Wind Technologies

Innovative drivetrain Demonstration projects

Economical benefits of the medium-speed Brushless DFIG drivetrain

Our new drivetrain technology comprises a medium-speed Brushless Doubly-Fed Induction Generator (Brushless DFIG) coupled to a simplified one or two stage gearbox. The Brushless DFIG retains the low-cost benefit of the conventional doubly-fed slip-ring induction generator (DFIG) solution, but also achieves the following unique advantages:

1- Low capital costs due to:

- elimination of slip-rings, brush-gear and carbon extraction system in the generator;

- utilization of a simplified 1 or 2-stage gearbox;

- utilization of a fractional-size converter;

- elimination/simplification of the complex hardware and software design (e.g crowbar) used for LVRT protection;

- lower drivetrain weight, hence lower structural costs;

2- High reliability and hence availability due to:

- elimination of slip-rings and brush-gear in the generator which are known as the highest failure rate components in the generator;

- elimination of high-speed stages of the gearbox which is known as the highest failure rate part in the gearbox;

3- Low operations & maintenance costs due to:

- eliminating the need for regular maintenance and replacement of slip-ring and brush-gear in the generator;

- higher reliability of drivetrain components, reducing the unplanned repair costs;

4- Improved grid compatibility due to:

- an intrinsically improved LVRT performance of the Brushless DFIG because it has higher rotor inductance by design;

- enhanced reactive current injection capability of the Brushless DFIG during grid faults;

5- Higher efficiency and hence gross energy production due to:

- reduced overall losses in the drivetrain comprising losses in the generator, converter and gearbox.