The utility model relates to a permanent-magnet high-efficiency DC brushless motor used for an electric automobile, particularly an AC generator. When the AC generator drives other machines to do work, a part of alternating current is generated under the condition of no consumed electrical energy or no addition of any device. The utility model an air space regulating sleeve is added at the outer side of a permanent-magnet rotor; an excitation winding of a stator is designed as a six-phase winding; a coil does not crosses a groove. By the winding method of the AC generator, A is connected with A'in parallel, B is connected with B'in parallel, and C is connected with C'in parallel; the central position of each phase winding is tapped; afterwards, central taps of three-phase windings are connected in parallel. Because the rotor is made of permanent-magnet materials of rare-earth neodymium iron boron, no current passes through; besides, the excitation electrical energy is saved; when the motor does work, the motor can generate a part of alternating current; the alternating current can be changed into direct current by rectification to be fed back to an input power supply; a part of energy sources are automatically replenished. Thus, a motor which inputs the same electrical energy does work by one time. The utility model has the advantages of high efficiency, energy saving, favorable hard mechanical performance, simple structure and low cost.