Rotating electric machine and compressor

A compressor, comprising:

• a compression mechanism for compressing a refrigerant;
• and
• a rotating electric machine for driving said compression mechanism, said rotating electric machine including
• a plurality of teeth circumferentially arranged around a predetermined axis forming a center of said teeth, each tooth having a first end disposed radially at an opposite side thereof from said predetermined axis,
• a back yoke having
• a circular outer periphery, and
• a cylindrical inner periphery connecting said first ends of said teeth,
• the outer periphery having a plurality of concave parts and a plurality of convex parts, the concave parts opening radially inwardly toward said teeth at positions overlapping with said teeth as viewed radially, at least one of the concave parts having two of the convex parts extending from respective circumferential ends of the at least one concave part, the two convex parts being symmetrical to each other with respect to a radial center line of a tooth of the plurality of teeth that is circumferentially aligned with the at least one concave part,
• an inflection point between a first of the two convex parts and the circular outer periphery of the back yoke being circumferentially spaced from an inflection point between the concave part and the first of the two convex parts with respect to a single circumferential side of the radial center line of the tooth circumferentially aligned with the at least one concave part, and
• a minimum distance measured from an exposure surface of each tooth to said concave part overlapping therewith being smaller than a radial width of said back yoke at a portion where said concave parts are not provided, said exposure surfaces extending radially inwardly of said inner periphery,
• a plurality of coils wound around said teeth with concentrated-winding,
• a plurality of insulating films with each insulating film interposed among said teeth, said back yoke, and said coils, and
• a case fixed to said back yoke by welding between an adjacent pair of said concave parts in said outer periphery,
• said refrigerant flowing through said concave part to said compression mechanism.