Medium-speed PMG + FPC – why not?

After the magnet price crises in 2011, interest in permanent magnet generators (PMG) was temporarily shaken. Luckily, the price crisis was short and even non-Chinese parties have now started to bring rare earth materials to the market. So, interest in permanent magnets (PM) is rising again.
Looking at the top players in the wind business, most of them are either carefully considering or already in process of applying PM technology, especially in the high-power class, thanks to the unquestionable benefits compared with other available technologies. There are only still a few major players who use other technology like EESG or DFIG. Now that Mitsubishi is starting cooperation with Vestas, it will be interesting to see their choice of technology – V164 (PM) or SeaAngel (hydraulic)?

What are the benefits of PM generators?

As PM technology can be applied to all wind turbine drive train topologies, you can choose the one that is best for your own purpose. Especially in the high-power range above 5 MW that is applicable to offshore the size of the direct-drive generator tends to be too large and the three-stage gearbox increases the risk of faults. Therefore, the medium-speed PMG with its two-stage gearbox seems to be the most attractive choice.

Medium-speed combines the best of both high-speed and direct-drive designs
– No 3rd stage in the gearbox
– Reduced weight and size
– Easy to transport

FusionDrive™, developed in cooperation between The Switch and gear manufacturer Moventas, is a good example of implementing the medium-speed advantages. FusionDrive™ is a fully integrated PMG with a two-stage gearbox. It offers high efficiency over the entire power range, has a reduced number of bearings and saves on space and weight. Its scalability and serviceability make it just right for nearly any application.

Making PMG a success

The Switch has been advancing PM technology with full-power converters since the start. We’ve pioneered its success and helped it move mainstream. That’s why we are one of the main players in the field today with the widest range of PMGs for wind power.
Although the future will show how the markets will develop, we are sure we made the right choice from the beginning…

Panu Kurronen
Product Manager