Research On Physical Field Of Permanent Magnet Brushless DC Torque Motor In Low Ambient Pressure Conditions

As a newly developed torque motor, brushless DC torque motor is easy to controland has simple structure, which is the same as brushed DC torque motor. Meanwhile,brushless DC torque motor, which is excited by permanent magnets, as a result of highmagnetic energy density, small size, and high precision in control, plays an increasinglyimportant role in some high demanding applications such as aerospace field.Research of brushless DC torque motor related to physics field becomes more andmore significant, following the widespread use of BLDC torque motor. Generally,Brushless DC torque motor has high electromagnetic loads, resulting in great energyloss and severe motor heating problems. The speed is low, so the loss is determinedmainly copper loss. Small size and large output torque of the rotor determines thebearing of the mechanical strength requirements. Thus, this paper studies these issues inthe following parts:First, electromagnetic structure of brushless DC torque motor is designed, which isspecific to given design specification of voltage, loss, torque and so on. And in no-loadcondition, electromagnetic field is analyzed by means of the finite element method.Besides, in rated operating condition, the parameters of the motor are simulated in bothsquare and sine drive, and the feasibility of the design plan is discussed as well.Second, the motor is working off the ground, hence the weight problem is crucial.To address this problem, the motor rotor is designed as special mid-empty structure, soas to connect with other mechanical parts, which contributes to a considerable volumedecrease of the whole mechanical system. However, the mechanical strength that rotormay bear cannot be ignored in this case. Because the higher output torque the motor has,the greater force that rotor may bear, the stress field of the rotor needs to be calculatedand checked for strength. According to the result of stress calculations, the structure ofthe rotor is undertook relevant optimizations so that various parts of the rotor arereduced in weight and the design of rotor is optimized.Moreover, the steady temperature field of motor is calculated in the rated workingconditions on account of high electromagnetic load, including the temperature field inboth air and vacuum situation. The finite element simulation model in the air is set up,and so is in the vacuum environment. And the steady state of temperature rise of themotor is calculated on base of the result of loss. Whether the motor can operatenormally in the actual work environment could be discussed base on the obtained resultsand the material properties of various motor parts.Finally, after the manufacture of prototype, experiments of the electromagneticproperties and the temperature distribution of the motor are conducted to verify the results of the simulation. The obtained experimental data provides the basis for theactual operation of motor, which is beneficial for the next round of optimization, andprovides a reference for future motor design.