The output of wind turbines has grown steadily over recent decades. This trend is set to continue in the future. In order to minimize cable cross-sections and cable losses within the tower, the transformer in modern wind turbines is housed in the nacelle. This also means that the power converter must be housed in the nacelle. This places high demands on the power converter's compactness, particularly as its power output triples when transitioning from double-fed asynchronous generators with partial converters to synchronous generators with full converters.

This is where the VollWind project comes in. The core idea is to significantly increase the power density of the power converter by eliminating the filter chokes. This disruptive approach places high demands not only on the power converter itself, but also on the generator and the transformer. At the same time, the power density of the power converter core itself must also be significantly increased, which requires novel power semiconductor modules.

The VollWind partners cover the entire chain, from power semiconductors and their drive systems, through power converter topologies and their control and regulation, right through to the development of complete power converters and their testing with upgraded generators and innovative transformers in the target application. In the sub-project led by the University of Rostock, research is being conducted into power converters that enable filterless operation. In this context, different topologies that enable a high resulting pulse frequency are being compared in terms of the required power-semiconductor configuration, and suitable control methods are being investigated. For the novel power semiconductor modules, control methods and driver circuits are being researched that enable filterless operation by avoiding steep voltage slopes.