Abstract: The rotor of Nd-Fe-B permanent-magnet generating set is made up of a rotor core and much of the permanent-magnet material and pole shoes fixed on the core with non-magnetic screw. When the rotor rotates, N poles and S poles alternately pass the stator coils, and it generates electricity. With the developed three-phase half-controlled regulator, the generator will output rectified direct current from the regulator when the rotate speed is low and the output voltage is too low to achieve the target value. With the rise of the rotate speed, the output voltage is higher than the target value. And the comparator's voltage of the regulator is high enough to make the trigger turn off the three-phase half-controlled rectifier. The generator's voltage drops down quickly after the rectifier shuts off until there is no current through it. Then the output voltage is lower than the target value again, and the rectifier restores to work. Circularly, the generator will output stable direct current and solves the vehicle's problem of generating in low speed and the requirement of direct current.