An Electric Generator Driven by a Roof Ventilator

This paper develops the roof ventilator by adding three phase synchronous generator for voltage generating. The construction contains low flux density permanent magnet in rotational part and the three phase winding stator install at the ventilator base. When the ventilator rotate, the flux of the permanent magnet rotor part is moving across the air gap and induced the ac. voltage in the three phase stator winding. After that, the a.c. voltage is rectified to d.c. voltage and finally charged to the 12 V 5A lead-acid battery. The results of the generator performance are at the no-load speed 100 rpm, the generator voltage could be induced 52.3 V. At on-load, the generator could be supplied the load with the real power 1.15W. For the results after install the generator in the ventilator on the roof of a building to charge the 12 V battery, and the minimum wind speed for enough charging to battery is at 20 rpm. Additional to the efficiency of hot air ventilation after install the ac synchronous generator, the ventilation is just only reduced 0.13 m3/min or about 5.78% from the normally ventilation before installation generator 2.25 m3/min.