Abstract: A universal motor includes a wound rotor and a stator. The stator has stator windings and a stator code. The stator core has at least two poles with the stator windings wound thereon and a yoke connecting the poles. Each pole has a neck and a pole shoe forming a continuous pole arc facing the rotor. The ratio of the diameter of the motor to the width of the stator core measured across the poles is between 0.65˜0.95.

Abstract: An electric motor has a stator and a rotor magnetically coupled to the stator. The rotor has a shaft, a rotor core fixed to the shaft and having a plurality of teeth, a commutator fixed to the shaft adjacent the rotor core and having a plurality of segments, and rotor winding units wound about the teeth and connected to the segments. Brushes arranged in sliding electrical contact with the commutator transfer power to the rotor. Each of the rotor winding units has at least two subcoils directly connected in series to each other and separated from each other by at least one tooth. An initial subcoil and a final subcoil of each rotor winding unit are respectively directly connected to two adjacent segments.

Abstract: A universal motor includes a wound rotor and a stator. The stator has stator windings and a stator core. The stator core has at least two poles with the stator windings wound thereon and a yoke connecting the poles. Each pole has a neck and a pole shoe forming a continuous pole arc facing the rotor. The ratio of the diameter of the rotor to the width of the stator core measured across the poles is between 0.65˜0.95.

Abstract: An electric motor has a stator and a rotor magnetically coupled to the stator. The rotor has a shaft, a rotor core fixed to the shaft and having a plurality of teeth, a commutator fixed to the shaft adjacent the rotor core and having a plurality of segments, and rotor winding units wound about the teeth and connected to the segments. Brushes arranged in sliding electrical contact with the commutator transfer power to the rotor. Each of the rotor winding units has at least two subcoils directly connected in series to each other and separated from each other by at least one tooth. An initial subcoil and a final subcoil of each rotor winding unit are respectively directly connected to two adjacent segments.