The D3.0 generator, with a diameter of 3 meters and custom pole and coil segment lengths for different performance classes, previously served all variants of LEITWIND platforms LTW77, LTW80 and LTW86.
It has now been replaced by a larger model for all performance classes over 1.5 MW. The design of the new D4.1 generator, with a diameter of 4.1 m, is based on the LTW101 generator. To achieve a torque of 2230 kNm for generating 3.0 MW with the LTW101, a generator with a larger diameter was required. This development provided the foundations for the D4.1, which now brings all of the advantages of the larger diameter to the smaller platforms, as well as the new LTW90 platform.
Compared with the D3.0 generator, the larger diameter of the new generator reduces manufacturing costs, as it allows the length and thus the mass of the active parts to be reduced without decreasing the torque. One advantage of the shorter structure of the D4.1 is the increased stiffness and stability of the generator, which reduce the internal forces in the generator significantly, resulting in particularly smooth and reliable operation.
As the D4.1 generator is designed for performance classes up to 2.0 MW, it has a highly efficient cooling system with a water-cooled stator and an air-cooled rotor, which also increases the efficiency of the entire power train. The D4.1’s electrical system is highly modular: It has separate electrical systems organized in 250 kW clusters, which are each regulated independently by a LEITDrive converter. If one system or converter fails, all other systems can continue to generate electricity, and the turbine remains on the grid.
The generator was developed in two stages: First, a prototype was produced, installed and tested on a wind turbine. It was then optimized for function and costs, and industrialized. This was especially challenging for the development team of specialist engineers with experience in wind power. The main focus was on the development of the structural components to realize the large diameter. Also the development of the electrical and electromagnetic/thermal systems required high in-depth expertise in these fields.
The development of the prototype began in 2014 followed by its installation in Tadipatri, India just one year later. Currently the components of the industrialized version are in production. After the successful validation of the generator on a wind turbine it is supposed to be used in all LEITWIND wind turbine types with nominal outputs of 1.5 MW or higher.