Braking Circuit of Small Wind Turbine Using NTC Thermistor under Natural Wind Condition

An electric brake by a three-phase short-circuit system used as the brake equipment of a small wind turbine damages the rotor blades by a rapid revolution stopping of the generator. Moreover, the generators windings may also be damaged by a large short-circuit current. In this paper, the electric braking circuit using the NTC thermistors (negative temperature coefficient resistors) is proposed as a braking system for a cheaper and safe stop of the small wind turbine. The effect under the natural wind condition is examined by the field test using a 500W small wind turbine. AS a result, it is clarified that the generator can decelerates gradually and reduce the burst current by using the braking circuit that composed of the NTC thermisitors.