environments where the rest of the system can be emulated. This not only takes more testing offline, it also enables the use of artificial intelligence to achieve higher levels of optimisation. This is an approach that the team in Kiel has been using, for example, to demonstrate mult-iport technology topologies for DC-DC converters as well as Modular Multilevel Converters with integrated junction temperature estimation for optimal services to the electric grid.
Supplying the right solution through understanding the demands
While improving converter efficiency is one side of readying the grid for the future, another important aspect is understanding the changing and growing variety of loads. The use of batteries is expanding from cars to also include heavier vehicles, as an alternative not only to fossil fuel, but also to hydrogen.
This means a spectrum of charging speed requirements, which in turn involves different technologies for charging stations. These could range from high-frequency solid-state transformers (reducing the use of metals, as well as size), to reducing the number of iso-lation stages, to increase overall efficiency. There are also new demands on the network, which is likely to shift to more distribution of low and medium voltage DC. This is where multiple active bridge technology, based on the use of multi-winding transformers, as well as Modular Multilevel Converters could be key.
New opportunities through a more holistic perspective
As the charging stations and grid become more sophisticated, they also open the door to the emergence of a widened role for power converters. As a source of information they can interact, in a proactive, grid-forming way, to counteract potential disturbances, or even manage reactive power for grid stabilisation. Of course, this comes back to the current the power semiconductor devices can provide, making the thermal management the bottle-neck. So, even when we look from the system level, the efficiency of the devices, is central, and the use of a digital twin can help ensure the best possible operation.
Of course, the increased complexity of a grid that is not just in following mode presents challenges for distribution system operators. But there is also an opportunity, as the power electronics converters provide an incredible source of data for system level optimization.
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