Variable speed generator optimizes turbine design

Variable speed generator optimizes turbine design

Synchrotek, Inc. offers a line of standard and custom electric generators that feature variable speed input, which permits the power source to rotate at its optimal speed. This arrangement is ideal for alternate energy systems, like wind turbines, where the power source is not constant. The wind turbine or other source can be tuned for maximum energy capture and is not limited by a narrow generator speed range.

In a typical wind turbine application, the wind speed can vary over a considerable range. In non-optimal areas, much of the time wind speed is between 5 and 10 mph, while it goes into the more ideal 15 to 25 mph range only a few days of the year. When the turbine has to accommodate the narrow speed range of an induction generator or the fixed speed of a wound-rotor generator, it cannot be optimized to capture all available wind power. The broad speed range of a Synchrotek, Inc. generator permits the wind turbine designer to optimize blade profile and blade pitch control for maximum energy capture, independent of rotational speed. In other variable speed applications, like hydro and waste process energy recovery, this input speed flexibility makes the variable speed input system attractive.

These generator systems include a permanent magnet generator combined with an electronic inverter, making them more compact and efficient than wound-rotor or induction generators. There is no exciter, which saves space and power. The high frequency design permits short end windings on the stator for reduced winding losses and space, and also reduces requirements for output power filters. Because of the modest losses, cooling requirements can be reduced for even greater power and packaging savings.

Generators can produce significant usable power between 20 and 125 percent of rated speed. The four-quadrant inverter efficiently converts the electricity from the generator voltage and frequency ranges to standard voltage and frequency, typically 480 volt, 60 Hz, 3 phase. The system can also include a battery in the DC inverter buss for energy storage in a hybrid system. The latest design is rated at 100 kW. The systems are suitable for stand-alone applications or for feeding power into the grid. Custom sizes and features can be designed upon customer request.

For additional information, contact Jeff Taylor at [email protected], 920-712-0025. Synchrotek, 610 Baeten Road, Green Bay, WI 54324.

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