Brushless DC (Direct Current) motor with brushless AC (Alternating Current) composite excitation

The invention discloses a brushless DC (Direct Current) motor with brushless AC (Alternating Current) composite excitation. When a stator excitation winding end adopts an AC variable frequency excitation winding, high excitation efficiency and wide excitation range at a low rotating speed are achieved; a rotor power excitation unit performs composite power excitation by using a DC winding and a permanent magnet; a stator power winding can perform excitation square wave electricity generation by adopting a three-phase or multi-phase winding; the motor running power density is great, and the running range is wide, so that brushless DC motor with the brushless AC composite excitation can be used for power generation running and electric running. The brushless DC motor with the brushless AC composite excitation comprises a stator excitation winding, a motor rotor and a stator power winding; the motor rotor comprises a rotor excitation winding, a rotary rectifier and the rotor power excitation unit; the rotor power excitation unit comprises the DC winding and the permanent magnet; the DC winding is wound on the permanent magnet, and the DC winding and the permanent magnet perform composite excitation.