Investigation On Electromagnetic And Temperature Rise Characteristics Of Variable Tooth Electromagnetic Actuator

Vibration of power machinery can interfere with other equipment in ships,vehicles,spaceflights and the means of other delivery,affect their work performance and life-span,and damage physical and mental health of occupants.And vibration isolation technology is one of the most important technological means for vibration control.Semi-active isolation system has the advantages of adapting to outside disturbance frequency change and abating the low frequency vibration effectively compared with passive isolation system,and requiring less additional energy,low prices and high reliability compared with active isolation system.As the implementation of the component,electromagnetic actuator is a critical component in the semi-active vibration isolation.Variable tooth electromagnetic actuator studied in this paper belongs to a special kind of electromagnetic actuator,which has good linearity,and further researches on its electromagnetic characteristic and temperature rise characteristic has great significance to optimize the system performance and improve the vibration control effect.In this paper,the electromagnetism model of variable tooth electromagnetic actuator was worked out with the software ANSYS and a test bench for the electromagnetic force measurement was built.The electromagnetic force of a prototype under different coil current was measured by experiment,and the precision of the simulation model was verified by comparing the experiment and simulation results,and the maximum deviation of electromagnetic force was 11.6%.Then,according to the simulation model,the influence rules of several parameters to electromagnetic force were deeply analyzed,including tooth height,coil turns,tooth number,air gap,armature thickness and yoke thickness,and the influence mechanisms were disclosed.The analytical model of variable tooth electromagnetic actuator was worked out by analyzing magnetic circuit in condition of no magnet saturation.Influence rules of several parameters,such as air gap,the difference between tooth width of stator and active cell,coil turns and the radius of the active cell,on actuator performance were analyzed based on the analytical model.And the necessity of applying variable tooth to gain good linearity was revealed theoretically and the realization of good linearity needed to be at the expense of decreasing electromagnetic force.To improve the linearity of variable tooth electromagnetic actuator as much as possible and minimize the decrease of electromagnetic force at the same time,genetic algorithm was applied to the optimal design.The results showed that variable tooth electromagnetic actuator can improve linearity by 93.08% under the condition of electromagnetic force was only dropped by 8.22%.The effectiveness of the analytical model and optimize results were proved by the calculation results carried out with the finite model which was verified by the experimental results.The lumped parameter thermal model was established according to the geometric structure and heat transfer characteristic of variable tooth electromagnetic actuator.The temperature test bench of processed prototype was set up to validate the accuracy of the developed lumped parameter thermal model.The experimental measured coil temperature and surface temperature of shell were compared with the calculation values of the lumped parameter thermal model at different coil voltages and the maximum deviation of coil temperature is 8.40%,surface temperature of shell is 9.22%.Then the sensitivity of temperature rise to thermal resistances were studied by the lumped parameter thermal,and the results showed that the temperature rise of variable tooth electromagnetic actuator is most sensitive to the thermal resistance between shell and environment.The coil and surface temperature would rise 6.10% and 8.40% respectively when the thermal resistance was increased 20%,and the other thermal resistances have little impact on the temperature rise of the actuator.Finally,the cooling methods of variable tooth electromagnetic actuator were studied and adding fins to the surface of the actuator shell under the condition of high current density is a practical method to improve the cooling effect.