Classified by overall structure: ① Conventional alternator. This type of alternator has neither special devices nor special functional features and requires a voltage regulator for use. ② Integrated alternator. The alternator and regulator are made into a single integrated alternator. ③ Alternator with pump. The alternator and the vacuum booster pump for the car braking system are installed together. ④ Brushless alternator. An alternator that does not require brushes. ⑤ Permanent magnet alternator. The rotor poles are made of permanent magnets. (2) Classified by rectifier structure: ① 6-tube alternator. ② 8-tube alternator. ③ 9-tube alternator. ④ 11-tube alternator. (3) Classified by excitation winding grounding form: ① Internal grounding type alternator. ② External grounding type alternator.