© Photo | ebm-papst, Ralf Kreuels

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.

„Tanja Maringer knows
for sure: “To think green means to think econom­i­cally.”

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.

Self-cooling power

At this point, VENSYS and ebm-papst came together: “VENSYS approached us about the devel­op­ment of compo­nent cooling in the tower base”, recalls Winfried Schäfer, Regional Sales Manager at ebm-papst. About five years ago, the then Manager of the Elec­trical Depart­ment, Dr. Stephan Jöckel, had a ground­breaking idea: vensys_td Why not use the clean, cool air avail­able at the top of the tower to cool the frequency inverter and trans­former in the tower base, and the gener­ator? However, a stim­ulus was required. This was now provided by an EC axial fan in the tower door. The EC fan in the tower base gener­ates a slight under­pres­sure, which is suffi­cient to draw the air flow down through the entire tower to the base — a kind of reversed chimney effect. The air mass flow is directed via a distrib­utor on the inverter cabinet to the air-condi­tioning compo­nents of the PCBs inside — which also accom­mo­date further ebm-papst EC fans. Behind and below the inverter cabinet, the air is drawn further to the trans­former and finally blows warmth out of the tower base, making this an extremely econom­ical system of self-cooling forces. In addi­tion, in the forth coming WPS gener­a­tion, the EC axial fans will be equipped with HyBlade® blades. They combine the stability of a high-strength aluminium alloy with the light weight and unlim­ited mould­ability of fibre­glass-rein­forced plastic.

He who thinks green thinks econom­i­cally

Yet one might think that who ever is at the source need not neces­sarily save energy. However, Tanja Maringer disagrees: “He who thinks green thinks econom­i­cally.” For the Renew­able Ener­gies Law (EEG) guar­an­tees the oper­a­tors a fixed supply payment of currently 9.2 cents per kilo­watt hour. With an invest­ment sum of approx­i­mately 2 million Euro per instal­la­tion, the use of energy-effi­cient compo­nents is absolutely worth­while. “We are there­fore concerned that our instal­la­tions them­selves use as little power as possible”, concludes Maringer. Previ­ously, we did not directly approach poten­tial oper­a­tors with these compet­i­tive advan­tages, as the company acted primarily as a licenser. In the past five years we have gained licensees in the Czech Republic, Spain, India, Brazil and above all in China. Mean­while, 270 instal­la­tions are oper­a­tional world­wide, but the Chinese partner alone is plan­ning a further 1,000 instal­la­tions this year. Since the start of this year, VENSYS has been producing at the new company head­quar­ters in Neunkirchen itself. First of all, the 20 instal­la­tions planned for 2009 will be produced by order for the German and Euro­pean markets.

At the new site in Neunkirchen the future shines bright: in the new work­shop produc­tion is starting off — viewed by engi­neer Mike Becker, Winfried Schaefer of ebm-papst and Tanja Maringer (left to right)


  • 1990 Forschungs­gruppe Winden­ergie
  • 2000 VENSYS Energiesys­teme GmbH & Co. KG in Saar­brücken
  • 2007 VENSYS Energy AG
  • 2008 Moving to Neunkirchen

When the wind energy research group was founded at the Saar­brücken College of Tech­nology and Busi­ness in 1990, nobody realised that just ten years later there would be a successful spin-off. For after the group had success­fully devel­oped a gearbox-free wind turbine with an output of 600 kilo­watts for the company GenesYs, five members decided that they could them­selves develop and construct instal­la­tions. In the year 2000, there­fore, the company VENSYS Energiesys­teme GmbH & Co. KG was founded in Saar­brücken, with the proto­type VENSYS 62 which has an output of 1.2 megawatts. The young company won its first licensee: the firm Gold­wind in China, which today with 70 percent is the largest share­holder. Over the following three years, a further instal­la­tion type with an output of 1.5 megawatts and four more licensees were added. In 2007 the company changed its name to VENSYS Energy AG. In 2008 the subsidiary VENSYS Elek­trotechnik GmbH in Diepholz started with produc­tion of the self-devel­oped frequency inverter. In August 2008, the 40 employees moved from Saar­brücken to Neunkirchen and started their own produc­tion with ten new employees. By the end of 2009 it is intended to double this number and to have built 20 instal­la­tions.


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