Abstract: A brushless dc motor applied to ac power in accordance with the present invention includes a conversion circuit. The conversion circuit includes a metallized film capacitor, a rectifier and a filter. The metallized film capacitor is serially connected to an ac power source, and adapted to supply with a rated ac voltage for the brushless de motor. The metallized film capacitor is further serially connected to the rectifier and the filter. The rectifier is converted an alternating current supplied from the metallized film capacitor into a direct current. The filter is filtered the direct current supplied from the rectifier and then sent to a motor drive circuit.