Study on Design and Application of BLDCM for Air-condition Compressor

　　Study on Design and Application of BLDCM for Air-condition Compressor
　　Permanent magnet brushless direct current motor(PMBLDCM) has good characteristic such as small inertia,easily controlled ,dynamic function well , therefore it has got extensive use in many field ,such as aerospace, robot, air-condition compressor control machine tool. The subject aimed at the air-condition compressor, has designed the BLDCM and corresponding control system.First, minimizing cogging torque is one of the main concerns of permanent magnet motor. In order to reducing the cogging torque of PMBLDCM , an analytical method, which was based on rubber magnetic sheet energy method and Fourier expansion, was proposed, which can express how to match slot and pole to reduce cogging torque. The research indicated that if the least common multiple between the slot and pole is 2pz, and the greatest common divisor is 1, the cogging torque can be greatly reduced. Being based on the expression,
　　PMBLDCM with similar pole and slot is selected . Further, the effect of pole-arc length on cogging torque is studied and the most suitable pole-arc length can be determined. The validity of the proposed method was verified by finite element analysis.Then, through BLDCM used in the air-conditioning compressor, as well as considering reduce motor’s vibration and the noise, two PMBLDCM were designed, including the 6 pole 36 slot and the multipolar few slot ,such as 8 pole 9 slot motor. With the aid of the Ansoft software ,design indicates that choosing multipolar few slot motor belonging to the approximate pole and slot, further choosing the suitable pole-arc coefficient, can reduce the cogging torque greatly and can reduce motor’s vibration and the noise. Above all, the multipolar few slot motor can be adopted in the air-conditioning compressor.At last,sensorless control technology has been a hot research in BLDCM control domain. This paper introduces the control system design for brushless DC motor based on PIC18F4580, discusses in detail the current http://www.chinamagnets.biz/rubber/rubber-magnetic-sheet.php commutation and motor speed computation, and designs the corresponding software circuit. In order to improve speed control performance of motor, this paper adopts the double-closed-loop control strategy and gives the corresponding implement methods.Designing BLDCM initial data scheme, Ansoft carrying out verification on electromagnetism design , designing PIC monolithic machine controls system are the main parts. Above this three parts, this paper have accomplished BLDCM design and application for air-conditioning compressor.