A tooth of a stator has a tapered shape in which a tooth width decreases toward a distal end portion thereof. A winding is formed of an edgewise winding wound around the tooth in a row. The winding is supplied with power so that a terminal on a base portion side of the tooth may have a higher voltage than that of a terminal on the distal end portion side thereof. A tooth width Th of the base portion is set within the range of Tmin