Optimal Design Of Thrust Of Permanent Magnet DC Linear Motor

Permanent magnet DC linear motor (PMDCLM) is the characteristics of simple structure,large thrust, small electromagnetic pollution, high efficiency, etc. So the PMDCLM has cleartechnological advantage and promotional value in a variety of the occasion of reciprocatinglinear motion, such as national defense, automation, and machine. However，the significantdrawback of the PMDCLM is thrust ripple. The thrust ripple is the main cause of motor vibrationand noise. Especially at low speed, it may also cause resonance. It seriously affects theperformance of the motor running, and limits the performance improvement and the expansionof application fields of the PMDCLM. Therefore, from the view of the motor body design, thethrust ripple was analyzed and researched. The method to reduce the thrust ripple was proposed.On that basis, the structure of the motor was optimized to get the larger electromagnetic thrust.In the first place, this paper introduces the basic structure and the working principle of thePMDCLM. The advantages and disadvantages of the PMDCLM were analyzed. Secondly, themechanism of the PMDCLM cogging force was analyzed. According to the principle of virtualdisplacement, the mathematical expression of the cogging force has been got. The influencingfactors of the PMDCLM cogging force have been researched. And they were simulated byAnsoft. Some methods that minimize the cogging force were proposed. Then, the mathematicalexpression of the PMDCLM end force was obtained, using the Maxwell tensor method. Theeffect of the mover length, the mover shape and pole-arc coefficient on the end force wassimulated. And some methods that minimize the end force were proposed. Finally, according to amathematical model of the PMDCLM thrust, combined with optimization methods of the thrustripple, the structure of the motor was optimized. And it was verified by simulation experiments.Study results of this paper provide the systematic theories and methods to solve theproblems of the thrust fluctuation. The structural optimization methods of the PMDCLM thrustwere proposed. It creates the conditions for the expansion of application fields of the PMDCLM.