Self cooler: A crafty draft

In the Saarland, wind-power stations are being developed and built that are reliable and set new standards with self-cooling forces — using EC technology.

Alone on the hill, the rotor of a wind-power station is rotating at a height of 69 metres. There’s quite a breeze blowing over Sitzerath in the north of Saarland. The screen of the installation control system indicates a wind speed of between 5 and 15 metres per second. Inside the steel tubes, that sounds like the groaning of a heavy worker. However, the humming is the satisfied sound of one of the lean giants rotating almost at its rated speed, known by the name of VENSYS 62 — the prototype from VENSYS Energy AG set up in 2003.

Our landscape is no longer conceivable without wind-power stations. However, they are not uncontroversial: too loud, too much shadow, too ugly is the criticism of many action groups and local communities. Yet beside these objections, wind-power stations provide great advantages: safe, almost environmentally neutral — and easy to maintain, being designed for longevity. “We simply left out much that could break”, explains Tanja Maringer succinctly. The stations, which are being developed in the Saarland, are simple, durable and reliable and will soon also be produced at the new location in Neunkirchen.

Maximum efficiency

The core of the gearbox-free wind turbine, of which the prototype was tested in Sitzerath, created a new state of the art, innovative generator technology. The generator is based on permanent magnet technology, which already existed for electric drives, but was now put into use for wind-power stations as well. With this external rotor motor generator, a charged field is created by permanent magnets made of neodymium-iron-boron. The main feature of this technology is that wear parts and susceptible additional components, such as collector rings to transfer the generated power, have been eliminated. The generator is perfectly protected against environmental influences. In addition, the power for the generator itself is saved, making it fully available as energy output — the electrical efficiency is outstanding.

With conventional technology, using a gearbox between rotor and generator, the power train is subject to extreme stress. In the worst case, the gearbox needs to be replaced after five to ten years — an expensive measure. The new gearless robust technology makes the VENSYS system, which is designed for a service life of twenty years, a low-maintenance and reliable alternative. The technology shows some amazing parallels with the EC motor developed by ebm-papst. Here too, a brushless, external rotor motor actuated by permanent magnets foregoes the need for components that wear and at the same time offers decisive advantages: simple controllability, durability, compactness — and up to 90 percent efficiency.

The gearbox-free technology in the wind-power station challenged the creativity elsewhere on the part of the developers, too: “We needed a suitable frequency inverter to transfer the electricity generated to a constant voltage and frequency”, explains Maringer, adding that the VENSYS frequency inverter is made by a subsidiary in Diepholz. A large number of semiconductors work in this frequency inverter — and they get hot, just like the transformer, which is also accommodated in the base of the tower.

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