Brushless dc motor with large air gap

✍ Scribed by Yoshinobu Nakamura; Motoyasu Mochizuki; Fuminori Ishibashi

• Book ID: 101292808
• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 150 KB
• Volume: 125
• Category: Article
• ISSN: 0424-7760
• DOI: 10.1002/(sici)1520-6416(19981130)125:3<67::aid-eej8>3.0.co;2-#

✦ Synopsis

The authors propose a new brushless dc motor for pumps, with a large air gap of 8 mm, compared with the conventional gap of 1 mm. The conventional pump system is composed of an induction motor, a magnetic coupling, and a magnetic rotor with vane. This rotor receives power from the magnetic coupling. In the new motor, the rotor has a vane without magnetic coupling. The air gap is very large in order to provide a seal between the stator and rotor. The seal protects the stator coil against liquids such as water and chemicals. The performance of the motor was analyzed by FEM and compared with experimental results. The analytical results agreed with experimental results with good accuracy. In the experiments using a four-pole 0.75-kW test motor and high-efficiency drive inverter with power factor control, the motor efficiency was about 88%, and the motor power factor was about 98%.