Niall McMahon

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On Electrodynamic Braking for Small Wind Turbines

N.M. McMahon*, Peter R. Burton1, David M. Sharman1

Wind Engineering 39(5), pp. 549556 . Preprint.

Straightforward analysis can show that it is difficult to implement a successful electrodynamic braking system for a small wind turbine system, i.e. of swept area less than 200 m2 and power rating of 50 kW. Two principal difficulties are: (i) the peak short-circuit torque of the electrical generator can be far too low to overcome the torques associated with the wind turbine rotor, even at wind speeds close to rated; (ii) the energy dumped into the generator during braking is significant and can cause swift heating to high temperatures. Transient electrical effects can also lead to electrical and electronic component failures. Documented failures in machines of up to 10 kW indicate that it is the case that electrodynamic braking is not well understood throughout the industry. Additionally, the academic literature on the topic is sparse. In this paper, we show how very straightforward analysis can shed light on the edge cases for electrodynamic brake systems and help to avoid expensive errors.

* Corresponding author.

1. Formerly of Ampair Energy.